Classification of air ring
According to the different structure and function, the air ring is generally divided into single tuyere air ring, double tuyere air ring and inner cooling air ring in the membrane bubble inner cooling system (IBC).
Single tuyere air ring has simple structure and low price, and is widely used in medium and low-grade film blowing units.
There are two separate air outlets at the top and bottom of the double air outlet air ring. The jet ring is added at the upper air outlet, and the cooling effect is significantly improved than that of the single air outlet. It is generally configured on medium and high-end models.
The inner cooling air ring (IBC) is placed inside the membrane bubble to cool its inner surface by using the hot air floating principle. It needs to be used with the inner cooling die. The inner cooling air loop, together with the on-line thickness measuring device and the computer information feedback control form the "membrane bubble inner cooling system (IBC)".
Function of air ring
The function of the air ring is to cool the film bubbles extruded and blown from the die, and the cooling medium is air. At the same time, the air flow also plays a role in supporting the membrane bubble. High efficiency air ring can significantly improve the output of the unit. The film bubble formed by the film blowing machine is in a molten state when it leaves the touch head, and needs to be cooled and shaped quickly. Otherwise, the film bubble will fall or adhere during winding, which will affect normal production. In addition, the rapid cooling of the film bubble has greatly improved the mechanical and optical properties of the film products.
Since the cross section of the membrane bubble is circular, the cooling air flow it needs must be a 360 degree annular air flow. In addition, because the strength of the film bubble is low when it is not cooled, the air flow and the film bubble must have a certain angle, and the direction of the air flow cannot be perpendicular to the longitudinal direction of the film bubble, otherwise the film bubble will shake and deform due to excessive force and affect the molding. The wind ring is created to meet this demand. The high-speed unidirectional air flow blown by the fan turns into annular air flow through the guide vanes and labyrinth air walls in the air ring body, and is blown to the membrane bubble through the air outlets with appropriate angles. The high-temperature membrane bubble contacts with the cooling air, and a large amount of heat on the membrane bubble is transferred to the air and taken away, thereby cooling the membrane bubble.