Papers by Author: Feng Liu

Abstract: In this paper, friction behavior of textured carbide and steel surface has been studied in order to investigate the effect of different patterns. Several simple textures have been fabricated using straight groove grinding wheel. By microstructuring, various spacing and height of the structure, we investigate the role of topography in terms of friction characteristic. The change of friction behavior has been tailored by grinding operation using straight grooved wheel and evaluated in terms of friction. Friction values were measured by Tribometer. Frictional properties of textured carbide and steel surfaces were assessed with the help of parallel steel slider with 2000g normal force under dry condition using four different sliding speeds. It is found from the experiment that except 30° and 90° angle patterns, rest of the patterns on carbide surfaces show friction reduction which is roughly from 0.15 to 0.13. On the other hand, similar textured patterns can reduce the COF from 0.17 to 0.13 in case of steel surface.

Abstract: With the correlation in stochastic process applied to the experimental results, the surface during grinding and further lapping with abrasive jet finishing (AJF) restricted by grinding wheel was investigated with respect to auto correlation function (ACF) , cross correlation function (CCF) and power spectral density (PSD) analysis. The results indicated that AJF made the surface contour formed periodicity in a small range and removed fluctuation of the surface contour in low frequency greatly. The average spacing of the surface contour decreased and the machined surfaces changed from continuous parallel micro-groove and plough to randomly distributed discontinuous micro-pit with the increase of machining circles. The surface texture became fine and surface roughness was obviously improved. Furthermore, the isotropy surface and uniformity veins both parallel and perpendicular machining direction was attained by the finishing process to improve greatly the wearable capability of the workpiece.

Abstract: Abrasive jet finishing process is a novel process whose objective is to remove surface defect layer and to diminish roughness and ripple after grinding. Experiments were performed with plane grinderM7120 and workpiece material 45# steel which was ground with the surface roughness values of Ra =0.2-0.6 μm . The machined surface morphology was studied using SEM and the microcosmic geometry parameters were measured with MICROMESVRE2 instrument. In this paper, with the fractal dimension, Ra , Rq and the supporting rate curve, the surfaces of grinding machining and abrasive jet finishing machining were researched. The result indicated that the machined surfaces changed from continuous parallel micro-groove and plough to randomly distributed discontinuous micro-pit could be observed with the increase of machining circles and surface roughness was obviously improved. Furthermore, the isotropy surface and uniformity veins both parallel and perpendicular machining direction were attained by abrasive jet precision finishing with grinding wheel as restraint. The supporting rate curve of the surface profile can be increased. This is favorable for the wearable capability of the workpiece.

Abstract: Surface microcosmic topography finished by abrasive jet with grinding wheel as restraint was analyzed and evaluated. Generating mechanism of surface morphology finished by abrasive jet with grinding wheel as restraint was investigated and surface topographical characteristics were also evaluated with cross correlation of random process. Experiments were performed with plane grinder M7120 and workpiece material 45# steel which was ground with the surface roughness values of Ra=0.2
0.6m. The machined surface morphology was studied using SEM and microscope and the microcosmic geometry parameters were measured with TALYSURF5 instrument. The experimental results shown that the machined surface change from continuous and parallel micro-groove and plough to randomly discontinuous micro-pit can be observed with machining circles increasing and surface roughness was obviously improved. Furthermore, The finished surface has little comparability compared to grinding machining surface.The isotropy surface and uniformity veins both parallel and perpendicular machining direction were attained by abrasive jet precision finishing with grinding wheel as restraint.