Research On Control System And Welding Process Of High Frequency Micro-Plasma Arc Welding Machine

The plasma arc welding is always called the micro-beam plasma arc welding whenthe welding current is below30A. Micro-plasma Arc Welding is a perfect welding processto weld ultra-thin and ultra-fine structural parts due to the high restraint degree and energydensity. Now micro-beam plasma arc welding has been widely used for welding stainlesssteel, copper, titanium, tungsten and other materials in the electronics industry,instrumentation, aerospace and other fields. In this paper, the micro-plasma arc weldingmachine control systems and welding processes was studied. The study mainly containsthe analog control system, digital control systems, ultra-small current stability of outputand process experiment.In this paper, the main arc inverter control system of P-MPAW, the main arc invertercontrol and drive system of P-MPAW, arc control system of P-MPAW are three parts tostudy the analog control systems of Micro-plasma arc welding machine. Circuit designand debug analysis of every parts was carried out, and ultimately the analog control systemof micro-beam plasma arc welding machine which consistent with the design requirementswas acquired. Followed by the study of the digital control system of micro-beam plasmaarc welding machine, from the electrical principle of hardware, principles of software,testing commissioning, operation flow. Control system of high-frequency micro-plasmawelding machine which achieving all-digital technology, can realize two kinds weldingprocess of DC and pulse current-current type and a variety of welding parameters, weldingfeatures adjustable was successfully developed.The specific technical research on output of high-frequency micro-plasma arcwelding ultra-small current is respectively welding power source, welding torch structure,and high-frequency pulse. Arc power supply composed of main arc power supply and small-arc power supply, solving the problem separately from the output of weldingcurrent in a larger range (maximum current is375times the current minimum) and asimple pulse-width modulation is difficult to achieve precise control over the current.Study found that diameter of welding torch nozzle has a great influence on the mostcritical arc length when stability combusting and the difficulty of arcing. With the nozzlediameter increasing, the largest critical arc length while stability combustion is increased,but arcing becomes more difficult. Pulsed arc welding current has an important influenceon the reliability and stability of the arc. Pulse welding current will result in changes inradial distribution of charged ions, increasing the arc pressure of arc column, therebyenhancing the arc stiffness, energy density increases and arc stability. The part of the studyon Welding process carried out high-frequency micro-plasma arc welding experiments onultra-thin and ultra-fine materials such as stainless steel screen mesh with wire diameter of0.2mm and0.05mm thick titanium foil successfully. On the basis, welding quality causedby various process parameters in the welding of ultra-thin and ultra-fine materials wasanalyzed. In addition, the causes of welding defects were analyzed and preventivemeasures were put forward. In this paper, the study on micro-plasma arc welding processprovides great significant guidance to its application and popularization in the field ofwelding ultra-fine and ultra-thin materials.