汽车变速箱结合齿坯精锻成形组合凹模设计

Combined die design on precision forging of combined gear blank for automobile gearbox

倒挡结合齿是汽车变速箱中重要的零件,针对某款结合齿坯精锻成形过程中发生的整体模具低周疲劳开裂问题,提出一种适用于热精锻的组合凹模结构。运用有限元分析软件对组合凹模进行模具应力分析,模拟结果表明：采用组合凹模结构可以降低危险区域的拉应力值50%以上,避免了低周疲劳开裂缺陷;增大组合凹模外圈直径可以改善模具受力状况并降低在结合处钻料的风险;适当减小组合凹模过盈量可以避免外圈在工作状态下的塑性变形。

The combined reverse gear is an important part of automobile gearbox. For the low-cycle fatigue cracking of integer die in precision forging of combined gear blank,a combined die structure for hot precision forging was proposed,and the stress analysis of the combined die was conducted by finite element software. The simulation results show that the combined die can reduce the tension stress at the dangerous area by more than 50% and avoid the low-cycle fatigue cracking. Furthermore,the stress state of die is improved and the risk of drilling at the joint is reduced by increasing the diameter of outer ring for the combined die,and the plastic deformation of outer ring in working condition is avoided by reducing the interference of combined die.