CAM/CNC走刀轨迹的实时重构

The real-time reconstruction of the cutting path in CAM and CNC

走刀轨迹的优化对复杂型面的高速高精度加工起着十分关键的作用。目前大多数CAM/CNC系统采用大量小直线段逼近原始曲线和直线插补的做法,只能获得零阶连续的走刀轨迹,逼近精度低,不能保证高速加工运动的平稳性,因而加工精度、光洁度和加工速度都难以提高;由小直线段构成的NC代码数据量庞大,也增加了数控系统在内存容量和数据传输方面的成本。本文采用3次参数样条曲线和B样条曲线来实时重构CAM生成的走刀轨迹,以少量的数据点便能达到比直线和圆弧插补高得多的加工精度。文中讨论了数据分段、样条拼接及首尾振荡问题,以及程序实现中的面向对象和多线程技术。在实际使用中显著地提高了数控系统的加工速度和加工精度。

Optimization of cutting path in complex shape machining of CNC machine tools under highspeed and accuracy condition is a crucial problem. The methodology adopted by mostexisting CAM/CNC systems, which uses huge amount of linear segments to approach theoriginal shape and make linear interposition increases the cost of memory size and commu-nication work of the CNC system tremendously. A new approach based on cubic polynomialand B spline interposition to rebuild the CAM generated tool path under real time conditionis presented in the paper. Applications on CNC machine tools showed that the presentedapproach improves the machining accuracy and increases the cutting speed significantly.