JP7493200B2 - In-plane bending method and in-plane bending device - Google Patents

Description

The present invention relates to an in-plane bending method and an in-plane bending device for bending strip-shaped plate material in-plane.

As a processing method for edgewise bending, which bends a strip-shaped plate material in-plane, a manufacturing method for an aluminum alloy bus bar shown in Patent Document 1 is known, for example. The invention of Patent Document 1 aims to prevent the occurrence of cracks (fissures) and thickness variations (necking) in the outer periphery of the bent part. In the manufacturing method of Patent Document 1, the thickness of both end edges in the plate width direction of the part to be bent before processing is changed by coining, thereby improving the workability of the bent part and suppressing the occurrence of defects such as cracks and thickness variations in the outer periphery.

JP 2019-195827 A

When edgewise bending is performed, a compressive force acts on the inner circumference of the bent portion, which causes the inner circumference 102 of the bent portion 101 of the plate material 100 to buckle, resulting in processing defects, as shown in FIG. 6.

The present invention aims to provide an in-plane bending method and an in-plane bending device that can be used to bend strip-shaped plate material in-plane without causing defects even in the inner periphery of the bent part.

The first invention for solving such problems is an in-plane bending method for bending a strip-shaped plate material in-plane using a wing-type in-plane bending device equipped with a pair of wing-type dies each rotatable about a pair of fulcrums and a punch equipped with a pressing surface of a desired curvature. This in-plane bending method includes a plate material setting step of setting the plate material across the support surfaces of the pair of wing-type dies in a state in which the plate material is sandwiched from both sides in the plate thickness direction via restraint plates, and a bending step of simultaneously pressing the punch against the plate material and the restraint plates so as to push open the pair of wing-type dies, characterized in that in the plate material setting step, the restraint plates are arranged so as to cover the entire side surface of at least the bent portion of the plate material in a state before the bending step is performed, and in the bending step, the restraint plates are inclined together with the wing-type dies .

According to the in-plane bending method of the present invention, the entire side of the bent portion of the plate is covered via the restraining plate, and the plate is bent while being sandwiched near the bend line. This prevents buckling at the inner periphery of the bent portion and suppresses the occurrence of processing defects. As the bending process progresses, the central portion of the plate is exposed from the restraining plate, but the exposed portion is where the bending process is complete, and although there is some propagation of the bending moment, buckling such as wrinkles is unlikely to occur. In addition, the bending state of the plate is close to four-point bending with a punch and wing-type die, so local processing defects are unlikely to occur.

The second invention for solving the above problem is an in-plane bending device for bending a strip-shaped plate material in-plane. The in-plane bending device includes a pair of wing-type dies each rotatable about a pair of fulcrums and having a support surface for the plate material, a punch having a pressing surface with a desired curvature, and a restraining plate provided on each of the pair of wing-type dies and fixed to the wing-type dies while sandwiching the plate material from both sides in the plate thickness direction. The restraining plate covers at least the entire side surface of the bent portion of the plate material before bending, is pressed by the punch simultaneously with the plate material, and inclines together with the wing-type dies .

The in-plane bending device of the present invention can perform bending while covering and clamping the entire side of the bent portion of the plate material, so buckling does not occur at the inner circumference of the bent portion and no processing defects occur. As the bending process progresses, the center of the bent plate becomes exposed from the restraining plate, but the exposed part is where the bending process is complete, and although there is some propagation of the bending moment, buckling such as wrinkles is unlikely to occur. In addition, the bending state of the plate material is close to four-point bending with a punch and wing-type die, so local processing defects are unlikely to occur.

In the in-plane bending device of the present invention, it is preferable that the restraining plates are arranged on both sides of the plate material. In this case, the separation distance between the restraining plates is greater than the thickness dimension of the plate material by a predetermined clearance, and the clearance is preferably large enough to allow the plate material to be fitted between the restraining plates and to receive a reaction force from the restraining plates without causing any further increase in thickness within the clearance when the plate material increases in thickness due to bending. With this configuration, the plate material can be restrained from both sides, making it easy to clamp the plate material. In addition, by changing the thickness of the restraining plates, it is possible to accommodate plate materials of various thicknesses.

