JP4461843B2 - Processing method of metal plate with less springback - Google Patents

Description

  The present invention relates to a method of pressing a metal plate with less spring back.

  In recent years, in order to reduce the weight of automobile bodies, high-tensile steel plates or aluminum alloy plates with a low specific gravity have been used. These metal plates are formed into a molded body by press working using a mold in which ordinary punches and dies are arranged to face each other. At that time, high-strength steel plates and aluminum alloy plates have higher strength or lower Young's modulus than ordinary steel, so the spring back of the compact is large and it is difficult to obtain a compact with a predetermined shape by pressing. It is.

  Taking the example of the hat-shaped molded body 10 as an example, the spring back will be described with reference to FIGS. 7.a to 7.c. When the shape as shown in FIG. Changing to a shape like 7.c is called springback.

  As shown in FIGS. 8.a to 8.c, the conventional press working method is performed by sandwiching a metal plate material 11 between a die 12 and a wrinkle retainer 14 and inserting a punch 13 into the die 12. A metal material was passed along the die shoulder 12a, and the standing wall 1 was formed by drawing. The upright wall 1 is a portion that is bent by the die shoulder 12a in the drawing process and then bent back to a flat amount and has a large total deformation amount.

  Further, a press working method for forming the standing wall 1 by simple press bending as shown in FIGS. 9.a to 9.d is often used. Although this method using the die 22 and the punch 23 has an advantage that the apparatus is simple, the standing wall 1 has a metal plate material 21 wound around the die shoulder 22a in the process of simple press bending as in the case of drawing. It is bent by the shoulder 22a and then bent back flat. For this reason, the conventional press working method has a problem that the spring back generated on the standing wall 1 of the molded body is large due to the bending of the die shoulder.

  When used as a structural member, a molded body 10 having a cross-sectional hat shape having a standing wall 1 as shown in FIG. 7.a to FIG. 7.c has a metal plate disposed facing the hat head 2. The upper surface of the metal plate and the lower surface of the flange portion 3 are brought into contact with each other before joining. Accordingly, when the spring back of the molded body 10 having a cross-sectional hat shape is large, it is difficult to assemble the structural member. In FIG. 7.b to FIG. 7.c, W0 is the opening width of the molded body 10 having a hat-shaped cross section at the end of molding, and W is the opening width when taken out from the mold.

Therefore, the present inventors have proposed a method for processing a metal plate with little spring back (Patent Document 1 and the like).
JP 2002-66638 A

  The metal plate pressing method described in Patent Document 1 proposed by the present inventors can reduce spring back even when a metal plate material such as a high-tensile steel plate or an aluminum alloy plate is used. There is a problem that a press assist mold is necessary.

  The object of the present invention is to eliminate the above-mentioned problems of the prior art, and press working is performed on a metal plate material such as a high-tensile steel plate or an aluminum alloy plate using a mold in which a punch and a die are arranged to face each other. It is an object of the present invention to provide a metal plate pressing method capable of obtaining a cross-sectional hat-shaped formed body with less spring back even when applied.

The present invention is a method of pressing a metal plate using a die in which a punch and a die are arranged to face each other, and in obtaining a cross-sectional hat-shaped formed body having a standing wall, The plate material is passed along the die shoulder, bent by the die shoulder, and bent back to form the wall portion of the intermediate formed body having the hat head, the wall portion connected to both sides of the hat, and the flange portion, and so on. In the second molding process, the hat head portion of the intermediate molded body is clamped by a punch and a back pressure pad, and the flange portion of the intermediate molded body is clamped and constrained by a die and a wrinkle presser. Using a mold, first the hat head part is clamped by a punch and a back pressure pad, and the flange part is constrained by a die and a wrinkle presser. In this state, the distance between the flange part and the hat head part is Away By moving the second mold for molding direction, the portion of the hat the head of the preform was passed along a punch shoulder, bent by the punch shoulder, by molding bent back, the wall portion of the preform A press working method with less spring back, characterized in that a wall portion is formed by connecting to a wall.

  At that time, the ratio of the molding height increment in the second molding process and the molding height in the first molding process to the molding height of the standing wall is in the range of 0.1 to 0.4, It is preferable to form a standing wall.

