八角杆螺栓冷镦卷边折叠缺陷研究及工艺优化  

Research on curling and folding defects for octagonal rod bolts in cold heading and process optimization

作　　者：李旋 李蓉[1] 莫杰 刘坚[1] 郑琼娥 Li Xuan;Li Rong;Mo Jie;Liu Jian;Zheng Qiong′e(College of Mechanical and Vehicle Engineering,Hunan University,Changsha 410082,China;Shenzhen Aero-Fasteners Mfg.Co.,Ltd.,Shenzhen 518109,China)

机构地区：[1]湖南大学机械与运载工程学院,湖南长沙410082 [2]深圳航空标准件有限公司,广东深圳518109

出　　处：《锻压技术》2023年第1期14-22,28,共10页Forging & Stamping Technology

基　　金：国家自然科学基金创新研究群体基金资助项目(51621004);国家自然科学基金资助项目(52105096)。

摘　　要：为了解决某车用八角杆螺栓冷镦生产过程中废品率高、模具寿命过短的问题,借助DEFORM对该螺栓冷镦成形过程进行模拟,发现螺栓冷镦成形中形成的卷边折叠为关键要因。以消除卷边折叠、优化工艺方案为目标,选取模具成形角α、缩径比ε、下压速度v、摩擦因数f这4个因素,设计开展了L_(16)(4^(4))正交试验,获得了各因素对金属堆积卷边折叠的影响程度,结合影响趋势图获得了最优工艺参数组合,即成形角为14°、缩径比为1.1、下压速度为10 mm·s^(-1)、摩擦因数为0.08。采用最优工艺参数组合进行仿真,结果表明:卷边折叠问题得以消除,金属流动性得到改善,成形加载力减少了38.6%,模具上端口崩裂区域的等效应力降低了40.3%。实际生产证明,废品率由87.0%降低至0.1%,模具过早损坏现象得到了解决。研究结果为类似折叠缺陷的改善提供了参考。In order to solve the problems of high scrap rate and short die life in the cold heading production process of a vehicle octagonal rod bolt, the cold heading process of the bolt was simulated by software DEFORM, and the curling and folding formed during the cold heading of bolt were the key factors. Then, with the goal of eliminating the curling and folding and optimizing the process scheme, the four factors of die forming angle α, diameter reduction ratio ε, pressing speed v and friction coefficient f were selected, and L_(16)(4^(4)) orthogonal experiment was designed and carried out. Furthermore, the influence degree of each factor on the curling and folding of metal stacking was obtained, and combined with the influence trend diagram, the optimal combination of process parameters was obtained with the die forming angle of 14°, the diameter reduction ratio of 1.1, the pressing speed of 10 mm·s^(-1)and the friction coefficient of 0.08. The simulation results show that under the optimal process parameters combination, the curling and folding problems are eliminated, the metal fluidity is improved, the forming loading force is reduced by 38.6%, and the equivalent stress in the collapse area of upper port for die is reduced by 40.3%. The actual production proves that the scrap rate is reduced from 87.0% to 0.1%, and the premature damage of die is effectively solved. Thus, the research results provide a reference for the improvement of similar folding defects.

关 键 词：八角杆螺栓 冷镦 卷边折叠 模具成形角 缩径比 下压速度 摩擦因数 

分 类 号：TG376.3[金属学及工艺—金属压力加工]