Note: Descriptions are shown in the official language in which they were submitted.
lV~3214
This invention concerns improvements relating to the
production of smoke-filter components and filters for smoking
articles, particularly but not exclusively tobacco-smoke filter
components for cigarettes. It seeks especially to provide improved
methods and apparatus by which regions of rod-shaped material for
the production of such components can be substantially modified to
improve or adapt the rod for the purpose of achieving desired smoke-
filtration effects or characteristics and/or for the purpose of
facilitating manufacture.
Prior proposals relating to the manufacture of filters
from rod material have generally involved working on a continuous rod
or on a rod of multiple filter-plug length whilst it is moving in
the direction of its longitudinal axis, usually at high speed. This
gives rise to difficulties in manufacture due, for example, to the
limited time available for working on a rod moving at high speed,
to the necessity ~or precise timing and to the intermittent na-ture
of the operations to be performed on the rod.
According to the present invention, in a method or apparatus
~or shaping a rod component of a smoke filter, a rod of the material
to be shaped and a heated ~orming means are relatively moved in
contact with each other, in an arcuate path, in a direction trans-
verse to the 1ongitudinal axis o~ the rod, whereby an impression is
produced in the rod by the forming means. Preferably, the rod is
supported and conveyed for the relative movement at the periphery
of a drum-shaped inner rotor and -the fo~ming means comprises a
heated arcuate outer stator element or elements projecting inwardly
towards the rotor. Such an element may consist simply of a heated
bar having a rod-contacting profile complementary tothe impression
to be produced by it in the rod under the effects of heat and pres-
sure thereby applied.
Generally, in practice, the rod to be shaped will have alength which is a multiple of the length of an individual finished
component, for example of a filter plug. ~
3Z314
The rod may-or may not be also turned about its axis during
the relative movement in the direction transverse to that axis.
For this purpose, the rod may be supported at the periphery of the
rotor by means of a pair of rollers extending parallel to the long-
itudianl axis of the rod, the said rollers being rotated about their
axes for imparting to the rod turning movement about its axis.
Various impressed formations may be produced by the afore-
said method, for example and in a simple case one or more annular
grooves extending continuously around the rod. Generally the
impression will extend along a part o~ly of the length of the rod.
For producing a groove extending helically around the rod, the heated
stator element may be positioned at an angle other than a right angle ~ -
in relation to the transversely positioned rod~ -
Because the rod is operated upon whilst it is moving in a
direction transverse to its longitudinal axis, more time is avail-
able for working on the rod. Not only can a better shaping operation - -
be achieved in simple fashion and by simple means, but it is also
possible to manufacture economically a wide variety of filters with-
out the use of complicated and expensive machinery for pinching or
other operations which would require intermittency of movement in
the case of movement in the longitudinal ~irection. ;
The filter rods may be made of various filtering materials,
such as thermoplastic polymers, for example cellulose acetate or
polypropylene. Paper filters would be suitable if the paper was
wetted or contained a proportion of thermoplastic material or was
coated with heat-activated adhesive. The rod material may contain
additives such as carbon. It may consist of concentric tubes, for
instance an inner one of paper and an outer one of plastics material.
Parts at least of composite or multiple filter rods may be so produced,
even if not all of the sections are necessari:ly capable of permanent
deformation.
Before being shaped, the filter material or rod may be
sprayed or otherwise treated with a fluid additive, including water or
32~4
~eam, in order to condition the rod and minimise risk of damage to
the materials.
Preferably, the shaped rod is wrapped in wrapping material
while moving in a direction transverse to the longitudinal axis of
the rod. A simple wrapping operation can be thus achieved. Advan-
tageously, the aforesaid shaping and wrapping operations are performed
on a single machine or assembly, preferably in combination with a
filter-tip attaching unit or machine.
One manner of carrying out the invention will now be more
fully described, by way of example, with reference to the accompany-
ing diagrammatic drawings in which:
Figure 1 is a general end view of a complete filter-rod -
making machine, including forming and wrapping units,
Figure 2 is an elevational view, at right angles to Fig. 1
and to a larger scale, of the forming unit, and
Figure 3 is an end view, again to the larger scale,
illustrating the manner in which rods to be formed are suppor~d in the`
forming unit.
