Study On Micro-milling Mechanism Of Sapphire With Multi-tooth Micro-edge Ball-end Milling Cutter

Sapphire has good chemical and optical properties,so it has important applications in aerospace,optoelectronics and national defense.However,due to its high mechanical and impact resistance,it becomes a typical difficult-to-machine material.The machining efficiency is extremely low,and the machined surface is prone to crack and damage,which restricts its wide application in aviation and aerospace.In order to solve this problem,this paper proposes to use multi-tooth micro-blade PCD ball-end milling cutter to micro-mill sapphire single crystal.Considering the size effect and the undeformed cutting thickness of single tooth,the milling force model of multi-tooth micro-blade milling cutter to process sapphire is studied by quasi-differential element method,and the great influence of cutting parameters on the surface quality and machinability of sapphire single crystal is analyzed.The research results of high-efficiency micro-milling sapphire single crystal are obtained through research,as follows:1.Based on the forming mechanism of sapphire micro-milling,the critical thickness of brittle-plastic transition in sapphire micro-milling is analyzed and studied,which is helpful to guide sapphire micro-milling to obtain high-quality surface.The geometric model of multi-tooth micro-edge PCD ball-head cutter is established,and the spatial geometric distribution of multiple cutter teeth is studied to provide model support for the later establishment of sapphire milling force model.Based on the theoretical model of undeformed cutting thickness of single tooth,the theoretical model of instantaneous milling force of multi-tooth micro-edge ball-end milling cutter is established according to the removal mechanism of hard and brittle materials.2.The simulation mechanism of high-speed micro-milling of sapphire crystal is studied by using finite element simulation software ABAQUS,and the milling force curve and surface morphology of sapphire after machining are fully considered in the finite element simulation process.The correctness of the theoretical model of critical thickness of brittle-plastic transition in sapphire micro-milling mechanism is verified by twodimensional orthogonal cutting simulation.3.By building a micro-milling test platform,the sapphire surface is micro-milled by using multi-tooth micro-blade PCD ball-end milling cutter,and the influence of different cutting parameters on milling force data during the micro-milling test process is studied,and the theoretical model and simulation data are compared to verify the accuracy of the model.By studying the surface integrity of the machined sapphire,taking the surface roughness as an index,the influence of the change of cutting parameters on the surface integrity of the machined sapphire under the orthogonal test was analyzed by means of three-dimensional morphology construction and scanning electron microscope.The research shows that the multi-tooth micro-edge PCD ball-end milling cutter can obtain good surface quality and low milling force.The milling force model established in this paper has an important guiding role in analyzing the influence of machining parameters on micro-milling,reducing the surface roughness of sapphire micro-milling and reducing tool wear.