Papers by Author: C.S. Liu

Abstract: This paper worked on two dimensional ultrasonic grinding system with workpiece adhered to ultrasonic vibration. It analyzed the working locus of abrasive particle under two dimensional ultrasonic grinding (TDUG), and emulated the working course, and gave the key parameters affecting grinding efficiency and grinding locus’s characteristic under different grinding parameters, and brought forward the cutting course between abrasive particle and workpiece under TDUG belongs to an new rotating dynamic contact cutting model. At the same time, it put forward the theoretically critical speed condition under TDUG to obtain the optimum grinding effect, and verified good micro-feature of finished surface under TDUG by the means of grinding tests of nano ZrO2 ceramics.

Abstract: Experimental researches on material removal rate and surface roughness of Al2O3 engineering ceramic guide-pulley lapping were carried out using W20 and W5 fixed oilstones by self-developed ultrasonic lapping tool both with and without ultrasonic assistance. Experimental results show that lapping speed, lapping pressure and grain size produce different effects on the lapped surface roughness and material removal rate. The material removal rate in ultrasonic lapping process is two times as large as that in traditional lapping, and the ground surface roughness is superior to that in common machining method. The material removal rate increases along with the average diameter of grains and the lapping speed both in ultrasonic lapping and traditional lapping. In traditional lapping process the material removal rate becomes bigger along with the lapping force, while in ultrasonic lapping it gets the optimal value with the lapping force 450N. The value of lapped surface roughness increases along with the lapping speed in traditional lapping, on the contrary it decreases contrast to the lapping speed until 250rpm in the ultrasonic lapping. The value of traditionally lapped surface roughness decreases contrast to the lapping force, whereas it achieves the minimum with the lapping force 450N with ultrasonic assistance.

Abstract: On the basis of analyzing the brittleness, ductileity, and the removal mechanisms of the^nano-ZrO2 Ceramics, the critical ductile grinding depth formula of the nano-ceramics was established. Due to superductileity of the nano-ZrO2 ceramics, it couldn’t apply the formula of the common engineering ceramic material according to experimental results. The value of material coefficient ζ has relations with not only the material characteristics but also the processing methods and the processing parameters. It was proved that ζ has great effects on the accuracy of theoretical calculation. Experimental results showed that the critical ductility grinding depth of the nano-ZrO2 ceramics is up to 12 µm in common grinding methods, while in ultrasonic grinding is up to 20µm. The grinding chips with and without ultrasonic vibration assistance were discussed.

Abstract: Metal matrix composites（MMCs）is applied widely in recent years because of its excellent performances, but the machining is very difficult due to the rigidity of reinforced-phase in it, so, the application of MMCs is restricted much. In this paper the experiment of common and ultrasonic vibration drilling is performed to SiC particulate reinforced Al matrix composites （SiCp/Al）by use of carbide-alloy-twist-drill, and the surface roughness of hole is compared, furthermore, the wearing of twist drill and the feature of chips are analyzed by scanning electron microscope (SEM). From above, we can draw aconclusion that ultrasonic vibration drilling may meliorate the mechanism of drilling to some extent and it takes on much superiority that the common drilling is unmatched, so this method could provide a certain foundation for the posterior study and application.

Abstract: Nano ceramics possessed ascendant mechanical property and physical characteristics contrast with engineering ceramics, so it has extensive application prospect in various industries. On the basis of applying the indentation fracture mechanics to analyze the removal mechanics of ceramic material, this paper analyzed the critical ductile grinding depth of the nano ZrO2 ceramics. Adopting ultrasonic composite processing we describe the influence of different processing parameters and grain size of diamond wheel on the grinding forces and surface roughness. Based on the grinding forces and surface roughness the grinding process with and without vibration is analyzed. By means of SEM and AFM the surface character and critical ductile grinding depth of nano ZrO2 ceramics are also discussed. The paper supplied the theoretical and experimental basis for the grinding of the large-sized ultraprecision plate structure of nano ZrO2 ceramics (nm).