阅读说明：本技术 部件的制造方法、汽车用部件的制造方法以及模具 (Method for manufacturing part, method for manufacturing automobile part, and mold ) 是由 佐藤雅彦 吉田亨 于 2020-03-27 设计创作，主要内容包括：本发明提供部件的制造方法、汽车用部件的制造方法以及模具。本发明的某个观点涉及的部件的制造方法制造具备特定三维筒状部的部件,其包括：U成型工序,使用包括U成型冲头的U成型模具对上述金属材料板进行U成型,由此制造截面观察凹形状的U成型品；以及O成型工序,通过O成型模具将上述U成型品的侧端部彼此抵接,由此形成抵接部,成型条件比a＝Du/Do被设定为0.85以上0.95以下。(The invention provides a method for manufacturing a part, a method for manufacturing an automobile part, and a mold. A method for manufacturing a member according to an aspect of the present invention is a method for manufacturing a member having a specific three-dimensional cylindrical portion, the method including: a U-forming step of forming a U-shaped product having a concave cross-section by U-forming the metal material plate using a U-forming die including a U-forming punch; and an O-molding step of forming an abutting portion by abutting the side end portions of the U-shaped molded product with an O-mold, wherein a molding condition ratio a is set to 0.85 to 0.95.)

1. A method for manufacturing a component, which is provided with a specific three-dimensional cylindrical portion including at least one of a cross-sectional shape changing portion in which a cross-sectional shape of the cylindrical portion changes along a shape center line, a circumference length change rate changing portion in which a circumference length of the cylindrical portion changes along the shape center line and a change rate of the circumference length changes, and a curved portion in which the shape center line of the cylindrical portion has a curvature, by processing a metal material plate, the method comprising:

a U-forming step of forming a U-shaped product having a concave shape in cross section by U-forming the metal material plate using a U-forming die including a U-forming punch; and

an O-molding step of forming an abutting portion by abutting the side end portions of the U-shaped molded product with an O-mold,

a molding condition ratio a, which is a ratio of a punch width Du of a portion of the U-shaped punch corresponding to the specific three-dimensional cylindrical portion to a recess width Do of a portion of the O-shaped die corresponding to the specific three-dimensional cylindrical portion, is set to be 0.85 to 0.95.

2. The method of manufacturing a component according to claim 1,

The U-shaped forming die includes a press-forming punch as the U-shaped forming punch and a press-forming die having a press-forming recess corresponding to the press-forming punch,

the U-forming process includes:

a press-forming step of relatively moving the press-forming punch in a direction approaching the press-forming die to form the metal material plate into a press-formed product having a concave portion as viewed in cross section and protruding portions protruding outward from both side end portions of the concave portion as viewed in cross section; and

and a flangeless step of removing the protruding portion from the press-formed article to produce the U-shaped article.

3. The method of manufacturing a component according to claim 1,

the U-shaped forming die has a bending punch as the U-shaped forming punch and a bending die having a bending recess formed therein corresponding to the bending punch,

the U-forming step is to relatively move the bending punch in a direction approaching the bending die, thereby producing the U-formed product.

4. The method of manufacturing a component according to any one of claims 1 to 3,

Further comprises a molding condition ratio setting step of performing 1 or more cycles before the U-molding step,

the molding condition ratio setting step is a step of,

estimating shape parameters by performing finite element analysis in consideration of conditions including the molding condition ratio a set in the molding condition ratio setting step or an initial value of the molding condition ratio a, the material characteristics of the member, the shape and the plate thickness of the metal material plate, the molding condition in the U molding step, and the molding condition in the O molding step, which have been circulated in the past, the shape parameters including the amount of strain in the specific three-dimensional cylindrical portion in the direction along the centroid line generated in the U molding step, the amount of strain in the specific three-dimensional cylindrical portion in the direction along the centroid line generated in the O molding step, and the relative positions of the side end portions,

the molding condition ratio setting step is repeated until the shape parameter satisfies a desired condition.

5. The method of manufacturing a component according to any one of claims 1 to 4,

the molding condition ratio a varies along the shape center line of the specific three-dimensional cylindrical portion.

6. A method for manufacturing a member for an automobile,

a method of manufacturing using a component as claimed in any one of claims 1 to 5.

7. A mold for use in a method of manufacturing a component according to any of claims 1 to 5,

comprises the U-shaped mold and the O-shaped mold,

the molding condition ratio a is set to 0.85 to 0.95.

8. The mold according to claim 7,

the U-shaped die includes a press-forming punch as the U-shaped punch, and a press-forming die in which a press-forming recess corresponding to the press-forming punch is formed.

9. The mold according to claim 7,

the U-forming die includes a bending punch serving as the U-forming punch and a bending die having a bending recess corresponding to the bending punch.

10. The mold according to any one of claims 7 to 9,

the molding condition ratio a is a value set by a molding condition ratio setting step performed in 1 or more cycles,

the molding condition ratio setting step is a step of,

estimating shape parameters by performing finite element analysis in consideration of conditions including the molding condition ratio a set in the molding condition ratio setting step or an initial value of the molding condition ratio a, the material characteristics of the member, the shape and the plate thickness of the metal material plate, the molding condition in the U molding step, and the molding condition in the O molding step, which have been circulated in the past, the shape parameters including the amount of strain in the specific three-dimensional cylindrical portion in the direction along the centroid line generated in the U molding step, the amount of strain in the specific three-dimensional cylindrical portion in the direction along the centroid line generated in the O molding step, and the relative positions of the side end portions,

The molding condition ratio setting step is repeated until the shape parameter satisfies a desired condition.

11. The mold according to any one of claims 7 to 10,

the molding condition ratio a varies along the shape center line of the specific three-dimensional cylindrical portion.

Technical Field

The present invention relates to a method for manufacturing a member having a cylindrical portion formed from a metal material plate, a method for manufacturing an automobile member, and a mold.

The present application claims priority based on Japanese patent application Nos. 2019-066238 and 2019-066239 filed on 29.3.2019, and the contents of which are incorporated herein by reference.

Background

As is well known, various vehicle suspensions have been put into practical use in the automobile industry depending on the application.

For example, the torsion beam type suspension device is configured to include: a torsion beam assembly capable of rotatably supporting left and right wheels by arms and having one end of a spring disposed near the left and right ends; a spring connecting the torsion beam with the vehicle body; and a damper.

The torsion beam assembly is connected to a pair of left and right trailing arms that rotatably support left and right wheels, for example, by a torsion beam, and a pair of spring receiving portions are formed near left and right ends of the torsion beam.

The torsion beam assembly is connected to the vehicle body via a pivot shaft extending from the left and right sides of the vehicle body toward the center, whereby the left and right wheels swing with respect to the vehicle body.

Further, the load received from the road surface is transmitted to the vehicle via the wheel, the trailing arm, and the spring on the side of the spring seat portion where the one end of the spring is disposed. Thus, for example, greater loads may be applied to the trailing arm, requiring greater strength.

As described above, automobile parts (for example, link parts and the like) represented by trailing arms are required to have high strength, and on the other hand, weight reduction is often required. For this reason, a cylindrical complicated shape is required. For example, the automobile component may have a specific three-dimensional cylindrical portion formed with at least one of a circumferential length change rate changing portion in which a circumferential length (a circumferential length of a cross section orthogonal to the shape axis) changes along a change rate of the shape axis, a cross-sectional shape changing portion in which a shape of a cross section orthogonal to the shape axis changes along the shape axis, and a curved portion in which the shape axis has a curvature. Conventionally, when manufacturing a tubular automobile component from a metal material plate, a joint portion is often welded after being formed by press working in a plurality of steps including intermediate trimming, and it is difficult to easily reduce the cost (for example, see patent documents 1 and 2).

On the other hand, in the production of thick straight round pipes represented by line pipes, the following UO molding method is used: a steel plate (metal material plate) is subjected to U-shaped forming (e.g., press forming or bending forming) in cross section, and then a circular tube (cylindrical body) having a circular cross section is subjected to O-forming (see, for example, patent document 3).

Further, the roundness after the abutment portion forming process for the straight round pipe and the adhesion of the joint portion are technically established by sufficiently examining the influence of the ratio a (Du/Do, hereinafter referred to as the molding condition ratio a.) of the width Du of the U-forming punch and the width Do of the recess portion of the O-forming die (abutment portion forming die) from both the analysis and the experiment (for example, refer to non-patent document 1.).

In recent years, however, in the UO molding method, a technique for efficiently manufacturing a part (automobile part) having the specific three-dimensional cylindrical portion is desired.

Documents of the prior art

Patent document

Patent document 1: japanese patent No. 3114918

Patent document 2: japanese patent laid-open No. 2012 and 115905

Patent document 3: japanese patent laid-open publication No. 2004-141936

Non-patent document

Non-patent document 1: "analysis concerning the shape of molded article (Chuansheng Hai, Huzekanshou)" (plasticity and processing, vol.21no.230(1980) P234 to P240

Disclosure of Invention

Problems to be solved by the invention

However, for example, patent document 3 discloses a technique of performing UO molding by setting a molding condition ratio a (Du/Do) of a width Du of a punch and a recess width Do of an O-mold to 0.7 or less (preferably 0.65 or less) for improving circularity, for a thick straight circular tube (API X60 or more, a wall thickness/outer shape ratio of 4% or more), but the technique is not suitable for accurately abutting the portion to be abutted of the specific three-dimensional cylindrical portion.

Further, it can be said that, for example, parts including three-dimensional shapes, such as automobile parts having the specific three-dimensional cylindrical portion, cannot be manufactured using ultra-high-strength steel.

Further, in a thin-walled cylindrical portion (having a wall thickness/outer diameter ratio of 10% or less) represented by an automobile component, when the molding condition ratio a (Du/Do) is too small, the closed cross section after the contact portion forming step becomes a vertically long oval shape and the roundness decreases, and therefore, there is a problem that it is difficult to apply the thin-walled portion to a thin-walled component.

Further, the research results described in non-patent document 1 also target straight circular tubes, and are difficult to apply to a cylindrical portion including a three-dimensional shape other than circular tubes whose circular closed cross sections are linearly continuous, for example, the above-described specific three-dimensional cylindrical portion.

Further, in the case of manufacturing a member having the above-described specific three-dimensional cylindrical portion by applying UO molding, a gap may be generated between the abutting portions (portions to be joined) due to springback. Therefore, when joining the abutting portions, it is necessary to join the abutting portions while restraining the abutting portions and minimizing the gap generated in the abutting portions. However, in this case, the abutting portion needs to be restrained at the time of joining, and there arises a problem that workability deteriorates and productivity decreases, such as a complicated jig for restraining the tube.

In particular, a high-strength and thin steel sheet to be applied to an automobile part is desired, and since a large spring back causes a large gap in a contact portion, it is very difficult to closely attach the three-dimensional shape of the cylindrical portion by a jig or the like. Therefore, the following techniques are desired: the cylindrical portion having a three-dimensional shape and a modified cross section, particularly the portion to be abutted by the specific three-dimensional cylindrical portion, can be brought into close contact with high accuracy, and the component can be efficiently manufactured.

The present invention has been made in view of such circumstances, and an object thereof is to provide a method for manufacturing a member, a method for manufacturing an automobile member, and a mold, which can efficiently form (manufacture) a member having the specific three-dimensional cylindrical portion by processing a metal material plate.

Means for solving the problems

In order to solve the above problems, the present invention proposes the following means.

According to an aspect of the present invention, there is provided a method of manufacturing a component including a specific three-dimensional cylindrical portion including at least one of a cross-sectional shape changing portion in which a cross-sectional shape of the cylindrical portion changes along a shape axis, a circumferential length change rate changing portion in which a circumferential length of the cylindrical portion changes along the shape axis and a change rate of the circumferential length changes, and a curved portion in which the shape axis of the cylindrical portion has a curvature, the method including: a U-forming step of forming a U-shaped product having a concave shape in cross section by U-forming the metal material plate using a U-forming die including a U-forming punch; and an O-molding step of forming an abutting portion by abutting the side end portions of the U-shaped product with an O-mold, wherein a molding condition ratio a, which is a ratio of a punch width Du of a portion of the U-shaped punch corresponding to the specific three-dimensional cylindrical portion to a recess width Do of the O-mold corresponding to the specific three-dimensional cylindrical portion, is set to 0.85 to 0.95.

According to another aspect of the present invention, there is provided a method for manufacturing an automobile part, wherein the method for manufacturing the automobile part is applied.

According to another aspect of the present invention, there is provided a mold used in the method for manufacturing the member, the mold including the U-mold and the O-mold, wherein the molding condition ratio a is set to be 0.85 to 0.95.

According to the method for manufacturing a component, the method for manufacturing a component for an automobile, and the die in the aspects of the present invention, since the molding condition ratio a, which is the ratio of the width Du of the press punch used when the U-shaped product is molded from the metal material plate in the U-molding step to the width Do of the recess of the O-molding die used in the O-molding step for bringing the side ends of the U-shaped product into contact with each other (the width of the recess formed by the contact portion), is set to 0.85 or more and 0.95 or less, the spring back can be appropriately suppressed, and the side ends of the specific three-dimensional cylindrical portion formed in the O-molding step can be brought into accurate and effective close contact with each other or brought close to the target position. Here, when the molding condition ratio a is less than 0.85, the springback of the specific three-dimensional cylindrical portion becomes excessively large, and the closed cross section (cross section orthogonal to the longitudinal direction) of the specific three-dimensional cylindrical portion greatly deviates from the target shape. For example, when the target shape is a perfect circle, the closed cross section is a vertically long ellipse, and the roundness is reduced. When the molding condition ratio a exceeds 0.95, the side end portions of the specific three-dimensional cylindrical portion formed in the O-molding step are not sufficiently adhered to each other.

Further, since the end portions of the portions to be abutted are disposed in close contact with each other or in a state close to the target after the O-molding step, the joining can be efficiently performed without complicating a jig or the like.

Further, since the molding condition ratio a is set to less than 1.0, the U-shaped article can be easily arranged in the O-mold.

As a result, the tubular portion formed of the specific three-dimensional tubular portion and the tubular portion at least partially formed as the specific three-dimensional tubular portion can be efficiently formed, and further, the parts and the automobile parts can be easily reduced in weight and the manufacturing cost can be reduced.

Here, the U-forming die may include a press-forming punch serving as the U-forming punch and a press-forming die in which a press-forming recess corresponding to the press-forming punch is formed, and the U-forming step may include: a press-forming step of relatively moving the press-forming punch in a direction approaching the press-forming die to form the metal material plate into a press-formed product having a concave portion as viewed in cross section and protruding portions protruding outward from both side end portions of the concave portion as viewed in cross section; and a flangeless step of removing the protruding portion from the press-molded article to produce the U-shaped article.

In the present specification, press forming means forming a press-formed product by a press-forming punch and a press-forming die having a press-forming concave portion formed therein. More specifically, the present invention is directed to a method of pressing a metal material plate outside (lateral portion) a press-forming concave portion with a metal material pressing tool (e.g., a blank holder), relatively moving (advancing) a press-forming punch in a direction approaching a press-forming die, and observing a concave portion in a forming cross section of the metal material plate while pressing a protruding portion protruding outward from an end portion of the press-forming concave portion.

The flangeless process is a process of forming a press-formed product (i.e., a flangeless press-formed product) without the above-described protruding portion, and includes, for example, a process of removing, by trimming or the like, the protruding portions in a flange shape protruding outward from both side end portions of the concave shape in cross section after press-forming, a process of forming a part of the concave shape in cross section by press-fitting the protruding portion temporarily formed at the time of press-forming into the press-formed concave portion, a process of bending the protruding portion temporarily formed to form a part of the concave shape in cross section, and the like. The flangeless press-formed article is a form of press-formed article, and may be simply referred to as a press-formed article.

In the present specification, the term "to-be-abutted" includes not only bringing the corresponding side end portions of the flangeless press-molded product into close contact with each other, but also, for example, forming a gap (target gap) to such an extent that the side end portions can be joined by welding or the like, forming a gap in a part of the side end portions after the close contact, and arranging the side end portions in proximity to each other with a predetermined gap over the entire length of the side end portions.

In the case where the gap is formed, the gap may be formed at a different interval from other intervals. That is, it need not be constant throughout the entire interval.

In addition, the U-forming die may include a bending punch serving as the U-forming punch and a bending die having a bending recess formed therein corresponding to the bending punch, and the U-forming step may be performed by relatively moving the bending punch in a direction approaching the bending die to manufacture the U-shaped product.

In the present specification, the bending means forming the U-shaped portion by a bending punch and a bending die, and more specifically, when the metal material plate is pressed by the bending punch, the metal material plate is formed without being pressed by a bead or the like. That is, the main point of the bending is to form no protruding portions (flange portions) protruding outward from both side end portions of the metal material plate having a concave shape in cross section, or no excess material generated by drawing.

In the present specification, the longitudinal direction refers to a direction in which an elongated member (e.g., a member having a specific three-dimensional cylindrical portion) extends. The centroid line is a line connecting centroids of minimum cross sections (i.e., cross sections orthogonal to the longitudinal direction) in which the cross sectional area becomes minimum at each portion of the cylindrical portion in the longitudinal direction.

It is needless to say that the advancing/retreating direction of the press-forming punch in the press-forming step and the relative movement direction of the 1 st die and the 2 nd die (the dies constituting the O-forming die) in the O-forming step do not need to be the direction perpendicular to the centroid line.

The cross-sectional shape of the cylindrical portion is a shape of a cross-section of the cylindrical portion orthogonal to the centroid line (longitudinal direction). The circumferential length changing portion is a portion where the circumferential length defined orthogonally to the shape axis (i.e., the length of the outer circumference circle of the cross section orthogonal to the shape axis (longitudinal direction)) in the cylindrical portion changes along the shape axis, and can be determined by the case where the circumferential length changes at two arbitrary points along the shape axis.

In the circumferential length change portion, a value (percentage) obtained by dividing the difference in circumferential length between two arbitrary points set along the centroid line by the length along the centroid line between the two points is referred to as a circumferential length change rate.

The circumferential length change rate changing portion is a portion where the circumferential length change rate changes along the shape line.

Here, after the concave portion in the cross-sectional view and the protruding portion are formed in the press-forming step, the press-forming punch may be further advanced to perform the flangeless step.

From this viewpoint, since the flangeless step is performed by further advancing the press punch after the concave portion and the protruding portion as viewed in cross section are formed in the press forming step, the protruding portion required for pressing the metal material plate can be formed into a flangeless press formed product without removing the press formed product from the U-shaped die.

As a result, the flangeless molded product can be efficiently formed without providing a step of trimming the protruding portion required for pressing the metal material plate, and productivity can be improved.

Further, the opposing punch of the press-forming die may be moved forward and backward relative to the press-forming recess in a forward and backward direction of the press-forming punch.

