阅读说明：本技术 弯曲模及弯曲模的制造方法 (Bending die and method for manufacturing bending die ) 是由 刘吉宁 中里和彦 羽部贵昭 于 2018-10-10 设计创作，主要内容包括：以提出一种即使产品的形状长、另外即使是在三维空间内自由地弯曲的形状的产品也能够不发生压曲地制作的弯曲模为目的,弯曲模(1)具有通过使包含具有凹部的大致圆形形状的第1闭合曲线(C1)的轮廓(5)在三维空间内假想地连续移动而形成的平滑的形状,所述凹部的开口宽度(b)比凹部的槽宽度(a)短,由所述凹部形成管嵌入部(2),所述形状利用三维打印的技术在真实空间中实体化而制成。(In order to provide a bending die which can be produced without buckling even if the shape of a product is long and even if the product has a shape which can be freely bent in a three-dimensional space, a bending die (1) has a smooth shape which is formed by virtually and continuously moving in the three-dimensional space a contour (5) including a1 st closed curve (C1) having a substantially circular shape with a recess whose opening width (b) is shorter than the groove width (a) of the recess, and a tube fitting section (2) is formed by the recess, and the shape is formed by a three-dimensional printing technique and is materialized in a real space.)

1. A bending die for forming by inserting a tube, characterized in that,

the bending die has a smooth shape formed by virtually and continuously moving a contour including a1 st closed curve in a three-dimensional space, the 1 st closed curve being a substantially circular shape having a recess with an opening width shorter than a groove width of the recess, a tube insertion portion being formed by the recess, the shape being made solid in a real space by a three-dimensional printing technique.

2. Bending die according to claim 1,

the virtual continuous movement in the three-dimensional space is a simple parallel movement of the contour, a turning or tilting movement combining a change in the direction of the contour surface and the parallel movement, a twisting movement combining an in-plane rotation and the parallel movement of the contour surface, or a combination thereof.

3. Bending die according to claim 1,

two areas of the profile adjacent to both sides of the opening of the recess are gentle curves or straight lines, and two areas of the profile adjacent to both sides of the inside portion of the opening of the recess are gentle curves or straight lines.

4. Bending die according to claim 1,

the bending die is formed by connecting a plurality of unit bending dies in series, and each unit bending die is provided with a connecting portion at an end portion thereof for connecting to an adjacent unit bending die.

5. Bending die according to claim 1,

the contour formed by the 1 st closed curve includes a2 nd closed curve formed by a closed curve inside, and the 2 nd closed curve forms a hole for a heat medium.

6. Bending die according to claim 5,

the 2 nd closed curve has a protrusion inside.

7. A bending die according to any one of claims 1 to 6,

the bending die is made of metal through a three-dimensional printing technology.

8. A method for manufacturing a bending die, characterized in that,

a bending die for forming a pipe by fitting is designed to have a smooth shape formed by virtually and continuously moving the contour of a1 st closed curve including a substantially circular shape having a concave portion in a three-dimensional space, and data of the shape is obtained.

9. The manufacturing method of a bending die according to claim 8,

a plurality of bending dies is made by the technique of three-dimensional printing, which are connected together to make a bending die for the product of the strip.

Technical Field

In order to manufacture a bent pipe such as an oil delivery pipe of an automobile, for example, there is a technique of heating a thermoplastic resin pipe and placing the heated pipe in a bending die to mold the pipe. The present invention relates to a bending die used for forming such a bent pipe and a method for manufacturing the bending die.

Background

A bending die is used to form a pipe made of a thermoplastic resin while being bent into a predetermined shape. The bending die is formed into a desired shape by, for example, manually combining a plurality of iron plates and performing welding or the like. Further, a flat iron plate is also subjected to press working to produce a bending die having a desired shape.

Patent document 1 also discloses the following technique.

A bending die having a desired shape is manufactured by extruding an aluminum material to manufacture a U-shaped tube having a U-shaped cross section, fitting a rod-shaped flexible core material made of a thermoplastic resin having a predetermined hardness into the U-shaped tube, bending the U-shaped tube by a bending machine in this state, and then taking out the core material. Then, a thermoplastic resin pipe extruded into a straight pipe shape is fitted into the bending die and attached, and the pipe is subjected to a heat treatment and bending processing to obtain a bent pipe having a predetermined bent shape.

