Modeling And Optimization Of Single-channel Scanning Velocity Based On Micro-energy Pulse Discharge

Electrical Discharge Machining (EDM) is capable of machining conductive materials because it has a non-contact, no macroscopic characteristics of cutting force. With the development of preparation methods of micro-electrodes, scanning machining technology of micro EDM plays an important role in manufacturing the high-hardness, low-rigidity and complex thin-walled parts, it becomes an indispensable part in micro fabrication technical field. However, its machining efficiency is low, which restrict its development. In view of this situation, this paper focuses on the analysis the scan speed, which has a great influence on machining efficiency. According to studying the micro energy single electrical discharge pulse, the matching model of scan speed is established and the scan speed is optimized. Through this method, an optimal scan speed can be found according to electrical parameter of electric discharge and other non-electric parameters, which can match with the erosion speed, thus reducing the probability of short circuit and airborne pulse, increasing the stability of process and improving machining efficiency. Concerning the problem, this paper carries out the following research:(1) Analyze the mechanism and processing characteristic of micro EDM. The erosion feature of single electrical discharge pulse is the base unit of electrical discharge machining, this paper analyze detailedly the process of micro energy single electrical discharge pulse include the generating and establishing of micro energy single electrical discharge pulse field, breakdown of dielectric, formation of discharge channels, transmission and distribution of energy, ejection of arc discharge products, and deionization process. This paper also discusses the polar effect, and the discharge characteristic of the anode which are in different discharge status. Through above analysis, the understanding of discharge status in micro EDM is becoming more profound and a conclusion which the workpiece should be positive in micro EDM can be obtained.(2) Simulation and experiment research of micro energy single electrical discharge pulse. An regular that erosion feature of micro energy single electrical discharge pulse with the polar, grain sizes and pulse width is obtained. The diameter, depth and erosion-volume of electrical pit will increase while the diameter-depth ratio will decrease with the pulse width increasing. The diameter, depth and erosion-volume of electrical pit are greater when workpiece is used as cathode, while the diameter-depth ratio is smaller in the same pulse width; The same material whose grain size is smaller is easier to be eroded by the single electrical discharge pulse, but the grain sizes have no obvious effect on the material removal when the grain sizes is not too small.(3) Establish the matching model of scan speed and optimize the scan speed. Based on the research of micro energy single electrical discharge pulse, the matching model of scan speed is established and a series of single-channel scanning experiments are carried out. The experimental results indicate that the matching model of scan speed is reasonably. A neural network is adopted to predict the optimal scan speed and experiments are carried out to verify the optimal results. The maximum relative error is no more than ten percent.According to above research, a method can be provided that an optimal scan speed can be found according to electrical parameter of electric discharge and other non-electric parameters in single-channel scanning machining of Micro EDM, thus increasing the stability of process and improving machining efficiency.