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起皱、局部壁厚过度减薄是封头冷拉深常见的缺陷,严重制约着拉深封头质量、成形极限的提高以及生产过程的正常进行。文章采用ABAQUS软件建立椭球封头拉深成形的三维有限元模型,并验证该模型的可靠性;发现了椭球封头拉深过程中易于出现的悬空区起皱和过度减薄两种缺陷,并分析了其形成机理,同时研究了工艺参数对缺陷产生的影响规律。研究发现,悬空区承受双向压应力区域的范围与周向压应力的大小对起皱影响明显,而切向拉应力对壁厚的减薄影响显著。增大压边力、摩擦系数和减小凹模圆角半径,可减小悬空区承受双向压应力区域的面积和周向压应力值,进而减小起皱的倾向,而过大的压边力、摩擦系数和过小的凹模圆角半径,则导致悬空区切向拉应力过大,可加剧壁厚的减薄。
Wrinkling and over-thinning of the local wall thickness are common defects in the cold drawing of the head, which severely constrain the quality of the drawing head, increase the forming limit, and ensure the normal progress of the production process. In this paper, ABAQUS software was used to establish the three-dimensional finite element model of the ellipsoidal head drawing and to verify the reliability of the model. The defects of wrinkling and over-thinning of the vacant area in the ellipsoidal head drawing process were found. , And analyzed its formation mechanism, at the same time studied the influence of process parameters on defects. It is found that the extent of the area subjected to bidirectional compressive stress in the open area and the magnitude of circumferential compressive stress have a significant effect on the wrinkling, while the tangential tensile stress has a significant effect on the thinning of the wall thickness. Increasing the blank holder force, the friction coefficient and reducing the fillet radius of the die can reduce the area and circumferential compressive stress of the dangling area under the bi-directional compressive stress, thereby reducing the tendency of creasing, while the over-blank holder Force, coefficient of friction and die radius are too small, then lead to dilatation of the tangential tensile stress is too large, can aggravate the thinning of the wall thickness.