Research On The Calculation Method Of The Structure Strength For The Drawing Die Of Automobile Coverings And Its Application

The structure strength of die plays significantly important role in ensuring the quality of stamping. With the extensive use of high strength steel plate, alloy plate and tailor welded plate, the problem of die structure strength has been becoming increasingly prominent. As the finite element analysis for sheet forming gets more and more matured, the calculation of the structural strength of die through the finite element analysis has been the mainstream research. Based on the traditional drawing simulation, a new calculation method of structure strength for the drawing die was constructed in this paper.In this paper, the main works are as follows:(1) Taking the front inner panel as the research subject, the sheet forming process was analyzed by the finite element analysis, also the application of finite element method in calculating the sheet forming force was introduced. The finite element analysis method can conduct the mechanical calculation for the overall deformation of the sheet, the forming results which can meet the engineering application standard and the accurate sheet forming force were obtained by adjusting the stamping parameters. In addition, the forming force was measured, and the accuracy of the finite element calculation method was verified by contrast of the forming forces of experiment and the counterpart of simulation.(2) Taking the drawing die of the front inner panel as the research subjects, a new calculation method of its structure strength was constructed. This method was based on the drawing simulation of traditional sheet forming, the calculation of the structure strength of the die was realized by using the solid element of the die to replace the shell element. The detailed method was as follows: the precise forming force of the sheet and corresponding process parameters of stamping was obtained through finite element analysis of sheet forming, then the finite element analysis was carried out again with the same stamping process parameters. When the stamping stroke proceeded at the last 1 to 2 millimeter, the fluid element of the die was imported into the simulation file to replace the corresponding shell element, then it was defined as elastic and plastic body(sheet).When the rest strokes were completed, the distribution of die structure strength was obtained. The method is simple and convenient, so it is universal to the calculation of structural strength of the die.(3) Aiming at the deformation problem of the drawing die at work, a measurement method of die deformation was presented, and the corresponding device measuring was designed. The method has no impact on the die structure and the drawing process. Therefore, the experimental results were more accurate. The accuracy of the calculation method for the structure strength of the die was analyzed and verified through the measurement for the real deformation of the drawing die of the inner door panel.