Note: Descriptions are shown in the official language in which they were submitted.
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COMPOSITE WEB FORMING METHOD
Field of the Invention
The present invention relates to a composite web forming method, and more
particularly to a method for handling a glass fiber web used in the
manufacture of
smoking articles similar to conventional cigarettes.
B~ck~round of the Invention
Smoking articles are known which have a fuel element is attached to one end
thereof to provide heat generation for operation of the smoking article. The
fuel
element comprises a carbonaceous fuel rod wrapped in a glass fiber web and
overwrapped with a paper wrapper or plug wrap. Such smoking articles are
disclosed,
for example, in U.S. Patent Nos. 4,714,082; 4,756,318; and 5,056,776 assigned
to the
assignee of the present invention.
In one method of making the fuel element of such smoking articles, a web of
reconstituted tobacco paper is disposed between two identical webs of a glass
fiber
material to form a composite web which is then wrapped about a continuously
extruded
carbonaceous fuel rod and overwrapped with a paper wrapper which may also be
tobacco paper, as described in European Patent Application No. 562,474,
published
September 29, 1993. In order to economically produce such smoking articles, it
is
necessary to form the various components of the smoking article in a
continuous process
at high production rates.
Conventional cigarette making machinery typically operates at the high
production rates contemplated by the present invention. One conventional
apparatus for
making cigarette filters, known as KDFTM filter maker, may be employed in the
manufacture of fuel elements for the smoking articles described in the
aforesaid patents.
However, the apparatus upstream of the KDFTM filter for supplying the
components of
the fuel element is substantially different from that used to make
conventional cigarette
filters. The present invention is directed to that apparatus and, in
particular, to the
various components of the apparatus for forming the aforesaid composite web
from rolls
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of glass fiber material and tobacco paper and supplying the composite web to
the KDF
filter maker for making the fuel element of the smoking article.
The present invention is concerned with the handling of different web
materials
used to form a continuous composite web for manufacturing the fuel elements
for the
above-described smoking articles. In particular, the fuel element constructed
with the
apparatus and method of the invention may be that disclosed in the
aforementioned U.S.
Patent No. 5,065,776 to Lawson et al.
The components of the fuel element comprise an extruded carbonaceous rod, a
glass fiber web which may be composed of Owens-Corning C-glassTM mat having an
uncompressed thickness of about 1.0 mm and a width of about 38 mm, a web of
reconstituted tobacco paper having a thickness-of about 0.13 mm and a width of
about
19 mm and a web of paper similar to a plug wrap having a thickness of about
0.13 mm
and a width of about 26.5 mm. The carbonaceous rod may have a composition
described in the aforesaid U.S. Patent No. 5,065,776 and is continuously
extruded from
a screw-type extruder and delivered via an elongated V-shaped trough to a KDF
filter
maker where it is wrapped with a composite web formed from the above-described
glass
and tobacco paper webs, then overwrapped with the paper wrap.
The apparatus of the invention comprises a web unwinder that supports two
bobbins of wound C-glass mat material slit into web widths of about 38 mm with
approximately ten individual webs per bobbin. The glass webs are drawn
alternately
from the two bobbins and are automatically spliced together to provide a
continuous
supply of glass web. The web unwinder indexes the bobbins transversely so that
the
webs being unwound are aligned with the web feed path through the apparatus.
Upon
depletion of the last web on one bobbin that bobbin is replaced with a full
bobbin during
unwinding of the web on the other bobbin so that operation of the overall
proceeds
continuously without stoppage even during bobbin replacement.
The webs of both bobbins are threaded about rollers and a control dancer for
feeding to a splicer apparatus located downstream of the unwinder. Just prior
to the
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splicing operation, the depletion state of the web being unwound from a first
bobbin
is sensed and the web unwind speed is increased to fill a web reservoir
downstream of
the splicer with sufficient web material to permit web unwinding to stop so
that the
splicing operation can proceed. When the trailing end of a web being unwound
from
the first bobbin passes into the splicer, unwinding is temporarily stopped and
the
trailing end of the just-unwound web is automatically spliced to the leading
end of the
next web to be unwound from the second bobbin.
