JP2022069861A - Press forming die and press forming method - Google Patents

Abstract

To suppress deformation of a long die during press molding and prevent deterioration of quality of formation, without increasing cost and size of a press forming die.SOLUTION: A press molding die 10 has long dies (bending dies 12, 13) and presses a workpiece (a side outer panel 1) in a direction crossing respective longitudinal directions of the bending dies 12, 13. Each of the bending dies 12, 13 is provided with driving means (an actuator 20) that applies compressive stress or tensile stress in the longitudinal direction.SELECTED DRAWING: Figure 4

Description

The present invention relates to a press forming die and a press forming method.

The side outer panel 1 of the vehicle body shown in FIG. 1 is usually formed by pressing from above and below in a flat state and performing drawing forming. Since the roof side rail 3 provided above the door opening 2 of the side outer panel 1 has a negative angle portion 4 as shown by a dotted line in FIG. 2, it can be formed by drawing forming by pressing in the vertical direction. Can not. Therefore, after the side outer panel 1 is drawn and molded, the negative angle portion 4 is often formed by bending using a slide mold (see, for example, Patent Document 1 below).

Japanese Unexamined Patent Publication No. 8-164420

The slide type for forming the roof side rail 3 as described above has a long shape extending in the front-rear direction of the vehicle body along the roof side rail 3. When a work is pressed in a direction orthogonal to the longitudinal direction with such a long slide type, the slide type may bend due to the reaction force of the press. When bending occurs in a long mold, the gap between the molding surfaces of the mold becomes excessive or too small, and the molding quality may deteriorate.

For example, if the strength (rigidity) of a long die is improved, bending during pressing can be suppressed. However, in order to increase the strength of the die, it is necessary to form the die with a high-strength material or increase the size of the die, which leads to an increase in cost and an increase in size of the press-molded die.

In view of the above circumstances, the present invention suppresses bending during press forming of a long die without increasing the cost and size of the press forming die, and prevents deterioration of forming quality. The purpose.

In order to solve the above-mentioned problems, the present invention is a press-molded die having a long die and pressing a work in a direction intersecting the longitudinal direction of the die, and the die is subjected to the longitudinal direction. Provided is a press forming die provided with a driving means for applying a compressive stress or a tensile stress.

By applying the compressive stress or the tensile stress in the longitudinal direction to the long mold by the above-mentioned driving means, the mold can be bent so that the intermediate portion in the longitudinal direction bulges. Therefore, the bending of the die can be suppressed by applying the compressive stress or the tensile stress in the longitudinal direction to the die by the driving means so as to cancel the bending generated in the die during press forming.

For example, if the portion of the long mold where bending occurs is pressed from behind (the side opposite to the work) with a cylinder or the like, the bending of the mold can be suppressed. However, in this case, since it is necessary to arrange a cylinder or the like behind the die, the size of the press-molded die may be increased, or the structure behind the die (for example, a cam mechanism for sliding the die) may be designed. It may need to be changed.

Therefore, it is preferable that the above-mentioned driving means has a first portion and a second portion that can move relative to each other, and the first portion and the second portion are attached to two locations separated in the longitudinal direction of the mold. .. By attaching the drive means to the long die itself in this way, it is not necessary to provide a cylinder or the like behind the die, so that it is possible to avoid an increase in size and design change of the press forming die.

For example, if a long die is designed in advance in anticipation of the amount of bending during pressing, the bending of the die during pressing can be suppressed. However, in the mold manufacturing process, the molding surfaces of the mold are aligned without a work to check the gap between the molding surfaces, and if the gap is not appropriate, the shape of the molding surface of the mold is corrected and the mold is again formed. Repeat the work of aligning the molding surfaces of the mold and checking the gap. For this reason, if the dies are formed in anticipation of bending during pressing, the formed surfaces of the dies do not match each other, and there is a possibility that the above-mentioned correction work of the formed surfaces cannot be performed.

Therefore, the present invention uses a press-molded die having a long die and a driving means for applying a compressive stress or a tensile stress in the longitudinal direction to the die, and a direction intersecting the longitudinal direction of the die. This is a press forming method in which a work is pressed into a die, and a gap between the forming surface of the die and the forming surface of another die facing the die without applying stress to the die by the driving means. Provided is a press forming method including a step of confirming the above and a step of pressing the work in a state where a compressive stress or a tensile stress in the longitudinal direction is applied to the die by the driving means.

