阅读说明：本技术 坯料以及构件 (Blank and component ) 是由 园部苍马 伊藤泰弘 于 2020-04-09 设计创作，主要内容包括：本发明涉及坯料以及构件,上述坯料的特征在于,由钢材构成,具有至少两个凸部区域(313),该凸部区域的外缘(311)在面内方向上朝外侧成为凸状,在凸部区域(313)中至少局部地形成有软化部(320),且在凸部区域(313)的外缘的至少一部分形成有软化部(320),软化部(320)的维氏硬度被设定得低于主部区域(310)的维氏硬度,至少具有两个形成有软化部(320)的凸部区域(313)。(The present invention relates to a blank and a member, the blank is made of a steel material, and has at least two convex regions (313), the outer edge (311) of the convex region is convex towards the outside in the in-plane direction, a softening part (320) is at least partially formed in the convex region (313), the softening part (320) is formed at least on a part of the outer edge of the convex region (313), the Vickers hardness of the softening part (320) is set to be lower than the Vickers hardness of a main region (310), and the blank has at least two convex regions (313) formed with the softening part (320).)

1. A blank, characterized in that,

is made of steel materials, and is characterized in that,

has at least two convex regions, the outer edge of the convex region is convex towards the outer side in the in-plane direction,

a softened portion is formed at least partially in the convex portion region, and the softened portion is formed at least in a part of an outer edge of the convex portion region,

the Vickers hardness of the above-mentioned softened portion is set lower than that of the main portion region,

the liquid crystal display device has at least two convex regions in which the softening portions are formed.

2. The blank according to claim 1,

the convex region where the softened portion is formed is,

the radius of curvature R of the outer edge of the convex region is 150mm or less,

the opening angle of the outer edge is 120 DEG or less.

3. A blank according to claim 1 or 2,

the main portion region of the blank has a tensile strength of 1100MPa or more.

4. A blank according to any one of claims 1 to 3,

the tensile strength of the softened portion is 1000MPa or less.

5. A blank according to any one of claims 1 to 4,

the ratio of the Vickers hardness of the softened portion to the Vickers hardness of the main portion region of the blank is 0.4 to 0.9.

6. A structural member characterized in that it comprises, in a first aspect,

is made of steel materials, and is characterized in that,

comprising:

a bottom surface portion;

a 1 st vertical wall portion and a 2 nd vertical wall portion provided upright from an end of the bottom surface portion; and

at least two corner portions provided between the 1 st vertical wall portion and the 2 nd vertical wall portion,

a softening part is at least partially formed at the corner part,

the Vickers hardness of the softened portion is set lower than the Vickers hardness of the main portion region of the member,

the corner portion has at least two of the softening portions.

7. The component of claim 6,

the main portion region of the member has a tensile strength of 1100MPa or more.

8. Component according to claim 6 or 7,

the tensile strength of the softened portion is 1000MPa or less.

9. The member according to any one of claims 6 to 8,

the ratio of the Vickers hardness of the softened portion to the Vickers hardness of the main portion region of the member is 0.4 to 0.9.

10. Component according to one of claims 6 to 9,

the corner portion includes a constricted flange portion.

Technical Field

The present invention relates to a blank and a member.

The present application is based on application No. 2019-074618 filed in japan on 4/10 in 2019 and claims priority, and the contents thereof are incorporated herein.

Background

When a blank is machined to form a molded article having a predetermined shape, the blank may be subjected to various treatments in advance to adjust the properties and functions of the blank.

Patent document 1 describes the following technique: in the composite material, when the weld line is disposed in the region that becomes the concave shape of the extended flange portion after molding, the ductility of the extended flange portion is ensured by softening it by locally performing laser irradiation.

Patent document 2 describes the following technique: in the blank, the area of the ridge line portion in the member having the cross-sectional hat shape after molding is locally softened.

Documents of the prior art

Patent document

Patent document 1: japanese laid-open patent publication No. H06-226479

Patent document 2: japanese patent laid-open publication No. 2011-

Disclosure of Invention

Problems to be solved by the invention

However, in either of the above documents, the problem of the constricted flange portion formed by compression deformation is not considered. The technique described in patent document 1 is for securing ductility of an elongated flange portion formed by tensile deformation by local softening, and does not consider the problem of a contracted flange portion formed by compression deformation.

The technique described in patent document 2 is also intended to improve the flexibility of the ridge line portion of the cross-sectional hat shape after molding by local softening, and does not consider the problem of shrinkage of the flange portion. In particular, in the techniques described in patent documents 1 and 2, the influence of wrinkles generated in the constricted flange portion is not considered.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a new and improved blank capable of suppressing an influence due to wrinkles generated in a shrunk flange portion or the like.

