U.S. patent application number 10/500574 was filed with the patent office on 2005-02-10 for forming unit for producing sealed packages from a tube of sheet packaging material filled with a pourable food product.
Invention is credited to Borghi, Davide, Sabbadini, Davide.
Application Number | 20050028496 10/500574 |
Document ID | / |
Family ID | 8185819 |
Filed Date | 2005-02-10 |
United States Patent
Application |
20050028496 |
Kind Code |
A1 |
Sabbadini, Davide ; et
al. |
February 10, 2005 |
Forming unit for producing sealed packages from a tube of sheet
packaging material filled with a pourable food product
Abstract
There is described a forming unti (1) for producing sealed
packages (2) from a tube (3) of sheet packaging material fed along
a feed path (A) and filled with a pourable food product. The unit
(1) has jaw means (6, 6') acting cyclically on the tube (3) to grip
and seal it at equally spaced cross sections defining opposite
sealing bands (15) of the packages (2); interacting means (23; 16)
interacting with the tube (3) and fitted movably to the jaw means
(6, 6'); and actuating means (27; 40) for operating the interacting
means (23; 16) and mounted entirely on the jaw means (6, 6').
Inventors: |
Sabbadini, Davide; (Carpi,
IT) ; Borghi, Davide; (Modena, IT) |
Correspondence
Address: |
BURNS DOANE SWECKER & MATHIS L L P
POST OFFICE BOX 1404
ALEXANDRIA
VA
22313-1404
US
|
Family ID: |
8185819 |
Appl. No.: |
10/500574 |
Filed: |
July 1, 2004 |
PCT Filed: |
December 30, 2002 |
PCT NO: |
PCT/EP02/14798 |
Current U.S.
Class: |
53/548 |
Current CPC
Class: |
B29C 66/1122 20130101;
B65B 9/2042 20130101; B29C 65/7802 20130101; B29C 66/7234 20130101;
B29C 66/8246 20130101; B29C 66/72321 20130101; B29C 66/71 20130101;
B65B 9/20 20130101; B29C 65/368 20130101; B29C 66/71 20130101; B65B
51/30 20130101; B29C 65/3656 20130101; B29C 66/849 20130101; B29C
66/81457 20130101; B29C 66/8226 20130101; B29L 2031/7166 20130101;
B29C 66/8167 20130101; B65B 41/18 20130101; B29K 2023/06 20130101;
B29C 66/83543 20130101; B29C 66/4312 20130101; B29C 66/72328
20130101; B29C 2795/002 20130101 |
Class at
Publication: |
053/548 |
International
Class: |
B65B 009/12 |
Foreign Application Data
Date |
Code |
Application Number |
Jan 8, 2002 |
EP |
02425003.7 |
Claims
1. A forming unit for producing sealed packages from a tube of
sheet packaging material fed along a feed path and filled with a
pourable food product, said unit comprising jaw means acting
cyclically on said tube to grip and seal it at equally spaced cross
sections defining opposite sealing bands of said packages;
interacting means interacting with said tube and fitted movably to
said jaw means; and actuating means for operating said interacting
means; wherein said actuating means are mounted entirely on said
jaw means.
2. A unit as claimed in claim 1, wherein said jaw means comprise at
least two forming assemblies, each defined by a pair of jaws
cooperating cyclically with each other and with said tube.
3. A unit as claimed in claim 1, wherein said interacting means
comprise traction means for exerting pull on said tube of packaging
material to correct the travel of said tube along said feed
path.
4. A unit as claimed in claim 3, wherein said traction means
comprise two movable members carried by one of said jaws of each
said forming assembly and interacting on opposite sides with said
tube.
5. A unit as claimed in claim 4, wherein said movable members
comprise respective pins rotating with respect to the relative said
jaw; and respective tabs carried eccentrically by said pins.
6. A unit as claimed in claim 4, wherein, for each said one of said
jaws, said actuating means comprise a first control actuator, and
transmission means interposed between said first actuator and said
movable members.
7. A unit as claimed in claim 6, wherein each said first actuator
comprises a first output member movable in a direction crosswise to
said feed path of said tube and to the axes of said pins of the
relative said movable members; and in that said transmission means
comprise, for each said one of said jaws, a lever, which has a
connecting portion hinged to said first output member of the
relative said first actuator, and defines two fastening portions to
which are hinged respective arms for activating the relative said
movable members and carried eccentrically by the respective said
pins.
