A positioning method for improving the boundary accuracy of stamping parts

Abstract

The present application belongs to the field of stamping technology, and specifically relates to a positioning method for improving the boundary accuracy of stamping parts, comprising: step 1: determining a first initial positioning hole and a second initial positioning hole of two different diameters; step 2: determining a first slot hole on the basis of step 1; step 3: determining a second slot hole on the basis of step 1; step 4: setting a first positioning pin and a second positioning pin matching step 1 on the upper die of the forming die; step 5: fixing the plate in the cavity of the forming die; step 6: stamping and forming; step 7: completing the removal of the formed part; the present application solves the problem of limited selection of the positioning hole position, reduces the deformation caused by the flow of material during the forming process, generates boundary constraints during the material flow process, ensures dimensional accuracy and stability, does not require subsequent fine trimming processes and process waste, solves the problems of high tooling investment and low material utilization, saves processes, shortens production lines, and reduces process waste.

Description

Technical Field

[0001] The present invention belongs to the field of stamping technology, and in particular relates to a positioning method for improving the boundary accuracy of a stamping part. Background Art

[0002] The stamping process of automobile sheet metal parts is mainly divided into drawing and blanking. The dimensional accuracy of stamping parts is an important indicator to check whether the parts meet the use requirements. The drawing process is a rough positioning of the outer boundary. The process requires retaining waste allowance, and the subsequent finishing process is added to achieve the boundary design accuracy requirements. The blanking process mostly uses internal holes of parts for positioning. The process does not retain boundary waste allowance, and the boundary dimensional accuracy is guaranteed by the blanking process. In today's promotion of energy conservation, emission reduction and efficiency improvement, the blanking process with higher material utilization and lower cost is the preferred process for industry synchronous engineers. The existing hole positioning method has the following problems: 1. The position selection is limited. The sheet metal positioning hole can only be designed at a position where the material flow distance during the forming process is ≤2mm. If the material flow distance at the positioning hole position is >2mm, the material around the positioning pin will be forcibly pulled and severely deformed, causing material cracking, positioning pins to be broken under force, frequent mold maintenance and other production problems. 2. If the aforementioned serious hole-pulling problem occurs, the only option on-site is to use rough positioning of the outer edge. However, due to the 1mm gap between the locator and the edge of the sheet metal on one side, the consistent positioning of each sheet metal into the mold cannot be guaranteed. 3. Using the blanking forming process with rough positioning of the outer edge, due to the initial positioning error of the sheet metal and the large offset space of the sheet metal during the forming process, the final stamping part edge dimensional accuracy is ±2.0mm. To achieve the dimensional accuracy requirements, residual edge process waste is required, and a fine trimming process is added later, which extends the production line, increases tooling investment costs, and reduces material utilization.

[0003] Patent CN106734570A discloses "a mold stamping process method for automobile covering parts". Its technical solution is to set a product area and a waste area as well as a primary trimming line and a secondary trimming line on the workpiece plate. The primary trimming line is the dividing line between the product area and the waste area. The middle end of the primary trimming line is a reserved punching area for triangular punching. The reserved punching area has two and is distributed side by side along the primary trimming line. The primary trimming and triangular punching of the workpiece are completed simultaneously in the trimming process. The triangular punching is used as the workpiece positioning hole, and then the workpiece is positioned using a positioning pin. Although this method realizes the positioning hole in the turning process and obtains the positioning accuracy of the workpiece, it requires residual boundary process waste, adds the fine trimming process in the subsequent sequence, extends the production line, has high tooling investment costs, and has low material utilization. In addition, the reserved triangular punching hole is an equilateral triangle with a fixed structure. At the same time, the position is determined at the middle end of the single trimming line. The structure and position of the positioning hole are limited. When the part is manufactured, the material around the positioning pin will be forcibly pulled and severely deformed, causing material cracking, the positioning pin to be broken under force, and frequent mold maintenance, which affects production.

