A method for reducing the clamping force on a workpiece under inspection fixture conditions

Abstract

This invention relates to a method for reducing the clamping force on a workpiece under fixture conditions, comprising: first, performing full-process CAE simulation of the forming and springback process of the workpiece; second, converting the free springback of the workpiece into clamping springback based on the positional interchange of RPS points; third, performing multi-round iterative compensation using Autoform software; and fourth, exporting the surface from Autoform software and reconstructing surface A. This invention can guarantee the surface quality after springback compensation; minimize the free springback value of the workpiece, improving the dimensional accuracy of individual parts; has strong repeatability and is not limited by workpiece type; reduces stress on the workpiece under fixture clamping conditions, improves dimensional stability, and reduces dimensional correction costs.

Description

Technical Field

[0001] This invention belongs to the field of stamping die manufacturing technology and relates to a method for reducing the clamping force on the workpiece under the condition of the inspection fixture. Background Technology

[0002] With societal development, people's demands for quality are increasing, and this is also true in the automotive industry. During the stamping stage, in addition to strict requirements on the dimensions of the assembly, the dimensional requirements for individual stamped parts are also becoming increasingly stringent. Not only must the parts be qualified under the fixture clamping condition, but there are also certain requirements for the relaxed state of the parts. Existing methods for solving the dimensional problems of stamped parts include optimizing stamping process design or springback compensation based on the fixture clamping condition. However, using stamping process design to optimize dimensional springback involves significant uncertainty. Even experienced experts often need to conduct multiple trials, and for certain special areas, process optimization alone cannot reduce springback. Another method is springback compensation based on the fixture clamping condition. Theoretically, this method can ensure the parts are qualified under the fixture clamping condition, but after removing the clamp, the parts will experience significant springback, making it difficult to meet customer dimensional requirements.

[0003] In the current automotive body-in-white manufacturing industry, the warpage and springback of stamped parts has always been a difficult problem to solve. As the shapes of parts become increasingly customized, the springback caused by their characteristic shapes is becoming increasingly difficult to mitigate or eliminate through process optimization, often requiring springback compensation. Traditional springback compensation methods use the clamping state of the part in the fixture as a benchmark to compensate for the springback area and amount. However, such compensation often fails to eliminate the internal stress under the fixture clamping state, leading to severe springback and warpage when the clamps on the fixture loosen, affecting part acceptance and potentially requiring die downmilling for dimensional adjustments, impacting both die manufacturing cycle and die quality.

[0004] Patent document CN105868428A relates to the field of sheet metal forming technology and discloses a method for springback compensation of stamped parts. The method includes the following steps: classifying stamped parts according to the characteristics of the mold and the stamped parts, and establishing a stamping simulation parameter list for each type of stamped part to form a stamping simulation parameter library; establishing a standard template and an automatic loop calculation script; wherein the standard template contains standard analysis parameters for each type of stamped part; selecting stamping simulation parameters matching the stamped part to be stamped from the stamping simulation parameter library, and performing full-loop simulation springback compensation on the stamped part to be stamped according to the standard template and the automatic loop calculation script. Compared with existing technologies, this method not only avoids excessive reliance on manual experience in springback compensation, making the springback compensation results more objective and improving the accuracy of springback compensation, but also greatly improves the efficiency of springback analysis and compensation. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to overcome the above-mentioned problems existing in the prior art and to provide a method for reducing the clamping force on the workpiece under the condition of the inspection fixture.

[0006] The purpose of this invention is to provide a method for minimizing the warpage and springback of the workpiece and reducing the stress on the workpiece under the clamping condition of the fixture.

[0007] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0008] To solve the above-mentioned technical problems, the present invention is implemented using the following technical solution:

[0009] A method for reducing the clamping force on a workpiece under inspection conditions includes the following steps:

[0010] The first step is to perform a full-process CAE simulation of the forming and springback process of the part;

[0011] The second step is to convert the free springback of the workpiece into clamping springback based on the position swap of RPS points;

[0012] The third step is to use Autoform software to perform multiple rounds of iterative compensation.

[0013] The fourth step is to export the surface from the Autoform software and reconstruct surface A.

