Folding blade for a blown film line as well as blown film line with such a folding blade

Abstract

The invention relates to a folding blade for a blown film line, as well as to a blown film line equipped therewith. Folding blades are used for laterally folding in a film bubble running to the take-off pinch rolls. If they engage deeply into the film bubble, they are provided with a fin on the rear side, and referred to as deep folding blades. The invention proposes that the rear side of a folding blade be equipped with a fin, which exhibits a collapsible element with an adjustment device. The volume of the fin can thereby be varied. In particular, the fin can be laid flat against the rear side of the folding blade.

1 . A folding blade for a blown film line, with a folding surface for folding in a film bubble running alongside, as well as with a fin protruding toward the back from the folding surface for preventing folding flanks projecting around the folding surface from coming into contact with each other, wherein the fin exhibits a collapsible element with an adjustment device. 
     
     
         2 . The folding blade according to  claim 1 , wherein the collapsing element exhibits a bellows and/or the adjustment device is designed as a volume adjustment device. 
     
     
         3 . The folding blade according to  claim 1 , wherein the adjustment device exhibits a connection for a fluid guide. 
     
     
         4 . The folding blade according to  claim 1 , wherein the fin exhibits a fixed element. 
     
     
         5 . The folding blade according to  claim 1 , wherein the fin exhibits a guide for the collapsing element, preferably located on a fixed element of the fin. 
     
     
         6 . The folding blade according to  claim 1 , wherein the collapsible element exhibits a swiveling edge. 
     
     
         7 . A blown film line with a folding blade according to  claim 1 , wherein the folding blade is arranged between a bubble expansion zone and take-off pinch rolls, and the fin is aligned facing away from a vertical axis of a film bubble. 
     
     
         8 . The blown film line according to  claim 7 , wherein a connection is used to hook up the adjustment device to an energy source of the blown film line, in particular to a pump. 
     
     
         9 . The blown film line according to  claim 7 , wherein the collapsible element is situated at the height of a swing bearing or another frame part of the blown film line. 
     
     
         10 . The blown film line according to  claim 7 , wherein displacing the collapsible element provides two or three or four different folding operation modes to choose from, specifically:
 a. A deep folding operation mode, in which the folding surface and fin are arranged so as to engage into the ascending film bubble, and the fin protects the film bubble folded in from the folding surface against its folding flanks coming into contact with each other during operation, and/or   b. A first folding operation mode, in which the collapsible element is present in the collapsed state, and the folding flanks of the film web folded in from the folding surface still do not come into contact with each other, and/or   c. A second folding operation mode, in which the collapsible element is present in the collapsed state, and does not contact the folding flanks of the film web folded in from the folding surface, and/or   d. A non-folding operation mode, in which the folding surface of the folding blade and the fin are varyingly positioned relative to the folding operation types, so that they do not engage into the ascending film bubble, wherein the fin is preferably collapsed, so that the folding surface generates no folding flanks during operation, and the blown film line flattens out the film bubble without folding in.