Means for solving the problems

(1) According to an aspect of the present invention, there is provided a blank made of a steel material, comprising at least two convex regions, an outer edge of each of the convex regions being convex outward in an in-plane direction, wherein a softened portion is formed at least partially in each of the convex regions, the softened portion is formed at least partially in at least a part of the outer edge of each of the convex regions, and wherein the softened portion has a lower vickers hardness than a main portion region, and wherein the blank comprises at least two convex regions each of which has the softened portion formed therein.

(2) In the blank according to the above (1), in the convex region in which the softened portion is formed, a radius of curvature R of an outer edge of the convex region may be 150mm or less, and an opening angle of the outer edge may be 120 ° or less.

(3) In the blank according to the above (1) or (2), the tensile strength of the main portion region of the blank may be 1100MPa or more.

(4) In the blank according to any one of the above (1) to (3), the softened portion may have a tensile strength of 1000MPa or less.

(5) In the blank according to any one of the above (1) to (4), a ratio of a vickers hardness of the softened portion to a vickers hardness of the main portion region of the blank may be 0.4 or more and 0.9 or less.

(6) Another aspect of the present invention provides a member made of a steel material, comprising: a bottom surface portion; a 1 st vertical wall portion and a 2 nd vertical wall portion provided upright from an end portion of the bottom surface portion; and at least two corner portions provided between the 1 st vertical wall portion and the 2 nd vertical wall portion, wherein a softened portion is formed at least partially in the corner portions, the softened portion has a Vickers hardness set lower than that of a main portion region of the member, and the corner portions have at least two of the corner portions formed with the softened portions.

(7) In the member according to the above (6), the tensile strength of the main portion region of the member may be 1100MPa or more.

(8) In the member according to the above (6) or (7), the tensile strength of the softened portion may be 1000MPa or less.

(9) In the member according to any one of (6) to (8), a ratio of a vickers hardness of the softened portion to a vickers hardness of the main portion region of the member may be 0.4 or more and 0.9 or less.

(10) In the member according to any one of (6) to (9), the corner portion may include a constricted flange portion.

ADVANTAGEOUS EFFECTS OF INVENTION

According to the present invention, a new and improved blank is provided, which can suppress the influence of wrinkles generated in the shrunk flange portion and the like.

Drawings

Fig. 1A is a perspective view showing an example of a blank according to embodiment 1 of the present invention.

Fig. 1B is a perspective view showing an example of a molded article according to this embodiment.

Fig. 2A is a plan view showing an example of a blank according to embodiment 2 of the present invention.

Fig. 2B is a perspective view showing an example of the seat cushion frame according to the embodiment.

Fig. 3 is a sectional view showing a convex portion region according to embodiment 2 of the present invention.

Fig. 4 is a view showing an automobile frame as an example of a frame member formed by applying the blank according to any one of the embodiments of the present invention.

Fig. 5A is a diagram showing an example of a member molded using the blank according to any one of the embodiments of the present invention.

Fig. 5B is a diagram showing an example in which a member molded using the blank according to any one of the embodiments of the present invention is applied.

Fig. 6A is a diagram showing a model of a material used for simulation analysis as a comparative example.

Fig. 6B is a diagram showing a model of a material used for simulation analysis as an example.

Fig. 6C is a diagram showing an example of a die for press working assumed in the simulation analysis.

Fig. 6D is a view showing a simple die model obtained by cutting out a constricted flange portion of a die model of press working assumed in simulation analysis.

Fig. 7 is a graph showing the sheet thickness reduction rate obtained from the results of the simulation analysis.

Fig. 8 is a view illustrating 3-point bending crushing test conditions.

Detailed Description

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the present specification and the drawings, components having substantially the same functional configuration are denoted by the same reference numerals, and redundant description thereof is omitted.

<1 > embodiment 1 >

[ outline of Steel sheet construction ]

First, a schematic configuration of a blank 100 according to embodiment 1 of the present invention will be described with reference to fig. 1A and 1B. Fig. 1A is a perspective view showing an example of a blank 100 according to the present embodiment. Fig. 1B is a perspective view showing an example of the molded article 200 according to the present embodiment. The blank 100 of the present embodiment is a workpiece that is finally processed into a molded article having a predetermined shape through various kinds of processing. The blank 100 is formed into a predetermined plate shape by cutting from a steel plate, which is a flat plate-like member, for example. Examples of the cutting process include known cutting techniques such as punching press process and laser process, and are not particularly limited.

