Research On The Characteristic Of High-efficiency And Thin-wire Machining In HSWEDM

Both high-efficiency and thin-wire machining are important research fields in HSWEDM and have been widely used. However, the burnout phenomenon of high-efficiency machining and wire fracture of thin-wire machining are serious problem which can hardly be solved. Firstly, I study the burnout phenomenon and find that the dynamic characteristic of the medium within the gap plays an important roll which is a direction of my study to solve the problem of burnout and fracture. The main research contents are as follows:(1) The fundamental reason of burnout in high-efficiency machining is studied. When the dielectric is gasified by the high energy, the dielectric becomes too insufficient to cool the melting debris which attaches to the side walls of gap and cause the burn stripes.(2) The relationship between the evacuation of the debris and the ability of bringing the cooling liquid by the wire is studied. The way of evacuation is studied through experiment and find the debris largely evacuates from the back of gap. The relationship between the accumulation of the debris and the flow of the cooling fluid is analyzed by the mathematical model. It is found that the more fluent the debris evacuate, the faster the dielectric flow.(3) In order to reduce the burnout phenomenon, the method of machining assisted by magnetic field has been proposed. A magnetic field which parallel with gap direction can attract iron debris, so that it can help debris evacuate from the back of gap and cause less burnout.(4) According to the characteristics of high resistance and low tension in thin-wire, the machine tool had been redesigned and the machining process is studied. High resistance will affect control system and make it unable to identify the signal of wave. Low tension will increase the bend of the wire. Added with the uneven forward and reverse friction coefficient, it can cause cutting stripes in the Y direction.(5) The reason of the wire fracture is researched and summarized. The machining assisted by magnetic field is proposed. The reason of wire fracture is that the processing is not stable and the discharge is concentrated on a location of the wire. One of the reasons for the above problems is the accumulation of debris. With the aid of proper magnetic field, the debris can be evacuated, which reduces the probability of wire fracture.