The splicer apparatus includes clamps for holding the webs and cutters for
squaring the ends of the webs to be spliced. Upper and lower tape applicators
in the
splicer apparatus are loaded by an operator with short sections of splicing
tape and
when the ends of the leading and trailing webs are in position slightly spaced
apart and
clamped, the tape is automatically applied to the upper and lower surfaces of
the webs
to effect the splice and the tape applicators and clamps are retracted. A
capstan roller
downstream of the splicer then pulls the spliced web through the splicer and
the web
is payed out from the second bobbin. The operator then loads the leading end
of the
next web from the first bobbin and the splicing tape sections into the splicer
apparatus
in preparation for the next splice.
During the splicing operation, the accumulated glass web in the web reservoir
is taken up so that the KDF filter maker continuously runs at a high
production speed
even when the web is temporarily stopped for splicing. From the web reservoir,
the
glass web is fed to a slitter where it is slit longitudinally into two equal
widths of about
19 mm each. The two webs are then guided by a roller system into vertically
spaced
paths. A web of tobacco paper also having a width of about 19 mm is payed off
a
bobbin and guided by the roller system to a position intermediate the two
glass webs.
The axes of the three webs are initially transversely offset from one another,
but are
guided by the roller system into alignment one over another and then into
contact with
one another with the tobacco web sandwiched between the two glass webs to form
a
composite, three-layer web. The composite web is then guided into the KDF
filter
maker where it is wrapped about the extruded carbonaceous fuel rod,
overwrapped with
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the paper wrap and glued along a longitudinal seam in a manner similar to
wrapping and
gluing a plug wrap about a conventional cigarette filter.
According to the invention there is provided a method of continuously forming
a
composite web for use in the manufacture of a smoking article comprising the
steps of:
unwinding a first glass fiber web having a given width from a first bobbin,
along
a path of travel;
slitting said first web into two narrow webs of substantially equal widths;
separating said two narrow webs into a spaced relation;
guiding a paper web between said two narrow webs; and
converging said two narrow webs and said paper web together in two directions
to form a three layer composite web with said paper web sandwiched between
said two
narrow webs.
20
30
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With the foregoing and other objects, advantages and features of the invention
that will become hereinafter apparent, the nature of the invention may be more
clearly
understood by reference to the following detailed description of the
invention, the
appended claims and to the several views illustrated in the drawings.
Brief Description of the Drawings
FIG. 1 is a perspective view of the apparatus of the invention for making a
carbonaceous fuel element;
FIG. 2 is a side elevation view of the dual bobbin unwinder apparatus of the
invention;
FIG. 3 is . a side elevation view of the splicing apparatus of the invention;
FIGS. 4-7 are schematic views illustrating the sequential steps for making a
splice of two glass webs in the splicing apparatus of FIG. 3;
FIG. 8 is a fragmentary top plan view of a splice made according to the
invention in the splicing apparatus of FIG. 3;
FIG. 9 is a fragmentary side elevation view of a splice made according to the
invention in the splicing apparatus of FIG. 3;
FIG. 10A is a side elevation view of the web reservoir of the invention;
FIG. lOB is a cross-sectional end view of the web reservoir of the invention
taken along line A-A of FIG, 10A;
FIG. 11 is a side elevation view of the apparatus of the invention for making
the composite glasslpaper web;
FIG. 12 is a perspective view showing the manner in which the apparatus of
FIG:11 forms the composite web structure; and
FIG. 13 is a cross-sectional view of the composite web taken along line 13-13
of FIG. 11.
