The Study Of Control System For Plasma Surface Hardening

Plasma arc surface hardening is a method of surface heat treatment. It makes high energy density plasma arc to heat the surface of material, which brings about the phase change and forms quenching layer. Plasma arc surface hardening can enhance the hardness and abrasion resistance on the basis of keeping its inner components in good toughness. Compared with induction heat-treat, flame heat-treat and laser surface hardening, plasma arc surface hardening technique has the advantages of simple apparatus, small size, easy operation, low cost and high heat efficiency. In developed industrial countries, the study of plasma arc surface hardening has stepped onto the stage of practical application. Outstanding results have also been achieved at home, but the practical application is rare. Therefore, the realization of the industrialization in plasma arc surface hardening technology is obviously beneficial both in economics and society.In actual production, the stability of the surface hardening effects are often influenced by the technique conditions (such as plasma arc nozzle and the burning of tungsten, etc. ) and the changes in shape of the work piece. So this paper starts form the reality and focuses on solving the problems as follows:(1) Establish a plasma arc surface hardening power supply system controlled by microcontroller to test and regulate the voltage, current and energy output over time in the process of surface hardening. By this way, practical problems such as melting caused by arc start and stop, heating electronic current impulse and work piece shape can be solved.(2) This paper uses microcontroller as the core of control and collects all the voltage and current signals in the surface hardening process. Then the microcontroller handles the data. By studying the changing law of main parameters in the process of surface hardening, experience of developing integral and intellectual power source specially used by plasma arc surface hardening is accumulated. Then with the program processed and the database built, the microcontroller realizes its control. (3) In order to keep the stability of plasma arc surface hardening controlled by microcontroller, the premier problem that must be solved is the anti-interference. In accordance with the need of practical research program, the surface of materials such as 45 steel, 2Cr13 42CrMoE 17-4PH QT600-3 are strengthened to build a database controlled by the microcontroller. This study lays foundation for expert system of plasma arc surface hardening.