The blank 100 cut out from the steel sheet is processed into a molded article having a predetermined shape by, for example, cold forming. The machined shape of the blank 100 will be described in detail later, but the blank 100 is machined by cold forming into a shape having a constricted flange portion (corresponding to the constricted flange portion 221 in fig. 1B described later). Examples of cold forming include known cold forming techniques such as press bending and press drawing, and are not particularly limited.

As shown in fig. 1A, the blank 100 has a main portion region 110 and a convex portion region 113. The main portion region 110 is a region mainly constituting the blank 100, and has the same properties as the steel plate from which the blank 100 is cut. Main portion region 110 may be a steel material having a tensile strength of 1100MPa or more. Further, main portion region 110 may be a steel material having a tensile strength of 1100MPa or more and 2000MPa or less.

The convex portion region 113 is a region in which: in the blank 100, a part of the outer edge 111 protrudes outward in a planar view substantially perpendicular to the plate surface of the blank 100, that is, in the in-plane direction of the blank 100. The convex portion region 113 is a region which becomes a constricted flange portion after molding. In other words, at least a part of the molded convex region 113 constitutes at least a part of the shrunk flange portion. The softened portion 120 is at least partially formed in the convex region 113. Details of the softening unit 120 will be described later. The blank 100 may have at least two or more convex regions 113 in which the softened portions 120 are formed.

[ problems in the shape and formation of the molded article ]

Next, the shape of the molded product 200 and the problem during molding will be described with reference to fig. 1B. The blank 100 having a predetermined shape is formed into a molded article 200 having a predetermined shape by, for example, cold forming. As shown in fig. 1B, the molded article 200 has a box shape, and includes a web portion 210 as a bottom surface, a flange portion 220 standing from the bottom surface, and a constricted flange portion 221, as an example. Here, the molded article 200 includes a finished product that is finished in a predetermined shape by processing the blank 100, and a semi-finished product that requires additional processes such as processing and treatment.

For example, the molded article 200 includes a flange portion 220 formed by bending the outer peripheral side of the blank 100. The flange portion 220 has a constricted flange portion 221 that deforms while receiving a compressive stress at a portion thereof during molding.

In a molded article having such a shrunk flange portion 221, problems may occur due to the shape thereof. That is, due to the compressive stress during molding, a part of the blank 100 (the convex region 113) is deformed out of plane during molding, and as a result, is deformed in a wave shape. When the deformed portion is further crushed by the mold, a fine unevenness, that is, a wrinkle is generated after molding. The wrinkles generated in the molded article may cause deterioration in the appearance and dimensional accuracy of the molded article or deterioration in the welding quality.

In particular, when a high-strength steel sheet is used as the base material of the blank 100, the steel has a high yield stress and poor ductility, and thus the formability is degraded. Further, since high-strength steel sheets are often used in order to reduce the weight and are thinned, the surface rigidity of the steel sheets is reduced. For these reasons, when the molded product 200 having the constricted flange portion 221 is molded using the blank 100 of the high-strength steel sheet, wrinkles after molding are likely to occur in the constricted flange portion 221, and the height of the wrinkles and the increase in the thickness of the wrinkled portion are also increased. As a result, the appearance and dimensional accuracy of the molded product 200 are likely to be deteriorated, and the welding quality is likely to be deteriorated. In particular, when the base material of the blank 100 is a steel material having a tensile strength of 1100MPa or more, the influence of wrinkles is increased.

Therefore, the present inventors have conducted intensive studies and as a result, have conceived that: the softened portion 120 is formed in the convex portion region 113 of the blank 100 corresponding to the constricted flange portion 221 of the molded article 200. Namely, the present inventors thought: by forming the softening portion 120 in the convex region 113, the yield point of the region to be the contracted flange portion 221 is lowered, and the out-of-plane deformation at the time of molding is suppressed, and the occurrence of wrinkles in the contracted flange portion 221 is suppressed.

In addition, through the above molding process, in the shrinkage bead portion, a difference in vickers hardness occurs in the ridge line direction thereof. In addition, in the contraction flange portion, a difference in plate thickness occurs in the ridge line direction thereof. In this regard, the constricted flange portion is different from, for example, a bent portion in a molded article obtained by bending a plate material in an out-of-plane direction. The ridge line direction of the flange portion can be said to be a direction parallel to an intersection line of virtual planes that expand the plate surfaces of two flange portions adjacent to the contracted flange portion.

For example, in the constricted flange portion 221 of the molded article 200 illustrated in fig. 1B, the vickers hardness of the constricted flange portion 221 increases and the plate thickness of the constricted flange portion 221 increases as the distance from the web portion 210 in the ridge line direction of the constricted flange portion 221 increases.

