An Universal Modeling Method for Enhancing the Volumetric Accuracy of CNC Machine Tools

Volumetric error modeling method is an important te ch nique for enhancement the accuracy of CNC machine tools by error compensation. I n the research field, the main question is how to find an universal kinematics m odeling method for different kinds of NC machine tools. Multi-body system theor y is always used to solve the dynamics problem of complex physical system. But t ill now, the error factors that always exist in practice system is still not con sidered. In this paper, the accuracy kinematics of MBS (multi-body system) are developed by adding the movement error items and the positioning error items for every couple of adjacent bodies. After make an analysis for different kinds of NC machine tools we can find that NC machine tools can be looked as a kind of sp ecial MBS. It’s main construction only contains two movement branch. the one is from base part to workpiece and the other is from base part to cutter. So an u niversal volumetric error modeling method and the error analysis method for NC m achine tools can be built in this paper based on MBS theory. The essential condi tion for precision machining is derived through mathematics equations and the co ncept of ICCP (inverse changed cutter path ) and ICNI (inverse changed NC instru ction ) are presented in this paper. The numerical solution methods for ICCP and ICNI are also given in this paper which can be directly used to enhance the mac hining accuracy of NC machine tools. In order to verifying the above works, the double frequency laser interface detecting instrument of RENISHAW is used to mea sure the error parameters of the MAKINO 3-axis NC machine tools and the softwar es are developed using C++ developing language to simulate the cutte r trail under different kind conditions in the computer. Latterly the standard w ork parts are selected to be machined on the MAKINO 3-axis NC machine tools bef ore and after use the above mentioned error compensation method respectively. Th e simulation and experiment results show that the volumetric error modeling meth od is effective and the machining accuracy of CNC machine tools can be improved more than 60% after using the compensation method presented in this paper.