Advanced Materials Research Vols. 69-70

Abstract: Grinding fluid has an important effect in processing work piece, so in view of the new grinding fluid, a large number of tests have been taken in the application of the power ultrasonic vibration honing. The massive experimental study, separated from the work piece’s surface roughness, the work piece’s surface rubbed deterioration layer and the influence to the processing characteristic with different density of the new grinding fluid and so on, discussed the adaptability of the new grinding fluid in power ultrasonic vibration honing processing. The research has been indicated that although the new grinding fluid does not surpass the traditional working fluid, such as emulsion and liquor, in cooling performance, it has a better lubricating property and has the obvious superiority in the working accuracy and the oilstone’s length of life. Therefore the new self-developed grinding fluid is suitable for the power ultrasonic honing processing.

Abstract: In this paper, the comparative experimental research on DPSS UV laser (wavelength is 355nm) and high-pressure water-assisted YAG laser dicing SiC wafer was done. The results show that is strict with the performance of laser source and the dicing technique parameters in UV laser dicing the SiC wafer, and the dicing surface of good quality can be obtained only when the parameters of laser source and dicing technology vary in a narrow range. Contrarily, the SiC wafer dicing technology using high-pressure water-assisted YAG laser has a perfect flexibility with the laser source and dicing apparatus, and the good dicing surface can be obtained even if the process parameters vary in a wide range.

Abstract: Cathode design is a difficult problem must be faced and solved in ECM. We develop a new numerical approach for cathode design by employing a finite element method and this approach has been applied in the cathode design of aero-engine blades in ECM. The mathematic models of the electric filed and electrolyte flow filed distribution in EMC process are described primarily. Then the realization procedure of this approach is presented，in which the effects of electric filed and electrolyte flow filed distribution within the inter-electrode gap domain are concentrated. In order to verify the machining accuracy of the designed cathodes, the experiments are conducted using an industrial scale electrochemical machining system. The experimental results demonstrate that the machined blade have high surface quality and dimensional accuracy which proves the proposed approach for cathode design of aero-engine blades in ECM is applicable and valuable.

Abstract: Semi-fixed abrasive is a novel abrasive. It has a ‘trap’ effect on the hard large grains that can prevent defect effectively on the surface of the workpiece which is caused by large grains. In this paper, some relevant experiments towards silicon wafers are carried out under the different processing parameters on the semi-fixed abrasive plates, and 180# SiC is used as large grains. The processed workpieces’ surface roughness Rv are measured. The experimental results show that the surface quality of wafer will be worse because of higher load and faster rotating velocity. And it can make a conclusion that the higher proportion of bond of the plate, the weaker of the ‘trap’ effect it has. Furthermore the wet environment is better than dry for the wafer surface in machining. The practice shows that the ‘trap’ effect is failure when the workpiece is machined by abrasive plate which is 4.5wt% proportion of bond in dry lapping.

Abstract: Electrical and magnetic characteristics of motorized spindles have a great effect on machining quality of ultra-precision machine tools. Bad characteristics will result in significant heat losses, low efficiency and large vibration. Study on optimizing electrical and magnetic characteristics of an inverter-fed induction motor is presented in this paper. A method of optimization design of an inverter-fed induction motor is given. The method is used to design a motor used for an ultra-precision machine tool motorized spindle. By comparing the optimal design with the traditional one, it shows that the total electrical and magnetic heat losses are obviously decreased and the efficiency can be improved.

Abstract: Series of simulation of planetary precise ball lapping modes are put forward in this article, which use solid abrasives to get a high lapping efficiency. In this case, it is very important to obtain a better quality especially a better uniformity. Based on the simulation. of this new lapping mode, it is found that the lapping trace are mainly influenced by the eccentric distance and other factors.

Abstract: Water-lubricated hybrid journal bearings have been developed to support the ultra-precision machine tool spindles, due to the prominent properties of high load capacity and stiffness, high rotational accuracy, excellent thermal stability, low power consuming and environmental friendliness. Quasi-analytical procedures are deduced to present a relatively easy and rapid method for estimating of the parameters of the water-lubricated hybrid bearings without resorting to complex full numerical calculation. The procedures are based on the lumped resistance method, which have been extended to the situation dominated by the turbulence and inertia effects. The results show good agreement with the full numerical solution, especially when the bearing operating at moderate eccentricities. The procedures can be taken as a real time analytical tool for parametric study and preliminary engineering design of water-lubricated hybrid journal bearings.

Abstract: In this paper, the batch processing of Φ35mm WC-Co cemented carbide balls used in one-way value is studied by rotated dual-plates (RDP) lapping machine. On the basis of this innovated equipment, the processing parameters, including abrasive grain, rotating velocity and load, are changed legitimately in experiment. The experimental results show that the abrasive grain is used from big to small, while the rotating velocity and load are gradually reduced in order to improve the uniformity of lapping trace distribution on the ball surface in batch processing. Finally the rational course and parameters are defined, these WC-Co cemented carbide balls satisfy the products’ final demand which means the sphericity error (Rnd) is less than 1μm and the roughness of surface (Ra) is better than 50nm. Because of the feasibility, the precision of final WC-Co cemented carbide balls improves and can be applied in one-way value used in oil exactor.

Abstract: Aluminum nitride (AlN) ceramic has excellent electrical insulation and dielectric properties. The ultra-precision lapping and polishing techniques for the AlN substrate are studied in this paper, and the influence of the lapping parameters such as load and slurry on the surface roughness, material removal rate of AlN is discussed. The surface of workpiece after processing is observed with microscope to analyze the material removal mechanism. An extremely smooth surface with roughness 6nm Ra is obtained after the finishing process. It is also found that the gap between grains will decrease the precision and quality of AlN substrate.

Abstract: To study the lapping process and sphere-shaping mechanism of WC-Co cemented carbide ball under eccentric dual-rotating (EDR) V-groove lapping mode, the research center designs EDR V-groove lapping machine. This paper analyses sphericity of WC-Co cemented carbide balls after the lapping. During the lapping process, the diameter variation is measured every one hour. The diameter of ball is usually reduced 0.05mm every hour, which is more than the dual rotating plates(DRP) lapping mode, and the experiment is totally done 9 hours, the error of sphericity can be controlled around 0.005mm in the last, so the EDR V-groove lapping mode is more suitable for lapping of the WC-Co cemented carbide ball in roughness and semi-finishing process. In order to compare the material removal rate between DRP lapping mode and EDR V-groove lapping mode, the balls are also lapped under DRP lapping mode.