Stamping part edge controllable double-face rounding arc forming structure and method

Abstract

The invention discloses a stamping part edge controllable double-face rounding arc forming structure and method. The stamping part edge controllable double-face rounding arc forming structure comprises an upper die assembly and a lower die assembly. The upper die assembly comprises an upper die base, a punching male die, an upper arc forming male die and a shaping upper die, wherein the punching male die, the upper arc forming male die and the shaping upper die are sequentially and fixedly installed on the lower surface of the upper die base in the feeding direction. The lower die assembly comprises a lower die base, a punching female die, a shaping lower die and a lower arc forming male die, wherein the punching female die, the shaping lower die and the lower arc forming male die are sequentially and fixedly installed on the upper surface of the lower die base in the feeding direction, and the punching male die and the punching female die form a first station. The upper arc forming male die and the shaping lower die form a second station; the upper shaping die and the lower arc forming male die form a third station; by separating the rounding stations on the upper side and the lower side, the size precision and the surface smoothness of edge fillets are remarkably improved, and C corners or micro burrs generated by a traditional single-time leveling process are effectively eliminated.

Description

Technical Field

[0001] This invention relates to the field of controllable double-sided rounded arc forming of stamped parts. More specifically, this invention relates to a structure and method for controllable double-sided rounded arc forming of stamped parts. Background Technology

[0002] Sharp edges, or burrs, on the edges of stamped automotive parts can have a series of serious impacts on surrounding flexible components such as rubber parts, fabrics, and wiring harnesses after assembly. The core risk is long-term wear and cuts, ultimately leading to functional failure or safety accidents. Controlling sharp edges on stamped parts requires prevention at the source of stamping production, treatment during assembly, and protection after assembly.

[0003] Stamping source control: By controlling the blanking clearance and maintaining a sharp cutting edge, ensuring a uniform and appropriate gap between the stamping punch and die, low-burr products that meet standard values ​​can be produced. Sharp edges may still exist, but regular grinding or replacement of worn cutting edges is required, and the die needs frequent maintenance. This is the most ideal and economical method when sharp edges are not a primary requirement.

[0004] Pre-assembly treatment: Rounding the edges of sharp edges on parts by manual or automatic grinding before assembly can significantly improve safety and durability. While the rounding effect is good, it is costly and time-consuming. When rubber parts pass near sheet metal holes or sharp edges, protective sleeves, corrugated pipes, abrasion-resistant tape, or special brackets should be designed and used for physical isolation. Isolating and protecting areas that come into contact with personnel or wiring harnesses reduces the risk of wear. This method is expensive.

[0005] Assembly process protection: During the product design phase, design isolation and protective structures for sharp edges of stamped parts. When wire harnesses or rubber parts pass near sheet metal holes or sharp edges, design and use protective sleeves, corrugated pipes, wear-resistant tape, or special brackets for physical isolation. Isolate and protect areas that come into contact with personnel or parts that come into contact with wire harnesses to reduce the risk of wear. This method is costly.

[0006] Traditional die structures that control burr height or remove burrs at the stamping source still produce stamped parts with C-shaped beveled edges. These newly generated C-shaped edges can still scratch rubber, wire harnesses, and other environmentally friendly components. Therefore, the quality requirement for stamped parts edges needs to be changed from "burr-free" to "fully rounded corners." Summary of the Invention

[0007] To achieve these objectives and other advantages according to the present invention, a preferred embodiment of the present invention provides a controllable double-sided rounded arc forming structure for stamped parts, comprising an upper die assembly and a lower die assembly; the upper die assembly includes an upper die base, and a punching punch, an upper arc forming punch, and a shaping upper die, which are sequentially fixedly mounted on the lower surface of the upper die base along the feeding direction; the lower die assembly includes a lower die base, and a punching die, a shaping lower die, and a lower arc forming punch, which are sequentially fixedly mounted on the upper surface of the lower die base along the feeding direction; wherein, the punching punch and the punching die constitute a first station for punching or trimming the part; the upper arc forming punch and the shaping lower die constitute a second station for rounding the upper surface edge of the part; the shaping upper die and the lower arc forming punch constitute a third station for rounding the lower surface edge of the part. The three workstations are fixed in the horizontal direction. The part is driven by an external feeder and passes through the first workstation, the second workstation, and the third workstation in a step-by-step manner along the feeding direction.

