Research On The Springback Calculation And Compensation For Auto-body Panels

Springback is one of the main defects of the stamping process. And it is also a main factor in preventing accurate dimensions of final products. Recently, with a wide application for new stamping sheet materials like high strength steel and increasingly complicated for stamping shape, springback problem is becoming more and more prominent. The traditional solution is mainly based on the experience which wastes a lot of time and money. With the appearance and development of the numerical simulation technology for sheet metal forming, it is becoming an important research interest to solve the springback problem with the numerical simulation technology. Therefore, this paper studies the springback problem with the numerical simulation technology. The main work of this paper is as follows:1. According to the difference between the tailor welded blanks(TWBs) with different thickness and monolithic, an accurate finite modeling method for TWBs with different thickness is proposed after the influence factors on springback simulation for TWBs with different thickness is analyzed. The method is ac curate setting the positions of neutral layers for sheets with different thickness during the finite modeling process for TWBs with different thickness. Then the tools meshes are set with mesh ladders, and the position of the ladders line is determined by the position of welding line and the drift distance of the welding lin e during the forming process. The finite element models are constructed accurately to simulate the forming process of TWBs with different thickness. The accurate finite modeling method can improve the accuracy of forming and springback prediction. So it can be used in the finite element simulation.2. The iterative springback compensation for automobile panel is studied, and a new construction method for tool mesh is proposed considering the last product compensation results are used to construct the new tool mesh during each springback compensation iteration. This method is based on the forming numerical simulation. Using the correspondence between the blank mesh and tool mesh, the compensation results of blank mesh are given to the tool mesh to achieve the tool mesh compensation. Firstly, the springback results are obtained after springback simulation with numerical simulation software. With displacement adjustment method, the springback is compensated. And the addendum mesh is stitched on the trimmed pa rt mesh and compensated part mesh respectively after the addendum mesh is adjusted. Then the nodes of tool mesh are mapped onto the forming stitched mesh, and the compensated mapping nodes are constructed on the compensated stitched mesh. After mapping the compensated mapping nodes inversely, the compensated nodes of tool mesh are obtained and the compensated tool mesh is obtained. This method is used to construct the tool mesh during the iterative springback compensation, which keeps the accuracy of the tool mesh and improve the construction efficiency for tool mesh.3. The model of a car`s front cross member is taken for an example to get a stamping numerical simulation. The displacement adjustment is used in the iterative springback compensation, and the whole tool mesh reconstruction method is also used to get the tool mesh. The feasibility of this method is analyzed in this part.