Rewinding machine and winding method

Abstract

The rewinding machine includes a weakening device for weakening the web material along a substantially transverse weakening line, along which the web material is severed at the end of the winding of a log. The weakening device is controlled so as to generate the weakening line in a manner synchronized with the completion of winding of the log.

1 - 26 . (canceled) 
     
     
         27 . Rewinding machine for producing logs of web material, comprising a feed path of a web material, a winding cradle and a perforator, which forms perforation lines in said web material in order to divide said web material into single sheets that can be detached along said perforation lines; and said rewinding machine further comprising a weakening device for weakening the web material along a substantially transverse weakening line, along which the web material is severed at an end of winding of a log, said weakening device being arranged to generate said weakening line in a manner synchronized with the end of winding of said log and substantially matching one of said perforation lines. 
     
     
         28 . The rewinding machine as claimed in  claim 27 , wherein said weakening device comprises an applicator for applying a liquid along said weakening line. 
     
     
         29 . The rewinding machine as claimed in  claim 28 , wherein said applicator applies water along said weakening line. 
     
     
         30 . The rewinding machine as claimed in  claim 28 , wherein said applicator applies a liquid containing an adhesive along said weakening line. 
     
     
         31 . The rewinding machine as claimed in  claim 27 , further comprising a winding core inserter. 
     
     
         32 . The rewinding machine as claimed in  claim 31 , further comprising a glue applicator for applying glue on said winding cores. 
     
     
         33 . The rewinding machine as claimed in  claim 27 , wherein said weakening device comprises a rotating element with a liquid dispenser, said rotating element being synchronized with the winding of the log in order to apply said liquid along the weakening line at the end of winding of each log. 
     
     
         34 . The rewinding machine as claimed in  claim 33 , wherein said rotating element cooperates with a rotating roller supporting the web material, whose peripheral speed is substantially equal to speed of the web material at least during application of the liquid by said liquid dispenser. 
     
     
         35 . The rewinding machine as claimed in  claim 33 , wherein said applicator is arranged to come into contact with the web material resting on a rotating roller in a manner synchronized with movement of the web material, during the contact a transferring system having a speed substantially equal to the speed of the web material at the contact. 
     
     
         36 . The rewinding machine as claimed in  claim 34 , wherein said applicator is arranged to come into contact with the web material resting on said rotating roller in a manner synchronized with movement of the web material, during the contact a transferring system having a speed substantially equal to the speed of the web material at the contact. 
     
     
         37 . The rewinding machine as claimed in  claim 34 , wherein the feed path of said web material develops around said roller, the web material being guided around said roller. 
     
     
         38 . The rewinding machine as claimed in  claim 35 , wherein the feed path of said web material develops around said roller, the web material being guided around said roller. 
     
     
         39 . The rewinding machine as claimed in  claim 34 , wherein said rotating roller constitutes one of a plurality of winding rollers forming said winding cradle. 
     
     
         40 . The rewinding machine as claimed in  claim 35 , wherein the feed path of said web material develops around said rotating roller, the web material being guided around said rotating roller. 
     
     
         41 . The rewinding machine as claimed in  claim 37 , wherein the feed path of said web material develops around said rotating roller, the web material being guided around said rotating roller. 
     
     
         42 . The rewinding machine as claimed in  claim 27 , wherein said winding cradle comprises a first winding roller around which said web material is fed and guided, and a second winding roller forming with said first winding roller a nip for transit of winding cores in an initial phase of a winding cycle; and wherein said weakening device is arranged to act upstream of said nip relative to a direction of feed of the web material. 
     
     
         43 . The rewinding machine as claimed in  claim 42 , further comprising a rolling surface arranged around the first winding roller and upstream of said nip relative to the direction of feed of the web material, defining a channel between said first winding roller and said rolling surface, and wherein said weakening device is arranged to act on the web material upstream of said channel. 
     
     
         44 . The rewinding machine as claimed in  claim 43 , further comprising a core inserter arranged to feed said winding cores into said channel. 
     
     
         45 . The rewinding machine as claimed in  claim 42 , wherein said first winding roller has apertures for exit of air therefrom so as to facilitate detachment of a free end of the web material. 
     
     
         46 . The rewinding machine as claimed in  claim 39 , wherein said one of a plurality of winding rollers has a knurled surface or an engraved surface. 
     
     
         47 . The rewinding machine as claimed in  claim 27 , further comprising a blowing system to facilitate winding of a first turn of web material around a winding core. 
     
     
         48 . The rewinding machine as claimed in  claim 27 , further comprising a first glue applicator and a second glue applicator, to apply glue on winding cores in two angularly offset areas, a first area coming into contact with a portion of the web material forming a tail of a complete log and a second area coming into contact with a portion of the web material forming an initial part of a new log of web material. 
     
     
         49 . The rewinding machine as claimed in  claim 27 , wherein said weakening device comprises a mechanical system or a pneumatic system synchronized with a winding cycle of the logs. 
     
     
         50 . A method for winding rolls of web material around winding cores, comprising:
 feeding the web material along a feed path;   subdividing said web material into single portions that can be detached along transverse perforation lines;   winding a quantity of the web material in order to form a first log of web material;   when a given quantity of web material has been wound on said log, severing the web material in a severing position along said feed path, forming a tail portion of the first log and a head portion for starting the winding of a second log;   starting the winding of said second log;   
       wherein
 at end of the winding of said log, in a weakening position arranged along the feed path of the web material upstream of the severing position, a weakening line is formed on the web material at one of said transverse perforation lines; 
 the web material is fed along said feed path moving said weakening line towards said severing position; and 
 the web material is severed in said severing position. 
 
     
     
         51 . The method as claimed in  claim 50 , further comprising winding said logs around winding cores. 
     
     
         52 . The method as claimed in  claim 50 , further comprising gluing the head portion of the web material on a winding core at start of the winding of each log. 
     
     
         53 . The method as claimed in  claim 50 , further comprising weakening said web material by applying a liquid along said weakening line. 
     
     
         54 . The method as claimed in  claim 51 , further comprising weakening said web material by applying a liquid along said weakening line and wherein said liquid also serves to anchor the head portion of the web material on the winding core. 
     
     
         55 . Rewinding machine for producing logs of web material, comprising a feed path of a web material, a winding cradle, and weakening device; said weakening device comprising an applicator for applying a liquid along a substantially transverse weakening line for weakening the web material along said weakening line, along which the web material is severed at end of winding of a log, said weakening device serving to generate said weakening line in a manner synchronized with the end of winding of said log. 
     
     
         56 . Method for winding rolls of web material around winding cores, comprising:
 feeding the web material along a feed path;   winding a quantity of the web material in order to form a first log of web material;   when on said log a given quantity of the web material has been wound, severing the web material in a severing position along said feed path, forming a tail portion of the first log and a head portion for starting winding of a second log;   starting the winding of said second log;   
       wherein
 at end of the winding of said log, in a weakening position arranged along the feed path of the web material upstream of the severing position, a weakening line is formed on the web material by applying a liquid along said weakening line; 
 feeding the web material along said feed path moving said weakening line towards said severing position; 
 and severing the web material in said severing position.