Method for acquiring die surface deformation compensation value of stamping die

Abstract

The invention relates to the technical field of die design, in particular to a method for acquiring a die surface deformation compensation value of a stamping die. The method comprises the specific steps that S1, a press table top deformation measuring system is adopted, and the deformation amount of a press under a certain load is collected; s2, establishing a simulation model of a measurement system by adopting Hypermesh software, and obtaining a simplified substitution model of a press table board and a sliding block by combining the collected experimental data through size optimization; s3, cleaning and grid division are conducted on the geometric structure of the mold, and accessory structures which do not affect the strength are removed; s4, combining the simplified model with the die grid model, adding load and constraint of a press machine, and performing stamping simulation; and S5, generating a die surface deformation contour map according to a simulation result, and obtaining a die surface deformation compensation value. Compared with the prior art, by combining a high-precision measurement technology and numerical simulation analysis, technical support can be provided for design and manufacturing of the stamping die, and progress and development of the die industry are promoted.

Description

Technical Field

[0001] The present invention relates to the technical field of die design, and more particularly to a method for obtaining the deformation compensation value of the die surface of a stamping die. Background Art

[0002] With the rapid development of other automotive manufacturing industries, the shapes of stamping parts are becoming increasingly complex, and the requirements for die accuracy are also increasing. Especially in the field of stamping die design and manufacturing, the accuracy and efficiency of the die are directly related to production costs and product quality.

[0003] First of all, the workbench of most current presses is not a solid structure, but a hollow structure composed of multiple reinforcing ribs. The purpose of this design is to improve the load-bearing capacity of the workbench, but it also results in inconsistent stiffness in various parts of the workbench. When the press operates, the uneven stiffness of the structure causes different degrees of elastic deformation of the workbench under the action of the load, which in turn leads to the deformation of the die due to ineffective support. Therefore, the clearance between the upper and lower dies may deviate during the stamping process, affecting the forming quality of the stamping parts. Secondly, the shapes of stamping parts produced in the automotive industry are becoming increasingly complex, and the required forming force is constantly increasing. The huge forming force acting on the workbench and the die will damage the normal mating clearance of the die, affecting the closing accuracy of the die and reducing the lapping rate of the die.

[0004] Currently, in die production practice, the means of die surface deformation compensation are mostly based on the compensation experience of similar parts in the past or only corrected according to a certain proportion based on the size of the die, lacking a scientific basis, which may cause repeated and ineffective trial and error, ultimately leading to an increase in die development costs and an extension of the R & D cycle.

[0005] At the same time, with the development of computer technology, the application of numerical simulation technology in die R & D has become increasingly popular. However, most current stamping simulations calculate using a rigid die surface, ignoring the influence of die and press workbench surface deformation, which results in differences and inconsistencies between the simulation results and the actual effects. In addition, even if an overall model including the press table is established, there are often problems such as long calculation time and difficulty in making the boundary conditions consistent with the actual stamping production line, thus restricting its widespread application.

[0006] In summary, the influence of press deformation on the die is a complex and important issue. Currently, there is a lack of reliable compensation methods in the industry, which leads to a large amount of uncertainty in the die production debugging process. Therefore, there is an urgent need for a scientific, reasonable and effective method to accurately obtain the die surface compensation value by measuring the stiffness characteristics of the press table and combining simulation. Summary of the Invention

[0007] To overcome the deficiencies of the prior art, the present invention provides a method for obtaining the deformation compensation value of the die surface of a stamping die, aiming to overcome the problem that the die closing accuracy does not meet the standard due to the deformation of the press in the prior art.

[0008] To achieve the above object, a method for obtaining the deformation compensation value of the die surface of a stamping die is designed, including a press table deformation measurement system and Hypermesh software. The characteristics are that the specific steps of the obtaining method are as follows: S1, using the press table deformation measurement system, collect the deformation amount of the press under a certain load;

[0009] S2, use Hypermesh software to establish a simulation model of the measurement system, and combine the collected experimental data to obtain a simplified replacement model of the press table and slider through size optimization;

[0010] S3, clean and mesh the die geometric structure, and remove the accessory structures that do not affect the strength;

[0011] S4, combine the simplified model with the die mesh model, add the load and constraint of the press, and perform stamping simulation; S5, generate a die surface deformation contour map according to the simulation result, and obtain the die surface deformation compensation value.

[0012] In the step S1, the press table deformation measurement system uses high-precision displacement sensors to measure the deformation of the table and the slider, and strain gauges to measure the applied load.

[0013] In the step S2, during the establishment of the simplified replacement model, a size optimization algorithm is used to maximize the retention of the stiffness characteristics of the press table and slider.

[0014] The objective function of the size optimization algorithm is where x i is the simulation value of the i-th measurement point in the simulation model, and t i is the deformation value measured experimentally at the corresponding i-th measurement point.

