Control plan design and basic principles of plastic blow molding machines

2019-04-30 17:21:53

Mainly from the control plan and basic principles of the blow molding machine to analyze.

Control plan design
Automatic blow molding machine automatic air ring is an online real-time control system. The system is controlled by several motors distributed on the wind ring. The cooling airflow sent by the fan is distributed to each air channel through the constant pressure of the air ring air chamber, and the motor drives the valve to open and close to adjust the size of the air outlet and the air volume, and the cooling effect of the film blank at the die discharge is changed. Then control the thickness of the film. From the control process, there is no clear connection between the film thickness modification and the motor control amount. The thickness of the film and the valve are not the same. The thickness of the change and the control amount are nonlinear and irregular. A valve has a great influence on adjacent points, and the adjustment has hysteresis, so that different times are related to each other. For this highly nonlinear, strong coupling, time-varying and non-deterministic system, the precise mathematics The model can't be established. Even if the mathematical model can be built, it is very messy and difficult to solve, which has no practical value. However, the traditional control has better control effect than the judgment control model, but for highly nonlinear, non-judgment, messy response information control. The effect is very poor and even powerless. In view of this we chose the confusing control algorithm. It is very good to use the modified fuzzy quantization factor method to change the system parameters.

Fundamental:
The double air outlet method is adopted in the automatic air ring planning. The air volume in the inferior position is kept stable. The upper air outlet is divided into several air ducts. Each air duct is composed of a wind chamber, a valve and a motor. The motor is driven to adjust the air duct opening. Degree, control the air volume of each air duct.

During the control process, the film thickness signal is transmitted to the computer by the thickness measuring probe, and the computer compares the thickness signal with the uniform thickness at that time. The blow molding machine calculates the thickness according to the thickness error and the curve changing trend, and controls the motor to drive the valve to move. When the film is thick, the motor moves forward and the air outlet is closed; on the contrary, the motor moves in the opposite direction and the air outlet increases. By changing the air volume at each point on the circumference of the air ring, the cooling speed of each point is adjusted, so that the lateral thickness error of the film is controlled. The scale of the policy.