18CrNiMo7-6外圆磨削温度对表层残余应力影响的研究

Research on the Influence of 18CrNiMo7-6 Cylindrical Grinding Temperature on Surface Residual Stress

为研究磨削温度对残余应力形成的影响,运用红外热像仪对工件表面的辐射率值进行测定,并对横向磨削过程中工件表面的温度进行检测,分析了工件每转的横向进给量、工件转速对磨削表面温度的影响,进而揭示了磨削温度这一过程量对残余应力形成的影响程度。相比于工件转速,工件每转的横向进给量对磨削温度的影响较大。随着工件每转的横向进给量的增大,工件表面的温升先快后慢。无论磨削温度的高低,在残余应力形成的过程中磨削的热效应始终与机械效应相抵消,并且在各个方向上的效果大致相等。在18CrNiMo7-6外圆磨削过程中存在温度阈值,当工件温度超过该值(约340℃)时,工件表面将会出现拉应力,并且拉应力水平随着磨削温度的升高而增大。此外,干式磨削也可以带来较好的表面质量,适用于小进给精加工。

In order to study the effect of grinding temperature on the formation of residual stress,the infrared thermal imager was used to measure the emissivity of the workpiece surface,and the temperature of the workpiece surface was detected during the cylindrical plunge grinding.The influence of feed rate per revolution and rotation speed of the workpiece on the grinding surface temperature was analyzed,and the influence of grinding temperature on the formation of residual stress was revealed.Compared with the workpiece speed,the feed rate of workpiece per revolution has a greater impact on the grinding temperature.With the increasing of the feed rate per revolution of the workpiece,the temperature rise of the workpiece surface rises rapidly and then slowly.Regardless of the grinding temperature,the thermal effect of grinding is offset by the mechanical effect during the formation of residual stress,and the effect is approximately equal in all directions.There is a temperature threshold in the 18CrNiMo7-6 cylindrical grinding process.When the workpiece temperature exceeds this value(about 340℃),tensile stress will appear on the surface of the workpiece,and the tensile stress level will increase with the increasing of grinding temperature.In addition,dry grinding can also bring better surface quality and it is suitable for small feed finishing.