Study On Key Technique Of High-Performance For Plastic Injection Molding Machine

The 21st century is a technological century, with the development of material technology, servo motor performance has been improved for injection molding machines high-speed, high-precision. The advance control technology for the further development and for the implementation of motor and pump join moulding machine driven system servo control provides the theoretical basis. The development of microcontroller, especially the development of chip technology, and the appearance of specialties DSP, has made the implementation of control algorithms possible.Energy-saving,high-speed,high-precision, low-noise is high-performance injection machine control system direction of development. However, high speed and high-precision is often contradictory against low noise. Control method optimization is meaningful in solving the energy-saving and high-speed, high-precision. It is necessary for injection molding machine control methods to be studied. Injection molding machines energy-saving hydraulic systems, from flow and pressure in the proportion of dual control in the past towards load sensitive adaptive control, then frequency converter speed control, servo control and servo close control. Advanced energy-saving power-driven system is very necessary in high-performance injection molding machines.Focusing on the problems above, the first this thesis taking the advantages of the fuzzy prodictive control theory, analyzes the speed controller of induction motor for the injection molding machine; Secondly, using the internal model control methods, the author deeply researched the current regulator of Permanent magnet synchronous motor; Thirdly, fuzzy control is used for motor and variables pump co-ordination control; Fourthly, to the conflicts of high-speed, and high-precision against low noise, the different joint ways of the motor and variable pump is studied; Finally energy-saving principles of servo motors variable pump-driven system for the injection molding machine are studied; The experiment has been done to compare it with valve-control systems.The main points of this papers are as follows:1)A speed controller is designed for induction motor. In the contol of induction motor, great errors will be produced in speed control due to the parameters of the resistance and reactance. Based on the model of induction motor, a fuzzy predictive control method for the nonlinear discrete systems is presented by introducing fuzzy logic system into predictive control strategy, a high performance speed controller is designed using fuzzy predictive control method.2) Based on the conventional theory of rotor oriented vector control for permanent magnet synchronous machine, the internal mode control approach is applied to the current regulation of indirect rotor flux oriented control of permanent magnet synchronous machine. In the vector contol of permanent magnet synchronous machine, great errors will be produced in current control of the axis of d and q due to the parameters of the resistance and reactance in a wider speed range. The design methodology of current regulator is presented and its dynamic and robust characteristics is analyzed using matrix singular values. Finally, the simulating and experimental results indicate that the system utilizing internal mode control current regulator has better tracking performance and higher steady precision, and improves the motor control effect, it also verifies the good performance of the IMC (internal model current control) in the indirect rotor flux oriented control of permanent magnet synchronous machine, especially less dependence to the motor parameters on the wide range of speed.3) Based on the fuzzy control theory, it is proposed that fuzzy control method is used in servo motor and variables pump co-ordination control. The problem of low-speed features, slow dynamic response, and precision being not easily assured are solved when variable frequency speed-control of the injection molding machine. The shortage of speed fluctuations is solved by fuzzy internal-model-co-ordinating control.4) To the conflicts between high-speed, high-precision and low-noise, the different joint ways of the motor and variable pump are researched. The result shows the coupling has a significant impact on servo motor pump system's response and noise.5) Energy-saving principle for the servo motor with variable pump system is studied. Based on them, comparison between servo motor with variable pump system and proportional valve system is done though experiment.