CN109992912A - A kind of optimal springback compensation coefficient based on VC Method determines method - Google Patents

Abstract

A method for determining an optimal springback compensation coefficient based on a coefficient of variation method, comprising: selecting machined parts and using software to establish a mathematical model; setting materials to be used, and dividing the model into meshes; and performing stamping springback simulation on the model according to process parameters ; Set the maximum allowable error between the springback profile and the prototype surface and obtain the corresponding springback compensation coefficient a value interval a _min < a < a _max , and uniformly select the compensation coefficients a ₁ , a ₂ ... a _n ; The corresponding springback compensation is performed in the simulation software and the punching springback simulation is carried out to obtain n mesh data after springback compensation; Displacement; use the coefficient of variation method to calculate the n sets of data to obtain the optimal springback compensation coefficient. On the basis of eliminating stamping springback to the greatest extent, this method can use the coefficient of variation method to select a springback profile whose profile after springback compensation is more parallel and smoother than the design profile, which greatly improves the precision and quality of stamping parts.

Description

A Determining Method of Optimal Springback Compensation Coefficient Based on Variation Coefficient Method

technical field

The invention belongs to the technical field of stamping die profile design, in particular to a method for determining an optimal springback compensation coefficient based on a variation coefficient method.

Background technique

In the process of forming parts of stamping die, the main defect of springback directly causes the error of the shape and size of stamping parts, which in turn affects the quality and assembly requirements of the actual workpiece in use.

At present, there are two main methods to determine excellent stamping springback compensation parameters to control springback: one is to increase the resistance in sheet metal forming and increase the material by means of process optimization, such as changing the size of the blank and adjusting the structure of the draw bead. The stretching effect can cause sufficient plastic deformation of the sheet and restrain the amount of springback, so as to obtain the optimal process and determine the effect of springback compensation parameters through process control methods, thereby controlling the springback. The main problem is that springback is mainly affected by process factors such as blank holder force, friction conditions, and drawbead arrangement position, and the effect of each factor is not the same. Therefore, it is difficult to optimize the parameters, and this method can only appropriately reduce the springback but cannot eliminate the springback to a large extent, and it is difficult to obtain excellent springback compensation parameters; the other is to use the mold surface compensation method. Under the process conditions, the amount of springback is predicted by CAE technology, and the method of modifying the surface of the drawing die is calculated based on the displacement of the above-mentioned springback amount applied and the internal force after forming. The springback compensation parameter required by the error. Compared with the former, this technology has great advantages, but it also has certain shortcomings. The determined springback compensation parameters and even a series of springback compensation parameters that meet the error requirements are not the best springback compensation parameters for the workpiece profile.

It can be seen that obtaining the optimal springback compensation coefficient that meets the design requirements is a cumbersome and inefficient process. Due to the limited experimental experience of engineers, it is difficult to find the best springback compensation that meets the design requirements at once. How to quickly and efficiently find the optimal springback compensation coefficient that meets the design requirements is an urgent problem for those skilled in the field to solve.

SUMMARY OF THE INVENTION

The purpose of the present invention is to provide a method for determining the optimal springback compensation coefficient based on the coefficient of variation method, which can quickly and efficiently obtain the optimal springback compensation coefficient that meets the design requirements, and avoids the need for engineers to manually determine the springback compensation coefficient. Repeated adjustments to improve work efficiency.

The present invention is achieved through the following technical solutions:

A method for determining the optimal springback compensation coefficient based on the coefficient of variation method, comprising:

1) Select the parts to be processed, and use simulation software to establish a mathematical model of the parts

2) Set the material used for the part to be processed, and divide the part model into finite element mesh;

3) According to the mathematical model profile of the part and the process parameters of the part, carry out stamping simulation simulation processing on the model, and obtain the mesh data when the model is stamped and the mesh data after the stamping springback;

4) Set the maximum allowable error between the stamping springback geometric profile of the part and the original design profile and determine the value range of the springback compensation coefficient a of the corresponding springback profile a _min <a < a _max , uniform Select a series of compensation coefficients a ₁ , a ₂ ... a _n ;

5) For the n compensation coefficients selected above, use simulation software to perform corresponding springback compensation and carry out punching springback simulation simulation to obtain n grid node data after springback compensation;

6) The displacement of the main nodes of the above-mentioned n compensated springback profile meshes relative to the original nodes of the original design profile is measured by the simulation software;

7) Use the formula of the coefficient of variation method Among them, N represents the number of overall data, and u represents the average value of the overall data. The n groups of distance data obtained above are calculated respectively, and the results of each group of data are obtained;

8) Compare the n groups of results obtained in 7), find the one with the smallest value, and the corresponding a _i is the optimal compensation coefficient.

Further, when uniformly taking a series of coefficient values for the value range of the springback compensation coefficient, n should be as large as possible within a reasonable range, so that the optimal springback compensation coefficient obtained in this way is more accurate.

Further, the main nodes of the springback grid should be uniformly selected on the model profile grid.

Further, when processing the measured node displacement data, the coefficient of variation method is used.