In this way, by checking the gap between the molding surfaces of the mold without applying stress to the mold by the driving means, the molding surface of the mold can be modified as necessary. Then, when the work is pressed using this die, the bending of the die during pressing can be suppressed by applying the compressive stress or the tensile stress in the longitudinal direction to the die by the driving means.

As described above, according to the present invention, it is possible to suppress the bending of a long die during press forming without increasing the cost and increasing the size of the entire press forming die, so that the forming quality is deteriorated. Can be prevented.

It is a top view of the state where the side outer panel is placed flat. FIG. 3 is a cross-sectional view taken along the line AA of FIG. It is sectional drawing which shows the press forming die of a bending process, and shows the state before the descent start of the upper die. It is a top view of a bending die. It is a top view which shows the state of deformation of a bending die at the time of press molding. It is sectional drawing which shows the press forming die of a bending process, and shows the state in the process of lowering the upper die. It is sectional drawing which shows the press molding die of a bending process, and shows the state which the bending molding is completed by lowering the upper die to the lower end position. It is sectional drawing which shows the press forming die of a bending process, and shows the state which the upper die is raised to the upper end position.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

In the present embodiment, a case where the side outer panel 1 of the vehicle body of the automobile shown in FIG. 1 is press-molded is shown. The side outer panel 1 is formed through a draw forming step and a bending step. In particular, the roof side rail 3 provided above the door opening 2 of the side outer panel 1 has a negative angle portion 4 shown by a dotted line in a bending process after being formed into a shape shown by a solid line in FIG. 2 in a drawing forming process. It is molded. The draw forming step and the bending step are performed by lowering the upper die (not shown) from above with the side outer panel 1 placed flat. The right side of FIG. 2 is the upper side when the side outer panel 1 is assembled to the vehicle body, and the upper side is the outer side in the vehicle width direction when the side outer panel 1 is assembled to the vehicle body.

Hereinafter, the bending process for forming the negative angle portion 4 of the roof side rail 3 will be described. The bending step is performed using the press forming die 10 shown in FIG. The press forming die 10 includes a lower die 11, an upper die (not shown), an inner bending die 12, and an outer bending die 13. In the present embodiment, the lower mold 11 is a fixed type, and the upper mold is a movable type that can be raised and lowered in the vertical direction in the figure.

The inner bending die 12 and the outer bending die 13 intersect with the moving direction of the upper die (vertical direction in FIG. 3), and the longitudinal direction of the inner bending die 12 and the outer bending die 13 (direction orthogonal to the paper surface in FIG. 3). ) Is a slide type that can slide in the direction of intersection. In the illustrated example, the inner bending die 12 and the outer bending die 13 can move in the vertical direction and the direction orthogonal to the longitudinal direction (horizontal direction in FIG. 3). The upper mold is provided with a first cam (not shown) for driving the inner bending mold 12 and a second cam (not shown) for driving the outer bending mold 13.

The inner bending die 12 is provided with a forming surface 12a for forming the negative angle portion 4 and a cam surface (not shown) that comes into contact with the first cam provided on the upper die. The outer bending die 13 is provided with a forming surface 13a for forming the negative angle portion 4 and a cam surface (not shown) that comes into contact with the second cam provided on the upper die. By pushing down the cam surfaces of the inner bending die 12 and the outer bending die 13 with the first cam and the second cam, the inner bending die 12 and the outer bending die 13 move toward each other. The inner bending die 12 and the outer bending die 13 are urged to the sides separated from each other by an urging means such as a spring. When the first cam and the second cam are not in contact with the cam surfaces of the inner bending die 12 and the outer bending die 13, the inner bending die 12 and the outer bending die 13 are in contact with the lower die 11 and are separated from each other. Movement is restricted.

As shown in FIG. 4, the inner bending die 12 and the outer bending die 13 are long dies extending in the front-rear direction of the vehicle body. A driving means for applying compressive stress or tensile stress in the longitudinal direction (left-right direction in FIG. 4) is attached to the inner bending die 12 and the outer bending die 13. As the driving means, for example, an actuator 20 is provided. The actuator 20 has a cylindrical main body 21 (first portion) and a pin 22 (second portion) provided so as to be relatively movable with respect to the main body 21. As the actuator 20, a gas spring, a hydraulic cylinder, an electric cylinder, or the like can be used. In the actuator 20 mounted on the inner bending die 12, the main body 21 and the pin 22 are fixed to mounting portions 12b provided at two positions separated from each other in the longitudinal direction of the inner bending die 12. In the actuator 20 mounted on the outer bending die 13, the main body 21 and the pin 22 are fixed to mounting portions 13b provided at two positions separated from each other in the longitudinal direction of the outer bending die 13.

