This invention relates to an apparatus and method
for opening flattened bags.
Packaging machines often incorporate a bag making
section in which a web of a sealable material, which is
normally pre-printed with a repeating pattern giving the
advertising copy and product information that is to
appear on each bag, is formed into a tube by sealing
together edge opposite portions of the web and then
individual bag lengths with a transverse bottom fin seal
are severed from the tube. It is then necessary to open
out the flattened bag lengths so that a desired amount of
the desired product, for example a comminuted product
such as roasted and ground coffee, can be inserted into
the bag prior to sealing to form the finished package.
In some cases it may be desirable for the package to
be sold as an evacuated package whereas under other
circumstances it may be desired to sell a gas flushed
package. To enable these aims to be achieved the
packaging machine may incorporate an evacuation section,
with, optionally, a gas bleed-back arrangement.
It is important that the bag shall be opened
reliably since otherwise valuable product may be spilled
if the feed mechanism for filling of the bags attempts to
fill a bag that has not been properly opened. It is also
important that bag opening shall be effected quickly if
the high operating speeds, typically 200 bags per minute
or higher, that are now demanded in the art are to be
achieved.
GB-A-1003768 describes an apparatus for the packing
of solid or liquid materials in sealable bags or sachets.
This is a hand operated machine with a carriage movable
along a pathway and supporting a jig adapted to receive a
bag. The jig has double walls, the inner one of which is
permeable and the space between the double walls is
connected to a vacuum for opening the bag under the
influence of the vacuum. A suction cup attached to a
tubular arm is used to transfer a bag from a magazine to
the jig. After filling with biscuits or solid, granular
or liquid material the operator operates a lever which
folds over flaps at the upper end of the jig to fold over
the top of the bag, whereupon the top of the bag is
sealed. The sealed bag can then be removed from the jig,
one way of achieving this being by providing a
retractable bottom to the jig.
In WO-A-88/03892 there is disclosed a device for
compressing a compressible material packaged in an air-impermeable
casing such as a plastics sack. This has an
outer container in which an intermediate bag of air-impermeable
material is placed, the bottom of this
intermediate bag being anchored to the bottom of the
outer container. The sack with the material to be
compressed is placed in the intermediate bag and then air
is supplied to the space between the intermediate bag and
the outer container in order to compress the sack and its
contents.
An apparatus for spreading open flattened bags is
taught in US-A-5279095. This has a pair of air pervious
endless belts each with a working face and an opposite,
reverse face, with the working faces of the two belts
diverging from one another at an acute angle in a bag
conveying direction. The working faces run over
respective vacuum boxes so that a flattened bag
introduced into the nip between the belts with its top to
one side of the belts and with its bottom seal to the
other side of the belts is opened out as the bag moves
along between the diverging working faces of the belts.
Such an arrangement results, however, in quite high
energy consumption because of the use of vacuum boxes.
It is accordingly an object of the invention to
provide an apparatus for opening bags reliably and
speedily and with low energy consumption. It is a further
object of the invention to provide a method of opening
flattened bags at high speed, typically at speeds in
excess of 200 bags per minute, with great reliability,
and with a minimal energy consumption. An additional
object of the invention is to provide an apparatus for
opening flattened bags at high speed which obviates the
risk of damage to the bags during the bag opening step
and which enables packages of well defined shape to be
produced upon filling, sealing and evacuating the opened
bags.
According to the invention there is provided a
method of opening a flattened bag comprising the steps
of:
(a) providing a support container for a bag to be
opened, said container defining a partially enclosed
chamber with an open end; (b) introducing a flattened bag into the container, said
bag having an openable end and a closed end and being
positioned in the container with its closed end in said
chamber and its openable end extending towards or through
the open end of the chamber; and (c) applying suction to evacuate the chamber at spaced
regions in said chamber corresponding to peripheral
regions of the closed end of said bag, thereby to cause
the bag to open and to conform to the internal shape of
the chamber.
