结构化砂轮磨削加工工件表面形貌建模与实验研究

Modeling and Experimental Research of Ground Workpiece Surface Topography after Grinding with Structured Grinding Wheels

通过对砂轮表面进行实际测量,利用粗糙表面建模方法,考虑砂轮结构化特征参数对砂轮表面连续性的影响,建立了直槽结构化砂轮表面形貌模型;在此基础上,根据砂轮-工件运动学关系以及切削刃的轨迹方程,建立了磨削后工件表面微观形貌的预测模型。开展了直槽结构化电镀CBN砂轮和直槽结构化钎焊CBN砂轮磨削实验,结果表明,磨削后工件轮廓高度算术平均值Ra预测结果与实验结果的相对误差均不超过10%,工件最大轮廓高度Rz预测结果与实验结果的相对误差均不超过12%,验证了预测模型的正确性。研究了不同结构化特征参数对工件表面形貌的影响规律,发现当砂轮开槽宽度相同时,砂轮断续比增大会导致工件表面粗糙度增大;而断续比相同时,因槽宽变化而引起的工件表面粗糙度波动较小。此外,砂轮本身的粗糙程度也是决定磨削后工件表面粗糙度的重要因素,涉及的砂轮表面形貌三个表征参数中,砂轮表面高度的偏态对磨削后工件表面粗糙度的影响程度最大。

The rough surface modeling method was employed to establish the surface topography model of a straight groove structured grinding wheel,considering the influences of structural characteristic parameters on the continuity of the grinding wheel surface through actual measurements.Based on the kinematics relationship between the grinding wheel and workpiece,as well as the trajectory equation of cutting edge,a prediction model for workpiece surface topography after grinding was formulated.Grinding experiments were conducted using both electroplating CBN and brazing CBN straight groove structured grinding wheels.The results show that relative errors between predicted Ra values and experimental ones are below 10%,while relative errors between predicted Rz values and experimental ones are below 12%,thereby validating the accuracy of the prediction model.Furthermore,the influences of various structural parameters on the surface topography of the workpiece were investigated.When the groove width of the grinding wheel remaines constant,an increase in the intermittent ratio of the grinding wheel resultes in an elevation of workpiece surface roughness.Conversely,when the intermittent ratio is held constant,variations in groove width have a minimal effect on workpiece surface roughness.Additionally,it is observed that roughness of the grinding wheel itself is a significant factor determining ground workpiece surface roughness.Among the three characteristic parameters of the grinding wheel surface topography investigated herein,it is observed that the skewness of the grinding wheel surface height exerts the most significant influence on the ground workpiece surface roughness.