不等径制动双筒件复合冷挤工艺及晶粒尺寸演化研究  

Research on compound cold extrusion process and grain size evolution of double cylindrical braking part with unequal diameters

作　　者：鲁志兵[1] 王成勇[1] 张鹏[1] 张心怡[1] 张贺宁[1] 

机构地区：[1]合肥工业大学材料科学与工程学院,安徽合肥230009

出　　处：《锻压技术》2014年第8期129-134,共6页Forging & Stamping Technology

基　　金：国家自然科学基金资助项目(51275146);教育部科学研究重大项目(311025);安徽省自然科学基金资助项目(1208085ME71);国家级大学生创新项目(201210359008)

摘　　要：分析不等径制动双筒件的零件特征,设计了单道次复合冷挤压成形工艺代替传统的多道次拉深方法。为了降低单位挤压力以及增强金属塑性流动的导向性,对挤压空心毛坯进行了局部预制处理。对该零件冷成形进行有限元建模,分析了挤压过程中凸模载荷变化、坯料内部的等效应力分布、晶粒细化效果。绘制了4个阶段的凸模-行程曲线;显示出挤压过程中应力主要集中在分流层和圆角处;模拟了正、反挤部分的晶粒经历拉长破碎聚集拉长的局部细化过程,与金相实验结果吻合。最后利用研究获得的工艺参数试制出合格的产品。The features of double cylindrical braking part with unequal diameters were analyzed. The process of the single step of compound cold extrusion was designed to replace the traditional process of multi-step drawing. In order to reduce extrusion force and to guide the plastic metal flow, some local parts of the hollow blank for extrusion were shaped in advance. The FEM model was built. The changes of punch load, the equivalent stress distribution within the billet and the grain refinement effectiveness were analyzed. The punch-stroke curve shows four stages of the process. Stress concentrates in shunt layer and fillets. Grains in forward extrusion and backward extrusion have the performance of being elongated, being cracked, being gathered and being elongated again by FEA simulation. The process of lo- cal grains refinement is similar with the metallographic experiment results. The qualified forming part is obtained from actual extrusion with the research parameters.

关 键 词：双筒件 复合冷挤压 晶粒度 元胞自动机 

分 类 号：TG376.5[金属学及工艺—金属压力加工]