As a prior art to this technique, patent document 1 also discloses a bending die having a rectangular shape whose upper surface is open in cross section.

Patent document 2 discloses a bending die formed by milling a groove having a semicircular cross section on an uneven upper surface. Further, patent document 3 discloses a bending die for forming a groove having a substantially C-shaped cross section by punching.

Disclosure of Invention

Problems to be solved by the invention

The bending die for inserting the thermoplastic resin tube and forming the thermoplastic resin tube into a predetermined shape has been conventionally manufactured by a manual operation as described above. However, when a bending die having a desired shape is produced by combining a plurality of iron plates by a manual operation and performing a welding process or the like, there is a problem that variations occur in the shape and size of the bending die depending on the skill of an operator or the like. Therefore, a method of manufacturing a bending die without depending on the skill of the worker or the like is sought.

When a pipe made of a thermoplastic resin is manually inserted into a mold having a U-shaped cross section and heated to produce a product having a predetermined shape, the following steps are conventionally performed: the pipe is heated in advance by adding a heating medium (gas or liquid), and the heated pipe is manually placed in a mold. In such a method, since the work of putting the hot pipe into the mold by hand is dangerous to burn, the workability is poor. Therefore, a method of automatically inserting a pipe into a bending die without relying on manual work is also being sought.

The bending die and the method for manufacturing the bending die disclosed in patent documents 1, 2, and 3 are proposed to solve the above-described problems. However, these proposals have problems that have not yet been solved. For example, when a bending die is manufactured from a flat plate by press working, there is a limitation on the shape of the bending die. Further, it is impossible to produce a bending die having a shape such that a portion thereof which is hidden from view when the bending die is viewed from a specific direction is not visible. That is, according to these conventional techniques, it is not possible to produce a bending die having a shape that is sequentially bent in orthogonal x-axis, y-axis, and z-axis directions. For example, it is difficult to form a bending die having a complicated shape as described above by a method disclosed in patent document 1, that is, a method of bending an aluminum pipe in which a core material is put, and then removing the core material. In addition, the bending die of patent document 2 has the same problem in the case of manufacturing the bending die by milling, and also has a problem in that a large amount of milling chips are generated. The same problem arises with the shape of the bending die in the case of manufacturing the bending die by punching in patent document 3.

The bending die of the prior art is premised on inserting a pipe into the bending die by manual work. The thermoplastic resin pipe is inserted into a bending die having a complicated shape for producing a product having a complicated shape by the judgment and skill of an operator. However, in the case of a product made of a pipe of a considerable length, for example, a product exceeding 2 m, it is not easy to embed into a bending die by a manual work, and it is practically impossible. Further, since the work of inserting the heated thermoplastic resin tube into the bending die may cause a burn, it is desirable to automate the process.

In addition, when a thermoplastic resin pipe is inserted into a bending die, the pipe is heated in advance with a heat medium, but when the temperature of the bending die is not controlled as in the prior art, the pipe may be cooled more quickly than expected after the pipe is inserted into the bending die, which may cause deformation of the product. In addition, cooling of the product before it is removed may be undesirably slow, resulting in an impact on the work schedule.

Therefore, the first object of the present invention is to provide a bending die which can be manufactured even if the shape of a product manufactured by fitting a thermoplastic resin tube into a bending die exceeds 2 m and even if the product has a complicated shape which can be freely bent in a three-dimensional space. The invention provides a bending die which can insert a thermoplastic resin pipe by using an automatic inserting device in a2 nd task. Another object of the present invention is to provide a bending die capable of controlling temperature in the 3 rd step. The 4 th object of the present invention is to provide a manufacturing method for manufacturing such a bending die.

Means for solving the problems

The above-described problems are solved by a bending die and a method for manufacturing a bending die described in [ 1 ] to [ 9 ] below.

[ 1 ] A bending die for fitting a pipe to perform forming, wherein the bending die has a smooth shape formed by virtually and continuously moving a contour (Japanese: プロファイル) including a1 st closed curve having a substantially circular shape with a recess whose opening width is shorter than a groove width of the recess in a three-dimensional space, and a pipe fitting portion is formed by the recess, and the shape is materialized (Japanese: actualization) in a real space using a three-dimensional printing technique.