[0004] Patent CN112605249A discloses a "Method for Controlling Springback and Cracking in Cold-Stamped High-Strength Steel Automotive Seat Side Panels." The technical solution involves first positioning the workpiece by setting locating holes, completing the forming process and the first punching process while maintaining the positioning. The workpiece is then formed using a machine tool to prevent part shifting during the forming process. Then, punching is performed to prevent the holes from being offset during punching, thereby achieving the precision guarantee for the two larger deformations of the workpiece. Compared with the previous technology, the method of the present invention completes two larger deformations in one positioning, thereby improving the forming precision of the parts without increasing the efficiency and adding the process. In particular, during the punching process, the positioning hole is located in the second punching area. When the second punching is performed, the positioning hole is separated from the part as the punching process is completed. After ensuring the precision of the forming process and the first punching, nothing is left on the part after the overall part is generated. After forming, trimming is performed directly, and after trimming, a series of processes such as punching, turning, and shaping are performed. Moreover, the punching process is divided into two processes, the first punching and the second punching, according to different needs, thereby further ensuring the precision of the workpiece. Although this technical solution is an integrated molding process that does not require assembly and welding, it requires two punching operations after molding to address the deformation of the workpiece during molding. The first punching is a hole with a larger area and a more complex shape, which is used to trim the deformed or cracked parts during stamping. After punching, reaming, turning, and shaping are required to meet the structural strength of the product. The second punching is a hole with a smaller area and a regular shape, and it covers the positioning hole to address the deformation caused by punching around the positioning hole. The production process is complex and the manufacturing cost is high. Since the punching is performed after molding, the punching and trimming positions are uncertain, and the consistency of each product cannot be guaranteed. For products with a large area caused by the first punching, there is a risk that the punching position will affect the product function, causing the entire product to be scrapped. Summary of the Invention

[0005] In response to the defects of the existing technology, the present invention proposes a new positioning method for improving the boundary accuracy of stamping parts. The lengths of the first slot hole and the second slot hole are designed to be the distance of material flow, and the directions of the first slot hole and the second slot hole are the direction of material flow. This can reduce the deformation of the material at the positioning point caused by extrusion and pulling, solve the problem of limited selection of the positioning hole position, and reduce the deformation caused by material flow during the forming process.

[0006] To achieve the above-mentioned purpose, the technical solution adopted by the present invention provides a positioning method for improving the boundary accuracy of stamping parts, comprising the following steps:

[0007] Step 1: According to the lower mold structure of the forming mold, determine two first and second initial positioning holes of different diameters on the unfolded plate of the product;

[0008] Step 2: Based on step 1, determine the first slotted hole, define the center of the first initial positioning hole in step 1 as the first initial positioning point, and use the first initial positioning point as the starting point to determine the center of the first final positioning hole along the opposite direction of the material flow at the first initial positioning hole and the material flow distance. The diameter of the first final positioning hole is smaller than the diameter of the first initial positioning hole, and draw an external common tangent line between the two sides of the first initial positioning hole and the first final positioning hole to form the first slotted hole;

[0009] Step 3: Based on the step 1, a second slot is determined. The center of the second initial positioning hole in step 1 is defined as a second initial positioning point. Starting from the second initial positioning point, the center of the second final positioning hole is determined along the opposite direction of the material flow at the second initial positioning hole and the material flow distance. The diameter of the second final positioning hole is smaller than the diameter of the second initial positioning hole. An external common tangent is drawn between the two sides of the second initial positioning hole and the second final positioning hole to form a second slot.

[0010] Step 4: Determine the first and second initial positioning holes of the product material according to step 1, and set matching first and second positioning pins on the lower mold of the forming mold;

[0011] Step 5: Place the unfolded sheet material on the lower die of the forming die, match the first locating pin and the second locating pin of the lower die with the first preliminary locating hole and the second preliminary locating hole, and make the first locating pin and the second locating pin pass through the corresponding first preliminary locating hole and the second preliminary locating hole. The upper die of the forming die is lowered to fix the sheet material in the cavity of the forming die.