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detailed Descrip~ior~ of the Invention
Referring now in detail to the drawings, FIG. 1 illustrates an overall
perspective view of the apparatus of the invention for making a carbonaceous
fuel
element for a smoking article which apparatus is designated generally by
reference
numeral 10. Apparatus 10 comprises six major components: an extruder 12 for
extruding a carbonaceous fuel rod, a dual bobbin unwinder 14 for unwinding
slit webs
of glass fiber mat material, a splicer apparatus 16 for semi-automatically
splicing
alternate webs of glass mat unwound from the dual bobbin unwinder, a web
reservoir
18 for accumulating web during the splicing operation, a composite web maker
20 and
a KDF filter maker 22 modified to form a carbonaceous fuel element. The
extruder 12
produces an extruded carbonaceous rod which is conveyed in a V-shaped groove
(not
shown) of a conveyor 24 that is disposed above the other components of the
apparatus
to the KDF filter maker 22 where it is used to form the carbonaceous fuel
element.
The dual bobbin unwinder 14 (FIG. 2) comprises a frame 26 for supporting first
and second bobbin chucks 28, 30, respectively. On each chuck there is
supported a
respective bobbin Bi, B2 wound with a glass fiber web, such as an Owen-Corning
C-
glass mat, which has been slit into ten or more web strips Wl and WZ each
having a
width of about 38 mm. Each bobbin chuck 28, 30 is rotated by means of a
respective
servo drive motor (not shown) which is mounted on respective first and second
carriages 32, 34 movable back and forth independently of one another and
transversely
with respect to the payout direction of the webs Wl, Wz.
The webs Wl, WZ are both aligned with a given path of travel of the web
through the apparatus 10. When one of the webs Wl or WZ is payed out from a
given
bobbin Bl or B2, the carriage 32, 34 supporting that bobbin is indexed
transversely by
conventional means (not shown) one web width (38 mm) so as to bring a next
adjacent
web Wl or WZ into alignment with the given web path. The bobbin chucks 28, 30
are
positively driven or rotated by the servo drive motors at a speed controlled
by a capstan
roller 17 (FIG. 1) located on the web path between the splicer apparatus 16
and the
web reservoir 18. The capstan roller 17 is, in turn, synchronized to the speed
of the
KDF filter maker 22. As the web WI or W~ is payed out, the bobbin chuck 28 or
30
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must be rotated at an increasing speed to maintain a constant web pay out
speed equal
to the capstan roller, speed.
Bobbin speed is controlled by means of first and second control dancers 36, 38
which engage a respective web Wl or WZ passing between guide roller pairs 40
and 42
(only one roller 42 shown in FIG. 2). Control dancers 36,38 comprise dancer
arms
44 which bear upon a respective web Wt or WZ by means of a slight
counterclockwise
torsion applied to the pivot axes 46 of the dancer arms 44. Assuming the web
Wl or
WZ is supplied to the KDF filter maker 22 at a constant speed by the capstan
roller 17,
it will be understood that as the web WI or WZ on the bobbin Bl or BZ is
depleted for
a given rotational speed of the bobbin, the dancer arm will begin to pivot
clockwise
about pivot axis 46. The angular movement of arm 44 is sensed by a sensor 48,
such
as an optical sensor or any other suitable sensor, and the output of the
sensor is used
to control the speed of the servo drive motors for the bobbin chucks 28, 30 so
as to
maintain a constant web speed equal to the capstan roller speed during payout
of the
web Wl or ~ , except during the splicing operation which will be described
hereinafter.
Sensors 50 aligned with the web being payed out from each bobbin detect when
the web has been unwound or depleted to a given diameter of the bobbin. When
that
diameter is reached, a pair of the sensors 50 interact along axis D (FIG. 2)
and
transmit a signal to capstan roller 17 to cause it to increase web speed
which, in turn,
will cause the dancer arm 44 to pivot clockwise thus sending a signal from
sensor 48
to cause the servo drive motor to increase rotational speed of the bobbin
associated
therewith. This increased web speed is above the speed of the KDF filter maker
so that
the web will now accumulate in the web reservoir 18 in preparation for the web
splicing operation to be described hereafter.