  Hereinafter, as an embodiment of the present invention, a metal plate pressing method for obtaining a cross-sectional hat-shaped formed body 101 having a standing wall 1 as shown in FIG. 1.e will be described with reference to FIGS. 1.a to 1.d and This will be described with reference to FIGS. 2.a to 2.c.

  In the press working method according to the embodiment of the present invention, the wall portion 1A of the intermediate molded body 100 is formed in the first molding process as shown in FIGS. In the molding process, as shown in FIGS. 1.a to 1.d, the wall portion 1B is formed so as to be connected to the wall portion 1A of the intermediate molded body 100.

  In the first molding process, for example, as shown in FIGS. 2.a to 2.b, a wall of the intermediate molded body 100 as shown in FIG. Portion 1A can be formed. The intermediate molded body 100 includes a hat head portion 102, a wall portion 1A connected to both sides thereof, and a flange portion 103.

  In this case, the mold used in the first molding process is attached to the upper slide of the press device in which the die 112 can move in the vertical direction, and the punch 113 is attached to the lower bed of the press device. Further, the wrinkle presser 114 is connected to a hydraulic cylinder (not shown) via a rod, and is configured such that when the die 112 is lowered, the metal plate material 31 is sandwiched between the wrinkle pressers 114 with the die 112 and clamped with a predetermined pressing force. ing.

  The press working in the first molding process can be performed in the same manner as in the past. In the press working method using the mold described above, the die 112 is lowered with both sides in the width direction of the metal plate material 31 sandwiched between the die 112 and the wrinkle presser 14, the punch 113 is inserted into the die 112, and intermediate forming is performed. A wall portion 1A of the body 100 is formed. Thereafter, the mold is released, the intermediate molded body 100 is taken out from the mold, and the first molding process is completed.

  In such press working in the first forming process, when the die 112 is lowered, the metal plate material 31 is passed along the die shoulder 112a, bent by the die shoulder 112a, and bent back to form the wall portion 1A. is doing.

Here, the formed height h ₁ of the first molding process may be set in a press apparatus, the material passes through the length that has passed along the metal plate material 31 is die shoulder 112a is formed higher in the first molding process This corresponds to h ₁ . The hat head 102 of the intermediate molded body 100 is a portion that is not bent or unbent by the die shoulder 112a, and the interval between the wall portions 1A of the intermediate molded body 100 is a cross-sectional hat shape to be finally obtained. wider than the distance between the vertical wall 1 of the molded body 101 of the, also forming height h ₁ of the wall portion 1A of the preform 100 is lower than the forming height h of vertical wall 1 of the molded body 101 of the cross-sectional hat-shaped.

  Next, the second molding process will be described with reference to FIGS. 1.a to 1.d.

In the figure, P ₁ and P ₂ indicate the boundary between the first and second molding processes, and the boundary P ₁ is a wall portion on one side and the boundary P ₂ is a wall portion on the other side.

  The metal mold | die used for the press work of a 2nd shaping | molding process can install the metal mold | die which shape | molds the wall part 1B of one side, and the metal mold | die which forms the wall part 1B of the other side in another press apparatus. In the case of a continuous press having such a configuration, the wall portion 1B on one side is formed by the mold shown in FIG. 1.a and FIG. 1.b, and then the obtained compact is conveyed to the next press device. The wall portion 1B on the other side can be formed by the mold shown in 1.c to 1.d. According to such a configuration, it is possible to efficiently obtain the molded body 101 having a hat-shaped cross section.

  In that case, the dies 32 and 42, punches 33 and 43, wrinkle retainers 34 and 44, and back pressure pads 35 and 45 are used as molds. The die, punch, and wrinkle retainer are attached in the same manner as the mold used in the first molding process, and thus description thereof is omitted. The back pressure pads 35 and 45 can be metal plates, and are configured so as to be able to be sandwiched between the corresponding punch and the back pressure pad with the portion of the hat head 102 of the intermediate molded body 100 sandwiched therebetween. For example, a metal plate can be connected to a hydraulic cylinder via a rod and can be clamped with a predetermined pressing force.

  In the press working in the second molding process, the intermediate molded body 100 obtained in the first molding process is used and connected to the wall parts 1A on both sides of the intermediate molded body 100 to form the wall part 1B.