[ softened portion ]

The softened portion 120 is a softened region formed at least partially in the convex region 113 of the blank 100. The vickers hardness of the softened portion 120 is set lower than the vickers hardness of the main portion region 110 of the blank 100. In particular, the vickers hardness of the softened portion 120 may be set so that the ratio of the vickers hardness to the main portion region 110 of the blank 100 is 0.4 to 0.9.

By setting the vickers hardness of the softening portion 120 to 0.9 or less of the vickers hardness of the main portion region 110, the following effects can be obtained: the yield point of the convex portion region 113 is locally lowered, and the occurrence of wrinkles in the shrunk flange portion 221 of the molded product is suppressed. On the other hand, by setting the vickers hardness of the softening portion 120 to 0.4 or more with respect to the vickers hardness of the main portion region 110, the strength of the molded article can be sufficiently ensured.

The hardness measurement conditions are as follows. A sample including the convex region 113 of the blank 100 was collected, and a sample of the measurement surface was prepared for vickers hardness test. Preparation method of the measurement surface was carried out in accordance with JIS Z2244: 2009. After polishing the measurement surface with #600 to #1500 silicon carbide sandpaper, a mirror surface was finished with a solution obtained by dispersing diamond powder having a particle size of 1 to 6 μm in a diluent such as ethanol or pure water. Vickers hardness test was performed by JIS Z2244: 2009 by the method described herein. The vickers hardness of the sample prepared with the measurement surface was measured using a micro vickers hardness tester with a test load of 1kgf (9.8N). For example, a region having a vickers hardness of 0.9 or less with respect to an average value of vickers hardnesses at a plurality of regions in the central portion of the main portion region 110 may be used as the softening portion 120.

The tensile strength of the softened portion 120 may be set to 1000MPa or less. This can suppress the strength of the softening portion 120, and can further suppress the occurrence of wrinkles.

Examples of a method for forming the softened portion 120 include the following methods: the blank 100 is locally tempered and softened using a known local heating technique such as laser heating or high-frequency heating. In another example, the blank 100 may be softened by partially tempering the blank by a hot forming technique such as local hot forming. The method of forming the softened portion 120 may be any method as long as the hardness can be locally reduced, and may be a method other than tempering by heating. For example, the billet 100 may be partially decarburized.

The softened portion 120 may not be formed in all the convex regions 113 of the blank 100. The softened portion 120 may be formed in the convex portion region 113 where wrinkles are expected to occur, taking into consideration the shape, size, and the like of the shrunk flange portion 221 after molding.

The softened portion 120 may also be formed in a region including the outer edge 111 of the convex region 113. In other words, the softened portion 120 may be formed at least in a part of the outer edge 111 of the convex region 113. By forming the softening portion 120 in the region including the outer edge 111 of the convex portion region 113, the vicinity of the outer edge 111 where wrinkles are likely to occur is softened, and the occurrence of wrinkles can be further suppressed.

In the convex region 113, the softened portion 120 may extend along the in-plane direction of the blank 100 (the direction orthogonal to the thickness direction). Specifically, the softening portion 120 may include the outer edge 111 and be formed in the in-plane direction across a distance of 60mm from the outer edge 111, preferably across a distance of 40mm from the outer edge 111.

By the softening portion 120 expanding in the in-plane direction, a sufficient softened region in the convex region 113 can be secured, and the occurrence of wrinkles in the constricted flange portion 221 can be further suppressed. Further, the softened portion 120 is formed in the in-plane direction over a predetermined range from the outer edge 111, and thus high strength as a molded article can be maintained while securing a softened region. The softened portion 120 may be formed only in the convex region 113, or may be formed up to the main portion region 110 if it is in a range of 50mm from the convex region 113 to the outside.

When the blank 100 is formed into a predetermined shape, in the case of press working (drawing, bending) in which the blank 100 may move, the forming range of the softening portion 120 may be determined in consideration of the amount of movement of the blank 100 during forming. The depth of the softened portion 120 in the thickness direction is not particularly limited, and the softened portion 120 may be formed over the entire thickness direction.

The softening portion 120 may be formed of another member having a different material from the main portion region 110 of the blank 100. For example, the other member may be attached to the blank 100 by welding or the like to form the softened portion 120, with the vickers hardness of the other member set to be lower than the vickers hardness of the main portion region 110 of the blank 100. In this case, the other member has a convex shape, and becomes the constricted flange portion 221 after the molding of the blank 100.

