Application Of Numerical Simulation In The Drawing Quality Control Of Engine Hood Exterior Panel

Most of automobile covering parts have complex and irregular shapes, which forming processes are often affected by blank shape, stamping direction and speed, binder force, draw-bead structure and layout, friction condition and gap between die and punch, etc. These affections can lead to many product quality problems, such as severe thinning, wrinkle, warping, crack and greater spring back.Depending on the conventional experiences or stamping again and again to seek the best forming parameter and mould structure, on the one hand the product quality can not be ensured, on the other hand the prime cost can not be decreased, which will become the choke point when new car come into the market. By means of the CAE software, not only the forming drawbacks may be discovered in advance which are detected in stamping process or mould debugging formerly, but also the stamping scheme and the mould design scheme may be simplified and optimized, the time of studying and developing die may be shortened, the quality of forming-product and assembling-car may be improved, as well as the production costs may be reduced.Based on the elastic-plasticity theory of sheet forming and Dynaform(?) software, the drawing and spring-back processes of the BoraA5's engine hook exterior panel were studied, and the drawing parameters and mould parameters were designed by use of orthogonal experiment method in this paper. The effects of binder force, stamping speed, draw-bead depth and the gap between punch and die on the localthickness, wrinkle, crack, and spring back which the exterior panel was drawn were sufficiently studied. According to numerical simulation, the reasons for wrinkle, crack and spring back were comprehensively analyzed, and the corresponding solution of drawing quality was given.The numerical simulation shows that in forming the exterior panel the impact of binder force on the least local thickness and the spring back value is greater, of the stamping speed on the least local thickness greater but on the spring back value littler, of the gap between punch and die on the spring back value greater but on the least local thickness littler, of draw-bead depth on the least local thickness and the spring back value littler. That is the greater the binder force, the littler the least local thickness and the spring-back value;the greater the stamping speed, the littler the least local thickness;the littler the gap between punch and die, the littler the spring-back value.Based on above-mentioned research, the best drawing scheme for exterior panel of BoraA5 engine hood is confirmed: binder force 900KN, draw-bead depth 6mm, stamping speed lOOOmm/s (as 10 times as actual stamping speed) , the gap between punch and die 0.8mm.