五轴加工奇异区域内的刀具路径优化

Tool Path Optimization of Five-axis Machining in Singular Area

针对五轴加工在奇异区域内由于旋转轴运动的剧烈变化导致非线性误差过大并对工件、刀具和机床部件造成损害等问题,给出一种奇异区域内加工路径的优化方法。以AC双转台五轴联动数控机床为研究对象,在反向运动学变化中根据正弦、余弦三角函数的周期性对C轴转角进行初次优化;按照加工是否通过奇异点两种情况,采用设定奇异点处的C角值或者修改奇异点附近的刀轴方向两种方法,进一步降低C轴过大转角;以当前加工区间的非线性误差是否超过允许值为判断条件,对仍然不满足精度要求的区间进行递归插值处理。仿真试验和实际加工结果表明,与单纯采用线性插值方法相比,该方法在提高奇异区域内加工精度的同时,有效减少新插入点的数量,从而尽量降低加工速度的损失。

To solve problems of too large non-linear error and damages to the workpiece,the cutter and the machine tool caused by drastic motion of the rotational axis in singular area,an algorithm that optimizes the tool path of five-axis machining in singular area is proposed.Consider a table-tilting type machine tool with two rotational axes A and C.The initial optimization for C angle based on the periodicity of sine function and cosine function proceeds.Based on judging whether the tool passes the singular point,there are two ways to decrease too large rotation of C axis further.The one is setting the value of C angle at the singular point.The other is modifying the direction of tool axis near the singular point.The intervals whose non-linear errors still exceed the allowed range are interpolated recursively.The experiment is performed to test that the rapid motion of axis in singular area is effectively prevented and the non-linear error is largely reduced by such method.Simultaneously,compared with the method just using linear interpolation,the number of interpolated points is fewer and the processing speed is faster via such method.