The Study And Implement Of Automatic Control System For Plasma Spraying Based On PLC

With the continuous attention of the whole world on the environment, China has been enacted many policies to promote the progress of energy saving and environmental protection in recent years. As we all know, very serious direct economic loss has happened to every country only due to the aging of the equipments which abandoned simply because its surface is corroded or badly worn. In this social context, the spraying industry in China has developed very fast in recent decades, as one of the most active branches of spraying industry, plasma spraying also made great progress at the same time.Because of the hardware defect of traditional plasma spraying equipments, its stability, reliability is hard to be guaranteed, when implement the current regulation, the traditional circuit boards unable to work well for a long time for some problems happens frequently, such as short-circuit and open circuit. So short service life, difficult to repair and other series of difficulties has been caused to traditional plasma spraying equipments.On the basis of traditional plasma spraying equipment, the paper focus on the transformation of its control system. Take the programmable-logic-controller which with analog output port as the core processor not only to control the peripheral devices, but real-time adjust the current. On the other hand, the touch screen technology can achieve the visual effects of man-machine dialogue. The contents of this paper include four parts:First, theoretical studies:the mechanism of plasma spray coating formation, LC oscillator circuit schematic, high-frequency ignition principle, the principle of magnetic saturation controllable reactor to adjust current. Second, the plasma spraying automatic control system hardware and software design:the first are consist of the PLC control cabinet, the transmitter, and the board which used to adjust the current; the other includes the touch screen and PLC programming. Third, Magnetic saturation controllable reactor modeling and simulation:start from basic mathematical theory to establish the MATLAB simulation model. Forth, put the real control system into practical application, get the data of experiments, analyze the. results and solve the problems that appear during the time. After transformation, for the first, the control system is not only effective to cut off the high frequency signal after ignited to reduce the adversely affect, but real-time monitoring the key variables of the system and protect the system effectively when it is abnormal. In addition, because of the application of touch screen technology, a significant reduction of the total cost has been saved; for the reason of closed-loop control strategy, a precise control of the main circuit current has already achieved.The results shows the control system that been transformed has good reliability and operability, which realize real-time control, for the most important, it has a good spraying effect and achieve the expected purpose of the transformation.