According to the present embodiment, by forming the softening portion 120 in the convex region 113, the yield point of the region to be the constricted flange portion 221 is lowered, and out-of-plane deformation at the time of molding is suppressed. That is, by forming the softened portion 120, plastic deformation of the convex portion region 113 is easily generated, and the convex portion region 113 and the mold are adapted to each other at an early stage after the start of molding. As a result, out-of-plane deformation of the constricted flange portion 221 can be suppressed. Therefore, the occurrence of wrinkles in the shrunk flange portion 221 of the molded product 200 can be suppressed, and as a result, the influence of wrinkles in the molded product 200 can be reduced. In particular, deterioration in the appearance or dimensional accuracy of the shrunk flange 221 of the molded article 200 can be reduced.

<2 > embodiment 2 >

Next, a blank 300 according to embodiment 2 of the present invention will be described. The blank 300 of the present embodiment is different from the blank of embodiment 1 in that it is formed into a seat cushion frame by molding. In the description of the present embodiment, the configuration common to that of embodiment 1 will not be described.

The blank 300 and the seat cushion frame 400 according to the present embodiment will be described with reference to fig. 2A and 2B. Fig. 2A is a plan view showing an example of the blank 300 according to the present embodiment. Fig. 2B is a perspective view showing an example of the seat cushion frame 400 according to the present embodiment.

The blank 300 cut out of the steel sheet is further processed by cold forming into a seat cushion frame 400 (side frame) which is a molded article having a predetermined shape. Specifically, the blank 300 is formed into a shape having a constricted flange portion (corresponding to the constricted flange portion 421 in fig. 2B described later) by cold forming such as press bending or press drawing. The seat cushion frame 400 is a part of a seat frame, which is an inner frame of the vehicle seat, and is a member provided on a side of a seat cushion for supporting a thigh or a hip of a seat occupant.

As shown in fig. 2A, the blank 300 has a main portion region 310 and a convex portion region 313. The convex portion region 313 is a region in which: in the blank 300, a part of the outer edge 311 protrudes outward in a planar view substantially perpendicular to the plate surface of the blank 300, that is, in the in-plane direction of the blank 300. The convex portion region 313 is a region which becomes a constricted flange portion after molding. In other words, at least a part of the molded convex region 313 constitutes at least a part of the shrunk flange portion. A softened portion 320 is formed in the convex region 313.

As shown in fig. 2B, the seat cushion frame 400 includes a frame body 410 and a frame flange portion 420 provided upright from an end of the frame body 410. The frame flange portion 420 has a contracted flange portion 421. The seat cushion frame 400 may take on various shapes depending on the configuration of the seat frame.

For example, the seat cushion frame 400 includes a frame flange portion 420 formed by bending the outer peripheral side of the blank 300. The convex portion 313 of the blank 300 is deformed while receiving a compressive stress at the time of molding, and thereby the frame flange portion 420 is formed with the contracted flange portion 421. In the contracted flange portion 421 of the seat cushion frame 400, wrinkles may be generated by molding as described above.

As shown in fig. 2A, a plurality of convex regions 313 can be formed in the blank 300. In addition, the convex portion 313 can take various convex shapes in consideration of the shape of the seat cushion frame 400 after molding. The convex portion region 313 of the present embodiment will be described below with reference to fig. 3.

Fig. 3 is a diagram for explaining the convex portion region 313 of the blank 300, and is an enlarged view of the region X in fig. 2A. As shown in fig. 3, the convex portion 313 is a region where a part of the outer edge 311 of the blank 300 is convex toward the outside. An arc parallel to the plate surface of the blank 300 is set in the outer edge 311 of the blank 300 by a known calculation method, and the convex portion region 313 is determined based on the curvature radius and the opening angle of the arc. The arc is an arc formed by connecting 3 points separated by 1mm along the outer edge 311. As shown in fig. 3, the radius of curvature R of the arc for determining the convex portion region 313 is 150mm or less, and the opening angle θ is 60 degrees or more and 120 degrees or less. The convex region 313 is determined by the above method, and the softened portion 320 is formed in the convex region 313.

As described above, by determining the convex region 313 and forming the softened portion 320 in the convex region 313, the softened portion 320 can be provided in the convex region 313 where wrinkles are supposed to occur. This can effectively suppress the occurrence of wrinkles in the contracted flange portion 421 of the seat cushion frame 400, and can maintain high strength of the molded seat cushion frame 400.

The blank 300 may have at least two or more convex regions 313 with the softened portions 320 formed therein. The main portion region 310 of the blank 300 may be a steel material having a tensile strength of 1100MPa or more. Further, the main portion region 310 of the blank 300 may be a steel material having a tensile strength of 1100MPa or more and 2000MPa or less.

