| As a basic material for the development of modern society and economy,plastic profiles are mostly processed by plastic extruders.In the production process of plastic profiles,the temperature control accuracy of the extruder has a direct and obvious influence on the plasticizing and mixing effects of the raw materials.Therefore,the development of a high-precision,fast-response extruder barrel temperature control system is of great significance to the plastic machinery industry.This subject comes from a certain Dalian Plastic Building Material Co.,Ltd.-a research project of high-efficiency plastic profile production technology and special equipment.This project takes the plastic extruder barrel temperature control system as the core research content.Based on the analysis of the system performance indicators,it focuses on the research of the extruder temperature control algorithm.At the same time,the hardware and software of the control system are designed,and the ultimate goal is to realize the application of the control algorithm on the extruder to improve the control accuracy of the barrel temperature and the stability of the system.Firstly,the process flow and working principle of the plastic extruder are analyzed,and the overall scheme of the temperature control system of the extruder is designed.The step response curve identification method is used to obtain the system model parameters,and the mathematical model of the barrel temperature control system is established.Using MATLAB / Simulink to simulate the conventional PID control method and fuzzy PID control strategy,it is difficult to set the conventional PID control parameters,the overshoot is too large,the adjustment time is long,and the fuzzy PID control has poor anti-interference ability.This paper uses the control strategy of combining BP neural network and traditional PID to design and build a 3-5-3 structure BP neural network PID controller.It proposes the introduction of inertial terms,momentum terms,and improved learning rate strategies to achieve the proportion of PID,The adjustment function of three parameters of integral and derivative.Under the MATLAB / Simulink environment,a new simulation model of the barrel temperature control system was built,and the system simulation experiment was analyzed.The simulation results show that the PID controller based on the BP neural network has better temperature control effect and anti-interference ability.Then the hardware and software of the temperature control system of the extruder are designed.The hardware part analyzes the overall configuration of the PLC and expansion modules in detail and performs hardware configuration.The main equipment selection and circuit design of the temperature sensor,barrel heater,cooling device and other control systems of the control system;the software part introduces the program structure of the control system,Use STEP7 programming software to write the main program of the temperature control system and realize the BP-PID control algorithm.At the same time,according to the design principles and user requirements,develop the Win CC monitoring interface of the extruder temperature control system to achieve human-computer interaction and online monitoring of the entire control system,and complete the setting and modification of real-time temperature parameters,storage of system data,and historical data.Display,alarm information display and query functions.Finally,the temperature control system of the designed extruder was tested and evaluated.Experimental data verifies the rationality of the control scheme design in this paper,improves the accuracy of barrel temperature control,and has better self-adaptability and stability. |
