Development Of Pulse Power Supply For Wire Cutting Processing Based On Effective Pulse Width Strategy

As an important branch of special machining field,Wire cut Electrical Discharge Machining(WEDM)is mainly aimed at some materials with high hardness and complex shape.WEDM has been widely used in automobile manufacturing,mold manufacturing,medical instruments and aerospace and other fields.WEDM system mainly includes high frequency pulse power supply,wire storage cylinder,machine bed,electrolyte circulation system,servo motion control system,etc.Among which the performance of pulse power supply directly affects the stability of wire cutting process and the surface roughness of machined materials.This paper analyzed the mechanism of WEDM and the influence of single pulse discharge energy on the machining process.Based on the effective pulse width which can produce metal erosion during wire cutting,a composite pulse machining method is proposed.In order to eliminate the short circuit in the machining process,a compound pulse with small pulses is output to control the switch tube turn-on and turn-off.The feasibility of this machining method was verified by simulation analysis.The transistor resistor-type pulse power supply is designed as the pulse power source of the discharge main circuit.The hardware part of the power supply mainly includes the main controller MCU module,the isolation drive and power amplifier circuit,the gap data detection and processing circuit and the serial communication module.The software part includes the main program,the initialization program and the serial communication program.At the same time,the communication protocol of the entire system based on Modbus is developed,the working interface of WEDM system and the address assignment of each key are designed,and the human-computer interaction design of real-time display of discharge parameters and online adjustment of machining process is completed.Secondly,this paper analyzes the source of the pulse power supply in detail,and takes corresponding anti-interference measures from both software and hardware,the prototype of the pulse power supply is also completed.By testing the output waveform of each module of the developed pulse power supply and conducting the gap short circuit simulation experiment,the results show that the designed pulse power supply can achieve the desired effect and can be used in WEDM.The composite pulse power supply is compared with the common pulse power supply in the discharge machining experiment.The effects of the two pulse power sources on the surface roughness and removal rate of the processed materials are compared under different discharge current,pulse width and pulse interval.Through comparative experiments,it is verified that the composite pulse power based on the effective pulse width is better than the common pulse power in the machining performance,which can improve the machining stability and ensure the lower surface roughness of the workpiece.