Figure L~ illustrates a filter rod formation producable by
the unit of Fig. 2, and
Figure 5 is a box diagram illustrating modes of use of the
machine.
The machine shown in Fig. 1 comprises a receiver drum 1
having in its circumferential surface longitudinal grooves 2 for
receiving through a chute 3, from a source (not shown), plain
cylindrical rods 4 of tobaccG-smoke filtering material, for example
cellulose acetate, and supplying the rods, retained in the grooves
in positions parallel to the drum axis by an arcuate guide 5, to
a rod-forming unit 6 hereinafter described. Transfer means, in the
form of three trans~er drums 7, 8 and 9 with arcuate guides 7t, 8~
and 97 serve to transfer filter rods 10, shaped in the unit 6, to a
wrapping unit 11, ~e rods retaining their transverse dispositions
thrQughout such transfer. The drums 7 and 8 are formed with longit-
udinal rod-receiving grooves similarly to the drum 1.
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` 1~432~
The unit 11 comprises a collating drum 12 and a wrapping
drum 13 which again have longitudinal rod-receiving grooves and
guides 121 and 13'. The drums 12 and 13 operate in per se known
manner. The drum 12 is fed with wrapping material, for example paper,
supplied in the form of a continuous web 14 from a reel (not shown) ~ ;
with the assistance of a roller 15. The latter co-operates with a
cutting roller 16 which carries a number of radially extending knives
17 at intervals appropriate for severing the web, whose width is
equal to the length of the rods 10, into separate lengths for wrapping
around the individual rods, which lengths are then fed by the roller
15 to the drum 12, one length being thereby collated with each rod ~ -
10 in known manner. ~he web 14 on its path from the reel to the
roller 15 is fed past an applicator (not shown) which applies adhesive
to that surface of the web which will be in contact with the rods.
Each length, carrying a coat of adhesive, is brought into contact
with a rod 10 carried at the periphery of the drum 12. The rods
10 pass, -together with their respective lengths of wrapping material,
from the drum 12 to the drum 13, where, in a position transverse to ; ~;
its axis, each rod is rotated about its axis without being moved
longitudinally and becomes wrapped in its respective said length,
the longitudinal edges being brought into contact so as to become
adhered together by the adhesive. From the drum 13, the wrapped
rods 18 are trans~erred to a catcher band 19 by a longitudinally
grooved transfer drum 20 having a guide 20~.
For operation of the machine, the drums 1, 7-9, 12, 13 and
20, rollers 15, 16 and band 19 are driven from a power source (not
shown) in co-ordination with each other and with the forming unit 6
now to be described.
The forming unit 6 consists of rotor and stator sections.
The rotor section comprises two circular end discs 21 (Fig.2) in
which are journalled a circular series of small rollers 22, which
pre~erably have knurled surfaces. Pairs of adjacent rollers 22
serve to receive rods from the drum 1 and to support them, between
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la43z~4
peripheral regions of the said rollers, while the rods are carried
through the unit by the turning of the rotor. The rotor is driven
by a shaft 23, suitably by an electric motor (not shown). A coupling,
indicated diagrammatically at 24, may be provided between the end
discs 21 -to facilitate axial adjustment of the unit to accommodate
di~erent lengths of rod to be shaped. Rotation of the rollers 22
about their axes is imparted through planet wheels 25 which are fast
on the extended journals at one end and mesh with a sun wheel 26.
The sun wheel 26 is rotationally fast on a shaft 27 driven by another
motor (not shown). If, as shown3 the adjacent disc 21 is supported
by way of a stub 2~ in a bearing 29 in the wheel 26 and/or shaft 27, ~-
provision may again be made, as indicated diagrammatically at 30,
~or some relative axial adjustment. The motors may be controllable-
speed motors, so that the revolution speed of the rotor and the
revolution speed of the rollers about their axes can be selected to
suit requirements, more particularly so that the nMmber of revolution -
of the rods during their passage past the stator can be varied or
~ontrolled. If this facility is not required, drives for the
rotation of the rotor and for the rotation of the rollers about their
axes may be derived from a common source.
