Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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WRAP MACHINE
BACKGROUND OF THE INVENTION
[0001] Wrapping machines have been developed for wrapping plastic film around
items
on a pallet to retain the items for shipping and the like. Known wrapping
machines
include a film dispenser mounted on an arm to rotate about the pallet and
thereby wrap
the items on the pallet. The film dispenser may also be mounted for vertical
travel such
that the film is wrapped around the items in a spiral manner. Other known
wrapping
machines include a rotary table upon which the pallet is placed. In this type
of machine,
the wrapping device is mounted to a stationary vertical structure. During the
wrapping
process, the table and pallet thereon are rotated, and the wrapping device
travels
vertically to thereby spiral wrap the items on the pallet. Known wrapping
machines
include a gripper that grips the end of the film to thereby tension the film
as it is fed
from the filin dispenser. Known grippers are pneumatically powered, and
therefore
require a supply of compressed air in addition to the electrical power that is
required to
operate the other components of the wrapping machine. The need for a supply of
compressed air to operate the gripper often results in extra expense and/or
inconvenience, particularly in facilities that do not already have a supply of
compressed
air.
BRIEF DESCRIPTION OF THE DRAWINGS
[0002) Fig. 1 is perspective view of a wrap machine according to one aspect of
the
present invention;
[0003] Fig. 2 is a right front view of the wrap machine of Fig. 1;
[0004] Fig. 3 is a left front view of the wrap machine of Fig. 1;
[0005] Fig. 4 is a rear view of the wrap machine of Fig. 1;
[0006] Fig. 5 is a top view of a gripper for wrap machines according to the
present
invention, with the gripper being in an open position;
[0007] Fig. 6 is a top view of the gripper wrap machines according to the
present
invention, with the gripper being in an open position;
[0008] Fig. 7 is a perspective view of the electrically powered rack and
pinion
mechanism and gripping members;
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[0009] Fig. 8 is a partially schematic perspective view of another wrapping
machine
according to another aspect of the present invention, wherein the grippers are
mounted
to a rotary table.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
(0010] For purposes of description herein, the terms "upper," "lower,"
"right," "left,"
"rear " "front " "vertical " "horizontal " and derivatives thereof shall
relate to the
> > > >
invention as orientated in Fig. 1. However, it is to be understood that the
invention may
assume various alternative orientations, except where expressly specified to
the contrary.
It is also to be understood that the specific devices and processes
illustrated in the
attached drawings, and described in the following specification are simply
exemplary
embodiments of the inventive concepts. Hence, specific dimensions and other
physical
characteristics relating to the embodiments disclosed herein are not to be
considered as
limiting.
(0011] The reference number 10 (Fig. 1) generally designates a wrap machine of
the
present invention. The wrap machine 10 includes a frame 12, a rotating arm 14
having
a stretch wrapping device 16 thereon and a gripper housing 18. The frame 12
includes a
substantially C-shaped base 20, a vertical frame member 22, an upper
horizontal frame
member 24 and a pair of struts 26 extending between the base 20 and the upper
horizontal frame member 24. The frame 12 further includes a cantilevered arm
28
extending from the upper horizontal frame member 24. The rotating arm 14 is
connected to the cantilevered arm 28. The rotating arm 14 has an inverted L-
shape,
with an end of the horizontal portion rotatably connected to the end 29 of the
cantilevered arm 28. A first electric motor and drive assembly 15 rotates arm
14 360°
about the end of cantilevered arm 28. The stretch wrapping device 16 is
operably
coupled to a second electric motor and drive assembly 19, and moves up and
down the
vertical portion of the rotating arm 14 to wrap a film web about a plurality
of items
placed on a pallet, which is placed within a wrapping area 17 defined by the C-
shaped
base 20 of the frame 12. The stretch wrapping device 16 (Fig. 3) includes a
web
dispenser 30 which supports a roll 32 of conventional film web 34, and
prestretch rollers
which stretch the film web 34 before it is dispensed from tlhe web dispenser
30 over the
items on the pallet. In the illustrated example, the rotating arm 14 further
includes a
wipe and burn mechanism 45 for burning the film web 34 once the items on the
pallet
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have been wrapped and for wiping a free end of the film web 34 after it has
been burnt
into contact with the rest of the film web 34 on the items on the pallet. All
of the
elements discussed above, except the gripper housing 18, are conventional
items and are
well known to those skilled in the art.
[0012) In the illustrated example, the gripper housing 18 is spaced away from
the C-
shaped base 20 of the frame 12. As illustrated in Figs. 1-4, the stretch
wrapping device
16 is configured to rotate in a space 21 located between the gripper housing
18 and the
C-shaped base 20. The gripper housing 18 preferably includes a pair of
gripping
members 50 extending from a top surface 23. As discussed in more detail below,
the
gripping members 50 are electrically activated, with the electricity being
conducted to
the gripper housing 18 by a 24 volt ribbon wire 52 that has a low profile. The
ribbon
wire 52 extends between the C-shaped base 20 of the frame 12 and the gripper
housing
18. The frame 12 includes a conventional electrical connection for providing
power to
all parts of the wrap machine 10.
