Real-Time Geometric And Thermal Error Compensation Of CK6430 Lathe

The paper introduces the methods of integrated error modeling and error elements measurement of CK6430 CNC lathe, the development of a new generation compensation device of integrated error, and the real-time application of it. The main content includes the following aspects:(1) The integrated error model of CNC lathe is built through the error source analysis of the components, using the closed characteristic of the linking loop between the tool and work piece, and homogeneous coordinate transformation. The model includes both the two significant error elements, geometric error and thermal error, and is the basis of error measurement and real-time error compensation.(2) The integrated geometric positioning error models of each axis is built. Relationship between positioning error and temperature is found through analysis of positioning error curves with different temperature. Next, using correlative analysis, the most significant temperature variables associated with positioning error are found. Last, the integrated geometric positioning error is built through polynomial regression method. Thermal effect on geometric positioning error is considered. The accuracy and robustness of the model are validated by experiments.(3) In order to improve the accuracy of thermal error model, a method based on optimum selection of time series models is presented, and how to select the time series models is discussed in detail. Through analyzing ACF and PACF of the thermal error series, the type of time series model was identified first, and then the order is determined by AIC, F and whiteness examining. The analysis of time series is completed by PASW software. In contrast with another modeling method, the model is confirmed to have a higher precision.(4) The paper develops a new generation compensation device of integrated error of CNC machine tools, based on the principle of extended outside mechanical origin function of FANUC CNC system. The compensation principles, and the structure of hardware and software, are analyzed specifically. Last, according the error models and measured error data, using the error compensation device, the real-time geometric and thermal error compensation are executed on CK6430 lathe. Good compensation effects are acquired through comparison.