The invention further provides an apparatus for
opening a flattened bag comprising:
a support container for a bag to be opened, said
container defining a partially enclosed chamber with an
open end; means for introducing a flattened bag into the
container, the bag having an openable end and a closed
end, so as to position the flattened bag in the container
with its closed end in the chamber and with its openable
end extending towards or through the open end of the
chamber; and means for applying suction to the chamber so as
evacuate the chamber at spaced regions in said chamber
corresponding to peripheral regions of the closed end of
the bag, thereby to cause the bag to open and conform to
the internal shape of the chamber.
Preferably the chamber is constructed so as to have
a base substantially opposite said open end and at least
two side walls extending from the base towards said open
end, and is arranged so that suction can be applied from
narrow regions adjacent the transitions between said base
and said side walls. It is also preferred that the
container shall comprise first and second separable parts
laterally separable one from another, said first and
second separable parts including bottom wall means and
side wall mean, the bottom wall means cooperating in the
closed condition of the open topped support container to
form a bottom wall for the support container and the side
wall means of the first and second separable parts
cooperating in the closed condition of the support
container to form side walls for the support container;
in this case the flattened bag can be introduced into the
container by steps comprising:
opening the support container to admit a flattened
bag by separating the separable parts laterally; introducing the flattened bag between the first and
second separable parts; and closing the support container by bringing the first
and second separable parts together.
In a preferred method of the invention flattened bag
has a front, a back, and a transverse bottom seal and a
portion of the flattened bag is trapped between bottom
portions of the first and second separable parts of the
container as the separable parts close. In one
arrangement the container includes opposed portions which
are capable of gripping a portion of the flattened bag to
locate the flattened bag in the container in its closed
condition.
Said opposed portions may comprise a fixed portion
on one of the separable parts and a pivotable portion
pivotally mounted on said one of the separable parts so
as to be pivotable between a closed condition in which
said fixed and pivotable portions cooperate to grip said
portion of said flattened bag and an open position in
which said fixed portion and said pivotable portion are
spaced one from another to allow the flattened bag to
enter the container. Preferably the pivotable portion is
biased towards its open position. It can also be
arranged that the pivotable portion engages a bottom wall
portion of the other separable part which moves it
towards its closed position as the two separable parts
close to support said flattened bag.
In one arrangement the second separable part of the
container is pivotally linked to the first separable part
thereof by means of a parallelogram linkage and lateral
separation of the separable parts occurs by virtue of the
second separable part swinging laterally outwardly and
downwardly away from the first separable part.
In the container the bottom wall means are each
associated with a plenum chamber connected to respective
vacuum connection means and communicating with the
chamber around the flattened bag by means of passageways
adjacent the side wall means of the separable parts and
evacuation of the plenum chambers is effected through the
vacuum connection means thereby to evacuate the chamber
around the flattened bag and to open the flattened bag.
The bottom wall means can be arranged so as to separate
along a first substantially vertical longitudinal plane
while the side wall means of the second separable part is
arranged to separate from the side wall means of the
first separable part at at least one longitudinal end of
the support container along a vertical longitudinal plane
that is laterally offset from the first substantially
vertical longitudinal plane. Furthermore the bottom wall
means can be arranged to separate along a first
substantially vertical longitudinal plane while the side
wall means of the second separable part can be arranged
to separate from the side wall means of the first
separable part at one longitudinal end of the support
container along a second vertical longitudinal plane that
is laterally offset from the first substantially vertical
longitudinal plane and at the other longitudinal end of
the support container along a third longitudinal plane
that is laterally offset to the other side of the first
substantially vertical plane from the second
substantially vertical plane.
A preferred method further includes the step of
locking the support container closed after entry of a
flattened bag therein and before evacuation of the
chamber surrounding the flattened bag.
The method may further include:
moving the open topped support container in open
condition at a first predetermined substantially constant
speed along a path in a conveying direction through a bag
loading station; moving the flattened bag along a path in the same
direction through the bag loading station at a second
predetermined speed which is greater than the first
predetermined speed and between the two separable parts
of the support container; slowing the flattened bag as it enters the open
support container to the first predetermined speed; closing the support container by bringing the
separable parts together; and evacuating the chamber surrounding the flattened
bag.
