Press molding method

Abstract

The present invention addresses the problem of easily molding a pillarless side outer panel.SOLUTION: The method includes a cutting process of cutting the cut portion 11 by upper blades 36A and 36B provided on the upper die 31 and lower blades 37A and 37B provided on the lower die 33 by relative movement of the upper die 31 and the lower die 33 in a pressing direction, and a drawing process of drawing the cut workpiece 10 by the upper die 31 and the lower die 33.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present invention relates to a press forming method. [Background technology]

[0002] The side outer panels that make up the side portions of a vehicle can be formed by processing sheet material using blanking, drawing, etc. If the left and right side outer panels have symmetrical shapes, they can be formed using a common molding die (for example, a common blanking die) in the molding process, which reduces the cost of the molding die.

[0003] For example, Patent Document 1 describes a multi-stage press device in which an upper die and a lower die, each consisting of an upper die and a lower die, are arranged in plane symmetry above and below, thereby forming plane-symmetric shapes between one side outer and the other side outer. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] WO2013 / 98927 publication Summary of the Invention [Problem to be solved by the invention]

[0005] In some vehicles, the pillar portion is eliminated from one of the side outer panels, resulting in different shapes for the left and right side outer panels. Therefore, if the workpieces are blanked using a common blanking die, the portion corresponding to the pillar portion remains on the side where the pillarless side outer panel is formed. This portion corresponding to the pillar portion causes problems with the formability of one of the side outer panels in subsequent processes such as drawing.

[0006] It is also possible to create separate blanking dies to create a pillarless workpiece and a workpiece with a portion corresponding to the pillar portion, and then perform drawing. However, creating separate blanking dies for each increases the cost of the forming dies.

[0007] In view of these circumstances, an object of the present invention is to form a pillarless side outer panel at low cost. [Means for solving the problem]

[0008] In order to solve the above problems, the present invention is characterized by being a press forming method including a cutting process in which a portion of the workpiece corresponding to a pillar portion is cut by relative movement between one forming die and the other forming die in the press direction, and a drawing process in which the workpiece after cutting is drawn using the one forming die and the other forming die.

[0009] In the present invention, by cutting the portion corresponding to the pillar portion before drawing, the drawing can be performed on the workpiece with the portion corresponding to the pillar portion removed. Therefore, even if press forming is performed using a workpiece having a portion corresponding to the pillar portion, a side outer panel can be formed without causing problems with formability in subsequent processes. This makes it possible to form the workpieces in the preliminary stages for forming a pillarless side outer panel and a side outer panel having a pillar portion using a common forming die and then input them into the press forming process. This reduces the cost of the forming die for forming the side outer panel.

[0010] Furthermore, the present invention allows the portion corresponding to the pillar section to be transported to a subsequent process together with the workpiece after drawing. This eliminates the need for equipment to collect or discard the cut portion corresponding to the pillar section during the press forming process, and allows the portion to be collected or discarded in a subsequent process. This reduces the cost of the press forming mold. [Effects of the Invention]

[0011] According to the present invention, a pillarless side outer panel can be formed at low cost. [Brief explanation of the drawings]

[0012] [Figure 1] 1(a) is a plan view showing the right side outer panel, and FIG. 1(b) is a plan view showing the left side outer panel. [Figure 2] FIG. 10 is a plan view showing the molding process of the left side outer panel. [Figure 3] FIG. 2 is a cross-sectional view showing the press mold of the present embodiment. [Figure 4] 10A and 10B are cross-sectional views showing a molding process using the press mold of the present embodiment, illustrating a state in which a pad abuts on a portion to be cut. [Figure 5] 1A to 1C are cross-sectional views showing a molding process using the press mold of the present embodiment, illustrating the state of the portion to be cut when being cut. [Figure 6] 1A to 1C are cross-sectional views showing the forming process using the press mold of the present embodiment, illustrating the state during drawing. [Figure 7] FIG. 10 is a cross-sectional view showing the forming process using the press mold of this embodiment, showing the state in which the upper mold has been retracted after drawing. [Figure 8] 1A and 1B are cross-sectional views showing a molding process using the press mold of the present embodiment, illustrating the state of the intermediate molded product and the portion to be cut before being transported by the transport device. [Figure 9] 1A to 1C are cross-sectional views showing a molding process using the press mold of the present embodiment, illustrating the state when the intermediate molded product and the portion to be cut are being transported by the transport device. DETAILED DESCRIPTION OF THE INVENTION

[0013] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0014] FIG. 1(a) is a plan view showing a right (other side) side outer panel 1R, and FIG. 1(b) is a plan view showing a left (other side) side outer panel 1L formed by the press forming method of this embodiment.

[0015] As shown in Figures 1(a) and 1(b), side outer panel 1R has a pillar portion 1A, while side outer panel 1L does not have a pillar portion. The pillar portion of the side outer panel is a column portion that extends vertically at the center of the side outer panel (between the front seat side and rear seat side of the vehicle) and connects the upper part of the side outer panel, which is the roof side, with the lower part, which is the rocker side.