  First, as shown in FIG. 1.a, the hat head portion 102A of the intermediate molded body 100 is clamped by the punch 33 and the back pressure pad 35, and constrained by sandwiching the flange portion 103 with the die 32 and the wrinkle presser 34. State. In the pressing process in the second forming process in that state, the die 32 is lowered by a pressing device (not shown), the hat head portion 102A is passed along the punch shoulder 33a, bent by the punch shoulder 33a, and bent back. The wall portion 1B is formed by connecting to the wall portion 1A. At this time, the hat head portion 102B moves between the punch 33 and the back pressure pad 35, resulting in the state shown in FIG. Thereafter, the mold is released and the molded body is taken out from the mold.

Note that the pressing device, to set the forming height increment h ₂ of the second molding process.

  One side wall portion 1B formed in this way is a portion obtained by bending the hat head portion 102A with the punch shoulder 33a and bending back.

  Next, the obtained molded body is set in the next mold as shown in FIG. 1.c, the hat head portion 102C of the intermediate molded body 100 is clamped by the punch 43 and the back pressure pad 45, and the die 42 A state in which the flange portion 103 is sandwiched and restrained by the wrinkle presser 44 is assumed. In this state, in the pressing process of the second forming process, the die 32 is lowered, the hat head portion 102C is passed along the punch shoulder 33a, bent by the punch shoulder 33a, bent back and formed into the wall portion 1A. Connected to form the wall portion 1B. At that time, the portion 102B moves between the punch 43 and the back pressure pad 45, and the state shown in FIG. Thereafter, the mold is released, and the molded body 101 is taken out from the mold.

  The wall portion 1B on the other side formed in this way is a portion obtained by bending the hat head portion 102C with the punch shoulder 43a and bending it back.

  A standing wall 1 of a molded body 101 having a hat-shaped cross section obtained by a press working method according to an embodiment of the present invention is a wall portion 1A obtained by bending and bending back a metal plate material 31 with a die shoulder 112a in a first forming process. In the second molding process, the hat head portion 102A or 102C of the intermediate molded body 100 is bent by the punch shoulder 33a or 43a, and the wall portion 1B is formed by bending back. The wall portion 1A is a springback element that generates a springback in the direction in which the mouth opens when the die shoulder 112a is removed from the mold by a bending rod of the die shoulder 112a, whereas the wall portion 1B is a bent portion of the punch shoulder 33a or 43a. It is a spring go element that closes its mouth when it is removed from the mold by the scissors.

  Therefore, according to the press working method according to the embodiment of the present invention, the spring back element and the spring go element interact with each other at the time when the molded body 101 having the hat-shaped cross section is taken out from the mold, and the spring of the standing wall 1 The back can be reduced. According to such a press working method, even when a metal plate such as a high-strength steel plate or an aluminum alloy plate is used, the spring back element and the spring go element that constitute the standing wall 1 are present. Spring back can be reduced compared to processing.

In the second molding process, it is important to set the pressing force of the back pressure pads 35 and 45 appropriately. This is because if the pressing force of the back pressure pads 35 and 45 is excessive, the portion of the hat head portion 102 of the intermediate molded body 100 sandwiched between the back pressure pad and the punch cannot move, and the wall portion 1B is formed. This is because there may be a case where a breakage occurs in the middle of the process or a local reduction in the plate thickness occurs even if the breakage is not reached. Further, the flange portion 103, to a state of being constrained by the die and the blank-holder is the portion of the punch shoulder 33a or 43a of the hat head 102 only corresponding shaping to the height increment h ₂ of the second molding process This is for forming the wall portion 1B according to the punch shoulder passage length.

  Further, in the press working method of the present invention, the second molding process is not limited to the continuous press, but instead of the continuous press, the mold shown in FIGS. After forming the wall portion 1B, the other wall portion 1B can be formed using the same mold as shown in FIGS.