If the flattened bag has a transverse bottom seal
and then the separable parts of the container are
arranged so that on closure with a flattened bag between
them the transverse bottom seal is trapped between bottom
portions of the separable parts.
In a particularly preferred arrangement the bottom
wall means of one of the separable parts includes a
plenum chamber communicating with the chamber around the
flattened bag and connected to a vacuum connection pipe
carrying a bellows connector, the bottom wall means of
the other separable part includes a plenum chamber
connected to a vacuum connection pipe carrying a bellows
connector, a vacuum box is mounted adjacent the path of
travel of the container, the vacuum box having a
operating face with one or more orifices which is
disposed substantially parallel to the path of travel of
the container, and a flexible belt having apertures
spaced along its length passes across the operating face
of the vacuum box, the spacing of the apertures and the
timing of the belt being arranged so that, as the
container with a bag therein passes the vacuum box, the
bellows connectors can communicate with the vacuum box
thereby to evacuate the plenum chambers and the chamber
around the flattened bag so as to open the flattened bag.
It is particularly preferred for the support
container to have a substantially parallelepipedal
interior shape in its closed condition.
The flattened bag will typically have a longitudinal
seal formed by sealing together opposite side edges of a
web of a sealable material and will also have a gusseted
bottom. Such gussets in the flattened bag may be defined
in part by diagonal seals. Preferably the flattened bag
is pre-creased along lines substantially parallel to the
closed end of the bag corresponding to the top and bottom
edges of the package, particularly when the package is a
substantially parallelepipedal package.
It will normally be preferred for the container to
be arranged to be moved along a predetermined path with
the flattened bag disposed edgewise to the direction of
movement of the container; in this case first and second
top closure members can be disposed above the
predetermined path so as to lie adjacent to the open end
of the container and form a top cover for the chamber.
These first and second juxtaposed members can be
laterally spaced one from another by a distance of from
about 2 mm to about 7 mm, e.g. from about 4 mm to about 6
mm.
In one form of apparatus there is further provided:
means for moving the container in open condition at
a first predetermined substantially constant speed along
a path in a conveying direction through a bag loading
station; means for moving the flattened bag along a path in
the same direction through the bag loading station at a
second predetermined speed which is greater than the
first predetermined speed and between the two separable
parts of the support container; means for slowing the flattened bag as it enters the
open support container to the first predetermined speed;
and means for closing the support container by bringing
the separable parts together.
In order that the invention may be clearly
understood and readily carried into effect two preferred
forms of bag opening and support apparatus constructed in
accordance with the present invention will now be
described, by way of example only, with reference to the
accompanying drawings, wherein:-
Figure 1 is a perspective view of part of a
packaging machine for making evacuated packages each
comprising a sealed, evacuated bag containing a charge of
a comminuted material, such as roasted and ground coffee; Figure 2 is a perspective view on an enlarged scale
of one of the bag containers of the machine of Figure 1,
with the container in its open condition; Figure 3 is a similar view to that of Figure 2
showing the bag container in its closed condition; Figure 4 is a front view of one of the bag
containers removed from the machine of Figure 1; Figure 5 is a left side view, partly in section, of
the bag container of Figure 4; Figure 6 is a top plan view, partly in section, of
the bag container of Figures 4 and 5; Figure 7 is a detail view of part of one of the
carriages of the machine of Figures 1 to 6; Figure 8 is a perspective view of a device for
delivering flattened bags to the machine of Figures 1 to
6; Figures 9 and 10 are front views of the device of
Figure 8 illustrating its mode of operation; Figure 11 is a further front view of the device of
Figures 8 to 10 showing the cam surfaces for controlling
the attitude of the bag-holding clips; Figure 12 is a vertical section of a modified form
of bag container in closed condition; and Figure 13 is a similar vertical section through the
bag container of Figure 12 in open condition.
