Canadian Patents Database / Patent 2787780 Summary

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(12) Patent Application: (11) CA 2787780
(54) English Title: DEMAND THROTTLE METHODS AND APPARATUSES
(54) French Title: PROCEDES ET APPAREILS DE PAPILLON DES GAZ A LA DEMANDE
(51) International Patent Classification (IPC):
  • B65B 11/02 (2006.01)
  • B65B 11/00 (2006.01)
  • B65B 11/04 (2006.01)
(72) Inventors :
  • MOORE, PHILIP R. (United States of America)
  • LANCASTER, PATRICK R., III (United States of America)
  • JOHNSON, RICHARD L. (United States of America)
  • NORRIS, JOSEPH D. (United States of America)
(73) Owners :
  • MOORE, PHILIP R. (United States of America)
  • JOHNSON, RICHARD L. (United States of America)
  • NORRIS, JOSEPH D. (United States of America)
  • LANTECH.COM, LLC (United States of America)
(71) Applicants :
  • MOORE, PHILIP R. (United States of America)
  • JOHNSON, RICHARD L. (United States of America)
  • NORRIS, JOSEPH D. (United States of America)
  • LANTECH.COM, LLC (United States of America)
(74) Agent: MACRAE & CO.
(74) Associate agent: MACRAE & CO.
(45) Issued:
(86) PCT Filing Date: 2011-01-21
(87) Open to Public Inspection: 2011-07-28
(30) Availability of licence: N/A
(30) Language of filing: English

(30) Application Priority Data:
Application No. Country/Territory Date
61/297,709 United States of America 2010-01-22

English Abstract

An apparatus (100) for wrapping a load (138) with packaging material (142) may include a packaging material dispenser (140) for dispensing packaging material. The apparatus may also include a relative rotation assembly (129) for providing relative rotation between the load and the packaging material dispenser. The apparatus may further include a mechanical connection (133) operatively coupling the packaging material dispenser to the relative rotation assembly. The relative rotation assembly may be configured to drive the packaging material dispenser through the mechanical connection. The apparatus may further include a force exerting mechanism (181) operatively coupled to the mechanical connection. The apparatus may further include a sensing element (194) configured sense a characteristic of dispensed packaging material. The sensing element may be operatively coupled to the mechanical connection. The force exerting mechanism and the sensing element may be configured to control the mechanical connection to maintain a selected ratio of packaging material dispensed to demand for packaging material at the load for at least a portion of a wrap cycle.


French Abstract

La présente invention a trait à un appareil (100) permettant d'emballer une charge (138) avec un matériau d'emballage (142), lequel appareil peut inclure un distributeur (140) de matériau d'emballage permettant de délivrer du matériau d'emballage. L'appareil peut également inclure un ensemble de rotation relative (129) permettant de fournir une rotation relative entre la charge et le distributeur de matériau d'emballage. L'appareil peut en outre inclure une connexion mécanique (133) couplant de manière fonctionnelle le distributeur de matériau d'emballage à l'ensemble de rotation relative. L'ensemble de rotation relative peut être configuré de manière à entraîner le distributeur de matériau d'emballage au moyen de la connexion mécanique. L'appareil peut en outre inclure un mécanisme exerçant une force (181) couplé de manière fonctionnelle à la connexion mécanique. L'appareil peut en outre inclure un élément de détection (194) configuré de manière à détecter une caractéristique d'un matériau d'emballage délivré. L'élément de détection peut être couplé de manière fonctionnelle à la connexion mécanique. Le mécanisme exerçant une force et l'élément de détection peuvent être configurés de manière à contrôler la connexion mécanique afin de maintenir un rapport sélectionné de matériau d'emballage délivré à la demande pour le matériau d'emballage de la charge pour au moins une partie d'un cycle d'emballage.


Note: Claims are shown in the official language in which they were submitted.




