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Open Blown technology
Compared to the traditional blown film making machinery and technology, the cutting and opening of the closed bubble is the most spectacular modification we have made. There were several reasons for opening the bubble: one of them is to further increase the cooling intensity by letting the warmed up air out of the bubble that detained the recooling of the film to room temperature. The next reason is, we wanted to process the film cut to 6 stripes on smaller winders. First we wanted to lead the film of a traditionally closed bubble to more winders, and there we got the idea of cutting the bubble before closing.
At the take-up level the upwarding bubble cylinder is cut into 6 identical segments with knives positioned in radial direction. On the take-up level 6 small take-up units can be found. Onto each of these units a film segment is lead wherefrom the stripes are lead to the detached winding units.
The caliber functions as a plug. It does not allow the air to break out of the bubble which therefore enables the production with open bubble. The new cooling-caliber unit can be used with the traditional technology as well, because every closed-bubble type machine that has a channel in its die can be installed with it. The advantages to be gained with our new technology are the precise diameter keeping and the good physical parameters of the evenly and quickly refrosted film. The production lines having the so-called pancake dies can also be supplied with the cooling-caliber unit improving their production speed and making their operation more economical.
The new cooling-caliber unit can be used for the production of HDPE films as well, where first the axial, then the radial orientation develops. The unit can be installed in both production phases, and furthermore, the external cooling can be replaced with internal cooling.