Development Of Temperature Control System For Injection Molding Machine Based On Water-cooled Electromagnetic Induction Heating

The traditional injection molding machine adopts resistance heating method,but the thermal efficiency of the resistance heating mode is low,only for the heating power of 30%?40%.Electromagnetic induction heating with its rapid temperature rise,high thermal efficiency,long life,good working environment and so on,since the 90s of last century in the injection molding machine industry can be widely used.However,the electromagneticinduction heating of the injection molding machine has the advantages of low temperature,low temperature control precision and long adjustment time.To solve this problem,in 2013,Beijing three Technology Co.,Ltd developed a water-cooled electromagnetic induction heating device,which has the characteristics of rapid cooling,accurate temperature control and adjustment time is short and so on.Our research group also began work on a water-cooled electromagnetic induction heating device in the same period,completed the study on the mechanism of injection molding machine of water-cooled electromagnetic induction heating device and heating device is developed,the temperature field of cylinder of electromagnetic heating simulation analysis and structure optimization.However,the temperature control system of injection molding machine based on water-cooled electromagnetic heating has not yet been realized,it is necessary to solve the problem that the water-cooled electromagnetic heating device is used in the injection molding machine and realize the optimal control of the temperature.In this paper,based on the analysis of the principle of the injection molding machine,and considering the temperature control technology of the injection molding machine,the overall scheme of the temperature control system of the water injection molding machine is proposed.Then,the mathematical model of electromagnetic induction heating device is established by parameter identification method,and the mathematical model is established to verify the correctness of the established mathematical model.Because the cylinder temperature of the injection molding machine is a strong coupling,large time delay,nonlinear time-varying system,and the thermal inertia of the injection molding machine is larger,which will make it difficult to achieve accurate control of the heating temperature.Based on this,a control strategy combining Smith predictive control with Linear Quadratic Optimal of PID parameters optimization is proposed,thus,the electromagnetic induction heating temperature of water cooling injection molding machine is controlled.The simulation results show that the control algorithm is applied to the temperature control system of water cooling injection molding machine,compared with the independent Smith predictive control,the adjustment time of the system is reduced by 42.1%,the overshoot is increased by 40.0%,and the steady state error is reduced by about 20.0%,compared with the traditional PID control algorithm,shorten the adjustment time of system 54.2%,the overshoot is reduced by 44.7%,the steady-state error is reduced by 50.0%,which verified the superiority of the proposed control algorithm.The design and experimental verification of the electromagnetic heating temperature control device of water cooling injection molding machine.According to the functional requirements of the temperature control system,the hardware and software design of the temperature control system of the water-cooled electromagnetic injection molding machine is completed.The experiments show that in the absence of heat sink,the Smith predictive control with Linear Quadratic Optimal is proposed,compared with the independent Smith predictive control,the adjustment time of the system is reduced by 18.7%,the overshoot is increased by 4.7%,and the steady state error is reduced by about 16.0%,compared with the traditional PID control algorithm,the adjustment time of the system is reduced by 19.7%,the overshoot is reduced by 35.9%,the steady-state error is reduced by 45.6%,which verified the superiority of the proposed control algorithm by experiment.And the control algorithm is applied to the temperature control system with or without heat sink,compared with no heat sink,the system adjustment time is reduced by 29.5%,the overshoot is reduced by a factor of 41.7%,and the steady state error is reduced by about 4.4%,for the same control algorithm,the control effect of the electromagnetic heating temperature control system is better after adding the heat sink.