Based On PLC To Develop The Computer Aute Control System Of The Of Magnesium-smelting Forge

This thesis takes the present control of the process of the fusion of magnesium-smeltingforge as its background, and its main focus is the prior human control, which could easilymake mistakes due to long time of operation. As a result of these mistakes, there would besome errors in the technology. Moreover, people may find a lot of difficulties suchas monitoring the operation state of the system, and recording the parameter of the technologyin human control. According to the requirement of the technology, we have developed an autocontrollment system which combines the PLC and the computer. The system is not only ableto make self-controllment of the operation process of the magnesium--smelting forge, but alsoable to do centralized and distributed administration.This thesis introduces the design of auto- controllment based on the computer and thePLC. It includes a lot of things such as the collection of the analogue quantity, thecontrollment of the multipath electromagnetic valve, enlargement from the single chipcomputer to parallel series ,the software design of the Upper and lower computer system, thedesign of the communication module ,and so on. Take PLC as the central controllment, thesystem collects the analogue quantity such as the temperature, the pressure, and kinds ofVolta parameters of the magnesium-smelting forge in real time .Because these apparatus areproduced in different factories, their communication interfaces differ from each other. Foreasy cabling and convenient maintaining, we have developed a system of enlargement fromthe single chip computer to parallel series, with which we could convert the level of TTL,CAN to RS485.Through RS485; the level is transformed to the PLC. After data processing,PLC would compare the data with the predetermined controllment parameter and then exportsit, and controls the valves of the transportation of the materials in 12 paths .PLC would then measure and control the electric voltage of the heated electrode, the control system of therectified circuit and the percent of vacuum in the heating forge.The thesis talks about a serialized net system which can be easily connected and thesystem can transport data quickly and safely. It discusses a lot of questions such as how torecord kinds of technologic parameters and the law in them, how to draw the bifurcation ofthe operating process according to the databank. Moreover, it studies how to achieve auto-preservation of dates such as temperature, percent of vacuum, electric pressure and current tomake a foundation for the improvement of the quality of the production. The question how touse the computer to modify the control parameter of the PLC and how to achieve thecontrollment of the opening and closeness of the valve and the accommodation of ups anddowns of the electric pressure by distensile hand operation. It analyses the way ofcontrollment of the operation of the system. And it makes a comparison between thecontrolling ways, one of which is independently controlled by PLC, and the other iscontrolled by the cooperation of PLC and the computer.