FILM STRETCHING INSTALLATION FOR PREVENTING SOILING DUE TO MELTING OF THE FILM AND METHOD FOR PREVENTING SUCH SOILING IN SUCH AN INSTALLATION

摘要

The invention relates to a film stretching installation (1) having a transverse stretching region (3) with treatment zones (2) for heating and/or stretching, through which a film to be stretched (4) can be guided and can be impinged and heated by a gaseous treatment fluid (7) that emerges from a plurality of nozzles (5) of respective nozzle regions (6). The film is stretchable in a direction transverse to the through-feed direction thereof (8) by heating the film (4) with the treatment fluid (7). According to the invention, a shielding device (9) is provided, which, on the basis of a signal corresponding to a damage to the installation, can be guided between the film (4) and the nozzles (5) for the covering and/or shielding of the impingement of the film (4) by means of the treatment fluid (7). The invention also relates to a method for preventing soiling in particular of the nozzle regions (6) for treatment fluid (7) of films (4) in film stretching installations (1), which occurs as a result of melting of the film (4). In this case, the nozzle regions (6) in the film stretching installation are covered during its standstill in such a manner that the films (4) are not subjected to treatment fluid (7) from nozzles of the nozzle regions (6) at least on their lower side (4a).