Here, the counter punch may be provided in the press-forming die.

From this viewpoint, the press-formed product can be sandwiched and pressed by the opposing punch and the press-forming punch of the press-forming die, and therefore the press-formed product can be efficiently manufactured.

In addition, the cross-sectional shape changing portion may change the length of the cross-sectional shape (the shape of the cross-section orthogonal to the shape axis of the cylindrical portion) in the direction including the shape axis and the abutting portion (that is, the length of a line segment that passes through the shape axis and the abutting portion of the cross-section and intersects the outer periphery of the cross-section) by 10% to 50% along the shape axis.

Here, the mold may be designed such that the cross-sectional shape changing portion has the above-described characteristics.

From this viewpoint, the cross-sectional shape changing portion is a cross-sectional shape changing portion in which the length of the cross-sectional shape in the direction including the shape axis and the abutting portion (i.e., the press forming direction) changes by 10% to 50% along the shape axis, and a member including a cross-sectional shape changing portion that is difficult to form can be efficiently manufactured.

Here, the cross-sectional shape changing portion is a portion where the cross-sectional shape orthogonal to the centroid line changes along the centroid line.

The change in the cross-sectional shape of the cross-sectional shape changing portion is represented by a value (percentage) obtained by dividing the difference between the lengths of the cross-sectional shapes at two arbitrary points along the centroid line in the direction including the centroid line and the abutting portion by the length along the centroid line between the two points.

Further, the change in the circumferential length change rate of the 1 st end and the 2 nd end of the circumferential length change rate changing portion may be 0.035mm^-1Above 0.35mm^-1The following.

Here, the mold may be designed such that the peripheral length change rate changing portion has the above-described characteristic.

From this viewpoint, the change in the circumferential length change rate of the 1 st end and the 2 nd end of the circumferential length change rate changing section was set to 0.035mm^-1Above 0.35mm^-1Hereinafter, a member difficult to mold can be efficiently produced.

Here, the circumferential length change rate changing portion is a portion where the circumferential length change rate of the tube portion changes along the shape axis, and mathematically means a portion where the circumferential length change rate obtained by differentiating the circumferential length change amount along the shape axis changes along the shape axis.

The change (value) of the circumferential length change rate between the 1 st end portion and the 2 nd end portion of the circumferential length change rate changing portion is defined by a value (absolute value) obtained by dividing the difference in the circumferential length change rate between the 1 st end portion (starting point) and the 2 nd end portion (ending point) of the circumferential length change rate changing portion by the interval (length, size) between the 1 st end portion and the 2 nd end portion along the centroid line.

The circumferential length change rate can be calculated based on, for example, a curved surface shape measured by a shape measuring device or data measured by another measuring method. Other parameters related to the shape of the present invention can be measured by the same method.

Further, the curvature of the centroid line at the curved portion may be 0.002mm^-1Above 0.02mm^-1The following ranges.

Here, the mold may be designed such that the bent portion has the above-described characteristics.

From this viewpoint, it is possible to efficiently manufacture a product having a shape line including the cylindrical portion and a curvature of 0.002mm^-1Above 0.02mm^-1And a part having a bent portion which is difficult to mold in the following range.

Further, the molding condition ratio a may be changed along the shape center line of the specific three-dimensional cylindrical portion.

Here, the mold may be designed such that the molding condition ratio a has the above-described characteristics.

From this viewpoint, since the molding condition ratio a varies along the centroid line of the specific three-dimensional cylindrical portion, the side end portion can be brought into close contact with or close to the target position accurately and effectively over the entire length of the contact portion of the specific three-dimensional cylindrical portion.

The method of manufacturing a component according to this aspect may further include a molding condition ratio setting step of performing 1 or more cycles before the U-molding step, the molding condition ratio setting step estimating a shape parameter by performing finite element analysis in consideration of conditions including the molding condition ratio a set in the molding condition ratio setting step of the previous cycle or an initial value of the molding condition ratio a, a material characteristic of the component, a shape and a plate thickness of the metal material plate, the molding condition in the U-molding step, and the molding condition in the O-molding step, the shape parameter including a strain amount in a direction along a centroid line of the specific three-dimensional cylindrical portion due to the U-molding step, a strain amount in a direction along the centroid line of the specific three-dimensional cylindrical portion due to the O-molding step, and a strain amount in a direction along the centroid line of the specific three-dimensional cylindrical portion due to the O-molding step, And the relative position of the side end portions, and repeating the molding condition ratio setting step until the shape parameter satisfies a desired condition.

Here, the mold may be designed based on the molding condition ratio a designed in the molding condition ratio setting step.

From this viewpoint, by performing finite element analysis in consideration of conditions including a molding condition ratio a, material characteristics of the member, a shape and a plate thickness of the metal material plate, a molding condition in the U molding step, and a molding condition in the O molding step, a shape parameter including a strain amount in the direction along the centroid line of the specific three-dimensional cylindrical portion generated in the U molding step, a strain amount in the direction along the centroid line of the specific three-dimensional cylindrical portion generated in the O molding step, and a relative position between the side end portions is estimated. Then, since the molding condition ratio a is set based on the shape parameter, the accuracy of the molding condition ratio a can be further improved, and the specific three-dimensional cylindrical portion can be formed more efficiently and stably.

In the present specification, the material properties of the member refer to the young's modulus, yield strength (proof stress), relationship between stress and strain in a tensile test (stress-strain curve, etc.), and the like of the material constituting the member.

The shape and the thickness of the metal plate are the shape and the thickness of the metal plate formed in accordance with the component and the specific three-dimensional cylindrical portion.

The forming conditions in the U forming step include, for example, the width Du of the U forming punch (e.g., press forming punch and bending punch), the shape of the forming die (e.g., press forming die and bending die), the forming load in the U forming step, and the displacement of the U forming punch with respect to the forming die (relative position between the forming die and the U forming punch) in the U forming step.

The molding conditions in the O-molding step are the shape of the concave portion formed by the contact portion of the O-mold (including the concave portion width Do), the molding load in the O-molding step, or the displacement of the 2 nd die with respect to the 1 st die in the O-mold (relative position between the 1 st die and the 2 nd die of the O-mold).

In addition, parameters that can be used instead of the above parameters may be used, and parameters other than the above parameters may be included.

ADVANTAGEOUS EFFECTS OF INVENTION

According to the method for manufacturing a component, the method for manufacturing an automotive component, and the mold in accordance with the aspects of the present invention, it is possible to efficiently manufacture a component having a specific three-dimensional cylindrical portion including at least one of the cross-sectional shape changing portion, the circumferential length change rate changing portion, and the curved portion in the cylindrical portion.

Drawings

Fig. 1A is a diagram illustrating the 1 st mode of the present invention, and is a diagram showing an example of the 1 st model of the 1 st mode.

Fig. 1B is a diagram illustrating an example of a metal plate of the 1 st model according to the 1 st understanding of the present invention.

Fig. 1C is a diagram for explaining the 1 st view of the present invention, and shows an example of the press forming process of the 1 st mold.

Fig. 1D is a view for explaining the 1 st understanding of the present invention, and is a conceptual view showing an example of a press-formed product having an overhang portion during forming in the press-forming step of the 1 st model.

Fig. 1E is a diagram for explaining the 1 st view of the present invention, and is a diagram showing a cross section including a centroid line, which is an example of the press forming process of the 1 st mold.

Fig. 1F is a diagram for explaining the 1 st understanding of the present invention, and shows an example of the contact portion forming step of the 1 st model.

Fig. 1G is a view for explaining the 1 st understanding of the present invention, and is a view showing a cross section including a centroid line of an example of a contact portion forming product of the 1 st mold.

Fig. 2 is a diagram conceptually illustrating the outline of the press forming step and the abutment forming step of the present invention, and the press forming punch width Du and the recess width Do of the O-forming die (abutment forming die) constituting the forming condition ratio a.

Fig. 3A is a diagram for explaining the 2 nd view of the present invention, and is a diagram showing an example of the 2 nd model of the 2 nd view.

Fig. 3B is a diagram for explaining the 2 nd view of the present invention, and shows an example of the metal material plate of the 2 nd model.

Fig. 3C is a diagram for explaining the 2 nd view of the present invention, and shows an example of the press forming process of the 2 nd mold.

Fig. 3D is a diagram for explaining the 2 nd view of the present invention, and is a diagram showing a cross section including a centroid line, which is an example of the press forming process of the 2 nd model.

Fig. 3E is a diagram for explaining the 2 nd view of the present invention, and shows an example of the contact portion forming step of the 2 nd model.

Fig. 3F is a view for explaining the 2 nd view of the present invention, and is a view showing a cross section including a centroid line of an example of a finished product of the abutment portion of the 2 nd mold.

Fig. 4A is a diagram illustrating the 3 rd view of the present invention, and is a diagram showing an example of the 3 rd model of the 3 rd view.

Fig. 4B is a diagram for explaining the 3 rd view of the present invention, and shows an example of the metal material plate of the 3 rd model.

Fig. 4C is a diagram for explaining the 3 rd view of the present invention, and shows an example of the press forming process of the 3 rd mold.

Fig. 4D is a diagram for explaining the 3 rd view of the present invention, and is a diagram showing a cross section including a centroid line, which is an example of the press forming process of the 3 rd model.

Fig. 4E is a diagram for explaining the 3 rd view of the present invention, and shows an example of the contact portion forming step of the 3 rd model.

Fig. 4F is a view for explaining the 3 rd view of the present invention, and is a view showing a cross section including a centroid line of an example of a contact portion forming product of the 3 rd mold.

Fig. 5 is a diagram illustrating an example of the torsion beam assembly according to embodiment 1 of the present invention.

Fig. 6 is a view illustrating a trailing arm according to embodiment 1 of the present invention, and is a perspective view illustrating a trailing arm main body.

Fig. 7A is a diagram illustrating the trailing arm body according to embodiment 1, and is a diagram of the trailing arm body as viewed from the punch side in the press forming direction.

Fig. 7B is a diagram illustrating the trailing arm body according to embodiment 1, and is a diagram of the trailing arm body as viewed from a side orthogonal to the press forming direction.

Fig. 7C is a view illustrating the trailing arm body according to embodiment 1, and is a front closed section of the trailing arm body 100 shown in fig. 7B as viewed from VIIC to VIIC.

Fig. 7D is a view illustrating the trailing arm body according to embodiment 1, and is a rear closed section of the trailing arm body 100 shown in fig. 7B as viewed from VIID-VIID.

Fig. 8 is a flowchart illustrating an example of an outline of the member manufacturing process of the present invention.

Fig. 9 is a flowchart illustrating a manufacturing process of the trailing arm main body according to embodiment 1 of the present invention.

Fig. 10 is a diagram illustrating a schematic configuration of a steel plate used for manufacturing a trailing arm body according to embodiment 1 of the present invention.

Fig. 11A is a diagram illustrating a press forming process in manufacturing the trailing arm main body according to embodiment 1, and is a perspective view showing a schematic configuration of a press forming die.

Fig. 11B is a diagram illustrating a press-forming process in manufacturing the trailing arm main body according to embodiment 1, and is a diagram of the belt excess press-formed product formed in the press-forming process as viewed from the opposite side of the press-forming punch in the press-forming direction.

Fig. 11C is a diagram illustrating a press-forming step in manufacturing the trailing arm main body according to embodiment 1, and is a diagram of a belt excess press-formed product formed in the press-forming step as viewed from a side orthogonal to the press-forming direction.

Fig. 12A is a view for explaining an outline of the trimming process in manufacturing the trailing arm main body according to embodiment 1, and is a perspective view showing an outline configuration of a trimming mold.

Fig. 12B is a diagram for explaining an outline of the trimming process in manufacturing the trailing arm main body according to embodiment 1, and is a diagram of a flangeless press-formed product as viewed from the side opposite to the press-forming punch in the press-forming direction.

Fig. 12C is a diagram illustrating an outline of the trimming step in manufacturing the trailing arm main body according to embodiment 1, and is a diagram of the flangeless press-molded article as viewed from a side orthogonal to the press-molding direction.

Fig. 13A is a view for explaining an outline of a contact portion forming step in manufacturing the trailing arm main body according to embodiment 1, and is a perspective view showing an outline configuration of an O-mold.

Fig. 13B is a diagram for explaining an outline of the contact portion forming step in manufacturing the trailing arm main body according to embodiment 1, and is a diagram of the completed contact portion as viewed from the contact portion side.

Fig. 13C is a diagram for explaining an outline of a contact portion forming step in manufacturing the trailing arm main body according to embodiment 1, and is a diagram of a finished contact portion product viewed from a side orthogonal to a molding direction in forming the contact portion.

Fig. 14 is a diagram illustrating an outline of the molding condition ratio a (Du/Do) of the mold according to embodiment 1 of the present invention.

Fig. 15A is a diagram illustrating an outline of the method of manufacturing the trailing arm body according to embodiment 1 of the present invention, and is a diagram of a state where a steel plate material is placed in a press-forming die as viewed from the front side of the trailing arm body.

Fig. 15B is a diagram for explaining an outline of the method of manufacturing the trailing arm body according to embodiment 1 of the present invention, and is a diagram of a press-formed product and a press-formed product with excess material in a state where the press-forming punch presses the steel material plate against the press-forming die, as viewed from the front side of the trailing arm body.

Fig. 15C is a diagram for explaining an outline of the method of manufacturing the trailing arm main body according to embodiment 1 of the present invention, and is a diagram of a state of the trimmed belt excess material press-formed product and a trimmed flangeless press-formed product as viewed from the front side of the trailing arm main body.

Fig. 15D is a view for explaining an outline of the method of manufacturing the trailing arm main body according to embodiment 1 of the present invention, and is a view of a flangeless press-molded product.

Fig. 15E is a diagram for explaining an outline of the method of manufacturing the trailing arm body according to embodiment 1 of the present invention, and is a diagram of a state in which the flangeless press-molded product is molded into the contact portion forming product by the O-mold, as viewed from the front side of the trailing arm body.

Fig. 15F is a diagram illustrating an outline of the method of manufacturing the trailing arm body according to embodiment 1 of the present invention, and is a diagram of a state in which the contact portion forming product is molded by the O-mold and the molded contact portion forming product, as viewed from the front side of the trailing arm body.

Fig. 15G is a diagram illustrating an outline of the method of manufacturing the trailing arm body according to embodiment 1 of the present invention, and is a diagram of the finished abutment portion as viewed from the front side of the trailing arm body.

Fig. 16A is a diagram for explaining an outline of the method of manufacturing the trailing arm main body according to embodiment 1 of the present invention, and is a diagram of a state where a steel plate material is placed in a press-forming die as viewed from the rear side of the trailing arm main body.

Fig. 16B is a diagram for explaining an outline of the method of manufacturing the trailing arm body according to embodiment 1 of the present invention, and is a diagram of a press-formed product and a press-formed product with excess material in a state where the press-forming punch presses the steel plate material against the press-forming die, as viewed from the rear side of the trailing arm body.

Fig. 16C is a diagram for explaining an outline of the method of manufacturing the trailing arm main body according to embodiment 1 of the present invention, and is a diagram of a trimmed state of the trimmed strip blank press-formed product and a trimmed flangeless press-formed product as viewed from the rear side of the trailing arm main body.

Fig. 16D is a diagram for explaining an outline of the method of manufacturing the trailing arm main body according to embodiment 1 of the present invention, and is a diagram of a state in which the flangeless press-molded product is disposed in the O-mold as viewed from the rear side of the trailing arm main body.

Fig. 16E is a diagram for explaining an outline of the method of manufacturing the trailing arm body according to embodiment 1 of the present invention, and is a diagram of a state in which the flangeless press-molded product is molded into the contact portion forming product by the O-mold, as viewed from the rear side of the trailing arm body.

Fig. 16F is a diagram for explaining an outline of the method of manufacturing the trailing arm body according to embodiment 1 of the present invention, and is a diagram of a state in which the contact portion forming product is molded by the O-mold and the molded contact portion forming product, as viewed from the rear side of the trailing arm body.

Fig. 16G is a diagram for explaining an outline of the method of manufacturing the trailing arm body according to embodiment 1 of the present invention, and is a diagram of the finished abutment portion as viewed from the rear side of the trailing arm body.

Fig. 17A is a diagram illustrating an outline of the method of manufacturing the trailing arm body according to embodiment 2 of the present invention, and is a diagram of a state in which the blank steel plate is pressed by the steel plate pressing member in the press forming die as viewed from the rear side of the trailing arm body.

Fig. 17B is a diagram for explaining an outline of the method of manufacturing the trailing arm body according to embodiment 2 of the present invention, and is a diagram of a state in which the press-forming punch cooperates with the counter punch in the press-forming die to press the steel plate material against the press-forming die for press-forming, as viewed from the rear side of the trailing arm body.

Fig. 17C is a diagram for explaining an outline of the method of manufacturing the trailing arm main body according to embodiment 2 of the present invention, and is a diagram of a state in which a flangeless press-molded product is molded by press molding from a rear side of the trailing arm main body.

Fig. 18A is a diagram for explaining the 1 st mode of the present invention, and shows an example of the 1 st model of the 1 st mode.

Fig. 18B is a diagram for explaining the 1 st understanding of the present invention, and shows an example of the metal material plate of the 1 st model.

Fig. 18C is a diagram for explaining the 1 st mode of the present invention, and shows an example of the bending step of the 1 st mold.

Fig. 18D is a view for explaining the 1 st understanding of the present invention, and is a view showing a cross section including a centroid line of an example of a bent molded product of the 1 st model.

Fig. 18E is a diagram for explaining the 1 st understanding of the present invention, and shows an example of the contact portion forming step of the 1 st model.

Fig. 18F is a view for explaining the 1 st understanding of the present invention, and is a view showing a cross section including a centroid line of an example of a contact portion forming product of the 1 st mold.

Fig. 19 is a diagram conceptually illustrating the outline of the bending step and the abutment portion forming step of the present invention, and the bending punch width Du and the recess width Do of the O-die constituting the molding condition ratio a.

Fig. 20A is a diagram for explaining the 2 nd view of the present invention, and is a diagram showing an example of the 2 nd model of the 2 nd view.

Fig. 20B is a diagram for explaining the 2 nd view of the present invention, and shows an example of the metal material plate of the 2 nd model.

Fig. 20C is a diagram for explaining the 2 nd view of the present invention, and shows an example of the bending step of the 2 nd mold.

Fig. 20D is a view for explaining the 2 nd view of the present invention, and is a view showing a cross section including a centroid line of an example of a bent molded product of the 2 nd model.

Fig. 20E is a diagram for explaining the 2 nd view of the present invention, and shows an example of the contact portion forming step of the 2 nd model.

Fig. 20F is a view for explaining the 2 nd view of the present invention, and is a view showing a cross section including a centroid line of an example of a finished product of the abutment portion of the 2 nd mold.

