Control System Design And Research On Automatic Striking Arc Control Method For Protective Atmosphere Electroslag Furnace

The Electroslag Remelting (ESR) usually actualize under the atmosphere condition. Studies show that the oxygen content of alloy mainly depends on the concentration of deoxidizing elements and the oxide activity of the deoxidizing elements within the slag. In the past decades, people usually put deoxidizing agent (Al, CaSi, FeSi, Mg,,etc.) into slag bath to continuously deoxidizing molten slag. However, it will lead to a change within the component of molten slag, then, make the content of oxidizable elements in the remelting ingot different from the one in consumable electrode. A new craft has been proposed in the Electroslag Remelting area, which is applying Protective Atmosphere in the ESR furnace, and the equipment actualizing such process has been known as Protective Atmosphere Electroslag Furnace (P-ESR). This paper developed a computer control system in the light of the P-ESR technics.The control system includes PC and PLC. PC is responsible for Human-Machine Interconnection (HMI), and PLC controls the whole system. PC and PLC connects with Ethernet. PLC uses Siemens S7-300series production with the core unit of S7315-2DP CPU. Due to the application of distributed structure with advanced field bus, the system is easy for wiring, convenient to maintenance and utterly stabilizing.The production process of electroslag furnace mainly includes three parts:slag, remelting and feeding. In slag period, according to the difference striking arc, there are two methods: solid slag, liquid slag. Both methods play a significant rule in the producing process of ESR furnace. Furthermore, for solid slag striking arc, the key point is to control the changing of arc current in accordance with the preset process curve. But the physical and chemical reaction of striking arc of solid slag is very complex, hence, the number, physical shape and displayed position of arc material is random, and the continuous slag adding leads the arc current changing violently. In this paper, a controller is designed based on the algorithm of fuzzy PI according to the process characteristics of solid slag striking arc, as well as the simulation analysis. The simulation result shows that the control affect has been improved, which turn out to be a positive try-out to solve such problem.