In the bending die according to the above [ 1 ], the virtual continuous motion in the three-dimensional space is a simple parallel motion of the contour, a turning or tilting motion in which a change in the direction of the contour surface is combined with the parallel motion, a twisting motion in which an in-plane rotation of the contour surface is combined with the parallel motion, or a motion in which these motions are combined.

[ 3 ] in the bending die according to the above [ 1 ], two regions of the contour adjacent to both sides of the opening of the recess are gentle curves or straight lines, and two regions of the contour adjacent to both sides of the back side portion of the opening of the recess are gentle curves or straight lines.

[ 4 ] in the bending die according to the above [ 1 ], the bending die is formed by connecting a plurality of unit bending dies in series, and each of the unit bending dies includes a connecting portion at an end portion thereof for connecting to an adjacent unit bending die.

In the bending die according to the above [ 1 ], the contour formed by the above-described 1 st closed curve includes a2 nd closed curve formed by a closed curve inside, and the hole for the heat medium is formed by the 2 nd closed curve.

[ 6 ] in the bending die according to [ 5 ], the 2 nd closed curve has a protrusion inside.

[ 7 ] the bending die according to any one of [ 1 ] to [ 6 ] above, wherein the bending die is formed by a three-dimensional printing technique using a metal as a material.

[ 8 ] A method for manufacturing a bending die, wherein a smooth shape formed by virtually and continuously moving the contour of a1 st closed curve including a substantially circular shape having a concave portion in a three-dimensional space is designed for a bending die for fitting a pipe and forming, data of the shape is obtained, and the bending die of the shape is manufactured by a three-dimensional printing technique based on the data.

The method of manufacturing a bending die according to the above [ 8 ], wherein a plurality of bending dies are formed by a three-dimensional printing technique, and the plurality of bending dies are connected to each other to manufacture a bending die for a long product.

Effects of the invention

According to the bending die of the present invention, even if the shape of the product exceeds 2 m, and even if the product has a complicated shape which can be freely bent in a three-dimensional space, the product can be manufactured. In addition, it is possible to obtain a bending die in which the position of the opening of the concave portion of the bending die can be optimized to avoid buckling phenomenon at the time of tube insertion, and once the inserted tube is not easily detached.

Drawings

Fig. 1 is a conceptual perspective view showing an embodiment of a bending die (unit bending die) of the present invention.

Fig. 2 is a conceptual perspective view showing another embodiment of a bending die (unit bending die) according to the present invention.

Fig. 3 is a front view of an example of the outline.

Fig. 4 is a conceptual perspective view of the unit bending die of fig. 1 and 2 when they are connected.

Fig. 5 is a front view showing an example of the outline in the case of forming the holes for the heat medium.

Fig. 6 is a conceptual perspective view showing an embodiment of a bending die in which a hole for a heat medium is formed in a cutaway manner.

Fig. 7 is a conceptual perspective view showing an embodiment of a bending die formed by connecting a plurality of unit bending dies and three-dimensionally freely bending the dies.

Fig. 8 is a front view showing some preferred examples of the shape of the outline, particularly the shape of the 2 nd closed curve.

Fig. 9 is a view showing measurement examples of temperature changes at three points in the case of molding a thermoplastic resin tube using a solid bending die a formed from the profile of fig. 8 (a) and in the case of molding a thermoplastic resin tube using a bending die B having two holes for heat medium formed from the profile of fig. 8 (c).

Fig. 10 is a view showing temperature measurement points a1, a2, and A3 of bending die a and temperature measurement points B1, B2, and B3 of bending die B.

Fig. 11 is a view showing measurement examples of temperature changes at three points of the pipe in the case where the bending die B having the hole for the heat medium formed from the profile of fig. 8 (c) is used and the temperature control (non-control) is not performed on the bending die B and the temperature control (controlled) is performed on the bending die B.

Detailed Description

Hereinafter, a bending die and a method of manufacturing the bending die according to the present invention will be described with reference to the drawings.

Fig. 1 and 2 are conceptual perspective views each showing an embodiment of a bending die (unit bending die) according to the present invention. In the example of the present embodiment, the "bending die" is formed by connecting a plurality of "unit bending dies". Fig. 1 shows an example of a unit bending die disposed at the end of the bending die, and fig. 2 shows an example of a unit bending die disposed adjacent to the unit bending die of fig. 1.