The stator section comprises an outer arcuate member 31
havlng radially inwardly projecting portions 32 in the form of
arcuate ribs. The member 31 is provided, at least in the projecting ;
portions, with heating means, preferably in the form of electrical
elements embecLded therein per se known manner. The number, shape
and disposition of -the projecting portions will be complementary to
recLuirecL depressions 33 to be ~ormed in the rod 10. The shape of
rod shown in Fig. 4, to which the cross-sectional stator shape shown
in Fig. 2 is complementary is given purely by way of example.
Arcuate guides 34 (Fig.1) extend from the encLs of the member 31 to
points adjacent to -the drums 1 and 7 respectively.
The member 31 and its projecting portions 32 will generally
extend at a constant radial distance from the axis of the rotor.
-" ~043Z~4 :
owever, the proximity ~f the said por-tions 32 to the rotor may
increase in the direction of rotation so that the shaping effect is
progressive.
In operation of the unit 6, rods deposited one by one from
the drum 1 between pairs of rollers 22 are carried by the rotation
of the rotor past the stator member 31 while being rotated about
their axes by the rotation of the rollers 22. The rota-ting rods 10
are thereby pressed against the projecting stator portions, e.g. 32,
so that annular depressions or spaced-apart zones of reduced diameter,
e.g. 33, are formed in the rods under the effects of heat and
pressure.
It is preferred to employ means for rotating the rods about
their axes by positively driving the rollers 22. For some purposes,
however, the rods may be rotated as a result only of their contact
with the stator member 31.
Provision may be made for controlling the stator heating
means. The required temperature of the projecting portions 32 will
depend upon the characteristlcs of the material of the rods and
their residence time in the stator. It should be between the soften-
ing and scorching temperatures of that material. It would be belowthe scorching temperature of paper, if the rod were already paper-
wrapped when shaped. It is an advantage of the arrangement de~cribed
that the residence time can be made long, whereby lower temperatures
can be employed and risk of damage to the fil-ter material and any
wrapping can be reduced.
If it is re~uired that parts of the surface of the rod,
whether external cylindrical surfaces or bottom and/or side surfaces
o~ grooves or other depressions, should be partially or completely
sealed against the pene-tration of smoke cons~ituents into the rod,
this may be achieved by making the stator te~perature in a required ;
region or regions su~ficiently high to produce local superficial
fusion and resultant partial or complete sealing of the rod material.
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32~4
In practice, rods ~0 of the length of a single filter will
not normally be shaped in the unit 6, but rather rods of a length
which is a multiple, for instance six, of -the single length, such
rods being subsequently cu-t into the single lengths.
A forming unit such as has been described can be utilised
for producing various kinds of shapes of filter elements or parts
thereof. Annular-groo~es may be of rectangular section, as shown
in Fig. 4 or of rounded, V or other section, and may be provided
in any required sizes, dispositions and numbers and with constant
or varying depth and/or width. In effect a generally cylindrical
rod body with outwardly projecting annular ribs may be obtained.
Non-annular formations, for example a helical groo~e or grooves,
may be produced by the use on the stator of projecting portions which
are in a plane at an angle other than a right angle to the transverse
direction in which the rods extend as they are carried, rotating
slowly about their axes, but without axial mo~ement, through the
unit 6, the pitch of the helix being dependent upon the said angle. `
Filter end formations may be produced, for example conical, crowned ;
or oblique ends or ~olded, corrugated or finned ends, possibly in
con~unction with at least partial sealing of such ends. Shaping may
be applied primarily or partially with the object of achieving
di~erential compaction or packing factor (the proportion of filter
volume occupied in the case o~ a fibrous filter material). For
instance a cylindrical rod portion may be adjoined by a compacted
tapering portion. `:
Formations may be produced which do not extend around the
whole circumference and which may be staggered circumferentially
in relation to each other. Depressions bounded at the bottom by ~ ;
a chordal boundary may be obtained. Such formations can be produced
by selection of lengths, shapes and positions of the projecting
stator formations and of the speed o~ rotation of the rotor~ For
some purposes, the rods will not be allowed to turn about their axes
as the rotor rotates, whereby a depression will be produced on one
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~1432~4
_ide only of the rod. A similar depression can b~ produced on the
opposite side by turning the rod over or feeding it to a second
forming unit 6.
