Research On The Springback Compensation Method For Automobile Panel Stamping

Springback is an inevitable defect in sheet metal forming process,which has a decisive influence on the size accuracy of the final forming parts.With the wide application of new materials such as high strength steel plates,the problem of springback becomes more and more prominent.The method of controlling springback can be divided into two parts: process control method and springback compensation method.Springback compensation method is becoming the most commonly used method to solve springback because of its simple operation,low cost and complete elimination of springback.In many springback compensation methods,the most successful method is the node displacement reverse compensation method.This method has the advantages of high precision and suitable for complex surface parts.But in the compensation method the compensation surface will appear part feature drift problem,namely feature position error.this error will cause a great impace on the subsequent trimming and assembly,and also makes the final forming accuracy of the part failed to meet the requirements.To solve this problem,a new method of accurate construction of springback compensation surface is proposed based on the node displacement reverse compensation method.This method can get higher feature position accuracy than the node displacement reverse compensation method.The specific research contents of this thesis are as follows:1.On the basis of the deep analysis of the node displacement reverse compensation method,the method of accurate construction of springback compensation surface is put forward.In this thesis,from the angle of the springback path,the error of the node displacement reverse compensation method is pointed out,and the similarity hypothesis of the springback path is put forward.Based on the similarity hypothesis of springback path,the angle between the normal vector of nodes before springback and the normal vector of nodes after springback is used as the angle between the springback path before compensation and the springback path after compensation,and further,a accurate construction method of springback compensation surface along with path compensation is put forward.The model of a car's front cross member is taken for an example to get a springback compensation calculation when the compensation coefficient is 1.The results show that the method of accurate construction of the springback compensation surface can obtain higher feature position accuracy compared with the node displacement reverse compensation method.2.Because the method of accurate construction of the springback compensation surface is based on the similarity hypothesis of the springback path,the springback path is studied in this paper.The model of a car`s front cross member is taken for an example to get a stamping numerical simulation.Comparing the springback path before compensation and the springback path after compensation,it is found that the difference between them is very small.thus the similarity hypothesis of the springback path is verified.3.Based on the similarity hypothesis of springback path,the method of accurate construction of the springback compensation surface is proposed when the springback compensation coefficient is not 1.When the amount of compensation is multiplied by the spingback compensation coefficient,in general,the amount of compensation is extended or shortened in a straight line.But in fact,the node should be changed along with the path.Therefore,the method that the node is changed along with the path is put forward in this paper in order to deal with the springback compensation coefficient.The model of a car's front cross member is taken for an example to get a springback compensation calculation when the compensation coefficient is not 1,and the results show that the method that the node is changed along with the path can obtain higher feature position accuracy compared with the node displacement reverse compensation method which node is changed along a straight line.