Bruckner Formtec GmbH of Siegsdorf said its automatically adjustable JuBo roll is the first roll in a three-roll stack for polishing thin PET film and sheet.
The patented roll is especially good for wide roll stack extrusion lines producing thin film and sheet.
According to Bruckner, making plastic film requires high line pressure for polishing, which results in roller deflection. High productivity also demands wide film, resulting in even higher deflection. The result is an uneven thickness cross profile of the film.
Convex rolls are often used to compensate for deflection, but they can only cope with one particular setup. Bruckner lines require adjustable crowning because they are highly flexible, used for many applications.
JuBo is not a mechanical system. Instead, it is based on thermal expansion and the incompressibility of oil. An oil-filled cavity is placed underneath the cooling spirals. During operation, the cavity reaches the temperature level applied to the cooling water of the roller. That builds up pressure - creating a symmetrical crowning deformation of the roller's outer shell.
The JuBo crowning polishing roller is designed for use on Bruckner lines.
In other news, the company introduced PET cast film technology with electrostatic pinning for film lay-on. This method no longer polishes the film between two rollers but instead casts it onto a chill roll.
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