[0014] Furthermore, the full-process CAE simulation of the forming and springback process of the part, as described in the first step, specifically includes:

[0015] (1) Import the stamping process content into Autoform: Import the surface content of each process into Autoform software, simulate it according to the process concept, and check the correctness of the simulation of the process content;

[0016] (2) Handling formability issues: Check whether there are any problems with the formability of the simulation results and whether they meet customer requirements. If they do not meet the requirements, the stamping process needs to be optimized again.

[0017] (3) Handling forced convergence issues: Perform a simulation in Autoform software to check if forced convergence occurs, which may cause deviations in the simulation results. If forced convergence occurs, the problem needs to be investigated and corrected.

[0018] (4) Solve the conformity problem in each process: Check whether there is a misfit when placing the part in the next process. If there is a misfit, the conformity of the subsequent process needs to be processed.

[0019] (5) Determine the free springback of the part: After confirming that there are no problems in the above checks, simulate the free springback state of the final part.

[0020] Furthermore, the second step, which transforms the free springback of the workpiece into clamping springback based on the RPS point interchange position, specifically includes:

[0021] (1) Select the position where the free rebound is zero: Open the AF simulation results, select the value in the rebound mode, and select the position where the free rebound is basically zero;

[0022] (2) Set the clamping point at the position where the free springback is zero: Go to the “Constraints” page, click “Fixed Boundary Condation” at the bottom to enter the clamping mode, select the appropriate clamping point at the position where the free springback is zero, and use clamping springback to replace free springback;

[0023] (3) Cancel the gravity simulation of the part: In the “Constraints” interface, select “No Gravity” and click to check the box to cancel the gravity simulation of the part;

[0024] (4) Determine the similarity between free rebound and clamping rebound: compare whether the free rebound and clamping rebound are basically consistent in terms of rebound trend and rebound value. If they are consistent, the conversion is successful. If they are inconsistent, repeat step (2) and reselect an appropriate clamping position.

[0025] Furthermore, the third step involves using Autoform software for multi-round iterative compensation, specifically including:

[0026] (1) Use Autoform software to automatically compensate the surface: Open Autoform software and use the “Clone for SBCompensatin” command to automatically compensate the selected process surface;

[0027] (2) Simulation verification of the compensated surface: After the automatic compensation of the surface of each process is completed, the full process CAE simulation is performed again to confirm the effectiveness of the automatic compensation;

[0028] (3) Determine the automatic compensation result of Autoform software: After obtaining the simulation result, confirm the springback state of the part. If the target requirements are met, proceed to the next step of exporting the target surface. If the requirements are not met, repeat step (1) and perform the next round of iterative compensation.

[0029] (4) After verifying that the springback condition is met, the clamping point at the position of zero free springback is converted back to the RPS point on the actual fixture for final springback simulation verification.

[0030] (5) Export target surface: Use the “Export” command to export the target surface in igs file format.

[0031] Furthermore, the fourth step, which involves exporting the surface from the Autoform software and reconstructing surface A, specifically includes:

[0032] (1) Surface quality inspection: Check whether the surface quality after compensation output meets the design of the part processing data;

[0033] (2) Local processing of abnormal areas: In the iterative compensation of deformed surfaces, there may be places where the surface quality is poor and does not meet the processing data design. Local abnormal area A-surface reconstruction processing is performed.

[0034] (3) Output the final machined surface and transfer the data.

[0035] Furthermore, the reconstruction of surface A in the local anomaly area is carried out by using Icemsurf software to locally optimize and reconnect the uneven connections of the surface patches.

[0036] Furthermore, the final free springback result of the part was simulated using Autoform software.

[0037] Furthermore, the free springback result is transformed into the clamping springback result based on the RPS point where the free springback is zero, ensuring that the clamping springback result and the free springback result remain unchanged in trend and magnitude.

[0038] Furthermore, Autoform R8 software is used to compensate for the clamping springback of the workpiece instead of the free springback, until the tolerance requirements are met.

[0039] Furthermore, the final CAE dimensional simulation analysis results after springback compensation were verified as qualified using the RPS clamping points on the actual fixture.