In addition, in the in-plane bending device of the present invention, it is preferable that the support surface of the wing die for the plate material is located below the fulcrum. With this configuration, the frictional force between the plate material and the wing die acts on the axial tension side at the inner periphery of the bending section, which is advantageous against buckling.

According to the present invention, when bending a strip-shaped plate material in-plane, it is possible to suppress the occurrence of processing defects not only on the outer periphery but also on the inner periphery of the bent portion.

FIG. 2 is a cross-sectional view showing a state before bending of the in-plane bending apparatus according to the embodiment of the present invention. 4 is a cross-sectional view showing a state after bending of the in-plane bending apparatus according to the embodiment of the present invention. FIG. 1 is a perspective view showing an in-plane bending apparatus according to an embodiment of the present invention; 1 is an exploded perspective view showing an in-plane bending apparatus according to an embodiment of the present invention; 1A to 1C are cross-sectional views showing bending steps of an in-plane bending method according to an embodiment of the present invention. FIG. 1 is a perspective view showing a plate material bent by a conventional in-plane bending method.

The in-plane bending method and in-plane bending device according to an embodiment of the present invention will be described in detail with reference to the drawings. The in-plane bending method is a method of bending a strip-shaped plate material 2 in-plane (edgewise bending) using an in-plane bending device 1 shown in Figures 1 to 4. In this embodiment, the plate material 2 is made of an aluminum alloy. The in-plane bending method and in-plane bending device 1 of the present invention are used to form bus bars from an aluminum alloy, for example, for use in automobiles, etc.

First, the configuration of the in-plane bending device 1 will be described. The in-plane bending device 1 according to this embodiment includes a pair of wing-type dies 10, 10 that can rotate around a pair of support shafts (supports) 11, 11, a punch 50 with a pressing surface 51 of a desired curvature, and a restraining plate 12 that restrains the plate material 2 from both sides in the plate thickness direction. The plate material 2 is arranged on the wing-type die 10 so that its length extends horizontally and its plate width direction is vertical. In this embodiment, the horizontal direction when the in-plane bending device 1 is viewed from the side (as shown in Figures 1 and 2) is the left-right direction, the vertical direction is the up-down direction, and the front-back direction of the paper is the front-back direction (front side is front, back side is back).

The left and right wing-type dies 10, 10 are symmetrical with respect to the center line CL in the left-right direction of the in-plane bending device 1. The wing-type die 10 includes a base portion 13 and a rising portion 14. The base portion 13 is a plate-shaped portion extending along the left-right direction. On the upper surface of the base portion 13, a support surface 15 and a mounting surface 16 are arranged from the center line CL side toward the outside. The support surface 15 is a surface that supports the plate material 2 and is provided in the center of the width direction (front-rear direction) of the base portion 13. The support surface 15 is formed with a predetermined length from the end on the center line CL side toward the outer end. The mounting surface 16 is a surface on which a chuck 17 (shown only in FIG. 1) that fixes the end of the plate material 2 is placed, and is one step lower than the support surface 15 (see FIG. 1). The mounting surface 16 is formed with a predetermined length from the outer end position of the support surface 15 toward the outer end.

The rising portion 14 is provided in a pair with a gap in the front-rear direction. The pair of front and rear rising portions 14, 14 rise up so as to surround the support surface 15 from both sides at both ends of the width direction (front-rear direction) of the base portion 13. The rising portion 14 is provided with a pressed surface portion 18 and a bearing portion 19. The pressed surface portion 18 is a portion pressed by the punch 50 from above, and its upper end surface becomes the pressed surface 18a. The pressed surface 18a extends a predetermined length from the end on the center line CL side toward the outer end. The extension length (left-right length) of the pressed surface 18a is shorter than the extension length (left-right length) of the support surface 15. The height dimension of the pressed surface portion 18 is equal to the width dimension of the plate material 2 (the height dimension when installed on the wing-type die 10). The pressed surface 18a is hardened.

