Tobacco – Plug or compressed shape making – With cutting
Patent
1985-07-15
1987-10-20
Millin, V.
Tobacco
Plug or compressed shape making
With cutting
131117, A24B 307
Patent
active
047007206
DESCRIPTION:
BRIEF SUMMARY
This invention relates to a knife for a cutting machine particularly but not solely for cutting tobacco.
The machine used for cutting the tobacco is of the well known type in which the leaf is fed into a convergent throat of rectangular cross section formed by two parallel plates and two converging conveyor bands or by two parallel plates and two converging roller conveyors. At the convergent end of the throat is a mouthpiece. The leaf is fed into the throat at the divergent end and is driven by the conveyor bands or rollers towards the mouthpiece, where the leaf is cut as it issues from the mouthpiece either by a single knife caused to reciprocate across the mouthpiece by one or more knives arranged in a holder which rotates on an axis either at right-angles or parallel to the axis of the throat, so that the cutting edge of the knife or knives are caused to pass across the mouthpiece. The convergence of the throat compresses the leaf sufficiently so that it may be cut and not pulled from the mouthpiece. One of the two band or roller conveyors is free to move and pressure is applied to it so that the compression of the leaf can be regulated. The width of cut of the shreds can be adjusted by altering the conveyor speed and hence the distance the compressed leaf is fed through the mouthpiece between cuts by the knife or knives.
STATEMENT OF PRIOR ART
A cross-cutting knife for such a machine is disclosed in U.S. Pat. No. 1,195,163 and comprises a plate having one surface bevelled to produce a cutting edge and a plurality of grooves formed at right angles to the cutting edge in the surface of the knife which is not bevelled thereby providing a crenellated cutting edge.
By this design the knife can simultaneously produce a first cut and a cross-breakage with a single passage of the knife through the leaf. With this knife, the leaf only passes once through a cutting machine thus avoiding a second compression and produces a very much more uniform cut.
The knife described in British Pat. No. 1,195,163 works very well when the grooves are 1/8"-3/8" (3.2-9.6 mm) wide at 1/4"-3/4" (6.35-18.9 mm) pitch. However, the length of pieces required in cigarette tobacco filler or similar products can be as large as 1.5" (38.1 mm).
Rectangular section grooves at right angles to the cutting edge at a pitch 1.5 to 2 times the groove width have been used in an attempt to cut controlled length pieces in the range 5/16"-1.5" (8-38.1 mm) with the result that piece lengths greater than that required were often present in the product, more noticeably so as the control length increased.
When the rectangular blade as described in UK Patent No. 1,195,163 passes through the tobacco portions of the lamina at the leading cutting edge are displaced away from the main body of tobacco (or cheese). Consequently the displaced pieces of lamina elongates by an amount equal to twice the displacement. If F is the displacement and the width of the leading cutting edge is G then the displaced pieces are each elongated to a length equal to G+2F or else they break. The induced strain, which is the elongation divided by the original length, is therefore 2F.div.G. However, the cut piece may break, most predictably at a sharp corner of the leading cutting edge with the consequence that a strand can be as much as three times larger than required i.e., breaks could occur at the two sharp corners of two adjacent leading cutting edges, which corners are remote from each other; the strand therefore comprising the two pieces of lamina displaced by the adjacent leading edges and the piece between them displaced by the trailing cutting edge.
OBJECT OF THE INVENTION
An object of the invention is to provide a blade that will predictably break the strands at desired positions along the blade edge whereby definitive lengths of strand can be achieved irrespective of pitch.
SUMMARY OF THE INVENTION
According to the invention there is provided a knife for a cutting machine comprising a plate having two major surfaces, one major surface being bevelled to form a c
AMF Incorporated
Millin V.
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