Papers by Keyword: Force Ratio

Abstract: In the present research work, a new precision sawing technique is proposed, by which the ceramic workpiece is ultrasonically vibrated along the blade radial direction during the sawing operation using a diamond blade. In this study, experiments are conducted to study the sawing force characters of ultrasonic vibration-assisted sawing (UVAS) and conventional sawing (CS). The influences of the sawing parameters on the sawing force and force ratio are investigated. The results show that the sawing force in UVAS is smaller than those in CS. It was found that applying ultrasonic vibration to the sawing operation decreased the normal sawing force 18%-38% and tangential sawing force by 10%-25%. The force ratio in UVAS is lower than that in CS, which reveals that diamonds are easier to cut into the ceramic workpiece and the material machinability is improved.

Abstract: Grinding forces characteristics in elliptical ultrasonic assisted grinding (EUAG) of sapphire are investigated experimentally. The EUAG is a new grinding method proposed by the present authors in which an elliptical ultrasonic vibration is imposed on the workpiece by using an elliptical ultrasonic vibrator. In this paper, grinding experiments under the presence/absence of ultrasonic vibration assistance are performed. The effects of the vibration amplitude and grinding parameters such as the depth of cut, the grinding wheel speed on the grinding forces, grinding force ratio F_n/F_t are clarified. The obtained conclusions are as follows: the grinding forces during EUAG lowers to 50% and grinding forces ratio becomes reduced by 33% compared that during conventional grinding (CG); the grinding forces during EUAG have the less variation rate than those during CG as grinding parameters change; higher grinding wheel speed causes the larger grinding forces in CG, but has little effect on the variation of grinding forces in EUAG. By using EUAG method, the grinding forces and force ratio are greatly decreased, and surface quality is better, meaning that grindability of sapphire material is improved.

Abstract: The relationship of the friction coefficient and the MTC were discussed, and the MTC and its effects on surface roughness were a theoretical analysised and experimental verification by AFM (atomic force microscope). The results show that the theoretical MTC tends to be minimal value then before the adhering effect to reach remarkable. Appropriate adjustments cutting parameters, the cutting process can always micro-cutting phase to reach the steady-thin chip, and no plowing phenomenon. So the surface residues highly were reduced and higher surface quality was achieved.

Abstract: Nanoscratch tests showing clear ploughing behavior and stable chip formation was conducted to investigate the influence of friction coefficient on the minimum thickness of cut. A theoretical model accounting for the minimum thickness of cut is used to analyze the effects of the friction coefficient and force ratio. Results show that the minimum thickness of cut is strongly dependent on both friction coefficient and force ratio. Theoretical minimum thickness of cut can be obtained when adhesion friction plays a dominant role in the cutting process. Appropriate adjustments of processing parameters are hereby suggested to result in stable micro-machining process without ploughing, not only forming fine-thin continuous chip, but also achieving high surface quality. The role of friction coefficient on the minimum thickness of cut with δ (cutting depth/edge radius) is also discussed.