Formations such as have been referred to can be produced
in conjunction with an internal cavity and with either a closed
or open end or ends by using initially hollow or tubular rod material.
Longitudinal formations can be produced, either alone or
in conjunction with circumferential ~ormations, by using projecting
stator portions which extend transversely of the stator. A pattern
of longitudinal depressions, cavities or perforations, ribs or teeth,
including staggered grooves, can be thus produced, if required in
combination with circumferential depressions.
For many purposes, required formations can be produced
using a single forming unit 6 as the rod shaping means. However,
more than one forming unit may be employed to perform different
shaping operations or to complete one operation in more than one
stage. Parts of a filter element may be shaped by separate forming
units and brought together subsequently.
For example, for filters with ribbed bodies enclosed within
a hollow cylinder, the latter may be closed by a conically terminated
plug portion produced in the above described manner. Composite
~ilters may, for i~stance, comprise plain acetate plugs at the ends
with a carbon-filled acetate portion in the middle, -the latter being
compressed, so as to form an annular path through which the smoke
can flow past the carbon instead of through it. A high-performance
filter with a cellulose-acetate filtration character may comprise
two solid cylindrical bodies wi-th conical adjacent ends assembled
with a plain hollow cylindrical filter body of smaller diameter
between them.
The invention makes possible the pro~uction, at high speed,
of a number of filters which could only be made otherwise, if at all,
with great difficulty and by expensive means and at comparatively
low speedsO It also increases the versatility of a ~ilter rod-making
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.achine, as one type of rod-shaping device can readily be replaced
by another in the same basic machine.
A rod-shaping and wrapping machine such as has been described
with reference to Figs. 1 to 4 may be used in various ways and in
close combination with other apparatus. As illustrated, it is
supplied with pre - cut rods 4 from a stock and the shaped and
wrapped rods 18 are delivered to stock by the band 19. As illustra~d
diagrammatically in Fig. 5, however, the rod forming and wrapping
machine or unit 35 may be combined or assembled with a known rod
producing machine or unit 36, for example a machine to which a
filter material, for example a tow of cellulose acetate, is supplied
at 37 and from which rods 4 produced and cut therein are supplied
at 38 to the machine 35. For this purpose, the usual fluted drum
employed in the known rod-producing machine for catching and ar~est-
ing longitudinally moving rods and moving them off in a direction
transverse to their axes may be simply replaced by means for feeding
the rods to the rotor o~ the unit 6 in Fig. 1. Alterna-tively the
unit 6 may be disposed adjacent to the catcher drum and the rods
~ed ~rom the latter to the said unit. With either of the above
arrangements, instead of feeding the rods 18 from the machine 35
to stock, they may be supplied at 39 directly to a filter-tip
attaching machine or unit 40 to which wrapped rods 41 of cigarette
tobacco are supplied at 42 either from stock or, advantageously,
directly ~rom a known cigarette-making machine 43. me machine or
unit 40 is so devised, as in the case of the rod forming and
wrapping machine described with reference to Figs. 1 to 4, that the
rods 18 pass through it in the transverse position. As diagram-
matically indicated, the tobacco rods 41 are fed in an axial position
from the machine 43 to the unit 40 which is :Located, with the unit
35, laterally in relation to the machine 43. The rods 41 are thus
presented in a position appropriate for co-axial assembly with the
shaped filter rods 18. In the unit 40, the tobacco rods 41 and the
filter rods 18 may be assenbled by per se known means.
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The units 35 and 40 may form an assembly which can be applied
in simple fashion to the machine 43 and driven in co-ordination there-
with.
For producing dual-section or multiple-section ~ilters, the
shaped rods 10 may be cut into individual section lengths before
being wrapped, means being provided for interposing other cut filter
sections supplied from a different source. For each filter, one
each of the said section lengths and other sections are assembled
in a single wrapping.
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