8. A unit as claimed in claim 1, wherein said interacting means
comprise box means enclosing portions of said tube of predetermined
shape and volume and eventually defining said packages.
9. A unit as claimed in claim 8, wherein, for each said forming
assembly, said box means comprise a pair of boxes connected movably
to the respective said jaws and cooperating with each other to
define a cavity of predetermined shape and volume and enclosing
said tube.
10. A unit as claimed in claim 9, wherein, for each said forming
assembly, said actuating means comprise push means activated
selectively to grip together the relative said boxes.
11. A unit as claimed in claim 10, wherein said push means
comprise, for each said jaw, a second control actuator having a
second output member movable in a direction crosswise to said feed
path of said tube; and a toggle mechanism, which extends crosswise
to the travel direction of said second output member, is interposed
between the relative said jaw and the relative said box, and is
activated by the second output member.
Description
TECHNICAL FIELD
[0001] The present invention relates to a forming unit for
producing sealed packages from a tube of sheet packaging material
filled with a pourable food product.
BACKGROUND ART
[0002] As is known, many pourable food products, such as fruit
juice, pasteurized or UHT (ultra-high-temperature processed) milk,
wine, tomato sauce, etc., are sold in packages made of sterilized
sheet packaging material.
[0003] A typical example of such a package is the
parallelepiped-shaped package for liquid or pourable food products
known as Tetra Brik Aseptic (registered trademark), which is formed
by folding and sealing a web of laminated packaging material.
[0004] The packaging material has a multilayer structure comprising
a layer of paper material covered on both sides with layers of
heat-seal plastic material, e.g. polyethylene; and, in the case of
aseptic packages for long-storage products such as UHT milk, the
packaging material also comprises a layer of oxygen-barrier
material defined, for example, by a sheet of aluminium, which is
superimposed on a layer of heat-seal plastic material, and is in
turn covered with another layer of heat-seal plastic material
eventually defining the inner face of the package contacting the
food product.
[0005] As is known, such packages are made on fully automatic
packaging machines, on which a continuous tube is formed from the
web-fed packaging material. More specifically, the web of packaging
material is unwound off a reel and fed through an aseptic chamber
on the packaging machine, in which it is sterilized, e.g. by
applying a chemical sterilizing agent, such as hydrogen peroxide,
which is later vaporized by heating and/or subjecting the packaging
material to radiation of appropriate wavelength and intensity; and
the web so sterilized is maintained in a closed sterile
environment, and is folded and sealed longitudinally into a
cylinder to form a continuous tube in known manner.
[0006] The tube of packaging material, which in other words forms
an extension of the aseptic chamber, is fed continuously in a
vertical direction, is filled with the sterilized or
sterile-processed food product, and is fed through a forming unit
for forming the individual packages.
[0007] The forming unit comprises two pairs of jaws acting
cyclically and successively on the tube of packaging material to
grip and heat seal it along equally spaced cross sections and so
form a continuous strip of pillow packages connected to one another
by respective transverse sealing bands, i.e. extending
perpendicularly to the traveling direction of the tube. The pillow
packages are separated by cutting the relative transverse sealing
bands, and are then fed to a folding station where they are folded
mechanically into the finished parallelepiped shape.
[0008] The tube portion gripped between each pair of jaws is heat
sealed by heating means carried by one of the jaws and for locally
melting the two layers of heat-seal plastic material gripped firmly
between the jaws.
[0009] When heat sealing is completed, a cutting member, carried by
one of the jaws and interacting with the tube of packaging
material, is activated to cut the tube along the centerline of the
transverse sealing band and so detach a pillow package from the
bottom end of the tube of packaging material. The bottom end is
therefore sealed transversely, and the jaws, on reaching the bottom
dead-center position, are opened to avoid interfering with the
above part of the tube. At the same time, the other pair of jaws,
operating in the same way, moves down from the top dead-center
position to repeat the gripping/forming, sealing and cutting
operations as described above.
[0010] One problem encountered on known forming units concerns the
so-called "decoration correction" system.