[0016] The side outer panel 1L of this embodiment is formed by drawing out a coil material, that is, a rolled steel sheet, and processing it by press forming or the like.

[0017] 2(a) to 2(c) are plan views showing the forming process of the left side outer panel 1L. The workpiece 10 in FIG. 2(a) is a plate-shaped workpiece formed by blanking from a coil material. A similar workpiece 10 is used to form the side outer panel 1R in FIG. 1(a). By performing the press forming method of this embodiment on the workpiece 10, an intermediate formed product 20 (workpiece after drawing) shown in FIG. 2(b) is obtained. During this press forming, a cut portion 11, which corresponds to the pillar portion of the final formed product, is cut. After press forming, processes such as trimming and bending are performed to form the final formed product, the side outer panel 1L.

[0018] The press mold of this embodiment for press-forming the workpiece 10 will be described with reference to Fig. 3, and the press-forming method of this embodiment will be described with reference to Figs. 4 to 9. Figs. 3 to 9 show a portion of the workpiece 10 corresponding to the cross-sectional line A-A in Fig. 2.

[0019] As shown in Figure 3, the press molding die 30 includes an upper die 31 as one of the molding dies, an upper die slider 32, a lower die 33 as the other molding die, a bolster 34, pads 35A and 35B as support parts, upper blades 36A and 36B which are shearing parts (cutting parts) provided on the upper die 31, lower blades 37A and 37B which are shearing parts (cutting parts) provided on the lower die 33, and a lifter 38 which is an elevation means provided on the upper die.

[0020] The upper die slider 32 supports the upper die 31 so that it can move up and down. The bolster 34 supports the lower die 33 from below. The lower die 33 has a movable part 33A that moves up and down and a fixed part 33B. The movable part 33A rises when pressed by multiple cushion pins 39 and descends when pressed by the upper die 31. The fixed part 33B has a drawing part 33B1 that presses the workpiece 10 to perform drawing. The pads 35A and 35B support the portion to be cut 11 from above. The upper blades 36A and 36B and the lower blades 37A and 37B generate shear forces between the portion to be cut 11 supported by the pads 35A and 35B and the rest of the workpiece 10, separating the portion to be cut 11 from the workpiece 10. The pads 35A and 35B and the upper blades 36A and 36B are held by the upper die 31 and move up and down together with the upper die 31. Pads 35A and 35B are held by upper die 31 via springs 41, and can move up and down relative to upper die 31 by expansion and contraction of spring 41. Lower blades 37A and 37B and lifter 38 are held by movable part 33A of lower die 33, and move up and down together with movable part 33A. Furthermore, lifter 38 is provided so as to be movable up and down relative to movable part 33A, and can move cut portion 11 upward after cutting. Note that the up and down direction in FIG. 3, which is the pressing direction of press-forming die 30, does not necessarily refer to the direction of gravity or the opposite direction.

[0021] First, as shown in FIG. 3 , the workpiece 10 is placed on the lower die 33. In this state, the lower blades 37A and 37B are in contact with the underside of the workpiece 10. From this state, the upper die 31 is lowered by the upper die slider 32, causing the pads 35A and 35B to contact the portion 11 to be cut of the workpiece 10 from above, supporting the workpiece 10 from above, as shown in FIG. 4 . Then, by further lowering the upper die 31, the upper blades 36A and 36B come into contact with the upper surface of the workpiece 10. By applying a force to lower the upper die 31 in this state, the portion 11 to be cut of the workpiece 10 is sheared by the upper blades 36A and 36B and the lower blades 37A and 37B, as shown in FIG. 5 , and the portion 11 is separated from the rest of the workpiece 10. The upper blades 36A and 36B and the lower blades 37A and 37B are adjacent to each other and press the workpiece 10 from different sides, generating a shear force on the workpiece 10. 4 to the position shown in FIG. 5, the pads 35A and 35B are subjected to a compressive force between the upper die 31 and the lower blades 37A and 37B. As a result, the springs 41 connected to the pads 35A and 35B are compressed by the amount that the upper die 31 is lowered, and the pads 35A and 35B support the workpiece 10 at the position shown in FIG. 4. In addition, in the states shown in FIGS. 4 and 5, the upper die 31 is not in contact with the workpiece 10.

[0022] In particular, in this embodiment, as shown in FIG. 5 , the shearing of the portion to be cut 11 is performed immediately before the upper die 31 contacts the workpiece 10, i.e., immediately before drawing. This minimizes bending of the portion to be cut 11 after cutting. Unlike this embodiment, by protruding the upper blades 36A and 36B further downward, the portion to be cut 11 can be sheared at an earlier timing. However, in this case, after the portion to be cut 11 is sheared, while the upper die 31 descends to the position shown in FIG. 5 where it contacts the lower die 33, the end of the portion to be cut 11 is pressed downward by the upper blades 36A and 36B and bent. This makes it more difficult to recover the portion to be cut 11 in a subsequent process than in a plate-like state, and makes it more difficult to reuse the portion to be cut 11 thereafter. In contrast, in this embodiment, by minimizing bending of the portion to be cut 11 as described above, the recovery and reuse of the portion to be cut 11 in a subsequent process is facilitated.

