Method of and apparatus for embossing and controlling the web tension in a continuous, moving web.

摘要

Apparatus for embossing a thermoplastic web 12 comprises radiant heaters 18, 44 for heating both back and front of a hanging portion of the web from room temperature to a temperature suitable for embossing to take place, exclusively by radiant heat. Tension in the web is controlled by causing a portion 48 thereof between a feed-in drive 46 and the embosser 20 to sag, sensing the depth of sag by having the sagging portion intersect the line of sight between a photo-electric emitter 72 and a photo-electric sensor 74, and controlling the speed of the embosser in relation to the speed of the feed-in drive in accordance with the sensed depth of sag. Downstream of the embosser the web is reheated and thereafter cooled to room temperature.