Grinding Wheel Topology Modeling And Grinding Simulation By Discrete Element Method

As an important finishing method, grinding plays a vital role among all modern manufacture methods. However, it is still a’black art’because of its high cutting speed, strong randomness, complicated grit-workpiece interaction and hypercomplex material behaviors in contact area. With rapid development of computer technology, simulation has gradually becoming a powerful tool when researching grinding process. This is because the strong capability of simulation when describing highly-dynamics process, which is very suitable for conducting study about fast, complicated and undetectable grinding.The so-called grinding simulation generally contains two parts, modeling of grinding wheels and simulating grinding, both of which have already received wide discussion. But, all existed grinding wheel modeling methods and grinding simulation methods are established on continuum-assumption, i.e., they all assumed that grinding wheels are continuum, without microstructures like blowholes, binders and so on, and simulate grinding wheels behaviors based on continuum-material-behavior-theories, which is NOT the same as the fact.To solve aforementioned problems, this paper tries to use a discontinuum-based, grinding-wheel-structure-describable, mesh-free simulation method, the discrete element method (DEM), to model grinding wheel and simulate grinding. This work also discusses the modeled grinding wheel and simulation results. And to validate this new method, this study also does verification experiments. It shows that, modeling grinding wheel and simulating grinding by DEM can not only gains similar results with experimental ones, which can validate DEM’s accessibility, correctness and precision, but also can obtains some amazing data, which other methods can not, like forces exerted on binder during grinding process.Introducing DEM into grinding research can not only supplement grinding simulation technology at mesoscopic level, breakthrough limitation of all methods when describing discontinuum-like grinding wheel, but also can be very promising when talking about grinding wheel production formula, grinding wheel preparation technology, the wear of grinding wheel and life predicting, the areas of which relates closely to grinding wheel microscopic structure.Some main accomplishments and creative points of this study are:(1) This study introduces DEM into grinding. And considering grinding characteristics, some problem-solving methods during conducting DEM grinding wheel modeling and grinding simulation.(2) Because there is no mature economic DEM simulation software, this paper use a method, which is compiling custom function subroutines by C++ language and doing preprocessing and postprocessing by EDEM software, to conduct DEM grinding wheel modeling and grinding simulation.(3) When modeling DEM grinding wheel, this paper proposes to use truncated octahedron as SiC grain geometry representation, based on experiment detection. This work also suggests truncated octahedron size distribution law based on experiment measurement.(4) Because there is no relevant DEM data, this paper conducts calibration experiments, which includes unconfined compression test, Brazilian test and three-point bending test, and discuss the results. This might provide fundaments for following DEM grinding study.(5) This paper simulates grinding process and deeply analyzes chip-formation process and forces exerted on binders, which illustrates DEM’s advantage when researching grinding.(6) This paper conducts validation experiments and from two major aspects, machines surface quality and grinding, and four minor aspects, machined surface roughness, machined surface 3d profile, normal grinding force per grinding wheel width, tangential grinding force per grinding wheel width, compares simulation and experiment results, which validate DEM’s accessibility, correctness and precision.