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.