Next, according to FIG. 5, the molding height increment h ₂ in the second molding process / the molding height h ₁ in the first molding process is 0.1 to 0.4 relative to the molding height h of the standing wall 1. The reason why it is preferable to form the standing wall 1 will be described. FIG. 5 is a cross-sectional view obtained by changing the molding height h ₂ in the second molding process / the molding height h ₁ in the first molding process to various changes with the molding height h of the standing wall 1 constant at 70 mm. It is the graph which showed the result of the opening amount (W0-W) of the hat-shaped molded object.

  In the experiment, a molded body having a cross-sectional shape generally used as a structural member (forming height h = 70 mm of the standing wall 1 and opening width W0 = 60 mm of the cross-sectional hat-shaped molded body 101 at the end of molding) is pressed. Obtained by. Three types of materials applied as structural members shown in the figure were selected. However, W is the opening width when the molded body 101 having a hat-shaped cross section is taken out from the mold.

From the results shown in FIG. 5, in the conventional forming height increment h ₂ of the second molding process is zero method, although the amount of open mouth (W0-W) is about 15 to 20 mm, the depending on the material 2 By setting the molding height increment h _{2 in} the molding process to the molding height h ₁ in the first molding process in the range of 0.1 to 0.4, the opening amount (W0-W) can be close to 0 mm. I understand.

When the molding height increment h ₂ in the second molding process / the molding height h ₁ in the first molding process is less than 0.1, the improvement effect with respect to the conventional method is small, while the molding in the second molding process is small. When the height increment h ₂ / the molding height h ₁ in the first molding process exceeds 0.4, when the material used as the structural member is pressed and pressed, the spring on the standing wall of the molded body This is because the action of the go element becomes excessive and the mouth is closed.

  FIG. 6 shows the result of investigating the spring back of a hat having a cross-sectional hat shape by pressing a metal plate using a mold in which a die and a punch are arranged to face each other. As a parameter for evaluating the degree of springback, the opening amount (W0-W) was used. As materials, mild steel having a thickness of 1.6 mm and high-tensile steel plates having a thickness of 1.6 mm (tensile strength: 440 MPa, 590 MPa, 780 MPa) were used. The forming height h of the standing wall of the cross-sectional hat-shaped molded body is 70 mm, the opening width W0 of the cross-sectional hat-shaped molded body 101 at the end of molding is 60 mm, and the width of the flange portion is 15 mm.

In the case of the invention example, in the first molding process, as shown in FIGS. 2.a to 2.c, the opening width W0 of the molded body at the end of molding is 80 mm, the flange width is 15 mm, forming height forms a wall portion of the preform is h _1, a subsequent second molding step, as shown in FIG 1.a~ Figure 1.d, molded connecting the wall portions of the preform A wall portion having a height of h ₂ was formed. At that time, the pressing force of the back pressure pads 35 and 45 is 0.49 to 1.96 MPa (0.05 to 0.2 kgf / mm ² ) according to the tensile strength of the material per unit length of the intermediate molded body. In addition, the molding height increment h ₂ in the second molding process / the molding height h ₁ in the first molding process was adjusted in a range of 0.1 to 0.4 according to the tensile strength of the material.

  The cross-sectional dimensions of the punches 33 and 43 used in the second molding process were such that both the punch width was 60 mm and the radii of the punch shoulders 33a and 43a were both 5 mm. The radii of the die shoulders 32a and 42a of the dies used in the second molding process and the radius of the die shoulder 112a of the dies 112 used in the first molding process were 5 mm, respectively. The inner width of the die 112 used in the first molding process was 83.3 mm, and the cross-sectional dimensions of the punch 113 were a punch width of 80 mm and a radius of the punch shoulder 113a of 5 mm.

As a conventional example, as shown in FIGS. 8.a to 8.c, the metal plate material is passed along the die shoulder,
A standing wall of a molded body having a hat-shaped cross section was formed. In the mold used in the conventional example, the inner width of the die 12 was 83.3 mm, the radius of the die shoulder 12a of the die 12 was 5 mm, the punch width of the punch 13 was 80 mm, and the radius of the punch shoulder 13a was 5 mm.

  From the results shown in FIG. 6, in the case of the invention example, the opening amount (W0-W) of the shaped hat having a cross-sectional hat shape is significantly reduced compared to the conventional example, and the effect of suppressing the spring back is particularly large in a high-tensile steel plate. It is clear.