Rotation and payout of the glass webs dislodge glass fibers and glass dust
from
the preliminary slitting operation into the atmosphere surrounding the
bobbins. Such
fibers and dust are drawn into a plenum 52 disposed above the bobbins. The
plenum
52 is connected via pipes 54, 56 to an exhaust blower (not shown) which draws
off the
glass fibers and dust for collection and disposal.
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FIG. 3 illustrates the splicer apparatus 16 disposed between the capstan
roller
17 and the respective guide rollers 40, 42 of the dual bobbin unwinder 14. A
control
panel 58 for the apparatus 10 is located at the splicer apparatus 16 since an
operator is
required to be stationed at the splicer to thread the web from alternate
bobbins to the
splicer and to load the splicer with tape strips for making each splice. It
will be seen
that the web path P is the same for each of the webs Wi and W2 through the
splicer 16
and downstream thereof.
The operation of the splicer apparatus generates _a certain amount of glass
dust
and loose glass fibers. Advantageously, air suction hoses are placed at those
locations
on the splicer where such dust and fibers are generated. The hoses are
connected to
the exhaust blower via a pipe 55 (FIG. 2) for carrying away the dust and
fibers for
collection and disposal. Suction hoses may also be located at any other source
of glass
dust and fibers in the apparatus 10 and connected to a pipe leading to the
exhaust
blower.
Referring now to FIGS. 10A and lOB the web reservoir 18 comprises a narrow
rectangular compartment 60 located just downstream of the capstan rollers 17.
A
transparent plastic front panel or access door 62 is hinged to the front of
the
compartment by hinges 64. Should any kinks, twists or tangles occur in the
glass web
in the web reservoir, they can be visually detected by the operator, easily
accessed
through the door 62 and corrected or eliminated manually. The compartment 60
comprises a rear metal plate 66, side walls 68 and a bottom wall 70. A curved
metal
guide 72 is mounted to the walls of the compartment 60 and is shaped to
prevent to the
greatest extent possible disturbances such as kinks, twists and tangles from
occurring
in the web as it accumulates in the reservoir. A guide arm 74 is mounted to
the rear
wall 66 and the web Wl or WZ is guided from the capstan rollers 17 over the
arm 74.
The operation of the splicer apparatus 16 will now be described with reference
to FIGS. 2-7, particularly FIGS. 4-7. Splicer apparatus 16 comprises inlet web
guides
76, 77 and outlet web guides 78, 79 arranged on the upstream and downstream
sides
respectively of a splicing region. A fixed web spacer 80 is located between
guides 76,
77 to form a pair of inlet web guides. Upper and lower web clamps 81, 82 are
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arranged to clamp the webs Wi and WZ respectively in their respective web
guides 76,
80 and 77, 80 and a downstream web clamp 83 is arranged to clamp the web WI or
WZ
in the outlet web guide 78, 79 before it is delivered to the capstan rollers
17 and further
downstream. Upper and lower air jets 84, 85 are arranged in the inlet web
guides to
direct a jet of air in the upstream direction for the purpose of ejecting from
the splicer
the trailing end remnant of a web that has been completely unwound from its
bobbin.
A tape base 86 supports a lower strip of splicing tape Tl which is held in
place
by air suction holes (not shown) in the base 86. Tape clamp 87 supports an
upper strip
of splicing tape TZ also by air suction holes in the clamp surface and is
vertically
movable toward and away from the tape base 86. A retractable knife 88 is
movable
between the base 86 and clamp 87 to cut the web ends square for splicing. Web
sensors 89, 90 are positioned to sense the presence of the leading end of webs
Wl, W2,
respectively when a respective web end is positioned for splicing.