Fig. 21A is a diagram for explaining the 3 rd view of the present invention, and is a diagram showing an example of the 3 rd model of the 3 rd view.

Fig. 21B is a diagram for explaining the 3 rd view of the present invention, and shows an example of the metal material plate of the 3 rd model.

Fig. 21C is a diagram for explaining the 3 rd view of the present invention, and shows an example of the bending step of the 3 rd mold.

Fig. 21D is a view for explaining the 3 rd view of the present invention, and is a view showing a cross section including a centroid line of an example of a 3 rd model bend-molded product.

Fig. 21E is a diagram for explaining the 3 rd view of the present invention, and shows an example of the contact portion forming step of the 3 rd model.

Fig. 21F is a view for explaining the 3 rd view of the present invention, and is a view showing a cross section including a centroid line of an example of a contact portion forming product of the 3 rd mold.

Fig. 22 is a flowchart illustrating an example of an outline of the member manufacturing process of the present invention.

Fig. 23 is a flowchart illustrating a manufacturing process of the trailing arm main body according to the embodiment of the present invention.

Fig. 24 is a view illustrating a schematic configuration of a steel plate used for manufacturing a trailing arm body according to an embodiment of the present invention.

Fig. 25A is a view illustrating a bending step in manufacturing the trailing arm main body according to the embodiment, and is a perspective view showing a schematic configuration of a bending mold.

Fig. 25B is a view for explaining an outline of a bent molded article molded in the bending step of the embodiment, and is a view of the bent molded article as viewed from the side opposite to the bending punch in the bending direction.

Fig. 25C is a view for explaining an outline of a bent molded article molded in the bending step according to the embodiment, and is a view of the bent molded article as viewed from a side orthogonal to the bending direction.

Fig. 26A is a schematic view illustrating a contact portion forming step in manufacturing the trailing arm main body according to the embodiment, and is a perspective view showing a schematic configuration of an O-mold.

Fig. 26B is a diagram illustrating an outline of the contact portion forming product connected in the contact portion forming step of the embodiment, and is a diagram of the contact portion forming product viewed from the contact portion side.

Fig. 26C is a diagram illustrating an outline of the abutment portion forming product that is abutted in the abutment portion forming step of the embodiment, and is a diagram of the abutment portion forming product viewed from a side orthogonal to the molding direction in the abutment portion forming.

Fig. 27 is a diagram illustrating an outline of a molding condition ratio a (Du/Do) of a mold according to an embodiment of the present invention.

Fig. 28A is a diagram illustrating an outline of a method of manufacturing the trailing arm main body according to the embodiment of the present invention, and is a diagram of a state where a steel plate material is placed in a bending mold as viewed from the front side of the trailing arm main body.

Fig. 28B is a view for explaining an outline of a method for manufacturing the trailing arm main body according to the embodiment of the present invention, and is a view for viewing a state in which the bending punch presses the steel material plate against the bending die and bends the formed product, from the front side of the trailing arm main body.

Fig. 28C is a diagram for explaining an outline of a method for manufacturing the trailing arm main body according to the embodiment of the present invention, and is a diagram of a state in which a bent molded article is arranged in the O-mold as viewed from the front side of the trailing arm main body.

Fig. 28D is a view for explaining an outline of a method of manufacturing the trailing arm body according to the embodiment of the present invention, and is a view of a state in which a curved molded product is formed into a closed cross section by an O-mold and an abutment portion formed product is molded, as viewed from the front side of the trailing arm body.

Fig. 28E is a diagram for explaining an outline of the method of manufacturing the trailing arm body according to the embodiment of the present invention, and is a diagram of a state in which the contact portion forming product is molded by the O-mold and a diagram of the contact portion forming product after molding, as viewed from the front side of the trailing arm body.

Fig. 28F is a view for explaining an outline of a method of manufacturing the trailing arm body according to the embodiment of the present invention, and is a view of the trailing arm body formed by joining the contact portions of the contact portion forming products as viewed from the front side.

Fig. 29A is a diagram illustrating an outline of a method of manufacturing the trailing arm main body according to the embodiment of the present invention, and is a diagram of a state where a steel plate material is placed in a bending mold as viewed from the rear side of the trailing arm main body.

Fig. 29B is a diagram for explaining an outline of a method for manufacturing the trailing arm body according to the embodiment of the present invention, and is a diagram for illustrating a state in which a steel plate material is pressed against a bending die by a bending punch and bent and a bent product, as viewed from the rear side of the trailing arm body.

Fig. 29C is a view for explaining an outline of a method of manufacturing the trailing arm main body according to the embodiment of the present invention, and is a view showing a state where a bent molded product is placed on the O-mold as viewed from the rear side of the trailing arm main body.

Fig. 29D is a diagram for explaining an outline of a method of manufacturing the trailing arm body according to the embodiment of the present invention, and is a diagram of a state in which a curved molded product is formed into a closed section by an O-mold and an abutment portion formed product is molded, as viewed from the rear side of the trailing arm body.

Fig. 29E is a diagram for explaining an outline of the method of manufacturing the trailing arm body according to the embodiment of the present invention, and is a diagram of a state in which the contact portion forming product is molded by the O-mold and the molded contact portion forming product, as viewed from the rear side of the trailing arm body.

Fig. 29F is a diagram for explaining an outline of a method of manufacturing the trailing arm body according to the embodiment of the present invention, and is a diagram of the trailing arm body formed by joining the contact portions of the contact portion forming products as viewed from the rear side.

Detailed Description

The present inventors have intensively studied a technique for efficiently manufacturing a member applicable to an automobile member or the like having a cylindrical portion as shown in (1) to (3) below by applying a cylindrical portion forming method for forming a cylindrical portion from a metal material plate. (1) At a circumferential length change part where the circumferential length of a cross section (cross section orthogonal to the longitudinal direction) orthogonal to the shape center line changes along the shape center line, a circumferential length change rate change part (2) where the rate of change of the circumferential length changes and a cross section shape change part (3) where the shape of the cross section orthogonal to the shape center line changes along the shape center line have a curved part of curvature.

As a result, the following findings 1 to 6 were obtained. In the present embodiment, the numerical range indicated by the term "to" refers to a range including numerical values before and after the term "to" as a lower limit value and an upper limit value.

[ 1 st finding ]

The 1 st view is a view related to the circumferential length change rate changing unit.

The 1 st view of the present invention will be described below with reference to fig. 1A to 1F and fig. 2. Fig. 1A to 1F and fig. 2 are views for explaining the 1 st understanding of the present invention. In fig. 1D, 1E, and 1G, arrows facing each other indicate compressive strain, and arrows facing opposite sides indicate tensile strain.

The 1 st view is an example of a component model (hereinafter, referred to as a 1 st model) M100, for example, which includes, as shown in fig. 1A: a conical shape portion M101 having a circular closed cross section when viewed from the axis (shape line) direction, the circumference of the closed cross section gradually changing at a constant rate of change along the shape line; a linear portion M102 having a circular cross section and connected to the smaller diameter side of the conical portion M101; and a circumferential length change rate changing portion M103 formed at a connecting portion between the conical portion M101 and the linear portion M102, and changing the circumferential length change rate.

The first model M100 is formed by molding a metal material sheet W100 as shown in fig. 1B in the order of a press molding step, a flangeless molding step, and an O-molding step (contact portion forming step). In the O-molding step, for example, a flangeless press-molded article (U-molded article) in which side end portions are formed in the press-molding step is used. Note that, although an example of forming the 1 st model M100 by press forming (drawing) is described here, the same idea holds true when the 1 st model M100 is formed by bending. The bending process will be described later.

The metal plate W100 includes a fan-shaped portion W101 corresponding to the conical portion M101, a rectangular portion W102 corresponding to the linear portion M102, and a connecting portion W103 corresponding to the circumferential length change rate changing portion M103.

In the press forming step, as shown in fig. 1C, a press-formed product is formed using a press forming die (U-forming die) D110 including a press forming die D111, a press forming punch D112, and a metal plate pressing tool D113. The left side view of fig. 1C is a side view of the press-forming die D110 and the metal material plate W100 provided in the press-forming die D110, and the right side view is a right side view of these components (a view of the structure of the left side view is viewed from the right side).

The press-forming die D111 has a press-forming concave portion D111A, and the press-forming concave portion D111A has a lower-side formed shape portion corresponding to a final shape of the 1 st model M100 within a range of approximately 180 ° (lower half) with respect to the centroid line when viewed from the centroid line direction of the 1 st model M100, and an upper-side formed shape portion which is continuous with the lower-side formed shape portion and is formed by extending an upper end of the lower-side formed shape portion upward.

The press-forming punch D112 is formed with a press-forming convex portion D112A, and the press-forming convex portion D112A is configured to correspond to the inner peripheral surface of the press-formed product with a predetermined gap from the press-forming concave portion D111A.

The metal material plate pressing tool D113 presses the metal material plate W100 disposed across the press-forming concave portion D111A to the press-forming die D111 at the outer sides of both sides of the press-forming concave portion D111A by the metal material plate pressing tool D113 at the time of press-forming.

Next, the press punch D112 is advanced (lowered), and the metal material plate W100 is inserted into the press die D111. At this time, the portion of the metal material W100 pressed by the metal material pressing tool D113 applies a tensile force to the portion to be molded.

As a result, as shown in fig. 1D, a member (intermediate product of the press-formed product) M110A is formed in the press-forming die D111, and this member M110A has a concave portion (concave portion in cross-sectional view) that opens on the side of the press-forming punch D112 and is concave toward the press-forming die D111, and has a protruding portion M110B that protrudes outward from the press-forming concave portion D111A. In addition, the left view of fig. 1D is a side view of the member M110A, and the right view is a right side view of the member M110A (a view of the structure of the left view as viewed from the right side).

Subsequently, the press-forming punch D112 is further advanced (lowered) (flangeless process), and the protruding portion M110B is inserted into the press-forming die D111, thereby forming a flangeless press-formed product M110 without a protruding portion as shown in fig. 1E. The flangeless press-formed product M110 has a portion M111 corresponding to the conical portion M101, a portion M112 corresponding to the linear portion M102, and a portion M113 corresponding to the circumferential length change rate changing portion M103. In this example, the flangeless process is part of the press forming process.

In the press forming step, as shown in fig. 1D and 1E, a compressive strain is generated in a portion M113 corresponding to the circumferential length change rate changing portion M103. The flangeless process may be a process of inserting the protruding portion into the press-molding die as described above, or may be a process of trimming the protruding portion as described in embodiment 1 described below.

In the O-molding step, as shown in fig. 1F, an O-molding step is performed using an O-mold D120. Specifically, the 1 st mold M100 is formed by bringing the side end portions M110E of the portions to be abutted of the flangeless press-formed product M110 into contact with each other to form the abutting portions M100C by the lower mold (1 st die) D121 in which the lower mold recessed portion D121A is formed and the upper mold (2 nd die) D122 in which the upper mold recessed portion D122A is formed along the side end portion M110E of the portion to be abutted. The left drawing of fig. 1F is a side view of the lower die D121, the upper die D122, and the flangeless press-molded product M110 disposed therebetween, and the right drawing is a right side view of these components (a view of the structure of the left drawing is viewed from the right side).

In the contact portion forming step, as shown in fig. 1G, tensile strain is generated in the contact portion M100C of the circumferential length change rate changing portion M103.

Here, the change in the circumferential length change rate between the 1 st end and the 2 nd end of the circumferential length change rate changing portion M103 may be 0.035 to 0.35. Here, the 1 st end may be one end in the longitudinal direction of the circumferential length change rate changing portion M103, and the 2 nd end may be the other end. The change (value) of the circumferential length change rate between the 1 st end portion and the 2 nd end portion of the circumferential length change rate changing portion M103 is defined by a value (absolute value) obtained by dividing the difference in the circumferential length change rate between the 1 st end portion (starting point) and the 2 nd end portion (ending point) of the circumferential length change rate changing portion by the interval (length, size) between the 1 st end portion and the 2 nd end portion along the centroid line. The circumferential length change rate can be calculated based on, for example, a curved surface shape measured by a shape measuring device or data measured by another measuring method.

Next, the concept of the molding condition ratio a and the method of calculating the molding condition ratio a will be described with reference to fig. 2.

Fig. 2 is a diagram conceptually showing an outline of the press forming process, an outline of the O-forming process, and a press forming punch width Du constituting the forming condition ratio a and a recess width (width of the contact portion forming recess) Do of the O-forming die.

As shown in fig. 2, in the press-forming step, the metal material plate is pressed against the press-forming die by the metal material pressing tool, and the press-formed product (press-formed portion) is press-formed by the press-forming punch, thereby forming the cylindrical portion, which is known as a cost. Thereafter, the press-formed product is trimmed to form a flangeless press-formed product. Next, in the O-molding step, the side end portion of the flangeless press-molded product (side end portion forming press-molded portion) is molded so as to be along the concave portion of the O-molding die (1 st die and 2 nd die), and thereby the side end portion (end portions on both sides in the cross section, that is, the portion to be abutted) of the flangeless press-molded product is abutted.

As shown in fig. 2, the molding condition ratio a is a numerical value defined by a ratio (Du/Do) of a width Du of a press-forming convex portion of a press-forming punch that presses a metal material against a press-forming die in a press-forming die that performs press-forming in a press-forming step, to a width Do of a concave portion of a contact-portion-forming concave portion of an O-forming die (1 st die and 2 nd die) used in an O-forming step.

In this case, the molding condition ratio a is 0.85 to 0.95 (see 4 th finding). By setting the molding condition ratio a to a value within such a range, the portions to be abutted by the circumferential length change rate changing portion M103 can be brought into close contact with each other with high accuracy in the O-molding step, and the 1 st mold M100 having the circumferential length change rate changing portion M103 can be manufactured efficiently. The molding condition ratio a of the mold corresponding to at least the specific three-dimensional cylindrical portion (here, the circumferential length change rate changing portion M103) may be 0.85 or more and 0.95 or less. The molding condition ratio a may be set to 0.85 or more and 0.95 or less over the entire region of the mold. The same applies to other findings and embodiments described later.

When the molding condition ratio a is less than 0.85, the strain generated in the press-molding step and the O-molding step becomes excessively large, and the spring-back of the circumference length change rate changing portion M103 becomes excessively large. Therefore, the closed cross section (cross section orthogonal to the longitudinal direction) of the circumferential length change rate changing portion M103 becomes a vertically long oval shape greatly deviating from the target shape (here, a perfect circle), and the roundness is reduced. When the molding condition ratio a exceeds 0.95, the side end portions of the circumferential variation rate changing portion M103 formed in the O-molding step do not sufficiently come into close contact or approach each other.

The 1 st model M100 including the circumferential length change rate changing portion M103 may have various shapes. Therefore, depending on the shape of the 1 st mold M100, the preferable range of the molding condition ratio a may be in the range of 0.85 to 0.95. In order to find such a preferable molding condition ratio a, the following process may be performed before the U-molding step (here, the press-molding step).

That is, the molding condition ratio setting step is performed in 1 or more cycles before the U molding step, and a preferable molding condition ratio a is set. Here, the molding condition ratio setting step performs finite element analysis in consideration of the molding condition ratio a set in the molding condition ratio setting step of the previous cycle (an initial value of the molding condition ratio a set in advance in the case of the first cycle), the material characteristics of the component, the shape and the plate thickness of the metal material plate, the molding condition in the U molding step, and the molding condition in the O molding step. Thus, shape parameters including the amount of strain in the direction along the centroid line of the specific three-dimensional cylindrical portion (here, the circumferential length change rate changing portion M103) due to the U-forming process, the amount of strain in the direction along the centroid line of the specific three-dimensional cylindrical portion (here, the circumferential length change rate changing portion M103) due to the O-forming process, and the relative positions of the side end portions (portions to be abutted) are estimated.

Here, the material properties of the member mean young's modulus, yield strength (proof stress), relationship between stress and strain in a tensile test (stress-strain curve, etc.), and the like of the material constituting the member.

The shape and the thickness of the metal plate are the shape and the thickness of the metal plate formed in accordance with the member and the specific three-dimensional cylindrical portion (here, the circumferential length change rate changing portion M103).

The forming conditions in the U forming step (herein, the press forming step) include, for example, the width Du of the U forming punch (herein, the press forming punch), the shape of the forming die (herein, the press forming die), the forming load in the U forming step, and the displacement of the U forming punch with respect to the forming die (the relative position between the press forming die and the press forming punch) in the U forming step.

The molding conditions in the O-molding step are the shape of the concave portion formed by the contact portion of the O-mold (including the concave portion width Do), the molding load in the O-molding step, or the displacement of the 2 nd die with respect to the 1 st die in the O-mold (relative position between the 1 st die and the 2 nd die of the O-mold). Parameters other than these may of course also be considered.

Then, the molding condition ratio setting step is repeated until the estimated shape parameters satisfy the desired conditions. Here, the desired conditions may be set in various ways depending on the characteristics (strength, dimensional accuracy, and the like) required for the specific three-dimensional cylindrical portion. In any case, when a member having a specific three-dimensional cylindrical portion is manufactured, by setting the molding condition ratio a to be in the range of 0.85 to 0.95, the portions to be abutted by the specific three-dimensional cylindrical portion can be brought into close contact with each other with high accuracy, and further, a member having a specific three-dimensional cylindrical portion can be manufactured efficiently.

The 1 st finding can also be applied to bending. An example in which the 1 st finding of the present invention is applied to bending is described below with reference to fig. 18A to 18F and fig. 19. Fig. 18A to 18F and fig. 19 are diagrams for explaining an example in which the 1 st finding of the present invention is applied to bending. In fig. 18D and 18F, arrows facing each other indicate compressive strain, and arrows facing opposite sides indicate tensile strain.

The 1 st finding is an example of a component model (hereinafter, referred to as a 1 st model) M100 ', for example, and as shown in fig. 18A, the component model M100' includes: a conical shape portion M101' having a circular closed cross section when viewed from the axis (shape line) direction, the circumference of the closed cross section gradually changing at a constant rate of change along the shape line; a linear portion M102 'having a circular cross section and connected to the smaller diameter side of the conical portion M101'; and a circumferential length change rate changing portion M103 ' formed at a connecting portion between the conical portion M101 ' and the linear portion M102 ', and changing the circumferential length change rate.

The metal material plate W100 shown in fig. 18B is formed in the order of the bending step and the O-forming step (contact portion forming step), thereby forming a 1 st mold M100'.

The metal plate W100 ' includes a fan-shaped portion W101 ' corresponding to the conical portion M101 ', a rectangular portion W102 ' corresponding to the linear portion M102 ', and a connecting portion W103 ' corresponding to the circumferential length change rate changing portion M103 '.

