Research On Servo-pump Drive Control System For Electro-hydraulic Injection Molding Machine

Abstract:With the development of plastic industry, the injection molding machine develops gradually toward energy-saving、efficient and high accuracy direction. Traditional hydraulic injection molding machine has long service life, but it is energy-consuming and inefficient. The electric injection molding machine is driven by servo permanent magnetic synchronous motor(PMSM),which has high control precision, but it is expensive and the service life is short. Combined with the advantages of both, the electro-hydraulic injection molding machine has become the mainstream of development.The injection molding machine requires servo-pump to switch operation mode in Fill-to-Pack process.The pressure shocks or fluctuations caused by process of switch,are the main factors that affecting the quality of plastic products. Keeping smooth switching process is an important research topic for injection molding machine manufacturers and plastic products manufacturing enterprises at home and abroad. Therefore, studying the machine control and switch strategy to improve the performance of injection molding machine and product quality is of great significance and practical value.The paper analyses the composition of the injection molding machine and its working principle, as well as the control principle of permanent magnet synchronous motor in detail,using PMSM vector control algorithm to implement flow control of the injection molding machine. For the shortcomings of common Fill-to-Pack switch methods, the paper puts forward an approach of the pressure changing rate. When the servo-pump operates in the pressure loop,using fuzzy adaptive PID controller to adjust the system pressure,it makes pressure loop have strong robustness to the load of the hydraulic system.In addition, the paper proposes a software decoding method for resolver signal process.Finally,The paper develops the hardware and software of the system using DSP TMS320F2812as the core chip. Through the experiment,the result shows that the resolver signal process method is effective.The injection molding machine servo-pump system has fast speed response and strong anti-jamming ability. And the switch process is smooth. Pressure loop has a good performance.Above all,the drive control system can meet practical application requirements for injection molding machine. Figures(52), tables(9), references(70).