[0012] Step 6: Based on Step 5, the cavity surfaces of the upper die and the lower die contact the sheet material, and the sheet material is elastically deformed by the pressure of multiple contact points in the stamping direction. During the sheet material forming process, the sheet material flows along the direction of the first slot hole and the second slot hole under the constraint of the locating pins. No material is obstructed and deformed in the flow direction. The arc tangents of the first preliminary positioning hole and the second preliminary positioning hole are constrained by the first locating pin and the second locating pin to generate a process constraint force.

[0013] Step 7: Open the mold and take the formed product out of the mold. The product is stamped and formed.

[0014] Furthermore, in step 1, determining two first initial positioning holes and second initial positioning holes of different diameters on the unfolded plate of the product specifically includes the following steps:

[0015] Step 1.1: First, import the product 3D data into the finite element simulation software, and unfold the product into a plate structure according to the process design parameters;

[0016] Step 1.2: Determine the first and second initial positioning holes on the unfolded plate. The lower mold of the forming mold has multiple planar structures. Project the planar structures of the lower mold vertically upward onto the plate to set the first and second initial positioning holes.

[0017] Furthermore, step 2 simulates the downward movement of the upper mold through finite element simulation software, and analyzes the deformation direction and the elongated distance of the first initial positioning hole and the second initial positioning hole after simulation. The deformation direction of the hole is the material flow direction, and the elongated distance of the hole is the material flow distance during the molding process.

[0018] Furthermore, the distance between the center of the first initial positioning hole and the center of the second initial positioning hole is two-thirds of the corresponding length of the sheet material along the distance length direction.

[0019] Furthermore, the distance from the first initial positioning point to the first final positioning point is the material flow distance during the molding process.

[0020] Furthermore, the extension lines of the external common tangents on both sides of the first initial positioning hole and the first final positioning hole intersect, and the external common tangents on both sides form an angle.

[0021] Furthermore, the diameter of the first final positioning hole is 2 mm smaller than the diameter of the first initial positioning hole.

[0022] Furthermore, the positioning method of the second slot hole in step 3 is the same as the positioning method of the first slot hole in step 2.

[0023] The beneficial effects of the present invention are:

[0024] First, the present invention determines two first initial positioning holes and second initial positioning holes with different diameters on the unfolded plate, simulates the forming process by finite element simulation software, and according to the deformation direction of the first initial positioning hole and the second initial positioning hole and the elongated distance of the hole shown by the simulation results, the deformation direction of the hole is the material flow direction, and the elongated distance of the hole is the material flow distance during the forming process. The first final positioning hole and the second final positioning hole are determined by the opposite direction of the material flow and the material flow distance during the forming process. The first initial positioning hole and the first final positioning hole, the second initial positioning hole and the second final positioning hole constitute the first slot hole and the second slot hole. The length of the first slot hole and the second slot hole is designed to be the material flow distance, and the direction of the first slot hole and the second slot hole is the material flow direction. This can reduce the deformation amount of the material at the positioning position caused by the extrusion and pull flow, and solve the problem of limited selection of the positioning hole position.

[0025] Second, the diameters of the first initial positioning hole and the second initial positioning hole of the present invention are different. The first initial positioning hole and the second initial positioning hole are matched and installed with the respective positioning pins on the upper mold to play an anti-rebound role. The first slot hole and the second slot hole are used simultaneously in the stamping and forming process to ensure the position consistency of the sheet material in the mold cavity during the production process, solve the problem of consistency in the initial positioning of the sheet material in the production process and the problem of material constraint in the forming process, and ensure that the dimensional accuracy is stable and controllable;