[0011] That is, the web of packaging material normally comprises a
series of equally spaced printed images or decorations on the
portions eventually forming the outer surfaces of the packages, so
that the web must be fed to the forming unit in such a manner that
forming, sealing and cutting of the packages are performed "in
register" with the succession of decorations. In actual use, since
the decorations are printed equally spaced, the position of each
with respect to the position of the jaws on the forming unit may
vary, firstly, as a result of varying deformation of the packaging
material by the mechanical pressure exerted on it by the jaws, and,
secondly, as a result of the pulsating pressure of the pourable
food product inside the tube of packaging material. A system for
position correcting the decoration is therefore required, since, on
a packaging machine operating at high output speed, even small
shifts in the position of the decorations with respect to the
theoretical register position, if not corrected in real time, may
increase with time, thus resulting in the production of
unacceptable packages which must be rejected.
[0012] On modern packaging machines, such a system comprises an
optical sensor for detecting the position of a bar code on each
package; and a control unit for comparing the detected position
with respect to a theoretical position.
[0013] On some commercial machines, each pair of jaws has a pair of
traction members for drawing the tube of packaging material, and
which are fitted movably to one of the jaws in each pair to form
triangular tabs at the top and bottom corners of the pillow
packages; and, on detecting a decoration position error, the
control unit adjusts the speed of the packaging material web feed
motor. If this correction is not sufficient, the traction members
are controlled to slightly increase or reduce pull on the packaging
material. On other machines, the control unit acts directly on the
traction members, with no possibility of adjusting the speed of the
packaging material web feed motor; and the operation is repeated
until the position of the decoration coincides with the theoretical
position.
[0014] More recently, solutions have been devised whereby the
position of the decorations on the packaging material is controlled
by adjusting the travel and timing of the pairs of jaws acting on
the tube.
[0015] As described, for example, in Italian Patent n. 1296062, the
traction members are operated by means of a continuous linear
actuating member, e.g. a pneumatic cylinder, which is fitted to the
supporting structure of the forming unit, is activated by the
control unit of the decoration correction system, and is connected
to the traction members by transmission means.
[0016] More specifically, in the case described, the transmission
means comprise an actuating rod, which is fitted movably to the jaw
fitted with the traction members, is fitted at one end with a
tappet member, and is connected at the opposite end to the traction
members by respective articulated arms. The tappet member is in
turn fitted to run along a cam profile, which is fitted adjustably
to the supporting structure of the forming unit, is connected to
the actuating member by a motion-conversion conversion assembly,
and is movable with respect to the supporting structure by the
actuating member.
[0017] In other words, operation of the traction members calls for
an extremely complex, heavy transmission to transfer motion from
the actuating member fitted to the fixed part of the forming unit,
to the traction members fitted to the movable jaws, and therefore
involves a large number of component parts on both the supporting
structure of the forming unit and the jaws, thus greatly increasing
the overall cost of the packaging machine, and the time taken to
assemble and disassemble the forming unit to perform any
maintenance work.
[0018] The complexity of known forming units is further compounded
by the jaws normally comprising, in addition to the traction
members, further movable members, such as so-called "volume boxes",
which mate to define the volume and shape of the pillow packages
being formed, and which call for dedicated actuating means.
DISCLOSURE OF INVENTION
[0019] It is an object of the present invention to provide a
forming unit for producing sealed packages from a tube of sheet
packaging material filled with a pourable food product, and
designed to eliminate the aforementioned drawbacks typically
associated with known units.
[0020] According to the present invention, there is provided a
forming unit for producing sealed packages from a tube of sheet
packaging material fed along a feed path and filled with a pourable
food product, said unit comprising jaw means acting cyclically on
said tube to grip and seal it at equally spaced cross sections
defining opposite sealing bands of said packages; interacting means
interacting with said tube and fitted movably to said jaw means;
and actuating means for operating said interacting means;
characterized in that said actuating means are mounted entirely on
said jaw means.
BRIEF DESCRIPTION OF DRAWINGS
[0021] A preferred, non-limiting embodiment of the present
invention will be described by way of example with reference to the
accompanying drawings, in which:
[0022] FIGS. 1 and 2 show respective front and side views, with
parts removed for clarity, of a forming unit, in accordance with
the present invention, for producing sealed packages from a tube of
sheet packaging material filled with a pourable food product;
[0023] FIG. 3 shows an exploded, rear-lateral view in perspective,
with parts removed for clarity, of a sealing jaw of the FIGS. 1 and
2 forming unit;
[0024] FIG. 4 shows a front-lateral view in perspective of the FIG.
