Papers by Author: Shu Sheng Li

Abstract: This paper studies the grinding temperature field of non-quenched and tempered steels grind-hardening technology using experiments and finite simulation. A mathematical model of grind-hardening temperature field is established to investigate steel 48MnV which is used for making crankshaft. The grinding temperature field is simulated and the hardened depth is forecasted by finite-element method with the triangular shape of the heat source model based on the ANSYS software. The experimental results show that the simulative temperature and estimating hardened depth are comparatively close to the measuring ones. The model could be utilized to forecast the distribution and variation characteristics of the grinding temperature field and the hardened layer depth.

Abstract: A new segmented grinding wheel of the brazed monolayer diamond was developed with a defined grains pattern on the wheel surface. Results of grinding zirconia using brazed segmented diamond wheel were presented. The experiment results showed that the grinding forces ratio becomes higher with the increasing of the specific material removal rate and the specific energy falls with the increasing of the maximum undeformed chip thickness during grinding zirconia process. In this investigation, brazed diamond wheels with defined distribution patterns was conditioned by touch-dressing method so that grit tips get micro-conditioned and allow the underlying grits to participate and consequently improve the quality of finish. All the ground surfaces of zirconia were generated by the combined removal modes of brittle and ductile.

Abstract: The temperature, time and cooling rate are key factors in the hardening process using the grinding heat instead of the high frequency induction heat source. Thus, this paper established the mathematical model estimating the grind-hardening temperature, experimentally determined the grinding temperature and the cooling rate of different grinding parameters for 48MnV microalloyed steel using the conventional aluminum grinding wheel on a surface grinder, and investigated the grind-hardening effects and the forming mechanism of grind-hardening layer. The results show that the estimating temperatures are comparatively close to the measuring ones and hence the model could be utilized to optimize the processing parameters, and the satisfactory grind-hardening temperature and cooling rate could be achieved under the optimized processing parameters. The microstructure of the grind-hardening layer, the fine needlelike martensite in the entirely hardened zone, the martensite and ferrite in the transitional region is similar to that acquired through the high frequency induction technique. Especially, the average hardness of the entirely hardened zone is 740HV and the depth of the hardened layer is adjacent to 1.5mm, which indicate that the grind-hardening effects are very excellent. Different from the forming mechanism of the high frequency induction hardened layer, higher grind-hardening temperature is needed to compensate shorter time austenitization, and because of thermo-mechanical loading induced during grinding, from surface to inside, the morphology of martensite changes from fine to thicker, then to finer, other than from thick to finer.

Abstract: A kind of brazed monolayer diamond grinding wheel was developed with a relatively regular distribution of grains on the wheel surface. Grinding performances of this kind of brazed wheel in the surface grinding of cemented carbide were studied. The experiment results show that the grinding forces ratio becomes higher with the increasing of the maximum undeformed chip thickness and the specific energy falls with the material removal rate during grinding cemented carbide process. Under certain grinding conditions, the material was removed almost through plastic deformation and good surface quality is gained. Furthermore, the grits of the brazed diamond grinding wheel fail mainly in attritious wear modes other than pull-out ones in conventional electroplated and sintered diamond tools, which indicates that the strong retention of brazing alloy to the diamond grits and longer service life of this kind of wheel.