Papers by Keyword: Single Grain

Abstract: The grain orientation plays a great important role during single grain grinding. Single grain grinding simulation could offer an insight into the material removal behavior. However, grinding simulation with FE methods has problems arising from large deformations at the chip root and negative rake angles of the grain. In this work, a coupled Eulerian-Lagrangian method (CEL) is used to model the grinding behavior of single diamond grain in different orientations. The influence of the grain orientations on the grinding forces, grinding process (sliding, ploughing and cutting) and critical undeformed chip thickness are analyzed. The force ratio shows great accordance with the analytical calculation data. The simulation results show that the chip generates quickly and the special grinding force is relatively small when the diamond particle is in octahedral orientation (111)-(100). The workpiece material flows to the side and front owing to the pressing of cutting crystal face. The swelling of the material is generated beside the abrasive grain. The range and height of swelling are increased gradually and kept invariant after chip formation. The deformation of workpiece material contacting with grain edge is very severe. Therefore the biggest residual stress appears at the grain edge of the groove.

Abstract: Single-grain grinding test plays an important part in studying the high speed grinding mechanism of materials. In this paper, a new experimental system for high speed grinding test with single diamond grain is presented. The differences of surface topography and chip morphology of Inconel 718 machined by single diamond grain and single CBN grain were evaluated. The grinding forces and corresponding maximum undeformed chip thickness were measured under different grinding speeds. The chips, characterized by crack and segment band feature like the cutting segmented chips, were collected to study the high speed grinding mechanism of nickel-based superalloy. The results show that the grinding speed has an important effect on the forces and chip formation, partly due to the temperature variation. As the speed increases, the groove surface becomes smoother.

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: Three-dimensional cutting process of single grain in the shape of polygonal pyramid was simulated by coupled Euler-Lagrange method. The method makes the workpiece material free from its meshes. The material allowance can be removed without mesh separation criterion. The simulation results show that workpiece material flows to the side and front owing to the pressing of cutting plane. Chip flows out along the front of the grain upward. The deformation of workpiece material contacted with grain edge is very severe. Therefore there is large machining stress concentration at the contact zone of grain edge. It results in biggish residual stress and cutting temperature at the side and bottom of the groove. The contact stress at edge angle of abrasive grain is biggest. Therefore grain wear is severe in the position

Abstract: In the present study, grinding temperature was measured by using a foil thermocouple when granite was ground by SiC wheel. De-noised the temperature signals with soft threshold method base on wavelet transform was conducted to analyze the grinding process. Energy partition to workpiece was estimated to be about 10%~30% by matching the measured temperature to analytically value. The number of active grains was determined by counting the high frequency impulses in the measured temperature signals. The ratio of active grains to total grains was about 4.5%~6.1%. Based on the results, a formula was deduced for calculating the temperature of single grain in the grinding process.