Block processing time-based programming for high-speed, high-precision 5-axis machining

Abstract

For high-speed and high-precision machining with orthogonal 3-axis minute line segment commands, a program should be generated by appropriately reducing the chord error (tolerance) or the block length (line segment length) based on the computer numerical control (CNC) block processing time Tb. The block processing time Tb is the duration from when the CNC decodes one block command in a program until when it controls the motors, depending on the processing power of the CNC. Accordingly, even in simultaneous 5-axis machining, it is necessary to research whether programs generated based on Tb can achieve high-speed and high-precision machining. Therefore, this study aims to realize simultaneous 5-axis machining at higher speed and precision using CNC programs with minute line segment commands based on Tb. In addition, we propose a more general identification method compared with that used in previous studies to identify Tb. Simultaneous 5-axis programs include two cases of control, namely, tool center point (TCP) control and Non-TCP control, and Tb was identified for both controls. For the machining method, using the block length based on Tb, we generated programs to machine the upper flat surface of a workpiece using simultaneous 5-axis machining while rotating the two rotary axes using a ball-end mill. We machined the workpiece and evaluated the machining speed and precision of the machined surface. We showed that simultaneous 5-axis machining with higher speed and precision can be achieved using programs based on Tb. In addition, we analyzed and considered the reasons for the higher-speed and higher-precision machining.