[0008] Preferably, it also includes a pressure plate, which is disposed below the upper die base and arranged around the punching punch, the upper arc forming punch and the shaping upper die, for pressing the part during the stamping process.

[0009] Preferably, the pressure plate is provided with a positioning pin, which is adapted to the pre-punched hole on the part for precise positioning.

[0010] Preferably, it also includes a lifting plate, which is located above the lower mold base and connected to the lower mold base through a lower mold pressure source; in the mold open state, the lifting plate lifts the part upward, causing it to leave the lower mold working surface, so that the feeder can push the part forward one step.

[0011] Preferably, the lower end face of the upper arc forming punch is a convex curved surface, and the upper end face of the lower shaping die is a matching concave arc surface; the lower end face of the upper shaping die is a plane or a slightly concave surface, and the upper end face of the lower arc forming punch is a convex curved surface, which is used to cooperate with the upper shaping die to complete the rounding and shaping of the lower edge.

[0012] Preferably, the total height of the first arc forming gap and the second arc forming gap in the vertical direction is equal to the material thickness of the part.

[0013] Preferably, the sum of the vertical gap between the upper arc forming punch and the lower forming die and the vertical gap between the upper forming die and the lower arc forming punch is equal to the material thickness of the part.

[0014] A preferred embodiment of the present invention provides a method for forming a double-sided rounded arc at the edge of a stamped part, employing the aforementioned double-sided rounded arc forming structure at the edge of a stamped part. The method includes the following steps: S1. The stamping part to be processed is fed into the forming structure along the feeding direction by an external feeder; at the first station, the stamping part is punched or trimmed by a punching punch and a punching die, and pre-punched holes are formed for subsequent positioning. S2. After completing S1, raise the pressure plate to release the stamping part, and move it forward one step to the second station under the drive of the feeder; then, the pressure plate lowers to press the stamping part. In this state, the upper arc forming punch and the lower forming die cooperate to perform single-sided rounded corner plastic forming on the upper surface edge of the stamping part to form the upper R-corner. S3. After completing S2, the pressure plate is raised again to release the constraint on the stamping part, so that it moves forward one step to the third station under the drive of the feeder; then, the pressure plate is lowered to press the stamping part; in this state, the upper forming die and the lower arc forming punch cooperate to apply reverse pressure to the lower surface edge of the stamping part, to perform lower rounded corner plastic forming and simultaneously flatten the burrs to form the lower R-corner.

[0015] Preferably, in step S2, when the upper surface edge of the stamped part is plastically formed by rounding the corners on one side at the second station, the upper arc forming punch is controlled to move at a first downward speed. The first downward speed refers to the speed used by the punch during the downward process from the first contact with the upper surface edge of the stamped part to the closing position with the lower forming die to complete the forming, and the process takes no less than 0.3 seconds. In step S3, when the lower surface edge of the stamped part is rounded at the third station, the upper forming die is controlled to move at a second downward speed. The second downward speed refers to the speed used by the upper die from the first contact with the lower surface edge of the stamped part to the complete closure with the lower arc forming punch during the downward process, and the process takes no more than 0.15 seconds. The second downward speed is significantly higher than the first downward speed, and the forming end face of the upper arc forming punch is provided with a micro-ridge extending along the feeding direction, the height of which is 0.02 to 0.08 mm.

[0016] Preferably, in step S3, the upper forming die is controlled to descend at a high speed at a second downward speed, and within a range of 1.0 mm to 0.5 mm from the top of the lower arc forming punch, the downward speed is reduced to 30% to 50% of the second downward speed, and then quickly closed after 0.02 to 0.05 seconds, so as to generate controllable micro-impact, enhance burr crushing and suppress springback.

[0017] The present invention has at least the following beneficial effects: by separating the upper and lower rounded corners, the present invention significantly improves the dimensional accuracy and surface finish of the edge rounded corners, and effectively eliminates the C-corners or microburrs produced by the traditional single-step flattening process.

[0018] Other advantages, objectives and features of the present invention will become apparent in part from the following description, and in part from those skilled in the art through study and practice of the invention. Attached Figure Description

[0019] Figure 1 This is a three-dimensional schematic diagram of the controllable double-sided rounded arc forming structure of the stamped part in this invention.

[0020] Figure 2 This is a cross-sectional schematic diagram of the controllable double-sided rounded arc forming structure of the stamped part in this invention. Detailed Implementation

[0021] The present invention will now be described in further detail with reference to the accompanying drawings, so that those skilled in the art can implement it based on the description.

