Research On The Discharge Characteristics Of Wedm For Semiconductor Crystal And The Bent Wire Electrode Control

The semiconductor is high brittleness and low toughness, so traditional technology is difficult tomachine it. While, electrical discharge machining (EDM) uses electrical power to remove materialsother than using the mechanical power, so it could machine materials no matter their rigidity andintensity. The traditional materials machined by EDM are required to be good conductive, while, theresistance of the semiconductor is3～4times higher than metal materials. So the characteristics of thesemiconductor in EDM are analyzed.The bent wire is referred to: when process the semiconductor with the traditional servo controlsystem of WEDM machine tool by using the inappropriate parameters, the electrode wire will be bentand contact with the work piece, but there is still some discharge in the process. If the process goes on,the cutting track of the work pieces will be changed and become harm to the whole process. For this,the paper researches the control of bent wire in the process, and put forward a bent wire detectioncontrol system used in the processing semiconductors by WEDM. The major works are as followed:(1) Both the discharge model of metal and semiconductor are established, and the EMDmechanism and the discharge conditions are analyzed according to the wave shape produced bymachining the semiconductor. Finally the bent wire discharge condition is put forward.(2) The characteristics of the position for the electrode wire in different discharge conditions arestudied. A new method, which is based on the position detection of wire electrode, to control bentwire electrode in the WEDM of the semiconductor is put forward. Therefore, the control system isdesigned and the major models of the system are described, including the detection signal model,interference signal model, and interrupt signal model. The factors which affect the control system arealso considered. Finally, we discussed the application the control system.(3) The effects of electrical parameters, composite cooling liquid and the thickness of the workpiece on the material removal rate of monocrystalline silicon in WEDM are researched. By comparingthe bent wire control system with the original control system according to the surface roughness of thesemiconductor machined by the two systems, it is proved that the bent wire electrode control systemcan effectively control the bent wire when machine the monocrystalline silicon by WEDM, improvethe removal rate, and make the silicon have a good surface roughness.