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Research on Key Techniques of Micro Machining of Micro-Structure on Hard and Brittle Non-Metallic Materials

Author: WangDan
Tutor: ZhaoWanSheng
School: Shanghai Jiaotong University
Course: Mechanical Manufacturing and Automation
Keywords: Micro-EDM Micro ultrasonic machining Microcrystalline mica ceramic Polycrystalline diamond Micropore Micro nozzle
CLC: TG661
Type: PhD thesis
Year: 2011
Downloads: 211
Quote: 0
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Abstract

Microfabrication of hard and brittle non-metallic material has been the difficulty in the machining. Microcrystalline mica ceramic (Microcrystalline-mica-ceramic, referred MCMC) and polycrystalline diamond (Polycrystalline Diamond, PCD) is typical and has broad application prospects hard and brittle non-metallic materials. Microcrystalline mica ceramic as the representative of a ceramic material having excellent insulating properties, high temperature and low thermal conductivity and other properties, its thermal conductivity is less than one tenth of the silicon material, such as the combustion chamber and the nozzle of the microthrust material, can greatly reduce the heat loss of the thruster system. Superhard polycrystalline diamond material has excellent characteristics of uniform high hardness, high wear resistance and strong corrosion resistance, very suitable for microporous parts in the aerospace, automotive and electronics industries in a broad application prospects. In this paper, a fine ultrasonic machining (Micro Ultrasonic Machining micro-USM), and micro-EDM (Micro Electrical Discharge Machining, referred to as micro-EDM) technology, microcrystalline of mica ceramic and polycrystalline diamond microfabrication research. Study the block electrode discharge grinding (Block Electrode Discharge Grinding, referred to BEDG) and cutting edge electro discharge grinding (Edge Electrode Discharge is Grinding, EEDG) method of micro-EDM and micro-the ultrasonic machining tools online preparation techniques . BEDG study proposed beveled irregular pieces of electrodes of the anti-copy type machining methods, and this method as the roughing process of the rotary body has a tapered profile, in order to improve the processing speed of the rotary body of the special morphology fine. CNC machining technology planning tool feed trajectory EEDG study, combination tool electrode wear compensation method, flexible and prepared with different three-dimensional outline of the rotator. Microcrystalline mica ceramic material, for example, to solve key technical problems in the processing of micro Laval nozzle. Adopt the combined method BEDG and EEDG fast and accurate online preparation of a fine ultrasonic machining tools. Orthogonal experiment method to study the influence of processing parameters on the micro ultrasonic machining tool volume loss rate, and optimize the process parameters. Through the flow characteristics of ultrasonic machining work liquid abrasive proposed priority the necessity of processing the pre-through hole in the micro-Laval nozzle during processing, and in microcrystalline mica ceramic material processed throat diameter of 170μm micro pull Fava nozzle. The PCD material micro-EDM process experimental research in the the PCD material physical characteristics of its micro-EDM performance analysis based on. The experimental results show that the PCD material more suitable for fine EDM attachments tools on the adsorption of the protective effect, the use of the processing of the workpiece then negative. Adsorbed amount of attachments, only when the tool in the machining of the workpiece then negative, the protective effect of the attachment of the more obvious, can be effectively improved material removal rate (the Material Removal Rate, referred to as MRR) also reduce the tool electrode relative loss rate (Relative Tool Wear Ratio, referred TWR). Conversely, if the tool electrode is adsorbed on excess of attachments, then make the processing into a low MRR and a vicious cycle of high TWR, and processing the aperture is too large pores. According to the experimental results to find a better range of processing parameters, and a set of optimized processing parameters, and machining a diameter of the fine through-holes of 145 μm and the depth of 650μm. Micro-EDM process research of the PCD material basis, by adding ultrasonic vibration on the workpiece, and may further improve the performance of PCD material Micro-EDM. Working fluid cavitation bubble closure process as well as the working fluid particle motion process mechanical calculations. Under different processing parameters the PCD material ultrasound the auxiliary spark microporous processing experimental. Experimental studies have shown that the ultrasonic vibration to improve the state of the discharge process and shorten the duration of the arcing discharge frequency; ultrasonic vibration will reduce the adsorption on the tool electrode attachments, the processing of both positive and negative implications, choose the ultrasonic amplitude (2μm) in the PCD ultrasonic vibration assisted EDM, micro-EDM range of parameters for PCD material to expand and improve the processing performance and the quality of the machined surface.

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