[0026] Third, the diameter of the first initial positioning hole of the present invention is 2 mm larger than the diameter of the first final positioning hole, and the diameter of the second initial positioning hole is 2 mm larger than the diameter of the second final positioning hole. The outer common tangent of the positioning holes with unequal diameters at both ends can intersect with the unilateral interference of the positioning pin by 1 mm when the extension line in the opposite direction of material flow intersects, and can fit tightly with the outer edge of the positioning pin, generating a restraining force during molding to prevent the positioning pin from sliding toward the final positioning hole during the molding process. The boundary restraining force is generated during the material flow process, ensuring dimensional accuracy and stability, and eliminating the need for subsequent fine trimming processes and process waste. This solves the problems of high tooling investment and low material utilization, saves processes, shortens production lines, and reduces process waste.

[0027] Fourth, the first slot hole and the second slot hole of the present invention can replace the rough positioning of the boundary and solve the problem of serious deformation of the material at the positioning position, ensure the boundary dimensional accuracy of the stamping part, improve material utilization, reduce mold investment costs, save comprehensive production costs, and are also suitable for the hole positioning requirements of different parts using blanking forming technology, and have wide applicability. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is a flow chart of the positioning method for improving the boundary accuracy of stamping parts of the present invention;

[0029] Figure 2 is a schematic structural diagram of the first slot of the present invention;

[0030] Figure 3 This is a schematic diagram of the precise positioning principle of the first slot of the present invention;

[0031] Figure 4 is a schematic structural diagram of the second slot of the present invention;

[0032] Figure 5 2. It is a schematic diagram of the unfolding of a plate according to an embodiment of the present invention;

[0033] Figure 6 This is a schematic diagram of the assembly relationship between the plate positioning hole and the upper mold positioning pin in an embodiment of the present invention. Figure 1 ;

[0034] Figure 7 This is a schematic diagram of the assembly relationship between the plate positioning hole and the upper mold positioning pin in an embodiment of the present invention. Figure 2 ;

[0035] Figure 8 It is a three-dimensional structural diagram of the plate after stamping of an embodiment of the present invention.

[0036] Among them, 1-first slot hole; 10-first initial positioning hole; 100-first initial positioning point; 11-first final positioning hole; 110-first final positioning point; 2-second slot hole; 20-second initial positioning hole; 200-second initial positioning point; 21-second final positioning hole; 210-second final positioning point. DETAILED DESCRIPTION

[0037] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0038] like Figure 1 As shown, the present invention provides a positioning method for improving the boundary accuracy of stamping parts. The method unfolds the product structure into a plate based on finite element simulation software, and specifically includes the following steps:

[0039] Step 1: According to the lower mold structure of the forming mold, determine two first initial positioning holes and second initial positioning holes of different diameters on the unfolded plate of the product.

[0040] Step 2: Determine the first slot hole based on step 1, define the center of the first initial positioning hole in step 1 as the first initial positioning point, and use the first initial positioning point as the starting point to determine the center of the first final positioning hole along the opposite direction of the material flow and the material flow distance at the first initial positioning hole. The diameter of the first final positioning hole is smaller than the diameter of the first initial positioning hole, and the two sides of the first initial positioning hole and the first final positioning hole are made into an external common tangent to form the first slot hole.

[0041] Step 3: Determine the second slot hole based on step 1, define the center of the second initial positioning hole in step 1 as the second initial positioning point, and use the second initial positioning point as the starting point to determine the center of the second final positioning hole along the opposite direction of the material flow and the material flow distance at the second initial positioning hole. The diameter of the second final positioning hole is smaller than the diameter of the second initial positioning hole. Make an external common tangent on both sides of the second initial positioning hole and the second final positioning hole to form a second slot hole.

[0042] Step 4: Determine the first initial positioning hole and the second initial positioning hole of the product material according to step 1, and set matching first positioning pins and second positioning pins on the lower mold of the forming mold.

