Papers by Author: Lan Yan

Abstract: Grain-workpiece interface, which resembles a micro-cutting process, directly modifies the workpiece surface and dominates all the output measures of a grinding process. The abrasive grains always become worn or dulled during grinding, which alters the grain-workpiece interface output and turns to be the primary factor that causes the transient or time dependent behavior in monolayer superabrasive grinding. Therefore, the study on how the grain wear influences the grain-workpiece interaction through micro-cutting analysis becomes necessary. As the emergence of the packaged FEM software for micro-cutting simulation, apart from single grit cutting test, it enables another qualitative and quantitative investigation method on grain-workpiece interface mechanism in an efficiency and effective manner. Based on previous efficacy verification of Third Wave AdvantEdge^TM, the FEM simulation is carried out to investigate the effect of grain wear on its micro-cutting performance. The simulation results provide an illustrative manner to interpret the phenomenon and mechanism, and the results can be used in the grinding process modeling in the future as well.

Abstract: White light interferometer was employed to measure the surface topography of 60# and 120# alumina grinding wheel. The correlation of wheel topography and its performance was characterized through the three-dimensional (3D) surface characterization parameters of “Birmingham set”. Birmingham parameters were used to characterize the performances of grinding wheel, in items of grain density, grain shape and grain sharpness. The effects of sampling interval on the 3D surface parameters were analyzed and the optimal sampling interval was selected to calculate the 3D surface parameters.

Abstract: For the analysis of cooling effect, the cutting inserts were heated to 900°C and then exposed in the room-air and cold-air with different pressure respectively. The temperature variation were recorded by infra-red (IR) pyrometer. The temperature-dependent global heat transfer coefficients were estimated by the theoretical analysis and experimental data. The finite element analysis (FEA) was employed to simulate the cooling process and modify the estimated heat transfer coefficients. The heat transfer coefficients decreased from 55.1 W/m2•°C (800°C) to 9.32 W/m2•°C (350°C) in the natural cooling and approximately 300 W/m2•°C (600°C) to 60 W/m2•°C (300°C) in the cold-air cooling. Cold-air cooling greatly increased the heat transfer coefficients, but it seemed the air pressure had little pressure on the heat transfer coefficients.

Abstract: Grinding process can be considered as micro-cutting processes with the irregular abrasive grains on the surface of grinding wheel. The grain-workpiece interface directly forms the workpiece surface. Therefore, the study of the grain-workpiece interaction through micro-cutting analysis becomes necessary. But the experiments for single grain cutting are difficult to perform. Aimed at this problem, single grain cutting simulations of AISI D2 steel with a wide range of cutting parameters have been carried out with AdvantEdgeTM in this study. The effect of cutting parameters on cutting force, specific cutting force, material removal rate and critical depth of cut has been analyzed.

Abstract: In this study, orthogonal arrays were applied in the design of the experiments and Ti6Al4V end-milling experiments were performed on the DAEWOO machining center. The white light interferometer was used to obtain the average surface roughness (Ra). A quadratic model was proposed to fit the experimental data of the surface roughness. And the fit model was used to optimize the cutting parameters in the given material removal rate. Finally the verification experiments showed good agreement with the estimated results.

Abstract: The grinding process can be considered as micro-cutting processes with irregular abrasive grains on the surface of grinding wheel. Single grain cutting simulation of AISI D2 steel with a wide range of cutting parameters is carried out with AdvantEdgeTM. The effect of cutting parameters on cutting force, chip formation, material removal rate, and derived parameters such as the specific cutting force, critical depth of cut and shear angle is analyzed. The formation of chip, side burr and side flow is observed in the cutting zone. Material removal rate increases with the increase of depth of cut and cutting speed. Specific cutting force decreases with the increase of depth of cut resulting in size effect. The shear angle increases as the depth of cut and cutting speed increase. This factorial analysis of single grain cutting is adopted to facilitate the calculation of force consumption for each single abrasive grain in the grinding zone.