[0040] Compared with the prior art, the beneficial effects of the present invention are:

[0041] The method of this invention is simple, can be solidified, and is easy to operate.

[0042] This invention can guarantee the surface quality after springback compensation.

[0043] This invention can minimize the free springback value of the workpiece and improve the dimensional accuracy of a single piece.

[0044] This invention is highly repeatable and is not limited by the type of part.

[0045] This invention can reduce stress in the clamping state of the workpiece, improve dimensional stability, and reduce dimensional correction costs. Attached Figure Description

[0046] The invention will now be further described with reference to the accompanying drawings:

[0047] Figure 1a Schematic diagram 1: Importing stamping process design content into Autoform software for full-process CAE simulation.

[0048] Figure 1b Import the stamping process design into Autoform software for full-process CAE simulation. Figure 2 ;

[0049] Figure 2 A schematic diagram of the free springback result of the part;

[0050] Figure 3 A schematic diagram of the clamping springback result of the workpiece;

[0051] Figure 4 Autoform automatic compensation diagram;

[0052] Figure 5 A diagram illustrating whether the automatic compensation results meet the target requirements;

[0053] Figure 6a Schematic diagram 1: Whether the quality of the output surface after compensation meets the design requirements of the processing data;

[0054] Figure 6b Schematic diagram of whether the output surface quality after compensation meets the design requirements of the machining data. Figure 2 . Detailed Implementation

[0055] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of the embodiments of this invention will be described in more detail below with reference to the accompanying drawings. In the drawings, the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The described embodiments are some, but not all, embodiments of this invention. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain this invention, and should not be construed as limiting the invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention. The embodiments of this invention will be described in detail below with reference to the accompanying drawings.

[0056] In the description of this invention, it should be understood that the terms "center", "longitudinal", "lateral", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "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, they should not be construed as limiting the scope of protection of this invention.

[0057] The present invention will now be described in detail with reference to the accompanying drawings:

[0058] The purpose of this invention is to provide a method for minimizing the warpage and springback of the workpiece and reducing the stress under the clamping condition of the workpiece; this invention has high dimensional stability and saves on mold debugging and modification costs.

[0059] The technical solution of the present invention is: a method for reducing the clamping force on a workpiece under inspection conditions, comprising the following steps:

[0060] The first step is to perform a full-process CAE simulation of the forming and springback process of the part.

[0061] (1) Import the stamping process content into Autoform: Import the surface content of each process into Autoform software, simulate it according to the process concept, and check the correctness of the simulation of the process content;

[0062] (2) Handling formability issues: Check whether there are any problems with the formability of the simulation results and whether they meet customer requirements. If they do not meet the requirements, the stamping process needs to be optimized again.

[0063] (3) Handling forced convergence issues: Perform simulations in Autoform software to check for forced convergence phenomena that cause deviations in simulation results. If forced convergence occurs after a certain number of calculations, the problem needs to be investigated and corrected.

[0064] (4) Solve the conformity problem in each process: Check whether there is a misfit when placing the part in the next process. If there is a misfit, the conformity of the subsequent process needs to be processed.

[0065] (5) Determine the free springback of the part: After confirming that there are no problems in the above checks, simulate the free springback state of the final part.

[0066] The second step is to convert the free springback of the workpiece into clamping springback based on the position swapping of RPS points.

[0067] (1) Select the position where the free rebound is zero: Open the AF simulation results, select the value in the rebound mode, and select the position where the free rebound is basically zero;

[0068] (2) Set the clamping point at the position where the free springback is zero: Go to the “Constraints” page, click “Fixed Boundary Condation” at the bottom to enter the clamping mode, select the appropriate clamping point at the position where the free springback is zero, and use clamping springback to replace free springback;

[0069] (3) Cancel the gravity simulation of the part: In the “Constraints” interface, select “No Gravity” and click to check the box to cancel the gravity simulation of the part;

[0070] (4) Determine the similarity between free rebound and clamping rebound: compare whether the free rebound and clamping rebound are basically consistent in terms of rebound trend and rebound value. If they are consistent, the conversion is successful. If they are inconsistent, repeat step (2) and reselect an appropriate clamping position.

[0071] The third step is to use Autoform software for multi-round iterative compensation.

