Process for detecting and controlling the position of the release line of a film on a last calender roll of a plastics film calender and device for carrying out this process

摘要

In the process for detecting and controlling the position of the release line of a film from a last calender roll of a plastics film calender, a divergent light beam is directed at an intermediate region between this last calender roll and the first take-off roll, which light beam is reflected from the intermediate region and impinges as a reflected, widened beam on a light receiver, the receiving surface of which is substantially smaller than the cross-section of the reflected beam. The relative velocity of the two rolls can be controlled by means of the signal recorded by the light receiver.