In the present specification, in order to avoid complexity, the same reference numerals are given to corresponding members in different examples of the embodiment.

The unit bending die 1 of fig. 1 includes: a pipe fitting portion 2 that forms a recess for fitting a pipe; a mounting portion 3 for fixing the unit bending die 1 to a frame, not shown; and a connection portion 4 for connecting the unit bending die 1 to an adjacent unit bending die (for example, the unit bending die of fig. 2).

The tube fitting portion 2 is formed with a tube fitting recess 2 a. The recess 2a preferably has a cross-sectional shape that is substantially the same everywhere so that a pipe, not shown, having a substantially the same cross-sectional shape everywhere can be fitted therein. Therefore, the sectional shape of the unit bending die 1 perpendicular to the longitudinal direction (particularly, the sectional shape of the fitting recess 2 a) is always substantially the same. That is, the sections 5a, 5b, 5c, 5d, 5e at different positions of the unit bending die 1 of fig. 1 and the sections 5f, 5g, 5h, 5i, 5j at different positions of the unit bending die 1 of fig. 2 have substantially the same sectional shape. However, since the mounting portion 3 and the connection portion 4 have an auxiliary structure in addition to the fitting recess 2a, the cross-sectional shape of the portion is different from the cross-sectional shape of the other portions.

The shape of the unit bending die 1, 1 illustrated in fig. 1 and 2 is a shape generated by continuously moving the outline 5 including the 1 st closed curve C1 having a substantially circular shape with a concave portion in a three-dimensional space as shown in fig. 3. In this specification, a two-dimensional figure that generates the cross-sectional shape of the bending die (or unit bending die) 1 is referred to as an "outline". Further, a cross section where the contour of the bending die (or the unit bending die) appears is referred to as a "contour surface".

As illustrated in fig. 3, the outline 5 is a planar shape including a1 st closed curve C1 having a substantially circular shape with a concave portion. The profile 5 of fig. 3 comprises: a recess 6; an opening 7; upper surface rail portions 8, 8 which are gentle curves or straight lines adjacent to both sides of the opening 7; the inner part 9 of the opening 7; and lower surface rail portions 10, 10 which are gently curved or straight lines adjacent to both sides of the back side portion 9. The groove width a of the recess 6 is preferably designed to be slightly wider than the opening width b of the recess 6. This is to prevent the tube once fitted into the tube fitting portion 2 formed by the recess 6 from easily falling off.

For the following description to be easily understood, two orthogonal directions are set in the plane 11 containing the outline 5. As shown in fig. 3, for example, the direction of the symmetry axis of the 1 st closed curve C1 of the outline 5 is defined as the y direction, and the direction perpendicular to the y direction is defined as the x direction. The z direction is a direction perpendicular to the x direction and the y direction. In general, the bending die or the unit bending die 1 of the present invention has a shape generated by virtual continuous movement in a three-dimensional space as one outline of a two-dimensional pattern. Representative examples of the continuous movement of the contour in the three-dimensional space are a parallel movement, a gyrating or tilting motion in which a change in the direction of the contour surface is combined with a parallel movement, a twisting motion in which an in-plane rotation of the contour surface is combined with a parallel movement, or a motion in which these are combined. In addition, when viewed from an externally fixed three-dimensional space, the y-direction and the x-direction within the outline 5 appear to change as the outline moves. Of course, the z-direction, which is perpendicular to the x-direction and the y-direction, also appears to vary.

The parallel movement of the contour in the three-dimensional space means that the surface 11 including the contour 5 is simply moved in the z direction. The circling motion Ry is a motion in which the direction of the surface 11 of the outline is rotated about the direction (y direction) of the opening 7 of the outline 5, or the rotation and the parallel movement are combined. The tilt movement Rx is a movement in which the direction of the surface 11 of the outline is rotated about the direction (x direction) perpendicular to the direction of the opening 7 of the outline 5, or the rotation and the parallel movement are combined. The in-plane rotation Rz of the contour surface means that the contour is rotated about the direction (x direction) perpendicular to the direction of the opening 7 of the contour 5 without changing the direction of the contour surface 11, and the twisting motion means a motion combining the in-plane rotation Rz and the parallel translation.

