How many customized control methods are there for the hydraulic system of injection molding machines?

How many customized control methods are there for the hydraulic system of an injection molding machine? As a plastic molding processing and production equipment, the injection molding machine is gradually developing towards precision, lightweight and miniaturization to meet the market's requirements for injection molded products. Traditional control systems have gradually failed to meet actual production needs. In order to achieve multi-level and micro-control of process parameters in the process of precision product molding, it is also necessary to study the accuracy and stability of the injection molding machine control system, and strive to improve the operation production efficiency while ensuring the quality of injection molded products.

The two main parameters of the customized hydraulic system of the injection molding machine, pressure and flow, have strong coupling and nonlinear characteristics. Based on the analysis of the characteristics of the injection molding process, in order to better adapt to the production parameters of different injection molding products, the injection pressure and injection speed must be accurately controlled to avoid premature or delayed injection shutdown. There are quality problems such as full material or polymer overflow. Based on this, it can be judged that it cannot be adjusted by overshoot. It is necessary to select a scientific and feasible control strategy for the characteristics of the hydraulic system of the injection molding machine that does not allow overshoot to achieve precision control requirements.

For the traditional PID algorithm, its control effect on the pressure and flow parameters of the injection molding machine is not obvious. In practice, it is generally used in combination with fuzzy intelligent algorithm and genetic algorithm, especially BP neural network has strong nonlinear mapping ability and flexible network structure, which has good optimization effect on PID control algorithm, but it also has the defects of slow convergence speed and easy to fall into local minimum. For the design optimization of precision injection molding machine hydraulic control system, particle swarm algorithm can be selected, combined with BP neural network algorithm, and its high precision can be used to realize online adjustment of PID parameters. And fast convergence characteristics. After optimized design, the hydraulic control system of injection molding machine mainly consists of PID controller, injection molding machine hydraulic oil pump, servo motor and pressure/flow sensor on the oil pump, forming a closed-loop system, which can meet the high precision and fast response requirements of the whole system.

There are two ways to customize the hydraulic system of injection molding machine

1. Pressure control

As one of the important parameters affecting the performance and specifications of injection molding machine, pressure needs to provide corresponding hydraulic pressure for each action in the face of different injection molding processes. Therefore, when designing the control system, attention should be paid to the analysis of pressure control state. Determine the oil circuit fluid

Pressure is the control object. For the quantitative pump hydraulic system driven by AC servo motor, a pressure transmitter is installed in the main oil circuit to complete the detection of system hydraulic pressure. The pressure transmitter outputs a 0-10V voltage signal. The CNC system of the injection molding machine needs to transmit the injection molding process pressure command processed by the servo controller to the servo motor starter. The pressure transmitter detects whether the hydraulic pressure reaches the set pressure value, and then the servo control adjusts the pressure control state. Then, the detected pressure value is compared with the set pressure value, the speed and torque of the servo motor are calculated and controlled, and the hydraulic pump is driven to provide hydraulic pressure for the injection molding machine.

2. Flow control

Flow control is to determine the flow of each action cylinder as the object, to ensure that each mechanism driven by the cylinder can move quickly and achieve a high production efficiency. After the CNC system of a large injection molding machine sends a flow command signal to the AC servo motor driver, it drives the AC servo motor to run and drives the quantitative hydraulic pump to run at high speed. The volumetric efficiency of the quantitative hydraulic pump is determined as a fixed value, and it is confirmed that the number of motor revolutions is linearly related to the hydraulic flow in the oil circuit, so that the purpose of controlling the hydraulic flow of the injection molding machine can be achieved by controlling the speed of the AC servo motor. Among them, the relationship between the servo motor speed and the output flow of the metering pump is: Q=CnV, Q represents the output flow of the metering pump; n represents the speed of the AC servo motor; C represents the volumetric efficiency of the metering pump; V represents the rated displacement of the oil pump.