Note: Descriptions are shown in the official language in which they were submitted.
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This invention relates to wrapping apparatus and to a
method of wrapping.
Accor~ing to-one aspect of the present invention there
is provide~ wrapping apparatus comprising a structure on which
an article to be wrapped is supported and on which the article is
fed along an in-feed path, means for suspending a succession of
sheets of material across said path so that each sheet forms a
curtain against which one of said articles is fed whereby said
sheet is draped over the top of the respective article with
leading and trailing portions thereof hanging down adjacent
the leading and trailing faces of the article, the trailing portion
having an end part, an article supporting conveyor onto which the
article is fed from said structure for support and conveyance by
the conveyor, a lower part of the leading, hanging portion of the
sheet being tucked beneath the article as the article moves onto the
conveyor and being held against the underface of the article by said
conveyor, the conveyor having a transverse slot, means for urging
said end part of the trailing portion of said sheet downwardly thr-
ough said slot, and means far then temporarily preventing said
article from moving with said conveyor which thus advances with
respect to the article whereby said slot carries the said end
part of said trailing portion beneath said article and overlaps
the said end part of said trailing portion with said lower part
of said leading portion.
Said conveyor means can be a roller conveyor including
freely rotatable, spaced apart rollers, said slot being formed
by the gap between two adjacent rollers.
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Means, such as an air blast or a tucking bar, can
be provided for forcing said trailing portion downwardly through
said slot. The tucking bar can be mounted on an endless conveyor
having an operative run which converges with said conveyor.
Preferably, said bar is pivotally mounted on said endless con-
veyor and hangin~ therefrom~
Said means for temporarily preventing the article
from moving with the conveyor can comprise a clamp element
arranged to move downwardly into contact with the article and
prevent movement thereof.
~ ccording to a.further aspect of the present invention
there is provided a method of wrapping a sheet of wrapping mat-
erial around an article, the method comprising advancing the
article along an in-feed path onto a conveyor for support by
the conveyor and advance at the same speed as the conveyor, sus-
pending a succession of discrete sheets of wrapping material
across said in-feed path in advance of said conveyor, each sheet
extending to below the article travelling along said in-feed
path and each advancing article, when it contacts that one of
XO the sheets which is suspended in front of it, causing the
portion of the sheet which is hanging down below the article
to be tucked between the underside of the article and the con-
veyor, the remainder of the sheet being draped over the article
with a portion hanging down behind the trailing face of the
article, feeding the end part of the said portion of the sheet
which is behind said trailing face downwardly through a slot
in said conveyor to a level below said conveyor, and then
temporarily preventing said article from moving with the con-
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veyor so that the conveyor advances with respect to the articleand said end part of said sheet is carried beneath the article
by the conveyor slot and overlaps said tucked portion.
In one form of the method the article is held
stationary while said trailing part of said sheet is carried
beneath the article~ In an alternative form of the method,
movement of the article with the conveyor is temporarily inter-
rupted by displacing it in the direction opposite to the direction
of movement of the conveyor and then releasing it for further
O
1 movement with the conveyor.
. For a better understanding of the present invention,
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and to show how the same may be carried into effect,
: reference will now be made, by way of example, to:the
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accompanying drawings in which:-
Figure 1 is a side elevation of wrapping apparatus;
Figure 2 is a section on the line II-II of Figure
l;
Figure 3 is a view taken in the same direction as
Figure 1 and showing a modified form of one section of the
apparatus;
Figure 4 is a top plan view of the section shown
in Figure 3;
Figure S is a detail of a modified form of a part
of the apparatus; and
Figures 6 to 10 diagrammatically illustrate the
wrapping method of the apparatus of Figure 1.
The apparatus illustrated comprises a machine
frame 10 including transverse members 12 and two side plates
14. One side plate has been omitted to show the portion of
the apparatus between the side plates and a number of
transverse members 12 have also been omitted from the
drawings to avoid such detail obscuring the working parts of
the apparatus.
The apparatus includes a section 16 for severing
wrapping material in web form into sheets, a vertical feed
structure 18 for feeding sheets of wrapping material down-
wardly from the section 16, an article infeed conveyor 20, a
main conveyor 22 and a sheet manipulating arrangement 24.
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The framework for supporting these components has largely
been omitted from the drawings. The arrangement 24 is
mounted between two upward extensions 26 of the side plates
14.
The section 16 comprises a drum generally in-
dicated at 28. The drum comprises a cylinder 30 of a
material which resists build-up of static electricity.
