Springback control method for slotted internal punching dies in aluminum alloy automotive body panels

Abstract

This invention relates to a method for controlling the springback of an aluminum alloy automotive body panel slot punching die, comprising the following steps: S1, filling with a three-moving wedge; S2, applying a constant load to sections AB and BC of workpiece (1); S3, applying a rotating wedge to section CD of workpiece (1), avoiding the waste outlet space on the waste slide base (15) during the pressing process; S4, using an upper pressure source to perform suspended punching on section CD of workpiece (1) fitted with a slot-shaped contour block (6); S5, after punching is completed, sections BC and CD of workpiece (1) are held under pressure by a delayed nitrogen spring device (10). This method effectively ensures the springback warpage of the rounded corner areas of the slot side and bottom, while also stabilizing the control of aluminum chips and punching burrs. The existing method for eliminating springback defects in aluminum alloy dies relies on manual adjustment of process parameters, which reduces die debugging efficiency and increases die development costs.

Description

Technical Field

[0001] This invention relates to a method for controlling the springback of an aluminum alloy automotive body panel slot-shaped internal punching die, belonging to the field of die technology. Background Technology

[0002] Aluminum alloy automotive body panels differ from ordinary steel sheets in terms of ductility, springback, surface wear, and shear performance. The springback during stamping is significant, and aluminum sheet punching easily generates aluminum chips, damaging the die surface and affecting product appearance quality. Springback defects further complicate the improvement of punching quality and aluminum chip control. Especially for Z-shaped, channel-shaped, and I-shaped structures, significant springback defects can be reduced or eliminated through process measures or tooling fixtures. However, the flange CD at the end of the body die for large aluminum alloy automotive body panels has an inward-flaring design, a typical channel shape. Due to the stamping process, the irregular punching on the flange must be completed within the narrow channel, requiring the use of non-standard, custom-made punches. This not only complicates the structural design but also, due to the large size of the irregular holes, generates significant springback during punching, as well as increased punching burrs and aluminum chips, leading to deviations in the dimensional and positional accuracy of the punched holes. Currently, reducing or eliminating springback defects in aluminum alloy molds relies on adjustments to process parameters by fitters, which severely reduces mold debugging efficiency and increases mold development costs. Summary of the Invention

[0003] The technical problem to be solved by this invention is that the springback defect of existing aluminum alloy molds is eliminated by adjusting process parameters by fitters, which reduces the efficiency of mold debugging and increases the development cost of molds.

[0004] The technical solution adopted by this invention to solve its technical problem is: a method for controlling the springback of an aluminum alloy automotive body panel slot-shaped internal punching die, comprising the following steps:

[0005] S1. Use a three-moving wedge to fill the workpiece ABCDE;

[0006] S2. Apply constant load to the workpiece sections AB and BC;

[0007] S3. Use a rotating wedge to press the workpiece CD section, avoiding the waste outlet space on the waste slide base during the pressing process;

[0008] S4. The workpiece CD segment, into which the grooved contour block is fitted, is suspended and punched using the pressure source at the top.

[0009] S5. After punching is completed, the workpiece sections BC and CD are pressure-maintained by a delayed nitrogen spring device.

[0010] In the above method, step S1 involves filling the workpiece with the groove-shaped contour block from the three-moving wedge.

[0011] In step S2 of the above method, when the workpiece is placed between the upper die pressure plate and the groove-shaped contour block, the three-moving wedge inserter slides along the longitudinal guide plate under the drive of the longitudinal cylinder. The three-moving wedge drive guide plate is composed of a friction pair consisting of the inserter guide plate inclined surface MN and the drive seat guide plate surface PQ. When point M contacts point P, it pushes the three-moving wedge drive seat to slide obliquely on the inclined guide plate. The groove-shaped contour block is installed on the three-moving wedge drive seat. When point N of the three-moving wedge drive guide plate is aligned with point P, the stroke of the drive seat reaches the bottom, and the groove-shaped contour block reaches the pressure position.

[0012] Furthermore, in step S2 of the above method, the upper mold pressure device 7 performs the pressing of section AB under the action of the upper mold nitrogen spring, and the delayed nitrogen spring device pushes the cylinder to press the BC section surface.

[0013] In step S3 of the above method, the rotating wedge body is driven by an external air circuit to rotate on the waste slide base. Under the continuous pressure of the external air circuit, the pressing surface of the body contacts the lower end of DE, so that the nitrogen spring compression stroke of the rotating wedge return drive device reaches the maximum.

