Papers by Author: Jing Feng Zhi

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Authors: Xun Chen, Jing Feng Zhi, I.R. Pashby
Authors: Ke Xin, Wei Zuo, Jing Feng Zhi
Abstract: A novel quantitative shadow testing equipment is presented based on the digital imageprocessing technique for characterizing local surface deformations on optical surface. Two magnetic stepping motors control the positions of the knife-edge for cutting the wave-front reflected back from the aspheric surface separately. At each position of the knife-edge blocking the image on the focal plane, it is recorded and analyzed by an image-processing set-up behind the knife-edge under computer control. Based on a group of images recorded, the analysis of local slopes is performed by picking up characteristics of illumination levels. Further the relationship between the changes of illumination level and deformations on surface is built on the principle of Fourier Optics. The results of tests approve that the method is effective on determining the characteristics of two parabolic surfaces using magnetorheological finishing.
Authors: Xun Chen, Jing Feng Zhi, I.R. Pashby
Authors: W. Zuo, Jing Feng Zhi, S.T. Huang, G.M. Zhao
Abstract: This paper presents an electronic subdviving method for linear encoder of high speed position detection. The method aims to enhance the resolution of position measurement and improve the precision of noncircular component cutting system. A 20-subdividing circuit based on resistor chain phase shift is researched and implemented, and some key technologies are discussed. The method is proved to be successful in raising the resolution and precision with a high speed response. The experiment result proves that electronic subdividing method is doable and effective to raise the resolution of the existing system.
Authors: Hao Bo Cheng, Jing Feng Zhi, Suet To, Yong Tian Wang
Abstract: This paper proposes a novel wheel-shaped grinding/polishing tool, which is designed to be controlled on both the self-rotation around its axis and the co-rotation around vertical axis Z at the specified speeds respectively. Therefore, the surface material of the workpiece can be removed by virtue of self-rotating motion. On the other hand, the co-rotating motion will also change the manufacturing orbit continually. To analyze the characteristics of the tool, material removal in the manufacturing zone on the workpiece surface is first established through theoretical modeling. Subsequently, a good evaluating method, i.e. power spectral density, for analyzing the frequency spectrum features of material removal function in computer-controlled optical grinding and polishing is introduced in detail. By simulation, the power spectral density of the material removal function was cut into several parts, some frequency with low amplifies of material removal function were removed, and the modified material removal function reflected the actual processing status, which was helpful in removing some residual high frequency errors on the surface of the workpiece. Finally, the high amplitude such as at high frequency of 110mm-1 and 210mm-1 was reserved and some other low amplitude frequencies were removed.
Authors: Xing Zhu Xu, Zhang Yun, Yue Wang Yu, Jing Feng Zhi
Abstract: Most present methods of determining optimal fitting spherical surface for rotationally symmetrical aspheric optics are either unsuitable for off-axis optics or unable to guarantee “the condition of positive removal” (distances from points on desired concave aspheric surface to the center of fitting sphere are all longer than radius of sphere while distances from points on desired convex aspheric surface to the center of fitting sphere are all shorter than radius of sphere). To surmount the two problems, this paper proposes three methods of determining starting spherical surface in finishing/polishing aspheric optics: method of using the function of “lsqlin” provided in Matlab, the modified method of least squares and the method of exhaustive search of tangent spheres. An example is presented to validate the three methods and to demonstrate all of them gain some advantages over conventional one by comparing attributes (normal deviation distribution, maximum normal deviation, volume of material to be removed, rms of normal deviation distribution, etc.) of their optimal fitting spheres against those of sphere obtained by utilizing conventional method.
Authors: Yong Bo Wu, Mitsuyoshi Nomura, Jing Feng Zhi, M. Kato
Abstract: This paper discusses the mechanism behind the grinding force decrease associated with ultrasonication of the grinding wheel in constant-depth-of-cut ultrasonically assisted grinding (UAG). By introducing a grinding model describing the cutting trace of an abrasive grain, an equation relating the grinding force decrease to such process parameters as the amplitude and frequency of vibration and the grinding wheel speed, is established. Experiments are conducted to confirm the theoretical prediction. Theoretical and empirical results both indicate that the decrease in grinding force is due to the grinding chips becoming smaller and fracturing more easily under ultrasonication. The results also suggest that the grinding force decrease is greater at higher vibration amplitudes and at lower grinding wheel speeds.
Authors: Yun Zhang, Jing Feng Zhi, Yong Bo Wu
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