The tape base 86 and tape clamp 87 are also movable by mechanisms (not
shown) away from the path of travel of the web to facilitate placement of the
splicing
tape strips Tl, TZ on the base and clamp by the operator. For example, the
tape base
86 may be moved transversely with respect to the web path P (out of the paper
as
viewed in FIG. 4) so that tape strips T, may be easily placed adhesive side
out on the
upper surface 91 of the base 86. Tape clamp 87 may be pivoted about an axis
parallel
to web path P so that the lower surface 92 thereof is vertical and faces the
operator for
tape placement. Other ways of positioning the base 86 and clamp 87 for ease of
splicing tape placement will be apparent to those skilled in the art.
Assume that bobbin Bz has just commenced unwinding web WZ which passes
through the splicer 16, capstan rollers 17, web reservoir 18 to the composite
web
maker 20. The operator will move the tape base 86 and tape clamp 87 to their
tape
loading positions and place the tape strips Tl and Tz on surfaces 91 and 92
respectively
where the strips are held by air suction. The leading end of web Wl will be
passed
under roller 93 and into the space between web guide 76 and web spacer 80 and
moved
downstream until its presence is sensed by web end sensor 89. Sensor 89
activates
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upper web clamp 81 to hold the leading end of web Wl in position for splicing.
This
is the position of the splicer shown in FIG. 4.
When the sensors SO (FIG. 2) sense that bobbin Bz has been unwound to a
predetermined diameter, a signal is transmitted to the capstan rollers 17 to
increase web
speed. As capstan rollers 17 increase speed, the dancer arm 44 is pivoted
clockwise
which causes the servo drive motor to rotate bobbin Bz faster. This will cause
web WZ
to accumulate in web reservoir in preparation for splicing. At a predetermined
speed
of the bobbin B2 the servo drive motor stops rotating the bobbin Bz, web
clamps 82,
83 are activated to clamp web WZ in web guides 77, 80 and 78, 79 and knife 88
cuts
web W, and retracts from between the tape base 86 and tape clamp 87 (FIG. 5).
After the knife 88 is retracted, web clamp 82 is deactivated and air jet 85 is
operated to eject the.web end remnant of web WZ from the splicer 16 (FIG. 6).
Thereafter, tape clamp 87 is moved downwardly against tape base 86 to press
the
adhesive side of the tape strips Tl, TZ against the upper and lower web
surfaces adjacent
the trailing end of web WZ and the leading end of web WI to form the splice
(FIG. '~.
After the splice is formed, the tape clamp 87 and web clamps 81, 83 retract
and
capstan rollers 17 begin pulling the spliced glass web through the splicer.
During the
splicing operation, the KDF filter maker 22 and composite web maker 20 were
supplied
with web from the web reservoir 18 and thus used up most of the accumulated
web WZ
in the reservoir. Bobbin carriage 34 is next indexed the width of a web to
align the
~ next adjacent web on bobbin B2 with the web path P. The operator then loads
the
splicer with new tape strips Tl, TZ and threads the leading end of the next
web WZ into
web guide 77, 80 up to sensor 90 which activates web clamp 82 to position web
W2 for
the next splice which proceeds as generally described above in connection with
FIGS.
4-7, except that the web being payed out is web W, and the web clamped for
splicing
is web WZ.
The sensors 89, 90 are located slightly upstream of the cutting plane of knife
88 (FIG. 4) so that when the splicing tape strips Tl, TZ are applied to the
ends of the
webs Wl, W2, a gap G of about 1/8 inch to about 3/8 inch is formed between the
web
ends. Referring to FIGS. 8 and 9, the preferred splice structure is shown with
gap G
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between the ends of the webs Wl and WZ. The width of tapes Tt, TZ is
preferably less
than the width of the webs Wl, W2. The presence of gap G results in a much
stronger
and more reliable spliced joint between the webs W,, W2. If the web ends were
arranged to abut against one another, flexure of the joint as shown in phantom
lines in
S FIG. 9 could result in detachment or loosening of the adhesive bond between
tape TZ
and the ends of webs Wl and WZ.
