Papers by Author: Xing Bin Yu

Abstract: The application of ‘small tool’ based on computer controlled is a breakthrough in modern optical machining technology. The unicursal pseudo-random tool path, called “random path” for short, was schemed to reduce the high-frequency errors left by small polishing tool. The clipping algorithm has been developed to optimize random path, thereby it can be used in polishing workpiece surface of any boundary shape efficiently. The power spectral density (PSD) of surface before and after polishing with random path was analyzed and the result indicated that the high frequency error can be reduced by the application of random path.

Abstract: Ultrasonic-magnetorheological combined (UMC) finishing is a new technique for the ultra precision machining of aspheric surfaces, especially for high quality workpieces with small-radius concave surfaces or freeform surfaces. The characteristic of UMC finishing is discussed, and an experimental equipment for UMC finishing with 5 axes is developed. According to requirements of deterministic removal in UMC finishing and the experimental equipment, post processing algorithm for aspheric surfaces is researched. The derivation process and computer simulation result of the algorithm is presented. The error analysis is conducted and the error control method is also proposed. A series of experiments have been conducted, and experimental results show that high quality surfaces can be achieved by the post processing algorithm.

Abstract: Ultrasonic- magnetorheological combined finishing (UMC) is a new technique for the ultraprecision machining of aspheric surfaces, especially for high quality workpieces with small curvature radius concave surfaces. According to the characteristics of UMC finishing, material removal model has been developed. Several types of tool path planning algorithm have been discussed. Two kinds of polyline dwell time algorithm are presented. Polyline Dwell time algorithm based on two-dimensional discrete convolution is a new dwell time algorithm, and the dwell time on the endpoints which compose the tool path can be solved by the algorithm directly. Every polyline dwell time is the mean value of dwell time of two endpoints, therefore, the polyline dwell time of every type of tool path can be solved efficiently by the algorithm. The simulation of two dwell time algorithms has been conducted with same removal function and original error distribution, and the pv convergence rate is improved from 0.939 to 0.973 by using new algorithm. Figure error PV values reduced to 29.4 nm from 1.67μm after UMC finishing. The efficiency of the polyline dwell algorithm is proved by computer simulation and experimental results.

Abstract: Concave aspheric surface with small curvature radius is difficult to fabricate by most of existing technologies. Ultrasonic- magnetorheological combined finishing (UMC) is a new technique for the ultraprecision machining of aspheric surfaces, especially for the ultrasmooth surfaces machining of small-radiuses concave surfaces and freeform surfaces. According to the characteristics of rotary symmetrical aspheric surface, path algorithms for UMC finishing have been developed. Propose and compare two kinds of polishing dwell time algorithms, and the derivation process and computer simulation result of the algorithms was also presented. The experiments using the control algorithm have been conducted, and the efficiency of algorithm is proved by experimental results.

Abstract: Concave aspheric surface with small radius is difficult to be fabricated by most of existing technologies for optical manufacture. Ultrasonic- magnetorheological compound finishing (UMC finishing) is a new technology for the ultra-precision machining of concave aspheric surface with small radius and freeform surface. The principle and experimental deviece used in UMC finishing are introduced. Main technological parameters in UMC finishing include the magnetic flux density, the gap between the polishing tool head and the workpiece, the rotational speed of polishing tool head and so on. The technology experiment of UMC finishing for optical glass K9 is conducted, and the influence of main technological parameters on the material removal rate has been studied by analysis of experimental results. The analysis of removal profile curve of UMC finishing spots prove that the material removal function of UMC finishing meet the surface error convergence requiement in computer control precise optical surface machining. The part surfaces after UMC finishing are measured by an Atomic Force Microscopy (AFM), and the surface roughness Ra is 1.591 nm after polishing for 10 min. It is demonstrated that the polishing capability of the technology is excellent.