Short Arc Milling Machining Electrode Loss Research And Optimization Based On Fuzzy PID

In face of the difficulty of high hardness,high strength,high toughness materials’ application fields and ranges becoming wildly at present,non-traditional machining opens up a new land with its unique advantages for the bottlenecks encountered in mechanical manufacturing industry.Short arc processing is included in non-traditional machining,which achieve material removal mainly using the huge electrical energy and explosion produced by positive pole and negative pole.Besides,the molten metal scrap is washed away by the gas-liquid mixing medium with certain pressure.At first,this paper analyzes the discharge mechanism of short arc machining,which can let us master the plasma channel formation principle and acquaint the process of workpiece material removal.At the same time,we observe the actual processing of electrode temperature changes by using Thermcamvision A40 infrared thermal imager.In order to avoid the overheating of the workpiece during short circuit,it puts forward the fuzzy control algorithm in the servo control system after comparing the advantages and disadvantages of different control methods.The starting point of this study is optimizing the short arc milling,reducing electrode loss as well as improving the quality of machining.Making experiments and reading literatures can let us find the main factors causing electrode loss including various electrical parameters(voltage amplitude,duty cycle and frequency),the selection of electrode materials,the state of the working medium as well as the size of the feed during normal processing.To explore the influence of diverse factors on electrode loss,the experiment uses the single factor analysis method.After setting the invariable parameters,it selects multiple sets of test parameters,and gets the processing status with electrode loss relatively little.But in the actual processing,because of the discontinuity of discharge parameters and the failure of the material to be eliminated in time,the short circuit is caused by the failure of the material.At this time tool electrode and workpiece material appear the "machining" during the abnormal processing,which will aggravate electrode wastage and reduce the workpiece quality.To avoid the situation that has been stated above,this paper proposes adaptive fuzzy PID control algorith with the electrical signal of the actual values and setting threshold value deviation,rate as the input of system,using the fuzzy rules adaptive adjustment of the output of the controller,and verify its feasibility of the mathematical model in Simulink.In view of the current signal acquisition,this articl uses the PCI-1716 data acquisition card through comparative analysis,with Delphi 7.0 as development tool,due to the processing by the electric current to determine the clearance between the tool and workpiece size.We use the signal generator SG2040 A send signals,and compare the waveform between oscilloscope and Delphi acquisition interface finding that two groups of waveform are consistent,which verify the feasibility of the acquisition system.