自由曲面等误差数控加工刀轨生成方法

Iso-error NC Machining Tool Path Generation Method for Free-form Surface

等误差刀轨的逼近误差等于设定的最大允许值(阈值),步长达到了理论最大,能够有效提高数控加工的进给速度和平顺性,为了对自由曲面高效地生成满足精度要求的等误差刀轨,提出以几何距离驱动刀触点调整的等弓高误差刀触点迭代搜索方法,提出以刀具切削包络面与刀触点轨迹线之间的最大距离作为逼近误差、采用自适应离散法进行计算的方法;然后以等弓高误差刀触点的刀位点作为初值,提出步长自适应调整迭代的等误差刀位点计算方法;最后对算例计算出等误差刀轨验证了算法的可行性,所有刀位点的逼近误差均位于指定的阈值邻域内,满足了等误差要求,与常用的步长筛选法相比,计算时间更短、刀位点更少。

Step errors in iso-error tool path are equal to the set maximum allowable value(threshold value).The step sizes are the theoretical maximums,which can improve the feed speed and smoothness of numerical control(NC)machining effectively.In order to generate precise iso-error tool path for free-form surface efficiently,an iterative search method is proposed to adjust constant chord error cutter contact(CC)points by geometrical distance.The maximum distance between the tool cutting envelope surface and the tool contact trace line between adjacent tool points is proposed as the step error.A self-adaptive discrete method is used to calculate the step error.And then,taking the cutter location(CL)points of constant chord error CC points as initial points,a self-adaptive step adjusting method is proposed to calculate the iso-error CL points.Finally,iso-error tool path is generated for an example surface,which verifies the feasibility of the algorithm.All the vales of step error in the iso-error CL points are in the set neighbourhood of threshold value,which meets the iso-error requirement.Compared with common step screening method,the computing time is shorter and the CL points are less.