WHAT IS CLAIMED IS:

1. An apparatus for wrapping a load with packaging material,
comprising:
a packaging material dispenser for dispensing packaging material;
a relative rotation assembly for providing relative rotation between the load
and the packaging material dispenser;
a mechanical connection operatively coupling the packaging material
dispenser to the relative rotation assembly, wherein the relative rotation
assembly
is configured to drive the packaging material dispenser through the mechanical

connection;
a force exerting mechanism operatively coupled to the mechanical
connection; and
a sensing element configured sense a characteristic of dispensed packaging
material, the sensing element being operatively coupled to the mechanical
connection;
wherein the force exerting mechanism and the sensing element are
configured to control the mechanical connection to maintain a selected ratio
of
packaging material dispensed to demand for packaging material at the load for
at
least a portion of a wrap cycle.

2. The apparatus of claim 1, wherein the force exerting mechanism and
the sensing element are configured to maintain the ratio of packaging material

dispensed to demand at a level sufficient to produce a desired wrap force on
the
load.

3. The apparatus of claim 1, wherein the force exerting mechanism and
the sensing element are configured to maintain the ratio of packaging material

dispensed to demand at a level sufficient to produce a desired containment
force
on the load.

4. The apparatus of claim 1, wherein the force exerting mechanism and
the sensing element are configured to maintain the ratio of packaging material

dispensed to demand at a level sufficient to meet the containment needs of the

load.
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5. The apparatus of claim 1, wherein the force exerting mechanism and
the sensing element are configured to maintain the ratio of packaging material

dispensed to demand within a range of values sufficient to maintain at least
one of
a wrap force and a containment force exerted on the load in a range sufficient
to
meet containment needs of the load.

6. The apparatus of claim 1, wherein the force exerting mechanism
includes a spring member configured to exert a force on the mechanical
connection.

7. The apparatus of claim 6, wherein the force exerting mechanism
includes a compression spring.

8. The apparatus of claim 6, wherein the sensing element is configured
to exert a force on the mechanical connection based at least in part on the
sensed
characteristic.

9. The apparatus of claim 8, wherein the force exerted by the force
exerting mechanism and the force exerted by the sensing element oppose one
another.

10. The apparatus of claim 9, wherein the mechanical connection
includes an input and an output.

11. The apparatus of claim 10, wherein the mechanical connection is
configured such that connectivity between the input and the output increases
when
the force exerted by the sensing element overcomes the force exerted by the
force
exerting mechanism.

12. The apparatus of claim 10, wherein the mechanical connection is
configured such that connectivity between the input and the output decreases
when
the force exerted by the force exerting mechanism overcomes the force exerted
by
the sensing element.
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13. An apparatus for wrapping a load with packaging material,
comprising:
a packaging material dispenser for dispensing packaging material;
a relative rotation assembly for providing relative rotation between the load
and the packaging material dispenser;
a mechanical connection operatively coupling the packaging material
dispenser to the relative rotation assembly, wherein the relative rotation
assembly
is configured to drive the packaging material dispenser through the mechanical

connection; and
a sensing element configured to sense a change in demand for packaging
material at the load and adjust the mechanical connection in response to the
change in demand to maintain a ratio of packaging material dispensed to demand

in a selected range for at least a portion of a wrap cycle.

14. The apparatus of claim 13, wherein the sensing element is configured
to engage a portion of the packaging material extending between the packaging
material dispenser and the load to sense the change in demand.

15. The apparatus of claim 13, wherein the demand is an instantaneous
demand.

16. The apparatus of claim 13, wherein the sensing element is configured
to respond to the change in packaging material demand by moving from a first
position to a second position.

17. The apparatus of claim 16, wherein the sensing element includes a
shaft including a hinged fixed end and a free end, the shaft being configured
to
swing about the hinged fixed end between the first position and the second
position.

18. The apparatus of claim 17, further including a force exerting
mechanism coupled to the shaft, the force exerting mechanism being configured
to
exert a force on the shaft.


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19. The apparatus of claim 18, wherein the force exerting mechanism is
configured to maintain the ratio of packaging material dispensed to demand
substantially constant as demand changes by controlling positioning of the
sensing
element with the force exerted by the force exerting mechanism.