[0013) Preferably, the gripping members 50 are connected to a rack and pinion
system
55 (Fig. 7) that moves the gripping members 50 from an open position as shown
in Fig.
to a closed position as shown in Fig. 6. An electrically powered linear
actuator 57
includes an output shaft or member 58 that shifts horizontally upon actuation
of linear
actuator 57. The output member 58 extends through an opening in an angle
bracket 61,
and angle bracket 61 is fixed to rack 56. Angle bracket 61 is positioned
between stop
members 59 and 60 of the output member 58 such that stops 59 and 60 contact
bracket
61 and shift rack 56 horizontally upon actuation of linear actuator 57. Rack
56 extends
through a guide 64 and teeth 63 of rack 56 engage a gear 65 to rotate a first
gripper
member 50A. A pair of gears 66 and 67 mesh to thereby cause gripper member 50B
to
rotate in an opposite direction relative to gripper 50A. When the output shaft
58 is in
the extended position as illustrated in Fig. 7, gripper members 50A and 50B
are rotated
to the open position. As output member 58 is retracted, a spring 62 contacts
the vertical
wall 68 of angle bracket 61, thereby pulling the rack 56 towards the actuator
57 and
rotating the gripper members 50A and 50B to the closed position. The spring 62
thereby
provides a relatively constant, controlled force acting on the film between
the gripper
members 50A and 50B, and reduces or eliminates the variations in force that
would
otherwise occur due to varying thicknesses of the film and/or variations in
the amount of
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travel of output member 58 of actuator 57. Other resilient members or
arrangements
providing a constant gripping force could also be utilized. For example,
rubber or foam
could be positioned on the edges of the gripper members SOA and/or SOB. The
linear
electrically powered actuator 57 is secured to a base member 71 by an actuator
bracket
70, and gripping members SOA and SOB are rotatably mounted in brackets 69. The
gripper housing 18 is preferably bolted into position on the ground by
fasteners 73 or
other suitable anchoring arrangements.
[0014] In use, the wrap machine 10 is used by placing the pallet full (or
partially full) of
items within the area defined by the C-shaped base 20 of the frame 12 and with
a circle
defined by the rotation of the vertical portion of the rotating arm 14, with
the pallet
abutting the gripper housing 18. To begin, a free end of the film web 34 is
clamped by
the gripping members 50. Once the pallet is in position, the rotating arm 14
begins to
rotate, thereby wrapping the pallet and the items on the pallet with the film
web 34.
With the wrap machine 10 of the present invention, the lowest portion of the
stretch
wrapping device 16 can get very close to the ground because the stretch
wrapping device
only has to clear the ribbon wire 52 in the lowest portion of rotation.
Therefore, the
pallet does not have to be raised off of the ground and/or the gripping
members 50 do
not have to be located in the ground to be able to wrap the pallet.
Previously, the pallet
was placed on a platform and/or the gripping members 50 were located in the
ground to
be able to wrap the pallet. Additionally, the gripper housing 18 has a height
of about 3
to 3.25 inches, thereby allowing the film web 34 to be wrapped about the
pallet without
the gripper housing 18 interfering.
[0015] As the stretch wrapping device 16 spins about the items on the pallet,
moving
vertically to wrap the all of the items, the gripping members 50 can release
the free end
of the film web 34. Thereafter, when all of the items on the pallet have been
wrapped,
the rotating arm 14 can move back to an initial position that the rotating arm
14 was in
before the wrap sequence begun. Thereafter, the gripping members 50 can once
again
be activated to grab the film web 34 between the items on the pallet and the
stretch
wrapping device 16. The wipe and burn mechanism 45 will then move into contact
with
the film web 34 between the items on the pallet and the stretch wrapping
device 16 to
burn the film web 34 to thereby sever the film 34 and to wipe a free end of
the film web
34 extending from the items on the pallet into contact with the film web 34
about the
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items on the pallet. The pallet can there be removed and another pallet can be
placed into
position to start the process over again to wrap items on the second pallet
with the film
web 34.
[0016] The gripper housing 18 and grippers 50A and SOB may also be utilized
for a
rotary table wrapping machine 80. The gripper mechanism of Fig. 7 and housing
18 are
mounted to a rotary table 82 adjacent an edge of table 82, and thereby rotates
as table 82
is rotated. A stretch wrapping device 16 dispenses a film web in a known
matter, and
travels vertically along vertical structure 81 of wrapping machine 80. A
conventional
wipe and burn mechanism 45 is also provided. Electric drive assemblies 84, 85
of a
conventional known design provide for vertical movement of the stretch
wrapping device
16 and for rotary movement of rotary table 82. The housing 18 is mounted on
upper
surface 83 of rotary table 82 and thereby provides a stop to position pallets
or other
items on table 82. A conventional slip ring arrangement or the like provides
electrical
power from the main power supply source to the linear electric actuator
mounted to the
rotary table 82. In use, a pallet is placed on rotary table 82, and an end
portion of the
film web is secured by grippers 50A and 50B upon actuation of linear actuator
57.
Table 82 is then rotated, and stretch wrapping device 16 moves vertically to
thereby
wrap the items on rotary table 82.
[0017] The above description is considered that of the preferred embodiment
only.
Modification of the invention will occur to those skilled in the art and to
those who make
or use the invention. Therefore, it is understood that the embodiment shown in
the
drawings and described above is merely for illustrative purposes and not
intended to
limit the scope of the invention.
