基于最小切削时间的加减速规划与控制

切削过程的加速控制不仅影响切削加工的效率,同时也会产生加工过程的冲击、过切和振荡,影响加工对象的轮廓精度.本文在分析高速切削加工特点和基本要求的基础上,提出一种全新的加/速控制策略,它可在PMAC多轴运动控制器所构造的CNC数控系统环境下,首先对NC加工程序进行预处理,针对各程序段之间的几何关系对各切削加工程序的加速进行规划,根据伺服电机所允许的最大动态扭矩选取最大加速度,计算各控制轴加速时间常数,修改原有的NC程序,从而达到最短切削时间加减速控制的目的.

Planning and Control for the Acceleration and Deceleration of CNC Machine Tool Based on Minimum Time Cutting

With the development of metal cutting towards high-speed and high-precision trend, the control for acceleration/deceleration (Acc/Dec) of CNC machine tool during cutting process has been becoming increasingly important. Perfect Acc/Dec control strategy not only makes cutting process more efficient, but reduces the impact, over-cutting and disturbances during the process, which improves the work-piece's contour precision. After discussing the characteristics and basic demands of high-speed cutting this paper proposes a novel Acc/Dec control approach, which is supported by CNC system based on PMAC(Programmable multi-axis controller). This approach predetermines NC program, analyses the demanded contour specified in the G-code file and generates an efficient Acc/Dec planning. Then according to the dynamic torque limit that the amplifier and servo motor can be stand, the maximum acceleration and each axis acceleration interval are calculated. Finally, the original NC program is modified in order to minimize the cutting time. This paper consists of four sections: In section 1, the basic characteristics and demands of Acc/Dec control during high-speed cutting are discussed. The idea of Acc/Dec control approach based on minimum-time cutting is presented in section 2. And in section 3, the method for predetermining the NC program and calculating the Acc/Dec interval is discussed. Finally in section 4, we draw a conclusion by assessing this appwach's results.