轴向超声辅助端面磨削金属表面形貌及粗糙度预测

轴向超声辅助端面磨削被广泛应用于难加工材料加工，而磨削后的表面粗糙度对构件摩擦、疲劳等服役性能有重要影响。超声振幅的大小对轴向超声辅助端面磨削金属表面形貌和粗糙度有较大影响，但是现有模型中并未考虑实际加载对振幅的影响，因此提出了一种考虑加载状态下振幅变化的轴向超声辅助端面磨削金属表面形貌及粗糙度预测方法。根据砂轮粒度及尺寸建立了考虑磨粒随机分布的砂轮端面模型，并对轴向超声辅助端面磨削磨粒的三维磨削轨迹进行了数学描述，生成了加工后的表面三维数据矩阵并对表面粗糙数值进行了计算。在此基础上，研究了粗糙度随振幅的变化规律，提出了振幅衰减形貌映射系数这一概念，并给出了其标定方法。通过振幅衰减形貌映射系数近似计算出加载状态下的振幅并代入到所建立的轴向超声辅助端面磨削表面形貌及粗糙度预测模型中，实现了金属表面形貌模拟及粗糙度预测。最后，通过试验对所建模型的正确性进行了验证。

Surface Topography and Roughness Prediction of Axial Ultrasonic Assisted Facing Grinding Metal

Axial ultrasonic assisted face grinding is widely used in difficult-to-machine material machining and the surface topography and roughness, which have significant influence on friction and fatigue properties. Ultrasonic vibration amplitude has a considerable influence on axial ultrasonic assisted facing grinding surface topography and roughness. In present surface topography and roughness prediction models, the influence of load on vibration amplitude has not been considered, so an axial ultrasonic assisted face grinding metal surface topography and roughness prediction model considering the variation of amplitude is proposed. A model of grinding wheel end face is built according to the wheel size and granularity. Three dimensional grinding trajectory is described mathematically. The three dimensional surface topography data and roughness of machined surface are calculated. On this basis, variation of surface roughness with ultrasonic vibration amplitude is investigated. Consequently, a concept of amplitude attenuation topography mapping coefficient is processed, and its calibration method is also given. Further, the amplitude with loaded could be calculated via the amplitude attenuation topography mapping coefficient. With the amplitude with loaded, the surface topography and roughness are gained with the axial ultrasonic assisted face grinding metal surface topography and roughness prediction model. Finally, accuracy of the prediction model is verified via axial ultrasonic assisted face grinding experiments.