[0043] Step 5: Place the unfolded sheet material on the lower mold of the forming mold, match the first positioning pin and the second positioning pin of the lower mold with the first initial positioning hole and the second initial positioning hole, make the first positioning pin and the second positioning pin pass through the corresponding first initial positioning hole and the second initial positioning hole, and move the upper mold of the forming mold downward to fix the sheet material in the cavity of the forming mold.

[0044] Step 6: Based on step 5, the cavity surfaces of the upper mold and the lower mold are in contact with the sheet metal, and the sheet metal is elastically deformed by the pressure of multiple contact points in the stamping direction. During the sheet metal forming process, it flows along the direction of the first slot and the second slot under the constraint of the locating pins. There is no obstruction and deformation of the material in the flow direction, and the arc tangents of the first initial positioning hole and the second initial positioning hole are constrained by the first locating pin and the second locating pin to generate process constraints.

[0045] Step 7: Open the mold and take the formed product out of the mold. The product is stamped and formed.

[0046] Specifically, in step 1, two first initial positioning holes and second initial positioning holes with different diameters are determined on the unfolded plate of the product, which specifically includes the following steps:

[0047] Step 1.1: First, import the product 3D data into the finite element simulation software, and unfold the product into a plate structure according to the process design parameters.

[0048] In this embodiment, the process design parameters include punching direction, tool body setting, material selection, and force setting supplement.

[0049] Step 1.2: Determine the first and second initial positioning holes on the unfolded sheet. The lower die of the forming mold has multiple planar structures. Project these planar structures vertically upward onto the sheet and define the first and second initial positioning holes. The distance from the center of the first initial positioning hole to the center of the second initial positioning hole is two-thirds of the corresponding sheet length along the distance length direction.

[0050] Preferably, the diameter of the first initial positioning hole is larger than the diameter of the second initial positioning hole, which can prevent the plate from being mismatched with the first positioning pin and the second positioning pin of the forming upper mold.

[0051] Specifically, in steps 2 and 3, the downward movement of the upper mold is simulated by finite element simulation software, and the deformation direction and the elongated distance of the first initial positioning hole and the second initial positioning hole after simulation are analyzed. The deformation direction of the hole is the material flow direction, and the elongated distance of the hole is the material flow distance during the molding process.

[0052] like Figure 2As shown, the first slot 1 includes a first initial positioning hole 10 and a first final positioning hole 11. The first initial positioning hole 10 is located outside the edge of the upper mold with a planar structure. The center of the first initial positioning hole 10 is a first initial positioning point 100. Starting from the first initial positioning point 100, the center of the first final positioning hole 11 is determined along the opposite direction of the material flow at the first initial positioning hole 10 and the material flow distance. The center of the first final positioning hole 11 is the first final positioning point 110.

[0053] like Figure 3 As shown, the dotted line represents the state of the first slot hole 1 after the initial molding die simulation analysis, the solid line represents the first slot hole 1 in the final state obtained by correcting the reverse direction of material flow and the material flow distance after multiple simulation molding analyses, the angle θ represents the material flow direction adjustment angle, the distance L from the first initial positioning point 100 to the first final positioning point 110 is the material flow distance during the molding process, the diameter of the first final positioning hole 11 is 2 mm smaller than the diameter of the first initial positioning hole 10; the extension lines of the external common tangents on both sides of the first initial positioning hole 10 and the first final positioning hole 11 tend to intersect, which can constrain the flow direction of the material, and the external common tangents on both sides form an angle, which can fit tightly with the outer edge of the first positioning pin, generating a restraining force during molding, and preventing the first positioning pin from sliding toward the first final positioning hole 11 during the molding process.

[0054] like Figure 4 As shown, the positioning method for the second slot 2 is the same as that for the first slot 1. The second slot 2 includes a second initial positioning hole 20 and a second final positioning hole 21. The second initial positioning hole 20 is located outside the edge of the upper mold with a planar structure. The center of the second initial positioning hole 20 is a second initial positioning point 200. Starting from the second initial positioning point 200, the center of the second final positioning hole 21 is determined along the opposite direction and material flow distance at the second initial positioning hole 20. The center of the second final positioning hole 21 is a second final positioning point 210. After multiple simulations and analysis, the opposite direction and material flow distance are corrected to obtain the final state of the second slot 2.

