Research On Contour Error Modeling And Cross Coupled Control Method In Multi-Axis CNC Machine Tool

The contour error calculation method directly influences the machining precision in multi-axis CNC machine tool contour error coupled control. Therefore, it is urgent to study high efficiency and high precision CNC machine tools. In the field of modern manufacturing, studying the high-speed and high-precision CNC machine tool becomes the focus of the study. In terms of ultra-precision CNC machining tool, increasing material stiffness or improving assembly accuracy will not meet enterprise’s demand of the precision. Coupling contour error control technique, because of its high cost performance, strong operability and good compensation, is widely used in various fields. The main contents are as follows :(1) Researching from the root of the contour error coupling con trol and based on analyzing the weakness of low calculation precision and insufficient real-time character in conventional machine contour control methods, this paper aimed to free form curves with definition formula, contour error is calculated accurately with dichotomy method and Newton-Raphson method in the paper. Aimed to free form curves with definition formula, a multi-axis contour error calculation model is put forward. The simulation results show that contour error calculation model are calculate-simple and high precision.(2) Traditional PID controller has not the capable of changing parameter value according to the different processing conditions. This has effect on the anti-interference ability of the system. This paper combines the technology of PID control and fuzzy logic control strategy to design a kind of parameter self-adaptive fuzzy logic PID controller. When system encounters abrupt interference, this fuzzy logic PID controller also has satisfactory contour accuracy and better robustness at the same time.(3) In order to meet customer’s demand of contour machining accuracy, this paper uses contour error calculation model, PID controller and fuzzy logic PID controller designed two kinds of contour error calculation model. Both contour error coupled control scheme can realize real-time contour error compensation. The simulation results show that the developed method is effective to improve CNC machine tool contour accuracy.