Nylon is a suitable material and it has been found that a
sheet of this can be bent to cylindrical form, transversely
welded and then skimmed so as to provide an outer surface
which is cylindrical. The ends of the cylinder 30 are
closed by discs 32 and 34 (see particularly Figures 3 and
4). A solid shaft 36 protrudes from the disc 32, this shaf*
being rotatably supported in a bearing (not shown) carried
by a portion of said framework which projects upwardly from
the side plates 14. A hollow, stationary shaft 38 passes
through the disc 34, there being a bearing diagrammatically
illustrated at 40 (see Figure 4) between the shaft 38 and
the disc 34. The shaft 38 forms part of a fan 42. The fan
42 includes a casing 44 in which there is a rotor (not
shown) the rotor being driven by a motor contained within a
sub-casing 46. The fan outlet is diagrammatically shown at
48. The shaft 38 is supported by a further part of said
framework.
The section 16 further includes a cutter unit 50
which is shown in Figures 3 and 4. Only the cutter 52 of
the unit has been shown in Figure 1.
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The unit 50 is mounted on a pair of radially
extending arms 54 which are themselves mounted one on each
of the shafts 36 and 38. A cross-bar 56 links the two arms
54 and a wire support arranged parallel to the cross-bar 56
is shown at 58. A wire 60 is carried by the wire support
58, the wire support and wire 60 together forming the cutter
52. Air cylinders 62 have their bodies mounted on the cross-
bar 56 and their rods connected to the wire support 58. The
cylinders 62 can be double acting. Alternatively, the
cylinders can be single acting and return springs can be
provided for retracting the wire support 58 after operation
of the air cylinders 62.
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A further air cylinder 64 has its body mounted on
a cross member 66 of the machine framework. A flexible wire
64.1 connects the piston of the air cylinder to the cross-
bar 56. A spring 68 is connected between the cross-bar 56
and a further cross member 70 of the machine framework.
Further air cylinders, or solenoids, can be mounted on the
arms 54. When actuated, these engage the discs 32 or 34 to
ensure that the cutter unit moves in an arc with the drum.
A reel 72 (Figure 1) of wrapping material in web
form is mounted adjacent the drum 28. The web feeding off
the reel 72 is shown at W and it will be seen that this
passes between a guide roller 74 and the drum 28 before
passing upwardly over the drum and thence, on the remote
side of the drum, downwardly between the drum 28 and the
vertical feed structure 18.
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~ A drive roller 76 is provided beneath the drum 28,
this roller being in face-to-face contact with the drum 28
and driving it by frictional contact.
The cylinder 30 is formed with a plurality of
apertures 78 (see particularly Figure 4) which pass through
the cylinder 30 and thus place the interior of the drum in
communication with the exterior.
The vertical feed structure 18 comprises upper and
lower shafts 80 and 82 at least one of which is driven. The
shafts 80 and 82 carry toothed sprockets 84 and two parallel
belts 86 and 88, each toothed on one of their faces, are
entrained around the sprockets 84.
Vertically extending vacuum chambers 90 and 92 are
provided between the runs of the belts 86 and 88 respectively.
The chambers 90 and 92 are linked by a plenum chamber 94 and
a fan 96 is connected to the chamber 94. The downward run of
each belt 86 and 88 is in contact with the adjacent face of
the respective vacuum chamber 90 and 92.
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Beneath the belts 86 and 88 the walling of each
vacuum chamber 90 and 92 has a vertically extending slot 98
(Figure 2) therein, the belts 86 and 88 overlying these
slots. The edge regions of the belts 86 and 88, by engaging
the longitudinally extending portions of the walling of the
vacuum chambers 90 and 92 which lie on each longitudinal
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side of the slots 98, form seals which minimise ingress of
atmospheric air into the chambers 90 and 92. Each belt 86 and
88 is formed, throughout its length, with apertures 100 which
register with the slots 98.
Simply by way of example, the slots 98 can be
approximately 5mm wide and the apertures in the belts 86 and 88
can have a 5mm diameter and be spaced at 25mm centres.
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In Figure 1 the return runs of the belts 86 and 88
are shown as being close to the non-operative faces of the
chambers 90 and 92. In Figure 3 an additional pair of guide
sprockets 102 are provided, these holding the return runs of
the belt away from the chambers 90 and 92. In this form the
lower sprockets 84 are somewhat larger than the upper
sprockets 84.
The infeed conveyor 20 comprises a pair of chains 104
carrying flight bars 106. The chains 104 are entrained around
- sprockets 108. `
A support 110 is provided for the series of articles
A which are to be wrapped. The articles A feed from a somewhat
raised support 112 onto the support 110 and are moved forward
in timed relationship on this latter support by the flight bars
106. It will be seen that the support 110 passes between the
belts 86 and 88 (see particularly Figure 2). The left hand end
of the support 112 is cyclically tilted upwardly during
operation to halt the next article of the incoming series.
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The main conveyor 22 is a roller conveyor and
comprises two laterally spaced chains 114 entrained around a
series of sprockets 116. The rollers of the conveyor are
referenced 118 and these are freely rotatable about their
own longitudinal axes with respect to mounting bosses (not
shown) carried by the chains.
