切向超声振动辅助成形磨削齿轮的切削系数建模与试验研究

Analytical Modeling and Experimental Investigation on Cutting Coefficient during Tangential Ultrasonic Vibration-assisted Forming Grinding Gear

通过对磨粒-工件的运动特性分析,研究了切向齿轮超声成形磨削过程中分离加工机理,建立了超声振动作用下磨粒-工件的切削系数模型,得到了加工参数(砂轮速度、进给速度、超声频率和超声振幅)对切削系数的影响规律。针对切向齿轮超声成形磨削分离加工的特点,进行了齿轮超声成形磨削和普通磨削加工试验,获得不同加工参数对磨削力、磨削温度、残余应力和表面粗糙度的影响规律,并对磨削后表面的微观组织进行分析。试验结果表明:与普通磨削相比,在超声磨削过程中,磨削力、磨削温度和表面粗糙度在一定程度上得到有效的降低。三者的降低幅度随着砂轮转速、进给速度的增加而减小,磨削力、磨削温度的降低幅度随着超声振幅的增加而增大,而表面粗糙度的降低幅度随着超声振幅的增加呈先增加后减小的趋势;同时,齿面的残余压应力得到提高,其增加幅度随着砂轮转速、进给速度的增加而降低,随着超声振幅的增加而增大。此外,超声磨削可以显著改善齿面的纹理状态和表层的显微组织,并实现晶粒的细化。

The separated machining mechanism in tangential ultrasonic vibration-assisted forming grinding gear(TUVAFGG) is investigated and the cutting coefficient model of grain-workpiece is erected on the basis of the kinematic analysis of the grain and the workpiece. And the relationship between the processing parameters(grinding wheel speed, feed rate, ultrasonic frequency and ultrasonic amplitude) and cutting coefficient is acquired. The TUVAFGG and conventional forming grinding gear(CFGG)experiment is performed to explore the characteristics of separated machining. A detailed comparative study of grinding force,grinding temperature, residual stress and surface roughness during the both machining methods is conducted to obtain the effect of various parameters on them, and analyze the microstructure of the gear surface. The experimental results presents that compared with CFGG, the grinding force, grinding temperature and surface roughness are effectively reduced to a certain extent with the increase of grinding wheel speed, feed rate and ultrasonic amplitude during TUVAFGG. The reduction ratio of the three decreases with an increase of grinding wheel speed and feed rate. The grinding force and grinding temperature reduction ratio increased with an increase of ultrasonic amplitude, however, the surface roughness reduction ratio first increases and then decreases. Simultaneously, the residual compressive stress of the tooth surface is improved, and the increase ratio decreases with the increase of grinding wheel speed and feed rate, while enhance with the increase of ultrasonic amplitude. In addition, under the action of ultrasonic vibration, the surface texture state and microstructure of the surface layer can be significantly improved, and the grain can be refined compared with CFGG.