Papers by Keyword: Precision Grinding

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Authors: Zhen Yuan Jia, T. Ji, Dong Ming Guo, Gui Hong Bian
Authors: Ning Ning Zhang, Chen Jiang, Zhen Zhong Wang, Yin Biao Guo
Abstract: Large scale wedge/aspheric lens element is a combination of wedge prism and aspheric lens as a single piece component forming a decentred lens, which is primarily manufactured by Computerized Numerical Control (CNC) machining, especially 3-axis CNC grinding. This paper presents an efficient tool path generation approach based on isophote interpolation. The interpolation guarantees that interpolated points always stay on the iso-inclination curve of the parametric surface. This symmetry ensures that the method can improve and automate large scale wedge/aspheric lens element machining for 3-axis CAD/CAM systems. As part of the validation process, the tool paths generated are analyzed and compare with the desired part.
Authors: Jin Kai Xu, Hua Dong Yu, Xue Jun Zhang
Abstract: This paper introduces the affecting factors of tool clamping error of the axis direction in aspheric manufacturing process, and analyses the effects of tool clamping errors of the wheel along X and Y directions on processing area and contour error curve in depth in the aspheric manufacture parallel grinding, and calculates the relationship between tool clamping error of axis direction and aspheric shape error, and applies the theory in the machining process. The experiments show that the processing time decreases by 60% with satisfactory precision. The surface accuracy of 0.15 μm (0.237λ) of PV value and 0.023 μm (0.036λ) of RMS value can be achieved for 51.5 mm diameter aspheric surfaces. The theoretical analyses and error compensation methods are validated through the experiments, and the results show that the rapid process of aspheric surfaces can be realized.
Authors: Xiao Long Ke, Yin Biao Guo, Chun Jin Wang
Abstract: According to the demand of precision machining for optical aspheric lens, especially large scale optical aspheric lens, this paper presents an error compensation technique for precision grindging. Based on precision surface grinding machine (MGK7160), grating-type parallel grinding method is put forward to realize grinding paths planning for optical aspheric lens. In order to obtain surface metrology and evaluation after grinding, an on-machine measurement system is built. On the basis of compensation principle, machining error is separated to achieve error compensation. Grinding experiments are carried out and show that it can meet the demand of precision grinding, and the accuacy after error compensation attains 6.5μm.
Authors: X.L. Zhu, Z.G. Dong, Ren Ke Kang, D.M. Guo
Abstract: This study presents design of an ultra-precision wafer grinder which incorporates state-of-the-art automatic supervision and control system. The wafer grinder is characterized by wafer surface shape control, grinding forces and wafer thickness monitoring systems. The design provides a totally integrated solution to the ultra-precision grinder that is capable of grinding silicon wafers with surface roughness Ra<3 nm and total thickness variation<2µm/300mm.
Authors: Guo Bi, Yin Biao Guo, Kun Pan, Chen Jiang
Abstract: Minute vibration of grinding wheel greatly restricts machining accuracy of axisymmetric aspheric surface in precision grinding. This paper is dedicated to analysis micro-topography of grinding surface under grinding wheel vibration. The relative motion track of wheel to ideal lens surface and the interference of them are involved to study the effects of grinding wheel vibration on surface quality. For different operation parameters, the processed surface presents various micro-topography, and the restriction extent of vibration to surface quality is also different. Vibration waveform in the region near lens center is smoothed greatly by the interference of wheel and the processed surface. Therefore, surface quality gets some improvement from edge to center for axisymmetric aspheric lens. Experiment results verified the validity of the theoretical analysis.
Authors: Cheng Zu Ren, J.M. Che, Tai Yong Wang, W.D. Jin, Xin Min Jin
Abstract: The state of the passivating film is a key factor affecting ELID grinding. In the paper the state of the passivating film on the grinding wheel surface was characterized by the loop current, the strategies actively controlling the film state, discontinuous in-process electrolyzing and intermittent grinding were put forward, and the ELID grinding tests under the conditions of actively controlling of the film state and the traditional dynamic balance of the film state were respectively performed and contrasted with each other. It is indicated that by real-time monitoring of the film state with the loop current, the film state variation could be controlled to a narrow scope with the strategies of discontinuous in-process electrolyzing and intermittent grinding, as a result the ELID grinding kept at a fine quality and a high efficiency.
Authors: Zhen Zhong Wang, Yin Biao Guo, Jiang Guo, Qiao Xu
Abstract: In precision measurement, the existed error of measuring system influences surface accuracy more. This paper provides an error analysis focusing on the research effort on aspheric lens on-machine measurement for form accuracy. And the error parameters including positioning error of coordinate origin, tilt angle and radius error of probe head are investigated. It was known that it was quite difficult to obtain the parameters by detecting instruments, so the method of error separation and correction based on measuring standard parts is presented in this paper to guide the inverse solution for higher measuring accuracy. Also, a measuring experiment with Φ210mm lens is executed. Experimental results indicate that the method based on standard parts is suitable for on-machine precision measuring of aspheric lens.
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