3 jaw;
[0025] FIG. 5 shows a larger-scale rear view of a portion of the
FIG. 3 jaw;
[0026] FIG. 6 shows a rear-lateral view in perspective, with parts
removed for clarity, of a variation of the FIG. 3 sealing jaw.
BEST MODE FOR CARRYING OUT THE INVENTION
[0027] Number 1 in FIG. 1 indicates as a whole a forming unit for
producing sealed packages 2 from a tube 3 of sheet packaging
material having an axis A, filled with a pourable food product, and
fed along a vertical path P parallel to axis A.
[0028] More specifically, tube 3 is formed in known manner by
longitudinally folding and sealing a web of packaging material, and
is filled, upstream from unit 1, with the food product for
packaging.
[0029] The web of packaging material has a multilayer structure
(not shown), and conveniently comprises a layer of paper material
covered on both sides with layers of heat-seal plastic material,
e.g. polyethylene. In the case of aseptic packages for long-storage
products such as UHT milk, the packaging material also comprises a
layer of oxygen-barrier material defined, for example, by a sheet
of aluminium, which is superimposed on a layer of heat-seal plastic
material, and is in turn covered with another layer of heat-seal
plastic material eventually defining the inner face of packages 2
contacting the food product.
[0030] On the side eventually defining the outer surface of
packages 2, the web of packaging material has a succession of
graphics or decorations repeated at equally spaced intervals.
[0031] Unit 1 comprises a supporting structure 4 defining two
vertical guides 5, which are arranged symmetrically with respect to
a central vertical longitudinal plane M of unit 1 through axis A,
and the respective axes of which lie in a central vertical
transverse plane T of unit 1. Axis A therefore defines the
intersection of planes M and T.
[0032] Unit 1 comprises, in known manner, two forming assemblies 6,
6', which move vertically along respective guides 5, and interact
alternately with tube 3 of packaging material to grip and heat seal
cross sections of the tube.
[0033] Since assemblies 6, 6' are symmetrical with respect to plane
M, only one (assembly 6) is shown in detail in FIG. 2 and described
below. The corresponding parts of assemblies 6, 6' are indicated in
the drawings using the same reference numbers.
[0034] With reference to FIGS. 1 and 2, assembly 6 substantially
comprises a slide 7 running along respective guide 5; and two jaws
8a, 8b hinged at the bottom to slide 7 about respective horizontal
axes B, parallel to and symmetrical with respect to plane T, so as
to open and close substantially bookfashion.
[0035] The reciprocating movement of slides 7 and the
opening/closing movement of jaws 8a, 8b are controlled in known
manner (not described) by pairs of vertical rods (not shown) in
turn controlled by rotary cams or servomotors.
[0036] More specifically, each jaw 8a, 8b comprises a main control
body 10--substantially in the form of an appropriately ribbed,
quadrangular plate (FIGS. 1 and 2) extending along a work plane V
of jaw 8a, 8b containing respective axis B--which is hinged, close
to its bottom side, to slide 7, and has a control arm 11 projecting
from a face of body 10 on the opposite side to plane V, and
activated in known manner (not shown) by one of said vertical
rods.
[0037] Jaws 8a, 8b also comprise respective supporting arms 12a,
12b fixed to the top end of respective bodies 10, and which project
towards and beyond plane M, in a direction parallel to respective
axes B, and substantially along respective work planes V, so as to
be located on opposite sides of tube 3.
[0038] The projecting portions of arms 12a, 12b are fitted with
respective bar-shaped sealing members 13a, 13b (FIG. 2), which
interact with tube 3, and which may be defined, for example, by an
inductor for generating a current in the aluminium layer of the
packaging material and so melting the thermoplastic layer as a
consequence of the Joule effect, and by a contrasting pad providing
the necessary mechanical support to grip tube 3 to the required
pressure.
[0039] Jaws 8a, 8b are movable between a closed position, in which
respective sealing members 13a, 13b grip tube 3, and a fully-open
position.
[0040] At the transverse sealing step, tube 3 is heat sealed along
equally spaced cross sections to form respective sealing bands
15.
[0041] Over respective sealing members 13a, 13b, arms 12a, 12b of
jaws 8a, 8b support respective so-called "volume boxes" for
controlling the volume of packages 2, and which are shown in more
detail in FIG. 6.
[0042] Boxes 16 are hinged at the bottom to arms 12a, 12b of
respective jaws 8a, 8b about respective axes C parallel to axes B,
and are maintained in a predetermined position on arms 12a, 12b by
known elastic means not shown.