The actuator 20 attached to the inner bending die 12 is attached at a position offset to the molding surface 12a side from the center line L1 of the inner bending die 12 (a straight line passing through the center of gravity of the inner bending die 12 and along the longitudinal direction). .. The actuator 20 attached to the outer bending die 13 is offset from the center line L2 of the outer bending die 13 (a straight line passing through the center of gravity of the outer bending die 13 and along the longitudinal direction) away from the molding surface 13a. Attached to.

The actuator 20 of the inner bending die 12 may be mounted at a position offset from the center line L1 to the side away from the molding surface 12a. Further, the actuator 20 of the outer bending die 13 may be attached at a position offset to the molding surface 13a side from the center line L2. Alternatively, the actuator 20 may be provided on both sides of the center lines L1 and L2 of the bending dies 12 and 13. Further, the actuator 20 may be provided only in one of the inner bending die 12 and the outer bending die 13.

The number and position of the actuators 20 provided in the inner bending die 12 and the outer bending die 13, and the expansion / contraction amount of each actuator 20 are set based on the stress applied to the inner bending die 12 and the outer bending die 13 during pressing. Specifically, the internal stress applied to the inner bending die 12 and the outer bending die 13 when the side outer panel 1 is bent by the press forming die 10 is calculated by simulation. Then, the number, position, and expansion / contraction amount of the actuator 20 are set so that this internal stress is relaxed.

For example, when the long inner bending die 12 and the outer bending die 13 shown in FIG. 5 are pressed, the bending dies 12 and 13 are curved as shown by the dotted line due to the reaction force of the press (the curvature is exaggerated in FIG. 5). The compressive stress F1 is applied to the molding surfaces 12a and 13a on the side of the center lines L1 and L2, and the tensile stress F2 is applied to the side away from the molding surfaces 12a and 13a of the center lines L1 and L2. .. In this case, when the actuator 20 is provided on the molding surface 12a side of the center line L1 as in the inner bending die 12 shown in FIG. 4, the pin 22 of the actuator 20 is extended and the tensile stress in the longitudinal direction is applied to the die. By adding, the compressive stress F1 applied at the time of pressing is relaxed, and the bending of the inner bending die 12 is suppressed. On the other hand, when the actuator 20 is provided on the side away from the molding surface 13a from the center line L2 as in the outer bending die 13 shown in FIG. 4, the pin 22 of the actuator 20 is retracted to the mold in the longitudinal direction. By applying the compressive stress of, the tensile stress F2 applied at the time of pressing is relaxed, and the bending of the outer bending die 13 is suppressed.

After the press forming die 10 is installed in the factory, the forming surface 12a of the inner bending die 12 and the forming surface 13a of the outer bending die 13 are modified before the press forming is started. Specifically, the inner bending die 12 and the outer bending die 13 are not driven, that is, the inner bending die 12 and the outer bending die 13 are not subjected to longitudinal stress. The molding surface 12a of the 12 and the molding surface 13a of the outer bending die 13 are fitted together without sandwiching the work (side outer panel 1). In this state, the size of the gap between the molding surfaces 12a and 13a and the presence or absence of interference are confirmed. Then, if necessary, the molding surfaces 12a and 13a are shaved to correct the shape. After that, the molding surfaces 12a and 13a are fitted together without sandwiching the work again, and the gap between the molding surfaces 12a and 13a is confirmed. By repeating the above, the gap between the molding surfaces 12a and 13a is set to an appropriate value.

In this way, when the correction of the forming surfaces 12a and 13a of the bending dies 12 and 13 is completed, each actuator 20 is extended or retracted by the amount of expansion and contraction set above, and a predetermined stress is applied to each part of the bending dies 12 and 13. The bending molds 12 and 13 are deformed (curved). In this state, the bending step of the side outer panel 1 is performed. Hereinafter, the procedure of the bending process will be described.