The movement of the contour in the present invention is not limited to these movements, and may be a continuous and smooth movement in one direction without changing the shape of the contour 5. For example, a combination of the above-described motions is also included.

For example, the section from the left end profile surface 5a to the next profile surface 5b in fig. 1 is a parallel motion, the section to the next profile surface 5c is an inclination motion with the x direction as the axis, the section to the vicinity of the next profile surface 5d is a parallel motion, the section to the right end profile surface 5e is a motion of a profile in which the inclination motion and the parallel motion are combined, and the unit bending die 1 has a shape generated by these profile motions.

In addition, the section from the left end profile 5f to the next profile 5g in fig. 2 is a parallel translation, the section to the next profile 5h is a motion in which a tilt motion, a swivel motion, and a torsion motion are combined, the section to the next profile 5i is a torsion motion, and the section to the right end profile 5j is a parallel translation, and the unit bending die 1 has a shape generated by these profile motions.

These movements are movements that are made imaginarily in the design of the bending die. The shape of the bending die is determined based on the virtual motion, and a design drawing, numerical data relating to the shape, and the like are created. Based on the design drawing and data, a bending die or a unit bending die is produced by a three-dimensional printing technique using metal (e.g., aluminum, stainless steel) or heat-resistant resin as a material. Techniques for three-dimensional printing of metals and other materials are known per se, and therefore, a detailed description thereof is omitted here.

Since the pipe fitting portion 2, the mounting portion 3, the connecting portion 4, and the like shown in fig. 1 and 2 are formed by three-dimensional printing, the members attached to the unit bending die 1 may be integrally formed for each unit bending die.

The unit bending die 1 of fig. 1 and the unit bending die 1 of fig. 2 are joined at the contour surface 5e of fig. 1 and the contour surface 5f of fig. 2. In order to connect the unit bending dies 1 and 1, connection portions 4 and 4 are provided at the right end of the unit bending die of fig. 1 and the left end of the unit bending die of fig. 2, respectively.

Fig. 4 is a conceptual perspective view of the unit bending dies 1 and 1 of fig. 1 and 2 when they are connected. As shown in fig. 4, the connecting portion 4 is formed integrally with the unit bending die 1 as a substantially rectangular parallelepiped portion below the end portion of each unit bending die 1. Each of the connecting portions 4 has a hole 4a for inserting a screw. The two unit bending dies 1, 1 can be connected by bringing the contour surface 5e of fig. 1 into contact with the contour surface 5f of fig. 2, inserting a screw 12a through each of the holes 4a, and fastening and fixing the screw by a nut 12b, as shown in fig. 4. By repeating this process, a long bending die can be formed. In the case where the size of the product is not long, a single unit bending die is sufficient, and therefore, the connection portion is not required.

The pipe may be heated in advance when the thermoplastic resin pipe is fitted into the bending die 1, or the pipe may be cooled in order to quickly take out the molded product from the bending die 1. Even if the tube is intentionally preheated, the temperature of the tube decreases when the temperature of the bending die 1 is low. As a result, the molding may not be performed as intended. Even if the product is to be cooled quickly, a long time may be required for cooling when the temperature of the bending die 1 is high. In order to avoid such a problem, it is preferable to be able to control the temperature of the bending die 1.

In the bending die 1 of the present invention, a heat medium hole 13 through which a temperature control medium (liquid or gas) for heating or cooling the bending die flows can be provided inside the bending die. Fig. 5 (a) is a front view of an example of the outline in the case where one hole for a heat medium is formed. The 2 nd closed curve C2 formed by closed curves is included inside the contour 5 including the 1 st closed curve C1. By continuously moving the 1 st closed curve C1 and the 2 nd closed curve C2 in the three-dimensional space, the bending die 1 in which the holes 13 for the heat medium are formed can be realized. Fig. 5 (B) shows an example of the outline 5 including two 2 nd closed curves C2 and C2 for forming two holes for heat medium. In fig. 5 (a), the same reference numerals are given to the same portions or regions as the outline of fig. 3.

Fig. 6 is a conceptual perspective view showing, in a cutaway manner, the bending die 1 generated by continuously moving the contour 5 of fig. 5 (a) in a three-dimensional space. The region surrounded by the 2 nd closed curve C2 is a cavity, and the heat medium hole 13 is formed.

