Numerical Simulation And Control Method Of Cored Wire Injection Vermicularizing Process For Vermicular Graphite Cast Iron

With the development of high velocity and heavy load as well as frequent braking for the automobiles, the brake drum produced in original material can’t meet the growing design requirements. It is imperative to develop a new brake drum material with excellent comprehensive performance, such as high strength, high thermal fatigue resistance, high shock absorption as well as good thermal conductivity. Vermicular graphite cast iron shows a good comprehensive performance of both ductile cast iron and grey cast iron. Therefore, vermicular graphite cast iron is a better candidate for heavy truck brake drum production. In this paper, one-step cored wire injection is put forward for high performance vermicular graphite cast iron brake drum because of the difficulty of vermicularizing process. It has a great practical and stragetic significance for the application and development of vermicular graphite cast iron brake drum in high velocity and heavy load as well’as frequent braking for the automobiles.In this paper, the object of study was the metallic sheath of cored wire. The physical model for the dissolution process of the metallic sheath was built in laboratory. The dissolution process of the metallic sheath was studied by numerical simulation, which based on the basic theory of heat transfer and mass transfer. The effect of different parameters of cored wire injection to wire feeding speed were studied, such as different processing temperature of molten iron, different thickness of metallic sheath and different diameter of cored wire. The influence of processing temperature and wire feeding speed on the yield of alloy element was investigated. The effect of different parameters of cored wire injection to vermicular graphite rate and mechanical property of vermicular graphite cast iron was analyzed. Then, a mathematical model of one-step cored wire injection vermiculizing process and inoculation process was bulit, which could guide the industrial mass production of high quality vermicular graphite cast iron castings.RE alloy cored wire, Mg alloy cored wire and ferrosilicon alloy cored wire with the diameter of 10 mm were used for one-step cored wire injection vermiculizing process and inoculation process successively. In order to obtain high quality vermicular graphite cast iron castings, the residual Mg and RE content in molten iron should be controlled in the appropriate range for the formation of vermicular graphite. In one-step cored wire injection vermiculizing process and inoculation process, molten iron was firstly vermiculized by RE alloy cored wire and Mg alloy cored wire directly, respectively. Then, inoculation process was carried out by adding ferrosilicon alloy cored wire. The practical experiences and results show that when the residual Mg and RE content were precisely controlled in the range of 0.013%～0.017% and 0.019%～0.025%, respectively, high quality vermicular graphite cast iron castings without flake graphite and more than 80% vermicular graphite rate were obtained.In the paper, based on classical control theory, control algorithm of stepless frequency conversion control for the speed of driving motor in one-step cored wire injection vermiculizing process was optimized. Self-adaptive fuzzy and PID controller for one-step cored wire injection process was designed. The simulation model of the driving motor was established at Matlab/SimuLink environment. The traditional PID control system and self-adaptive fuzzy and PID control system were applied in driving motor of cored wire injection vermiculizing process equipment, respectively. It is can be verified through simulated test that compared with traditional PID control system, self-adaptive fuzzy and PID control system has the advantages of higher response rate, smaller overshoot and shorter adjusting time, and could realize ideal static performance and dynamic performance of one-step cored wire injection vermiculizing process control system. At last, industrial control computer, CPU module and I/O control module of Simens S7-300 PLC, high speed counter FM350-2 module and HMI touch panel were applied to PLC programme for control system of one-step cored wire injection vermiculizing and inoculation process, which could offer a hardware platform for the realization of self-adaptive fuzzy and PID control algorithm.