Buckle folding unit and sheet-fed folding machine including the buckle folding unit

Abstract

A buckle folding unit for sheets includes a buckle plate, three rollers that form a transport roller pair and a folding roller pair, and a blown-air nozzle for guiding the sheets. The at least one blown-air nozzle emits a blown-air jet in a direction radial to a common roller of the transport roller pair and the folding roller pair. The air jet places the sheet against the surface of the common roller and guides it into a nip of the folding roller pair in a defined way, advantageously resulting in an improved quality of the fold. A sheet-fed folding machine including a buckle folding unit is also provided.

1 . A buckle folding unit for sheet-shaped elements, the buckle folding unit comprising:
 a buckle plate;   three rollers forming a transport roller pair for feeding the sheet-shaped elements and a folding roller pair for folding the sheet-shaped elements, one of said three rollers being a common roller of said transport roller pair and said folding roller pair; and   at least one blown-air nozzle for guiding the sheet-shaped elements, said at least one blown-air nozzle delivering an air jet oriented in a radial direction relative to said common roller.   
     
     
         2 . The buckle folding unit according to  claim 1 , which further comprises a control unit associated with said blown-air nozzle for activating said blown-air nozzle in a timed manner. 
     
     
         3 . The buckle folding unit according to  claim 1 , which further comprises a nozzle bar, said at least one blown-air nozzle including a plurality of blown-air nozzles disposed in a row in said nozzle bar. 
     
     
         4 . The buckle folding unit according to  claim 1 , wherein the sheet-shaped elements are introduced to said buckle plate along a plane of introduction, and said buckle plate is disposed at an angle of introduction of approximately 20° to 40° relative to said plane of introduction. 
     
     
         5 . The buckle folding unit according to  claim 1 , wherein at least a further roller of said folding roller pair not being said common roller has a surface and at least one channel formed in said surface. 
     
     
         6 . The buckle folding unit according to  claim 5 , wherein said surface of said further roller is a lateral surface, and said at least one channel is an endless circumferential channel formed in said lateral surface. 
     
     
         7 . A sheet-fed folding machine, comprising:
 at least one buckle folding unit according to  claim 1 .