铣削加工3维稳定性预测

Three-dimensional Stability Predication for Milling Processes

传统的2维稳定性极限预测图反映不出进给量对切削稳定性的影响,针对这个问题,提出通过建立与进给量相关的切削力系数模型以反映进给量对切削稳定性的影响。该模型表示为以每齿进给量为变量的二次多项式方程。采用二次回归组合设计方法设计一组变进给量的中心复合试验,通过测量铣削力得到在特定切削条件下的切削力系数,根据最小二乘法估计回归系数。模型的可靠性通过其显著性检验证明,模型的预测能力通过预测铣削力和测量铣削力的拟合情况进行验证。基于该切削力系数模型,在稳定性极限预测中引入进给量因子,使2维稳定性图转化为3维稳定性图,表示出转速、进给量与临界稳定的轴向切深之间的非线性关系。

Feed rate＇s effect on the stability of milling was Absent in traditional two-dimensional stability limit prediction diagrams.To address this issue,a new model of cutting force coefficients was proposed.This model was expressed by a quadratic polynomial equation using feed per tooth as its variable.For this purpose,central composite experiment with a set of feed rates generated by quadratic regression was designed and conducted.Milling force coefficients under certain cutting conditions were derived based on the measured milling force.The regression parameters were then estimated using least square method.The model reliability was verified by significance test.The model prediction performance was validated by comparing the prediction force with the measurement.Based on the proposed model of cutting force coefficients,the feed rate factor was introduced into the stability prediction,which converted the two-dimensional stability diagram into a three-dimensional one and revealed the nonlinear relationship among the rotational speed,feed rate and axial cut depth in the critical stability.