Referring to Figure 1, part of a packaging machine 1
for making evacuated packages, for example evacuated
sealed bags containing roasted and ground coffee is
depicted. This has an endless chain 2 (only part of
which is shown) which passes between and around two
carousels (not shown) arranged one at each end of the
machine 1. The direction of travel of endless chain 2 is
shown in each of Figures 1 to 3 by arrows A. Endless
chain 2 is used to convey containers 3 for bags 4 around
the machine 1 to and from the portion of the machine 1
which is shown in Figure 1 and which is the portion of
machine 1 in which flat preformed bags 4' are inserted
into the containers 3 and opened out. Thus Figure 1
shows at its right hand side a flat bag 4' about to be
inserted into a container 3 and at its left hand side a
fully opened bag 4.
From the portion of the machine 1 illustrated in
Figure 1 the opened bags 4 are conveyed in the direction
of the arrow A to a first carousel at the left hand end
of the machine (as illustrated) where the containers 3
and bags 4 are individually tared, then part filled with
a first dose of roasted and ground coffee, re-weighed,
and topped up to a desired weight with a second dose of
the roasted and ground coffee. The containers 3 with
their filled bags 4 then travel back to the right hand
end of the machine 1 along a reverse path behind the
illustrated part of the machine 1 in the opposite
direction to arrow A and pass around the second carousel
which is at the right hand end of the machine 1, that is
to say the right hand end as illustrated. On this second
carousel the filled bags 4 are evacuated and sealed or
are evacuated, gas flushed (with, for example, carbon
dioxide or nitrogen) and sealed. A small amount of a
desirable coffee aroma fraction may be bled into the
evacuated filled bags 4 before the sealing step in order
to enhance the aroma when the sealed package is first
opened. In passage along the reverse path from the first
carousel to the second carousel the bags 4 and their
contents may be tamped by, for example, a brief period of
vertical vibration, in order to settle the contents of
the bags 4 and facilitate formation of a neat
parallelepipedal package.
As can better be seen from Figure 2, endless chain 2
consists of links 5 joined one to another with carriages
6 attached to appropriate links 5 at regular intervals.
Carriages 6 are arranged to run on a pair of
substantially parallel level tracks (not shown in Figures
1 to 3) on rollers 7. A guide roller 8 arranged to
rotate about a vertical axis is mounted on each carriage
6 and runs in a guide track (also not shown in Figures 1
to 3) mounted where necessary along the runs of the
endless chain 2 and on each carousel above the carriages
6 so as to assist in preventing carriages 6 from tipping.
A pair of similar guide rollers (which again are not
shown in Figures 1 to 3) which are also arranged to
rotate about a vertical axis are provided on the
underside of each carriage 6. These further rollers run
in a corresponding guide track under the endless chain 2
located between the level tracks for rollers 7; this
further guide track is not shown in Figures 1 to 3.
Each carriage 6 also carries a vertical flanged
member 9 which is slidably received in a bracket 10
mounted on the rear of carriage 6. Member 9 can be
raised and lowered at appropriate moments in the
operating cycle relative to its corresponding carriage 6
by means of a roller 11 which, at the appropriate moment
or moments in the operating cycle of the machine 1, runs
up a stationary ramp surface (not shown) as it is carried
around the machine 1 by the endless chain 2 in order to
raise member 9 and the container 3 that it carries and
then runs down a corresponding ramp surface (also not
shown) to lower it again.
As can be seen from Figure 2, member 9 carries at
its upper end a mounting plate 12 for its associated
container 3. Mounting plate 12 is provided on its rear
face with three studs 13 with enlarged heads (see Figure
5, which shows only one of the studs 13). Studs 13
engage in keyways 14 (see Figure 4) in a backing plate 15
on the front of container 3. This arrangement allows for
container 3 to be released temporarily from its
associated member 9 at the appropriate moment in the
operating cycle, specifically for taring and weighing
purposes. A crank arm 16 pivotally mounted on a pivot
pin 17 carries an operating roller 18 and a locking
roller 19 which engages in slots 20, 21 formed in
mounting plate 12 and backing plate 15 respectively to
lock container 3 in place on member 9. A spring 22 is
attached at one end to crank arm 16 and at its other end
to a bolt 23 on mounting plate 12 and biases crank arm 16
towards its locked position, as shown in Figure 3.