[0022] The following description is intended to disclose the present invention and enable those skilled in the art to implement it. The preferred embodiments described below are merely examples, and other obvious modifications will occur to those skilled in the art. The basic principles of the invention defined in the following description can be applied to other embodiments, modifications, improvements, equivalents, and other technical solutions that do not depart from the spirit and scope of the invention.

[0023] Those skilled in the art should understand that, in the disclosure of this invention, the terms "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, the above terms should not be construed as limiting this invention.

[0024] It is understood that the term "a" should be understood as "at least one" or "one or more", that is, in one embodiment, the number of an element can be one, while in another embodiment, the number of the element can be multiple, and the term "a" should not be understood as a limitation on the number.

[0025] like Figure 1-2As shown, a preferred embodiment of the present invention provides a controllable double-sided rounded arc forming structure for stamped parts, including an upper die assembly and a lower die assembly; the upper die assembly includes an upper die base 13, and a punching punch 4, an upper arc forming punch 6, and a shaping upper die 8, which are sequentially fixedly installed on the lower surface of the upper die base 13 along the feeding direction; the lower die assembly includes a lower die base 11, and a punching die 5, a shaping lower die 7, and a lower arc forming punch 9, which are sequentially fixedly installed on the upper surface of the lower die base 11 along the feeding direction; wherein, the punching punch 4 and the punching die 5 constitute a first station for punching or trimming the part 2; the upper arc forming punch 6 and the shaping lower die 7 constitute a second station for rounding the upper surface edge of the part 2; the shaping upper die 8 and the lower arc forming punch 9 constitute a third station for rounding the lower surface edge of the part 2. The three workstations are fixed in the horizontal direction. The part 2 is driven by an external feeder and passes through the first workstation, the second workstation and the third workstation in a step-by-step manner along the feeding direction.

[0026] At the start of the operation, part 2 is located at the mold entrance. In the first stamping cycle, the external feeder pushes it one step to the first station, and the punching punch 4 moves downward to complete punching or trimming with the punching die 5, forming a positioning reference hole. After stamping, the slide returns, the lifting plate 3 lifts the part, and the feeder pushes it forward one step, moving the punched area to the second station. In the second stamping cycle, the upper arc forming punch 6 moves downward to close with the shaping lower die 7, rounding the upper surface edge of part 2. After completion, the mold opens again, the material is lifted, and the feeder moves the part forward one step to the third station. In the third stamping cycle, the shaping upper die 8 moves downward to close with the lower arc forming punch 9, applying reverse pressure to the lower surface edge of part 2, completing the lower rounding and overall shaping. Thus, part 2 has passed through three stations in sequence, completing all processing in three independent stamping cycles. Throughout the process, the three stations are fixed in the horizontal direction and only move vertically with the press. The same part 2 is driven by an external feeder and moves forward one step at a time along the feeding direction after each mold opening, passing through the first station, the second station and the third station in turn to achieve controllable rounding of the edge on both sides.

[0027] The present invention also provides the following technical solution, which further includes a pressure plate 1, wherein the pressure plate 1 is disposed below the upper die base 13 and is arranged around the punching punch 4, the upper arc forming punch 6 and the shaping upper die 8, for pressing the part 2 during the stamping process.

[0028] During operation, as the press slide begins its downward descent, the pressure plate 1, under the pressure of the upper die, first contacts the surface of part 2 and applies pre-pressure, firmly fixing part 2 to the working surface of the lower die. Subsequently, the punching punch 4, the upper arc forming punch 6, and the shaping upper die 8 continue to descend, each performing the forming action at its respective station. Because part 2 has been pressed tightly, it will not shift under lateral extrusion force, especially the lateral component of the metal flow during rounded corner forming, thus ensuring the accuracy of the R-corner position and the surface finish.

[0029] The present invention also provides the following technical solution: the pressure plate 1 is provided with a positioning pin, which is used to insert into the pre-punched hole on the part 2 in the initial stage of mold closing to achieve precise positioning.

[0030] During operation, after the feeder pushes part 2 into place, the press slide begins to descend. Since the pressure plate 1 contacts part 2 first, the locating pin on it is then inserted into the pre-punched hole punched out from the first station on part 2. Once the locating pin is fully inserted, part 2 is locked in a precise position, and then the pressure plate 1 applies a clamping force, and the main punch begins to form.

