| 摘要 |
In connection with the unreeling of a paper or foil web from a supply reel, e.g. in a flowpacking machine, it is well known to move the web through an adjustment station for maintaining a constant tension of the web in the outer length thereof. Normally, this is achieved by the use of a synchronously driven unreeling roller partially entwined by the web and a system for adjusting the degree of entwining based on a current detection of the web tension. With the invention this is simplified by driving the unreeling roller with a peripheral speed noticeably higher than the web speed, whereby it is possible with a suitable angle of entwining to achieve both a relatively low web tension and an automatically self-adjusting, constant web tension. By virtue of the associated, rather low dynamic friction between the roller and the web, it is even possible to effectively control or maintain the lateral positioning of the web merely by the use of simple abutments for co-operation with the side edges of the web. |
