Research On EDM Of Silicon Crystals Based On Closed-loop Pulse Power Source

Today,with the rapid development of science and technology,semiconductor materials are widely used in various high-tech fields.However,its special shape processing is difficult to achieve using traditional machining methods.In the process,silicon crystals are easily broken,and the processing quality cannot meet the requirements.EDM has the characteristics of no macro stress,which can be used as a necessary method for the complex shape processing of silicon crystals.However,due to the special properties of silicon crystals,the traditional EDM servo control systems have failed,and the continuity of EDM process of silicon crystals is affected..This subject firstly analyzed the electrical discharge machining mechanism of silicon crystals to determine the reasons why it cannot be continuously processed;Through experimental analysis,the relationship between pulse width,pulse interval,sampling frequency,feed rate and discharge probability was explored,based on this,a closed-loop controlled pulse power source based on discharge probability detection and a dual feedback control system were designed and built,and they are applied in actual processing,under the condition of optimizing parameters,the quality and efficiency of EDM of silicon crystals were improved,and the large thickness and complex shape cutting of silicon crystals were finally realized.The main work of this article is as follows:(1)Developed a closed-loop pulse power source based on the discharge probability detection.The components of the closed-loop power source were optimizd.The overall process of the closed-loop controlled system was designed,and the control algorithm was also optimized.The pulse power source can adjust the output parameters based on the real-time discharge probability.(2)An experimental system suitabled for EDM of silicon crystals is designed,The electrical discharge machining characteristics of silicon crystals are explored.The experimental data and theoretical models are combined to analyze the reasons why the silicon crystals cannot be continuously processed.The arc curved hole EDM of monocrystalline silicon crystals is realizad by the closed-loop power source and the methods to improve the effect of chip removal between electrodes.(3)The effects of pulse width and pulse interval on parameters such as discharge probability,surface quality,and machining efficiency were studied.Based on this,the pulse interval feedback method of the closed-loop controlled power source was determined.According to the fit between pulse interval and discharge probability,a pulse interval control algorithm was designed.This closed-loop pulse power source was used in the actual processing,and the processing parameters is optimized.The straight-line large thickness cutting of silicon crystals is also realized.(4)A feedback control system with dual adjustable pulse interval and feed speed was designed,which was tested by the silicon crystals wire-cutting EDM.The surface quality of the workpiece after cutting was improved by 41.4% compared with ordinary machine tools,and the processing efficiency increased by 142.2%,and finally realized the complex shape cutting processing of silicon crystal.