变速器冠轮和中间轴齿轮崩裂原因分析

Analysis on the Cause of Spalling of Crown Wheel and Intermediate Shaft Gear of Transmission

某汽车CVT变速器冠轮和中间轴齿轮在台架试验时发生崩裂。对崩裂的冠轮和中间轴齿轮进行了断口的宏观和微观分析,检测了二者的表面和心部硬度、有效硬化层深度、化学成分和显微组织,以揭示其崩裂的原因。结果表明:冠轮和中间轴齿轮的齿条根部有凸起缺陷和较深的机加工刀痕,导致由于应力集中冠轮疲劳断裂和中间轴齿轮偏载性快速崩裂。在采取优化机加工工艺、装配工艺和改进热处理工艺等措施后,冠轮和中间轴齿轮崩裂的问题得到解决。

Crown wheel and intermediate shaft gear of a CVT transmission for automobile spalled during the bench test.The spalled crown wheel and intermediate shaft gear were tested for macroscopic and microscopic fracture,surface and core hardness,effective hardening depth,chemical composition,and microstructure,for the purpose of identifying the reason why they spalled.The results showed that there were protuberances and deeper machining incisions in rack root of both the crown wheel and the intermediate shaft gear,thus resulting in fatigue fracturing of the crown wheel and rapid spalling of the intermediate shaft gear under eccentric load because of stress concentration.After such measures as optimization of the machining and assembling processes and the improvement in the heat treatment processes was adopted,the problem of the crown wheel and intermediate shaft gear spalling has been solved.