[0014] In step S4 of the above method, after the material is pressed into place on each surface, the upper die pressure plate continues to press down under the action of the upper die. The punching pressure plate on the groove-shaped contour block presses down on the upper surface of DE under the action of the pressure nitrogen spring. The punch on the punch holder contacts the workpiece. The upper die pressure plate continues to press down. Since the pressure of the upper die nitrogen spring is greater than the pressure of the suspension block nitrogen spring, the entire groove-shaped contour block performs punching work. The punching ends when the lower suspension block nitrogen spring is compressed to the bottom.

[0015] In the above method, after punching, step S5 holds pressure on sections BC and DE of the workpiece. The pressure of the nitrogen spring of the upper die is greater than the pressure of the nitrogen spring of the suspension block. The holding time of section DE is equal to the compression stroke release time of the upper die pressure device. The holding time of section BC is achieved by using a delayed nitrogen spring device.

[0016] The above method also includes step S6, mold opening and part removal.

[0017] Furthermore, in step S6 of the above method, after the springback and pressure holding are completed, the mold is opened. The return stroke of the upper mold nitrogen spring 8 and the suspension block nitrogen spring causes the grooved contour block to float to the pressing position. The delayed nitrogen spring device returns to the initial state under the drive of the external air circuit. The rotating wedge body returns to the initial position under the pressure release of the rotating wedge return drive device. The rotating wedge return drive device includes a return nitrogen spring, a limit baffle and a return pressure plate. The return stroke is achieved by the return pressure plate. The limit baffle provides limit constraint. When the upper mold continues to return, the three-moving wedge insert is pulled back by the longitudinal cylinder, driving the three-moving wedge drive seat and the grooved contour block to return according to the predetermined reciprocating stroke until the M and P points of the two guide plate inclined surfaces return to the initial position.

[0018] Furthermore, in step S6 of the above method, the finished product is picked up by a robotic arm end effector.

[0019] The beneficial effects of this invention are as follows: This method reduces the springback defect of the internal punching die for the groove-shaped feature parts of large automotive aluminum alloy body panels. It improves the die structure by first using a three-moving wedge for filling, and then using a delayed nitrogen spring device and a rotating wedge to apply constant load to the side and bottom surfaces respectively. The punching operation is carried out using a suspended structure of the groove-shaped contour block. After punching, the side surfaces are held under pressure for a delayed time using a delayed nitrogen spring device, and the pressure holding time of the bottom surface depends on the compression stroke release time of the upper die pressure platen. This effectively ensures the springback warpage of the rounded corner areas of the groove side and bottom surfaces, while also stabilizing the control of aluminum chips and punching burrs. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the internal punching structure of the groove-shaped part of the back door outer panel of the present invention.

[0021] Figure 2 This is a schematic diagram of the three-moving inclined wedge driving structure of the present invention.

[0022] Figure 3 This is a schematic diagram of the punching working structure of the present invention.

[0023] Figure 4 For the present invention Figure 3 A schematic diagram of the AA cross-sectional structure.

[0024] Reference numerals in the attached diagram: 1 is the workpiece, 2 is the longitudinal guide plate pair, 3 is the three-moving wedge drive seat, 4 is the three-moving wedge inserter, 5 is the three-moving wedge drive guide plate, 6 is the groove-shaped contour block, 7 is the upper die pressure plater, 8 is the upper die nitrogen spring, 9 is the upper die, 10 is the delayed nitrogen spring device, 11 is the punch fixing seat, 12 is the punching pressure plate, 13 is the rotating wedge body, 14 is the rotating wedge return drive device, 15 is the waste material slide base, 16 is the suspension block nitrogen spring, 17 is the inclined guide plate, 18 is the return nitrogen spring, 19 is the limit baffle, 20 is the return pressure plate, 21 is the pressure nitrogen spring, and 22 is the longitudinal cylinder. Detailed Implementation

[0025] The invention will be further described below with reference to the accompanying drawings.

[0026] like Figures 1 to 4 As shown, the springback control method of the aluminum alloy automotive body panel slot-shaped inner punching die of the present invention includes the following steps:

[0027] S1. Use a three-moving wedge to fill the workpiece 1ABCDE;

[0028] S2. Apply constant load to workpiece 1AB and BC segments;

[0029] S3. Use a rotating wedge to press the workpiece 1CD section, avoiding the waste outlet space on the waste slide base 15 during the pressing process;

[0030] S4. The workpiece 1CD segment, into which the grooved contour block 6 is fitted, is suspended and punched using the pressure source at the top.

