活塞销冷镦挤成形微折叠缺陷分析及改进措施  

Micro-folding defect analysis and improvement of cold upsetting-extruding process for piston-pin

作　　者：梁强 LIANG Qiang(Chongqing Key Laboratory of Manufacturing Equipment Mechanism Design and Control,Chongqing Technology and Business University,Chongqing 400067,China;School of Mechanical Engineering,Chongqing Technology and Business University, Chongqing 400067,China)

机构地区：[1]重庆工商大学制造装备机构设计与控制重庆市重点实验室 [2]重庆工商大学机械工程学院

出　　处：《塑性工程学报》2018年第6期99-104,共6页Journal of Plasticity Engineering

基　　金：重庆市基础科学与前沿技术研究专项基金资助项目(cstc2017jcyjAX0175);重庆工商大学高层次人才启动项目(1856002);重庆工商大学校内科研项目(1752009)

摘　　要：针对活塞销采用原冷镦挤工艺方案成形后转角处出现的微折叠缺陷,通过微观组织观察和数值模拟确定微折叠产生于第2次反挤压,产生原因为:反挤压成形过程中,连皮厚度降低至一定值后,金属在转角处径向流动,导致一少部分连皮处金属在杯底转角处出现异常褶皱流动,形成微折叠缺陷。为提高活塞销成形质量和避免成形缺陷,提出采用“反挤压预成形+复合挤压终成形”的改进工艺方案取代两步反挤压成形的原工艺方案。数值模拟结果显示,采用改进工艺方案成形的活塞销锻造流线连续,未出现折叠缺陷。生产实践表明,改进方案可避免活塞销转角处微折叠缺陷的产生,能够满足实际生产要求。When the piston-pin was formed by the original cold upsetting-extruding process,the folding defect was found at the corner.Through microstructure observation and numerical simulation,it was determined that the folding defect occurred during the second backward extrusion. The reason showed in the process of backward extrusion,when the web thickness was reduced to a certain value,the metal flowed in the corner in radial direction,which leaded to abnormal fold flow of a small part of metal at the corner of the bottom of the cup,and formed micro-folding defect. In order to improve the forming quality of piston-pin and avoid forming defects,an improved process scheme of ‘backward extrusion preforming + compound extrusion final forming’was proposed to replace the original process scheme of two-step backward extrusion forming. The numerical simulation results show that the piston-pin forging line formed by the improved process scheme is continuous,and without any folding defect. The production practice shows that the improved scheme can avoid the micro-folding defects at the corner of piston-pin and meet the actual production requirements.

关 键 词：活塞销 冷镦挤 微折叠 数值模拟 

分 类 号：TG316[金属学及工艺—金属压力加工]