Design Of Plastic Extruding Machine Temperature Control System

Extruding machine is an important equipment of plastic extruding production and processing. At present, the most of plastic products are completed through plastic extrusion machine. In the extrusion process, the temperature of extruding machine has a direct impact on the performance and quality of products, so temperature control is good or bad is becoming a key factor in product quality.For extruding machine temperature control, the partition control method is commonly used, but there exists strong coupling between the temperature of two areas, and variability for a single area because of disruptions. Extruding production process has strict requirements of control accuracy and stability of the temperature. This paper takes cable outer casing production as the background, analyzes the characteristics of extruding machine temperature control, and designs the temperature control system architecture. In the structure, PROFIBUS is used to form a field control network, so that all parts of line are modular controlled, which is easy for maintenance and functional extensions. Chooses the reasonable control mode, divides the cylinder and head of extruding machine into several areas, for each area, uses two-stage controller to realize temperature control, which is flexible and versatile.Proposes a PID multi-loop decoupling control algorithm based on fuzzy control which combining intelligent control with conventional PID. This method adjusts the reference PID controller real-time according to the error of own loop and adjacent loop and using fuzzy control which imitates experience of experts or technical personnel to reasoning. Thus weakens or eliminates the effects of controlled object multivariable coupling. In addition, makes optimization for single loop PID control, uses PID setting value segment given method to reduce the system overshoot and shorten the adjustment time; uses integral separation to inhibit output saturation and reduce volatility, thereby eliminates the impact of large site and disturbance to the system. Compared with the conventional PID and general fuzzy PID control algorithm, the method is more robust anti-coupling, and more resilient.Based on the proposed temperature control method, combined with the feature of cable outer sheath production line, makes the hardware and software design of system. In terms of hardware, uses PROFIBUS to composed of control network for data transmission; takes the thermocouple temperature as a temperature sensor to complete the acquisition and strip heater and cooling fan control as the implementation to control heating power; uses IPC and PLC as control devices, where the IPC adopts intelligent control algorithm to complete calculations and sends the relevant parameters sent to PLC, PLC completes the field control based on PID algorithm. In terms of software, gives the control structure and the main control process of the IPC and PLC respectively; designs extruding machine temperature monitoring system, achieving human-computer interaction and the entire system monitoring, completing the relevant parameter settings and system data storage, real-time and historical data display and system alarm.Intelligent adaptive PID control algorithm is able to complete the control requirements and it is effective and feasible and superior to conventional PID control algorithm and other control algorithm without decoupling. The extruder temperature control system based on the algorithm uses open networking solution, which is easy for future maintenance and expansion, having strong flexibility and practicality.