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Tool Orientation Optimization Based on Spatial Tractrix Method for Five-Axis CNC Machining with Ball End Cutters

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Communications in Mathematics and Statistics 2022年第4期10卷 705-737页

作者： Xiang Zou Ke Shi Hai-Yin Xu hon-yuen tam School of Computer Science and Technology Huazhong University of Science and TechnologyWuhanPeople’s Republic of China Department of Mechanical Engineering College of Science and EngineeringCity University of Hong KongKowloonHong KongPeople’s Republic of China

When milling part surfaces with a ball-end tool in 5-axis CNC machining,maintaining a constant cutting speed by keeping a fixed inclination angle between the tool axis and surface normal is crucial to ensure safe operation and achieve high quality of the machined *** this constraint,the variation of tool orientation is expected to be“smoothest possible”to reduce the angular speed of the rotary axes for the efficient and robust *** address this issue,the spatial tractrix which is the extension of classic tractrix is presented to establish the geometry model of the tool orientation kinematics in the part coordinate *** proposed model describes the relations between the tilt angle and the variation of ball-end tool *** spatial tractrix-based methods,synchronizing tractrix-based method and equilibrating tractrix-based method,are developed to minimize the variation of tool orientation by controlling the variation of tilt *** methods are used to plan the tool orientation on a part surface modeled by a bicubic spline *** performance evaluation carried by intense simulations demonstrates the equilibrating tractrix-based method provide the best results in most cases compared with the existing differential geometry-based methods such as the tractrix-based method and parallel transport *** synchronizing tractrix-based method works well in some special cases.

关键词： Five-axis machining Ball-end tool orientation Spatial tractrix Tool orientation optimization

Edge effect of optical surfacing process with different data extension algorithms

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Frontiers of Optoelectronics 2014年第1期7卷 77-83页

作者： Yang LIU Haobo CHENG Zhichao DONG hon-yuen tam School of Optoelectronics Beijing Institute of Technology Beijing 100081 China Department of Mechanical and Biomedical Engineering City University of Hong Kong Hong Kong China

This study presents a strategy which integrates extra polishing path （EPP） and error map extension to weaken the edge effect in the ultraprecise optical surfacing process. Different data extension algorithms were pre- sented and analyzed. The neighbor-hood average can be selected as the frequently-used method, as it has not bad precision and time-saving performance for most surface forms through the simulation results and practical experi- ment. The final error map was obtained, its peak-to-valley （PV） was 0.2732 and root mean square （RMS） was 0.0282 （2 = 632.8nm）. The edge effect was weakened and suppressed well through the experiment.

关键词： edge effect convergence rate extensionalgorithms

Design of integrated-electrode tool for electrorheological finishing of optical glasses

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Frontiers of Optoelectronics 2011年第4期4卷 467-471页

作者： Binbin CHEN Haobo CHENG hon yuen tam Hui LI School of Optoelectronics Beijing Institute of Technology Department of Manufacturing Engineering and Engineering Management City University of Hong Kong

Electrorheological(ER) finishing utilizes the flow of electrically stiffened abrasive fluid through a preset converging gap formed by the work-piece surface and a moving tool. An ER finishing tool characterized by cathode integrated with anode together is proposed,whose electric field distribution is finite-element-analyzed(FEA) and is useful to finish both conductive work-piece and non-conductive ones. Experiments were performed to finish a K9 glass by this tool. After 30 minutes polishing,the surface roughness was reduced from 8.46 to 2.53 nm Ra which is better than previously reported 2.9 nm. The result verified the validity of the integrated-electrodes tool for non-conductive optical glasses.

关键词： electrorheological (ER) finishing roughness material removal

Measurement of optical mirror with a small-aperture interferometer

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Frontiers of Optoelectronics 2012年第2期5卷 218-223页

作者： Ya GAO hon yuen tam Yongfu WEN Huijing ZHANG Haobo CHENG School of Optoelectronics Beijing Institute of TechnologyBeijing 100081China Department of Manufacturing Engineering and Engineering Management City University of Hong KongHong KongChina

In this paper, the principle of subaperture stitching interferometry was introduced. A testing stage with five degrees of freedom for stitching interferometry was built. A model based on least-squares method and error averaging method for data processing was estab- lished, which could reduce error accumulation and improve the precision. A 100ram plane mirror was measured with a 50mm aperture interferometer by means of stitching interferometry. Compared with the results by a 100 mm interferometer, peak to valley （PV） and root mean square （RMS） of the phase distribution residual are 0.00382 and 0.00042, respectively. It proved that the model and method are helpful for large optical measurement.