In the bending step, as shown in fig. 18C, a bent product M110 'is molded using a bending die (U-die) D110' including a bending die D111 'and a bending punch D112'. In addition, the left side view of fig. 18C is a side view of the bending die D110 ' and the metal material plate W100 ' provided in the bending die D110 ', and the right side view is a right side view of these components (a view of the structure of the left side view is viewed from the right side).

The bending die D111 ' is formed with a bending recess D111A ', and the bending recess D111A ' has a lower molded shape portion corresponding to a final shape of the 1 st model M100 ' within a range of approximately 180 ° from the shape center line (lower half) and an upper molded shape portion connected to the lower molded shape portion and formed by extending an upper end of the lower molded shape portion upward, when viewed from the shape center line direction of the 1 st model M100 '.

The bending punch D112 ' is formed with a bending convex portion D112A ', and the bending convex portion D112A ' is formed to correspond to the inner peripheral surface of the bending product M110 ' with a predetermined interval from the bending concave portion D111A '.

Next, the bending punch D112 'is advanced (lowered), and the metal material sheet W100' placed in the bending recess D111A 'is inserted into the bending die D111'.

As a result, as shown in fig. 18D, a member (bent product) M110 'is formed, and the member M110' is formed with a concave portion which opens to the bending punch D112 'side and is concave toward the bending die D111' side.

In the bending step, compressive strain as shown in fig. 18D is generated on the concave portion side of the portion M113 'corresponding to the circumferential length change rate changing portion M103'. The bent molded article M110 ' has a portion M111 ' corresponding to the conical portion M101 ', a portion M112 ' corresponding to the linear portion M102 ', and a portion M113 ' corresponding to the circumferential length change rate changing portion M103 '.

In the O-molding step, as shown in fig. 18E, an O-molding step is performed using an O-molding die D120'. Specifically, the 1 st mold M100 ' is formed by bringing the side end portions M110E ' of the to-be-contacted portion of the bent molded article M110 ' into contact with each other to form the contact portion M100C ' by the lower mold (1 st cavity) D121 ' in which the lower mold recess D121A ' is formed and the upper mold (2 nd cavity) D122 ' in which the upper mold recess D122A ' is formed along the side end portion M110E ' of the to-be-contacted portion. The left side view of fig. 18E is a side view of the lower mold D121 ', the upper mold D122 ', and the bent molded article M110 ' disposed therebetween, and the right side view thereof (a view of the structure of the left side view as viewed from the right side).

In the O-molding step, tensile strain as shown in fig. 18F is generated in the contact portion M100C of the circumference length change rate changing portion M103.

Next, the concept of the molding condition ratio a and the method of calculating the molding condition ratio a will be described with reference to fig. 19A.

Fig. 19 is a diagram conceptually showing the outline of the bending step and the O-forming step of the present invention, and the bending punch width Du constituting the forming condition ratio a and the recess width Do of the O-forming die (the width of the abutting portion forming the recess).

As shown in fig. 19, the bent product (bent portion) bent in the bending step is formed so as to follow the concave portion of the O-mold (the 1 st concave die and the 2 nd concave die) in the O-molding step, thereby forming a cylindrical portion which is obvious in cost. Thereby, the side end portions (end portions on both sides in the cross section) of the bent molded article (bent molded portion) are brought into contact.

As shown in fig. 19, the molding condition ratio a is a numerical value defined by a ratio (Du/Do) of a width Du of a bending convex portion of a bending punch pressing a metal material against a bending die in a bending die for bending in a bending step to a width Do of a contact portion forming concave portion of an O-die (1 st die and 2 nd die) used in an O-forming step.

The molding condition ratio a is 0.85 to 0.95 (see fig. 4) as in the case of press molding. By setting the molding condition ratio a to a value within such a range, the portion to be abutted by the circumferential length change rate changing portion M103 ' can be brought into close contact with each other with high accuracy in the O-molding step, and the 1 st mold M100 ' having the circumferential length change rate changing portion M103 ' can be manufactured efficiently. The molding condition ratio a of the mold corresponding to at least the entire length or a part of the specific three-dimensional cylindrical portion (here, the circumferential length change rate changing portion M103') may be 0.85 or more and 0.95 or less. The molding condition ratio a may be set to 0.85 or more and 0.95 or less over the entire region of the mold.

When the molding condition ratio a is less than 0.85, the strain generated in the bending step and the O-molding step becomes excessively large, and the spring back of the circumference length change rate changing portion M103' becomes excessively large. Therefore, the closed cross section (cross section orthogonal to the longitudinal direction) of the circumferential length change rate changing portion M103' becomes a vertically long oval shape greatly deviating from the target shape (here, a perfect circle), and the roundness is reduced. When the molding condition ratio a exceeds 0.95, the side end portions of the circumferential variation rate changing portion M103' formed in the O-molding step do not sufficiently come into close contact or approach each other.

The 1 st model M100 'including the circumferential length change rate changing portion M103' can have various shapes. Therefore, depending on the shape of the 1 st mold M100', the preferable range of the molding condition ratio a may be in the range of 0.85 to 0.95. Therefore, as described above, the preferable molding condition ratio a can also be found by finite element analysis. The specific treatment method is as described above.

Examples of parameters to be considered here include material characteristics of the member, shape and thickness of the metal material plate, molding conditions in the bending step, and molding conditions in the O-molding step. The material characteristics of the member, the shape and thickness of the metal material plate, and the molding conditions in the O-molding step are as described above. The forming conditions in the bending step include, for example, the width Du of the bending punch, the shape of the bending die, the forming load in the bending step, or the displacement of the bending punch relative to the bending die in the bending step (the relative position between the bending die and the bending punch).

[ finding 2 ]

The 2 nd finding is a finding about the cross-sectional shape changing portion.

The following describes the 2 nd view of the present invention with reference to fig. 3A to 3D. Fig. 3A to 3D are views for explaining the 2 nd view of the present invention. In fig. 3D and 3F, arrows facing each other indicate compressive strain, and arrows facing opposite sides indicate tensile strain.

The 2 nd view is an example of a component model (hereinafter, referred to as a 2 nd model) M200, for example, and as shown in fig. 3A, the component model M200 includes a rectangular closed cross section M201 having a rectangular shape when viewed from the axial line (centroid line) direction, a circular closed cross section M202 having a circular shape, and a cross-sectional shape changing portion M203 formed between the circular closed cross section and the rectangular closed cross section and having a shape gradually changing along the centroid line.

The 2 nd model M200 is formed by molding a rectangular metal material plate W200 as shown in fig. 3B in the order of a press molding step, a flangeless molding step, and an O-molding step (contact portion forming step). Note that, although an example of forming the 2 nd model M200 by press forming is described here, the same idea holds true in the case of forming the 2 nd model M200 by bending forming. The bending process will be described later.

In the press-forming step, as shown in fig. 3C, a press-formed product is formed using a press-forming die (U-forming die) D210 including a press-forming die D211, a press-forming punch D212, and a metal plate pressing tool D213. The left side of fig. 3C is a side view of the press-forming die D210 and the metal material plate W200 provided in the press-forming die D210, and the right side is a right side view of these components (a view of the structure of the left side is viewed from the right side).

The press-forming die D211 is formed with a press-forming concave portion D211A, and the press-forming concave portion D211A has a lower-side formed shape portion corresponding to a final shape of the 2 nd model M200 within a range of approximately 180 ° (lower half) with respect to the centroid line, and an upper-side formed shape portion which is continuous with the lower-side formed shape portion and is formed by extending an upper end of the lower-side formed shape portion upward, when viewed from the centroid line direction of the 2 nd model M200. The press-forming punch D212 is formed with a press-forming convex portion D212A, and the press-forming convex portion D212A is configured to correspond to the inner peripheral surface of the press-formed product with a predetermined gap from the press-forming concave portion D211A.

The metal material plate pressing tool D213 presses the metal material plate W200 to the press-forming die D211 on both sides across the press-forming concave portion D211A during press-forming.

Then, the metal material plate W200 is press-formed by the press-forming punch D212 and the press-forming die D211, thereby forming a press-formed product in which the side of the press-forming punch D212 opens and the side of the press-forming die D211 becomes a concave portion.

In the press forming step, compressive and tensile strains as shown in fig. 3D are generated on the concave portion side of the portion M213 corresponding to the cross-sectional shape changing portion M203. Further, reference numeral M210 denotes a flangeless press-molded product. The flangeless press-formed product M210 has a portion M211 corresponding to the rectangular closed cross section M201, a portion M212 corresponding to the circular closed cross section M202, and a portion M213 corresponding to the cross-sectional shape changing portion M203.

In the O-molding step, as shown in fig. 3E, an O-molding step is performed using an O-mold D220. Specifically, the 2 nd mold M200 is formed by bringing the side end portions M210E of the portions to be abutted of the flangeless press-formed product M210 into contact with each other to form the abutting portions M200C by the lower mold (1 st die) D221 formed with the lower mold recess D221A and the upper mold (2 nd die) D222 formed with the upper mold recess D222A along the side end portion M210E of the portion to be abutted. The left drawing of fig. 3E is a side view of the lower die D221, the upper die D222, and the flangeless press-molded product M210 disposed therebetween, and the right drawing is a right side view of these components (a view of the structure of the left drawing is viewed from the right side).

In the O-molding step, compressive and tensile strains as shown in fig. 3F are generated on the contact portion M200C side of the cross-sectional shape changing portion M203.

Here, the change in the sectional shape of the section shape changing portion M203 (the shape of the section shape changing portion M203 orthogonal to the centroid) along the centroid line in the direction including the centroid line and the contact portion M200C (i.e., the length of the line segment that passes through the centroid of the section and the contact portion M200C and intersects the outer periphery of the section) may be 10% to 50%. The change in the sectional shape of the sectional shape changing portion M203 is represented by a numerical value (percentage) obtained by dividing the difference between the lengths of the sectional shapes at two arbitrary points set along the centroid line in the direction including the centroid line and the contact portion M200C by the length along the centroid line between the two points.

In such press forming, the forming condition ratio a is also 0.85 to 0.95 (see fig. 4). By setting the molding condition ratio a to a value within such a range, the portion to be abutted by the cross-sectional shape varying portion M203 can be brought into close contact with high accuracy in the O-molding step, and the 2 nd mold M200 having the cross-sectional shape varying portion M203 can be efficiently manufactured. The molding condition ratio setting step may be performed in 1 or more cycles to find a preferable range of the molding condition ratio a.

The 2 nd finding can also be applied to the bending forming process. An example in which the finding 2 of the present invention is applied to the bending process will be described below with reference to fig. 20A to 20D. Fig. 20A to 20D are diagrams for explaining an example in which the finding 2 of the present invention is applied to bending. In fig. 20D and 20F, arrows facing each other indicate compressive strain, and arrows facing opposite sides indicate tensile strain.

The 2 nd view is an example of a component model (hereinafter, referred to as a 2 nd model) M200 ', for example, and as shown in fig. 20A, the component model M200 ' includes a rectangular closed cross section M201 ' having a rectangular shape, a circular closed cross section M202 ' having a circular shape, and a cross-sectional shape changing portion M203 ' formed between the circular closed cross section and the rectangular closed cross section and having a shape gradually changing along a centroid line.

The 2 nd model M200 'is formed by molding a rectangular metal material plate W200' as shown in fig. 20B in the order of the bending molding step and the O molding step (abutting portion forming step).

In the bending step, as shown in fig. 20C, a bent product M210 'is molded using a bending die (U-die) D210' including a bending die D211 'and a bending punch D212'. In addition, the left view of fig. 20C is a side view of the bending die D210 ' and the metal material plate W200 ' provided in the bending die D210 ', and the right view is a right side view of these components (a view of the structure of the left view is viewed from the right side).

The bending die D211 ' is formed with a bending concave portion D211A ', and the bending concave portion D211A ' has a lower molded shape portion corresponding to a final shape of the 2 nd model M200 ' within a range of approximately 180 ° (lower half) with respect to the shape axis, and an upper molded shape portion which is continuous with the lower molded shape portion and is formed by extending an upper end of the lower molded shape portion upward, when viewed from the shape axis direction of the 2 nd model M200 '. The bending punch D212 ' is formed with a bending convex portion D212A ', and the bending convex portion D212A ' is configured to correspond to the inner peripheral surface of the bent product M210 ' with a predetermined interval from the bending concave portion D211A '.

Then, the metal material plate W200 'is bent by the bending punch D212' and the bending die D211 ', thereby forming a bent product M210' in which the side of the bending punch D212 'is open and the side of the bending die D211' is a concave portion.

In the bending step, compressive and tensile strains as shown in fig. 20D are generated on the concave portion side of the portion M213 'corresponding to the cross-sectional shape changing portion M203'. The flangeless press-formed product M210 ' has a portion M211 ' corresponding to the rectangular closed cross section M201 ', a portion M212 ' corresponding to the circular closed cross section M202 ', and a portion M213 ' corresponding to the cross-sectional shape changing portion M203 '.

In the O-molding step, as shown in fig. 20E, an O-molding step is performed using an O-molding die D220'. Specifically, the 2 nd mold M200 'is formed by bringing the side end portions M210E' of the to-be-contacted portion of the bent molded article M210 'into contact with each other to form the contact portion M200C' by the lower mold (1 st cavity) D221 formed with the lower mold recess D221A 'and the upper mold (2 nd cavity) D222' formed with the upper mold recess D222A 'along the side end portion M210E' of the to-be-contacted portion. The left view of fig. 20E is a side view of the lower mold D221 ', the upper mold D222 ', and the bent molded article M210 ' disposed therebetween, and the right view is a right side view of these components (a view of the structure of the left view is viewed from the right side).

In the O-molding step, compressive and tensile strains as shown in fig. 20F are generated on the contact portion M200C 'side of the cross-sectional shape changing portion M203'.

Here, the change in the sectional shape of the cross-sectional shape changing portion M203 ' (the shape of the cross-section of the cross-sectional shape changing portion M203 ' orthogonal to the centroid) along the centroid line in the direction including the centroid line and the contact portion M200C ' (i.e., the length of the line segment that passes through the centroid of the cross-sectional shape changing portion M203 ' and intersects the outer periphery of the cross-sectional shape changing portion M200C ') may be 10% to 50%. The change in the sectional shape of the sectional shape changing portion M203 'is represented as a numerical value (percentage) obtained by dividing the difference between the lengths of the sectional shapes at two arbitrary points set along the centroid line in the direction including the centroid line and the abutting portion M200C' by the length along the centroid line between the two points.

In such bending, the molding condition ratio a is also 0.85 to 0.95 (see 4 th finding). By setting the molding condition ratio a to a value within such a range, the portion to be abutted by the cross-sectional shape changing portion M203 ' can be brought into close contact with each other with high accuracy in the O-molding step, and the 2 nd mold M200 ' having the cross-sectional shape changing portion M203 ' can be manufactured efficiently. The molding condition ratio setting step may be performed in 1 or more cycles to find a preferable range of the molding condition ratio a.

[ 3 rd finding ]

The 3 rd finding is a finding related to the bending portion.

The following describes the 3 rd view of the present invention with reference to fig. 4A to 4D. Fig. 4A to 4D are diagrams for explaining the 3 rd view of the present invention. In fig. 4D and 4F, arrows facing each other indicate compressive strain, and arrows facing opposite sides indicate tensile strain.

For example, as shown in fig. 4A, the 3 rd finding is an example of a part model (hereinafter, referred to as the 3 rd model) M300 having a curved portion in which a circular closed cross section is curved in a curved shape in a molding direction.

The 3 rd mold M300 is formed by molding a rectangular metal material plate W300 as shown in fig. 4B in the order of a press molding step, a flangeless molding step, and an O-molding step (contact portion forming step). Note that, although an example of forming the 3 rd model M300 by press forming is described here, the same idea holds true in the case of forming the 3 rd model M300 by bending forming. The bending process will be described later.

In the press-forming step, as shown in fig. 4C, a press-formed product is formed using a press-forming die D (U-forming die) 310 provided with a press-forming die D311, a press-forming punch D312, and a metal plate pressing tool D313. The left drawing of fig. 4C is a side view of the press-forming die D310 and the metal material plate W300 disposed in the press-forming die D310, and the right drawing is a cross-sectional view of these members perpendicular to the longitudinal direction.

The press-forming die D311 is formed with a press-forming concave portion D311A, and the press-forming concave portion D311A has a lower-side formed shape portion corresponding to a final shape of the 3 rd model M300 within a range of approximately 180 ° (lower half) with respect to the shape axis and an upper-side formed shape portion connected to the lower-side formed shape portion and formed by extending an upper end of the lower-side formed shape portion upward, when viewed from the shape axis direction of the 3 rd model M300. The press-forming punch D312 is formed with a press-forming convex portion D312A, and the press-forming convex portion D312A is configured to correspond to the inner peripheral surface of the press-formed product with a predetermined gap from the press-forming concave portion D311A.

The metal material plate pressing tool D313 presses the metal material plate W300 to the press-forming die D311 on both sides across the press-forming recessed portion D311A during press forming.

Then, the metal material plate W300 is press-formed by the press-forming punch D312 and the press-forming die D311, whereby a press-formed product is formed in which the side of the press-forming punch D312 opens and the side of the press-forming die D311 becomes a concave portion.

In the press-forming step, compressive strain as shown in fig. 4D is generated on the concave portion side of the press-formed product M310. Further, a reference numeral M310 denotes a flangeless press-molded product.

In the O-molding step, as shown in fig. 4E, an O-molding step is performed using an O-mold D320. Specifically, the 3 rd mold M300 is formed by bringing the side end portions M310E of the portions to be abutted of the flangeless press-formed product M310 into contact with each other to form the abutting portions M300C by the lower mold (1 st die) D321 in which the lower mold recessed portion D321A is formed and the upper mold (2 nd die) D322 in which the upper mold recessed portion D322A is formed along the side end portion M310E of the portion to be abutted. The left drawing of fig. 4E is a side view of the lower die D321, the upper die D322, and the flangeless press-molded product M310 disposed therebetween, and the right drawing is a cross-sectional view perpendicular to the longitudinal direction of these members.

In the O-molding step, compressive strain as shown in fig. 4F is generated on the side of the contact portion M300C.

Here, the curvature of the centroid line of the curved portion may be 0.002mm^-1Above 0.02mm^-1The following ranges.

In such press forming, the forming condition ratio a is also 0.85 to 0.95 (see fig. 4). By setting the molding condition ratio a to a value within such a range, the portion to be abutted by the bent portion can be brought into close contact with high accuracy in the O-molding step, and the 3 rd mold M300 having the bent portion can be efficiently manufactured. The molding condition ratio setting step may be performed in 1 or more cycles to find a preferable range of the molding condition ratio a.

The 3 rd finding can also be applied to the bending forming process. An example in which the 3 rd finding of the present invention is applied to bending processing will be described below with reference to fig. 21A to 21D. Fig. 21A to 21D are diagrams for explaining an example in which the 3 rd finding of the present invention is applied to bending. In fig. 21D and 21F, arrows facing each other indicate compressive strain, and arrows facing opposite sides indicate tensile strain.

