Research On Precision Pulse Power Supply And Process Of WEDM-HS

With the rapid development of modern industry, products in many fields aredeveloping towards high-grade, precision and advanced. And the application of highstrength, high hardness, high brittleness and other difficult-to-machine materials isbecoming more and more widely. Owing to the unique processing advantages of WEDM,it has been an extremely important and irreplaceable means of processing precision partsin aerospace, mold and other fields. The pulse power supply is the key component of theWEDM, which directly restricts the improvement of WEDM overall performance. Atpresent, the pulse power supply used in industrialization WEDM-HS in the domestic,whose processing surface quality and machining accuracy are low, is generally applied torough machining and can not meet the requirements of the precision machining for largethickness parts. Therefore, in order to achieve precision machining of WEDM, there is agreat of significance to research on precision pulse power supply and its processexperiments for reducing production cost of parts and promoting our country’s WEDMprocessing technology.On the basis of comprehensive analysis of development status of WEDM precisionpulse power supply at home and abroad, it is analyzed about the effect of pulse powersupply on processing surface quality and processing speed and characteristics of WEDM-HS. Aiming at precision machining for workpiece, a multi-mode precision pulse powersupply is designed, which is suitable for multi-cutting and realizes semi-fine andfinishing machining. Different power modes processing experiments which are based ondeveloped precision pulse power supply are carried out to optimize the processingparameters.In this thesis, a multi-mode precision pulse power supply based on MCU and doubleCPLD is designed and its electric parameters can be widely adjusted. MCU and doubleCPLD constitute high-frequency pulse signal generator and selection unit of power mode,resistors, capacitors, open circuit voltage and discharge state data processing unit.Different pulse power supply modes can be chosen by selecting different power switches,resistors and capacitors and power modes includes TR mode, TC mode, TRT mode, TCTmode and TRC mode. Through debugging, the pulse power supply can output pulsewaveform whose pulse width is0.08μs-20.4μs and pulse interval is0.08μs-20.4μs,which provides conditions of WEDM precision machining.Experiments are carried out to study on effects of various electrical parameters(pulse width, pulse interval, open circuit voltage, capacitor) and non-electricalparameters (wire speed, feed rate, workpiece thickness, offset) on processing surface quality under different power modes based on developed WEDM-HS precision pulsepower supply. Orthogonal experiments are carried out to optimize multi-cuttingprocessing parameters. Then five-cutting experiments are conducted using the optimizedprocessing parameters, obtaining that the best surface roughness reaches0.68μm undercontrollable resistance mode pulse power supply and0.96μm under controllable RCmode pulse power supply and0.89μm under combination controllable RC andcontrollable resistance mode pulse power supply.