| Micro v-groove is widely applied in optoelectronic and microelectronic devices, such as optical fiber connector, wavelength division multiplexer, LCD backlight module, etc. These components are generally processed using special ultra precision machine tools to meet the requirements of optical functional. Through the geometric error compensation to improve the machining precision of the machine tools is the subject of this article. Basing on the micro v-groove ultra-precision machine tools being independent researched and developed, this paper comprehensively analysis the structure of the machine tools and its machining characteristics. The geometric error modeling, measurement and identification of single geometric errors, the polynomial fitting method of single kinematic errors and error software compensation algorithm are the key points of geometric error compensation technology. They are researched through the theoretical calculation and experiment analysis in detail.Accurate error model is the key to achieve error precision compensation. To establish the accurate geometric error model, this paper detailed analysis of the disadvantages of the squareness errors transformation matrix basing on small angle error assumption. On the basis of its disadvantages, the squareness errors transformation matrix is improved. The squareness error which is involved in the improvement of squareness errors transformation matrix is closely calculated. More precision geometric error model is established basing on multi-body system theory, its XFZY configuration and the improved squareness error model and so on. The effect of the improvement of squareness errors transformation matrix is confirmed by comparing the geometric error model being closely calculated before and after.The measurement and identification of geometric errors for CNC machine tools is a complicated and time-consuming work. It is an important topic to fast and accurate measurement and identification the geometric error parameters in the research of error compensation.Nine line identification method for geometric errors commonly used is analyzed in detail. Precision six line identification method which has higher efficiency is proposed for geometric errors. And it is applied in this paper and its reliability is confirmed.The specific geometric error values when the machine moves to a certain position need to be identified in order to facilitate the implementation of geometric error compensation. So these single kinematic errors of machine tools should be fitted to some continuous functions. This paper analyzes the advantages and disadvantages of polynomial fitting method in detail. An optimization method of the polynomial fitted function based on statistical theory is derived. By calculating the geometric error measurement data, its effect is confirmed.Precision compensation of geometric errors is the ultimate aim of the improvement of squareness errors, the measurement and identification of single geometric errors, the optimization of single kinematic errors fitted function and so on. This paper simply introduces the direct calculation method of optimal CNC instruction, and analyzes its disadvantages.The better additional instructions algorithm of CNC correction instruction is studied in detail. By calculating, its effect is confirmed too. |
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