[0072] (1) Use Autoform software to automatically compensate the surface: Open Autoform software and use the “Clone for SBCompensatin” command to automatically compensate the selected process surface;

[0073] (2) Simulation verification of the compensated surface: After the automatic compensation of the surface of each process is completed, the full process CAE simulation is performed again to confirm the effectiveness of the automatic compensation;

[0074] (3) Determine the automatic compensation result of Autoform software: After obtaining the simulation result, confirm the springback state of the part. If the target requirements are met, the next step of exporting the target surface can be carried out. If the requirements are not met, step (1) can be repeated to carry out the next round of iterative compensation.

[0075] (4) After verifying that the springback condition is met, the clamping point at the zero springback position is converted back to the RPS point on the actual fixture for final springback simulation verification.

[0076] (5) Export target surface: Use the “Export” command to export the target surface in igs file format.

[0077] The fourth step is to export the surface from Autoform software and reconstruct surface A.

[0078] (1) Surface quality inspection: Check whether the surface quality after compensation output meets the design of the part processing data;

[0079] (2) Local processing of abnormal areas: In the iterative compensation of deformed surfaces, there may be places where the surface quality is poor and does not meet the processing data design. Local abnormal area A-surface reconstruction processing is performed.

[0080] The reconstruction of surface A in the local anomaly area is achieved by using Icemsurf software to locally optimize and reconnect the uneven connections of the surface patches.

[0081] (3) Output the final machined surface and transfer the data.

[0082] The positive effects of this invention are: the surface data obtained in the above steps are used for the design of processing data for each process of the part. Experimental results show that this method can reduce the stress in the clamping state of the part, improve dimensional stability, and reduce the cost of dimensional rectification.

[0083] See Figure 1a , Figure 1b The stamping process design was imported into Autoform software for full-process CAE simulation.

[0084] See Figure 2 The free springback result of the part is selected by choosing an appropriate position where the free springback value is close to zero.

[0085] See Figure 3 The free springback result of the workpiece is converted into the clamping springback result.

[0086] See Figure 4 The Autoform automatic compensation diagram shows how to select the process surfaces that need automatic compensation and perform automatic compensation in the software.

[0087] See Figure 5Evaluate whether the automatic compensation results meet the target requirements. If they do, the surface can be output; otherwise, the process can continue iterating for the next round of compensation.

[0088] See Figure 6a , Figure 6b Evaluate whether the quality of the output surface after compensation meets the design requirements of the processing data. If not, perform local A-surface reconstruction optimization.

[0089] This invention relates to a method for reducing the clamping force on a workpiece under fixture conditions. The purpose of this invention is to provide a method to minimize the warpage and springback of the workpiece and reduce the stress under fixture conditions. A method for reducing the clamping force on a workpiece under fixture conditions includes the following steps: First, performing a full-process CAE simulation of the forming and springback process of the workpiece; Second, converting the free springback of the workpiece into clamping springback based on the interchange of RPS points; Third, performing multi-round iterative compensation using Autoform software; Fourth, exporting the surface from Autoform software and reconstructing surface A.

[0090] This invention uses Autoform software to simulate the final free springback result of the workpiece.

[0091] This invention transforms the free springback result into a clamping springback result based on the RPS point at the position where the free springback is zero, ensuring that its trend and magnitude remain basically unchanged.

[0092] This invention utilizes Autoform R8 software to compensate for the clamping springback of the workpiece to meet the tolerance requirements.

[0093] The present invention verifies the final compensated result using the RPS clamping points on the actual inspection fixture.

[0094] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any modifications, equivalent substitutions, and improvements made by those skilled in the art within the scope of the technology disclosed in the present invention, and within the spirit and principles of the present invention, should be included within the scope of protection of the present invention. Furthermore, all content not described in detail in this specification is prior art known to those skilled in the art.

