Method and Apparatus for Forming Tobacco Rods

Abstract

A method of forming tobacco rods comprises providing an endless bead of tobacco, creating regularly spaced apart gaps ( 14 ) with no tobacco along the length of the bead, wrapping the bead in an endless length of paper wrapper ( 16 ), and cutting through the paper wrapper where it overlays the gaps in order to divide the wrapped bead into individual tobacco rods. The gaps may be created using an ecreteur with trimmer discs configured to trim away the full width of the tobacco rod ( 10 ), or by using a rotating screw thread extending into the tobacco.

1 . A method of forming tobacco rods suitable for the manufacture of tobacco products with at least one closed end, the method comprising:
 providing an endless bead of tobacco;   creating tobacco-less gaps in the bead, the gaps regularly spaced apart along the bead;   wrapping the bead in an endless length of paper wrapper; and   dividing the wrapped bead into tobacco rods by cutting through the paper wrapper where it overlays the gaps.   
     
     
         2 . The method according to  claim 1 , wherein:
 each gap has a length equal to twice a length of paper wrapper required for subsequent folding over the tobacco; and   dividing the wrapped bead comprises cutting through the paper wrapper at the longitudinal mid-point of each gap.   
     
     
         3 . The method according to  claim 2 , wherein the gaps are spaced apart by a distance equal to twice a length of tobacco intended for smoking articles to be made from the tobacco rods. 
     
     
         4 . The method according to  claim 3 , further comprising dividing the tobacco rods longitudinally in half by cutting through at the longitudinal mid-point of each tobacco rod. 
     
     
         5 . The method according to  claim 2 , in which the gaps are spaced apart by a distance equal to a length of tobacco intended for smoking articles to be made from the tobacco rods. 
     
     
         6 . The method according to  claim 1 , wherein:
 each gap has a length equal to a length of paper wrapper required for subsequent folding over the tobacco;   the gaps are spaced apart by a distance equal to a length of tobacco intended for smoking articles to be made from the tobacco rods; and   dividing the wrapped bead comprises cutting through the paper wrapper substantially flush with one end of each gap.   
     
     
         7 . The method according to  claim 1 , wherein creating the tobacco-less gaps in the bead comprises removing tobacco from the bead. 
     
     
         8 . The method according to  claim 7 , wherein removing the tobacco from the bead comprises trimming away the full width of the tobacco in the bead over the length of each gap using an ecreteur. 
     
     
         9 . The method according to  claim 1 , wherein creating the tobacco-less gaps in the bead comprises dividing the bead into longitudinal portions of tobacco and moving the portions apart. 
     
     
         10 . The method according to  claim 9 , wherein dividing the bead and moving the portions of tobacco apart comprises:
 bringing a screw thread which is rotating about an axis parallel to the length of the bead into contact with the bead while the bead is traveling longitudinally, the screw thread having a thread with a thickness which increases with distance along the screw thread.   
     
     
         11 . The method according to  claim 10 , wherein the screw thread has a thread which commences from a point at the leading end of the screw thread, the thread having a radius that increases with distance along the screw thread from a point over at least part of the length of the screw thread. 
     
     
         12 . The method according to  claim 10 , in which the screw thread has a thread which commences from a leading edge arranged substantially along a radius of the thread, the thread having a substantially constant radius. 
     
     
         13 . The method according to  claim 9 , wherein dividing the bead and moving the portions of tobacco apart comprises:
 moving at least one rotating disc into and out of the bead, the disc rotating about an axis parallel to the bead and having a thickness that increases from the edge to the centre of the disc.   
     
     
         14 . An apparatus for forming tobacco rods suitable for manufacture of tobacco products with at least one closed end, the apparatus comprising:
 a conveying device for supporting and conveying an endless bead of tobacco;   a tobacco spacing device operable to create regularly spaced apart tobacco-less gaps in the bead;   a garniture and a paper wrapper supply arranged to receive the bead after the creation of the gaps and wrap the bead in an endless length of the paper wrapper; and   a cutter operable to divide the wrapped bead into tobacco rods by cutting through the paper wrapper where it overlays the gaps.   
     
     
         15 . The apparatus according to  claim 14 , wherein the tobacco spacing device creates the gaps by removing tobacco from the bead. 
     
     
         16 . The apparatus according to  claim 15 , wherein the tobacco spacing device comprises an ecreteur having at least one trimmer disc with a circumference height profile configured to trim away the full width of tobacco in the bead over the length of each gap. 
     
     
         17 . The apparatus according to  claim 14 , wherein the tobacco spacing device creates the gaps by dividing the bead into longitudinal portions of tobacco and moving the portions apart. 
     
     
         18 . The apparatus according to  claim 17 , wherein the tobacco spacing device comprises a screw thread rotatable about an axis parallel to the length of the bead such that a thread of the screw thread passes through the bead as it is carried by the conveying device, the thread with a thickness which increases with distance along the screw thread. 
     
     
         19 . The apparatus according to  claim 18 , wherein the screw thread has a thread which commences from a point at the leading end of the screw thread, the thread having a radius that increases with distance along the screw thread from the point over at least part of the length of the screw thread. 
     
     
         20 . The apparatus according to  claim 18 , wherein the screw thread has a thread which commences from a leading edge arranged substantially along a radius of the thread, the thread having a substantially constant radius. 
     
     
         21 . The apparatus according to  claim 17 , wherein the tobacco spacing device comprises at least one disc rotatable about an axis parallel to the bead and movable into and out of the bead while rotating, the disc having a thickness that increases from the edge to the centre of the disc.