[0031] The present invention also provides the following technical solution, which further includes a lifting plate 3, the lifting plate 3 being disposed above the lower mold base 11 and connected to the lower mold base 11 through the lower mold pressure source 10; in the mold open state, the lifting plate 3 lifts the part 2 upward, so that it is removed from the working surface of the lower mold, so that the feeder pushes the part 2 forward by one step.

[0032] During operation, after the press completes the stamping and begins its return stroke, the upper die assembly moves upward, releasing the downward pressure on the lifting plate 3. At this time, the lower die pressure source 10 provides an upward force, pushing the lifting plate 3 upward and lifting the part 2 as a whole by 2 to 5 millimeters, completely separating it from the top of the punching die 5, the shaping lower die 7, and the lower arc forming punch 9. In this state, the clamps of the external feeder can grip the front end of the part 2 without obstruction and push it forward one step. After pushing is completed, the press descends again, and the upper die assembly first contacts and presses the lifting plate 3, causing it to overcome the force of the lower die pressure source 10 and descend, eventually falling back to a position flush with the lower die base 11. Subsequently, each punch continues to descend to complete the stamping.

[0033] The present invention also provides the following technical solution: the lower end face of the upper arc forming punch 6 is a convex curved surface, and the upper end face of the shaping lower die 7 is a matching concave arc surface; the lower end face of the shaping upper die 8 is a plane or a slightly concave surface, and the upper end face of the lower arc forming punch 9 is a convex curved surface, which is used to cooperate with the shaping upper die 8 to complete the rounding and shaping of the lower edge.

[0034] During the operation, at the second station, as the upper arc forming punch 6 descends, its convex surface presses into the concave arc surface of the lower forming die 7, forcing the upper edge of part 2 into the gap between the curved surfaces. Under high pressure, the metal undergoes plastic flow along the curved surface, gradually conforming to the die surface and forming an R-angle consistent with the curvature of the convex surface. At the third station, the plane or slightly concave surface of the upper forming die 8 descends and closes with the convex surface of the lower arc forming punch 9, applying uniform pressure to the lower edge of part 2. Since the lower side was originally a punched burr surface, this reverse extrusion not only forms an R-angle but also flattens the burrs.

[0035] The present invention also provides the following technical solution, wherein the sum of the vertical gap between the upper arc forming punch 6 and the lower forming die 7 and the vertical gap between the upper forming die 8 and the lower arc forming punch 9 is equal to the material thickness of the part 2.

[0036] During operation, when part 2 is fed into the second station, its upper surface edge is located between the upper arc forming punch 6 and the lower forming die 7; when it is fed into the third station, its lower surface edge is located between the upper forming die 8 and the lower arc forming punch 9. Since the sum of the two gaps is exactly equal to the original material thickness of part 2, during mold closing and forming, the main body area of ​​the part is neither additionally compressed nor subjected to tensile stress in the thickness direction. Only the local edge area undergoes plastic flow under the guidance of the mold surface, thus forming a smooth R-corner. If the sum of the two gaps is greater than the material thickness, the metal cannot fully fill the mold cavity, resulting in an incomplete R-corner profile and surface depressions or steps. If the sum of the two gaps is less than the material thickness, excessive forming resistance will be generated during mold closing, which will not only significantly increase the load on the press, but may also cause local wrinkling of the part, material stacking, or even edge chipping, chipping, or permanent deformation of the mold working surface.

[0037] A preferred embodiment of the present invention provides a method for forming a double-sided rounded arc at the edge of a stamped part, employing the aforementioned double-sided rounded arc forming structure at the edge of a stamped part. The method includes the following steps: S1. The stamping part to be processed is fed into the forming structure along the feeding direction by an external feeder; at the first station, the stamping part is punched or trimmed by a punching punch and a punching die, and pre-punched holes are formed for subsequent positioning. S2. After completing S1, raise the pressure plate to release the stamping part, and move it forward one step to the second station under the drive of the feeder; then, the pressure plate lowers to press the stamping part. In this state, the upper arc forming punch and the lower forming die cooperate to perform single-sided rounded corner plastic forming on the upper surface edge of the stamping part to form the upper R-corner. S3. After completing S2, the pressure plate is raised again to release the constraint on the stamping part, so that it moves forward one step to the third station under the drive of the feeder; then, the pressure plate is lowered to press the stamping part; in this state, the upper forming die and the lower arc forming punch cooperate to apply reverse pressure to the lower surface edge of the stamping part, to perform lower rounded corner plastic forming and simultaneously flatten the burrs to form the lower R-corner.