The bearing portion 19 is a portion that supports the wing-type die 10 rotatably with the support shaft 11 as a fulcrum, and is formed with a predetermined length from the outer end position of the pressed surface portion 18 toward the outer end. The outer end of the bearing portion 19 is at the same position as the outer end of the support surface 15. The side of the bearing portion 19 is flush with the side of the pressed surface portion 18. The upper end of the bearing portion 19 protrudes above the pressed surface 18a. The bearing portion 19 has a through hole 20 through which the support shaft 11 passes. The through hole 20 is formed above the support surface 15, and the wing-type die 10 of this embodiment is an upper fulcrum type.

The wing-type die 10 is supported by a support member 25. As shown in FIG. 3 and FIG. 4, a pair of support members 25 are provided at an interval in the front-rear direction and are arranged to surround the wing-type die 10 from both sides in the front-rear direction. The support member 25 has a pair of left and right support parts 26, 26 and a connecting part 27 connecting them. The support part 26 is made of a plate-like member extending upward. At the upper end of the support part 26, a through hole 28 through which the support shaft 11 passes is formed. The through hole 28 has the same diameter as the through hole 20 of the wing-type die 10, and the through hole 28 and the through hole 20 are arranged coaxially. The support shaft 11 is composed of a pin and is inserted from the through hole 28 side of the support member 25 toward the through hole 20 of the wing-type die 10. The length of the pin shaft is the combined length of the thickness of the support member 25 and the thickness of the rising portion 14 of the wing-type die 10, and the tip surface of the pin is flush with the side surface of the rising portion 14. The connecting portion 27 is continuous with the lower ends of the support portions 26, 26 and extends in the left-right direction. The connecting portion 27 and the support portions 26, 26 are integrated. A screw hole (not shown) is formed in the connecting portion 27. The support member 25 is screwed to the base 30 through this screw hole.

The base 30 is a plate-like member that connects the pair of support members 25, 25, and is provided at the bottom of the support members 25, 25. A convex portion 31 that protrudes upward is formed in the middle of the width direction (front-rear direction) of the base 30. The width dimension (front-rear dimension) of the convex portion 31 is equal to the distance between the support members 25, 25. The front and rear side surfaces of the convex portion 31 serve as positioning guides for the support members 25, 25. A through hole 32 is formed in the middle of the left-right direction of the convex portion 31. A die cushion 33 that supports the wing-type die 10 from below is inserted into the through hole 32. The die cushion 33 is provided so that it can be raised and lowered, and when the wing-type die 10 is pressed by the punch 50, it descends together with the wing-type die 10, applying a reaction force to the wing-type die 10 at this time.

The restraining plate 12 is a member that restrains the side of the plate material 2 from the out-of-plane direction. Two restraining plates 12 are provided in each wing-type die 10, and are arranged on both the front and rear sides of the plate material 2. The restraining plates 12, 12 are made of rectangular plate material of the same shape, and are inserted between the support members 25, 25 of the wing-type die 10. The restraining plate 12 is arranged along the support surface 15, and is screwed in a state of abutting against the side of the rising portion 14. The two restraining plates 12, 12 are arranged with a gap between them. The distance between the restraining plates 12, 12 is larger than the thickness of the plate material 2 by a predetermined clearance. Specifically, the thickness of the restraining plate 12 is set so that there is an appropriate clearance between the restraining plate 12 and the plate material 2. The clearance is set to a size that allows the plate material 2 to be fitted between the restraining plates 12, 12, and that receives an appropriate reaction force from the restraining plates 12 without any further increase in thickness within the clearance when the plate material 2 is increased in thickness by bending. As an example, when the thickness of the plate material 2 is about 2 mm, the total of the clearances on both sides of the plate material 2 is preferably about 0.2 mm. In other words, the separation dimension of the restraining plates 12, 12 is about 110% of the plate thickness dimension of the plate material 2. As a result, the plate material 2 is sandwiched between the two restraining plates 12, 12 between the rising parts 14, 14.

The height dimension of the restraining plate 12 is equal to the width dimension of the plate material 2 (the height dimension when installed in the wing-type die 10) and the height dimension of the pressed surface portion 18. As a result, when the plate material 2 is installed in the wing-type die 10 while being sandwiched between the restraining plates 12, 12, the upper surface of the pressed surface portion 18 of the rising portion 14 of the wing-type die 10, the upper surface of the restraining plate 12, and the upper surface of the plate material 2 are flush with each other. In other words, immediately before bending, the entire side surface of the bending portion 3 of the plate material 2 (the portion to be bent) is restrained by the restraining plate 12, and the lower surface is restrained by the support surface 15.