[0055] Example:

[0056] like Figure 5 、 Figure 6 、 Figure 7 、 Figure 8 As shown, taking the rear end upper plate part of a car coat plate as an example, the positioning method for improving the boundary accuracy of the rear end upper plate part of the car coat plate of the present invention includes the following steps:

[0057] Step 1: First, import the rear end upper plate of the coat board into the finite element simulation software and design the process parameters according to the forming process. After expanding the sheet line, add two initial positioning holes of different diameters.

[0058] Step 2: Determine the first slot hole. After the preliminary calculation of the finite element simulation software is completed, check the deformation direction and elongation distance of the hole at the locating pin. Based on the numerical value of the initial analysis result, return to modify the direction and size of the original locating hole and perform secondary calculation analysis. After repeated correction iterative calculations, the first slot hole is obtained. Confirm that the locating pin does not pull the hole during the forming process, the sheet metal positioning is stable and controllable, and meets the process requirements. Finally, the first slot hole is output as the final process locating slot.

[0059] Step 3: Determine the second slot using the same method as step 2.

[0060] Step 4: Set two circular positioning pins on the upper mold with the same size as the two positioning circular holes of the plate to position the plate during the forming process.

[0061] Step 5: Place the unfolded upper plate of the rear end of the automobile coat plate on the lower mold of the forming mold, and lower the upper mold of the forming mold so that the two positioning pins of the upper mold pass through the initial positioning holes of the first slot and the second slot of the plate, and fix the plate in the cavity of the forming mold.

[0062] Step 6: The upper die descends, and the upper and lower die cavity surfaces contact the sheet metal. Pressure from multiple contact points in the stamping direction causes the sheet metal to elastically deform. Due to the constraints of the guide slots and the locating pins, the sheet metal cannot escape from the locating pins, ensuring effective constraints. From the initial to the final positioning point of the two slots, the sheet metal flows, with only a 1mm bulge along the tangent edge of the arc. No wrinkles or cracks are observed elsewhere. Throughout the forming process, the sheet metal flows within the constraints of the locating pins. Since the deformation of the material around the locating pins is minimal, it does not affect the removal of the part from the mold after forming.

[0063] Step 7: Open the mold and remove the formed upper rear end plate parts of the automobile coat plate from the mold. The upper rear end plate parts of the automobile coat plate are stamped and formed.

[0064] The positioning method for improving the boundary accuracy of stamping parts of the present invention eliminates process trimming waste, directly blanks the parts into place, improves material utilization, reduces trimming process molds, and reduces stamping processes; ultimately, it meets tolerance requirements and maximizes benefits from the stamping process and the number of molds.

[0065] The above is only an embodiment of the present invention, and common sense such as the specific structure and characteristics of the scheme are not described in detail here. For those skilled in the art, it is obvious that the present invention is not limited to the details of the above exemplary embodiments, and the present invention can be implemented in other specific forms without departing from the spirit or basic characteristics of the present invention. Therefore, from any point of view, the embodiments should be regarded as exemplary and non-restrictive. The scope of the present invention is defined by the appended claims rather than the above description, and it is intended that all changes that fall within the meaning and scope of the equivalent elements of the claims are included in the present invention. Any figure mark in the claims should not be regarded as limiting the claim involved.

