Papers by Author: He Wang

Abstract: Grinding is a main method of silicon nitride ceramic in finish machining stage. The technical parameters had an important influence on the surface quality of silicon nitride ceramic. The silicon nitride ceramic spindle was ground by the high-speed cylindrical grinder MGKS1432-H. The relations between different speed parameters and surface roughness were researched. The cylindrical and internal high speed grinding experiments of silicon nitride ceramics spindle were carried out. The S-4800 scanning electron microscope was used to explore the roughness change rule of the grinded surface under the condition of only changed grinding wheel’s velocity. In the process of cylindrical and internal grinding on silicon nitride ceramic spindle, the roughness tended to decrease with the linear velocity increasing, and increased with the radial feed speed increasing and decreased with the wheel shaft’s oscillation speed increasing. The result indicated that the linear velocity of grinding wheel influenced the sample’s roughness most. The effect of radial feed speed on the roughness is next only to the effect from linear velocity. The effect of shaft’s oscillation speed on the roughness is the lowest of the three factors. In the process of internal grinding, with the linear velocity increasing, the ceramic material transformed from brittle rupture to plastic deformation and the roughness appeared one peak. These results were very helpful to optimize the grinding parameters and improve grinding efficiency.

Abstract: Diamond films and diamond/graphite composite films have excellent wear resistance, it can be used as the protective coating to effectively improve the parts life and performance. The micro crystalline diamond films, nanocrystalline diamond films and diamond/graphite composite films were prepared on sic substrate by microwave plasma chemical vapor deposition on different power, pressure and CH4 concentration growth parameters. The films surface characteristics were research by SEM and Raman spectrometer. The results indicate that the diamond grain size and content decreased and graphite content increased with CH4 concentration increasing on constant microwave power and cavity pressure; the diamond grain size decreased and graphite constant increased with cavity pressure increasing on constant microwave power and CH4 concentration.

Abstract: The zirconia parts are limited by machined surface quality. The grinding force is one of the most important parameters of grinding and has effects on surface quality. The MK2710 grinder and resin bond diamond wheels were used in zirconia grinding. The grinding force was obtained by Kistler dynamometer. The paper focused on wheel speed and grain size on grinding force, and examined the surface by SEM. The research results indicated that decreasing the grain size, the grinding force increased and the surface quality improved, and increasing wheel speed could decrease grinding force to improve grinding surface quality. The results can improve zirconia ceramic parts surface quality and promote application.

Abstract: Tunnel Boring Machine (TBM) is a major equipment used in underground engineering and Cutter disk system is its major parts, which affect sharply its capability. The force and vibration characteristics of the cutter system are simulated in this paper, and the effects of its force and vibration on the cutter system reliability are analyzed. These results show that there are the most stress and the worst reliability in these joints between the cutterhead and main driver, the cutterhead and the hob, and cutter ring. These research results are very helpful for increasing the reliability and application of the rock boring machine.

Abstract: Disc cutter is the key part in Tunnel Boring Machine (TBM). Wear and tear of disc cutter is the main reason of low efficiency and high cost of this machine. Forces and deformations of disc cutter ring are foundation for its design and assembly. In this paper, the analysis of stress and deformation are carried to study their distribution; Wear mechanism of disc cutter ring is presented; modal analysis is carried to study the vibration of disc cutter ring. The results show the yield strength and rigidity of disc cutter ring is very high; disc cutter ring can avoid resonance and meet the engineering requirement. The results are very helpful for digital design of disc cutter ring used in different geology conditions.

Abstract: This paper reports on the wheel wear in high speed grinding silicon nitride used metal bond diamond wheels. The investigation focuses on the relation among grinding force, grinding ratio and wheel wear. Experiments have been performed to investigate the factor of wheel wear such as grinding ratio and grinding force. The results of these investigations are presented in this paper. With the application of this technology, a low cost production and high efficiency of ceramic bearing ring grinding can be realized.

Abstract: In ceramic machining field, the ultimate goal is to keep material surface integrity, dimension precision and max material removal rate synchronously. HIPSN ceramic ring high speed grinding experiments and researches have been performed, by testing and analyzing grinding force, combining grinding motorized spindle dynamic performance with grinding surface roughness, the influences on ceramic machining quality have been discussed. The grinding parameter can be chose in precondition promising machining quality. It possesses guidance significance in low cost, high efficiency precise ceramic parts machining.