The punch 50 is provided above the wing die 10 and on the center line CL of the in-plane bending device 1. The punch 50 descends to press down the center end of the wing die 10, tilting the wing die 10 and bending the plate material 2. The lower end of the punch 50 is formed into a curved surface with a desired curvature, and this curved surface serves as the pressing surface 51. The desired curvature is the radius of the curved surface of the inner periphery of the plate material to be bent. The curved pressing surface 51 is hardened.

Next, we will explain the in-plane bending method using the in-plane bending device 1 configured as described above and the effects of the present invention. This in-plane bending method includes a preparation process, a plate placement process, and a bending process.

The preparation process is a process of installing a restraining plate 12 of a desired thickness on the wing-type die 10. The thickness of the restraining plate 12 is selected so that the thickness of the two restraining plates 12, 12 stacked with the plate material 2 to be processed is equivalent to the distance between the rising portions 14, 14 of the wing-type die 10. In the preparation process, the restraining plate 12 is fixed to the inner side surface of the rising portion 14 with screws or the like.

The plate material installation process is a process of installing the plate material 2 across the support surfaces 15, 15 of a pair of wing-type dies 10, 10. In the plate material installation process, the plate material 2 is fitted between the restraining plates 12, 12 and installed on the support surfaces 15. The plate material 2 is positioned so that the center of the bending portion 3 to be bent is located at the butt joint of the pair of wing-type dies 10, 10. When it is necessary to bend the plate material 2 by applying an axial force, both ends of the plate material 2 can be fixed with chucks 17 (see FIG. 1). At this time, the entire side of the bending portion 3 of the plate material 2 is restrained by the restraining plates 12, 12, and the bottom surface is restrained by the support surfaces 15.

The bending process is a process in which the punch 50 is pressed against the sheet material 2 to bend the sheet material 2 in-plane. In the bending process, the punch 50 is lowered to press the sheet material 2 so as to push the pair of wing-type dies 10, 10 apart. The pressing surface 51 of the punch 50 abuts against the pressed surface portion 18a of the wing-type die 10, the upper surface of the restraining plates 12, 12, and the upper surface of the bent portion 3 of the sheet material 2, and presses downward. As shown in (a) to (c) of FIG. 5, in the bending process, as the punch 50 descends, the end portion of the wing-type die 10, 10 on the center line CL side is pressed down, and the wing-type die 10, 10 is inclined. At this time, the reaction force that the sheet material 2 receives from the support surface 15 always acts on the undeformed portion of the sheet material 2 in a surface, so that the fulcrum reaction force acting from the die (fulcrum) as seen in three-point bending does not locally make an indentation on the undeformed portion. Furthermore, the vicinity of the bending line of the bent portion 3 can be constantly pressed against the pressing surface 51 of the punch 50. Therefore, the plate material 2 can be well fitted to the punch 50. The punch 50 descends to the bottom dead center, and when press bending is completed, it rises and returns to its original position. The wing-type die 10 is returned to its original horizontal position by the rise of the die cushion 33.

In the case of a wing-type in-plane bending device, the processing limit is when the inner periphery (upper edge) of the bending portion 3 bends the central part of the workpiece at the initial stage of processing and separates from the punch, or when periodic undulating "wrinkles" occur on the compression side (inner periphery) of the bending, and out-of-plane deformation called "lateral buckling" occurs in which the cross section falls out of the bending plane. In the in-plane bending method and in-plane bending device 1 of this embodiment, the plate material 2 is sandwiched between the restraining plates 12, 12 to suppress out-of-plane deformation of the bending portion 3. In particular, the restraining plates 12, 12 sandwich the area from the bending line of the plate material 2 to the outer end in the plate thickness direction, and further, when the plate material 2 increases in thickness at the inner periphery of the bending portion 3 and comes into close contact with the restraining plates 12, the plate material 2 receives an appropriate force from the restraining plates 12, 12, so that buckling can be suppressed. Therefore, the out-of-plane deformation of the bending portion 3 can be further suppressed.