FIGS. 11 and 12 illustrate the composite web maker or former 20 into which
the web Wl or WZ passes from the web reservoir 18. The full width (38 mm) web
travels over guide rollers 94, 95 to a web slitter 96 where the web is slit
longitudinally
by cutter 97 into two equal strips Wa, Wb each having a width of about 19 mm.
Webs
Wa and Wb are separated at slitter 96 along vertically spaced paths of travel
P ~ P zabout
respective sets of guide rollers 98, 99 and 100, 101. A bobbin B, of a tobacco
paper
web W~ is mounted on a bobbin chuck 102. The web W~ is pulled from the bobbin
B3
by the KDF filter maker at the same speed as the webs Wa, Wb. Web W~ passes
over
and about a plurality of conventional rollers 104, 106 and then vertically
upwardly to
a roller 108 positioned intermediate the paths Pl, P2 where it is transversly
aligned and
guided by guide 115 to a roller 110 along a path P3 substantially parallel to
paths PI, .
P2. Beginning at the rollers 98, 100, 108 and continuing to rollers 99, 101,
110, the
three webs Wa, Wb, W~ are directed into a transversely aligned, overlapping
relation
and are then caused to converge by rollers 112, 113, 114 into a three layer
composite
web W~ comprising tobacco paper web W~ sandwiched between glass webs W ~, and
W b
as shown in FIG. 13.
Web W~ passes downstream from composite web maker 20 to the KDF filter
maker 22 where it is wrapped about the carbonaceous fuel rod from the extruder
12 and
overwrapped with paper to form a continuous carbonaceous fuel element for use
in a
smoking article.
The apparatus 10 operates generally as follows: A carbonaceous rod is
continuously extruded from extruder 12 and is conveyed via a conveyor 24
directly to
the KDF filter maker 22 where it is combined with a composite glass/tobacco
paper
web and a paper overwrap to form a continuous carbonaceous fuel rod which is
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subsequently cut into individual fuel elements for use in making a smoking
article. The
composite glass/tobacco paper web W~ is also continuously formed in parallel
with the
carbonaceous rod and is supplied to the KDF filter maker 22 along with the
paper
overwrap .
The composite web W~ is continuously formed by unwinding from alternate
bobbins BI, Bz of a dual bobbin unwinder 14, webs W 1, W 2 of a given length
and semi-
automatically splicing the webs together in a splicer apparatus 16. Prior to
the splicing
operation, the unwinder 14 speeds up to accumulate an excess of web material
in a web
reservoir 18 so that when the webs are held stationary for splicing together,
the KDF
filter maker is supplied with sufficient web material so that production rate
is
maintained constant.
The glass webs Wl and Wz are twice the width of the finished composite web.
Thus, fewer slits are necessary on the web bobbins and the webs Wl and WZ can
withstand greater tensile forces without breakage or stretching. Moreover,
only one
dual bobbin unwinder is needed since the web is slit into two webs downstream
of the
splicer. If the webs were supplied at the width of the finished composite web,
two
unwinders and four bobbins would be needed to maintain a continuous process.
In the composite web maker 20, the web WI or WZ is slit into two equal webs
Wa, Wn and vertically separated by a roller system. A tobacco paper web W is
interposed between the webs Wa, Wb and sandwiched between them as the webs are
converged both laterally and vertically by the roller system into a three-
layer composite
web W~. Thereafter, the composite web W~ is fed to the KDF filter maker 22
where
it is wrapped about the carbonaceous rod and overwrapped with a paper overwrap
in
a conventional manner for use in a smoking article.
Although certain presently preferred embodiments of the present invention have
been specifically described herein, it will be apparent to those skilled in
the art to which
the invention pertains that variations and modifications of the various
embodiments
shown and described herein may be made without departing from the spirit and
scope
of the invention. Accordingly, it is intended that the invention be limited
only to the
extent required by the appended claims and the applicable rules of law.
