齿轮轴螺纹断裂分析及改善措施

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Analysis and improvement of gear shaft thread fracture

GAO Yongqiang， SONG Wenjing ZhengzhouHuaweiGearCo.，Ltd.，Zhengzhou ，，

Abstract： During the assemblyof the drive gear shaft for the rear axle spiral bevel gear，thread fracture occurred at the surface near the R area.The fracture surface is flat with metallic luster.The crack initiates from one side of the surface and expands radially. A black area exists on the surface layer at the crack source.The fracture surface clearly shows two stages of expansion.Comprehensive analysis based on fracture morphology，metallgraphy，hardness， and energy spectrum indicates that the thread fracture is mainly caused by unqualified metallographic structure on the threadsurfaceduring heat treatment，which isacicular martensite.Thesurface hardness of the thread is uneven andfails tomeet the technicalrequirements.There are defects of poor surface roughness inthe machining process， which easilyleads tocrack initiationand fractureat the R corner due to excessive and uneven stress.By changing the thread heat treatment process from the original overall carburizing quenching + high-frequency induction annealing to applying anti-carburizing agent first and then performing high-frequency induction annealing on the thread during heat treatment，it ensures thatno stress concentration occursatthe thread after heat treatment，avoiding thread fracture failures.

Keywords：failure analysis; thread fracture; bevel gear shaft;thread;crackle;stress concentration; high frequency annealing

1序言

在汽车传动中，前后桥主减速器总成起着重要的作用，弧齿锥齿轮副是车桥的核心传动部件，主动齿轮轴上的螺纹主要起固定连接传动轴、传递扭矩的作用，其疲劳寿命直接影响整车驱动桥的寿命。（剩余4578字）