Ultra-Precision Machining Technologies, CJICUPM2008

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Authors: Ju Long Yuan, Zhi Wei Wang, Miao Qian, Dong Qiang Yu
Abstract: This paper analyzes the property parameters influences of semi-fixed abrasive plate on the ‘trap’ effect with discrete element simulation by Particle Flow Code (PFC). The effects of the property parameters such as porosity, hardness and size of the abrasive particles, friction coefficient between the abrasive particles and the bonding agent concentration are simulated. The simulation results show that porosity, friction coefficient, bonding agent concentration has great influences on the ‘trap’ effect, while hardness and size of the abrasive particles almost have no effect. Grey incidence analysis is carried to determine the influence degree of porosity, friction coefficient, bonding agent concentration, and the results show that the most important factor is the porosity, followed by the friction coefficient, and then the bonding agent concentration.
Authors: Shi Ming Ji, Li Zhang, Ming Sheng Jin, Qiao Ling Yuan, Ya Qi Shen
Abstract: Polishing is an important technics processing in order to obtain the high quality surface of mould in industry mould manufacture. For the moment, polishing of the free-form curved surfaces of mould is performed by manpower. So it is important to research gasbag polishing technology. This paper has been developed dynamic numerical simulation for gasbag polishing process based on the new type of polishing tools by FEM. On the material removal theory, influence of the shape of the structure of the gasbag, angular velocity and the air pressure inside the air gasbag on the campaign polishing process are explored. It can be used to provide technology support to establish polishing process database.
Authors: Cai Xu Yue, Xian Li Liu, Dong Kai Jia, Shu Yi Ji, Yuan Sheng Zhai
Abstract: A 3D model is established in this paper to simulate cutting process of PCBN tool cylindrical cutting hardened steel GCr15 using ABAQUS/Explicit. The model effectively overcomes serious element distortions and cell singularity in high strain domain caused by material large deformation by adopting shear failure criteria and element deletion criteria. In this study cutting force, cutting temperature, surface residual stress field as well as side flow are forecasted of hard cutting process with chamfering tool preparation. It shows that satisfactory results could be obtained by FEM. The simulation results provide theoretical basis for studying hard cutting mechanism and selecting the best cutting condition in practical.
Authors: Yu Ping Ma, Ming Chen, Fang Hong Sun
Abstract: Diamond films was deposited on cemented carbide tools with two-step pretreatment method under different distances between the substrates and hot filaments, and the effect of the distance between the substrates and hot filaments on the crystallographic orientation of diamond films and the characteristics of diamond coated tools was investigated in bias-enhanced HFCVD system in this paper. The cutting performance of diamond coated tools was verified by the experiments of cutting particles reinforced aluminum base composite material with 15 vol.% Si as compared with uncoated ones. The quality of diamond film was analyzed by means of Scanning Electron Microscopy(SEM), Raman spectroscopy, and X-ray diffraction. The optimization deposition processing was obtained. The relative intensity ratio of (111) facet and (220) facet in the film tested by XRD was one third. The cutting performance of diamond coated tool was improved significantly when machining the Si particle reinforced aluminum-based metal matrix composite; its lifetime was 30 times longer than that of uncoated one. The work done in this paper was of great practical significance to accelerate the industrialization of diamond films coated WC–Co substrates.
Authors: Dong Hui Wen, Xian Li Liu, Tao Hong
Abstract: The formation mechanisms and properties of white layers produced in precision hard part machining of GCr15 hardened steels are not clearly understood to date. Microstructure of white layers formed during machining of GCr15 hardened steel (62±2 HRC) was investigated. Hard turned surface with white layer usually consists of three layers: a white layer (untempered martensite), a transition layer (over-tempered martensite), and the bulk material. Martensite, austenite and carbide are observed in the white layer, hardness of white layer is larger than that of bulk material and transition layer, it was caused by extremely small grain size and high dislocation density. The depth of white layer is about 7-14µm with the flank wear reached 0.1mm, the optimal width of the flank wear which generated low depth of white layer is essential to perform the super-finishing process.
Authors: Wei Peng, F.Q. Liu, C.Y. Yao
Abstract: The interfacial bonding strength between ultraviolet-curing resin and diamond is a key factor affecting tool properties in manufacturing of ultraviolet-curing wire saw. Therefore, in this paper, the application of surface-modified diamond coated metal was studied in ultraviolet-curing wire saw aim at retention problem of diamond in bond. Effects of surface-modified diamond were evaluated according to model of tensile test. Furthermore, retention mechanism of diamond was analyzed according to bond theory. The experimental results prove that the machining properties and service life of ultraviolet-curing wire saw can be improved by surface modification of diamond.
Authors: Yang Wang, Li Jun Yang, J. Tang, L. Li, Yan Bin Chen
Abstract: The processing effect using water-jet guided laser micromachining technology is determined by the accurate coupling of focused laser and high speed water-jet. In order to realize the effective coupling, based on the analysis and calculation, a coupling unit with special structures was designed. The maximum angle of incidence was researched, which determined whether the total reflection occurred when laser transported in the water-jet. By the aid of fluid dynamical simulation, the coupling unit with uniform distribution of inner-cavity fluid field was designed. The attenuation of laser energy in water-jet fiber was investigated. Using appropriate laser wavelength, pulse energy and filtered and de-ionized water, energy attenuation in fiber was reduced. Experimental results showed that applying this coupling technology, perfect water-jet guided laser micromachining can be achieved.
Authors: Yan Wei Zhao, J.F. Du, Si Wei Wen, Yuan Kun Gui
Abstract: Based on virtual prototyping technology, dynamic simulation of PE-1 type ultra-precision double-sided polishing machine and its technologic parameter optimization was studied. Through the simulation of virtual prototype, which was built in ADAMS, the polishing process was analyzed. Firstly, the simulation of polishing process shows that the ratio of rotation and revolution angular speed is inversely proportional to input speed ratio of planetary system. Secondly, the simulation of movement route shows that points along the same radius have similar route style considering the same input speed ratio of planetary system. Thirdly, the optimization of material removal non-uniformity shows that the higher speed makes for higher removal quality, the speed of solar gear and gear ring is opposite when the optimum value reached. At last, the maximum removal rate was achieved on the condition of same press and speed of plate, and corresponding solar gear speed and gear ring speed were gained.

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