Papers by Author: Dun Wen Zuo

Abstract: The crater diameter and depth of the surface machined by electrical discharge machining (EDM) were used to evaluate indexes for EDMed surface. The influence of discharge parameters selected on the crater diameter and depth in mirror-like surface EDM process was investigated, and the optimization scheme was obtained. An L16 (44×23) Taguchi standard orthogonal array was chosen for the design of experiments. Experimental results indicate that peak current and open discharge voltage have more influence on the crater diameter and depth in comparison with pulse off-time and pulse duration. Also the results confirm that the crater depth is about 10 to 20 percent of its diameter while the near-mirror EDM conducted in the NAK80 steel with fine discharge parameters.

Abstract: Based on the vacuum plate glazing produced in laboratory, the residual stress field of seal edge in vacuum plate glazing caused by heat load was researched by electrometric method, and the distribution of residual stress field were successfully measured. The residual stress field of seal edge in vacuum plate glazing was analyzed by numerical calculation, and then the established mathematical model was solved by finite element method and distribution rule of its residual stress was obtained. The effect of linear expansibility and coupled stress of the solder in seal edge on the residual stress of vacuum plate glazing was discussed. The result showed that calculated and experimental results were similar. The relation between intensity of residual stress and elasticity modulus was obtained. The theoretical principle was provided for analyzing allowable value of the residual stress of seal edge in vacuum plate glazing.

Abstract: The cutting force in manufacture process was observed with Kistler dynamometer. A special clamp was designed to simulate the real condition of blade cutting. Series of experiments were done. Cutting force reflected structure of the blade and movement of machine. Cutting force was changed with feed speed varied and the rotation of axis B & C. Resultant cutting force was uniform in back and basin of blade and increased with cutting speed went up. Resultant force was waved in edge of blade. Back and basin forces were lager than edge force in X direction. Force X invoked vibration.

Abstract: Boron-doped micro-nanocrystalline diamond coating may be successfully prepared on Mo substrate with DC arc plasmas jet deposition device. Along with the increase of doped-boron concentration in the film, two-point resistance measurement indicates that film resistance presents exponential decrease; Raman spectrum test shows that, the characteristic peak value of diamond 1332cm-1 in the spectrum moves toward low frequency, the semi-height width of diamond peak, peak D and peak G, etc. in the spectrum is expanded, and the component of non-diamond bonds such as sp2, etc. in the film is increased; SEM and AFM observation shows that, increasing the doped-boron concentration could further subdivide the crystal grains in the film, and is beneficial for the growth of nano- or ultra-nano-crystalline diamond film; film annealing test shows that, micro-nanocrystalline diamond film with higher doped-boron concentration has better thermal stability than the micro-nanocrystalline diamond film without doped boron.

Abstract: Chemical vapor deposited (CVD) diamond film has a series of outstanding properties. However, it can not be easily machined by conventional technologies available currently for its high hardness and stability. Laser processing diamond film method can be an efficient way to process diamond film because of its high energy density. The mechanisms of laser processing diamond film are thermal oxidation, graphitization and evaporative ablation of graphite. Temperature distribution is of great importance to understand these complex phenomena taking place during the process because different temperatures lead to different physical and chemical changes of diamond. In this paper, the finite element method (FEM) software ANSYS is applied to calculate the temperature distribution. The relation between etching depth and laser machining parameters (laser power and scanning speed) is presented. The proper parameter ranges of laser power and scanning speed for a certain etching depth is also investigated with this method.

Abstract: The exchange of the heat of the IFA polishing system was analyzed at first in this paper. Then the three-dimensional temperature finite element model was set up. By changing the material of the elements, the ice-melting process was simulated. It was found that the obtained simulating results showed a good agreement with the experimental results. The temperature distribution and the melting rate were studied in the case of different technical parameters, which can be used to provide references for choosing better parameters.

Abstract: It is very difficult to predict the CNC milling process of monolithic components in aero-industry by either theoretical analysis or experimental research，because of their complicated structure. The machining distortion becomes one of the neck problems in the rapid development and the efficient production of our national defense weapons. The milling process of monolithic components web is simulated by 3D FEM， and the residual stress distribution and the variation tendency of the milling distortion are obtained， comparing the simulation results and the real measurement in the distortion，the proposed model is proved to be effective.

Abstract: The research was carried out on the parameter optimization of milling titanium alloy in this paper. The cutting models including cutting force, tool life and machined surface roughness are obtained by orthogonal array experiments. The maximum metal removal rate, MRR is selected as objective function. The constraints related to machine tool, workpiece, cutting tool and other machining situations are presented in details. Genetic algorithm is used to search for the optimum milling parameters for the maximum metal removal rate of titanium alloy. The optimization results show the optimization system can improve the productivity of milling Ti6Al4V obviously.

Abstract: The abrasive ice disc chemical mechanical polishing (AID-CMP) is a potential polishing process in the semiconductor industry to realize superior surface finish and planarity for semiconductor wafers. In this paper we investigated the temperature field during GaAs wafer AID-CMP process for a better understanding of AID-CMP. The results show that the AID outer temperature is higher than the inner, and the highest temperature in AID is at the wafer/AID contact zone. The increases of Pc, v, eh and tp will generate more energy and cause more local melting during GaAs wafer AID-CMP process. The AID temperature and the area of highest temperature zone increase with increasing Pc, v, and eh. The nodes temperature increase in every conditions adopted as tp increases. The area of melted zone and thickness of melted ice increase with increasing Pc, v, eh and tp.

Abstract: The mathematic model was established between finished surface residual stress and milling parameters by orthogonal regression testing. The rationality of the model was certified by FEM and test. The simulation hypothesis and process were verified by the model. The test showed that the model and FEM were feasible.