[0023] When the upper die 31 is lowered from the position shown in Figure 5, the upper die 31 comes into contact with the top surface of the workpiece 10, and then the movable part 33A of the lower die 33 also descends as the upper die 31 descends. At this time, the part to be cut 11 descends integrally while being clamped between the pads 35A, 35B and the lower blades 37A, 37B. Then, the drawing part 33B1 fixed to the fixed part 33B of the lower die 33 presses against the bottom surface of the workpiece 10, thereby performing the drawing process. As a result, the intermediate formed product 20 is formed, as shown in Figure 6.

[0024] When the upper die 31 reaches the bottom dead center position in Figure 6 and drawing is completed, the upper die 31 is retracted upward as shown in Figure 7. Also, the movable part 33A is pushed out by the cushion pins 39 and moves upward, lifting the intermediate molded product 20. Also, the lifter 38 rises relative to the movable part 33A and moves the part to be cut 11 upward. In other words, the part to be cut 11 is lifted upward by the rise of the movable part 33A and the lifter 38, and moves upward relative to the intermediate molded product 20.

[0025] After the drawing process, as shown in Fig. 8, the conveying device 40 is moved above the intermediate molded product 20 and the portions to be cut 11. Then, as shown in Fig. 9, the conveying device 40 holds the intermediate molded product 20 and the portions to be cut 11 and conveys them to a subsequent process. The conveying device 40 holds the intermediate molded product 20 and the portions to be cut 11, for example, by suction. Thereafter, the side outer panel 1L (see Fig. 2(c)) is formed through a trimming process, a bending process, and a punching process.

[0026] As described above, the press-forming die 30 of this embodiment can cut the cut portion 11 from the plate-shaped workpiece 10 before drawing. However, if drawing is performed while leaving the cut portion 11, there is a problem in that the material does not sufficiently flow into the vertical wall formed at the position corresponding to the connection between the cut portion 11 and the rocker side (portion 1B in FIG. 1(b)), which can cause cracks in portion 1B after forming. In this embodiment, drawing can be performed on the workpiece 10 with the cut portion 11 previously separated by the shearing (cutting) process, preventing such cracks from occurring. In other words, even when using a workpiece 10 having the cut portion 11, processing using the press-forming die 30 can produce an intermediate formed product 20 with good formability. Therefore, a common workpiece 10 can be used for the side outer panel 1R and the side outer panel 1L, and a common blanking die can be used. This reduces the cost of the blanking die. Furthermore, the portion to be cut 11 can be sheared simply by adding the pads 35A, 35B, upper blades 36A, 36B, and lower blades 37A, 37B to the press mold 30, without providing a separate cutting process. This reduces the processing cost. While the above description focuses on cracks on the rocker side of the side outer panel 1L, similar cracks may occur at the connection with the pillar portion on the roof side.

[0027] Furthermore, in this embodiment, when the conveying device 40 conveys the intermediate molded product 20 to the subsequent process, the portion to be cut 11 is also conveyed to the subsequent process at the same time. As a result, in the drawing process using the press mold 30, there is no need to provide a separate mechanism for disposing of the portion to be cut 11, and it becomes possible to remove the portion to be cut 11 from the press mold 30. Furthermore, the portion to be cut 11 is collected together with unnecessary parts generated in the processing process, such as trimming. Therefore, there is no need to provide separate equipment for disposing of the portion to be cut 11 in the subsequent process either.

[0028] Furthermore, in this embodiment, the lifter 38 raises the part to be cut 11, thereby enabling the holding position of the part to be cut 11 by the conveying device 40 to be raised. Therefore, if the movement trajectory of the part to be cut 11 held by the conveying device 40 overlaps with equipment such as the press molding die 30, the lifter 38 can raise the part to be cut 11 to a desired height, thereby preventing interference between the part to be cut 11 and the equipment.

[0029] Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and it goes without saying that various modifications can be made without departing from the spirit of the present invention. [Explanation of symbols]

[0030] 1L Side outer panel 10 Work 11 Cutting section (part corresponding to pillar section) 20 Intermediate formed product (workpiece after drawing) 30 Press mold 31 Upper mold (one of the molding molds) 33 Lower mold (other molding mold) 35A, 35B Pad (support part) 36A, 36B Upper blade (shearing part) 37A, 37B Lower blade (shearing part)

Claims

1. a cutting step of cutting a portion of the workpiece corresponding to a pillar portion by relative movement of one mold and the other mold in the press direction; a drawing step of drawing the workpiece after cutting using the one forming die and the other forming die.

2. 2. The press forming method according to claim 1, wherein the portion corresponding to the pillar portion is transported to a subsequent process together with the workpiece after drawing.

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