[0031] S5. After punching, sections 1BC and CD of the workpiece are held under pressure by a delayed nitrogen spring device 10. Those skilled in the art will understand that in this method, step S1 uses a three-moving wedge for filling; step S2 uses the delayed nitrogen spring device 10 and a rotating wedge to apply constant loads to the side and bottom surfaces respectively; step S4 uses the suspension structure of the grooved contour block 6 for punching; after punching in step S5, the side surfaces are held under pressure by the delayed nitrogen spring device 10, and the pressure holding time on the bottom surface depends on the compression stroke release time of the upper die pressure plate 7, effectively ensuring the springback warpage of the rounded corner areas of the grooved side and bottom surfaces, while also stably controlling aluminum chips and punching burrs. Furthermore, S5 primarily aims to ensure the springback warpage of the rounded corner areas at both ends of BC.

[0032] Preferably, in step S1 of the above method, the grooved contour block 6 of the three-moving wedge is filled into the workpiece 1. Those skilled in the art will understand that step S1 actually involves filling the grooved contour block 6 of the three-moving wedge into the workpiece 1, ensuring the internal filling of the workpiece 1 and preventing deformation due to pressure.

[0033] Preferably, in step S2 of the above method, when the workpiece 1 is placed between the upper die pressure plate 7 and the groove-shaped contour block 6, the three-moving wedge insert 4 slides along the longitudinal guide plate pair 2 under the drive of the longitudinal cylinder 22. The three-moving wedge drive guide plate 5 consists of a friction pair formed by the insert guide plate inclined surface MN and the drive seat guide plate surface PQ. When point M contacts point P, it pushes the three-moving wedge drive seat 3 to slide on the inclined guide plate 17. The groove-shaped contour block 6 is installed on the three-moving wedge drive seat 3. When point N of the three-moving wedge drive guide plate 5 is aligned with point P, the stroke of the drive seat reaches its limit, and the groove-shaped contour block 6 reaches the pressing position. Those skilled in the art will understand that the specific operation in step S2 of this method is further preferred, and this step S2 is mainly the pressing action of the AB and BC sections of the workpiece 1 before punching. The pressing action is divided into pre-pressing and pressing. This is the pre-pressing process: Specifically, when the workpiece from the previous process is placed between the upper die presser 7 and the grooved contouring suspension block 6, the three-moving wedge insert 4 slides along the longitudinal guide plate pair 2 under the drive of the longitudinal cylinder 22. Here, the three-moving wedge drive guide plate 5 is composed of the insert guide plate inclined surface MN and the drive seat guide plate surface PQ forming a friction pair. When point M contacts point P, it pushes the three-moving wedge drive seat 3 to slide obliquely on the inclined guide slide plate 17. The grooved contouring suspension block 6 is installed on the three-moving wedge drive seat 3 with screws. When point N of the three-moving wedge drive guide plate 5 is aligned with point P, the stroke of the drive seat 3 reaches the bottom, and the grooved contouring suspension block 6 reaches the pressing position to realize the pre-pressing operation.

[0034] Preferably, in step S2 of the above method, the upper die pressure device 7 presses the material for segment AB under the action of the upper die nitrogen spring 8, and the delayed nitrogen spring device 10 pushes the cylinder to press the BC segment surface. Those skilled in the art will understand that in this step, segments AB and BC are primarily pressed by the upper die nitrogen spring 8 and the delayed nitrogen spring device 10; specifically, the upper die pressure device 7 presses the material for segment AB under the action of the upper die nitrogen spring 8, and the delayed nitrogen spring device 10 pushes the cylinder to press the BC segment surface.

[0035] Preferably, in step S3 of the above method, the rotating wedge body 13 is driven by an external air circuit to rotate on the waste material slide base 15. Under continuous pressure from the external air circuit, the main body's pressing surface contacts the lower end of DE, causing the nitrogen spring compression stroke of the rotating wedge return drive device 14 to reach its maximum. Those skilled in the art will understand that step S3 mainly involves the pressing action of the DE section of the pre-punching profile. The pressing action of the DE section is primarily achieved using a rotating wedge. The rotating wedge body 13 is driven by an external air circuit to rotate on the waste material slide base 15. Under continuous pressure from the external air circuit, the main body's pressing surface contacts the lower end of DE, at which point the nitrogen spring compression stroke of the rotating wedge return drive device 14 reaches its maximum.

