Closed torsion beam trailing arm stamping and welding process

Abstract

The present invention relates to the technical field of automotive part forming, and specifically discloses a stamping and welding process for a closed torsion beam longitudinal arm. S1. Drawing: Form a partial product profile of the longitudinal arm by means of stamping and drawing; S2. Trimming: Remove the redundant material, and at the same time stamp an oblique angle on the edge of the sheet metal; S3. Stamping and flanging; S4. Final stamping forming: Use a final forming die to directly stamp and close the free end of the product with a U-shaped cross-section. The final forming die includes an upper die and a lower die. The lower die is in concave-convex fit with the drawing part of the product. A cavity matching the shape of the designed product is provided on the upper die. Guide inclined surfaces are provided on both sides of the cross-section of the cavity of the upper die. During the die closing process of the final forming die, the oblique angle at the free end of the product automatically moves along the edge of the cavity of the upper die until the free end is closed at the top of the cavity; S5. Welding: Weld at the closed position of the product. This solution is used to solve the problem of low forming efficiency of the longitudinal arm existing in the current method of forming the longitudinal arm by means of tube rolling.

Description

Technical Field

[0001] The present invention relates to the technical field of automotive component forming, and particularly to a stamping and welding process for the longitudinal arm of a closed torsion beam. Background Art

[0002] Automotive torsion beams are widely popular because of their simple structure, convenient adjustment and maintenance, simple manufacturing, and the large space they create for the rear row and trunk of the vehicle. Among current automotive torsion beams, the most mainstream one is the closed torsion beam with a closed cross-section on the crossbeam.

[0003] The closed torsion beam includes a crossbeam and longitudinal arms on both sides of the crossbeam. With the increasingly mature manufacturing process of the crossbeam, closed longitudinal arms have gradually started to be promoted. Existing closed longitudinal arms have two forms: one is to weld the left and right stamped parts of the longitudinal arm into a closed structure after stamping and forming (fast forming, but generating a lot of waste); the other is to form the pipe by rolling and closing after the sheet is drawn (the material is formed by drawing, without setting too much stamping allowance, so the utilization rate of the sheet is improved). After the pipe is formed, the closing position of the longitudinal arm is closed by welding. However, in the prior art, for the rolling and closing forming of the longitudinal arm, it needs to be gradually stamped and shaped by multiple molds after drawing. For example, it is first stamped and drawn into a U shape, and then the two free ends of the U shape are gradually rolled inward by multiple molds to make the shape of the formed sheet meet the design requirements. This forming method uses a lot of molds, greatly reducing the forming efficiency of the longitudinal arm. Summary of the Invention

[0004] The present invention aims to provide a stamping and welding process for the longitudinal arm of a closed torsion beam to solve the problem of low forming efficiency of the longitudinal arm existing in the current rolling and forming method.

[0005] To achieve the above object, the present invention adopts the following technical solutions:

[0006] A stamping and welding process for the longitudinal arm of a closed torsion beam, comprising the following process steps:

[0007] S1. Drawing: Form part of the product profile of the longitudinal arm by stamping and drawing. At this time, the cross-section of the drawn part of the product is U-shaped;

[0008] S2. Trimming: Stamp and trim the sheet completed in S1 to remove the excess material. At the same time, chamfers are stamped on the sheet edge during trimming;

[0009] S3. Stamping and flanging: Stamp and flange the non-drawn part of the sheet. At this time, the cross-section of the product is U-shaped;

[0010] S4. Final forming by stamping: The free end of the U-shaped cross-section product is directly stamped and closed by the final forming die. The final forming die includes an upper die and a lower die. The lower die is matched with the drawing part of the product in a concave and convex manner. The upper die is provided with a cavity that matches the shape of the designed product. The two sides of the cross section of the cavity of the upper die are provided with guiding inclined surfaces. When the final forming die is closed, the bevel of the free end of the product automatically moves along the edge of the cavity of the upper die during the process of pressing the upper die downward until the two free ends of the product are closed at the top of the cavity.

