| China is the world's largest manufacturer of cemented carbide, but lots of such kinds of products are inferior. The products with high-tech and high value-added have very limited market share. Compared with same industry of abroad, there is also a big quality gap on the same products. How to improve the quality of cemented carbide product and increase technology progress is becoming the trend to develop high quality product in the cemented carbide industry in china. Vacuum sintering is a key process for sintered-carbide during production process, and furnace temperature control has a significant effect on the quality. Furnace temperature shall be strictly controlled by the technological heating curves of the product. Strict standard requirement on the tracking error and overshoot limitation is also a must.It is difficult to establish accurate mathematical model. The dynamic characteristics of vacuum furnace have the characteristics such as, non-linear, time variability, uncertainty, and long time delay and so on, and it is hard to resolve carbide sintering furnace temperature control problem by using traditional PID(Proportional-Integral-Derivative) control methods. This thesis puts forward a new method for furnace temperature which is controlled by incomplete derivative PID based on ACA (Ant Colony Algorithm). Basically, ant colony algorithm is a probabilistic search algorithm, and the main characteristics of ACA are strong robustness and very good distributed computation. It gains the optimal solution by updating the local pheromone and whole pheromone. The result of PID control depends entirely on its parameters setting, and this method will optimize PID parameters by using the optimizing solution of the Ant Colony Algorithm, meanwhile, by using OPC(OLE for Process Control) technology to achieve real-time data exchange between the upper computer and the PLC(Programmable Logic Controller) and the online optimization and remote monitoring.Practical operation results show that tracking errors of the temperature can meet the technological process requirements, and this temperature control system has been significantly improved than the original temperature control system. |
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