Simulation And Experimental Research On Temperature Control Of Multi-channel Injection Molding Machine Based On EtherCAT

Injection molding machine is an important part of the plastic machinery industry and has an important impact on the national economy.my country’s injection molding machines widely use centralized control in intelligent control,injection molding accuracy,industrial integration,etc.,which have defects such as poor system reliability,poor software and hardware expansion flexibility,and slow data transmission rate.Compared with foreign injection molding machines,they are still relatively large.insufficient.In this paper,the distributed barrel temperature control system of injection molding machine is designed,and the barrel temperature control scheme is determined from two aspects: reducing the heating time and improving the temperature control accuracy.The details are as follows:(1)Analyze the requirements of the temperature control system.Complete Beckhoff CX2020 embedded controller,slave interface module,temperature acquisition module,PWM output module,etc.The characteristics of the distributed control bus are analyzed,and the EtherCAT field bus is selected as the communication protocol and ring network topology of the temperature control system.The EtherCAT distributed clock is designed to maintain high synchronization between TwinCAT,the system master and each slave.(2)Design the single-stage barrel heating experiment,build the mathematical model of the temperature control system,and use the two-point method to adjust the parameters of the mathematical model.Analyze the factors that generate and dissipate the heat energy of the injection molding machine barrel,and the temperature control characteristics,and prepare for the algorithm design and simulation analysis of temperature control.(3)Design the optimal experiment of the barrel heating time based on the Pontryagin minimum theory,analyze the relationship between the barrel heating time and the system constraints,obtain the formula about the power switching of the barrel heater,and determine the control of the shortest heating time of the injection molding machine barrel Program.Aiming at the disadvantage that the basic universe of traditional fuzzy controllers cannot be changed,fuzzy controllers with variable design factors are designed to adapt to system changes.(4)The software part of the temperature control system is designed,through the mixed programming of Matlab and TwinCAT3,Matlab performs algorithm calculation,and TwinCAT3 performs multi-channel real-time processing.Design PID,fuzzy PID,and fuzzy PID algorithm based on Smith’s forward feedback,and carry out simulation comparison and stability analysis in Matlab/Simulink.Based on the nine-point control method,an improved Smith feedforward compensator is designed to improve the temperature control accuracy.The fuzzy decoupling control based on temperature difference is designed to reduce the thermal coupling inside the barrel.(5)Design the interface in TwinCAT3 PLC HML,the staff can check the status of the temperature control system.Finally,the results show that the overshoot is within 1%,and the accuracy is within ±1°C.