[0011] S5. Welding: Welding is performed at the closed position of the product.

[0012] The principle and advantage of this scheme are: when adopting this scheme, the forming of part of the product surface is completed through one stamping and drawing, and the remaining part is trimmed to remove excess sheet material, and then the remaining surface of the product is directly formed by the final forming mold after stamping and flanging. Before final forming, there is no need to gradually shape the free end of the product. Instead, the bevel of the product's own side line guides the entire free end of the product to automatically move along the cavity surface of the upper mold. Even if the free end of the product rebounds after stamping, the free end side line of the product will move closer to the cavity after contacting the guiding inclined surface, and finally stick to the cavity surface to complete the final forming. It can be seen that compared with the existing technology, this scheme does not need to set up multiple molds to perform multiple shaping and curling of the free end of the product, which greatly reduces the forming efficiency.

[0013] Preferably, as an improvement, during the drawing in step S1, two longitudinal arms are drawn simultaneously on a sheet material, and the two longitudinal arms are structurally symmetrical during the drawing, and step S6 is also included, in which the welded product is cut into two longitudinal arms.

[0014] Beneficial effects: When this solution is adopted, the two longitudinal arms required for the torsion beam are directly formed each time, which further improves the production efficiency of the longitudinal arms. In addition, the two longitudinal arms on the same torsion beam are formed simultaneously using the same mold, which ensures the quality consistency of the two longitudinal arms under the same torsion beam, which is beneficial to improving the quality of the torsion beam.

[0015] Preferably, as an improvement, the longitudinal arm comprises a sleeve overlapping section, an intermediate variable cross-section section and an end fixed cross-section section, the maximum cross-sectional area of ​​the intermediate variable cross-section section> the cross-sectional area of ​​the end fixed cross-section section> the maximum cross-sectional area of ​​the sleeve overlapping section; the end fixed cross-sectional sections of the two longitudinal arms formed by drawing are connected into one, and when the product is cut after welding, the two longitudinal arms are cut out by cutting the end fixed cross-sectional sections.

[0016] Beneficial effects: When adopting this solution, while ensuring the simultaneous production of two longitudinal arms to improve production efficiency, through the shape design of the longitudinal arms, the stamping-final-formed product is in the shape of a bow. The formed product has the smallest shape dimensions at both ends (both ends are sleeve overlapping sections), and the shape dimensions in the middle are the second smallest (two end fixed cross-section sections), that is, both middle variable cross-section sections are located between the two small dimensions. This ensures that the deformation of the middle variable cross-section section after stamping is restricted by the small-size shapes at both ends. Since the longitudinal arm ends have small dimensions and basically no variable cross-section, their shape dimensions are very stable after forming. Therefore, the dimensions and precision of the middle variable cross-section section, whose original shape structure is difficult to control, are greatly improved, ensuring the dimensional precision and shape precision of the overall product after stamping. In addition, because the deformation of the middle variable cross-section section of the longitudinal arm is restricted and not easily deformed, the design requirements for the welding auxiliary tooling during subsequent welding are also reduced, which is beneficial to the simplification of the welding auxiliary tooling.

[0017] Preferably, as an improvement, in step S1, during drawing, a drawing protrusion is drawn on the sheet, and the drawing protrusion is located on both sides in the width direction of the end fixed cross-section section.

[0018] Beneficial effects: When adopting this solution, since the drawn product is in the shape of a bow in the axial direction of the longitudinal arm, and the end fixed cross-section sections with smaller dimensions during the forming of the two longitudinal arms are located in the middle of the drawing, and the middle variable cross-section sections with gradually increasing cross-sections extend from the middle of the drawing to both ends, it is easy for the end fixed cross-section sections after drawing to wrinkle. By setting the drawing protrusion in this solution, during the drawing process, the material flow during the stretching of the sheet is restricted by the drawing protrusion, hindering the stretching speed of the end fixed cross-section section, and ensuring the uniform stretching of the end fixed cross-section section without wrinkling.