[0015] The specific steps of the step S2 are as follows:

[0016] S21, establish a simplified finite element model of the press table deformation measurement system in Hypermesh software, mesh the simplified finite element model, define the material properties, boundary conditions, and load magnitude. The overall working condition should be consistent with the measurement steps of the press table deformation measurement system in step S1, including the placement position of the support columns, the stamping speed, and the load magnitude;

[0017] S22. Establish thickness design variables: Define the shell element thickness of the tabletop and the slider as design variables. The thickness variation range of the lower tabletop is 150 - 250 mm; define the thickness variation range of the slider as 40 - 200 mm.

[0018] S23: Establish responses: Use n sensors to measure deformations, that is, n measurement points, and establish displacement responses at the finite element nodes corresponding to the n measurement points in the simulation model.

[0019] S24: Define the objective function: where x i is the simulation value corresponding to the i-th measurement point in the simulation model, and t i is the deformation value of the i-th measurement point.

[0020] S25: Set the optimization goal: The optimization goal is to minimize the absolute value of the deformation difference between the corresponding points in the simulation and the experiment, that is, to minimize the optimization function defined in step S24.

[0021] In the said step S3, the cleaning of the die geometric structure includes removing the attached structures of small round corners and small holes.

[0022] In the said step S4, the load and constraint conditions of the press are consistent with the actual production conditions in the simulation to ensure the effectiveness and reliability of the simulation results.

[0023] In the said step S5, the contour map of die surface deformation is generated by post-processing the deformation data in the simulation results.

[0024] Compared with the prior art, the present invention can provide technical support for the design and manufacture of stamping dies and promote the progress and development of the die industry by combining high-precision measurement technology with numerical simulation analysis.

[0025] By the method of combining experiments and simulations, accurately measure the deformation of the press under a certain load, obtain the die surface deformation through simulation, and generate a compensation contour map to improve the closing accuracy and production efficiency of the die. Description of the Drawings

[0026] Figure 1 This is the loading test result of the upper slider of 500T of a certain press in the specific implementation of the present invention.

[0027] Figure 2 This is the simulation model diagram of the measurement system of the present invention.

[0028] Figure 3 This is the thickness distribution diagram after the upper slider size is optimized.

[0029] Figure 4 This is the displacement nephogram of the upper slider after optimization and the displacement diagrams of each measurement point.

[0030] Figure 5 It is the thickness distribution diagram after the workbench is optimized.

[0031] Figure 6 It is the displacement nephogram of the workbench after optimization and the displacement diagram of the measuring points.

[0032] Figure 7 It is a schematic diagram of the geometric cleaning effect, where a is the schematic diagram before cleaning and b is the schematic diagram after cleaning.

[0033] Figure 8 It is the stamping finite element model diagram.

[0034] Figure 9 It is the stamping finite element analysis result.

[0035] Figure 10 It is the contour map of deformation compensation. Specific implementation manners

[0036] The following further describes the present invention with reference to the accompanying drawings.

[0037] The specific steps of the acquisition method of the present invention are as follows:

[0038] S1. Use a press table deformation measurement system to collect the deformation amount of the press under a certain load.

[0039] Use a press table deformation measurement system composed of multiple components including high-precision displacement sensors, aluminum alloy test brackets, hydraulic balance systems, support steel columns, data acquisition systems, etc. to measure the deformation of the press table and slider under a certain load, and obtain the stiffness data of the press. As Figure 1 shown.

[0040] S2. Use Hypermesh software to establish a simulation model of the measurement system, as Figure 2 shown, and obtain a simplified alternative model of the press table and slider by size optimization in combination with the collected experimental data.

[0041] The detailed process of step S2 is as follows:

[0042] S21: Establish a simplified finite element model of the measurement system in Hypermesh software, perform mesh division on the model, define material properties, boundary conditions, and load magnitudes, and the overall working conditions should be the same as those in the measurement step of S1, including the placement position of the support columns, stamping speed, and load magnitude, etc.

[0043] S22: Establish thickness design variables: To accurately characterize the stiffness of different parts of the press, the shell element thicknesses of the table and the slider are defined as design variables. The thickness variation range of the lower table is 150 - 250 mm. There are rib structures with relatively small thicknesses on the slider, so the thickness variation range of the slider is defined as 40 - 200 mm. As Figure 3 , Figure 4 shown.

[0044] S23: Establish responses: In this embodiment, 18 sensors are used to measure deformations, that is, 18 measurement points. Displacement responses are established at the finite element nodes corresponding to the 18 measurement points in the simulation model.

[0045] S24: Define the objective function: where x i is the simulation value corresponding to the i-th measurement point in the simulation model, and t i is the deformation value of the i-th measurement point.

[0046] S25: Set the optimization objective: The optimization objective is to minimize the absolute value of the deformation difference between the corresponding points in the simulation and the experiment, that is, to minimize the optimization function defined in S24. The optimization results are as Figures 5 to 8 shown.

[0047] S3. Clean up the die geometry structure and perform mesh division to remove the accessory structures that do not affect the strength.

[0048] First, clean up the die CAD model to remove the small round corners and weight reduction holes that have little influence on the die strength. The purpose of the cleanup is to reduce the computational complexity and improve the mesh quality. After processing the geometry structure, use Hypermesh software for mesh division. When dividing, the mesh of the die surface needs to be refined (3 mm) to ensure sufficient accuracy for the simulation calculation. The meshes of the die base and other accessory structures can be slightly larger to shorten the calculation time. As Figure 7 shown, a is the schematic diagram before cleanup, and b is the schematic diagram after cleanup.

