Analysis on the importance of vacuum sintering furnace in powder metallurgy

Vacuum sintering furnace is in the vacuum, in the inert gas filled protection state, the principle of heating body heating, so that the material box to maintain uniform temperature, through thermal radiation conduction sintering, and through the temperature intelligent control system to achieve automatic temperature control.

Sintering is an important process in the process of powder metallurgy, and its temperature control determines the quality of products. The traditional temperature control system mostly adopts manual control, temperature meter combined with relay type control or PID continuous control. With the continuous progress of science and technology, the intelligent technology of vacuum furnace powder sintering rotary kiln has been applied to the control of sintering temperature. Although there are many kinds of intelligent temperature control system, they all have certain limitations, and can not realize the effective control of temperature in the complex process of powder metallurgy sintering, the research of intelligent temperature control system needs to be further.

Vacuum sintering furnace of powder metallurgy is a time-varying, large hysteretic and nonlinear heating system. Due to the complexity of its physical and chemical mechanism, it is difficult to obtain an accurate mathematical model. When the parameters change greatly and the control accuracy requirements are high, the general PID control effect is difficult to be satisfactory. Fuzzy control does not need the system to give an accurate mathematical model, according to the actual experience of the control rules, make a control decision table, the system according to the decision table control, especially suitable for sintering furnace such as complex industrial production objects. The main factors affecting the quality of products in the sintering process are sintering temperature and sintering time, especially the temperature requirements are very harsh, the temperature difference is generally not allowed to exceed the given value of ±3℃~5℃, so it needs to be strictly controlled.

Aiming at the characteristics of time change, large delay and nonlinear of vacuum sintering furnace of powder metallurgy, PID control is not ideal, so fuzzy control algorithm is chosen. The simulation model of PID control and fuzzy control is established and compared. The results show that the response speed of the system is very fast after adopting fuzzy control, the time to reach the steady state is only 3.2s, there is no overshoot, the steady state error is 1.2℃, and the steady state precision is very high. The simulation output of the system is close to the given input waveform, the system adjustment time is short, quickly enters the stable state, and the oscillation is very small. The fuzzy control is superior to the traditional PID control and can meet the temperature control requirements of vacuum sintering furnace of powder metallurgy.

The vacuum sintering furnace of powder metallurgy has the characteristics of nonlinear, large lag, and its complexity increases the difficulty of temperature control in the sintering process. In the actual vacuum sintering furnace temperature control system, due to its own limitations, it is impossible to achieve accurate temperature control, which also directly affects the quality of products. The application of intelligent technology makes the establishment of intelligent temperature control system. The intelligent temperature control system has the advantages of stable operation, high temperature control precision and strong adaptability. It has great application value and development space in powder metallurgy vacuum sintering furnace.