[0019] Preferably, as an improvement, in step S2, the size compensation is performed on the trimming edge line according to the change of the closing gap after final forming in step S4. For the position with a large closing gap, the perimeter of the corresponding cross-section is increased, while for the position with a small closing gap, the perimeter of the corresponding cross-section is decreased.

[0020] Beneficial effects: Since the size of the closing gap at the closing position has a great influence on the welding quality, a uniform and qualified-width gap is the basis for ensuring welding quality. By performing the edge compensation during trimming in this solution, the closing gap after final forming meets the welding requirements, and there is no need to shape the product after final forming, reducing the production process and being beneficial to reducing staff and improving efficiency.

[0021] Preferably, as an improvement, in step S5, positioning pieces are inserted into the interior of the longitudinal arm from both ends of the product, the closing gap of the product is located at the top, and a first clamping block is arranged at the intersection transition position of the sleeve overlapping section and the middle variable section of the longitudinal arm, and the first clamping block is opposite to the positioning piece; a second clamping block is arranged in the middle of the product, and both the first clamping block and the second clamping block clamp the product from top to bottom.

[0022] Beneficial effect: When this solution is adopted, the position of the product is limited by inserting the positioning pieces at both ends into the interior of the product. At the same time, the deformation caused by the influence of welding heat after welding is limited by the setting of the first clamping block and the second clamping block, thereby ensuring the welding quality and the dimensional accuracy and shape accuracy of the product after welding.

[0023] Preferably, as an improvement, the length of the end fixed-section segment drawn in step S1 is at least 5 mm longer than the design size of the longitudinal arm, forming a processing allowance in the middle. In step S5, when welding, spot welding or welding of a small section is first performed in the middle of the connection position of the two longitudinal arms, and the length of the welding small section is less than the length of the processing allowance, and then continuous welding is performed starting from the overlapping sections of the sleeve.

[0024] Beneficial effect: This solution designs the processing allowance of the product during drawing, so that after the two longitudinal arms are continuously welded, the processing allowance at the butt ends of the two longitudinal arms can be cut off. The cut processing allowance portion is exactly the portion where the two longitudinal arms are connected during welding. By directly cutting off the portion that cannot be continuously welded, a continuous and uniform weld is ensured on a single longitudinal arm, and the requirements for welding are reduced.

[0025] Preferably, as an improvement, the longitudinal arm is cut by laser cutting in step S6, and a shock-absorbing mounting hole is cut in the middle variable-section section of each longitudinal arm; and step S7-welding a shock-absorbing mounting bracket is also included, and the shock-absorbing mounting bracket is fixedly mounted in the shock-absorbing mounting hole, and the shock-absorbing mounting bracket passes through the longitudinal arm.

[0026] Beneficial effects: This solution welds a shock-absorbing mounting bracket that passes through the longitudinal arm, so that the shock-absorbing mounting bracket not only facilitates the installation of the shock absorber, but also increases the connection strength between the shock-absorbing mounting bracket and the longitudinal arm. In addition, the setting of the shock-absorbing mounting bracket is equivalent to processing reinforcing ribs on the tubular longitudinal arm, which greatly improves the rigidity and strength of the longitudinal arm.

[0027] Preferably, as an improvement, the method further comprises welding a reinforcing plate within the fixed cross-section section at the end of the longitudinal arm after step S7 is completed.

[0028] Beneficial effects: Through the arrangement of the reinforcing plate, the strength and lateral stiffness of the longitudinal arm are further improved. Especially after installing the wheel hub bracket between the shock-absorbing mounting plate and the reinforcing plate, both the wheel hub bracket and the spring tray bracket are direct force transmission points after the automobile wheel is stressed, and the force from the wheel will act on the longitudinal arm. The arrangement of the reinforcing plate in this solution in cooperation with the shock-absorbing mounting plate makes the longitudinal arm have greater strength at the positions where the wheel hub bracket and the spring tray bracket are installed, which is beneficial to extending the service life of the torsion beam. Brief Description of the Drawings

[0029] Figure 1 It is a schematic structural view of the formed torsion beam longitudinal arm of the present invention after welding the sleeve, the spring tray bracket and the wheel hub bracket.

