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Extrusion Blow Molding Machine: its advantages and how it works.
- Apr 19, 2018 -

After the liquid plastic is sprayed out, the Machine is used to Blow out the wind, and the plastic body is blown into the mold cavity of a certain shape to make the product. This Machine is called the Blow Molding Machine.The plastic is melted and quantified in the screw extruder, and then it is formed through the mouth mold, then the wind ring is cooled, and then the tractor is pulled at a certain speed, and the winding machine turns it into a coil.

Advantages

1. The screw center shaft and cylinder are made of 38CrMoAlA chromium, molybdenum and aluminum alloy through nitrogen treatment, and have the advantages of high thickness, corrosion resistance and wear resistance.

2. The die head is plated with chromium, and the screw spindle structure makes the unloading more equal and smooth, and the blowing film is finished better.The complex blowing machine structure makes the output gas more uniform.The lifting unit adopts the square frame platform structure, and the height of the frame can be adjusted automatically according to different technical requirements.

3. The unloading equipment is used to rotate the equipment and the center rotating equipment, and adjust the film smoothness with torque motor to facilitate operation.


How it works.A simple overview.

In the process of blown film production, film thickness uniformity is a key indicator of the vertical thickness uniformity can be controlled through extrusion and drawing speed stability, and the lateral thickness uniformity of film generally in accordance with the resistance in die precision manufacturing, and changes along with the production process parameters, in order to improve the lateral film thickness uniformity, to introduce automatic transverse thickness control system, the common control methods include automatic die head and automatic wind ring, it mainly introduces the principle and application of automatic wind ring.

The basic principle

Automatic wind ring structure adopts double draught method, including the tuyere air volume constant, the tuyere on the circumference of a circle is divided into several air duct, each air duct is composed of air chamber, valve, motor, valve adjusting air duct is driven by a motor, control the size of each duct air volume.Control in the process, the film thickness thickness sensor detected signals to the computer, the computer signal is compared with the current set average thickness, thickness according to the amount of thickness deviation and curve tendency of operation, control motor drive valve movement, when film slants thin, motor forward motion, tuyere down;On the contrary, the motor is moved backward and the tuyere is enlarged. By changing the air volume of each point on the circumference of the wind ring, and adjusting the cooling speed of each point, the thin film transverse thickness deviation is controlled in the target range.

Control scheme

The automatic wind ring is an on-line real-time control system, which is controlled by several motors distributed on the wind ring.By fan cooling airflow from the wind ring wind chamber after constant pressure distribution on each air duct, valve for opening and closing motion driven by a motor to adjust tuyere and the size of the air flow and change the die head discharging membrane billet cooling effect, so as to control the film thickness, from the control process, the membrane thickness change and the motor control quantity can not find a clear relationship between change and the thickness of different film thickness and the valve position control process nonlinear irregular change, between each adjustment are of great influence on adjacent point when a valve, and adjust the lag, and associated with each other, between the different time for this kind of highly nonlinear, strong coupling, time-varying uncertainty and control systems, and almost impossible to establish the precise mathematical model, even if is to establish mathematical model, it is also very complicated, difficult to solve, so that no practical value, and traditional control on the control model control effect is better, for the highly nonlinear, uncertain, complex feedback control effect is very poor and powerless.In view of this, we choose fuzzy control algorithm.At the same time, the change of fuzzy quantization factor is adopted to better adapt to the change of system parameters.

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