Operating roller 18 is arranged to bear against a
stationary cam track (not shown) which is shaped so as to
move roller 18 to its unlocked position, shown in Figure
2, at the appropriate point in the operating cycle of
machine 1, as the container 3 is carried along by chain
2, and then to move it back to its locked position again.
Each container 3 has interior surfaces which define
a substantially parallelepipedal shape. It is split
vertically into two halves 24, 25. The rear half 24 of
container 3 is connected to the front half 25 thereof by
a parallelogram linkage formed by pivoted arms 26, 27
(see Figure 5) at its left side and by a single pivoted
arm 28 at its right side. In moving from its closed
position, shown in Figure 3, to its open position, shown
in Figure 2, rear half 24 swings downward and rearward
away from front half 25. Container 3 is held locked in
its closed position by means of locking levers 29, 30
mounted one at each end of container 3 which engage
respectively with pins 31, 32 on front half 25. Levers
29, 30 are biased towards their locking positions by
means of respective springs 33, 34. Locking lever 29
pivots about pin 35 and carries a roller 36 which engages
with a stationary cam track (not shown) when it is
desired for container 3 to open. Locking lever 30 pivots
about pin 37 and carries a roller 38 which engages with a
corresponding stationary cam track (not shown), which
runs parallel to the corresponding cam track for roller
35, to open container 3 at the appropriate point along
its path. Roller 38' (see Figure 5) which is carried by
rear half 24 is arranged to cooperate with a
corresponding cam track (not shown) to urge rear half 24
back to its closed condition at a point further along the
path of container 3 from that at which container 3 is
caused to open.
Reference numerals 39, 40, 41, and 42 indicate pivot
pins for arms 26, 27, while reference numerals 43 and 44
indicate pivot pins for arm 28.
As can be seen from Figure 6, the two halves 24, 25
of container 3 are somewhat asymmetrical so that the
plane of separation 45 along which the two halves 24, 25
separate at the right hand end of container 3 is offset
to one side of the centre line L-L while the plane 46
along which the two halves 24, 25 separate at the left
hand end of the container 3 is offset to the other side
of centre line L-L. However, the two halves 24, 25
separate at the base of the container 3 along the centre
line L-L. The walls 24a, 24b, and 24c and base 24d
together define approximately half of a parallelepiped,
the remaining portion of which is defined by the walls
25a, 25b and 25c and the base 25d of half 25.
The base of the container 3 is provided with plenum
chambers 47, 48 arranged one in each half 24 or 25.
These plenum chambers 47, 48 are covered, except along
the edges adjacent the internal walls of the respective
half 24 or 25, with respective cover plates 49, 50; in
Figure 6 the halves of these cover plates 49 and 50
towards the top of the Figure have been cut away to show
the plenum chambers 47 and 48. Thus there are narrow
slit-shaped apertures 51, 52 between the edges of cover
plates 49, 50 and the internal walls of container 3 and
larger substantially triangular apertures 53, 54 in the
corners of the bottom of container 3. As can be seen
from Figure 6, the corner of cover plate 50 can be cut
away at 55. The bottom of container 3 can be made of
magnetic material so that it will sit firmly on a load
cell (not shown) on the first carousel during taring and
weighing, at which time container 3 will have been
released from member 9 by moving crank arm 16 to its
unlocked position and lowering member 9 to cause studs 13
to move into the larger area parts of keyways 14. Roller
56 (see Figures 2 and 3) is arranged to cooperate with an
appropriately positioned ramp surface (not shown) to
impart a vertical vibratory movement to container 3 to
assist in tamping of the charge of coffee or other
comminuted material after the necessary weighing action
has taken place.
The half 24 is provided with a vacuum connection
pipe 57 with a flexible bellows connector 58 at its end;
this vacuum connection pipe 57 leads to plenum chamber
47. A further vacuum connection pipe 59 with a further
flexible bellows connector 60 is provided on half 25.
This further vacuum connection pipe 59 is connected to
plenum chamber 48.
