Internal bubble cooling

V. Sidiropoulos and J. Vlachopoulos, Numerical Study of Internal Bubble Cooling in Film Blowing, Int. Polym. Process., 16, 48-53, (2001). 

Fig. 3 Schematic of spiral mandrel blown film die operation (1) ring-shaped melt distribution (2) die body (3) spiral flow mandrel (4) sizing ring (5) spreader (6) film bubble (7) frost line (8) solidified film (9) bubble collapsing rollers (10) nip rollers (11) external bubble cooling air (12) internal bubble cooling air inlet (13) internal bubble cooling pipe and (14) heated internal bubble air return.

The properties of the film are determined by the blow-up ratio and the speed. The blow-up ratio is the ratio between the diameter of the final tube of film and that of the die. The internal air pressure that expands the tube into the bubble is typically supplied through a port into the mandrel, the interior part of the die. Once the process is running steadily, little air is usually lost, so make-up requirements are small. When internal bubble cooling is used, air is constantly being exchanged inside the bubble. 

IBC internal bubble cooling ILD indentation load deflection... 

Bubble Breathing occurs when the air volume inside the bubble increases and decreases periodically. This is primarily a problem with internal bubble cooling (IBC) systems, since there is an internal air exchange occurring continuously. Solutions generally focus on checking IBC valves, blowers, and sensors. 

Figure 5.40 Cooling methods for blown film lines (a) single-lip air ring, (b) dual-lip air ring, and (c) internal bubble cooling. ...

Fig. 4. Blown film process, quench air ring, and internal bubble cooling.

I moment of inertia IB isobutylene IBC internal bubble cooling IBM injection blow molding IBM International Business Machines IC Industrial Computing publication ICM injection-compression molding ID internal diameter lEC International Electrochemical Commission... 

In industrial practice, cooling of the blown film is enhanced from the outside by an annular air jet, which fiows from an air ring (see Fig. 9.20) attached very close to the die and/or the inside by a process called internal bubble cooling (IBC). Note that the air jet usually hits the film... 

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