Since the heat medium hole 13 does not function unless it is connected to the adjacent bending dies 1 and 1, the heat medium hole 13 is also formed in the connecting portion 4. As shown in fig. 1 and 2, the hole 13 for the heat medium of the bending die 1 continuously transitions to the hole 13a for the heat medium formed inside the connection portion 4, and the hole 13a for the heat medium is formed so that when the unit bending die 1 of fig. 1 is brought into contact with the unit bending die 1 of fig. 2, the pipe fitting portions 2, 2 communicate with each other and the opening portions 13b, 13b of the holes 13, 13 for the heat medium communicate with each other.

An O-ring seat 13c is provided in an opening 13b of the heat medium hole 13 in the connection portion of the bending die 1 in fig. 1. As shown in fig. 4, the O-ring 13d is fitted into the O-ring seat 13c, the opening 13b of the connecting portion 4 of the bending die 1 shown in fig. 2 is brought into contact therewith, the screw 12a is inserted through the holes 4a and 4a, and the two adjacent bending dies 1 and 1 are fastened and fixed by the nut 12b, whereby the heat medium holes 13 and 13 can be connected without fluid leakage. By repeating this process, the temperature of the bending die can be controlled by flowing the heat medium through all the unit bending dies.

A supply/discharge port 14 for supplying or discharging the heat medium to or from the heat medium hole 13 is formed in the unit bending die positioned at both ends of the series of unit bending dies forming the bending die. Fig. 1 shows an example of the supply/discharge hole 14. The unit bending die 1 is provided with a mounting portion 3, the mounting portion 3 is provided with a hole 13a for a heat medium, and an end of the hole 13a for the heat medium is connected to a supply/discharge port 14.

The series of unit bending dies connected in series by the connection portion 4 are fixed to a frame, not shown, that supports the apparatus at all or a part of the position of the connection portion 4 or the position of the mounting portion 3. The mounting is appropriately fixed to a housing, not shown, by screws, clamps, or welding according to the situation of the site.

Fig. 7 is a conceptual perspective view of a bending die 1 formed by connecting a plurality of unit bending dies 1, 1 · · and freely bending in a three-dimensional space. In fig. 7, a connecting portion for connecting adjacent unit bending dies, a mounting portion for fixing the unit bending dies to the housing, and the like are omitted. When the bending die 1 is formed in this manner, the bending die 1 can be formed into a shape in which the pipe fitting portion 2 is freely rotated, a shape in which it is lifted and lowered, or a spiral shape. In this case, unlike the conventional art, the tube fitting portion 2 is not limited to be opened in a specific direction in a three-dimensional space (for example, a z-axis direction of an xyz orthogonal axis). This has the following advantages.

When the thermoplastic resin pipe is fitted into the bent portion of the pipe fitting portion 2, the pipe may be flattened or buckled. This phenomenon often occurs when there is no y-direction (referred to as "opening direction") of the profile surface of the tube insertion portion in a plane (referred to as "bending plane") including the center line of the tube insertion portion on both sides of the bent portion of the bending die. On the other hand, when the angle (referred to as "insertion angle") formed by the bending plane and the opening direction is 0 ° or 180 °, this phenomenon does not occur so much.

In the case where a product having a complicated shape as illustrated in fig. 7 is produced by fitting a thermoplastic resin tube into the bending die 1 of the present invention, since there is a degree of freedom in design with respect to the position at which the tube fitting portion 2 is provided in the bending die 1, the deviation of the "insertion angle" from 0 ° or 180 ° can be reduced by optimally designing the relationship between the "bending plane" and the "opening direction" at each portion of the tube fitting portion 2. As a result, the occurrence of a phenomenon in which the tube "becomes flat or buckles" during the insertion process can be reduced as much as possible.

In addition, the bending die 1 of the present invention has an effect that a self-propelled pipe inserting apparatus can be used. To explain this, first, the correspondence between the contour 5 and the shape of the bending die or the unit bending die 1 will be explained. The recess 6 and the opening 7 forming the 1 st closed curve C1 of the profile 5 of fig. 3 of the bending die 1 correspond to the tube insert 2 of fig. 7. The gently curved or straight upper surface rail portions 8, 8 adjacent to both sides of the opening 7 of fig. 3 correspond to the pair of upper surface rails 17, 17 of fig. 7. The connecting portion 4 and the mounting portion 3 of the unit bending die 1 illustrated in fig. 1 and 2 are formed at positions corresponding to the back side portion 9 of the opening 7 of fig. 3. The lower surface rail portions 10, which are gently curved or straight lines adjacent to both sides of the back side portion 9 in fig. 3, correspond to the pair of lower surface rails 18, 18 in fig. 7.