Above the path of travel of containers 3 there are
mounted two guide members 61, 62 (see Figure 1); these
are spaced very closely above the tops of containers 3
but are laterally spaced one from another by about 5 to
10 mm so that a near air tight enclosure is formed by
each container 3 and the guide members 61, 62 as the
container 3 passes under guide members 61, 62. In the
region below guide members 61, 62 there is mounted a
vacuum box (not shown) across whose rear perforated
operating face passes an endless belt (also not shown)
which moves in synchronism with chain 2 and is provided
with apertures arranged so as to marry up with bellows
connectors 58, 60 as each container 3 comes past the
vacuum box. The rear operating face of this vacuum box
is perforated so that a vacuum can be drawn through
bellows connectors 58, 60 as each container 3 passes
behind and in close proximity to the vacuum box in
synchronism with the apertured endless belt.
As can be seen from Figure 1, a flattened bag 4',
which has a bottom fin seal 63, is suspended vertically
from a spring loaded clip 64 of clothes peg construction
for movement in the direction of arrow A. Each bag (see
flattened bag 4'' in Figure 1) is formed with side gussets
65, 66. Also the bottom end of each bag (see flattened
bag 4') has diagonal seals 67, 68. In addition the bag
4' has been horizontally pre-creased, as indicated at 63'
and 63'', at positions corresponding to where the top and
bottom edges will be in the evacuated filled package.
These side gussets, horizontal pre-creases and diagonal
seals assist in eventual formation of a neat
parallelepipedal package.
Figure 7 shows a detail of a carriage 6 and the
track 69 on which this runs. Also visible is the roller
70 (to which reference has been made above) mounted
underneath carriage 6. This runs in a groove 71 in track
69. Roller 8 runs in a corresponding groove 72 above the
carriage 6; here it is illustrated as being in the
underside of one of the carousels 73.
Figures 8 to 11 illustrate a device 74 for feeding
the flattened bag 4' to the container 3, which is in open
condition, at the right hand end of the part of the
machine 1 shown in Figure 1 so as to feed the flattened
bag 4' along a path which converges with that of the
container 3. Device 74 is also designed so as to impart
the desired variation in speed of movement of the clip
64. Device 74 comprises an endless belt 75 which is
driven in a clockwise direction around four rollers 76,
77, 78, and 79 which are located at the corners of a
frame in the shape of a floppy parallelogram formed by
members 80, 81, 82, and 83. These are pivoted one to
another by means of fixed pivots 84, 85 and by swinging
pivots 86, 87. A cross member 88 is pivoted to the mid
points of members 81, 83 on pivots 89, 90 and carries a
pair of cam follower rollers 91, 92 which engage with the
rim 93 of an elliptical cam wheel 94 which is mounted on
axle 95. (For the sake of clarity cam wheel 94 is
omitted from Figures 9 and 10). As cam wheel 94 is
rotated so cam follower rollers 91, 92 follow its rim 93
and move cross member 88 from side to side which in turn
causes the parallelogram linkage 80, 81, 82, 83 to swing
from side to side. The extremes of this swinging
movement are represented by Figures 9 and 10
respectively.
Belt 75 carries a number of clips 64 which are
similar in construction to spring loaded clothes pegs.
Clips 64 are each pivotally mounted on a shaft that
passes through a respective carrier 96. A spring loaded
push rod (not shown) extends through carrier 96. One end
of this push rod bears against one end of the rear
movable arm of peg 64 and the other end projects from the
rear of carrier 96. Pressure upon the rearward end of
the push rod causes clip 64 to open. Carrier 96 is also
provided with rollers 97 which bear on the edge of the
parallelogram linkage 80, 81, 82, 83 as the belt 75 moves
around it. The other end of the shaft on which clip 64
is mounted carries a crank arm 98 with a roller 99. This
roller 99 engages with a cam track 100 as it passes
around the bottom right hand corner of the parallelogram
linkage. This causes the clip 64 to pivot through 90°
until it extends horizontally. As it passes around the
bottom left hand corner of the parallelogram linkage so
roller 99 engages with a further cam surface 101 (see
Figure 11) which serves to rotate clip 64 through 90°
again so that when it comes round the top left hand
corner of the parallelogram linkage the clip 64 is again
vertical.