According to the present embodiment, by forming the softening portion 320 in the convex portion region 313, the yield point of the region to be the contracted flange portion 421 is lowered, and the out-of-plane deformation at the time of molding is suppressed. As a result, the occurrence of wrinkles in the contracted flange portion 421 can be suppressed in the seat cushion frame 400, which is a molded product. This can reduce the influence of the wrinkles on the seat cushion frame 400. In particular, deterioration in the appearance or dimensional accuracy of the contracted flange portion 421 of the seat cushion frame 400 can be reduced.

In the present embodiment, an example of molding the blank 300 into the seat cushion frame 400 has been described, but the present invention is not limited to the seat cushion frame as long as it is a molded product having a constricted flange portion. For example, it may be applied to a seat back frame.

[ application example of skeleton member according to embodiment of the present invention ]

The preferred embodiments of the present invention have been described in detail above. Hereinafter, an application example of the frame member molded using the blanks 100 and 300 according to any embodiment of the present invention will be described with reference to fig. 4. Fig. 4 is a diagram showing an automobile frame 500 as an example of a frame member formed by applying the blanks 100, 300 according to the embodiment of the present invention. The frame member formed using the blanks 100 and 300 can constitute the automobile frame 500 as a cab frame or an impact absorbing frame. Examples of the cab frame include a ceiling side rail 501, an a-pillar lower member 507, an a-pillar upper member 505, a pedal reinforcement 511, a floor cross member 513, and a front window sill 515.

Examples of the frame member of the impact absorbing frame include a rear side member 503, a bumper reinforcement 509, and the like.

The frame member molded using the blanks 100 and 300 according to any of the embodiments of the present invention can suppress the occurrence of wrinkles in the shrunk flange portion. This can reduce the influence of wrinkles even in the frame member.

Next, an example of a member molded using the blank 100 according to any one of the embodiments of the present invention will be described with reference to fig. 5A and 5B. Fig. 5A is a diagram showing an example of a member molded using the blank 100 of the present embodiment. Fig. 5B is a diagram showing an example of application of a member molded using the blank 100 of the present embodiment. The spacer 610 is an example of a member molded by using the blank 100 of the present embodiment. The partition 610 is a substantially box-shaped member having one open surface. The partition wall 610 forms a partition wall inside the hollow frame member, whereby the rigidity and the collision performance of the frame member are further improved.

As shown in fig. 5A, the spacer 610 as an example has a box shape, and includes a web portion 611 as a bottom surface portion, a flange portion 613 as a vertical wall portion provided upright from an end portion of the bottom surface portion, and a corner portion 615. A softened portion 620 is formed at least partially in the corner portion 615. The web portion 611 and the flange portion 613 are formed by the main portion area 617.

The flange portion 613 has a 1 st flange portion 613a as a 1 st vertical wall portion and a 2 nd flange portion 613b as a 2 nd vertical wall portion. The corner portion 615 is provided between the 1 st flange portion 613a and the 2 nd flange portion 613b so as to connect the 1 st flange portion 613a and the 2 nd flange portion 613b while being bent. The 2 nd flange portion 613b is provided from an end of the corner portion 615 in a direction substantially perpendicular to the 1 st flange portion 613 a. One end of the corner portion 615 in the ridge line direction is connected to the web portion 611.

As shown in fig. 5A, in the separator 610, at least two corner portions 615 are formed. The separator 610 has at least two or more corner portions 615 where the softened portions 620 are formed. A part of the corner portion 615 is formed as a part of the above-described constricted flange portion.

The vickers hardness of the softened portion 620 is set lower than the vickers hardness of the web portion 611 of the separator 610 or the main portion area 617 of the flange portion 613. In particular, the vickers hardness of the softened portion 620 may be set so that the ratio of the vickers hardness to the main portion area 617 of the separator 610 is 0.4 or more and 0.9 or less.

By setting the vickers hardness of the softened portion 620 to 0.9 or less of the vickers hardness of the main portion 617, an effect of suppressing breakage of the corner portion 615 of the molded product at the time of collision can be obtained. Further, by setting the vickers hardness of the softening portion 620 to 0.9 or less of the vickers hardness of the main portion region 617, an effect of suppressing the occurrence of wrinkles can be obtained. On the other hand, by setting the vickers hardness of the softening portion 620 to 0.4 or more with respect to the vickers hardness of the main portion region, the strength of the molded article can be sufficiently ensured.

The main region 617 of the diaphragm 610 may be a steel material having a tensile strength of 1100MPa or more. The softened portion 620 may have a tensile strength of 1000MPa or less.