[0038] Preferably, in step S2, when the upper surface edge of the stamped part is plastically formed by rounding the corners on one side at the second station, the upper arc forming punch is controlled to move at a first downward speed. The first downward speed refers to the speed used by the punch from the first contact with the upper surface edge of the stamped part to the closing position with the lower forming die to complete the forming process, and the process takes no less than 0.3 seconds. In step S3, when the lower surface edge of the stamped part is rounded at the third station, the upper forming die is controlled to move at a second downward speed. The second downward speed refers to the speed used by the upper die from the first contact with the lower surface edge of the stamped part to the complete closure with the lower arc forming punch during the downward process, and the process takes no more than 0.15 seconds. The second downward speed is significantly higher than the first downward speed, and the forming end face of the upper arc forming punch is provided with a micro-ridge extending along the feeding direction, the height of which is 0.02 to 0.08 mm.

[0039] In the above technical solution, firstly, the low-speed forming at the second station (first downward speed) provides sufficient plastic flow time for the metal material. Combined with the guiding effect of the micro-ridges, the contour of the upper R-corner is fuller and the dimensional accuracy is higher, effectively avoiding defects such as edge metal tearing and dents caused by excessive forming speed. The dimensional deviation of the upper R-corner can be controlled within 0.01mm. Secondly, the high-speed forming at the third station (second downward speed) uses instantaneous extrusion pressure to efficiently flatten burrs. Compared with the traditional low-speed flattening method, the burr flattening effect is more significant, which can completely eliminate the impact of micro-burrs on subsequent assembly. At the same time, high-speed forming effectively suppresses the springback phenomenon of the metal material, and the shape retention of the lower R-corner is better, making it less prone to deformation during subsequent storage and transportation. Finally, the micro-ridge structure on the upper arc forming punch provides clear guidance for the metal flow, avoiding disordered flow of the metal material during the forming process, further improving the surface finish of the stamped part's edge, and ensuring that the surface texture of the upper and lower R-corners is consistent, meeting the surface quality requirements of high-end automotive stamped parts.

[0040] The present invention also provides the following technical solution: In step S3, the upper forming die is controlled to descend at a high speed at a second downward speed, and within a range of 1.0 mm to 0.5 mm from the top of the arc forming punch at its end face, the downward speed is reduced to 30% to 50% of the second downward speed, and then closed rapidly after 0.02 to 0.05 seconds, so as to generate controllable micro-impact, enhance burr crushing and suppress springback.

[0041] In the above technical solution, the controllable micro-impact setting significantly enhances the burr penetration effect. Compared with simple high-speed downward forming, micro-impact can press micro-burrs more thoroughly into the metal substrate, making the flatness of the lower surface edge of the stamped part higher, completely eliminating the problem of burr protrusion, effectively avoiding the wear of rubber parts, wire harnesses and other flexible parts by burrs during subsequent assembly, and improving the assembly safety of the product. Moreover, the combination of low-speed holding pressure in the deceleration zone and subsequent rapid closing effectively suppresses the springback phenomenon of the metal material while forming micro-impact. The metal material completes the initial plastic deformation in the low-speed holding pressure stage, and the rapid closing micro-impact makes the material fully fit with the mold surface. The stability of the lower R-angle dimension after cooling and shaping is greatly improved, and the springback can be controlled within 0.005mm, which is far lower than the springback of traditional processes.

[0042] Although embodiments of the present invention have been disclosed above, they are not limited to the applications listed in the specification and embodiments. They can be applied to various fields suitable for the present invention. For those skilled in the art, other modifications can be easily made. Therefore, without departing from the general concept defined by the claims and their equivalents, the present invention is not limited to the specific details and illustrations shown and described herein.

Claims

1. A controllable double-sided rounded arc forming structure for stamped parts, characterized in that, The system includes an upper die assembly and a lower die assembly. The upper die assembly includes an upper die base and, along the feeding direction, a punching punch, an upper arc forming punch, and a shaping upper die, which are sequentially fixedly installed on the lower surface of the upper die base. The lower die assembly includes a lower die base and, along the feeding direction, a punching die, a shaping lower die, and a lower arc forming punch, which are sequentially fixedly installed on the upper surface of the lower die base. The punching punch and punching die form a first station for punching or trimming parts. The upper arc forming punch and shaping lower die form a second station for rounding the upper surface edge of the part. The shaping upper die and lower arc forming punch form a third station for rounding the lower surface edge of the part. The three stations are fixed in a horizontal position, and the part is driven by an external feeder, progressing sequentially through the first, second, and third stations along the feeding direction.