20. The apparatus of claim 18, wherein a first portion of the force exerting
mechanism is coupled to the shaft.

21. The apparatus of claim 20, wherein a second portion of the force
exerting mechanism is coupled to a frame portion of the packaging material
dispenser.

22. The apparatus of claim 17, further including a force exerting
mechanism coupled to the mechanical connection, the force exerting mechanism
being configured to exert a force on the mechanical connection.

23. The apparatus of claim 22, wherein the force exerting mechanism
includes an arm slidably received in a housing.

24. The apparatus of claim 23, wherein the force exerting mechanism
includes a spring engaging the arm and the housing, the spring being
configured to
bias the arm to an extended position relative to the housing.

25. The apparatus of claim 23, wherein the arm is coupled to the
mechanical connection, and the housing is coupled to a frame portion of the
packaging material dispenser.

26. The apparatus of claim 25, wherein the arm is selectively fastened
along a slot in the mechanical connection.

27. The apparatus of claim 26, wherein moving the arm along the slot in a
first direction increases the force exerted on the mechanical connection by
the force
exerting mechanism.

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28. The apparatus of claim 27, wherein moving the arm along the slot in a
second direction decreases the force exerted on the mechanical connection by
the
force exerting mechanism.

29. The apparatus of claim 13, wherein the mechanical connection
includes a mechanical input/output ratio control operatively coupling the
relative
rotation assembly to the packaging material dispenser.

30. The apparatus of claim 29, wherein the mechanical input/output ratio
control includes a hydrostatic transmission.

31. The apparatus of claim 29, wherein an input of the mechanical
input/output ratio control is operatively coupled to the relative rotation
assembly.
32. The apparatus of claim 31, wherein an output of the mechanical
input/output ratio control is operatively coupled to the packaging material
dispenser.
33. The apparatus of claim 32, wherein connectivity between the input
and the output of the mechanical input/output ratio control is determined at
least in
part by positioning of the sensing element.

34. The apparatus of claim 33, wherein movement of the sensing element
in a first direction increases connectivity between the input and output of
the
mechanical input/output ratio.

35. The apparatus of claim 34, wherein movement of the sensing element
in a second direction decreases connectivity between the input and output of
the
mechanical input/output ratio.

36. The apparatus of claim 34, wherein movement of the sensing element
in a second direction is indicative of a decrease in connectivity between the
input
and output of the mechanical input/output ratio.

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37. A method for wrapping a load with packaging material, the method
comprising:
providing relative rotation between a packaging material dispenser and the
load with a relative rotation assembly;
driving the packaging material dispenser to dispense packaging material with
the relative rotation assembly through a mechanical connection operatively
coupling the packaging material dispenser and the relative rotation assembly;
engaging a portion of the packaging material extending between the
packaging material dispenser and the load with a sensing element, wherein a
change of position of the sensing element is indicative of a change in demand
for
packaging material at the load; and
adjusting the mechanical connection based at least in part on movement of
the sensing element to maintain a ratio of packaging material dispensed to
demand
in a selected range for at least a portion of a wrap cycle.

38. The method of claim 37, wherein movement of the sensing element is
indicative of a change in load girth between a first portion of the load and a
second
portion of the load.

39. The method of claim 37, wherein movement of the sensing element is
indicative of a change in the shape of a portion of the load being wrapped.

40. The method of claim 37, wherein driving the packaging material
dispenser to dispense packaging material with the relative rotation assembly
through a mechanical connection includes driving the packaging material
dispenser
to dispense packaging material with the relative rotation assembly through a
mechanical input/output ratio control.

41. The method of claim 40, wherein adjusting the mechanical connection
operatively coupling the packaging material dispenser and the relative
rotation
assembly includes adjusting power transmission in the mechanical input/output
ratio control.

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42. The method of claim 40, wherein adjusting power transmission in the
mechanical input/output ratio control includes adjusting connectivity between
an
input of the mechanical input/output ratio control and an output of the
mechanical
input/output ratio control.

