基于Hermite插值的复杂光学曲面车削加工路径规划

为解决复杂光学曲面加工难题,探讨其车削加工路径规划。基于慢刀伺服加工技术对复杂光学曲面的刀位点规划进行设计,分析刀触点等角度离散方案及刀具圆弧半径补偿方案。轨迹插补采用可编程多轴控制器(Programmable multi-axiscontroller,PMAC)提供的位置、速度、时间(Position velocity time,PVT)插补运动模式,分析PVT的数学实质Hermite分段插值模型,并根据此模型提出恒速法、面积法和三点法三种PVT入口参数生成算法。以离轴抛物面、环曲面、正弦面为例进行仿真,加工路径的仿真表明刀位点的设计可以应用于复杂光学曲面加工。同时z轴运动特性的分析表明z轴往复频率和C轴回转频率相仿时,面积法(c=2/3)和三点法均能满足z轴速度光顺要求;z轴往复频率明显大于主轴频率时,采用三点法的加速度变化明显优于面积法。提出的加工路径方法可为复杂光学曲面的实际加工提供指导意义。

Cutting Path Planning for Complex Optical Surface Using Hermite Interpolation

The cutting path planning is discussed in order to solve the difficulties of processing complex optical surfaces.Cutter location point(CL) planning is designed,cutting contact point(CC) discretization and cutting tool compensation are analyzed based on slow tool servo.Based on programmable multi-axis controller(PMAC),Hermite segment interpolation is analyzed which is used by trajectory interpolation,and three position velocity time(PVT) entrance parameters algorithms are putted forward,the constant speed method,the area method and the three points method.The simulation of cutting path of off-axis parabolic,toric and sinusoidal surfaces shows that the design of CL can be used to complex surfaces processing.Meanwhile,the analysis of z axis motion characteristics shows that area method(c = 2/3) and three points method both can meet the requirements of smooth velocity of z axis when z axis reciprocating frequency is similar to C axis rotary frequency.And three points method is better than area method in the change of acceleration when z axis reciprocating frequency is significantly greater than C axis rotary frequency.The proposed method affords benefit for practical manufacturing of complex optical surfaces.