基于切削力预测模型的复杂曲面铣削进给速度优化

Feedrate optimization of complex surface milling based on predictive model of cutting force

针对复杂曲面恒定进给速度带来加工效率低下及表面质量差的情况,提出了基于切削力预测模型的铣削进给速度优化方法.首先,通过对刀位轨迹、曲面与刀具几何、刀/工切削接触区及动态切削厚度的分析计算,建立了多轴加工复杂曲面的切削力预测模型,从而得到了进给速度与切削力之间的映射关系.然后将给定的参考切削力与每个刀位点处的最大切削力之差的绝对值作为优化目标函数,通过Newton-Raphson迭代算法来调整原刀位点文件中的进给速度,以确保切削力的恒定以及机床系统的运行平稳.最后,以模型桨桨叶为对象,开展了相应的加工实验.实验结果表明:提出的优化方法使桨叶精加工的时间缩短了25%以上,表面残余应力和显微硬度得到增加,这对提高桨叶曲面的加工效率与改善加工表面质量具有明显的效果,从而验证了所提出的进给速度优化方法的有效性.

In terms of the low machining efficiency and bad surface quality using constant feedrate in complex surface milling, a feedrate optimization method is proposed based on cutting force model. Firstly, by the analysis and calculation of the tool path, the geometry of complex surface and tool, tool-workpiece engagement zone and uncut chip thickness, a cutting force model is derived in multi-axis maching of complex surface and the mapping relation is obtained between feedrate and cutting force. Then the objective function about the absolute value of difference between the reference cutting force and the maximum one calculated in each tool position is put forward. Then the method adopts Newton-Raphson iteration algorithm to alter the feedrate in the original tool path file, thus ensures the constant cutting forces and enhance steadiness of machining process. The experiment is carried out about model propeller, the results show that the proposed optimization method ensures the machining time of the blade reduced by more than 25%, the surface residual stresses and micro-hardness machining accuracy to be increased, which has a clear effect on increasing the machining efficiency and improving the machining surface quality of the blade. This thus validates the effectiveness of the proposed optimization method.