| Being plastic processing and molding equipment, injection molding machine?s manufacturing will inevitably affect the final quality of the molding plastic products. Good control of the barrel temperature is essential to ensure satisfactory quality of the injection molding products. Domestic injection molding machine barrel temperature control mostly depends on PID control method, this system has good robustness, but low temperature control precision with large overshoot. This paper studies the strategy of barrel temperature control in injection molding which focuses on the temperature start-up control and steady-state control, then carries out it based on the ?HNC-8? CNC systems.This paper designs the barrel temperature control system of injection molding machine on both hardware and software, studies on the key hardware selection, accomplishes the software system and part of its implementation, and develops the main user interface using Qt.In the temperature start-up control study, an issue is put forward on how to shorten barrel heating time and ensure small temperature overshoot. Upon the time optimal control theory in nonlinear system, the shortest time problem is worked out. The temperature start-up control algorithm is proposed based on open loop test of barrel heating, and the rationality of this control method is verified by experimental results.In the temperature steady-state control study, this paper design a barrel temperature controller with the combination of fuzzy control and PID control, on the basis of steady-state temperature characteristics. Though traditional fuzzy PID controller improves the control accuracy, it?s hard to set up fuzzy rule base which is dependent on the types of plastic and structure of the cylinder. To solve this problem, this article uses a self-organizing algorithm to adjust fuzzy regulations online. Finally, experimental results demonstrated that this method improves the nozzle temperature overshoot and steady-state deviation. |
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