Film blowing machine temperature indicators and control

Film blowing machine temperature indicators and control
According to the theory of molten plastic, blown film extruder screw were divided into three: the feed zone, melting, homogenizing segment. The end of the feeding section, into the melting begins, according to theoretical melting, its temperature should be viscous flow temperature.
Blown film resin temperature of viscous flow, respectively PP :164-175 degrees Celsius, PE :105-135 degrees Celsius, PA :195-210 degrees Celsius.

In the feed zone entrance, hoping the temperature low, to prevent the resin viscous flow blocked the inlet, addition, resin in the feed zone continued compression, the air backwards from the feeding port to discharge. Depending on the device structure is different, though not for heating feeding ports, but the heat transfer through the barrel, feed port temperature of about 50-90 degrees. In this way, feed section temperature is determined. Entrance to 50-90 degrees, melting point or the end of the viscous flow is equal to the temperature, the temperature can be set on a segment geometric linear warming. Melting begins, the temperature reaches the temperature to melt viscous flow, the crystalline resin, viscous flow temperature equal to the melting temperature. And then continue to compress and increase the melting layer, the temperature rising on the need to make resin molecular chain length ranging from the different thermal motion energy of the molten polymer has both, so the melting temperature of the end of the establishment, you can set in this section
on other parts of the linear warming.

In all of the segments, mainly re-melt homogenization and quantitative output of the melt temperature at constant pressure, the section maintains a constant temperature, or melting end temperature is slightly higher (2-5 degrees).

For blown film, the temperature required by the lower segment on things, but it is not lower than the temperature of viscous flow, easy to put film and blown film normal. When the melt from the die exit out to have a certain viscosity, and will not rupture, collapse film phenomenon.
In general, it is lower than both the end of section 10-30 degrees, all of the segments from the mouth to feel the temperature can be regarded as arithmetic temperature drop.

For the extrusion temperature control points are:

Different kinds of resin, blown film processes are at different temperatures;

The same kinds of resin, different models and melt index, blown film process at different temperatures, the mobility index of large, low temperature.

The same kinds of resin, blown films of different thickness, process temperature is different, processing thick films, a number of high temperature process, the temperature of the mouth can touch the high point, help to reduce viscosity and improve productivity.
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