[0036] Preferably, in step S4 of the above method, after the material is pressed into place on each profile, the upper die pressure plate 7 continues to press down under the action of the upper die 9. The punching pressure plate 12 on the groove-shaped contour block 6 presses down on the upper profile of DE under the action of the pressure nitrogen spring 21. The punch on the punch holder 11 contacts the workpiece 1, and the upper die pressure plate 7 continues to press down. Since the pressure of the upper die nitrogen spring 8 is greater than the pressure of the suspension block nitrogen spring 16, the groove-shaped contour block 6 performs punching work as a whole. The punching ends when the lower suspension block nitrogen spring 16 is compressed to the bottom. Those skilled in the art will understand that this step is mainly about punching work. After the material is pressed into place on each surface, the upper die pressure plate 7 continues to press down under the action of the upper die 9. The punching pressure plate 12 on the groove-shaped contouring suspension block 6 presses down on the upper surface of DE under the action of the pressure nitrogen spring 21. The punch on the punch fixing seat 11 contacts the product in the process. When the upper die pressure plate 7 continues to press down, since the pressure of the upper die nitrogen spring 8 is greater than the pressure of the suspension block nitrogen spring 16, the groove-shaped contouring suspension block 6 performs punching work as a whole. When the lower suspension block nitrogen spring 16 is compressed to the bottom, the punching work ends.

[0037] Preferably, in the above method, after punching, step S5 applies pressure to sections BC and DE of the workpiece 1. The pressure of the upper die nitrogen spring 8 is greater than the pressure of the suspension block nitrogen spring 16. The pressure holding time of section DE is equal to the compression stroke release time of the upper die pressure feeder 7. The pressure holding time of section BC is achieved using the delayed nitrogen spring device 10. Those skilled in the art will understand that step S5 mainly controls the springback pressure holding of sections BC and DE. After punching, to reduce springback defects caused by the release of external force after punching, it is necessary to apply pressure to sections BC and DE to reduce springback defects. Since the pressure of the upper die nitrogen spring 8 is greater than the pressure of the suspension block nitrogen spring 16, it can be seen that the pressure holding time of the section DE mechanism mainly depends on the compression stroke release time of the upper die pressure feeder 7. The pressure holding time of section BC mainly uses the delayed nitrogen spring device 10, which mainly includes a nitrogen spring body, a zero-springback device, and a controller.

[0038] Preferably, the above method further includes step S6, which involves opening the mold and removing the part. Those skilled in the art will understand that, to facilitate the removal of workpiece 1, this method preferably includes step S6, which mainly involves opening the mold and removing the part.

[0039] Preferably, in step S6 of the above method, after the springback and pressure holding are completed, the mold is opened. The return of the upper mold nitrogen spring 8 and the suspension block nitrogen spring 16 causes the groove-shaped contour block 6 to float to the pressing position. The delayed nitrogen spring device 10 returns to the initial state under the drive of the external air path. The rotating wedge body 13 returns to the initial position under the pressure release of the rotating wedge return drive device 14. The rotating wedge return drive device 14 includes a return nitrogen spring 18, a limit baffle 19 and a return pressure plate 20. The return stroke is achieved by the return pressure plate 20 and the limit baffle 19 provides limit constraint. When the upper mold 9 continues to return, the three-moving wedge insert 4 is pulled back by the longitudinal cylinder 22, driving the three-moving wedge drive seat 3 and the groove-shaped contour block 6 to return according to the predetermined reciprocating stroke until the M and P points of the two guide plate inclined surfaces return to the initial position. Those skilled in the art will understand that after the springback holding pressure ends, the mold opens. First, the upper mold nitrogen spring 8 and the suspension block nitrogen spring 16 return, causing the groove-shaped contour suspension block 6 to float to the pressing position. Second, the delayed nitrogen spring device 10 returns to its initial state under the drive of the external air path. In addition, the rotating wedge body 13 returns to its initial position under the pressure release of the rotating wedge return drive device 14. It should be noted that the rotating wedge return drive device 14 includes three components: a return nitrogen spring 18, a limiting baffle 19, and a return pressure plate 20. Its return stroke is achieved by the return pressure plate 20, and considering the inertial impact, it is limited and constrained by the limiting baffle 19. As the upper die 9 continues to retract, the three-moving wedge insert 4, under the pull of the longitudinal cylinder 22, drives the three-moving wedge drive seat 3 and the groove-shaped contouring suspension block 6 to retract according to the predetermined reciprocating stroke until the M and P points of the two guide plate inclined surfaces retract to the initial position. At this time, the finished product can be grabbed and placed into the next process product to carry out the next punching work cycle.