关键词： subaperture stitching interferometry residualerror

Error compensation for three-dimensional profile measurement system

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Frontiers of Optoelectronics 2015年第4期8卷 402-412页

作者： Xu YE Haobo CHENG Zhichao DONG hon-yuen tam School of Optoelectronics Beijing Institute of Technology Beijing 100081 China Department of Mechanical and Biomedical Engineering City University of Hong Kong Hong Kong China

Three-dimensional （3D） profile measurement is an indispensable process for assisting the manufacture of various optic, especially aspheric surfaces. This work presents the measurement error calibration of a 3D profile measurement system, namely PMI700. Measurement errors induced by measuring tool radius, alignment error and the temperature variation were analyzed through geometry analysis and simulation. A quantitative method for the compensation of tool radius and an alignment error compensation model based on the least square method were proposed to reduce the measurement error. To verify the feasibility of PMI700, a plane and a non-uniform hyperboloidal mirror were measured by PMI700 and interferometer, respectively. The data provided by two systems were high coincident. The direct subtractions of results from two systems indicate RMS deviations for both segments were less than 0.22.

关键词： aspheric surface three-dimensional (3D) pro-file measurement alignment error error compensation

Profile and roughness of electrorheological finishing optical surfaces

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Frontiers of Optoelectronics 2015年第3期8卷 306-313页

作者： Haobo CHENG Jingshi SU Yong CHEN hon-yuen tam School of Optoelectronics Joint Research Center for Optomechatronics Design and Engineering Beijing Institute of Technology Beijing 100081 China Department of Mechanical and Biomedical Engineering City University of Hong Kong Hong Kong China

This paper focuses on the process of electrorheological （ER） finishing optical surfaces. Experiments on K9 mirrors were conducted. In one experiment, the operating distance was varied over 0.5-0.8 mm with the voltage at 2000 V. The maximum peak-to-valley （PV） reduction was obtained at the distance of 0.5 ram, where the PV value was reduced from 58.71 to 25.03nm. In another experiment, the voltage was varied over 1500- 3000V with operating distance at 0.5mm. The final surface roughness （Ra） achieved was as low as 2.5 rim. A higher voltage produced a higher relative reduction of the Ra. These experimental results validated the process.

关键词： electrorheological (ER) finishing surface roughness

High precision mode of subaperture stitching for optical surfaces measurement

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Frontiers of Optoelectronics 2013年第2期6卷 167-174页

作者： Huijing ZHANG Haobo CHENG hon yuen tam Yongfu WEN Dongmei ZHOU School of Optoelectronics Beijing Institute of Technology Beijing 100081 China Department of Mechanical and Biomedical Engineering City University of Hong Kong Hong Kong China

Subaperture stitching （SAS） provides us with an attractive way of extending the effective aperture and dynamic range of phase measuring interferometers. Accuracy of stitching algorithm becomes the key factor in the SAS technology. In this paper, the basic principle of SAS was introduced and four modes of SAS were discussed. The stitching experiments were done through the SSI-300 workstation designed and developed indepen- dently. There were several comparisons between the four different stitching methods and the measurement of full aperture. The results suggest that the global error averaging mode with reference of subaperture near optic axis is of high precision.

关键词： optical testing subaperture stitching (SAS) algorithm stitching mode

Nucleoside modified mRNA-lipid nanoparticles as a new delivery platform for the repair of the injured spinal cord

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Neural Regeneration Research 2025年第8期20卷 2311-2312页

作者： Krisztián Pajer tamás Bellák Antal Nógrádi Department of Anatomy Histology and EmbryologyAlbert Szent-Györgyi Medical SchoolUniversity of SzegedSzegedHungary

Spinal cord injury and treatment opportunities:The adult mammalian spinal cord has a very limited capacity for spontaneous regeneration due to various intrinsic molecular and cellular *** the spinal cord neurons have the capacity to regenerate their axons,the expression of growth inhibitory factors,lack or suppression of proper guidance cues,and profound inflammatory responses do not permit successful regeneration(Khyeam et al.,2021).

关键词： injured capacity modified

Generation of Nonlinear Evolution Equations by Reductions of the Self-Dual Yang–Mills Equations

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Communications in Theoretical Physics 2014年第2期61卷 203-206页

作者：张玉峰 hon-Wah tam College of Sciences China University of Mining and Technology Department of Computer Science Hong Kong Baptist University

With the help of some reductions of the self-dual Yang Mills(briefly written as sdYM) equations, we introduce a Lax pair whose compatibility condition leads to a set of(2 + 1)-dimensional equations. Its first reduction gives rise to a generalized variable-coefficient Burgers equation with a forced term. Furthermore, the Burgers equation again reduces to a forced Burgers equation with constant coefficients, the standard Burgers equation, the heat equation,the Fisher equation, and the Huxley equation, respectively. The second reduction generates a few new(2 + 1)-dimensional nonlinear integrable systems, in particular, obtains a kind of(2 + 1)-dimensional integrable couplings of a new(2 + 1)-dimensional integrable nonlinear equation.

关键词： self-dual Yang-Mills equation Lax pair (2+ 1)-dimensional integrable system integrable coupling