It is a figure explaining the 2nd shaping | molding process of the press work method which concerns on embodiment of this invention. It is a figure explaining the 2nd shaping | molding process of the press work method which concerns on embodiment of this invention. It is a figure explaining the 2nd shaping | molding process of the press work method which concerns on embodiment of this invention. It is a figure explaining the 2nd shaping | molding process of the press work method which concerns on embodiment of this invention. It is a figure explaining the shape of the molded object obtained by the press work method which concerns on embodiment of this invention. It is a figure explaining the 1st shaping | molding process of the press work method which concerns on embodiment of this invention. It is a figure explaining the 1st shaping | molding process of the press work method which concerns on embodiment of this invention. It is a figure explaining the 1st shaping | molding process of the press work method which concerns on embodiment of this invention. It is explanatory drawing in the case of forming the wall part of one side and the wall part of the other side using the same metal mold | die in a 2nd shaping | molding process. It is explanatory drawing in the case of forming the wall part of one side and the wall part of the other side using the same metal mold | die in a 2nd shaping | molding process. It is a graph explaining the suitable range in this invention. It is a graph which shows the effect of the present invention. It is a perspective view which shows an example of a molded object. It is a figure which shows the shape at the time of completion | finish of shaping | molding of a molded object. It is a figure explaining a spring back when a molded object is taken out from a metal mold | die. It is a figure for demonstrating the press work method using the conventional wrinkle presser, and shows the state just before drawing bending. It is a figure for demonstrating the press work method using the conventional wrinkle presser, and shows the state in the middle of drawing bending. It is a figure for demonstrating the press work method using the conventional wrinkle presser, and shows the state at the time of completion | finish of draw bending. It is a figure for demonstrating the conventional press processing method without a wrinkle suppression, and shows the state just before simple press bending molding. It is a figure for demonstrating the conventional press processing method without a wrinkle suppression, and shows the state in the middle of simple press bending. It is a figure for demonstrating the conventional press processing method without a wrinkle suppression, and shows the state in the middle of simple press bending. It is a figure for demonstrating the conventional press-working method without a wrinkle suppression, and shows the state at the time of completion | finish of simple press bending.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10, 101 Hat-shaped molded body 11, 21, 31 Metal plate material 100 Intermediate molded body 1 Standing wall 2, 102 Hat head 102A, 102B, 102C Hat head part 3, 103 Flange 1A First molding process 1B Wall part molded in the second molding process P1, P2 Boundary between the first and second molding processes h Molding height of the standing wall 1 h ₁ Molding height in the first molding process h ₂ Molding height increment in second molding process 12, 22, 32, 42, 112 Die 12a, 22a, 32a, 42a, 112a Die shoulder 13, 23, 33, 43, 113 Punch 13a, 23a, 33a, 43a, 113a Punch shoulder 14, 34, 44, 114 Wrinkle retainer 35, 45 Back pressure pad W0 Opening width of the molded body at the end of molding W Opening of molded body at the time of removal from the mold Width

Claims (2)

A method of pressing a metal plate using a mold in which punches and dies are arranged to face each other, and in order to obtain a cross-sectional hat-shaped formed body having a standing wall, in the first forming process, the metal plate material is die-molded. Passing along the shoulder, bending with the die shoulder, bending back forming, forming the wall portion of the intermediate molded body having the hat head portion, the wall portion connected to both sides thereof and the flange portion, and the subsequent second forming step Then, a second molding die is used in which the hat head portion of the intermediate molded body is clamped by a punch and a back pressure pad, and the flange portion of the intermediate molded body is clamped by a die and a wrinkle presser. First, the hat head part is clamped by a punch and a back pressure pad, and the flange part is constrained by a die and a wrinkle presser. In this state, the distance between the flange part and the hat head part is increased in the direction away from the first part. By moving the mold for molding, a portion of the hat the head of the preform was passed along a punch shoulder, bent by the punch shoulder, by molding bent back, and connecting the wall portions of the preform wall A press working method with less spring back characterized by forming a portion.   The standing wall is formed with the ratio of the molding height increment in the second molding process and the molding height in the first molding process in the range of 0.1 to 0.4 with respect to the molding height of the standing wall. The press working method with less spring back according to claim 1.

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