[0030] Figure 2 It is Figure 1 the top view.

[0031] Figure 3 It is Figure 1 the cross-sectional view.

[0032] Figure 4 It is a schematic structural view of the longitudinal arm of the present invention after being connected to the cross beam.

[0033] Figure 5 It is the process flow chart of the present invention.

[0034] Figure 6 It is a schematic structural view of the final forming die of process step S4 of the present invention.

[0035] Figure 7 It is a schematic layout view of the positions of the positioning member, the first pressing block and the second pressing block during welding of the present invention.

[0036] Figure 8 It is a schematic view of the positional relationship between the pressing block, the limiting block and the cross-section of the longitudinal arm in the embodiment of the present invention. Detailed Description of the Invention

[0037] The following is a further detailed description through specific embodiments:

[0038] The reference numerals in the accompanying drawings of the specification include: sleeve overlapping section 1, intermediate variable cross-section section 2, end fixed cross-section section 3, shock-absorbing mounting hole 20, shock-absorbing mounting plate 4, and reinforcing plate 5.

[0039] The embodiment is basically as shown in the attached Figures 1 to 8 figure, the stamping and welding process of the closed torsion beam longitudinal arm, the structure of the formed longitudinal arm is as shown in Figures 1 to 3 the figure, and the structure of the torsion beam after the longitudinal arm is connected to the cross beam is as shown in Figure 4As shown in the figure, the longitudinal arm includes a sleeve overlapping section 1, an intermediate variable cross-section section 2, and an end fixed cross-section section 3. The maximum cross-sectional area of the intermediate variable cross-section section 2 > the cross-sectional area of the end fixed cross-section section 3 > the maximum cross-sectional area of the sleeve overlapping section 1. The sheet material used for the formed longitudinal arm in this embodiment is high-strength steel with a material thickness of 2.2 - 3.2 mm, such as CP800 steel.

[0040] Combined with Figures 5 to 8 , the forming process of the longitudinal arm is as follows:

[0041] S1. Drawing: The profile on the side of the longitudinal arm close to the crossbeam is formed by stamping and drawing. At this time, the cross-section of the drawn part of the longitudinal arm is U-shaped; in this process, two longitudinal arms are drawn simultaneously on a sheet of material. When drawing, the structures of the two longitudinal arms are symmetrical, and the end fixed cross-section sections 3 of the two longitudinal arms are connected into one body, that is, a conjoined longitudinal arm is formed; in order to prevent wrinkling from occurring in the end positioning cross-section section with a smaller cross-sectional size of the conjoined longitudinal arm, drawing protrusions are simultaneously drawn on the sheet material. The drawing protrusions are located on both sides in the width direction of the end fixed cross-section section; the length of the drawn end fixed cross-section section 3 is at least 5 mm longer than the designed size of the longitudinal arm, forming a machining allowance in the middle of the conjoined longitudinal arm; the drawn part of the conjoined longitudinal arm is bow-shaped in the length direction.

[0042] S2. Trimming: The sheet material that has completed S1 is trimmed by stamping to remove the excess material. At the same time, chamfers are stamped on the edge of the sheet material during trimming; in this step, dimensional compensation is performed on the trimming edge according to the change in the closing gap after the final forming in step S4. The perimeter of the corresponding cross-section is increased at the position where the closing gap is large, while the perimeter of the corresponding cross-section is reduced at the position where the gap is small or there is overlap, ensuring that the width of the closing gap is uniform after subsequent closing.

[0043] S3. Stamping flanging: The non-drawn part of the sheet material is stamped and flanged. At this time, the cross-section of the product is U-shaped.