[0049] S4. Combine the simplified model with the die mesh model, add the loads and constraints of the press, and perform stamping simulation.

[0050] First, combine the simplified press model with the meshed die model. After size optimization, the Hypermesh software will write a binary script file named filename.HM.comp.tcl in the calculation folder, where filename is the name of the model. The binary file contains the thickness information of the model. After running in Hypermesh, layers with different thicknesses will be automatically created, and corresponding materials (structural steel) and thicknesses will be defined for the corresponding layers. Then, according to the actual stamping process, set the corresponding loads and boundary conditions in the simulation software. Finally, perform the simulation calculation to obtain the die surface deformation of the die during actual stamping.

[0051] S5. Generate a die surface deformation contour map based on the simulation results to obtain the die surface deformation compensation value.

[0052] View the simulation results. Read the simulation results in the post-processing software Hyperview, as Figure 9 shown.

[0053] Taking the upper die of the present invention as an example, obtain the die surface deformation compensation value. Since the deformation compensation only needs to compensate for the relative deformation value of the die surface, that is, the overall deformation part does not need to be compensated. After subtracting the minimum die surface Z-direction deformation of -0.32, a die surface compensation contour map is obtained, as Figure 10 shown. This compensation value can be used for subsequent die design adjustments, such as adding necessary tapers or modifying the corresponding fit clearances in the design to offset the decrease in die closing accuracy caused by press deformation.

[0054] Through the above detailed implementation methods, the method of the present invention can effectively obtain the compensation value of the die surface deformation of the stamping die, thereby solving the problem of unqualified die closing accuracy caused by press deformation. This method combines systematic measurement and numerical simulation, providing a scientific basis and technical support for die design and manufacturing.

Claims

1. A method for obtaining a deformation compensation value of a stamping die surface, comprising a press table deformation measurement system and Hypermesh software, characterized in that: The specific steps for obtaining the method are as follows: S1, using the press table deformation measurement system to collect the deformation of the press under a certain load; S2, using Hypermesh software to build a simulation model of the measurement system, and combining the collected experimental data with dimensional optimization to obtain a simplified alternative model of the press table and slide; S3, clean up and mesh the mold geometry to remove the auxiliary structures that do not affect the strength; S4, combining the simplified model with the die mesh model, adding the loads and constraints of the press, and performing stamping simulation; S5, generating a die surface deformation contour map according to the simulation results, and obtaining a die surface deformation compensation value.

2. A method for obtaining a deformation compensation value of a stamping die surface according to claim 1, characterized in that: In the step S1, the press table deformation measurement system uses a high-precision displacement sensor to measure the deformation of the table and the slider, and a strain gauge to measure the applied load.

3. The method for obtaining the deformation compensation value of the stamping die surface according to claim 1, characterized in that: In the step S2, the simplified alternative model is established by using a size optimization algorithm to maximize the retention of the stiffness characteristics of the press table and the slide.

4. The method for obtaining the deformation compensation value of the stamping die surface according to claim 3, characterized in that: The objective function of the size optimization algorithm is Among them, x i is the simulation value of the i-th measurement point in the simulation model, t i is the deformation value measured in the experiment at the corresponding i-th measuring point.

5. A method for obtaining a deformation compensation value of a stamping die surface according to claim 1 or 3, characterized in that: The specific steps of step S2 are as follows: S21, establish a simplified finite element model of the press table deformation measurement system in Hypermesh software, mesh the simplified finite element model, define material properties, boundary conditions and load size, and the overall working condition should be consistent with the measurement steps of the press table deformation measurement system in step S1, including the placement of the support column, the stamping speed and the load size; S22, establish thickness design variables: define the shell element thickness of the table and slider as design variables, the thickness range of the lower table is 150-250mm; define the thickness range of the slider is 40-200mm; S23: Establishing response: using n sensors to measure deformation, i.e., n measuring points, and establishing displacement responses on finite element nodes corresponding to the n measuring points in the simulation model; S24: Define the objective function: Among them, x i is the simulation value corresponding to the ith measurement point in the simulation model, t i is the deformation value of the i-th measuring point; S25: Setting optimization goal: The optimization goal is to minimize the absolute value of the deformation difference between the corresponding points in the simulation and the experiment, that is, to minimize the optimization function defined in step S24.

6. The method for obtaining the deformation compensation value of the stamping die surface according to claim 1, characterized in that: In the step S3, the cleaning of the mold geometric structure includes removing small fillets and small holes.

7. The method for obtaining the deformation compensation value of the stamping die surface according to claim 1, characterized in that: In step S4, the load and constraint conditions of the press are consistent with the actual production conditions in the simulation to ensure the validity and reliability of the simulation results.

8. The method for obtaining the deformation compensation value of the stamping die surface according to claim 1, characterized in that: In the step S5, the mold surface deformation contour map is generated by post-processing the deformation data in the simulation results.

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