[0043] Boxes 16 have a C-shaped cross section open at the front,
and, following transverse sealing by members 13a, 13b, cooperate
with each other to define a cavity, of given shape and volume,
enclosing tube 3 into a rectangular-section configuration.
[0044] Each box 16 comprises a flat rear wall 17 facing arm 12a,
12b of relative jaw 8a, 8b and substantially parallel to relative
plane V; and two flat lateral walls 18 extending perpendicularly
from opposite lateral edges of rear wall 17.
[0045] This forming step produces pillow packages 2 having a main
portion 20 of the same shape and volume as the finished packages;
and transition portions 21 connecting main portion 20 to the
respective adjacent sealing bands 15, and which are defined
laterally by substantially triangular faces 22.
[0046] As shown in FIGS. 2, 3, 4 and 5, one (8a) of jaws 8a, 8b
comprises, in known manner, two movable traction members 23 for
controlling longitudinal feed of tube 3 through unit 1.
[0047] Movable members 23 are located, symmetrically with respect
to axis A, on either side of and adjacent to tube 3. More
specifically, movable members 23 comprise respective pins 24 fitted
in axially-fixed, rotary manner through respective holes formed
through arm 12a and having axes D, E perpendicular to plane V; and
respective tabs 26 carried eccentrically by pins 24 and which
interact with the packaging material of tube 3.
[0048] More specifically, tabs 26 project from respective front
ends of pins 24 facing tube 3, and therefore project from arm 12a
on the same side as and over relative sealing member 13a, and are
curved with their concavities facing, and taper in section towards
tube 3.
[0049] Movable members 23 are counter-rotated by an actuating
device 27 about respective axes D, E, i.e. so as to describe equal,
opposite angles and so move tabs 26 symmetrically with respect to
path P. Actuating device 27 is active at the forming step, so as to
cause tabs 26 to act on lateral faces 22 of transition portions 21
of pillow packages 2, and exert variable pull on tube 3 in the tube
feed direction to correct any error in the position of the
decorations on the packaging material.
[0050] More specifically, actuating device 27 is controlled by a
known control unit--not shown, by not forming part of the present
invention--which, by means of one or more optical sensors, detects
the actual position of the decorations on the packaging material
from which packages 2 are to be formed, compares it with a
theoretical reference position, and accordingly adjusts the pull to
be exerted by movable traction members 23. Alternatively, actuating
device 27 may operate movable members 23 between two predetermined
positions to simply form the individual packages 2.
[0051] According to an important characteristic of the present
invention, actuating device 27 is fitted to and supported entirely
by arm 12a of jaw 8a.
[0052] More specifically, actuating device 27 comprises a
continuous linear actuator 28, e.g. a pneumatic cylinder; and a
transmission mechanism 29 interposed between actuator 28 and pins
24 of movable members 23.
[0053] Actuator 28 comprises an outer jacket 30 fixed to arm 12a of
jaw 8a, adjacent to main body 10, and having an axis F parallel to
the maximum-extension direction of arm 12a; and a movable member 31
fitted to slide axially inside jacket 30, and having a rod 32
projecting from jacket 30 and connected to transmission mechanism
29.
[0054] As shown particularly in FIGS. 3 and 5, transmission
mechanism 29 comprises a contoured lever 33, which has an end
portion 34 hinged to a free end of rod 32 and defining two
fastening portions 35, 36, to which are hinged respective actuating
arms 37, 38 for activating movable members 23 and which are fitted
to and project radially from the rear ends of respective pins
24.
[0055] More specifically, lever 33 is substantially S-shaped,
extends along a plane parallel to plane V, and faces the opposite
side of arm 12a to that from which relative sealing member 13a
projects. In the example shown, one (35) of fastening portions 35,
36 is defined by an end portion of lever 33 opposite end portion
34, and the other fastening portion (36) is defined by an
intermediate portion of lever 33.
[0056] Actuating arms 37, 38 form different angles with lever 33,
so that linear displacement of rod 32 corresponds to opposite
rotations of movable members 23 about respective axes D, E.
[0057] In the FIG. 6 variation, in addition to actuating device 27,
jaw 8a of each forming assembly 6, 6' also supports a push device
40, which acts on relative box 16 to grip it against the
corresponding box 16 of jaw 8b. A similar push device is obviously
fitted in exactly the same way to jaw 8b of each forming assembly
6, 6' to activate relative box 16.