In operation of the illustrated machine 1, the
endless chain 2 is driven at a constant speed in the
direction of arrow A. A flattened bag 4', which has a
bottom fin seal 63, is suspended vertically from a clip
64 which is also moved in the direction of arrow A but
somewhat faster than endless belt 2 so that it can
overtake the containers 3. As can be seen from Figure 1
the container 3 at the right hand end of the illustrated
part of the machine 1 is open, the rollers 36 and 38
having been forced downwards by engagement with their
respective associated ramp surfaces (not shown). As the
flattened bag 4' enters the open container 3 along its
centre line L-L, the speed of clip 64 is reduced to match
the speed of endless chain 2. Thus the flattened bag 4'
and the open container 3 are now moving in synchronism.
Next the open container 3 closes by allowing rollers 36,
38 to come off their ramp surface and roller 38' to
engage with its corresponding ramp surface and by letting
locking levers 29 and 30 return under the influence of
springs 33 and 34 to their locked positions in which they
engage pins 31 and 32 respectively. The bag 4' is
positioned at such a height in relation to the half 25 of
the open container 3 that, as the container 3 closes, the
bottom fin seal 63 is trapped between the bottom edges of
the two halves 24 and 25. Because the container 3 splits
into two asymmetric halves 24 and 25 it is impossible for
flattened bag 4' to overshoot the open container 3 since
its leading vertical edge will hit first the inner face
of the left hand wall of the open container 3.
Immediately upon closure of container 3, clip 64 which is
attached to an endless belt (not shown) opens so as to
release flattened bag 4' and then travels on to pick up a
new flattened bag 4'. Opening of clip 64 is effected by
means of a fixed ramp surface (not shown) mounted behind
the path of clip 64 against which the rear end of its
spring loaded push rod bears so as to move the push rod
forward against its spring to open clip 64. As can be
seen best from the second flattened bag from the right
hand end of Figure 1, i.e. the flattened bag 4'', is
formed with side gussets 65, 66. Also the bottom end of
each flattened bag 4' has diagonal seals 67, 68. These
side gussets and diagonal seals assist in eventual
formation of a neat parallelepipedal package.
The now closed container 3, with a flattened bag
held firmly between the bottom edges of the two halves
24, 25 moves on under guide members 61, 62. Once the
container 3 is fully under guide members 61, 62, flexible
bellows connectors 58, 60 pass in front of a vacuum box
(not shown) so as to draw a vacuum, via pipes 57 and 59,
in the plenum chambers 47 and 48 respectively and hence
via slits 51, 52 and triangular apertures 53, 54 in the
main body of container 3. Because the top of container 3
is at this point nearly closed by the guide members 61
and 62, except for a narrow gap between them, air cannot
readily enter container 3 except by entering the
flattened bag positioned therein. As a result, the bag
opens very quickly and is drawn to conform snugly to the
inside shape of container 3. As the container 3 emerges
from under the left hand end of the guide members 61, 62
so the material of the bag tends to open it further as
shown at the left hand end of Figure 1.
The gap between guide members 61 and 62 should not
be so wide, on the one hand, that an effective vacuum
cannot be drawn quickly and without use of excessive
power within container 3 and not so narrow, on the other
hand, that the top of the bag cannot slide down somewhat
into container 3 to allow full opening of the bag to
occur. A lateral gap of about 5 mm has been found
suitable for bags made from a printed laminate 100 µm
thick consisting of a layer of polyethylene
terephthalate, a layer of low density polyethylene, and a
layer of peelable polyethylene, with the peelable layer
on the inside of the bag. Such a bag can be used for
packaging, for example, 500 g of roasted and ground
coffee.
Turning now to Figures 8 to 11, device 74 is
positioned below the path of movement of flattened bags
4' as they emerge from a bag forming machine bottom end
first. The direction of movement of the bags 4' is
indicated by arrow B in Figures 8 to 10; arrow A in
Figures 8 to 10 corresponds to arrow A of Figures 1 to 3.
