Unit and a method for forming a continuous cigarette rod in a cigarette maker

Abstract

A continuous cigarette rod is prepared by a unit comprising a looped conveyor on which a continuous stream of tobacco particles advances toward the entry point of a forming station where the rod is assembled. Also forming part of the unit, ordered in sequence along a predetermined feed path, are a first trimming device designed to produce a cyclical skimming action, a compactor device operating synchronously with the first trimming device, serving to increase the density of the stream selectively at points coinciding with the portions skimmed by the first trimming device, and a second trimming device by which the thickness of the stream is reduced uniformly to a prescribed value.

1 ) a unit for forming a continuous cigarette rod in a cigarette making machine, comprising a conveyor serving to feed a continuous stream of tobacco particles toward the entry point of a station where the cigarette rod is formed, advancing in a predetermined direction along a predetermined feed path, and incorporating, ordered in sequence along the feed direction, a first trimming device designed to reduce the thickness of the advancing stream, means serving to densify predetermined portions of the stream, and a second trimming device, wherein the first trimming device operates cyclically and synchronously with the densifying means, and is designed to reduce the thickness of the stream at given portions corresponding to the predetermined densified portions.  
   
   
       2 ) A unit as in  claim 1 , wherein the first trimming device comprises a rotating knife capable of movement cyclically between a position of interference with the stream and a position distanced from the stream.  
   
   
       3 ) A unit as in  claim 2 , wherein the first trimming device also comprises a striker element against which the rotating knife locates when assuming the position of interference with the stream.  
   
   
       4 ) A method as in  claim 3 , wherein the rotating knife comprises a disc rotatable about its own center, of which the peripheral edge presents at least one radial blade occupying only a part of the selfsame peripheral edge.  
   
   
       5 ) A unit as in  claim 4 , wherein the striker element is afforded by a wall set transversely to the plane occupied by the disc.  
   
   
       6 ) A unit as in  claim 4 , wherein the striker element is capable of reciprocating motion parallel to the predetermined direction followed by the stream and synchronously with the rotating knife, so as to accompany the movement of the blade and avoid sliding contact therewith.  
   
   
       7 ) A unit as in  claim 3 , wherein the conveyor comprises an aspirating belt of which a bottom branch is designed to retain the tobacco particles by suction, also a pair of side walls positioned to coincide at least with the first trimming device and projecting from opposite edges of the bottom branch of the aspirating belt in such a way as to establish a channel that serves to confine the advancing stream and is enclosable by a bottom wall afforded by the rotating knife when in the position of interference with the stream.  
   
   
       8 ) A unit as in  claim 6 , wherein one of the side walls is provided by the striker element.  
   
   
       9 ) A unit as in  claim 1 , further comprising means by which to recover the shredded tobacco removed by trimming.  
   
   
       10 ) A method of forming a continuous cigarette rod in a cigarette maker, comprising the step of feeding a continuous stream of tobacco particles to the entry point of a forming station where the cigarette rod is assembled, advancing in a predetermined direction along a predetermined path, also the steps of subjecting the stream to a first trimming action, then densifying predetermined portions of the stream and thereafter subjecting the stream to a second trimming action, wherein the first trimming step serves to reduce the thickness of the stream of tobacco along given portions corresponding to the predetermined densified portions.