In addition, as shown in (b) and (c) of Figure 5, when the wing-type die 10 is tilted, the plate material 2 is bent in a state where it is supported at almost four points by the punch 50 and the wing-type die 10, so although the bending moment is transmitted to the central part of the bent portion 3 where bending has already been completed, no local deformation occurs. Therefore, processing defects are less likely to occur in the middle part of the bent portion 3.

When the wing-type die 10 is tilted, the central bent portion of the plate material 2 is exposed from the restraining plates 12, 12. However, what is exposed from the restraining plates 12, 12 is the processed portion where bending has been completed, and the portion undergoing plastic deformation is sandwiched between the restraining plates 12, 12, so out-of-plane deformation such as "wrinkles" can be suppressed.

Furthermore, since the wing-type die 10 of this embodiment is an upper support type in which the through hole 20 through which the support shaft 11 passes is formed above the support surface 15, if the end of the sheet material 2 is restrained by the chuck 17, a tensile force on the axis acts on the sheet material 2 from the early stage of bending deformation, and increases as bending progresses. This reduces the compressive stress, which is advantageous against buckling. Therefore, the out-of-plane deformation of the sheet material 2 can be further suppressed.
On the other hand, if the plate material is more prone to cracking on the tension side than buckling on the compression side, a method can be used in which the wing die is, for example, a bottom support type rather than an upper support type, to reduce the tensile stress generated in the plate material.

Although the embodiment for implementing the present invention has been described above, the present invention is not limited to the above embodiment, and appropriate design changes are possible within the scope of the present invention. For example, in the above embodiment, the plate material 2 is sandwiched between two restraining plates 12, 12, but this is not limited to this. The plate material may be sandwiched between one restraining plate and the side of the rising portion of the wing-type die. Also, a method of pressing the restraining plate against the plate material by load control may be used.

In addition, in the above embodiment, the plate material 2 made of an aluminum alloy is bent, but the material of the plate material 2 is not limited to an aluminum alloy. The in-plane bending method and in-plane bending device 1 can also process plate materials made of other metals.

Reference Signs List 1 In-plane bending device 2 Plate material 3 Bending section 10 Wing-type die 11 Support shaft (support point)
12 Restraint plate 15 Support surface 50 Punch 51 Pressing surface

Claims (4)

An in-plane bending method for in-plane bending a strip-shaped plate material using a wing-type in-plane bending device including a pair of wing-type dies each rotatable about a pair of fulcrums and a punch having a pressing surface with a desired curvature, comprising:
a plate material installation process in which the plate material is placed across the support surfaces of the pair of wing-type dies in a state in which the plate material is sandwiched from both sides in the plate thickness direction via restraint plates;
and a bending process of simultaneously pressing the punch against the plate material and the restraining plate so as to push open the pair of wing-type dies,
In the plate material setting step, the restraint plate is disposed so as to cover at least the entire side surface of the bent portion of the plate material in a state before the bending step is performed ;
In the bending process, the restraining plate is inclined together with the wing-type die.
The in-plane bending method is characterized by the above. In an in-plane bending apparatus for bending a strip-shaped plate material in-plane,
A pair of wing-type dies each rotatable about a pair of fulcrums and having a support surface for the plate material;
A punch having a pressing surface with a desired curvature;
A pair of restraining plates are provided on each of the pair of wing-type dies and fix the plate material to the wing-type dies while sandwiching the plate material from both sides in the plate thickness direction,
The restraining plate covers at least the entire side surface of the bent portion of the plate material before bending , and is pressed by the punch simultaneously with the plate material and inclined together with the wing-type die.
An in-plane bending apparatus characterized by the above. The restraining plates are disposed on both sides of the plate material,
The spacing between the restraining plates arranged on both sides is greater than the thickness of the plate material by a predetermined clearance,
The in-plane bending apparatus according to claim 2, characterized in that the clearance is large enough to fit the plate material between the restraint plates and to receive a reaction force from the restraint plates without causing any further increase in thickness within the clearance when the plate material increases in thickness due to bending. The in-plane bending apparatus according to claim 2 or 3, wherein the support surface of the wing-type die is located below the fulcrum.

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