| Since the middle of the 20th century, aerospace, atomic energy, military industry and other cutting-edge technology have large demand for high temperature alloys and other special steel, which makes the vacuum metallurgy developing rapidly. Vacuum metallurgy is entering a new phase and being more and more automatic. Based on this, this thesis proposes a multi-functional vacuum induction furnace computer control system, on the background of an Institute actual project, and then researches on the refining temperature control method.The control system adopts a two-level control system with PC upper computer at the management level and PLC at the process-control level. PC utilizes industrial control computer that it uses WinCC to configure the software programming and to realize Human-Computer Interaction. PLC is used to implement the main control function, which chooses Siemens S7-300 series production with the core unit of S7314C PN/DP as CPU. The system adopts distributed structure and use advanced field bus to achieve automatic control.In the process of vacuum induction furnace melting, it is important to control the refining temperature precisely. The molten steel temperature, however, is always changed suddenly, which the conventional PID controller is hard to adapt to. To solve this problem, this paper presents the hybrid fuzzy PI controller. The superiority of the controller has been confirmed by the simulation,which lay a solid foundation for using actual production next. |
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