The spacer 610 is provided inside the square tubular frame member 630 along the short side direction of the frame member 630. The frame member 630 has a pair of 1 st wall portions 631, corner portions 633 provided at the ends of the 1 st wall portions 631 in the short side direction, and a pair of 2 nd wall portions 635 provided along the direction orthogonal to the 1 st wall portions 631 from the corner portions 633. The flange portion 613 of the spacer 610 is attached to the inner surface side of the 1 st wall portion 631 and the 2 nd wall portion 635. Further, the corner 615 of the spacer 610 is attached to the curved inner side of the corner 633 of the frame member 630.

The separator 610 is molded from the blank 100 of the present embodiment, and a softened portion 620 is provided at a corner portion 615 of the separator 610. Therefore, when a load is input to the frame member 630, the diaphragm 610 can be suppressed from breaking starting from the corner portion 615 as the contracted flange portion.

Further, since the separator 610 is molded from the blank 100 of the present embodiment, the occurrence of wrinkles in the corner portion 615 as the constricted flange portion can be suppressed. This improves the adhesion between the separator 610 and the frame member 630, and reduces the influence of wrinkles on the separator 610.

Examples

(example 1)

In order to confirm the influence of the blank material of the above embodiment on wrinkles, simulation analysis of press forming was performed. The simulation analysis result will be described with reference to fig. 6A, 6B, 6C, and 6D. Fig. 6A is a model of a material for simulation analysis as comparative example 1. Fig. 6B is a model of a blank for simulation analysis as an example. Fig. 6C is a diagram showing an example of a die for press working assumed in the simulation analysis. Fig. 6D is a simple mold model in which a corner portion forming the constricted flange portion is cut out of the mold shown in fig. 6C. This analysis was performed using the simple mold model of fig. 6D.

As shown in fig. 6A, in the comparative example according to the present invention, a blank mold 700A having a quarter-circle shape (corresponding to a convex portion region) is used. In the comparative example, the region 710 corresponding to the steel material having the tensile strength of 1180MPa which becomes the base material is provided, and the curvature radius R of the outer edge 713 in a plan view is 120 mm. On the other hand, as shown in fig. 6B, in the example of the present invention, a quarter-circle-shaped blank mold 700B was used as in the comparative example. In the embodiment, the region 720 serving as a softened portion is provided on the outer peripheral side of the quadrant, and the region 710 corresponding to a steel material serving as a base material and having a tensile strength of 1180MPa is provided on the center side of the quadrant.

Further, in the embodiment, the vickers hardness of the region 720 was changed to perform the simulation. In example 1, the vickers hardness of the region 720 corresponding to the softened portion was set to 0.83 with respect to the vickers hardness of the region 710. This corresponds to the case where the softened portion is a steel material having a tensile strength of 980 MPa. In example 2, the vickers hardness of the region 720 was set to 0.66 with respect to the region 710. This corresponds to the case where the softened portion is a steel material having a tensile strength of 780 MPa. In example 3, the vickers hardness of the region 720 was set to 0.5 with respect to the vickers hardness of the region 710. This corresponds to the case where the softened portion is a steel material having a tensile strength of 590 MPa. The outer edge 713 of the mold of the example had a curvature radius R of 120mm in plan view as in comparative example 1, and the region 720 corresponding to the softened portion included the outer edge 713 of the mold and existed up to a position 60mm away from the outer edge 713 of the mold. Therefore, the entire area of the vertical wall is constituted by the region 720. In the example and comparative example 1, the thickness of the mold was the same.

As shown in fig. 6D, a simulation of press working of a blank was performed using the die models a ', B ', and C '. The die patterns a ', B ', and C ' are simple patterns corresponding to parts of the die a, the pad B, and the punch C in fig. 6C, respectively. The present inventors held the center side of the pattern of the blank by a die pattern C ' (punch) and a die pattern B ' (spacer), and moved it toward a die pattern a ' (die) to deform the blank pattern. Namely, the following simulation analysis was performed: the outer peripheral side of the quarter-circle shape shown in fig. 6A and 6B is bent and compressed to be deformed to form a flange, and the flange is formed into a shape of a molded article having a constricted flange portion. Further, the sheet thickness reduction rates of the shrunk flange portions of the respective molds after molding were compared. Here, the sheet thickness reduction rate indicates a reduction rate of the sheet thickness after the forming with respect to the sheet thickness before the forming in the shrink flange portion. The maximum value of the sheet thickness reduction rate of the molded article is set as the sheet thickness reduction rate.

