Study On The Micro-milling Mechanism Of Glass Based On Simulation By Discrete Element Method

Micro-milling is one the ways of micro-cutting techniques most widely used. Glass is thebrittle and hard material with processed mechanics far more complicated than ductile materialdue to its physical and mechanical properties. While ultra-sophisticated cutting and milling ofthese materials, the machined surface can be fractured when the processing parameters is notvery reasonable. So there is important theoretical significance and practical value tosystematically studying its machining mechanism and technology. In this paper, both discreteelement method simulation and experimental studies have been carried out to have a research onmachining process of glass. The main contents are as follows.First, the two-dimensional discrete element method is applied to micro machining of glass.The tests of uniaxial compression, brazilian split and three-point bending are adopted to get adiscrete element model matching the main mechanical properties with glass. Indentation, cutting,and micro milling processes are all simulated based on the model. From the crack propagation,stress variation and surface quality, it is found that different cutting thickness, cutter shape andspindle speeds largely effect on the mechanism of the glass in material removal process.Second, the three-dimensional discrete element method is applied in multiresolution methodto investigate the mechanical process for micro-machining of glass. The machining process issimulated by hybrid method in consideration of cutter and glass respectively as macro-rigidelement and micro-discrete element. During machining, the cutting force is loaded by rotatingfeed of the rigid cutter to induce structure change of the discrete glass to the form of deformationor mechanical energy. The simulation system can be used to analyze the slippage of discretegrain, the formation of crack, the propagation of machining force and its distribution, and theremoval of material.Finally, machining experiments of glass are carried out on an indigenously built micromilling apparatus. After a series of experiments by means of micro milling tools, energydispersion spectrum（EDS）analysis of surface composition of cutters is done. The wear patternsof cutters and the surface machining quality are also observed with different cutting parameterelectron scanning microscope (SEM). Meanwhile, the cutting force component is acquired through the Kistler dynamometer.This study may serve as full guidance for micro-machining in glass. It can also provide anew ways for research on machining mechanics.