Research On Discharge Gap Characteristics Of Energy-saving Pulse Generator And Multi-cutting Technology Of Wedm

Wire Electrical Discharge Machining (WEDM) plays an irreplaceable role in newproduct trial production, precision parts processing, mold manufacturing and other areas.Pulse power technology is one of the core technologies of WEDM, and its performanceaffects the machining quality of workpiece and stability of machine tool directly.Because of the low energy utilization of current-limiting resistor pulse generator, whichhinders the development of WEDM, energy-saving pulse generator has come to the hotspot for relevant scholars in recent years. Gap characteristics energy-saving pulsegenerator presents when it works is the basis of discharge status detection and CNCservo control, therefore, it is of great significance to study the gap characteristics ofenergy-saving pulse generator for the aim to give full play to its machining performance.Besides, as an important way to improve machining quality and machining efficiency, itis necessary to have a study on multi-cutting of WEDM.On the basis of analyzing the whole structure of the energy-saving pulse generatordeveloped by Harbin Institute of Technology independently, this thesis carries outtheoretical analysis and experiments study to its discharge gap characteristics,comparing the differences between energy-saving pulse generator and current-limitingresistor pulse power. In allusion to the specialty of gap voltage, current followedfloating threshold method is carried out to detect the discharge status, and its applyingperformance further explored. Multi-cutting technology database is establishedconsidering that multi-cutting is affected by more parameters and difficult to implement,which offers convenience when selecting machining parameters for multi-cutting.In this thesis, volt-ampere characteristics of energy-saving pulse generator when itworks is obtained, and ladder phenomenon of gap spark voltage is explained on thebasis of analyzing spark self-sustaining condition. Influence of pulse width, open circuitvoltage and workpiece thickness on gap peak current is studied. Conditions that floatingthreshold voltage should meet are proposed based on the analysis of gap voltage.According to theory model this thesis deduces empirical formulas on how to determinebias voltages of floating threshold, and the accuracy and reliability of floating thresholddetection method are verified through experiments. Experiments are carried out toanalyze the influence of peak current, pulse width and wire speed on machining efficiency and machining quality to single cutting. BP NeuralNetwork is establised toforecast the relationship between machining parameters and machining index, and itproves that the error between forecasting value and test result is less than±0.2μm and±3mm2/min for surface roughness Ra and machining efficiency respectively, whichmeans that this BP network has a well guidance for choosing parameters duringmulti-cutting. Finally, this thesis completes the programming of multi-cuttingtechnology database using VC++language, which achieves the basic functions of query,inserting, deleting and updating to multi-cutting technology parameters.