五轴侧铣加工瞬时未变形切屑厚度计算模型

Calculation Model of Instantaneous Undeformed Chip Thickness in 5-axis Flank Milling Process

在五轴侧铣加工铣削力建模中,瞬时未变形切屑厚度的计算是铣削力预测的关键环节,直接影响着铣削力预测的精度与效率。为了提高铣削力的预测精度与效率,基于五轴机床空间运动分析,并考虑刀具径向跳动因素,提出了一种五轴侧铣加工瞬时未变形切屑厚度模型。首先,分析了五轴侧铣加工中铣削刃随刀具旋转、摆动与平移的复合运动规律,得到在不同刀位点处各切削刃的坐标位置;其次,考虑刀具径向跳动因素,提出了一种瞬时未变形切屑厚度的快速计算方法;最后,结合参数化厚度补偿的思想,对求解出的瞬时未变形切屑厚度进行修正,建立了一种等效厚度模型。将本文提出的等效厚度模型与现有的圆弧模型和线性迭代精确模型应用于算例中进行仿真。结果表明:等效厚度模型更加接近迭代精确值,平均误差率仅为1.37%,其与圆弧模型的平均误差率相比降低了8.35%,一定程度上提高了瞬时未变形切屑厚度的预测精度;在保证了预测精度的前提下,该模型相比于线性迭代模型将瞬时未变形切屑厚度的预测效率提高了10倍以上,在五轴侧铣加工铣削力预测中具有良好的应用前景。

In the 5-axis flank milling force modeling,the calculation of instantaneous undeformed chip thickness(IUCT)is the key link of milling force prediction,which directly affects the prediction accuracy and efficiency of milling force.In order to improve the prediction accuracy and efficiency of milling force,based on the spatial motion analysis of 5-axis machine tools and considering the radial cutter runout effect,a calculation model of IUCT in 5-axis flank milling process was proposed.First,the law of compound motion of milling cutter with tool rotation,swing and translation in 5-axis flank milling process was analyzed,and the coordinate position of each cutting edge at different tool points were obtained.Then,a efficient calculation method of TUCT considering the radial cutter runout effect was presented.Finally,combined with the idea of parameterized thickness compensation,the calculated IUCT was corrected and an equivalent thickness model was established.The equivalent thickness model proposed in this paper with the existing arc model and linear iterative exact model were applied to the simulation example.The results showed that the result of the equivalent thickness model is closer to the iterative exact values,and the average error rate is only 1.37%,decreased by 8.35%compared to the arc model.Under the premise of ensuring the prediction accuracy,the prediction efficiency of IUCT is increased 10 times compared with the linear iterative model.It has a promising application prospect in the establishment of 5-axis flank milling force model.