February 27, 2023
Blow molding machine Operating principle
During the production process of blowing plastic film, the thickness of the thin film is a very critical indicator. Among them, the vertical thickness uniformity can be controlled by squeezing and traction speed stability. , And with the changes in production process parameters, in order to improve the thickness of the horizontal thickness of the film, the automatic horizontal thickness control system must be introduced. The commonly used control methods include the automatic mold (thermal expansion screw control) and the automatic wind ring. Principle and application.
The dual air inlet method is adopted in the automatic air rings structure. Among them, the air volume of the lower air outlet is kept constant. The upper winding mouth is divided into several airways. Each air duct is composed of wind rooms, valves, motors, etc. Degree to control the amount of air volume of each air duct.
During the control process, the thick -film thick signal was passed to the computer by the thick -meter -tested probe. The computer compared the thick signal with the current set average thickness. According to the thickness of the thickness and curve change trend, control the motor drive valve to move. When thin, the motor is moving, and the air port is small; on the contrary, the motor moves reverse, and the air outlet increases. By changing the air volume of each point on the weekly circle, the cooling speed of each point is adjusted, so that the film's horizontal thickness deviation is controlled in the range of the target. Essence
The automatic wind ring is an online real -time control system. The system is controlled by several motors distributed on the wind rings. The cooling air from the fan is assigned to each air duct after constant pressure of the wind rings, and the motor drive valve is used as the opening and closing movement to adjust the air outlet and air volume to change the cooling effect of the membrane at the formation of the mold. Therefore, the thickness of the film is controlled. From the perspective of the control process, the thickness of the thickness of the film cannot find a clear relationship with the amount of motor control. Different thickness films and different positions between the thickness of different positions and valves. It has a great impact on the adjacent points, and the adjustment is lagging, which makes it interrelated between different moments. For this highly non -linear, strong coupling, time -degeneration and uncertain system Establishing, even if it can be established, it is very complicated that it is difficult to solve, so that there is no practical value, and traditional control has a good control effect on the control model. Even powerless. Given this we chose a fuzzy control algorithm. At the same time, change the change of fuzzy quantification factor to better adapt to changes in system parameters.
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