Fig. 7 is a graph showing the sheet thickness reduction rate of the shrunk flange portion of the post-press-forming model obtained as a result of the simulation analysis. As shown in FIG. 7, the reduction rate of the plate thickness in examples 1 to 3 was about 16 to 18% as compared with that in comparative example. As a result, it was found that the rate of reduction in the thickness of the shrunk flange portion can be reduced by using the blank according to any of the embodiments of the present invention. It is also found that if the ratio of the vickers hardness of the softened portion to the vickers hardness of the main portion region is 0.9 or less, the sheet thickness reduction rate can be greatly reduced.

The decrease in the sheet thickness reduction rate indicates that the sheet thickness variation after the forming of the shrunk flange portion can be suppressed, and as a result, indicates that the generation of wrinkles due to the sheet thickness variation can be suppressed. That is, with the blank according to any of the embodiments of the present invention, the occurrence of wrinkles in the molded article having the constricted flange portion can be suppressed.

Further, as shown in fig. 7, in examples 1 to 3, since the change in the sheet thickness reduction rate was small, it was found that even if the ratio of the vickers hardness of the softened region to the vickers hardness of the main region was decreased from 0.9, the decrease amount of the sheet thickness reduction rate was small. That is, from the viewpoint of suppressing wrinkles, the ratio of the vickers hardness of the softened portion to the vickers hardness of the main portion region is preferably 0.9 or less. From the viewpoint of the effect of suppressing wrinkles and the strength of the member, the ratio of the vickers hardness of the softened portion to the vickers hardness of the main portion region is preferably 0.4 or more.

(example 2)

In order to evaluate the performance of the separator 610 as a member of the present invention, a 3-point bending crush test was performed. The test results will be described with reference to fig. 8. Fig. 8 is a view illustrating 3-point bending crushing test conditions. As shown in fig. 8, the impactor I was caused to collide with the frame member 630 including the separator 610 of the present invention along the direction of the arrow in fig. 8, and the presence or absence of fracture at the corner portion 615 of the separator 610 was evaluated. The collision position is a position where the partition plate 610 is provided, that is, a substantially central position in the longitudinal direction of the frame member 630. Further, it was examined whether or not the frame member 630 was broken when the collision speed was 64km/h and the amount of the impact tool I intruding into the frame member was 10 mm.

In example 4, the main portion area 617 of the diaphragm 610 is a steel material having a tensile strength of 1180 MPa. The hardness is controlled so that the strength of the softened portion 620 provided at the corner portion 615 is 980MPa in terms of tensile strength, i.e., 0.83 in terms of vickers hardness of the main portion region 617. In comparative example 2, the softened portion was not provided at the corner, and the entire separator was made of a steel material having a tensile strength of 1180 MPa. The dimension of the frame member 630 was a rectangular tube shape of 100mm in the vertical direction × 100mm in the horizontal direction in a cross section along the short side direction, and the plate thickness was 0.8 mm. The thickness of the separator was also 0.8 mm. Table 1 shows the evaluation results.

[ Table 1]

Sampling	Corner softening part	Corner fracture at 10mm intrusion
			Comparative example 2	Is free of	Is provided with
Example 4	Is provided with	Is free of

As shown in table 1, in comparative example 2 in which no softened portion was provided at the corner, when the impactor I intruded 10mm, breakage occurred at the corner of the separator. On the other hand, in example 4, even when the impactor I intruded 10mm, no fracture occurred in the separator 610. In this way, by providing the corner portion 615 with the softened portion 620 softened more than the main portion region 617 and setting the strength of the softened portion 620 to 0.9 or less of the vickers hardness of the main portion region 617, it is possible to suppress the breakage of the corner portion 615 of the bulkhead 610.

The preferred embodiments of the present invention have been described in detail with reference to the accompanying drawings, but the present invention is not limited to such examples. It is obvious to those having ordinary knowledge in the art to which the present invention pertains that various modifications and alterations can be made within the scope of the technical idea described in the claims, and it should be understood that they also belong to the technical scope of the present invention.

Availability in the industry

The present invention is industrially useful because it can provide a blank that can suppress the influence of wrinkles generated in the shrunk flange portion and the like.

Description of the symbols

100. 300, and (2) 300: a blank; 110. 310: a main portion region; 111. 311: an outer edge; 113. 313: a convex region; 120. 320, and (3) respectively: a softening section; 200: a molded article; 210: a web portion; 220: a flange portion; 221. 421: shrinking the flange part; 400: a seat cushion frame; 610: a partition (member); 611: a web portion (bottom surface portion); 613: a flange portion; 613 a: a 1 st flange portion (1 st vertical wall portion); 613 b: a 2 nd flange portion (a 2 nd vertical wall portion); 615: corner portions (constricted flange portions); 617: a main portion region; 620: a softening part.