First, as shown in FIG. 3, the side outer panel 1 that has undergone the drawing process is placed flat on the lower mold 11. At this time, the inner bending die 12 and the outer bending die 13 of the press forming die 10 are retracted to the positions where they abut on the lower die 11 or the stopper provided on the lower die 11, respectively. In this way, when the side outer panel 1 is set in the lower mold 11, the outer bending mold 13 is retracted to the side away from the inner bending mold 12 (right side in FIG. 3), so that the side outer panel 1 and the outer bending mold 13 are retracted. Interference with can be avoided.

Then, when the upper mold is lowered, the first cam comes into contact with the cam surface of the inner bending mold 12. When the upper mold is further lowered, the inner bending mold 12 is slid to the right side in the figure by the first cam and is arranged at a predetermined position. In the present embodiment, as shown in FIG. 6, the inner bending die 12 is arranged at a position where the inner bending die 12 abuts on the side outer panel 1 set on the lower die 11 (or a position immediately before the abutment). At this position, the inner bending die 12 is restricted from moving to the left side in the figure by the first cam.

After that, when the upper mold is further lowered, the second cam comes into contact with the cam surface of the outer bending mold 13. When the upper die is further lowered, the outer bending die 13 slides to the left side in the drawing by the second cam, and the roof side rail 3 of the side outer panel 1 has the forming surface 12a of the inner bending die 12 and the forming surface 13a of the outer bending die 13. The negative angle portion 4 is formed by being sandwiched between the two (see FIG. 7).

In this way, the side outer panel 1 is pressed by the long bending dies 12 and 13 in the direction intersecting the respective longitudinal directions (in the present embodiment, the direction substantially orthogonal to the longitudinal direction). The reaction force may cause bending of the bending dies 12 and 13 (see the dotted line in FIG. 5). In the present embodiment, the long bending dies 12 and 13 are deformed by applying compressive stress or tensile stress in the longitudinal direction in advance by the actuator 20, so that the shape is expected to be bent during pressing. At the time of pressing, the bending due to the stress of the actuator 20 and the bending due to the reaction force at the time of pressing are canceled out, so that the bending of the bending dies 12 and 13 is suppressed. As a result, the gap between the molding surfaces 12a and 13a of the bending dies 12 and 13 becomes close to a preset appropriate size, so that the quality of the bending process is improved. Further, even when molding a part having a large reaction force during pressing, the bending of the bending dies 12 and 13 can be suppressed without providing a structure for reinforcing the bending dies 12 and 13, so that the die structure is simplified. It can contribute to the conversion of molds and the weight reduction of molds.

When the upper die is lowered to the lower end position and then raised, the inner bending die 12 and the outer bending die 13 move away from the negative angle portion 4 of the side outer panel 1 due to the urging force of the urging means. Moving. Then, when the upper die is raised to the upper end position, the inner bending die 12 and the outer bending die 13 are retracted to a position where they do not overlap with the negative angle portion 4 in the pressing direction (vertical direction in the figure) (see FIG. 8). As a result, the side outer panel 1 on which the negative angle portion 4 is formed can be separated from the lifted lower mold 11.

In the above embodiment, the case where the long mold for applying the compressive stress or the tensile stress in the longitudinal direction by the driving means (actuator 20) is a slide type is not limited to this, and for example, the upper mold or the lower mold is used. It may be a long mold provided integrally with the mold.

Further, the present invention is not limited to the press forming die that performs bending processing, but can also be applied to a press forming die that performs other processing such as drawing processing and punching processing.

1 Side outer panel (work)
2 Door opening 3 Roof side rail 4 Negative angle part 10 Press forming die 11 Lower die 12 Inner bending die (long die)
13 Outer bending mold (long mold)
20 Actuator (driving means)
21 Main body (1st part)
22 pins (second part)

Claims (3)

A press-molded die having a long die and pressing a work in a direction intersecting the longitudinal direction of the die.
A press-molded die provided with a driving means for applying a compressive stress or a tensile stress in the longitudinal direction to the die. Claim 1 in which the driving means has a first portion and a second portion that can move relative to each other, and the first portion and the second portion are attached to two locations separated in the longitudinal direction of the mold. The press molding die described in. A press that presses a workpiece in a direction intersecting the longitudinal direction of the die using a press forming die having a long die and a driving means for applying a compressive stress or a tensile stress in the longitudinal direction to the die. It ’s a molding method.
A step of confirming a gap between the molding surface of the mold and the molding surface of another mold facing the molding surface of the mold without applying stress to the mold by the driving means.
A press forming method comprising a step of pressing the work in a state where a compressive stress or a tensile stress in the longitudinal direction is applied to the die by the driving means.

Images