The main conveyor 22 has a horizontal upper run
which is in substantially the same plane as the upper face
of the support 110. Chain supports, not shown, can be
provided for preventing sagging of the upper run. This upper
run passes beneath the sheet manipulating arrangement 24,
beneath a brake 120 provided for temporarily interrupting
movement of the articles in the feed direction, and into a
heat shrink tunnel 122 only the inlet end portion of which
has been shown.
The sheet manipulating arrangement 24 comprises
two endless chains 124 which are entrained around three
sprockets 126, the chains 124 forming an endless conveyor.
The sprockets 126 guide the chains 124 along a triangular
path which includes a horizontal return run 128 and an
operative run 130 which slopes downwardly and converges with
the upper horizontal run of the main conveyor 22. A plurality
of tucking bars 132 are pivotally mounted on the chains 124
and hang downwardly therefrom.
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The brake 120 is mounted on a cross bar 134 of the
machine framework and comprises an air cylinder 136 mounted
in a vertical position on the bar 134. The rod 138 of the
air cylinder extends downwardly through the bar 134 and
carries a plate 140 at the lower end thereof. The plate 140
may be in the form of a disc.
An alternative form of brake is shown in Figure 5.
In this form, the cross-bar 134 carries a rotatable cam 142.
The cam 142 acts on the plate 140 which is guided for
vertical movements by means of a stem 144. A slot 146 is
provided in this stem and a fixed element 148 passes through
the slot. A spring 150 acts between the stem 144 and the
fixed element 148 to hold the plate 140 against the peri-
phery of the cam 142.
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In use of the apparatus, the drum 28 and the belts
86 and 88 are driven continuously. As the linear speed of
the downward run of the belts 86 and 88 must equal the
peripheral speed of the drum 28, the driven sprockets 84 and
the roller 76 are driven in timed relationship to ensure
that this requirement is met.
~ he web W is fed from the reel 72, beneath the
guide roller 74 and thence o~er the periphery of the drum
28. The fan 42 creates a sub-atmospheric pressure within
the drum 28 so that the air impervious web W is drawn against
the periphery of the drum.
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The cutter unit 50 is operated in timed relationship
with infeed of articles A by the infeed conveyor 20. For
example, a photoelectric cell can be provided, the succession
of articles A interrupting the light beam to the photoelectric
cell and thereby actuating a solenoid valve (not shown)
which feeds air to the air cylinders 62 and 64.
Upon air being fed to the air cylinders 62, the
cutter 52 comprised by the wire support 58 and the wire 60
is displaced radially inwardly into engagement with the web
W. ~he wire 60 can carry a continuous heating current or,
alternatively, a heating current circuit can be completed at
the same time as said solenoid operated valve is actuated.
The wire 60 serves to sever a sheet of wrapping material
from the web. The sheets are referenced S in Figures 1, 2,
6 etc.
At the time that the air cylinders 62 are actuated
to thrust the wire support 58 radially inwardly, the rear
chamber of the air cylinder 64 is also subjected to pressure.
Its piston moves faster than does the cutter 52 so that the
wire 64.1 goes slack. Under the influence of the spring 68
and the rotation of the drum 28, the cutter 52 swings on the
arms 54 in an arc about the common axis of the shafts 36 and
38.
After a timed interval, supply of air to the rear
chambers of the air cylinders 62 ceases. If double acting
aix cylinders are used, air is immediately thereafter supplied
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to the front chambers to retract the wire support 58.
Alternatively, if single acting cylinders are employed, then
the return springs are effective to withdraw the wire support
58. The cutter unit, however, continues to move with the drum
under the influence of the spring 68, and the slack in the wire
64.1 is taken-up. Air is supplied to the front chamber of the
cylinder 64 shortly after the wire support is withdrawn from
the drum 28 so that the cutter unit 50 is returned to its
initial position to commence the next cycle of operations.
Motion of the unit 50 with the drum 28 provides the
requisite cutting time without displacing the web on the drum.
Furthermore, as the cutter unit continues to move with the drum
while the cutting wire is being withdrawn, there is no tendency
for the cutter unit to displace the web. Because suction is
constantly applied via the apertures 78 to the radially inner
face of the web, the web remains firmly in position on the
periphery of the drum.
The vacuum effect created at those apertures 100
which register with the slots 98 is greater than the vacuum
effect created at the apertures 78. Consequently, at the region
where the belts 86 and 88 run tangentially to the drum 28, the
sheets S are transferred from the drum 28 to the belts 86 and
88 and are conveyed downwardly therewith. To assist with this
transfer, the drum 28 can be provided with fixed internal
partitions such as are shown at 152 in Figure 3. In this form
the drum must include a fixed shaft which passes axially
therethrough and on which the partitions 152 are mounted.