[0044] S4. Final stamping forming: The free end of the U-shaped cross-section product is directly stamped and closed using a final forming die. Combined with Figure 6 , the final forming die includes an upper die and a lower die. The lower die is in concave-convex fit with the drawn part of the longitudinal arm. The upper die is provided with a cavity that matches the shape of the designed conjoined longitudinal arm. Guide inclined surfaces are provided on both sides of the cross-section of the cavity of the upper die. When the final forming die is closed, during the process of the upper die pressing down, the chamfers at the free ends of the conjoined longitudinal arms automatically move along the edge of the cavity of the upper die until the two free ends of the longitudinal arm are closed at the top of the cavity. The closing gap presents a V-shaped groove due to the chamfer fit, facilitating subsequent welding; the formed conjoined longitudinal arm is bow-shaped.

[0045] S5. Welding: Welding is performed at the closing position of the product; specifically during welding, combined with Figure 7 and Figure 8, before welding, first insert positioning members into the interior of the longitudinal arm from both ends of the product, such that the closing gap of the product is located at the topmost part. Set a first pressing block at the intersection transition position between the sleeve overlapping section 1 of the longitudinal arm and the middle variable cross-section section, with the first pressing block facing the positioning member; set a second pressing block in the middle of the product. Both the first pressing block and the second pressing block press the product from top to bottom. In this embodiment, the power for driving the first pressing block and the second pressing block to press the longitudinal arm can come from a lever cylinder with a lever body, so as to facilitate the two pressing blocks to approach the product in a swinging manner and press the product, facilitating the removal and insertion of the product before and after welding. In addition, in order to ensure that the deformation of the product during welding does not exceed the design requirements, limit blocks are provided on both sides in the width direction of the product.

[0046] During welding, first perform spot welding or weld a small section in the middle of the connection position of the two longitudinal arms. The length of the welded small section is less than the length of the machining allowance, and then start continuous welding from the sleeve overlapping section 1 respectively.

[0047] S6. Cutting: Laser cut the welded connected longitudinal arms. First, cut off the excess material (including the shock absorber mounting holes 20, end face cutting for sleeve mounting, and other process holes, positioning holes, etc.) on each longitudinal arm of the connected longitudinal arms, and then cut the connected longitudinal arms from the middle to obtain two separate longitudinal arm finished products with continuous weld seams.

[0048] S7. Weld the shock absorber mounting bracket. The shock absorber mounting bracket is fixedly sleeved in the shock absorber mounting hole 20 by welding, and the shock absorber mounting bracket penetrates the longitudinal arm; weld a reinforcing plate 5 in the end constant cross-section section 3 of the longitudinal arm. The length of the longitudinal arm between the reinforcing plate 5 and the shock absorber mounting plate 4 can accommodate the wheel hub bracket; then weld the wheel hub bracket.

[0049] When producing the longitudinal arm using the above process steps, not only are two longitudinal arms processed in each forming, but also the steps of each forming are simple. One drawing, one stamping flanging, and one final stamping forming complete the curling forming of the longitudinal arm, and the fixation of the two longitudinal arms before welding is completed through one fixture tooling positioning. The entire process has few processes, short time consumption, and simple molds, greatly improving the production efficiency. At the same time, it also cooperates with the special shape structure design of the longitudinal arm, resulting in high-quality formed products.

[0050] Installing the shock absorber mounting plate 4 and the reinforcing plate 5 on the longitudinal arm is equivalent to processing two stiffening ribs on the tubular longitudinal arm, greatly improving the stiffness and strength of the longitudinal arm, which is beneficial to extending the service life of the torsion beam.

[0051] The above are only embodiments of the present invention, and common general technical solutions and / or characteristics in the solutions are not described in detail herein. It should be noted that for those skilled in the art, without departing from the technical solutions of the present invention, several deformations and improvements can be made, which should also be regarded as the protection scope of the present invention, and these will not affect the implementation effect of the present invention and the practicality of the patent. The protection scope claimed in this application shall be subject to the content of its claims, and the specific implementation manners and the like recorded in the specification can be used to interpret the content of the claims.

