Multi-axis synchronous interpolation feed rate adaptive planning with rotational tool center point function under comprehensive constraints

Abstract

Real-time nonlinear error caused by rotation axis motion in five-axis interpolation can be compensated by rotational tool center point function. It is well known that reduction of the interpolation nonlinear error can be achieved effectively by increasing the interpolation steps, but what the value of the steps' number should be has rarely been mentioned in the existing literature. Taking a five-axis interpolation machine tool with B & C swing axis as an example, the real-time planning and controlling for the integrated feed rate of a five-axis interpolation is proposed by analyzing mechanism of the nonlinear error in the interpolation with rotational tool center point function. The nonlinear error and its derivative of the swing axis are derived. Then, a S-shape feed rate real-time planning and control method about curve interpolation is present first, and then considering the restrictions of the tool axis motion by the feed axis' mechanical properties and the cutting characteristics, the most appropriate interpolation step length in a single interpolation cycle is calculated in real-time. It shows that comparing to approach with no rotational tool center point interpolation error control, the interpolation error acquired by rotational tool center point in proposed approach can be further reduced while ensuring the smooth and safe machining of the machine tool, and the surface quality of workpiece is also greatly improved.

Regionalized compensation method for nonlinear error control

“…For example, Hang et al [16] verified the effectiveness of the RTCP method through MATLAB simulation to analyze the kinematics of a double-turntable five-axis machine tool. Shi et al [17] implemented real-time interpolation planning for five-axis maximum feed speed based on RTCP algorithm, and the experimental results showed that this method can effectively improve the surface quality of parts. Although the RTCP algorithm can effectively control nonlinear error, its implementation method is very expensive because it involves an advanced NC system.…”

Triple parametric tool path interpolation for five-axis machining with three-dimensional cutter compensation

“…Wang et al 16 implemented the five-axis transformation function in a conventional CNC system for five-axis G1 tool path interpolation. Zhou et al [17][18][19][20] proposed an adaptive feedrate interpolation with multi-constraints for five-axis parametric tool path. However, the aforementioned works did not implement or consider the five-axis parametric interpolation command format, five-axis parametric interpolation strategy, five-axis transformation function, and 3D cutter compensation in the same time, thus none of them can be applied to real machining applications.…”