[0040] Preferably, in step S6 of the above method, the finished product is picked up by a robotic arm end effector. Those skilled in the art will understand that, for the convenience of picking up and placing workpiece 1, this method preferably uses a robotic arm end effector to pick up the finished product.

Claims

1. A method for controlling the springback of a die for punching grooves in aluminum alloy automotive body panels, characterized in that... Includes the following steps: S1. Use a three-moving wedge to fill the workpiece (1) ABCDE; S2. Apply constant load to the workpiece (1) sections AB and BC; S3. Use a rotating wedge to press the workpiece (1) CD section, avoiding the waste outlet space on the waste slide base (15) during the pressing process; S4. The workpiece (1) CD segment fitted into the grooved molding block (6) is suspended and punched by the pressure source at the top. S5. After punching is completed, the workpiece (1) BC and CD sections are pressure-held by the delayed nitrogen spring device (10); In step S2, when the workpiece (1) is placed between the upper die presser (7) and the groove-shaped contour block (6), the three-moving wedge insert (4) slides along the longitudinal guide plate pair (2) under the drive of the longitudinal cylinder (22). The three-moving wedge drive guide plate (5) is composed of the insert guide plate inclined surface MN and the drive seat guide plate surface PQ forming a friction pair. When point M contacts point P, it pushes the three-moving wedge drive seat (3) to slide on the inclined guide plate (17). The groove-shaped contour block (6) is installed on the three-moving wedge drive seat (3). When the three-moving wedge drive guide plate (5) When point N aligns with point P, the drive seat reaches its limit, and the grooved contour block (6) reaches the pressing position; in step S2, the upper die pressing device (7) presses the material in section AB under the action of the upper die nitrogen spring (8), and the delayed nitrogen spring device (10) pushes the cylinder to press the BC section surface; in step S3, the rotating wedge body (13) rotates on the waste slide base (15) driven by the external air circuit. Under the continuous pressure of the external air circuit, the pressing surface of the body contacts the lower end of DE, so that the nitrogen spring of the rotating wedge return drive device (14) The spring compression stroke reaches its maximum; after punching, in step S5, pressure is maintained on sections BC and DE of the workpiece (1). The pressure of the upper die nitrogen spring (8) is greater than the pressure of the suspension block nitrogen spring (16). The pressure maintenance time of section DE is equal to the compression stroke release time of the upper die pressure feeder (7). The pressure maintenance time of section BC is achieved using a delayed nitrogen spring device (10); in step S1, the groove-shaped contour block (6) in the three-moving wedge is filled into the workpiece (1); in step S4, after the material is pressed into place on each profile, the upper die pressure feeder (7) is in the upper die (9) Under the action of the pressure plate (12) on the groove-shaped contour block (6) presses down continuously. Under the action of the pressure plate nitrogen spring (21), the punch on the punch holder (11) contacts the workpiece (1). The upper die pressure plate (7) continues to press down. Since the pressure of the upper die nitrogen spring (8) is greater than the pressure of the suspension block nitrogen spring (16), the groove-shaped contour block (6) performs punching work as a whole. The punching ends when the lower suspension block nitrogen spring (16) is compressed to the bottom. It also includes the mold opening and part removal in step S6.Step S6: After the springback holding pressure is completed, the mold is opened. The return stroke of the upper mold nitrogen spring (8) and the suspension block nitrogen spring (16) causes the groove-shaped contour block (6) to float to the pressing position. The delayed nitrogen spring device (10) returns to the initial state under the drive of the external air path. The rotating wedge body (13) returns to the initial position under the pressure release of the rotating wedge return drive device (14). The rotating wedge return drive device (14) includes a return stroke. The nitrogen spring (18), the limiting baffle (19), and the return pressure plate (20) are used. The return stroke is achieved by the return pressure plate (20), and the limiting baffle (19) provides limiting constraints. When the upper mold (9) continues to retract, the three-moving wedge insert (4) is pulled back by the longitudinal cylinder (22), driving the three-moving wedge drive seat (3) and the groove-shaped contour block (6) to retract according to the predetermined reciprocating stroke until the M and P points of the two guide plate inclined surfaces return to their initial positions.

2. The springback control method for the inner punching die of aluminum alloy automotive body panels according to claim 1, characterized in that: In step S6, the finished product is picked up by the robotic arm end effector.

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