Design And Implementation Of Fuzzy Temperature Control System For Multi-Purpose Furnace

The heat treatment,one of the basic technology,with the rapid development of Chinese machinery manufacturing industry,has been more and more important in recent years.The controlled atmosphere multi-purpose furnace is widely used in heat treatment equipment,and there are many traditional technical problems.The first problem is time-delay,because the wall of multi-purpose furnace is thick and the volume is large.The second problem is nonlinear,since there are many outside disturbances during the running of multi-purpose furnace,such as the heat generated by the rotation,different effect on hot air circulation between full-load and half load.The third problem is that the model is hard to build,as it is influenced by the complex working conditions,heat convection,heat radiation,and the uncertainty of the external environment.Firstly,this paper analyzes the structure of the carburizing automatic production line,which includes the multi-purpose furnace,tempering furnace,washing machine,load table,unload table,and stores.The multi-purpose furnace is the most important part of the line.It is consist of heat chamber,quenching chamber,oil tank,conveying system,and atmosphere panel.Carbon potential(Cp)is the key parameter of multi-purpose furnace,and temperature is another key parameter in the carbon potential control and heat treatment process,so the precise temperature control is very important.Secondly,this paper introduce the design of the furnace temperature controller base on variable-universe fuzzy control.It is a kind of domain shrinkage of high precision fuzzy controller.It has some advantages that are the low dependence on the model of control object,besides that the dynamic performance and steady-state performance are good.Compared with the general fuzzy controller,the performance of variable-universe fuzzy control is much more better.This paper introduces the design which is based on the heating chamber of the furnace temperature,including the method and the detail design process.Then,based on the requirements of the furnace and the control requirement of controller,this paper introduces the selection scheme of the control system.According to the furnace characteristics,and taking into account of the factors,such as cost and efficiency,it chooses a control system with main hardware based on PLC,distributed IO,and touch screen.The distributed IO collects the IO signal and executes the control signal.PLC is used as the controller to carry out the process control,logic control and so on.HMI is used to monitor the status and parameters setting.Then this paper introduces the hardware system construction,the key components selection and software system design.The software includes the PLC and HMI design.Finally,with the data from the established testing platform,this paper analyzes the effect of the variable-universe fuzzy temperature controller for multi-purpose furnace temperature,which is compared with PID and fuzzy control.What's more,it lists the advantages and disadvantages.By investigating the reasons of the weakness,we can find a basic direction for the better controlling of the multi-purpose furnace temperature control system.