Research And Application Of Calculating Trimming Contour Methods For Cover Panel

It is very common for sheet metal forming to flange and trim. The shape and dimension after trimming is the most important factor which affects the forming precision. So how to determine the trimming shape and dimension for exact flanging is very important for reducing the period of producing trimming mould and saving the cost. Simultaneously it is a difficult problem in whole mould manufacture.Several common methods of calculating the cutting contour were discussed in this thesis. Geometric development of flanges can receive the initial contour quickly. But it didn't consider the deformation along thick direction. Although establishing the mathematic model of flanges development to indicate trimming line considered the thick variety, it can't represent the true flow of the material in the deformation because the flanging is a complex process. The try-error method can obtain ideal trimming lines through adjusting by hand. But this method is very miscellaneous and will bring much waste.In this thesis it was proposed to simulate the drawing, trimming, flanging by using Error-Adjustment method. The initial trimming lines would be adjusted and optimized in the computer by Adjusting Error. If the shape error between the flanging boundary line and the target is larger than prescribed, the redundant area is subtracted from the initial blank by some amount of volume along the deformation path, and the insufficient volumes are added to the initial blank by the same amount. The optimizing calculation is based on the reality deformation path and the calculation precise is control by the limit error. At the same time computation time was controlled by the maximum iteration. The ideal cutting contour would be obtained.The cutting contours of three typical cover panels were calculated by using the Error-Adjustment method. Firstly using the calculated cutting contour to cut the drawing part, then flange on the flanging mould, and then check the error for flanging part. Try-out the part until it is correct. It is shown that the error of calculated cutting contour is in the range of±1mm through compared it with the correct contour. So using the Error-Adjustment method to calculate cutting contour can reduce the try-out times and period of trimming and flanging effectively.