Research On Mechanism Of Mechanical Lapping Of Natural Diamond Tools And Key Technologies Of Manufacturing Micro-milling Tools

At present,in the fields of micro-electronics industry,biomedical equipment,electronic communication,precision instruments,aerospace and other fields,the demand for micro-devices and structures with certain shape accuracy,size accuracy and surface quality requirements is developing rapidly.Micro-milling has become the main technology for processing high-precision micro-parts because of its high efficiency and the ability to process complex three-dimensional surfaces.In order to obtain super-high machining accuracy and super-smooth surface,high precision diamond micro-milling tool is a necessary condition.The mechanical lapping technology of diamond turning tool provides a certain research basis for the preparation of diamond micro milling tool.However,there are some problems different from diamond turning tool in the lapping technology and high-precision assembly of diamond micro-milling tool,which restrict the development of diamond micro milling tool preparation technology.In this dissertation,based on the anisotropy of phase transformation in the mechanical lapping of single crystal diamond,the orientation and fixation scheme of the rake and flank face of the micro-milling tool head are designed,the mechanical lapping technology and assembly method are studied,and the preparation of high-precision diamond micro milling tool is completed.The specific research contents are as follows.By using high resolution electron microscope and electron energy loss spectrum,it is observed that the phase transition is anisotropic.The mechanism of mechanical lapping of diamond crystal is revealed.The mechanism of mechanical lapping of single crystal diamond crystal with different crystal directions is explained from the perspective of crystallography by using molecular dynamics.It is considered that the mechanical lapping efficiency of diamond crystal is largely determined by the proportion of sp~2 hybrid carbon atom and amorphous sp3 hybrid carbon atom in the machined surface and lapping chips.The explanation lay the theoretical foundation of this research topic.Based on the experimental phenomenon that the mechanical properties of {110} crystal surface can be significantly improved after low-temperature annealing heat treatment process,the evolution rules of different carbon phase composition and low-temperature annealing of phase change layer after mechanical lapping are studied by molecular dynamics,including the extraction of ordered sp~2 carbon atoms,the change of atomic density and the evolution diagram of carbon atom structure before and after annealing,etc.We found that in the {110} plane after mechanical polishing,there are more sp~2 hybrid carbon atoms in the surface phase change layer,and the number of ordered sp~2 hybrid carbon atoms are gradually increased with increasing time of heat treatment in a low temperature annealing.Based on this theory,the crystal orientation scheme of the rake and flank face of the single crystal diamond micro milling tool is proposed,and the fixing methods of the welding type and the clamping type milling tool head are designed.The diamond micro milling tool thus prepared not only improves the lapping efficiency,but also greatly improves the performance.In view of the establishment of the mechanical lapping technology of "cutting edge formed by flank face" for the welded diamond micro-milling tool,the effects of the process parameters such as diamond grit size,lapping speed,feeds per time,lapping compressive force,reciprocating stroke,reciprocating frequency and pendulum speed on the micro-chipping,arc waviness,flank face roughness and blunt radius of edge were studied.Using a preferably lapping process parameters lapped out a no chipping and good edge quality micro-tool blade.The results of lapping experiments show that the arc waviness of the circular edge of R {100}F {100}diamond micro-milling tool can reach 40 nm,the flank face roughness of the is Ra 0.7 nm,the radius of the blunt edge is 23.4 nm,the arc waviness of the circular edge of R {100}F {110}directional diamond micro-milling tool can reach 50 nm,the flank face roughness of is Ra 1.95 nm,and the radius of the blunt edge circle is 29.3 nm.Aiming at the problem of precise assembly of diamond micro-milling tool inserts and tool holders with mechanical clamping,an optical alignment system based on double CCD and an optical alignment platform with 6-DOF are built.The high precision positioning assembly of diamond micro-milling tool inserts and handle is realized,which provides key technology support for manufacturing high quality diamond micro-milling tool.Meanwhile,Aim at milling performance and tool life,Micro-milling experiments and micro-milling tool wear experiments were designed,it provided key technical support for manufacturing high quality diamond micro milling tool.