For example, as shown in fig. 21A, the 3 rd finding is an example of a part model (hereinafter, referred to as the 3 rd model) M300' having a curved portion in which a circular closed cross section is curved in a curved shape in a molding direction.

A rectangular metal material plate W300 'as shown in fig. 21B is formed in the order of the bending step and the O-forming step (abutting portion forming step), thereby forming a 3 rd mold M300'.

In the bending step, as shown in fig. 21C, a bent product M310 'is molded using a bending die (U-die) D310' including a bending die D311 'and a bending punch D312'. In addition, the left drawing of fig. 21C is a side view of the bending die D310 ' and the metal material plate W300 ' provided in the bending die D310 ', and the right drawing is a cross-sectional view perpendicular to the longitudinal direction of these members.

The bending die D311 ' is formed with a bending recess D311A ', and the bending recess D311A ' has a lower molded shape portion corresponding to the final shape of the 3 rd mold M300 ' within a range of approximately 180 ° from the shape center line (lower half) and an upper molded shape portion connected to the lower molded shape portion and formed by extending the upper end of the lower molded shape portion upward, when viewed from the shape center line direction of the 3 rd mold M300 '. The bending punch D312 ' is formed with a bending convex portion D312A ', and the bending convex portion D312A ' is configured to correspond to the inner peripheral surface of the bent product M310 ' with a predetermined interval from the bending concave portion D311A '.

Then, the metal material plate W300 'is bent by the bending punch D312' and the bending die D311 ', thereby forming a bent product M310' having a side opened by the bending punch D312 'and a side of the bending die D311' as a concave portion.

In the bending step, compressive strain as shown in fig. 21D is generated on the concave portion side of the bent product M310'.

In the O-molding step, as shown in fig. 21E, an O-molding step is performed using an O-mold D320'. Specifically, the 3 rd mold M300 ' is formed by the lower mold (1 st cavity) D321 ' having the lower mold recessed portion D321A ' formed therein and the upper mold (2 nd cavity) D322 ' having the upper mold recessed portion D322A ' formed therein along the side end portion M310E ' of the portion to be abutted, bringing the side end portions M310E ' of the portion to be abutted of the bent molded article M310 ' into abutment with each other to bring the side end portions M300C ' into abutment with each other. The left drawing of fig. 21E is a side view of the lower mold D321 ', the upper mold D322 ', and the bent molded article M310 ' disposed therebetween, and the right drawing is a cross-sectional view perpendicular to the longitudinal direction of these members.

In the O-molding step, tensile and compressive strains as shown in fig. 21F are generated on the side of the contact portion M300C'.

Here, the curvature of the centroid line of the curved portion may be 0.002mm^-1Above 0.02mm^-1The following ranges.

In such bending, the molding condition ratio a is also 0.85 to 0.95 (see 4 th finding). By setting the molding condition ratio a to a value within such a range, the portion to be abutted by the bent portion can be brought into close contact with high accuracy in the O-molding step, and the 3 rd mold M300' having the bent portion can be efficiently manufactured. The molding condition ratio setting step may be performed in 1 or more cycles to find a preferable range of the molding condition ratio a.

[ see 5 ] A

The metal material (metal plate) to which the above-described findings (and the embodiments described below) can be applied is not particularly limited, and may be, for example, a steel plate. Examples of the steel sheet include a thin material (thickness/equivalent diameter (diameter of a cross section perpendicular to the longitudinal direction of the cylindrical portion) of 10% or less), a high-strength material (tensile strength (TS) of 300MPa or more, and more preferably 400MPa or more), and the like. In the case of using these steel sheets, although the spring back is large, the spring back can be appropriately suppressed by setting the forming condition ratio a to 0.85 to 0.95. Examples of the other kinds of metal plates include Al plates. The thickness of the metal plate is not particularly limited, and may be, for example, 1.0 to 2.9 mm.

[ see 6 ]

For the evaluation of the amount of strain of the portion to be abutted, calculation based on a geometric relationship is effective, and for example, analysis using a finite element method is particularly effective.

As is clear from the above findings and the examples described later, for example, when a steel sheet UO having a tensile strength of 300 to 600MPa and a sheet thickness of 1.5 to 3.0mm is formed into a specific three-dimensional cylindrical portion, the specific three-dimensional cylindrical portion (member having the specific three-dimensional cylindrical portion) can be efficiently formed (manufactured) when all of the following conditions are satisfied.

A change Rh of 10-50% in the direction including the shape line and the contact part of the length of the cross-sectional shape changing part along the shape line, and a change Rc of the change rate of the circumference of the change rate changing part of the circumference of 0.035mm^-1～0.35mm^-1The curvature Rl of the curved portion is 0.002mm^-1～0.02mm^-1At least one of such conditions.

The molding condition ratio a is 0.85 to 0.95.

< embodiment 1 >

Hereinafter, a trailing arm main body according to embodiment 1 of the present invention will be described with reference to fig. 5 to 16G.

Fig. 5 is a perspective view illustrating a schematic configuration of a torsion beam assembly used in a torsion beam type rear suspension apparatus (torsion beam type suspension apparatus) according to embodiment 1 of the present invention.

In fig. 5, reference numeral 1 denotes a torsion beam assembly, reference numeral 10 denotes a trailing arm, and reference numeral 11 denotes a torsion beam. In the figure, symbol F indicates the front of the vehicle, and symbol R indicates the rear.

As shown in fig. 5, the torsion beam assembly 1 includes a pair of left and right trailing arms 10 that rotatably support left and right wheels, a torsion beam 11 that connects the left and right trailing arms 10, and a pair of left and right spring receiving portions 12 that support springs (not shown).

Further, one end side of a damper as a damper device is connected to a damper receiver, not shown, of the torsion beam assembly 1.

As shown in fig. 5, the trailing arm 10 includes, for example, a trailing arm body 100, a pivot mounting member 10F connected to a front end of the trailing arm body 100 and supported by the vehicle body via a pivot J, and a wheel mounting member 10R connected to a rear end and supporting a wheel.

The trailing arm body 100 according to embodiment 1 will be described below with reference to fig. 6 and 7A to 7D.

Fig. 6 is a perspective view illustrating the trailing arm body 100. Fig. 7A is a view of the trailing arm body 100 as viewed from the punch forming punch side in the forming direction of the trailing arm body 100, fig. 7B is a view of the trailing arm body 100 as viewed from a direction (i.e., a side surface) orthogonal to a plane including the centroid line and formed along the forming direction, fig. 7C is a view showing a front closed section 100F of the trailing arm body 100 as viewed from VIIC to VIIC in fig. 7B, and fig. 7D is a view showing a rear closed section 100R of the trailing arm body 100 as viewed from VIID to VIID in fig. 7B.

For example, as shown in fig. 6, 7A, and 7B, the trailing arm body 100 is an automobile component (part) provided with a tubular body (specific three-dimensional tubular portion) having a linear portion 101 of a rectangular closed cross section, a cross-sectional shape changing portion (specific three-dimensional shape portion) 102, a circumferential length changing portion 103, a curved portion (specific three-dimensional shape portion) 104 formed in the circumferential length changing portion 103, a circumferential length change rate changing portion (specific three-dimensional shape portion) 105, and a seam portion (joint portion) 100S joined by welding, which are formed in this order from the front closed cross section 100F toward the rear closed cross section 100R.

Further, for example, as shown in fig. 6 and 7C, the front closed section 100F of the trailing arm main body 100 is a rectangular closed section, and the pivot mounting member 10F is mounted to the front closed section 100F by welding.

As shown in fig. 6 and 7D, the rear closed cross section 100R is a circular closed cross section, and the wheel mounting member 10R side is mounted to the rear closed cross section 100R by welding.

In this embodiment, the joint portion 100S is disposed, for example, on the inner side of the vehicle body in the torsion beam assembly 1.

As shown in fig. 6 and 7A to 7B, the linear portion 101 has a rectangular closed cross section similar to the front closed cross section 100F and is formed linearly in a predetermined range from the front closed cross section 100F side toward the rear closed cross section 100R side.

The cross-sectional shape changing portion 102 is connected to the rear closed cross-section 100R side of the linear portion 101, and the rectangular closed cross-section of the linear portion 101 is formed so as to gradually transition to a circular closed cross-section along the centroid line toward the rear closed cross-section 100R side.

In this embodiment, the cross-sectional shape changing portion 102 has a length change in the direction including the centroid line of the cross-sectional shape and the abutting portion in a range of 10% to 50% (for example, 40%). Here, the two points set along the centroid line are, for example, the R-side end and the F-side end of the cross-sectional shape changing portion 102.

The circumferential length changing portion 103 is a portion which is formed of a circular closed cross section connected to the rear side of the cross-sectional shape changing portion 102, and the circumferential length of the circular closed cross section gradually increases (expands) as it goes to the front side along the centroid line.

In this embodiment, for example, a curved portion 104 is formed in the circumferential length changing portion 103, and a circumferential length change rate changing portion 105 is formed in the curved portion 104.

In this embodiment, the curved portion 104 is, for example, a portion formed from the middle of the circumferential length changing portion 103 to the rear closed cross section 100R, and the shape line is formed in a curved shape in side view.

In this embodiment, the curved portion 104 is formed such that the curvature of the centroid line (not shown) is 0.002mm ^-1Above 0.02mm^-1The following ranges.

In this embodiment, the circumference length change rate changing portion 105 is formed, for example, in the middle of the circumference length changing portion 103, and a concave portion and a convex portion are formed in the circumference length changing portion 103 as the circumference length change rate of the circular closed cross section that becomes longer at a predetermined rate toward the front side along the centroid line changes in the circumference length changing portion 103.

In this embodiment, the circumferential length change rate changing unit 105 is configured such that the change in the circumferential length change rate is 0.035mm^-1Above 0.35mm^-1Within the following ranges.

In this embodiment, for example, the circumferential length changing portion 103 is maintained in the expanded diameter state in the circumferential length changing portion 105, but the circumferential length changing portion 105 may be configured by a cylindrical portion that transitions into a linear shape in a diameter-reduced portion.

Next, an outline of a method for manufacturing the trailing arm main body 100 to which the method for forming the cylindrical portion of the present invention is applied will be described with reference to fig. 8. Fig. 8 is an example of a flowchart illustrating an outline of the method of manufacturing a component according to the present invention. In the present embodiment, the trailing arm body 100 is manufactured by press forming.

As shown in fig. 8, the manufacturing process of the trailing arm main body 100 includes, for example, a material steel plate (metal material plate) preparation process (S01), a press forming process (S02), a trimming process (non-flanging process) (S03), an O-forming process (abutting portion forming process) (S04), and a joining process (S05).

In embodiment 1, the dies used in the manufacturing process of the trailing arm body 100 include, for example, a press-forming die used in a press-forming process, a trimming die used in a trimming process (non-flanging process), and an O-forming die used in an O-forming process (abutment portion forming process).

[ preparation Process of Steel sheet Material (Metal Material plate) ]

(1) The material steel plate preparation step is a step of preparing a material steel plate (metal material plate) to be formed in the press forming step (S01).

In the material steel plate preparation step, for example, a material steel plate is prepared in which the flangeless press-formed product abutting in the abutting portion forming step is spread and a surplus material is added to the outer shape thereof. In addition, when the trimming step described later does not need to be set, the outer shape of the flangeless press-molded product after development may be maintained. For example, a rectangular steel plate material may be prepared on the premise that the shape is adjusted in the trimming step.

[ Press Molding Process ]

(2) The press-forming step is a step of press-forming a steel plate material (metal material plate) with a press-forming die to form a press-formed portion having a press-forming punch side opening in the Z-axis direction (S02).

In the press forming step, a steel plate material (metal material plate) is press-formed (press-formed) by a press forming die (press forming die), thereby forming a press-formed article (press-formed portion) having a cross-section view concave shape.

Finishing Process (non-Flanging Process)

(3) In embodiment 1, the trimming step (flangeless step) is a step of removing, with a trimming die, projecting portions (excess material formed by projecting both side end portions of a concave portion outward when viewed in cross section of a press-formed article) formed in the press-forming step to form a flangeless press-formed article having both side end portions (S03).

In the press forming step, when the flangeless press-formed product having no excess material can be formed, the flangeless step may be completed in a press-forming die.

[ O Molding Process ]

(4) The O-molding step (contact portion forming step) is a step of bringing the side end portion (the portion to be contacted) of the flangeless press-molded product into contact with the O-molding die (S04).

[ joining Process ]

(5) The joining step is a step of joining both side ends of the abutment portion-formed product (O-shaped product) to each other to form a joined portion (S05).

In the joining step, both side ends of the abutting portion of the finished abutting portion are joined to each other by welding or the like to form a joint portion (joint portion).

In the joining of the joint portion (joint portion), laser welding or the like can be applied in addition to arc welding.

Next, the manufacturing procedure of the trailing arm main body 100 according to embodiment 1 will be described in detail with reference to fig. 9, 10, 11A to 11C, 12A to 12C, 13A to 13C, 15A to 15G, and 16A to 16G.

Fig. 9 is a flowchart showing an example of a detailed sequence of manufacturing steps of the trailing arm main body 100, S101 shows a steel plate preparation step, S102 to S104 show a press forming step, SS105 to S107 show a trimming step (flangeless step), S108 to S111 show an O-forming step (abutting portion forming step), and S112 shows a joining step. S113 represents a step of attaching the pivot attachment member 10F and the wheel attachment member 10R to the trailing arm body 100 by welding to form the trailing arm 10.

Fig. 15A to 15G and fig. 16A to 16G are views showing details of a manufacturing process of the trailing arm body 100 according to embodiment 1. Fig. 15A to 15G show a process of forming the trailing arm body 100 as viewed from the front closed cross section 100F (see fig. 7B) side, and fig. 16A to 16G show views as viewed from the rear closed cross section 100R (see fig. 7B) side.

[ preparation of Steel sheet Material ]

First, the steel plate material preparation step (S101) shown in fig. 9 will be described.

In this embodiment, a steel plate (metal plate) is prepared as a material to which a surplus is added to a member after the flangeless press-molded product of the trailing arm body 100 is spread.

The steel sheet material W0 will be described below with reference to fig. 10. Fig. 10 is a diagram illustrating an example of a schematic configuration of a steel plate material used for manufacturing the trailing arm body 100 according to embodiment 1.

As shown in fig. 10, the steel plate W0 is formed by, for example, adding a surplus WH removed in a trimming step to a side end W10E of a developed view (a portion indicated by a two-dot chain line) of the flangeless press-molded product of the tow arm body 100.

The steel sheet W0 is formed from a front end WF corresponding to a rectangular closed cross section on the front side of the trailing arm body 100 toward a rear end WR corresponding to a circular closed cross section on the rear side, and includes a straight line corresponding portion W101 corresponding to the straight line portion 101, a cross-sectional shape change corresponding portion W102 corresponding to the cross-sectional shape change portion 102, a circumferential length change corresponding portion W103 corresponding to the circumferential length change portion 103, a bent corresponding portion W104 corresponding to the bent portion 104, and a circumferential length change rate change corresponding portion W105 corresponding to the circumferential length change rate change portion 105, and has a side portion WE including a surplus formed outside the side end portion W10E which is a portion to be abutted.

The steel sheet material W0 has the following outer shape: the linear corresponding portion W101 is formed in a rectangular shape, and the cross-sectional shape change corresponding portion W102 and the curved corresponding portion W103 are formed in a fan shape gradually widening from the front end portion WF toward the rear end portion WR and gradually widening in the vicinity of the circumferential length change rate changing portion 105.

In this embodiment, for example, a steel sheet having a tensile strength of 400MPa and a sheet thickness of 1.2mm is used.

Further, the material and thickness of the steel sheet material need not be limited, but the press forming method of embodiment 1 is preferably applied to a steel sheet (for example, a thin steel sheet) having a tensile strength of 300MPa or more, more preferably 400MPa or more and a thickness of about 1.0 to 2.9mm, and the influence of springback can be suppressed.

[ Press Molding Process ]

In the press forming step, as shown in S102 to S104 of fig. 9, the steel material plate is placed in a press forming die (press forming die), press-formed by a press forming punch, and the formed belt excess press-formed product is taken out.

The schematic configuration of the press mold D10 will be described below with reference to fig. 11A, 15B, 16A, and 16B. Fig. 11A is a perspective view illustrating a schematic configuration of a press mold according to embodiment 1.

In this embodiment, as shown in fig. 11A, 15B, 16A, and 16B, for example, the press-forming die D10 includes a press-forming lower die (press-forming die) D11 as a fixed die, a press-forming punch D12 disposed above the press-forming lower die D11 and movable in the vertical direction (Z-axis direction) relative to the press-forming lower die D11, and a steel plate pressing tool D13 for pressing the material steel plate W0 against the press-forming lower die D11 on both sides of the press-forming punch D12 during press-forming.

As shown in fig. 11A, the press-forming lower die D11 includes a press-forming recess D11A extending from a front-side shape portion D11F, which forms a portion corresponding to the front-side closed cross-section 110F (see fig. 15B) of the belt blank press-formed product 110, to a rear-side shape portion D11R, which forms a portion corresponding to the rear-side closed cross-section 110R (see fig. 16B).

The press-formed concave portion D11A is formed with a formed shape portion corresponding to the linear shape portion 101, the cross-sectional shape changing portion (specific three-dimensional shape portion) 102, the circumferential length changing portion 103, the bending portion (specific three-dimensional shape portion) 104, and the circumferential length change rate changing portion (specific three-dimensional shape portion) 105 of the rectangular closed cross section of the trailing arm main body 100 in the belt blank press-formed product 110.

The press forming punch (U forming punch) D12 is a die that cooperates with the press forming lower die D11 when the trailing arm main body 100 is manufactured, and performs press forming on the steel plate material W0 to form the strip surplus press-formed product 110.

As shown in fig. 11A, the press-forming punch D12 has press-formed protrusions D12A formed from a front-side forming protrusion D12F corresponding to the front-side closed cross-section 110F (see fig. 15B) of the belt blank press-formed product 110 to a rear-side forming protrusion D12R corresponding to the rear-side closed cross-section 110R (see fig. 16B) of the belt blank press-formed product 110. The width Du of the press punch D12 shown in fig. 11A indicates the width of a portion (distance between the inner circumferential surfaces of the portion) corresponding to the portion to be abutted when the flangeless press molded product 120 is formed by trimming the strip blank press molded product 110.

The press-formed convex portion D12A has a formed shape portion corresponding to the linear shape portion 101 of the rectangular closed cross section of the trailing arm main body 100, the cross-sectional shape changing portion (specific three-dimensional shape portion) 102, the circumferential length changing portion 103, the curved portion (specific three-dimensional shape portion) 104, and the circumferential length change rate changing portion (specific three-dimensional shape portion) 105 in the excess material press-formed product 110.