The shape formed by the movement of the outline 5 in the three-dimensional space in fig. 3 is such that, as illustrated in fig. 7, a pair of upper surface rails 17, 17 and a pair of lower surface rails 18, 18 extending along the pipe fitting portion 2 are provided around the bending die 1. This means that after the tube is temporarily placed in the tube insertion portion 2, a member such as a hand or a slider (japanese fold) is slid along the upper surface rails 17, 17 and the lower surface rails 18, so that the tube can be reliably inserted into the tube insertion portion 2 with ease.

Instead of hands or sliders, sliders that self-travel along these upper surface rails 17, 17 and lower surface rails 18, 18 can also be employed. For example, by providing sliders that slide on the upper surface rails 17, 17 and rollers that roll on the lower surface rails 18, and rotating the rollers while sandwiching the bending die 1 therebetween, the movable body into which the pipe is inserted is made to self-travel, and the pipe can be inserted without using a human hand.

Next, the shape of the 2 nd closed curve C2 for forming the heat medium hole 13 for temperature management of the bending die 1 will be described. The 2 nd closed curve C2 composed of closed curves inside the 1 st closed curve C1 having the outline 5 forms the hole 13 for heat medium as described above. Further, since the heat medium is used to control the temperature of the bending die 1 and the pipe to be fitted, it is preferable to form the heat medium hole 13 having high heat exchange efficiency. Therefore, wrinkles are formed on the inner surface of the hole to increase the surface area of the heat medium hole 13. That is, the 2 nd closed curve C2 may be provided with a concave-convex shape to extend the line.

Fig. 8 is a front view showing some preferred examples of the shape of the outline, particularly the shape of the 2 nd closed curve C2. Fig. 8 (a) shows a case where the profile 5 does not have the 2 nd closed curve C2 but is constituted only by the 1 st closed curve C1, and the bending die has a solid structure. (b) To (f) are cases having the 2 nd closed curve C2, and the bending die is of a hollow structure, and the hollow is used as the hole 13 for heat medium. (b) The case where the protrusion is formed on the inner surface of the hollow portion is shown, (C) the case where the hollow portion is divided into two including two 2 nd closed curves, (d) the case where the protrusion having a circular cross section is formed on the inner surface of the hollow portion, (e) the case where the protrusion having a triangular cross section is formed on the inner surface of the hollow portion, and (f) the case where the 2 nd closed curve C2 is formed of a plurality of closed curves and the hollow portion is formed of a plurality of bundles of thin tubes.

Fig. 9 is a graph showing measurement examples of three-point temperature changes in the case where a thermoplastic resin pipe is formed using a solid bending die a formed from the profile of fig. 8 (a) and in the case where a pipe is formed using a bending die B having two holes for a heat medium formed from the profile of fig. 8 (c) (time (sec) on the horizontal axis and temperature (deg.c) on the vertical axis).

In this measurement, neither the bending die a nor the bending die B was heated or cooled, and the temperature was controlled by feeding a heat medium into the tube. Fig. 10 shows temperature measurement points a1, a2, and A3 (measurement points of bending die a) and temperature measurement points B1, B2, and B3 (measurement points of bending die B) in each bending die A, B. Reference numerals marked on the temperature change curve of fig. 9 indicate changes in temperature at the respective measurement points of the respective bending dies. The tube is inserted into the bending die at time S of fig. 9. The ambient temperature was 26. + -. 2 ℃.

The following can be understood from fig. 9.

1) Immediately after the insertion, the temperatures a2 and B2 at the center of the lower surface of the tube both decreased instantaneously and increased gradually.

2) Until the tube is heated, the temperature difference (A3-A2) between the upper surface and the lower surface of the tube in any bending die A, B and (B3-B2) are 40 ℃ or more, which affects the shape stability of the tube.

