Research On Error Modeling And Experimental Analysis For Freeform Surface Turning System

The characteristics of freeform surface are irregular and changeable, which makeit not only has good optical performance, but also can reduce the size of optical part,so that the innovative design of the optical system becomes possible. It’s also basedon this characteristic, freeform surface draws attentions and plays a vital role inadvanced science fields like aerospace and military. Since then, due to its outstandingperformance, freeform surface gains recognition quickly and has been widelyresearched and applied in many other fields such as optics, automotive, electronics,shipbuilding, medical, etc. As for freeform surface manufacturing, diamond turning,based on fast tool servo (FTS) system, is precision and efficient. It is one of the mostpromising methods and mature processing technology. However, because of thecomplicated surface shape features and the higher quality requirements in applications,the processing of freeform surface is still a difficult problem. Even the most advancedprocessing method may cause manufacturing error inevitably. Therefore, the researchon errors of freeform surface manufacturing system is especially meaningful. Basedon that, this paper discusses these problems in depth.First of all, this essay summarizes the possibly original errors of NC machines,and analyzes their advantages and disadvantages. Simultaneously, the errorcomponents of the triaxial diamond lathe with fast tool servo used in the study arediscussed. What’s more, the main factors of the errors (including geometric error,thermal error and dynamic error) are described and significant efforts are placed intothe impact of the above kinematic error and thermal error to the freeform surfacemachining accuracy. Then, combine with the characteristics of diamond turning basedon FTS, this paper roughly analyzes the main causes of the dynamic error. Last butnot least, the comprehensive error model of triaxial diamond lathe is established in the study, in which homogeneous transformation is adopted to build the heat error andgeometrical error model that occupy more than70%of the overall error. Ultimately,the kinetic model of FTS is built by real-time analysis of the cutting force disturbanceon the system.Laser interferometer is used to measure and identify the error components on theX-directional slide in order to analyze their characteristics of distribution. Meanwhile,by combining the obtained data with the error model, the component characters of theerrors of cutting tool coordinate system relative to workpiece coordinate system areanalyzed along the X, Y, and Z axis. Experimental results indicate that the geometricerrors of machine are stable and repeatable. Finally, the method using FTS tocompensate error is proposed in the article.The research on error modeling and experimental analysis for freeform surfaceturning system in this paper lays a foundation for the further research on tool pathplanning of freeform surface’s diamond turning and precision machine’s errorcompensation.