为了解决皮卡尾门外板拉延过程中产生的破裂、起皱的问题,采用数值模拟和灰色关联法相结合的方法对拉延工艺参数进行优化。将料厚最大减薄率和最大增厚率作为优化目标,以圆角和直边段的拉延筋阻力系数、压边力、冲压速度、摩擦系数为工艺参数变量进行5因素4水平的正交试验。在Auto Form软件中进行有限元数值模拟。基于灰色关联分析法,计算出各工艺参数对破裂和起皱综合指标的关联度,给出了最优的工艺参数方案:圆角段拉延筋阻力系数为0.15,直边段拉延筋阻力系数为0.45,压边力为800 k N,冲压速度为3.5 m·s-1,摩擦系数为0.13。应用最优工艺参数组合进行模具制造和现场实际生产,得到了质量良好的冲压件,有效控制了破裂和起皱风险。
Aluminum killed low-carbon steel sheets were cold rolled at different reduction ratios and annealed using different temperatures and holding time.The Vickers hardness was examined.The results show that when cold rolling reduction ratios increase from 40% to 81%,recrystallization temperatures decrease from 602℃ to 572℃ during 4hisochronal annealing,as well recrystallization holding time decreases from 117 min to 5min during isothermal annealing at 610℃.All recrystallization temperatures and holding time can be calculated using the annealing experiment results.Microstructure was examined through electron backscattered diffraction（EBSD）.The results show that as rolling direction preferentially grows,equiaxed grains grow into cake-type during recrystallization.Cake-type grains are more beneficial to obtaining ideal〈111〉//ND（normal direcrtion）orientation texture.{111}orientation grains nucleate and grow up preferentially.Deformation grains of{111}〈110〉orientations grow into new recrystallization grains of{111}〈123〉and{111}〈112〉during recrystallization.Texture formation can be explained by directional nucleation.
