Study On The Technology Of Software Compensating For The Geometric Errors Of NC Machine Tools

There have two types of methods to improve the geometric precision of machine tool: Error Avoidence and Error Compensation.Using software technology,Error Compensation can enhance the precision not only for the new machine tool but also the used machine tool, and can be realized easily using low cost.In recent years,many researchers have devoted a great deal of effort to this work,and progress has been maken in certain aspect.However, some problems,such as modeling of geometric errors between cutter and workpiece, fast measurement and identification of original errors,compensation of spatial geometric errors,have not been solved well.This thesis has carried out an in-depth study aiming at these problems and it lays the strong emphases on the researches of the error analyzing and predicting, software error compensating and so on. acquired the follow main achievements:At first, the commonly used measurement of the parallel machine and corresponding measure tool were studied. The measurement theory and application methods of some advanced measure instrument were analyzed, which are DBB (double ball bar); the dual frequency laser interferometer.After establishing the precision model of machine tools, the measurement and evaluation of their error parameters have been started. There are many kinds of error parameters in a machine tool to influence its machining accuracy. this paper gives a systematic and in-depth study on the MBS kinematics theory and the methods of precision modeling, error identification, accuracy prediction, and error compensation based on the studied theory. this paper has detailed fourteen-line method, probed into a new method defined as twelve-line method for the sake of making the most of double-frequency laser interferometers to measure and evaluate 21 geometric errors of three-axis system.A key point of software error compensation is that how to obtain the numerical control instructions to compensate the known errors. The software is compiled with VC. the dynamic compensation methods of geometric errors are integrated in Huazhong CNC. the experiment system of geometric errors compensation for CNC machine tool is built.In this system,experiment validation of localization motion errors is realized. three axes are also validated by experiment.Experiment results show that the model of geometric errors,measurement methods of machine tool original errors and the compensation scheme of spatial geometric built by this paper are effective.