Further, on both sides of the press-forming concave portion D11A of the press-forming lower die D11, steel plate pressing shaped portions D11S corresponding to the press-forming concave portion D11A are formed, and the steel plate W0 that is placed in the steel plate pressing shaped portions D11S, for example, can be press-formed until the steel plate W0 is drawn into the press-forming concave portion D11A.

The steel plate pressing tool D13 is disposed above the press-forming lower die D11 across the press-forming recess D11A of the press-forming lower die D11, for example, and can be advanced and retracted vertically (in the Z-axis direction) with respect to the press-forming lower die D11.

The steel plate pressing tool D13 has a steel plate pressing portion D13S corresponding to the steel plate pressing portion D11S formed on the lower surface thereof, and presses the steel plate material W0 against the press-forming lower die D11 on both sides of the press-forming punch D12 during press-forming.

As shown in fig. 11B and 11C, the belt discard punch-formed product 110 formed in the punch-forming step of this embodiment includes a linear shape concave forming portion 111, a cross-sectional shape changing concave forming portion 112, a circumferential length changing concave forming portion 113, a curved concave forming portion 114, and a circumferential length change rate changing concave forming portion 115 corresponding to the linear shape portion 101, the cross-sectional shape changing portion 102, the circumferential length changing portion 103, the curved portion (specific three-dimensional shape portion) 104 formed in the circumferential length changing portion 103, and the circumferential length change rate changing portion 105 of the trailing arm main body 100, respectively.

Fig. 11B is a view of the belt blank press-formed product 110 as viewed from the lower side (the side opposite to the press-forming punch D12), and fig. 11C is a view of the press-formed product 110 as viewed from the direction (i.e., the side surface) orthogonal to the plane including the centroid line and formed in the forming direction.

The sequence of the press molding step will be described below.

(1) First, the steel plate material W0 is placed in the press-forming die D10 (S102).

When the steel sheet material W0 is placed in the press-forming die D10, as shown in fig. 15A and 16A, the steel sheet material W0 is placed in the press-forming die D11, the steel sheet pressing tool D13 is lowered, and the steel sheet material W0 is sandwiched between the steel sheet pressing shape portion D13S and the steel sheet pressing shape portion D11S.

Further, the press punch D12 is positioned above the steel material plate W0.

(2) The blank steel sheet W0 is pressed by the press-forming punch D12 (S103).

When the steel material plate W0 is pressed by the press punch D12, as shown in fig. 15B and 16B, the press punch D12 is lowered in the Z-axis direction, and the steel material plate W0 is held by the steel plate pressing member D13, and the steel material plate W0 is pressed by the press-forming protrusions D12A.

The steel sheet material W0 placed on the press-forming lower die D11 is sandwiched between the steel sheet pressing shape portion D11S and the steel sheet pressing shape portion D13S by the steel sheet pressing member D13 before being press-formed in the press-forming concave portion D11A, and the press-forming convex portion D12A and the press-forming concave portion D11A both draw-form the steel sheet material W0.

As a result, a belt excess press-formed article (press-formed article) 110 is formed. Further, since the steel sheet material W0 is pressed by the steel sheet pressing member D13, the steel sheet material W0 can be drawn stably.

In addition, when press forming is performed, there may be a portion which is not partially drawn.

In fig. 15A, 16A, 15B, and 16B, reference numerals D11F and D11R denote a front side shape portion and a rear side shape portion of the stamped concave portion D11A, and reference numerals D12F and D12R denote a front side shape portion and a rear side shape portion of the stamped convex portion D12A.

(3) The press-formed product with excess material (press-formed product) 110 is taken out from the press-forming lower die D11 (S104).

As shown in the right drawings of fig. 15B and 16B, the belt blank press-formed product (press-formed product) 110 has a concave portion, and one end side in the longitudinal direction is a front side cross section 110F corresponding to the front side closed cross section 100F (see fig. 7B) of the catcher arm 100, and the other end side is a rear side cross section 110R corresponding to the rear side closed cross section 100R (see fig. 7B).

Further, flange-like trims (protruding portions) 110H protruding outward from both side end portions of the concave portion when viewed in cross section of the strip-trim press-molded product 110 are formed.

Finishing Process (non-Flanging Process)

In embodiment 1, in the trimming step (flangeless step), as shown in S105 to S107 of fig. 9, the punched molded article 110 with the excess material is placed in a trimming mold, the excess material of the punched molded article is removed in the trimming mold to form a flangeless punched molded article, and the flangeless punched molded article is taken out from the trimming mold.

In this embodiment, an example is shown in which flange-like trims (protruding portions) 110H protruding outward from both end portions of the belt trim press-formed product (press-formed product) 110 shown in fig. 15B and 16B are formed at both end portions, and the trims 110H are removed in the trimming step. Whether or not the dressing step is provided can be arbitrarily set as necessary. For example, if the protruding portion is not present, the trimming process may be omitted.

The outline configuration of the trimming die D20 will be described below with reference to fig. 12A, 15C, and 16C. Fig. 12A is a perspective view illustrating a schematic configuration of a trimming die D20 according to embodiment 1.

For example, as shown in fig. 11A, 15C, and 16C, the truing die D20 includes a truing lower die D21, a pair of truing blades D22 disposed above the truing lower die D21, and a wedge mechanism D24 that is lowered to separate the truing blades D22 in the Y-axis direction. The trimming lower die D21 has a recess D21A, and the recess D21A is formed in a state where the belt blank press-formed product (press-formed product) 110 is disposed so that the blanks 110H, 110H can be removed from the front side shape portion 110F to the rear side shape portion 110R.

The dressing blade D22 and the wedge mechanism D24 are configured to be able to advance and retreat in the Z-axis direction with respect to the dressing lower die D21, and are configured to move the dressing blade D22 outward in the Y-axis direction by lowering the wedge mechanism D24 in a state where the dressing blade D22 is arranged at a predetermined position with respect to the blank press-molded article (press-molded article) 110, and to remove the blanks 110H, 110H in cooperation with the dressing lower die D21.

As shown in fig. 12B and 12C, the trimmed flangeless press-molded product 120 includes a linear concave molding portion 121, a shape change concave molding portion 122, a circumferential length change concave molding portion 123, a curved shape concave molding portion 124, and a circumferential length change rate change concave molding portion 125.

The linear concave molding portion 121, the shape change concave molding portion 122, the circumferential length change concave molding portion 123, the curved concave molding portion 124, and the circumferential length change rate change concave molding portion 125 are configured to remove the excess materials 110H, 110H from the linear concave molding portion 111, the cross-sectional shape change concave molding portion 112, the circumferential length change concave molding portion 113, the curved concave molding portion 114, and the circumferential length change rate change concave molding portion 115 of the strip excess material press-molded product 110, respectively.

Fig. 12B is a view of the trimmed flangeless press-formed product 120 as viewed from the lower side (the side opposite to the press-forming punch D12 in the press-forming step), and fig. 12C is a view of the flangeless press-formed product 120 as viewed from the direction (i.e., the side surface) orthogonal to the plane including the centroid line and formed along the forming direction.

The sequence of the trimming step (non-flanging step) will be described below.

(1) The belt excess material press-molded article (press-molded article) 110 is placed in the trimming die D20 (S105).

Specifically, as shown in fig. 15C and 16C, the belt blank press-formed product 110 is placed in the recessed portion D21A of the trimming lower die D21, the upper trimming blade D22 and the wedge mechanism D24 are lowered, and the left and right trimming blades D22 are positioned between the blanks 110H, 110H formed at both side end portions of the belt blank press-formed product 110.

Then, the wedge mechanism D24 is driven (the wedge mechanism D24 is further lowered), the left and right dresser blades D22 are moved to positions outside the trims 110H, 110H in the Y-axis direction, and the flange-shaped trims 110H, 110H are cut and removed.

(2) The flange-free press-molded product 120 having the side end portions (portions to be abutted) 120E and 120E formed thereon is formed by trimming the flange-like trims 110H and 110H on both sides by the trimming die D20 (S106).

(3) The formed flangeless press-molded product 120 is taken out from the trimming die D20 (S107).

As a result, as shown in fig. 15C and 16C, the excess materials 110H and 110H of the press-formed article 110 are removed, and the finished press-formed article (flangeless press-formed article) 120 in which the side end portions 120E and 120E are accurately formed is formed.

[ O Molding Process ]

In the O-forming step (abutment portion forming step), as shown in S108 to S111 of fig. 9, the flangeless press-formed product is placed in an O-forming die (abutment portion forming die), and the flangeless press-formed product is pressed in the O-forming die so that the portions to be abutted (side end portions) of the flangeless press-formed product abut against each other, and the abutting portion finished product is taken out.

The schematic configuration of the O-mold D30 will be described below with reference to fig. 13A, 15D to 15F, and 16D to 16F. Fig. 13A is a perspective view illustrating an O-mold D30 in manufacturing a trailing arm body according to embodiment 1.

For example, as shown in fig. 13A, 15D to 15F, and 16D to 16F, the O-mold D30 includes a lower mold (1 st cavity) D31 as a fixed mold, and an upper mold (2 nd cavity) D32 disposed above the lower mold D31 and capable of advancing and retreating in the Z-axis direction with respect to the lower mold D31.

Next, as shown in fig. 13A, in the lower die D31, a lower die recess D31A is formed from the front side shape portion 120F to the rear side shape portion 120R of the flangeless press-molded product 120, in which the flangeless press-molded product 120 is disposed.

Further, an upper die recess D32A is formed in the upper die D32, and the upper die recess D32A cooperates with the lower die recess D31A to extend along the side end portions 120E on both sides of the flangeless press-formed product 120, whereby the side end portions 120E are brought closer from the front side shape portion 120F to the rear side shape portion 120R, and further brought into contact with each other to form the contact portion forming product 130.

As shown in fig. 13B and 13C, the contact portion forming product 130 includes a linear portion 131, a cross-sectional shape changing portion 132, a circumferential length changing portion 133, a bent portion 134, and a circumferential length change rate changing portion 135.

The straight line portion 131, the cross-sectional shape changing portion 132, the circumferential length changing portion 133, the curved portion 134, and the circumferential length change rate changing portion 135 correspond to the straight line portion 101, the cross-sectional shape changing portion 102, the circumferential length changing portion 103, the curved portion 104, and the circumferential length change rate changing portion 105 of the trailing arm body 100, respectively.

Note that a symbol Do shown in fig. 13A indicates the width of the lower mold recess D31A of the lower mold (1 st concave mold) D31.

Fig. 13B is a view of the contact portion forming product 130 as viewed from the upper die D32 side, and fig. 13C is a view of the contact portion forming product 130 as viewed from a direction (i.e., a side surface) orthogonal to a plane including the centroid line formed along the molding direction.

Here, the molding conditions in manufacturing the trailing arm body 100 will be described with reference to fig. 14, as compared to a, the width Du of the press punch of the press die D10 shown in fig. 11A, and the width Do of the lower die recess D31A of the lower die (1 st concave die) D31 shown in fig. 13A. Fig. 14 is a diagram illustrating an outline of the molding condition ratio a (Du/Do) of the mold (the press-forming mold D10 and the abutment portion forming mold D30) according to embodiment 1.

As shown in fig. 14, the molding condition ratio a (Du/Do) at the time of manufacturing the trailing arm body 100 is configured to vary along the longitudinal direction (centroid line) of the trailing arm body 100.

Molding condition ratio a shown in fig. 14₁、a₂、a₃、a₄、a₅The configuration corresponds to the linear shape portion 101, the cross-sectional shape changing portion 102, the circumferential length changing portion 103, the curved portion 104, and the circumferential length change rate changing portion 105 of the trailing arm body 100, and changes along the shape line of the trailing arm body 100. Further, molding condition ratio a₁、a₂、a₃、a₄、a₅Is appropriately set to 0.85 to 0.95. The molding condition ratio setting step is performed in 1 or more cycles to set the values thereof.

In FIG. 14, the molding condition ratio is a₄Molding condition ratio a₅Although included in the molding condition ratio a₃However, in this case, the molding condition ratio a suitable for either one or both of them can be appropriately used.

Further, molding condition ratio a₁、a₂、a₃、a₄、a₅The molding condition ratio a shown in FIG. 14_iThe illustrated numerical expression defines that the width Du of the press-forming punch D12 corresponds to the symbol Du indicated for the press-forming punch D12 of the press-forming die D10 in fig. 11A. Further, the width Do of the lower mold recess (abutment forming recess) D31A of the abutment forming die D30 corresponds to the symbol Do shown in fig. 13A for the lower mold recess (abutment forming recess) D31A of the lower mold (1 st female mold) D31.

The width Du of the press punch D12 shown in fig. 11A and the width Do of the lower die recess D31A of the O-die D30 shown in fig. 13A correspond to positions in the longitudinal direction (X-axis direction) of the press punch D12 and the lower die recess (abutment portion forming recess) D31A that correspond to each other.

The width Du of the punch forming punch D12 and the width Do of the lower die recess D31A of the O-forming die D30 are values corresponding to the respective portions of the trailing arm body 100 shown in fig. 14. E.g. ratio to molding conditions a₂The width Du of the punch forming punch D12 and the width Do of the lower die recess D31A of the O-forming die D30 correspond to the width Du and the width Do of the portion where the cross-sectional shape changing portion 132 is formed. Therefore, even if the molding condition ratio a changes along the centroid line, the press-molding punch in the press-molding step and the 1 st die and the 2 nd die in the O-molding step do not need to be moved relative to each other in the direction orthogonal to the centroid line.

The process sequence in the contact portion forming process will be described below.

(1) The flangeless press-molded product 120 is placed in the O-mold D30 (S108).

When the flangeless press-formed product 120 is placed in the O-forming die D30, as shown in fig. 15D and 16D, the flangeless press-formed product 120 is placed in the lower die D31 in which the lower die recess D31A is formed, and the upper die D32 in which the upper die recess D32A is formed is positioned above.

(2) The flangeless press-molded product 120 is pressed by the O-mold D30 (S109).

When the flangeless press-formed product 120 is pressed by the O-forming die D30, as shown in fig. 15D and 16D, the flangeless press-formed product 120 is placed on the lower die D31, the upper die D32 is lowered, and the side end portions (portions to be abutted) 120E on both sides of the flangeless press-formed product 120 are deformed along the upper die concave portion D32A.

(3) The portions to be abutted of the flangeless press-formed product 120 are abutted (S110).

As shown in fig. 15E and 16E, the flangeless press-molded product 120 is pressed by the upper die recess D32A, whereby the flangeless press-molded product 120 is molded along the upper die recess D32A and the lower die recess D31A.

As a result, the side end portions 120E on both sides of the flangeless press-molded product 120 are abutted.

In fig. 15F and 16F, reference numerals D31F and D31R denote a front side shape portion and a rear side shape portion of the lower mold recess (abutment portion forming recess) D31A, and reference numerals D32F and D32R denote a front side shape portion and a rear side shape portion of the upper mold recess (abutment portion forming recess) D32A.

(4) The abutment portion forming product 130 is taken out of the O-mold D30 (S111).

As shown in the right drawings of fig. 15F and 16F, the abutting portion 130 is formed by abutting the side end portions 120E on both sides of the flangeless press-molded product 120 to form an abutting portion 130C.

Further, one end side of the contact portion forming product 130 is a front side cross section 130F corresponding to the front side closed cross section 100F of the trailing arm body 100, and the other end side is a rear side cross section 130R corresponding to the rear side closed cross section 100R.

[ joining Process ]

In this embodiment, in the joining step, both side ends 130E of the contact portion 130C of the contact portion finished product 130 are joined to each other by welding to form a joint portion (joint portion) 100S (S112).

When the abutting portion 130C of the abutting portion finished product 130 is joined by welding, as shown in fig. 15G and 16G, a seam portion 100S is formed. As a result, the trailing arm body 100 is formed.

In the joining of the joint portion (joint portion) 100S, laser welding or the like can be applied in addition to arc welding.

[ component mounting Process ]

In this embodiment, in the component mounting step, the pivot mounting component 10F and the wheel mounting component 10R are joined to the trailing arm main body 100 by welding (S113).

The pivot mounting member 10F and the wheel mounting member 10R are attached (welded) to the trailing arm main body 100.

As a result, the trailing arm 10 as shown in fig. 6 and 7A to 7D is formed.

According to the method of manufacturing the trailing arm body 100 (automotive component) of embodiment 1, the trailing arm body 100 including the cross-sectional shape changing portion 102, the curved portion 104, and the circumferential length change rate changing portion 105 can be efficiently manufactured.

According to the trailing arm body 100 and the method of manufacturing the trailing arm body 100 of embodiment 1, since the molding condition ratio a, which is made up of the ratio of the width Du of the press punch used when the press-molded portion is molded from the metal material sheet W0 in the press-molding step to the width Do of the recess of the O-mold D30 (more specifically, the width Do of the lower mold recess (abutment forming recess) D31A of the lower mold D31 and the upper mold recess (abutment forming recess) D32A of the upper mold D32), is set to 0.85 or more and 0.95 or less, the spring back can be appropriately suppressed, and the side end portions 120E on both sides can be brought into accurate and effective close contact with or close to the target positions.

Further, since the side end portions 120E on both sides of the abutting portion 130C are disposed close to each other after the O-molding step, the side end portions 120E can be joined efficiently without using a complicated jig or the like.

Further, since the molding condition ratio a (Du/Do) is set to be less than 1.0, the press-formed product 120 can be easily placed in the lower mold concave portion D31A and the upper mold concave portion D32A of the O-forming mold D30.

As a result, the trailing arm body 100 can be efficiently manufactured, and further, the parts and the automobile parts can be easily reduced in weight and the manufacturing cost can be reduced.

According to the method of manufacturing the trailing arm body 100 of embodiment 1, the curved portion 104 that curves in the plane along the molding direction is formed by the press-molding die D30, and therefore the trailing arm body 100 including the curved portion 104 can be efficiently formed.

According to the trailing arm body 100 and the method of manufacturing the trailing arm body 100 of embodiment 1, the molding condition ratio a is adjusted and set in accordance with the position of the trailing arm body 100 along the centroid line, and therefore the contact portion 130C of the contact portion forming product 130 can be brought into contact with (or brought close to) an engageable position with accuracy.

As a result, the trailing arm body 100 can be efficiently manufactured.

< embodiment 2 >

Hereinafter, embodiment 2 of the present invention will be described with reference to fig. 17A to 17C.

Fig. 17A to 17C are views for explaining an outline of a method of manufacturing the trailing arm main body according to embodiment 2 of the present invention, fig. 17A is a view showing a state in which a material steel plate is pressed by a steel plate pressing tool in a press-forming die, fig. 17B is a view showing a state in which a material steel plate is pressed against a press-forming die and press-formed in the press-forming die by cooperation of a press-forming punch and a counter punch, and fig. 17C is a view showing a state in which a flangeless press-formed product (press-formed product) is formed by completion of press-forming. In embodiment 2, each drawing is described with reference to the drawing viewed from the rear side of the trailing arm body.