[0058] Push device 40 comprises a linear actuator 41, e.g. a
pneumatic cylinder, fitted to arm 12a of jaw 8a and parallel to
cylinder 28; and a toggle mechanism 42 interposed between actuator
41 and the rear of relative box 16.
[0059] More specifically, actuator 41 comprises an outer jacket 43
fixed to arm 12a of jaw 8a, adjacent to body 10, and having an axis
G parallel to axis F; and a movable member 44 fitted to slide
axially inside jacket 43, and having a rod 45 projecting from
jacket 43 and connected by its free end to toggle mechanism 42.
[0060] Toggle mechanism 42 comprises two levers 46, 48 extending
crosswise to rod 45 of movable member 44, and having adjacent ends
hinged to each other and to rod 45, and opposite ends hinged
respectively to rear wall 17 of relative box 16, and to arm 12a,
close to the side of arm 12a facing lever 33.
[0061] Rod 45 is movable between a forward position corresponding
to maximum extraction from jacket 43, and in which it maintains
levers 46, 48 substantially perpendicular to rear wall 17 of
relative box 16, so as to exert maximum pressure against box 16 of
the opposing jaw 8b, and a withdrawn position corresponding to
minimum extraction from jacket 43.
[0062] In actual use, jaws 8a, 8b of each forming assembly 6, 6'
close as the assembly moves down, so as to grip tube 3 with a
downward vertical component of motion equal to the traveling speed
of tube 3. More specifically, jaws 8a, 8b of each forming assembly
6, 6' are brought together to gradually deform tube 3 and "flatten"
it at a cross section or transverse band. At which point, sealing
members 13a, 13b seal the two superimposed portions of the
packaging material forming the flattened transverse band.
[0063] Once heat sealing is completed, boxes 16 of jaws 8a and 8b
are brought together frontwards to define a parallelepiped-shaped
cavity defining the volume of main portion 20 of package 2 being
formed.
[0064] Boxes 16 of opposing jaws 8a, 8b are pushed into contact
with each other in opposition to respective elastic means and by
activation of respective push devices 40. More specifically, the
movement of rod 45 of each actuator 41 opens levers 46 and 48 of
toggle mechanism 42 into a position in which they are substantially
aligned with each other, thus pushing relative box 16 against the
opposing box 16.
[0065] In the course of the above forming step, and in coordination
with jaws 8a, 8b, actuator 28 is operated to activate movable
members 23. More specifically, rod 32 is extracted along axis F
from jacket 30 (FIG. 5) to accordingly move lever 33; and, by means
of arms 37, 38, the movement of lever 33 rotates movable members 23
in opposite directions to draw tube 3 downwards.
[0066] Close to a bottom dead-center position in the downward
travel of each forming assembly 6, 6', jaws 8a, 8b open to release
tube 3, continue opening as they move upwards, and are fully opened
before reaching the top dead-center position; at which point, jaws
8a, 8b begin closing, and are fully closed by the time they start
moving downwards.
[0067] Obviously, the movements of the two forming assemblies 6, 6'
are offset by a half-cycle: forming assembly 6 moves up with jaws
8a, 8b open while forming assembly 6' moves down with jaws 8a, 8b
closed, so as not to interfere with each other.
[0068] The advantages of unit 1 in accordance with the teachings of
the present invention will be clear from the foregoing
description.
[0069] In particular, by fitting actuating device 27 of movable
members 23, and possibly also push devices 40 of boxes 16,
integrally and directly to relative jaws 8a, 8b, the number of
component parts of forming assemblies 6, 6' is reduced
considerably, thus simplifying the assemblies, reducing the cost
and overall weight of unit 1, and so enabling unit 1 to be
assembled and disassembled faster for any maintenance work.
[0070] Clearly, changes may be made to unit 1 as described herein
without, however, departing from the scope of the accompanying
Claims.
[0071] In particular, unit 1 may comprise two sets of jaws 8a and
8b, which form part of respective chain conveyors, in turn defining
respective endless jaw feed paths, extend on opposite sides of the
feed path of tube 3, and cooperate cyclically with each other in
pairs. In which case, each forming assembly 6, 6' would be defined
by a jaw on one of the two conveyors, and by an opposing jaw on the
other conveyor.
* * * * *