3) After the tube was inserted into the bending die, the temperature increase rate of B2 of the lower surface of the tube was 4 times that of a 2.

As a result, it is found that the hollow bending die B has a faster temperature response than the solid bending die a even without temperature control of the bending die.

This measurement example shows that when a thermoplastic resin pipe is molded using the bending die of the present invention, particularly when a hollow bending die is used, an effect of improving the temperature responsiveness can be obtained.

Fig. 11 is a view showing an example of measurement of temperature changes at three points shown in fig. 10 of a pipe in the case where the bending die B having 2 holes for a heat medium formed from the profile of fig. 8 (c) is used and the temperature control (non-control) is not performed on the bending die B and the temperature control (controlled) is performed on the bending die B. When the temperature control (non-control) is not performed, the bending die B is not heated or cooled. On the other hand, in the case of performing the temperature control (controlled), the following temperature control is performed: in the bending step, the bending die and the pipe are heated simultaneously by feeding a heat medium into the bending die and the pipe, and when the temperature reaches a set temperature, the heating of the bending die is stopped before the pipe is heated, and after the heating of the pipe is completed, the bending die and the pipe are cooled simultaneously. Then, in this measurement, the temperature changes in the respective cases are compared.

The temperature measurement points B1, B2, and B3 are three points shown in fig. 10. Reference numerals B1non, B2non, and B3non indicated on the temperature change curve of fig. 11 indicate temperature changes at the respective points described above in the case where temperature control is not performed, and reference numerals B1con, B2con, and B3con indicate temperature changes at the respective points described above in the case where temperature control is performed. The tube is inserted into the bending die at time S of fig. 11. The transition temperature T shown by a thin broken line in fig. 11 is the glass transition point of the thermoplastic resin, and the product can be taken out when the temperature falls below the transition temperature T. The ambient temperature was 26. + -. 2 ℃.

The following can be understood from fig. 11.

1) When the tube is inserted into the bending die and the tube is in contact with the preheated bending die, the temperature change of B2con is smaller than that of B2 non.

2) The temperature difference (B2 con-B3 con) is smaller than the temperature difference (B2 non-B3 non) until the tube heating is completed after the tube is inserted, and the tube shape is stable.

3) When the tube is cooled, the temperatures B2con and B3con of the entire tube at the time of temperature control (controlled) are 1.5 times the temperatures B2non and B3non of the entire tube at the time of non-temperature control (non-controlled) and the glass transition temperature (T46 ℃) of the material or less. This measurement example shows that, when a thermoplastic resin pipe is molded using the bending die provided with the holes for a heat medium of the present invention, when the temperature of the bending die is controlled, the pipe can be molded while maintaining the condition that the temperature of the pipe is uniform, and therefore, an effect is obtained that unexpected deformation of the pipe can be prevented and the cooling time after molding can be shortened.

The temperature change at each point described above naturally varies depending on the type, temperature, flow rate, and other conditions of the heat medium to be fed into the tube and the heat medium to be fed into the heat medium hole of the bending die for tube temperature control, but the above-described effects can be obtained in any case.

The bending die and the method for manufacturing the bending die for bending, fitting, heating and cooling a pipe to be molded according to the present invention have been described in detail above, but it is needless to say that the object to which the present invention is applied is not limited to the example illustrated in the drawings, and can be implemented as an apparatus and a method according to other embodiments under the same technical idea.

Industrial applicability

According to the bending die of the present invention, even if the shape of a product manufactured by fitting a thermoplastic resin tube into the bending die exceeds 2 m, and even if the product has a complicated shape which can be freely bent in a three-dimensional space, the bending die can be manufactured, and therefore, the bending die can be widely used for bending various resin-made or metal-made pipes and hoses which are used particularly as parts of automobiles.

Description of the reference numerals

1 bending die, Unit bending die

2 pipe insert

2a fitting recess

3 mounting part

4 connecting part

5 profile

5 a-5 j profile surface

6 concave part

7 opening

8 upper surface track part

9 inner side part of opening

10 lower surface track part

11 plane containing the contour

12a screw

12b nut

13. 13a hole for heat medium

13b opening part

13d O shaped ring

14 supply/discharge hole

17 upper surface track

18 lower surface rail

C1 closed curve 1

C2 closed curve 2

20 tubes.