In embodiment 2, the mold used in the manufacturing process of the trailing arm 10 includes, for example, a press-forming mold used in a press-forming process and an O-forming mold used in an O-forming process.

The difference between embodiment 2 and embodiment 1 is that, when press forming is performed in the press forming step, the flangeless step of forming the corresponding side end portion is completed in the press forming die using the steel sheet material without the excess material. Therefore, the punched product with the excess material can be taken out from the punching mold shown in S03 of fig. 8 and S105 to S107 of fig. 9 without removing the excess material by the trimming mold. The rest is the same as embodiment 1, and therefore, the description thereof is omitted.

The steel sheet material W0 according to embodiment 2 is configured such that, for example, the portion indicated by the two-dot chain line in fig. 9 shown in embodiment 1 corresponds to the outer shape. Further, if necessary, shape adjustment for completing the flangeless step by the press mold may be performed.

The press forming process and the flangeless process of embodiment 2 will be described below with reference to fig. 17A to 17C.

For example, as shown in fig. 17A to 17C, the press-forming die D10A includes a press-forming lower die (press-forming die) D11B as a fixed die, a press-forming punch D12 disposed above the press-forming lower die D11B and movable in the vertical direction (Z-axis direction) relative to the press-forming lower die D11B, a steel plate pressing tool D13 for pressing the material steel plate W0 against the press-forming lower die D11B on both sides of the press-forming punch D12 during press forming, and a counter punch D11C.

Like the press-forming lower die D11 shown in fig. 11A, the press-forming lower die D11B has a press-forming concave portion D11A extending from a front-side shape portion forming a portion corresponding to the front-side closed cross section in the flangeless press-formed product 120 to a rear-side shape portion D11R forming a portion corresponding to the rear-side closed cross section 120R in the flangeless press-formed product 120.

The press-formed concave portion D11A is formed with a formed shape portion corresponding to the linear shape portion 101 of the rectangular closed cross section of the trailing arm main body 100, the cross-sectional shape changing portion (specific three-dimensional shape portion) 102, the circumferential length changing portion 103, the curved portion (specific three-dimensional shape portion) 104 formed in the circumferential length changing portion 103, and the circumferential length change rate changing portion (specific three-dimensional shape portion) 105 in the flangeless press-formed product 120.

Further, in this embodiment, a hole D11H for accommodating the counter punch D11C is formed in the bottom of the press-forming recess D11A.

The counter punch D11C has, for example, a shape corresponding to the punch-forming recess D11A formed on the upper surface thereof, and is supported by a support rod D11L connected to the lower side.

The punch-molded recess D11A can be accommodated in the hole D11H formed in the bottom of the punch-molded recess D11A and can move forward and backward.

Further, the opposed punch D11C and the press punch D12 press the steel plate W0 sandwiched between them against the press concave D11A, and press-form them in cooperation with the press punch D12.

The press-forming punch D12, the press-forming protrusion D12A, and the steel plate pressing member D13 are the same as those in embodiment 1, and therefore, description thereof is omitted.

The sequence of the press molding step will be described below.

(1) First, as shown in fig. 17A, the steel plate W0 is placed in the press-forming die D11B.

When the steel plate W0 is placed in the press-forming die D11B, as shown in fig. 17A, the steel plate pressing tool D13 is lowered to hold the steel plate W0 by the steel plate pressing shape portion D13S and the steel plate pressing shape portion D11S.

Further, the press punch D12 is positioned above the steel material plate W0, and the counter punch D11C is raised to the vicinity of the steel material plate W0.

(2) Next, as shown in fig. 17B, the press punch D12 is lowered, the steel material plate W0 is sandwiched between the press punch D12 and the counter punch D11C, and the steel material plate W0 is pressed into the press concave D11A. As a result, the steel material plate W0 is formed into the flangeless press-formed product 120 along the press-formed recess D11A.

When the press-forming punch D12 is lowered to perform press-forming, both sides of the material steel plate W0 are pressed by the steel plate pressing tool D13.

(3) Next, as shown in fig. 17C, the press punch D12 is processed to the lowered end, and the counter punch D11C is housed in the hole D11H.

The material steel plate W0 is formed along the press-forming recessed portion D11A over the entire surface thereof, and both end portions WE10 of the material steel plate W0 are separated from the steel plate pressing tool D13 and pulled into the press-forming recessed portion D11A, thereby forming the side end portion 120E between the press-forming punch D12 and the press-forming recessed portion D11A. In addition, when press forming is performed, there may be a portion which is not partially drawn.

As a result, the side end portion is formed by the press mold D10A, and a trimming process (flangeless process) by a trimming mold is not required.

According to the method of manufacturing a member of embodiment 2, the flangeless press-formed product 120 having the side end portion 120E formed therein can be formed in the press-forming die D11A using the steel sheet material W0.

As a result, the flangeless press-formed product 120 can be efficiently formed without providing a flangeless step using a trimming die, and productivity can be improved.

According to the method of manufacturing a component of embodiment 2, since the press-forming punch D12 performs press-forming in cooperation with the counter punch D11C, when the both end portions WE10 are separated from the steel plate pressing tool D13 and pulled into the press-forming concave portion D11A, the portion corresponding to the side end portion 120E is stably press-formed, and therefore the side end portion can be stably formed.

As a result, the flangeless press-molded product 120 can be molded stably and with high quality.

< embodiment 3 >

Hereinafter, embodiment 3 will be described. Embodiment 3 is an example in which the trailing arm main body 100 described above is manufactured by bending. The configurations of the trailing arm main body 100, the trailing arm 10, and the torsion beam assembly 1 are the same as those of embodiment 1, and therefore, the description thereof is omitted.

First, an outline of a method of manufacturing the trailing arm main body 100 to which the method of manufacturing the member according to embodiment 3 is applied will be described with reference to fig. 22. Fig. 22 is an example of a flowchart illustrating an outline of the method for manufacturing a component according to embodiment 3.

As shown in fig. 22, the manufacturing process of the trailing arm main body 100 includes, for example, a steel plate (metal plate) preparation process (S01 '), a bending process (S02'), a contact portion forming process (S03 '), and a joining process (S04').

In this embodiment, the mold used in the manufacturing process of the trailing arm body 100 includes a bending mold used in the bending process and an O-molding mold (abutting portion forming mold) used in the O-molding process (abutting portion forming process).

[ preparation Process of Steel sheet Material (Metal Material plate) ]

(1) The material steel plate preparation step is a step (S01') of preparing a material steel plate (metal material plate) formed in the bending forming step.

In the material steel plate preparation step, for example, a material steel plate having an outer shape after the bent formed product (bent formed portion) is developed is prepared.

If necessary, a surplus material remaining outside the bending die after the bending step is completed may be formed in the outer shape of the bent product (bent portion). In this case, the excess material may also be removed by trimming after the bending.

[ bending Molding Process ]

(2) The bending step is a step of bending a steel plate material (metal material plate) by a bending die to form a bent portion having a bending punch side opening in the Z-axis direction (S02').

In the bending step, a steel plate (metal material plate) is bent by a bending die to form a bent product (bent portion).

[ O Molding Process ]

(3) The O-molding step (abutting portion forming step) is a step of abutting both end portions (portions to be abutted) of the bent molded article 120 '(see fig. 25B) with the O-molding die (abutting portion forming die) (S03').

In this embodiment, the step of abutting both side ends (portions to be abutted) of the bent molded article 120 'with the O-mold D30' is performed.

In the case where the bent product is formed from the steel sheet W0 'that does not correspond to the outer periphery of the bent product 120' in the bending step, the configuration may be such that the bent product is transferred to the contact portion forming step after the excess material formed on the outer periphery of the bent product is removed by trimming.

[ joining Process ]

(4) The joining step is a step of joining both side ends of the abutment portion-formed product (O-shaped product) to each other to form a joined portion (S04').

In the joining step, both side ends of the abutting portion of the finished abutting portion are joined to each other by welding or the like to form a joint portion (joint portion).

In the joining of the joint portion (joint portion), laser welding or the like can be applied in addition to arc welding.

Next, a manufacturing procedure of the trailing arm main body 100 according to embodiment 3 will be described in detail with reference to fig. 23, 24, 25A to 25C, 26A to 26C, 27, 28A to 28F, and 29A to 29F.

Fig. 23 is a flowchart showing an example of a detailed procedure of the manufacturing process of the trailing arm body 100, where S101 'shows a steel plate preparation process, S102' to S104 'show a bending forming process, S105' to S108 'show an O forming process (abutting portion forming process), and S109' shows a joining process. S110' represents a step of attaching the pivot attachment member 10F and the wheel attachment member 10R to the trailing arm body 100 by welding to form the trailing arm 10.

Fig. 28A to 28F and fig. 29A to 29F are views showing details of a manufacturing process of the trailing arm body 100 according to embodiment 3. Fig. 28A to 28F show a process of forming the trailing arm body 100 as viewed from the front closed cross section 100F (see fig. 7B), and fig. 15A to 15F show views as viewed from the rear closed cross section 100R (see fig. 7B).

[ preparation of Steel sheet Material ]

First, the steel plate material preparation step (S101') shown in fig. 23 will be described.

In this embodiment, a steel plate (metal plate) W0' formed in a shape obtained by spreading out the trailing arm body 100de is prepared.

The steel sheet material W0' will be described below with reference to fig. 24. Fig. 24 is a diagram illustrating an example of a schematic configuration of a steel plate material used for manufacturing the trailing arm body 100 according to embodiment 3.

As shown in fig. 24, the steel material plate W0 includes, for example, a straight line corresponding portion W101 'corresponding to the straight line shaped portion 101, a cross-sectional shape change corresponding portion W102' corresponding to the cross-sectional shape change portion 102, a circumferential length change corresponding portion W103 'corresponding to the circumferential length change portion 103, a curved portion W104' corresponding to the curved portion 104, and a circumferential length change rate change corresponding portion W105 'corresponding to the circumferential length change rate change portion 105 from a front side end WF' corresponding to a rectangular closed cross section on the front side of the trailing arm body 100 toward a rear side end WR 'corresponding to a circular closed cross section on the rear side, and the side ends WE' formed corresponding to the respective portions become portions to be abutted.

The steel sheet material W0' has the following outer shape: the linear corresponding portion W101 'is formed in a rectangular shape, and the cross-sectional shape change corresponding portion W102' and the curved corresponding portion W103 'are formed in a fan shape gradually widening from the front end WF' toward the rear end WR 'and gradually widening in the vicinity of the circumferential length change rate changing portion 105'.

In this embodiment, for example, a steel sheet of a material having a tensile strength of 400MPa and a sheet thickness of 1.2mm is used.

Further, the material and thickness of the steel sheet material need not be limited, but when the bending method of embodiment 3 is applied to a steel sheet material (for example, a thin steel sheet) having a tensile strength of 300MPa or more, more preferably 400MPa or more, and a thickness of about 1.0 to 2.9mm, it is preferable in that the influence of springback can be suppressed.

[ bending Molding Process ]

In the bending step, as shown in S102 'to S104' of fig. 23, the steel plate material is placed in a bending die, and is pressed by a bending punch to be bent, and the formed bent product (bent portion) is taken out.

The outline configuration of the bending die D10' will be described below with reference to fig. 25A, 28B, 29A, and 29B. Fig. 11A is a perspective view illustrating a bending mold in manufacturing the trailing arm body according to embodiment 3.

In this embodiment, for example, as shown in fig. 25A, 28B, 29A, and 29B, the bending die D10 ' includes a bending die D11 ' as a fixed die and a bending punch D12 ' disposed above the bending die D11 ' and capable of advancing and retreating in the vertical direction (Z-axis direction) with respect to the bending die D11 '.

As shown in fig. 25A, the bending die D11 ' has a bending recess D11A ' extending from a front-side shape portion D11F ' forming a portion corresponding to the front-side closed cross-section 120F ' in the bent product 120 ' shown in fig. 25B to a rear-side shape portion D11R ' forming a portion corresponding to the rear-side closed cross-section 120R '.

The curved molding recess D11A 'is formed with molded shape portions corresponding to the linear shape portion 101, the cross-sectional shape changing portion 102, the circumferential length changing portion 103, the curved portion 104, and the circumferential length change rate changing portion 105 of the rectangular closed cross-section of the trailing arm main body 100 in the curved molded article 120'.

The bending punch (U-forming punch) D12 'is a die for bending the steel material plate W0' in cooperation with the bending die D11 'to form the bent product 120' when the trailing arm body 100 is manufactured.

In the bending punch D12 ', a bending convex portion D12A' is formed from a front-side forming convex portion D12F 'corresponding to the front-side closed cross-section 120F' (see fig. 25B) of the bent product 120 'to a rear-side forming convex portion D11R' corresponding to the rear-side closed cross-section 120R '(see fig. 25B) of the bent product 120'.

The bent convex portion D12A 'has a molded shape portion corresponding to the linear shape portion 101, the cross-sectional shape changing portion 102, the circumferential length changing portion 103, the curved portion 104, and the circumferential length change rate changing portion 105 of the rectangular closed cross section of the trailing arm main body 100 in the bent molded article 120'.

Note that, a symbol Du shown in fig. 25A indicates the width of the bending convex portion D12A 'of the bending punch D12'.

As shown in fig. 25B and 25C, the bent molded article 120 'molded in the bending process of this embodiment includes a linear shape bent portion 121', a cross-sectional shape changing bent portion 122 ', a circumference length changing bent portion 123', a bent portion 124 ', and a circumference length change rate changing bent portion 125' corresponding to the linear shape portion 101, the cross-sectional shape changing portion 102, the circumference length changing portion 103, the bent portion (specific three-dimensional shape portion) 104 formed in the circumference length changing portion 103, and the circumference length change rate changing portion 105 of the trailing arm body 100.

Fig. 25B is a view of the bent product 120 ' as viewed from the upper side (the side of the bending punch D12 '), and fig. 25C is a view of the bent product 120 ' as viewed from a direction (i.e., a side surface) orthogonal to a plane formed along the molding direction and including the centroid line.

As shown in fig. 25B and 25C, the bent molded article 120 'includes a linear curved portion 121', a cross-sectional shape changing curved portion 122 ', a circumferential length changing curved portion 123', a curved shape curved portion 124 ', and a circumferential length change rate changing curved portion 125'.

The process sequence in the bending step will be described below.

(1) First, the steel material plate W0 ' is placed in the bending die D10 ' (S102 ').

When the steel material plate W0 'is placed in the bending die D10', as shown in fig. 28A and 29A, the steel material plate W0 'is placed in the bending die D11' with the bending convex portion D12A 'of the bending punch D12' positioned upward.

(2) The material steel plate W0 ' (S103 ') is pressed by the bending punch D12 '.

When the steel material plate W0 'is pressed by the bending punch D12', as shown in fig. 28B and 29B, the bending punch D12 'is lowered in the Z-axis direction, and the steel material plate W0' is pressed by the bending convex portion D12A ', and the bending punch D12' bends the steel material plate W0 'along the bending convex portion D12A' and the bending concave portion D11A 'in cooperation with the bending concave die D11'.

In fig. 28A, 29A, 28B, and 29B, reference numerals D11F 'and D11R' denote front and rear shape portions of the curve-formed concave portion D11A ', and reference numerals D12F' and D12R 'denote front and rear shape portions of the curve-formed convex portion D12A'.

(3) The bend-molded article 120 ' is taken out of the bend-molding die D11 ' (S104 ').

As shown in the right views of fig. 28B and 29B, the bent molded article 120 ' has a concave portion, and one end side thereof is a front side section 120F ' corresponding to the front side closed section 100F (see fig. 7B) of the trailing arm 100, and the other end side thereof is a rear side section 120R ' corresponding to the rear side closed section 100R (see fig. 7B).

[ O Molding Process ]

In the O-molding step (abutment portion forming step), as shown in S105 'to S108' of fig. 23, the bent molded article (bent molded portion) is placed in the O-molding die (abutment portion forming die), and the bent molded article (bent molded portion) is pressed in the O-molding die to bring the portions to be abutted of the bent molded article (bent molded portion) into abutment, thereby taking out the abutment portion finished product.

Next, a schematic configuration of the contact portion forming mold D30' will be described with reference to fig. 26A, 28C to 28F, and 29C to 29F. Fig. 26A is a perspective view illustrating an O-ring mold D30' in manufacturing the trailing arm body according to embodiment 3.

For example, as shown in fig. 26A, 28C to 28F, and 29C to 29F, the O-mold D30 ' includes a lower mold (1 st cavity) D31 ' as a fixed mold in which a contact portion forming recess is formed, and an upper mold (2 nd cavity) D32 ' disposed above the lower mold D31 ' and capable of advancing and retreating in the Z-axis direction relative to the lower mold D31 ' and in which a contact portion forming recess is formed.

As shown in fig. 26A, the lower die D31 ' has a lower die recess D31A ' extending from the front side shape portion 120F ' to the rear side shape portion 120R ' of the bent product 120 '.

In addition, an upper die recess D32A 'is formed in the upper die D32', and the upper die recess D32A 'cooperates with the lower die recess D31A' to extend along the side end portions 120E 'on both sides of the bent molded article 120', whereby the side end portions 120E 'are brought closer from the front side shape portion 120F' to the rear side shape portion 120R ', and are further brought into contact with each other to form the contact portion finished product 130'.

As shown in fig. 26B and 26C, the contact portion forming product 130 'includes a linear portion 131', a cross-sectional shape changing portion 132 ', a circumferential length changing portion 133', a bent portion 134 ', and a circumferential length change rate changing portion 135'.

The linear portion 131 ', the cross-sectional shape changing portion 132 ', the circumferential length changing portion 133 ', the curved portion 134 ', and the circumferential length change rate changing portion 135 ' correspond to the linear portion 101, the cross-sectional shape changing portion 102, the circumferential length changing portion 103, the curved portion 104, and the circumferential length change rate changing portion 105 of the trailing arm body 100, respectively.

Note that a symbol Do shown in fig. 26A indicates the width of the lower mold recess D31A 'of the lower mold (1 st concave mold) D31'.

Fig. 26B is a view of the contact portion forming product 130 'as viewed from the upper die D32 side, and fig. 26C is a view of the contact portion forming product 130' as viewed from a direction (i.e., a side surface) orthogonal to a plane including the centroid line formed along the molding direction.

Here, the molding conditions in manufacturing the trailing arm body 100 will be described with reference to fig. 27 as a ratio, a, the width Du of the bending punch of the bending die D10 ' shown in fig. 25A, and the width Do of the lower die recess D31A ' of the lower die (1 st concave die) D31 ' shown in fig. 26A. Fig. 27 is a diagram illustrating an outline of the molding condition ratio a (Du/Do) in the mold according to embodiment 3 (bending mold D10 'and O molding mold D30').