Claims

1. A positioning method for improving the boundary accuracy of stamping parts, characterized in that: The following steps are involved: Step 1: According to the lower mold structure of the forming mold, determine two first and second initial positioning holes of different diameters on the unfolded plate of the product; Step 2: Based on step 1, determine the first slotted hole, define the center of the first initial positioning hole in step 1 as the first initial positioning point, and use the first initial positioning point as the starting point to determine the center of the first final positioning hole along the opposite direction of the material flow at the first initial positioning hole and the material flow distance. The diameter of the first final positioning hole is smaller than the diameter of the first initial positioning hole, and draw an external common tangent line between the two sides of the first initial positioning hole and the first final positioning hole to form the first slotted hole; Step 3: Based on the step 1, a second slot is determined. The center of the second initial positioning hole in step 1 is defined as a second initial positioning point. Starting from the second initial positioning point, the center of the second final positioning hole is determined along the opposite direction of the material flow at the second initial positioning hole and the material flow distance. The diameter of the second final positioning hole is smaller than the diameter of the second initial positioning hole. An external common tangent is drawn between the two sides of the second initial positioning hole and the second final positioning hole to form a second slot. Step 4: Determine the first and second initial positioning holes of the product material according to step 1, and set matching first and second positioning pins on the lower mold of the forming mold; Step 5: Place the unfolded sheet material on the lower die of the forming die, match the first locating pin and the second locating pin of the lower die with the first preliminary locating hole and the second preliminary locating hole, and make the first locating pin and the second locating pin pass through the corresponding first preliminary locating hole and the second preliminary locating hole. The upper die of the forming die is lowered to fix the sheet material in the cavity of the forming die. Step 6: Based on Step 5, the cavity surfaces of the upper die and the lower die contact the sheet material, and the sheet material is elastically deformed by the pressure of multiple contact points in the stamping direction. During the sheet material forming process, the sheet material flows along the direction of the first slot hole and the second slot hole under the constraint of the locating pins. No material is obstructed and deformed in the flow direction. The arc tangents of the first preliminary positioning hole and the second preliminary positioning hole are constrained by the first locating pin and the second locating pin to generate a process constraint force. Step 7: Open the mold and take the formed product out of the mold. The product is stamped and formed.

2. The positioning method for improving the boundary accuracy of stamping parts according to claim 1 is characterized in that: In step 1, two first and second initial positioning holes with different diameters are determined on the unfolded plate of the product, specifically including the following steps: Step 1.1: First, import the product 3D data into the finite element simulation software, and unfold the product into a plate structure according to the process design parameters; Step 1.2: Determine the first and second initial positioning holes on the unfolded plate. The lower mold of the forming mold has multiple planar structures. Project the planar structures of the lower mold vertically upward onto the plate to set the first and second initial positioning holes.

3. The positioning method for improving the boundary accuracy of stamping parts according to claim 1, characterized in that: The step 2 simulates the downward movement of the upper mold through finite element simulation software, and analyzes the deformation direction and the elongated distance of the first initial positioning hole and the second initial positioning hole after simulation. The deformation direction of the hole is the material flow direction, and the elongated distance of the hole is the material flow distance during the molding process.

4. The positioning method for improving the boundary accuracy of stamping parts according to claim 1, characterized in that: The distance between the center of the first initial positioning hole and the center of the second initial positioning hole is two-thirds of the corresponding length of the sheet material along the distance length direction.

5. The positioning method for improving the boundary accuracy of stamping parts according to claim 1, characterized in that: The distance from the first initial positioning point to the first final positioning point is the material flow distance during the molding process.

6. The positioning method for improving the boundary accuracy of stamping parts according to claim 1, characterized in that: Extension lines of the external common tangents on both sides of the first initial positioning hole and the first final positioning hole intersect, and the external common tangents on both sides form an angle.

7. The positioning method for improving the boundary accuracy of stamping parts according to claim 1, characterized in that: The diameter of the first final positioning hole is 2 mm smaller than the diameter of the first initial positioning hole.

8. The positioning method for improving the boundary accuracy of stamping parts according to claim 1, characterized in that: The positioning method of the second slot hole in step 3 is the same as the positioning method of the first slot hole in step 2.

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