Computer Control System Design And Research On Drop Short Control Method-for Vacuum Arc Remelting Furnace

Vacuum Arc Remelting Furnace(VAR)is a very important equipment in producing titanium and its alloys of high quality.And it can also be used for smelting steel.With the rapid development of our country's economy,demands for high quality titanium and alloy stell are increasing sharply.The computer control system of VAR our country designed can be used to melt titanium,but can not melt steel of high quality.The VAR our country need always bought from abroad,it is very important to reach on the VAR and it's computer control system.This paper designs a computer control system of VAR based on the projuct of an institute.Moreover this paper researches on the drop short control method to improve the control accuracy of gap length.Firstly,the characteristics and equipment of VAR are introduced,and then the computer control system of VAR is designed.The computer control system is composed of upper and lower computer.The upper computer is an industrial personal computer.It uses WinCC to configure the software programming and to realize Human-Computer Interaction.The lower computer is used to control the whole system,which chooses Siemens S7-300 series production as controller.The system adopts distributed structure and use advanced field bus to achieve automatic control.The stability of gap length has a great influence on the quality of ingot.The traditional method uses arc voltage to control the gap length.This method is simple and convenient,but is not very accurate,especially in steelmaking.So this paper reaches on the drop short phenomenon in the melting process to control the gap length.And in order to adapt to the actual production model,which is nonlinear,time-varying,the fuzzy self-tunning PID controller is designed.At last,Simulink is used for simulation research.By comparing the simulation results of fuzzy self-tunning PID controller and conventional PID controller,it verifies the superiority of the intelligent controller and lays a solid foundation for the application of real production.