process and device for manufacturing a sleeve folding flat coil of polygonal cross-section

摘要

The process is for the manufacture of sleeves of straight polygonal section, particularly for use as a packing item and folding flat. A round tube is first formed by winding several thin layers of glued paper, plastic etc. on a fixed mandrel. The tube is then distorted into the polygonal shape, and during this operation and while it is still wet from the glue a continuous fold is pressed into it along each edge in the lengthwise direction. After the tube has been wound to its final wall thickness it is divided into separate sections. These are then fed forward separately and individually subjected at the same time to the distorting and folding operations.