2. The controllable double-sided rounded arc forming structure for the edge of a stamped part according to claim 1, characterized in that, It also includes a pressure plate, which is located below the upper die base and arranged around the punching punch, the upper arc forming punch and the shaping upper die, and is used to press the part during the stamping process.

3. The controllable double-sided rounded arc forming structure for the edge of a stamped part according to claim 1, characterized in that, The pressure plate is provided with a positioning pin, which is adapted to the pre-punched hole on the part for precise positioning.

4. The controllable double-sided rounded arc forming structure for the edge of a stamped part according to claim 1, characterized in that, It also includes a lifting plate, which is located above the lower mold base and connected to the lower mold base through a lower mold pressure source; in the mold open state, the lifting plate lifts the part upward, so that it is separated from the working surface of the lower mold, so that the feeder can push the part forward by one step.

5. The controllable double-sided rounded arc forming structure for the edge of a stamped part according to claim 1, characterized in that, The lower end face of the upper arc forming punch is a convex curved surface, and the upper end face of the lower forming die is a matching concave arc surface; the lower end face of the upper forming die is a plane or a slightly concave surface, and the upper end face of the lower arc forming punch is a convex curved surface, which are used to cooperate with the upper forming die to complete the rounding and shaping of the lower edge.

6. The controllable double-sided rounded arc forming structure for the edge of a stamped part according to claim 1, characterized in that, The sum of the vertical gap between the upper arc forming punch and the lower forming die and the vertical gap between the upper forming die and the lower arc forming punch is equal to the material thickness of the part.

7. A method for controllable double-sided rounded arc forming of the edge of a stamped part, characterized in that, The method employing the controllable double-sided rounded arc forming structure for the stamped part as described in any one of claims 1-6 includes the following steps: S1. The stamping part to be processed is fed into the forming structure along the feeding direction by an external feeder; at the first station, the stamping part is punched or trimmed by a punching punch and a punching die, and pre-punched holes are formed for subsequent positioning. S2. After completing S1, raise the pressure plate to release the stamping part, and move it forward one step to the second station under the drive of the feeder; then, the pressure plate lowers to press the stamping part. In this state, the upper arc forming punch and the lower forming die cooperate to perform single-sided rounded corner plastic forming on the upper surface edge of the stamping part to form the upper R-corner. S3. After completing S2, the pressure plate is raised again to release the constraint on the stamping part, so that it moves forward one step to the third station under the drive of the feeder; then, the pressure plate is lowered to press the stamping part; in this state, the upper forming die and the lower arc forming punch cooperate to apply reverse pressure to the lower surface edge of the stamping part, to perform lower rounded corner plastic forming and simultaneously flatten the burrs to form the lower R-corner.

8. The method for controllable double-sided rounded arc forming of stamped parts according to claim 7, characterized in that, In step S2, when the upper surface edge of the stamped part is plastically formed by rounding the corners on one side at the second station, the upper arc forming punch is controlled to move at a first downward speed. The first downward speed refers to the speed used by the punch from the first contact with the upper surface edge of the stamped part to the closing position with the lower forming die to complete the forming process, and the process takes no less than 0.3 seconds. In step S3, when the lower surface edge of the stamped part is rounded at the third station, the upper forming die is controlled to move at a second downward speed. The second downward speed refers to the speed used by the upper die from the first contact with the lower surface edge of the stamped part to the complete closure with the lower arc forming punch during the downward process, and the process takes no more than 0.15 seconds. The second downward speed is significantly higher than the first downward speed, and the forming end face of the upper arc forming punch is provided with a micro-ridge extending along the feeding direction, the height of which is 0.02 to 0.08 mm.

9. The method for controllable double-sided rounded arc forming of stamped parts according to claim 8, characterized in that, In step S3, the upper forming die is controlled to descend at a high speed at the second downward speed. Within a range of 1.0 mm to 0.5 mm from the top of the arc forming punch at its end face, the downward speed is reduced to 30% to 50% of the second downward speed and held for 0.02 to 0.05 seconds before being quickly closed to generate controllable micro-impact, enhance burr penetration and suppress springback.

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