Stamping Simulation Study On The Front Upper Supplement Of Automotive Sliding Door Based On AUTOFORM

The quality of automotive covering parts is greatly affected by sheet forming process.AUTOFORM could be used in simulating the forming process to predict defects and optimize technological parameters. The front upper supplement of automotive sliding door provided by a factory is taken as the research object. An optimization procedure is conducted based on the simulation results to provide a reference for producing high quality products efficiently and economically.The main contents and results are as follows :1.The FEM(Finite Element Method) is introduced. The structure characteristics, quality requirements and formation defects are clarified. AUTOFORM and the basic theory of sheet forming simulation are introduced briefly.2.The forming of the part is rather difficult, because of its complex structure, non-uniform drawing depth, steep facade, large drawing depth and unevenness of boss top. The initial simulation is conducted in which DC03 is the material, the pressing direction is that of minimum backdraft, the sheet is the minimum blank extended by 20 mm. The results show that such defects as cracks, excessive thinning, insufficient stretching and thickening in sheet metal thickness show up.3.To improve the defects, the pressing direction is arranged and several factors are studied.As to the front upper supplement of automotive sliding door the results show that :(1) When the angle around Y direction is 10 degree, the maximum thickening and thinning rate are fairly small, and good formation quality is obtained.(2) Although the stress on rectangular blank is larger than that of expanded blank, the deficiencies of insufficient stretching, comprehensive stress and thickening in material are not improved evidently. On the contrary, the crack increases and material utilization ratio is reduced.(3) When the friction coefficient is 0.15, a mild radial tensile stress is obtained and the defects of wrinkling and insufficient stretching are improved, but an excessive friction coefficient is inclined to cause cracks.(4) When the die clearance is 1.1 times the thickness of sheet, a mild radial force is obtained on the sheet, the risk of crack and other forming defects are meliorated but at an excessively large clearance, wrinkling and material stacking occur due to reduction in radial tensile stress.(5) When the die fillet radius is 14 mm, resistance to feedstock is moderate. When the radius increases friction resistance will decrease in response thus insufficient stretching occurs and the radius increases excessively ripple and winkling occur.(6) Less defects occur when the blank holder force is 400 KN. If it is too small, insufficient stretching, wrinkling and rippling occur. Otherwise, the crack occurs.4.An orthogonal test is conducted to analyze the results obtained above: the optimal parameter combination is A2B1C1D3. The combination is open to be further optimized. After optimizing for another three times the qualified workpiece after drawing is obtained.5.The trimming process is carried out. The springback after drawing and trimming are simulated respectively. It suggests that the springback values are all in the range of 0.81 mm to2.40 mm which conforms to quality requirements. The maximum springback values in district A,C and D decrease, while that of district B increases.