Folding Machine with Suction Means for Zig-Zag Folding a Continous Web Material and Associated Folding Method

Abstract

The folding machine comprises; a pair of counter-rotating folding cylinders ( 1, 3 ), each provided with at least one gripping member ( 43 ) to fold a continuous web material (N) in a zigzag manner; and a cutting member ( 60 ) disposed in front of the folding cylinders to cut the zigzag folded web material and divide it into two piles (M) of folded articles. Each gripping member is a suction member which retains the web material by suction at the level of the respective folding line.

1 . A folding machine comprising: a pair of counter-rotating folding cylinders ( 1 ,  3 ), each provided with at least one gripping member ( 43 ) to fold a continuous web material (N) in a zigzag manner; a cutting member ( 60 ) disposed in front of said folding cylinders to cut the zigzag folded web material and divide it into two piles (M) of folded articles; characterized in that each gripping member is a suction member which retains the web material by suction at the level of the respective folding line. 
   
   
       2 . Folding machine as claimed in  claim 1 , characterized in that each folding cylinder ( 1 ,  3 ) has a wedge element ( 57 ) in phase with the gripping member of the opposed cylinder, to produce a line which facilitates folding in the web material, at the level of said gripping member. 
   
   
       3 . Folding machine as claimed in  claim 2 , characterized in that said wedge element ( 57 ) cooperates with a notch ( 55 ) associated with the gripping member ( 43 ) with which said wedge element is in phase. 
   
   
       4 . Folding machine as claimed in  claim 3 , characterized in that said notch is produced in an interchangeable insert. 
   
   
       5 . Folding machine as claimed in  claim 4 , characterized in that said interchangeable insert is produced in an elastically yielding material. 
   
   
       6 . Folding machine as claimed in one or more of the previous claims, characterized in that each of said gripping members ( 43 ) has at least one alignment of suction holes ( 45 ), said alignment extending parallel to the axis ( 1 A,  3 A) of the respective folding cylinder ( 1 ,  3 ). 
   
   
       7 . Folding machine as claimed in  claim 6 , characterized in that it has, for each gripping member, a plurality of alignments of suction holes ( 45 ). 
   
   
       8 . Folding machine as claimed in  claim 3  and  6 , characterized in that each of said notches ( 55 ) is disposed at the level of a respective alignment of suction holes ( 45 ). 
   
   
       9 . Folding machine as claimed in one or more of  claims 6  to  8 , characterized in that said suction holes ( 45 ) of each folding cylinder are produced in a block ( 43 ) housed in a seat ( 41 ) of the respective folding cylinder ( 1 ,  3 ). 
   
   
       10 . Folding machine as claimed in one or more of the previous claims, characterized in that means to synchronize suction with the angular position of the respective folding cylinder ( 1 ,  3 ) are associated with each of said suction gripping members ( 43 ). 
   
   
       11 . Folding machine as claimed in one or more of the previous claims, characterized in that oscillating bars ( 26 ,  35 ) housed in annular grooves ( 27 ,  37 ) of the respective cylinder are associated with each folding cylinder, to cause detachment of the folded web material from the folding cylinders. 
   
   
       12 . A method for producing folded articles (M) from a continuous web material (N) comprising the steps of: feeding the continuous web material into a nip ( 5 ) defined between two counter-rotating folding cylinders ( 1 ,  3 ), each provided with at least one gripping member ( 43 ); folding the web material in a zigzag manner by means of said folding cylinders, engaging the web material with the gripping members of one and of the other of said folding cylinders alternately; feeding the zigzag folded web material towards a cutting member ( 60 ); by means of said cutting member ( 60 ), cutting the zigzag folded web material into two piles of folded articles (M); characterized in that the web material is retained and folded in said folding cylinders by suction. 
   
   
       13 . Method as claimed in  claim 12 , characterized in that crease lines are produced mechanically in the web material at the level of said gripping members, which retain the web material by suction. 
   
   
       14 . Method as claimed in  claim 13 , characterized in that said crease lines for facilitating folding are produced by means of said two folding cylinders. 
   
   
       15 . Method as claimed in  claim 14 , characterized in that said crease lines for facilitating folding are produced by interpenetration of a wedge element ( 57 ) and a notch ( 55 ), produced on one and on the other of said two folding cylinders, with the web material (N) disposed between said wedge element ( 57 ) and said notch ( 55 ). 
   
   
       16 . Method as claimed in one or more of  claims 12  to  15 , characterized in that said web material is tissue paper.