As the clip comes around the top left hand corner of the
parallelogram linkage, its push rod bears against a ramp
surface (not shown) which forces it forward so that clip
64 is opened. The speed of travel of belt 75 is matched
to that of the flattened bags 4' as they emerge from the
bag forming machine pass in the direction of arrow B,
each with its transverse fin seal at its leading end.
The timing of the device 74 is so adjusted that, as each
clip 64 attains a vertical attitude after passing around
roller 76, it receives a flattened bag 4' (as shown in
Figure 9). Clip 64 then closes as the rear end of its
push rod comes off its cooperating ramp surface and
carries flattened bag 4' along with it as it continues to
move towards roller 77.
In order that the overall size of the packaging
machine can be reduced the spacing between adjacent
containers 3 along chain 2 is less than the height of a
bag 4', for example approximately one half the height of
a bag 4'. Since the speed of movement of the flattened
bags 4' as they emerge lengthwise from the bag forming
machine is greater than the speed of endless chain 2, it
is necessary to slow the bag 4' as it is inserted into
the appropriate container 3 to the speed of chain 2. In
addition the design of machine 1 requires that a
flattened bag 4' shall be inserted into the open
container 3 in a vertical attitude, as shown in Figure 1,
although it has been formed in a manner which results in
it travelling bottom end first. The parallelogram
linkage of device 64 allows the flattened bag 4' to be
presented in the correct attitude and at the correct
speed for insertion into open container 3.
The swinging movement of the parallelogram linkage
is coordinated with the movement of the clip 64 from
right to left along the lower run of belt 75 so that, as
the flattened bag 4' approaches the open container 3, the
linkage is swinging leftward so that clip 64 is moving
faster than the speed of endless chain 2. However, as
the flattened bag 4' enters the open container 3, the
linkage reverses its direction of swing and commences to
swing to the right, thus reducing the velocity of
flattened bag 4' relative to that of the endless chain 2.
As the linkage swings to the right, the right-to-left
velocity of the flattened bag 4' equates to the
corresponding velocity of the endless chain 2 so that the
flattened bag 4' is moving at the same speed as the
container 3 as this closes.
As can be seen from Figure 9, the flattened bag 4'
is travelling endwise from left to right as it first
captured by a clip 64. In passing over the roller 77 its
attitude changes from horizontal to vertical. Then in
passage around roller 78 roller 99 engages with the cam
track 100 and rotates clip 64 through 90°. Thus as it
commences to travel back in a leftward direction along
the bottom run of belt 75 flattened bag 4' retains its
vertical attitude in readiness for insertion into the
open container 3. In passage around roller 79 roller 99
engages with cam track 101 which serves to rotate clip 64
through 90° again in readiness for capturing a further
flattened bag 4'.
Figures 12 and 13 illustrate a modified form of
container which, while generally similar to the container
of Figures 2 to 6, has a trap door arrangement in its
base instead of having a fixed base. In Figures 12 and
13 the same reference numerals have been used to identify
those parts which are essentially the same as those
present in the embodiment of Figures 2 to 6.
In the front half 25 of the modified container of
Figures 12 and 13 plenum chamber 48 is closed on its
upper side by a fixed part 201 which forms part of the
floor to container 3. The bottom wall means 25d of front
half 25 extends somewhat rearward (i.e. to the right as
illustrated in Figures 12 and 13) past the plane of
separation 45 and carries a pivotable member 202 mounted
on pivots 203. Rubber pads 204 and 205 are provided on
part 201 and member 202 respectively and grip the bottom
end of bag 4' in the closed condition of the container.
Member 202 is spring biased by means of a spring (not
shown) in a clockwise direction as depicted in Figures 12
and 13. As the two halves separate, as shown in Figure
13, so member 202 swings down and away from front half 25
to the position of Figure 13. In this way a wide gap is
formed between pads 204, 205 which minimises the risk of
the bottom end of a bag 4' hitting part of container 3
and not entering it correctly. When the container 3
closes, the lip 206 extending across the bottom of the
bottom wall means 24d of rear half 24 catches under the
free edge of flange 207 on member 202 and swings this
anti-clockwise, as depicted in Figures 12 and 13, to move
member 202 back to its closed position.