Claims

1. A method of reducing the clamping force experienced by a workpiece in a gage condition, comprising: The method comprises the following steps: First, the forming and springback process of the workpiece is simulated by CAE; Second, the free springback of the workpiece is converted into clamping springback based on the position adjustment of RPS points; Third, multiple rounds of iterative compensation are performed by using Autoform software; Fourth, the curved surface is exported from the Autoform software, and the A surface is reconstructed; The simulation of the forming and springback process of the workpiece in the first step specifically comprises: (1) importing the stamping process content into Autoform: importing the curved surface of each process content into the Autoform software, simulating according to the process idea, and checking the simulation correctness of the process content; (2) processing the formability problem: checking whether the formability of the simulation result has a problem and whether it meets the customer's requirements, if not, re-optimizing the stamping process content; (3) processing the forced convergence problem: simulating in the Autoform software to check whether the forced convergence phenomenon occurs, which causes the simulation result to deviate, if forced convergence occurs, the problem needs to be checked and changed; (4) solving the symbol type problem of each process: checking whether the workpiece placed from each process to the next process has a misfit phenomenon, if there is a misfit phenomenon, the symbol type of the subsequent process needs to be processed; (5) determining the free springback of the workpiece: after confirming that the above checks have no problems, the free springback state of the final workpiece is simulated; The conversion of the free springback of the workpiece into clamping springback based on the position adjustment of RPS points in the second step specifically comprises: (1) selecting the position with zero free springback: opening the AF simulation result, selecting the position with zero free springback in the springback mode; (2) setting the clamping point at the position with zero free springback: entering the "Constraints" page, clicking the "FixedBoundary Condation" below to enter the clamping mode, and appropriately selecting the clamping point at the position with zero free springback to replace the free springback with clamping springback; (3) canceling the gravity simulation of the workpiece: selecting "No Gravity" in the "Constraints" interface and clicking the check to cancel the gravity simulation of the workpiece; (4) determining the similarity between the free springback and the clamping springback: comparing whether the free springback and the clamping springback are basically consistent in the springback trend and the springback value, if consistent, the conversion is successful, if not, repeat step (2) to select appropriate clamping positions; The multiple rounds of iterative compensation by using Autoform software in the third step specifically comprises: (1) automatically compensating the curved surface by using Autoform software: opening the Autoform software and using the "Clone for SBCompensatin" command to automatically compensate the selected process curved surface; (2) verifying the compensated curved surface: after automatically compensating the curved surface of each process, re-performing the full-process CAE simulation to confirm the effectiveness of the automatic compensation; (3) Determine the Autoform software automatic compensation results: after obtaining the simulation results, confirm the springback state of the workpiece, and if the target requirements are met, proceed to the next step of exporting the target surface, and if the requirements are not met, repeat step (1) and perform the next round of iterative compensation; (4) After verifying that the springback state meets the requirements, convert the clamping points with zero free springback positions to RPS points on the actual gauge, and perform final springback simulation verification; (5) Export the target surface: use the "Export" command to export the target surface in igs file format; The fourth step of exporting the surface from the Autoform software and reconstructing the A surface includes: (1) Surface quality inspection: check the surface quality after compensation output to see if it meets the workpiece processing data design; (2) Local processing of abnormal areas: the deformed surface after iterative compensation may have poor surface quality in some areas that do not meet the processing data design, so local A surface reconstruction processing is performed on these abnormal areas; (3) Output the final machining surface and data transmission.

2. The method for reducing the clamping force of a workpiece gauge according to claim 1, characterized in that: The local A surface reconstruction processing is performed by using Icemsurf software to locally optimize and reconnect the surface patches that are not smooth.

3. The method for reducing the clamping force of a workpiece gauge according to claim 2, characterized in that: The Autoform software is used to simulate the final free springback results of the workpiece.

4. The method for reducing the clamping force of a workpiece gauge according to claim 3, characterized in that: The free springback results are converted into RPS point clamping springback results based on the zero free springback position, ensuring that the clamping springback results and free springback results have the same trend and value.

5. The method for reducing the clamping force of a workpiece gauge according to claim 4, characterized in that: The Autoform R8 software is used to replace the clamping springback of the workpiece with the free springback compensation to meet the tolerance requirements.

6. The method for reducing the clamping force of a workpiece gauge according to claim 5, characterized in that: The CAE size simulation analysis results after final springback compensation are verified to be qualified using the RPS clamping points on the actual gauge.

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