直齿轮冷精锻钢坯卸压孔直径对模具弹性变形的影响

Influence of pressure relief hole diameter of cold precision forging steel billet for spur gear on elastic deformation of mold

针对直齿轮冷精锻成形过程中,模具因承受较大的成形载荷产生弹性变形,进而影响成形齿轮的成形精度等问题,基于径向分流法设计了不同卸压孔直径的钢坯,建立了坯料塑性成形与模具应力分析的有限元模型,研究了不同卸压孔直径对模具弹性变形的影响。根据模具型腔的弹性变形量,采用反补偿法修正了齿模齿廓曲线,并比较了修正前后锻件的变形量。结果表明:随着卸压孔直径的增大,模具弹性变形量先增大后减小,在卸压孔直径d_(0)=Φ20 mm时,模具的弹性变形量最小;模具不同高度的齿腔轮廓平面的弹性变形量变化形势一致,但增量幅度不同;上轮廓平面变形量最大且齿根到齿顶波动幅度大,峰值位于齿顶;齿模齿形修正后锻件的弹性变形量减小了28.6%。设计了3组不同d0的坯料进行成形实验,实验结果与仿真结果基本吻合,通过减小模具弹性变形量可以提高锻齿的尺寸精度。

During the cold precision forging process of spur gears,due to a large forming load,the mold produces elastic deformation which affects the forming accuracy of formed gears.Therefore,in order to solve the above problems,the steel billets with different diameters of pressure relief hole were designed based on the radial shunt method.Then,a finite element model for billet plastic forming and mold stress analysis was established,and the influences of different diameters of pressure relief hole on the elastic deformation of mold were studied.Furthermore,according to the elastic deformation amount of mold cavity,the tooth profile curve of mold was modified by the inverse compensation method,and the deformation amounts of forgings before and after modification were compared.The results show that with the increasing of the diameter of pressure relief hole,the elastic deformation amount of mold increases and then decreases,and the elastic deformation amount of mold is the smallest when the diameter of pressure relief hole d_(0)=Φ20 mm.The elastic deformation amounts of tooth cavity profile plane with different heights of mold change in the same situation,but the incremental magnitude is different.The deformation amount of upper profile plane is the largest and the fluctuation from the root to the top of tooth is large,and the peak is located in the top of tooth.The elastic deformation amount of forgings is reduced by 28.6% after the tooth shape modification of mold.Three groups of billets with different d0 were designed for forming experiments,and the experimental results were basically consistent with the simulation results.Thus,the dimensional accuracy of forged teeth is improved by reducing the elastic deformation amount of mold.