Research On The Theory And Technique Of Electrical Discharge Truing (EDT) Process

Work-pieces with complicated shape, made of high-performance hard-brittle materials such as optical glass, ceramics, semiconductor and artificial crystal, have been applied significantly in the fields of aviation, e.g aerospace, optics, electronics, automobile, military facilities etc. Those work-pieces need higher accuracy and lower surface roughness. The ultra-precision machining for work-pieces with complicated profile can be achieved by precision Electric Discharge Truing (EDT) with cast iron-bonded diamond grinding wheels, which greatly improves the truing efficiency.In this dissertation, some dressing technique for diomand wheel and the principle of precision EDT technique have discussed, furthermore the experiments for the efficiency and accuracy of EDT with cast iron-bonded diamond wheel have carried out. The dissertation adopted the single- parameter method to analyse the parameters which affect the efficiency of EDT process for cast iron-bonded diamond wheel with four types of medium: mist, water, air, compress air, also some machining parameters e.g. electric current, electric voltage, the spayer's position and moisture content in mist also have been discussed in this paper. From the experimental results, it can be seen that the material removed rate is increased along with electric current and electric voltage, the fastest EDT efficieny in mist can be got because material on the surface is removed efficiently by the super high temperature caused by the plasma in EDT process.Some experimental researches on the accuracy of EDT process with cast iron-bonded diamond wheel have been done in this dissertation. Some machining parameters e.g. four types of medium: mist, water, air, compress air; electric current and electric voltage have been discussed for the accuracy of EDT process. From the experimental results, it can be seen that the accuracy despressed along with electric current and electric voltage, the best surface roughness in water can be got because water can take most quantity of heat.Using profile modeling method, the profile of work-piece can be copied to a cast iron-bounded diomand wheel by optimizing EDT process. The profiles of cast iron-bonded diamond wheel and electrode were analyzed using software of MATLAB with the edge measure arithmetic operators. It can be found that electrode had the consistent profile with the designed shape of the eletrode and the grinding wheel after truing process, also the consistent profile of the work-piece with a designed shape has been got by the optimized EDT process. The angle errors of the cast iron-bounded diomand wheel with EDT process were about 0.8°, and the dimension error of the wheel was 0.15mm in the top of the wheel. Therefore the efficiency and precision EDT process can be achieved by the optimized machining parameters.