Claims

1. Closed torsion beam longitudinal arm stamping and welding process, characterized in that, It includes the following technological steps: S1. Drawing: Form part of the product profile of the longitudinal arm in a stamping and drawing manner. At this time, the cross-section of the drawn part of the product is U-shaped; S2. Trimming: Stamp and trim the sheet metal that has completed S1 to remove excess material. At the same time, bevel angles are stamped on the edge of the sheet metal during trimming; S3. Stamping and flanging: Stamp and flange the non-drawn part of the sheet metal. At this time, the cross-section of the product is U-shaped; S4. Final stamping forming: Use a final forming die to directly stamp and close the free ends of the product with a U-shaped cross-section. The final forming die includes an upper die and a lower die. The lower die is in concave-convex fit with the drawn part of the product. The upper die is provided with a cavity that matches the shape of the designed product. Guiding inclined surfaces are provided on both sides of the cross-section of the cavity of the upper die. When the final forming die is closing the mold, during the process of the upper die pressing downwards, the bevel angles at the free ends of the product automatically move along the edge of the cavity of the upper die until the two free ends of the product are closed at the top of the cavity; S5. Welding: Weld at the closed position of the product.

2. The closed torsion beam trailing arm stamping and welding process according to claim 1, characterized in that: During the drawing in step S1, two longitudinal arms are drawn simultaneously on a single sheet metal. The structures of the two longitudinal arms are symmetrical during drawing. It also includes step S6 of cutting the welded product into two longitudinal arms.

3. The closed torsion beam trailing arm stamping and welding process according to claim 2, characterized in that: The longitudinal arm includes a sleeve overlapping section, an intermediate variable cross-section section, and an end fixed cross-section section. The maximum cross-sectional area of the intermediate variable cross-section section > the cross-sectional area of the end fixed cross-section section > the maximum cross-sectional area of the sleeve overlapping section; The end fixed cross-section sections of the two longitudinally drawn arms are connected into one body. When cutting the product after welding, two longitudinal arms are cut out through the end fixed cross-section section.

4. The closed torsion beam trailing arm stamping and welding process according to claim 3, characterized in that: In step S1, during drawing, drawing protrusions are drawn on the sheet metal. The drawing protrusions are located on both sides in the width direction of the end fixed cross-section section.

5. The enclosed torsion beam trailing arm stamping and welding process according to claim 3, characterized in that: In step S2, dimensional compensation is performed on the trimming edge line according to the change in the closing gap after final forming in step S4. The perimeter of the corresponding cross-section is increased at the position where the closing gap is large, while the perimeter of the corresponding cross-section is decreased at the position where the closing gap is small.

6. The closed torsion beam trailing arm stamping and welding process according to claim 5, characterized in that: In step S5, positioning members are inserted into the longitudinal arms from the two ends of the product. The closing gap of the product is located at the topmost part. A first pressing block is arranged at the intersection transition position between the sleeve overlapping section and the middle variable cross-section section of the longitudinal arm. The first pressing block is opposite to the positioning member; A second pressing block is arranged in the middle of the product. Both the first pressing block and the second pressing block press the product from top to bottom.

7. The closed torsion beam trailing arm stamping and welding process according to claim 6, characterized in that: The length of the end fixed cross-section section drawn in step S1 is at least 5 mm longer than the designed size of the longitudinal arm, forming a machining allowance in the middle. In step S5, during welding, first perform spot welding or weld a small section at the middle of the connection position of the two longitudinal arms. The length of the welded small section is less than the length of the machining allowance, and then continuous welding is carried out starting from the sleeve overlapping section respectively.

8. The closed torsion beam trailing arm stamping and welding process according to claim 7, characterized in that: In step S6, the longitudinal arms are cut by a laser cutting method, and shock-absorbing mounting holes are cut out in the intermediate variable cross-section section of each longitudinal arm; It also includes step S7 - welding a shock-absorbing mounting bracket. The shock-absorbing mounting bracket is fixedly sleeved in the shock-absorbing mounting hole, and the shock-absorbing mounting bracket penetrates through the longitudinal arm.

9. The closed torsion beam trailing arm stamping and welding process according to claim 8, characterized in that: It also includes welding a reinforcing plate in the end fixed cross-section section of the longitudinal arm after step S7 is completed.

Images