The beneficial effects brought by the present invention are:

Through the method of the present application, it is possible to obtain an optimal springback compensation coefficient that makes the springback compensation more accurate and the workpiece profile the best, avoids the engineer from repeatedly modifying the springback compensation coefficient, and improves the mold development efficiency.

Description of drawings

FIG. 1 is a schematic flowchart of a method for determining an optimal springback compensation coefficient based on the coefficient of variation method of the present invention.

Detailed ways

The technical solutions of the present invention will be described in detail by the following examples. The following examples are only exemplary, and can only be used to explain and illustrate the technical solutions of the present invention, but cannot be construed as limitations on the technical solutions of the present invention.

As shown in Figure 1, the present invention provides a method for determining the optimal springback compensation coefficient based on the coefficient of variation method, comprising the following steps:

Step 1: select the parts to be processed, and use simulation software to establish a mathematical model of the parts; in this embodiment, use molding simulation software to establish a digital model for the above-mentioned parts to be processed to obtain detailed data of the product to be processed;

Step 2: Set the material used for the part to be processed, and perform finite element mesh division on the part model; The software used for meshing is also sheet metal forming simulation software;

Step 3: Select the mathematical profile of the product and the process parameters of the product, where the process parameters of the product refer to the data information of the parts corresponding to the selected profile. After the finite element mathematical model is subjected to stamping simulation processing, the mesh data of the material when the simulated stamping is completed and after the stamping rebound is obtained, and the mesh when the above-mentioned stamping action is completed and the mesh after stamping are used af. format output;

Step 4: Set the maximum allowable error between the geometric profile of the part after punching and springback simulation and the design geometric profile of the part, set the value area of the springback compensation coefficient, and evenly generate springback compensation within the value range Coefficient; specifically: the maximum allowable error between the geometric profile of the part after the set stamping springback simulation and the design geometric profile of the part is determined by the engineer according to the technical accuracy requirements of the part, and the value range of the springback compensation coefficient can be determined by the engineer. The formula C=R+a(SR) is determined, where C represents the geometric profile of the part after springback compensation, R represents the design geometric profile of the part, S represents the geometric profile of the part after punching springback simulation, and a represents the springback compensation coefficient . and uniformly select a series of compensation coefficients a ₁ , a ₂ . . . a _n in the acquisition interval;

Step 5: For the n compensation coefficients selected above, the corresponding springback compensation is performed on the model surface in the sheet metal forming simulation software. After the compensation is completed, the stamping simulation is performed again, and finally the springback after the springback compensation is completed is obtained. Grid data, and output the above punched grid data in af format;

Step 6: Import the mesh data at the completion of the punching action in Step 3 and the mesh data after the springback compensation punching in Step 5 into think Design, calculate the corresponding displacement of the mesh nodes after the springback, and evenly select the main nodes to record their displacement distance data;

Step 7: Use the coefficient of variation method formula: Among them, N represents the total number of data, and u represents the mean of the total data. Calculation and analysis of the data of displacement distance of n groups of main grid nodes in the above-mentioned Buju 6;

Step 8: Compare the n groups of data results obtained in Step 7, find the one with the smallest value, and the corresponding a _i is the optimal compensation coefficient.

Claims (4)

1. a method for determining the optimal springback compensation coefficient based on the coefficient of variation method, is characterized in that, the method comprises the following steps: Step 1: Select the part to be processed, and use the simulation software to establish a mathematical model of the part; Step 2: Set the material used for the part to be processed, and divide the part model into finite element mesh; Step 3: according to the mathematical model profile of the part and the process parameters of the part, perform stamping simulation processing on the model, and obtain the mesh data when the model is stamped and the mesh data after the stamping springback; Step 4: Set the maximum allowable error between the stamping springback geometric profile of the part and the original design profile and determine the value range of the springback compensation coefficient a of the corresponding springback profile a _min <a < a _max , uniformly select a series of compensation coefficients a ₁ , a ₂ . . . a _n ; Step 5: For the n compensation coefficients selected above, use simulation software to perform corresponding springback compensation and carry out punching springback simulation simulation to obtain n grid node data after springback compensation; Step 6: The distance between the main nodes of the above-mentioned n compensated springback profile meshes relative to the original nodes of the original design profile is measured through simulation software processing; Step 7: Apply the coefficient of variation formula Among them, N represents the number of overall data, and u represents the average value of the overall data. The n groups of displacement data obtained above are calculated respectively, and the results of each group of data are obtained; Step 8: Compare the n sets of results obtained in Step 7, find the one with the smallest value, and the corresponding ai is the desired optimal compensation coefficient. 2. The method for determining the optimal springback compensation coefficient based on the coefficient of variation method according to claim 1, characterized in that, when uniformly taking a series of coefficient values for the value interval of the springback compensation coefficient, it should be within a reasonable range. Make n as large as possible, so that the optimal springback compensation coefficient obtained is more accurate. 3 . The method for determining the optimal springback compensation coefficient based on the coefficient of variation method according to claim 1 , wherein the main nodes of the springback grid are uniformly selected on the model profile grid. 4 . 4. The method for determining the optimal springback compensation coefficient based on the coefficient of variation method according to claim 1, wherein, when the measured node displacement data is processed, the coefficient of variation formula is used Among them, N represents the total number of data, and u represents the mean of the total data.