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Seals are provided between the cylinder 30, discs 32 and 34 and
the partitions 152. Between the partitions atmospheric
pressure conditions are permitted to prevail. This construc-
tion ensures that, at the region where the sheet comes under
the influence of suction at the apertures 100, it is not drawn
onto the drum 28.
The sheets S are held along their peripheries (see
particularly Figure 2) by the belts 86 and 88 and are fed
downwardly with the belts.
The leading edge portion L of each sheet passes to a
level which is below the upper surface of the support 110. At
this stage the sheet forms a curtain ahead of the incoming
article A which, at this moment, is fed forward by the flight
bar 106 behind it into engagement with the sheet S. As each
article is fed forward by one of the flight bars 106, the
support 112 tilts downwardly to permit another article to be
urged into it. This article in turn feeds onto the support 110
the article already on the support 112.
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The rate of feed of the article into engagement with
the sheet S equals or exceeds the rate of downward feed of the
sheet so that, as the article moves onto the upper run of the
main conveyor 22, the sheet S is stripped from the belts 86 and
88 without being crumpled and is draped over the article. The
configuration of the sheet S immediately after being stripped
from the belts 86 and 88 can be seen by referring to Figure 6
and to the centre article of the seven illustrated in Figure 1.
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The portion L is between the article and the rollers 118 of the
conveyor 22.
The article moves to the right with the main conveyor
and as it does so that one of the tucking bars 132 which is
moving down the operative run 130 enters the space between that
article and the following article in close proximity to the
trailing face of the article.
The tucking bar reaches its lowest position as it
passes around the lowermost sprocket 126 and in this condition
its lower portion has passed through the transverse slot
between two adjacent rollers 118 of the main conveyor 22. It
will be seen that the trailing edge portion T of the sheet S,
before bein~ encountered by a tucking bar 132, lies on the
rollers 118 of the main conveyor 22. As the tucking bar passes
between the rollers, it carries the trailing edge portion T of
the sheet S through the inter-roller slot with it. This is
illustrated in Figure 7 which shows the trailing edge portion T
in its positions before and after being manipulated by the bar
132.
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As each article passes beneath the brake 120, air is
fed to the air cylinder 136. The plate 140, which forms a
clamp element, is thus thrust downwardly into engagement with
the article. The frictional restraint applied is sufficient to
haIt progress of the article in the feed direction. While the
article is so held, the rollers 118 rotate as they pass beneath
it.
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273
The roller 118.1 (Figure 8) which is behind the slot
through which the trailing edge portion T of the sheet S hangs,
commences to over-run the portion T immediately the article A
ceases to move in the feed direction. This condition is
illustrated in Figure 8 from which it will be seen that said
slot has moved in the feed direction with respect to the
article and the roller 118.1 has commenced to press the portion
T against the underside of the article A. An air blower
diagrammatically shown at 154 directs a continuous flow of air
against the leading edge portion L to hold it against the
underside of the article. Any inherent stiffness of the
material of sheet S assists in this regard.
As the roller 118.1 moves forwardly with respect to
the article A (see Figure 9) more and more of the trailing edge
portion T is placed in juxtaposition to the underside of the
article A. Eventually the condition of Figure 10 is reached
where the trailing and leading edge portions have been
overlapped with respect to one another. Once this condition
has been reached, the brake 120 is released and the article is
free to move once more with the conveyor 22.
As the article enters the tunnel 122, the overlapped
trailing and leading edge portions of the sheet S are
subjected either to radiant heat from a heating element
diagrammatically shown at 156 or are subjected to a heated air
blast. This seals the overlapped portions to one another.
Thereafter the entire article is subjected to general heating
to shrink the sheet tightly around the article A.
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When the brake of Figure 5 is employed, timing is
achieved by means of the drive arrangement of the cam 142. The
configuration of this cam is such that there is a dwell period
during which the plate 140 is held in contact with the article.
The céntre-to-centre distance of the series of articles
on the conveyor 22 is determined by the spacing of the flight
bars 106. The pitch of the bars 132 equals that of the articles.
The brake 120 can be operated in timed relationship with the
bars 106. Alternatively there can be a photoelectric cell for
detecting the presence at the brake 120 of each article. This
cell actuates the brake.
The length of each sheet S depends on the rate of
rotation of the drum 28. It will be understood that by changing
this rate of rotation without increasing the rate of motion of
any other part of the apparatus, or the pitch spacing or size
of the articles, a greater or lesser degree of overlap between
the trailing and leading edge portions can be obtained. Drum
rotational speed can be varied by replacing one of the sprockets
(not shown) in the drive to the roller 76 by a sprocket with a
different number of teeth.
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