As shown in fig. 27, the molding condition ratio a (Du/Do) at the time of manufacturing the trailing arm body 100 is configured to vary along the longitudinal direction (centroid line) of the trailing arm body 100.

Molding condition ratio a shown in fig. 27₁、a₂、a₃、a₄、a₅Are respectively configured to be connected with the linear shape part 101 and the cross-sectional shape changing part 102 of the trailing arm main body 100The circumferential length changing portion 103, the curved portion 104, and the circumferential length change rate changing portion 105 change along the centroid line of the trailing arm main body 100 in a corresponding manner. Further, molding condition ratio a₁、a₂、a₃、a₄、a₅For example, it is suitably set to 0.85 to 0.95. The molding condition ratio setting step may be performed in 1 or more cycles to set the values thereof.

In FIG. 27, the molding condition ratio is a₄Molding condition ratio a₅Although included in the molding condition ratio a₃However, in this case, the molding condition ratio a suitable for either one or both of them can be appropriately used.

Further, molding condition ratio a₁、a₂、a₃、a₄、a₅The molding condition ratio a shown in FIG. 27_iThe width Du of the bending punch D12 'corresponds to the symbol Du indicated by the bending punch of the bending die D10' in fig. 25A, and the width Do of the lower die recess D31A 'of the O-forming die D30' corresponds to the symbol Do indicated by the lower die recess (abutment forming recess) D31A 'of the lower die (1 st die) D31' in fig. 26A.

The width Du of the bending punch D12 ' shown in fig. 25A and the width Do of the lower mold recess D31A ' of the O-mold D30 ' shown in fig. 26A correspond to each other at positions corresponding to each other in the longitudinal direction (X-axis direction) of the bending punch D12 ' and the lower mold recess D31A '.

The width Du of the bending punch D12 ' and the width Do of the lower die recess D31A ' of the O-die D30 ' are values corresponding to the respective portions of the trailing arm body 100 shown in fig. 27. E.g. ratio to molding conditions a ₂The width Du of the punch D12 'and the width Do of the lower die recess D31A' of the O-die D30 'correspond to the width Du and the width Do of the portion where the cross-sectional shape changing portion 132' is molded. Therefore, even if the molding condition ratio a varies along the shape axis, the bending punch in the bending step, and the 1 st die and the 2 nd die in the O-molding step do not need to be orthogonal to the shape axisAre relatively moved in the direction of (a).

The process sequence in the contact portion forming process will be described below.

(1) The bent molded product 120 ' is disposed in the O-mold D30 ' (S105 ').

When the bent molded article 120 ' is placed in the O-mold D30 ', as shown in fig. 28C and 29C, the bent molded article 120 ' is placed in the lower mold D31 ' in which the lower mold concave portion D31A ' is formed, and the upper mold D32 ' in which the upper mold concave portion D32A ' is formed is positioned upward.

(2) The bent molded product 120 ' is pressed by the O-mold D30 ' (S106 ').

When the bent molded article 120 'is pressed by the O-mold D30', as shown in fig. 28C and 29C, the bent molded article 120 'is placed on the lower mold D31', the upper mold D32 'is lowered, and the side end portions (portions to be abutted) 120E' on both sides of the bent molded article 120 'are deformed along the upper concave portion D32A'.

(3) The portions to be abutted of the bent molded article 120' are abutted (S107).

As shown in fig. 28D and 29D, the bent product 120 ' is molded along the upper concave portion D32A ' and the lower concave portion D31A ' by pressing the bent product 120 ' with the upper concave portion D32A '.

As a result, the side end portions 120E 'on both sides of the bent molded article 120' are brought into contact with each other.

In fig. 28E and 29E, reference numerals D31F 'and D31R' denote front and rear shape portions of the lower mold recess (contact portion forming recess) D31A ', and reference numerals D32F' and D32R 'denote front and rear shape portions of the upper mold recess (contact portion forming recess) D32A'.

(4) The abutment portion forming product 130 ' is taken out of the O-molding die D30 ' (S108 ').

As shown in the right views of fig. 28E and 29E, the abutting portion 130 'is formed by abutting the side end portions 120E' on both sides of the bent molded article 120 'to form abutting portions 130C'.

Further, one end side of the abutting portion forming product 130 ' is a front side cross section 130F ' corresponding to the front side closed cross section 100F of the trailing arm body 100, and the other end side is a rear side cross section 130R ' corresponding to the rear side closed cross section 100R.

[ joining Process ]

In this embodiment, in the joining step, both side end portions 130E ' of the contact portion 130C ' of the contact portion finished product 130 ' are joined to each other by welding to form a joint portion (joint portion) 100S ' (S109 ').

When the abutting portion 130C ' of the abutting portion finished product 130 ' is joined by welding, as shown in fig. 28F and 29F, a seam portion 100S ' is formed. As a result, the trailing arm body 100 is formed.

In the joining of the joint portion (joint portion) 100S', laser welding or the like can be applied in addition to arc welding.

[ component mounting Process ]

In this embodiment, in the component mounting step, the pivot mounting component 10F and the wheel mounting component 10R are joined to the trailing arm main body 100 by welding (S110').

The pivot mounting member 10F and the wheel mounting member 10R are mounted to the trailing arm main body 100 by joining (welding).

As a result, the trailing arm 10 as shown in fig. 6 and 7A to 7D is formed.

According to the method of manufacturing the trailing arm body 100 (automotive component) of embodiment 3, the trailing arm body 100 including the cross-sectional shape changing portion 102 and the circumferential length change rate changing portion 105 can be efficiently manufactured.

According to the method of manufacturing the trailing arm body 100 of embodiment 3, the molding condition ratio a, which is a ratio of the width Du of the bending punch used when the bent portion is molded from the metal material sheet W0 'in the bending step to the width Do of the O-mold (more specifically, the width Do of the lower mold concave portion (abutment forming concave portion) D31A' of the lower mold D31 'and the upper mold concave portion (abutment forming concave portion) D32A' of the upper mold D32 '), is set to 0.85 or more and 0.95 or less, so that springback can be appropriately suppressed, and the side end portions 120E' on both sides can be brought into close contact with each other accurately and effectively or close to the target positions.

Further, after the abutting portion forming step, the side end portions 120E 'on both sides, which become the abutting portion 130C', are disposed close to each other, whereby the joining can be performed efficiently without using a complicated jig or the like.

Further, since the molding condition ratio a is set to be less than 1.0, the press-formed product 120 can be easily disposed in the lower die recess D31A ' and the upper die recess D32A ' of the O-forming die D30 '.

As a result, the trailing arm body 100 can be efficiently manufactured, and further, the parts and the automobile parts can be easily reduced in weight and the manufacturing cost can be reduced.

Further, according to the method of manufacturing the trailing arm body 100 of embodiment 3, the curved portion 104 that is curved in the plane along the molding direction is formed by the press-molding die D30', and therefore the trailing arm body 100 including the curved portion 104 can be efficiently formed.

According to the trailing arm body 100 and the method of manufacturing the trailing arm body 100 of embodiment 3, the molding condition ratio a is adjusted and set in accordance with the position of the trailing arm body 100 along the centroid line, and therefore the abutting portion 130C 'of the abutting portion forming product 130' can be brought into accurate abutment (or brought close to the engageable position).

As a result, the trailing arm body 100 can be efficiently manufactured.

The present invention is not limited to the above embodiments, and various modifications can be made without departing from the scope of the invention.

For example, in the above-described embodiment, the description has been given of the case where the member is the trailing arm body 100 (trailing arm 10), but the present invention may be applied to other automobile members instead of the trailing arm body 100.

In addition, the present invention can be applied to members constituting building structures and machine structures instead of automobile members.

For example, the method of manufacturing a member of the present invention may be applied to manufacture of a line pipe or the like in which a circumferential rate-of-change portion, a cross-sectional shape-changing portion, and a curved portion are formed in a part or over the entire length.

In the above embodiment, the molding condition ratio a is set to be 0.85 to 0.95 over the entire length of the contact portion forming product 130 forming the trailing arm body 100, and the molding condition ratio a at each portion changes along the centroid line, but for example, the molding condition ratio a may be set to be 0.85 to 0.95 for the entire length or a part of the specific three-dimensional cylindrical portion, and the molding condition ratio a may be set to be other than the range of 0.85 to 0.95 at the other portions, or the molding condition ratio a may be set to a constant value over the entire length.

The molding condition ratio a may be set to 0.85 to 0.95 for the cylindrical portions other than the cross-sectional shape changing portion, the curved portion, and the circumferential length change rate changing portion.

In the above embodiment, the case where the molding condition ratio a is determined by the finite element method has been described, but the molding condition ratio a may be set by a calculation method or an experiment other than the finite element method, for example.

In the above-described embodiment, the description has been given of the case where the drag arm main body (automobile component, member) 100) is formed as the cylindrical portion over the entire length, but the present invention can be applied to, for example, a component having a blade-like configuration (for example, a mounting rib or a stay) or a pipe-like configuration (for example, a connection arm portion) other than the cylindrical portion formed in a part of the component.

Further, in the above-described embodiment, the case where the side end portions 120E and 120E ' on both sides of the press-molded article 120 and the bent molded article 120 ' are joined after being brought into close contact with each other substantially over the entire length thereof has been described, but for example, the side end portions 120E and 120E ' on both sides may be brought into contact with each other (disposed to face each other) with a gap to such an extent that they can be joined by welding or the like, a gap may be formed in a part of the side end portions after being brought into close contact with each other, and the side end portions on both sides may be disposed in proximity to each other with a predetermined gap over the entire length thereof.

Further, in the case where the gap is formed, the interval of the gap may be formed to be different depending on the position along the gap.

Whether or not the abutting portions are joined by welding or the like can be arbitrarily set, and a configuration in which a part of the abutting portions are joined may be adopted.

In the above-described embodiment, the description has been given of the case where the trailing arm body (automobile component) 100 having the circular closed cross section and the rectangular closed cross section is applied, but it is needless to say that the present invention may be applied to a component having a polygonal closed cross section (including a regular polygon and a polygon other than a regular polygon) instead of the circular closed cross section and the rectangular closed cross section.

In the above embodiment, the drag arm body 100 includes the cross-sectional shape changing portion 102 having a cross-sectional shape whose length in a direction including the centroid line and the contact portion changes by 10% to 50%, and a curvature of 0.002mm^-1Above 0.02mm^-1The change in the circumferential length change rate of the following curved portion 104, 1 st end portion (starting point) and 2 nd end portion (end point) was 0.035mm^-1Above 0.35mm^-1The following description is given of the case of the circumferential length change rate changing portion 105, but it is sufficient to provide at least one of the cross-sectional shape changing portion 102, the curved portion 104, and the circumferential length change rate changing portion 105. The values of the cross-sectional shape changing portion 102, the curved portion 104, and the circumferential length change rate changing portion 105 are not limited to the above ranges, and can be set as appropriate.

In the above embodiment, the case where the flat steel plate materials W0, W0 ' are press-formed or bent has been described, but, for example, a configuration may be adopted in which a step of applying curvature to the side end portions WE, WE ' on both sides in the width direction of the steel plate materials W0, W0 ' along the edge portions is accompanied before the press-forming or bending shown in fig. 15A, 16A, 28A, and 29A is performed. The press forming step (or bending step) and the O-forming step may be accompanied by a step of punching, providing local unevenness, or shaping. In the contact portion forming step, a core may be inserted into a part or the whole of the cylindrical portion to perform molding.

In the above embodiment, the case where the molding condition ratio a optimized by evaluating the molding condition ratio a, the material characteristics of the member, the shape and the plate thickness of the metal material plate, the molding condition in the bending molding step, and the molding condition in the abutment portion forming step based on the setting is applied has been described, but other parameters may be used instead of the above, and the molding condition ratio a may be evaluated including the other parameters.

In addition, in the above-described embodiment 1, the case where the press-formed article 120 after trimming the press-formed article (press-formed article) 110 having the flange-like discard is brought into contact with each other in the contact portion forming step has been described, but whether or not the trimming step is provided may be arbitrarily set, and a discard (protruding portion) protruding along a wall portion which becomes a concave shape in cross section may be formed.

In the above embodiment, the case where the trailing arm body 100 is integrally formed in the press-forming step (or bending step) and the O-forming step has been described, but for example, a closed cross section such as a circular closed cross section or a polygonal closed cross section may be formed in the press-forming step (or bending step) and the abutting portion forming step, and the trailing arm body 100 may be formed by shaping the closed cross section.

In the above embodiment, the case where the metal material plate is, for example, a steel plate having a tensile strength of 400MPa was described, but it is needless to say that the metal material plate may be applied to a steel plate having a tensile strength of less than 400MPa or a metal material plate other than a steel plate having a tensile strength of less than 400MPa and a steel plate having springback, in addition to a steel plate having a tensile strength of more than 400MPa, which is likely to cause springback.

Examples

Next, examples of the present embodiment will be explained. In the present example, the following experiment was performed to confirm the effects of the above embodiments.

<1. Experimental example 1>

In experimental example 1, the 2 nd mold M200 (see 2 nd) was manufactured by press forming. As the metal material plate W200, a steel plate having a tensile strength of 600MPa and a thickness of 2.0mm was used. Then, the molding condition ratio a and the length of the cross-sectional shape changing portion M203 in the direction including the centroid line and the contact portion M200C were variously changed along the change Rh of the centroid line to manufacture the 2 nd model M200, and the quality of these 2 nd models M200 was evaluated. Rh is the median of the values measured at both ends and the central portion in the longitudinal direction of the cross-sectional shape changing portion M203. Further, the outer diameter of the circular closed cross section M202 is 40mm in total. The evaluation items were "gap between abutting portions after springback" and "shape accuracy after springback". Details of the evaluation method are as follows.

(gap between abutting portions after springback)

After the 2 nd mold M200 was taken out of the O-mold D220 (i.e., after the 2 nd mold M200 rebounded), the distance between the abutting portions M200C was measured. Then, the gap between the abutting portions after springback was evaluated according to the following evaluation criteria. A to C were rated as acceptable. The results are summarized in Table 1.

A: contact between abutting parts

B: the distance between the abutting parts is less than or equal to 0.5mm

C: the distance between the abutting parts is less than 2.0mm

D: the distance between the abutting parts is more than 2.0mm

(accuracy of shape after springback)

After the 2 nd model M200 was taken out of the O-mold D220 (i.e., after the 2 nd model M200 rebounded), the height of the 2 nd model M200 (the distance from the outer peripheral surface portion of the abutment portion to the outer peripheral surface portion opposing the abutment portion (i.e., the outer diameter)) was measured. Further, in a state where the upper mold D222 and the lower mold D221 were completely butted against each other, a distance (height of the molding surface of the O-mold D220) from the upper end of the upper mold concave portion D222A to the lower end of the lower mold concave portion D221A was measured. Then, the height of the 2 nd model M200 was divided by the height of the molding surface of the O-mold D220, and the shape accuracy after springback was evaluated based on the obtained evaluation value and the following evaluation criteria. A to c are set as the pass rating. The results are summarized in Table 1.

a: an evaluation value of 1.00 or more and less than 1.01

b: an evaluation value of 1.01 or more and less than 1.03

c: an evaluation value of 1.03 or more and less than 1.05

d: an evaluation value of 1.05 or more

[ Table 1]

<2. Experimental example 2>

In experimental example 2, the 1 st model M100' (1 st finding) was produced by bending. As the metal material plate W100', a steel plate having a tensile strength of 600MPa and a thickness of 1.6mm was used. The molding condition ratio a and the circumferential length change rate Rc of the circumferential length change rate changing portion M103 'were variously changed to evaluate the quality of the 1 st model M100'. The circumferential length change rate Rc is a value obtained by dividing the difference in circumferential length change rate measured at both ends of the circumferential length change rate change portion M103' by the interval (length, size) between the both ends along the centroid line. The evaluation items were "gap between abutting portions after springback" and "shape accuracy after springback". The evaluation items were measured and evaluated in the same manner as in example 1. The results are summarized in Table 2.

[ Table 2]

<3. Experimental example 3>

In experimental example 3, the 3 rd model M300' was manufactured by bending (see 3 rd). As the metallic material plate W300', a steel plate having a tensile strength of 600MPa and a thickness of 2.8mm was used. The molding condition ratio a and the curvature Rl of the 3 rd model M300 'were variously changed to evaluate the quality of the 3 rd model M300'. The curvature Rl is a median value of values measured at both end portions and the center portion of the 3 rd model M300'. The evaluation items were "gap between abutting portions after springback" and "shape accuracy after springback". The evaluation items were measured and evaluated in the same manner as in example 1. The results are summarized in Table 3.

[ Table 3]

As is clear from tables 1 to 3, good results were obtained when the molding condition ratio a was 0.85 to 0.95. In addition to these conditions, 10 to 50% of Rh and 0.035mm of Rc are added^-1～0.35mm^-1Rl is 0.002mm^-1～0.02mm^-1In the case of (2), more favorable results can be obtained. Therefore, it is understood that the preferable results can be obtained from the above findings and embodiments.

In addition, although the steel sheet was tested in the above examples, the same results as in examples 1 to 3 were obtained when the same tests as in examples 1 to 3 were carried out for the Al sheet.

Industrial applicability

According to the method for manufacturing a part, the method for manufacturing an automobile part, and the mold of the present invention, since a part typified by an automobile part having a specific three-dimensional cylindrical portion can be efficiently manufactured, the method can be industrially used.

Description of symbols:

w0: a material steel plate (metal material plate); 10: trailing arms (parts, automobile parts); d10, D10A: punching and forming a die; d11: punching and forming a female die; D11A: punching and forming a concave part; D11B: punching and forming a concave part; D11C: an opposing punch; d12: punching and forming a punch; D12A: punching and forming a convex part; d13: a steel plate pressing member (metal material pressing member); d30: o, forming a mold; d31: a lower die (1 st concave die); D31A: a lower die recess (1 st recess); d32: an upper die (2 nd die); D32A: an upper die recess (2 nd recess); 100: a trailing arm body (cylindrical portion, member, automobile member); 101: a linear portion; 102: a cross-sectional shape changing portion; 103: a perimeter changing section; 104: a bending section; 105: a circumferential length change rate changing section; 110: press-formed products (press-formed products) with excess materials; 110F: front side cross-section (with excess material punch forming); 110R: rear cross-section (with excess punch forming); 120: a flangeless press-formed article (a finished press-formed article); 120F: front side cross-section (side flangeless punch molded article); 120R: rear side cross-section (non-flanged press-formed article); 130: forming a finished product by the abutting part; 130C: an abutting portion; 130F: front side cross section (abutment formation finished product); 130R: rear side cross section (abutment portion finished product).