Folding roll for a folding apparatus and methods for its production

Abstract

A folding roll distinguished by good shape and dimensional accuracy bears a frictional layer applied to the even surface of the folding roll, adjacent deeper areas being formed by application-free regions. The method of producing the folding roll includes the fitting of a mask to the folding roll, the mask having cutouts with the form of frictional areas to be applied. This is followed by the application of the frictional layer by means of thermal spray-coating and, following that, the removal of the mask.

What is claimed is:  
     
         1 . A folding roll for a folding apparatus, said folding roll comprising: 
 at least one cylindrical surface having at least one frictional area to which frictional material has been applied by thermal spray coating, said at least one frictional area being bounded by deeper areas to which no friction material has been applied.    
     
     
         2 . A folding roll as in  claim 1  wherein said at least one frictional area comprises a plurality of four-corned frictional areas.  
     
     
         3 . A folding roll as in  claim 1  wherein said at least one frictional area comprises a strip of frictional material running spirally around said cylindrical surface.  
     
     
         4 . A folding roll as in  claim 1  wherein said at least one cylindrical surface comprises a plurality of cylindrical surfaces separated by circumferential channels for tape lines, each said circumferential channel having a circumferential surface provided with at least one frictional area to which frictional material has been applied by thermal spray coating.  
     
     
         5 . A folding roll as in  claim 1  wherein said frictional material has a depth of about 0.3 mm on said frictional areas.  
     
     
         6 . A folding roll as in  claim 2  wherein said folding roll comprises part of a third longitudinal folding apparatus.  
     
     
         7 . A folding roll as in  claim 3  wherein said folding roll comprises part of a folding former.  
     
     
         8 . A method of producing a folding roll for a folding apparatus, the method comprising: 
 fitting a mask to at least one cylindrical surface, said mask having cutouts shaped and arranged to correspond to the shape and arrangement of desired frictional areas on said at least one cylindrical surface;    applying a frictional material by means of thermal spray-coating to said mask and said at least one cylindrical surface via said cutouts; and    removing said mask.    
     
     
         9 . A method as in  claim 8  wherein said mask is provided with longitudinal edges, said mask being fitted to said at least one cylindrical surface so that said longitudinal edges form a butt joint.  
     
     
         10 . A method of producing a folding roll for a folding apparatus, the method comprising: 
 winding a strip-like mask around a cylindrical surface spirally to form turns separated by a gap corresponding to a frictional area extending spirally around said cylindrical surface;    applying a frictional material by means of thermal spray-coating to said mask and said at least one cylindrical surface via said gap; and    removing said mask.