43. The method of claim 37, further including controlling movement of the
sensing element with an adjustable force exerting mechanism to maintain the
ratio
of packaging material dispensed to demand.

44. A method for wrapping a load with packaging material, the method
comprising:
providing relative rotation between a packaging material dispenser and the
load with a relative rotation assembly;
driving the packaging material dispenser to dispense packaging material with
the relative rotation assembly through a mechanical connection operatively
coupling the packaging material dispenser and the relative rotation assembly;
and
controlling the mechanical connection with a sensing element operatively
coupled to the mechanical connection;
engaging a portion of the packaging material extending between the
packaging material dispenser and the load with the sensing element to monitor
tension of the packaging material; and
moving the sensing element to control the mechanical connection to
maintain an amount of packaging material dispensed relative to the demand for
packaging material at the load in a selected range for at -east a portion of a

wrapping cycle.

45. The method of claim 44, wherein maintaining an amount of packaging
material dispensed relative to the demand for packaging material at the load
substantially constant includes maintaining the amount dispensed relative to
the
demand substantially constant as tension of the packaging material varies.

46. The method of claim 44, wherein tension in the packaging material
changes due to a change in load girth.

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47. The method of claim 44, wherein tension in the packaging material
changes due to a change in a shape of the load.

48. The method of claim 44, wherein driving the packaging material
dispenser to dispense packaging material with the relative rotation assembly
through a mechanical connection includes driving the packaging material
dispenser
with the relative rotation assembly through a mechanical input/output ratio
control.

49. The method of claim 48, wherein moving the sensing element
includes pivoting the sensing element about a hinged fixed end.

50. The method of claim 49, wherein pivoting the sensing element adjusts
the mechanical input/output ratio control.

51. The method of claim 44, further including controlling movement of the
sensing element with an adjustable force exerting mechanism.

52. The method of claim 44, wherein maintaining an amount of packaging
material dispensed relative to demand in a selected range includes maintaining
the
amount of packaging material dispensed relative to the demand substantially
constant for at least a portion of the wrapping cycle.

53. A method for wrapping a load with packaging material, the method
comprising:
providing relative rotation between a packaging material dispenser and the
load with a relative rotation assembly;
driving the packaging material dispenser to dispense packaging material with
the relative rotation assembly through a mechanical connection operatively
coupling the packaging material dispenser and the relative rotation assembly;
engaging a portion of the packaging material extending between the
dispensing assembly and the load with a sensing element operatively coupled to
a
control element of the mechanical connection;
exerting a force on the control element with an adjustable force exerting
mechanism; and


-46-




controlling the mechanical connection with the control element, through
positioning of the sensing element and force exerted by the adjustable force
exerting mechanism, to maintain a ratio of packaging material dispensed
relative to
demand for packaging material at the load substantially constant for at least
a
portion of a wrap cycle.

54. The method of claim 53, wherein exerting a force on the control
element includes exerting the force on the control element with a spring
device.
55. The method of claim 54, wherein exerting the force on the control
element with a spring device includes adjusting the force exerted on the
control
element by adjusting the spring device.

56. The method of claim 55, wherein adjusting the spring device includes
adjusting a length of the spring device.

57. The method of claim 53, wherein driving the packaging material
dispenser with the relative rotation assembly through a mechanical connection
includes driving the packaging material dispenser with the relative rotation
assembly through a mechanical input/output ratio control operatively coupling
the
relative rotation assembly to the packaging material dispenser.

58. The method of claim 57, wherein controlling the mechanical
connection with the control element includes adjusting connectivity between
the
input and output of the mechanical input/output ratio control.

59. The method of claim 57, wherein driving the packaging material
dispenser with the relative rotation assembly through a mechanical
input/output
ratio control includes driving the packaging material dispenser with the
relative
rotation assembly through a hydrostatic transmission.

60. The method of claim 59, wherein controlling the mechanical
connection with the control element includes adjusting a valve assembly in the

hydrostatic transmission.
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61. An apparatus for stretch wrapping a load, comprising:
a packaging material dispenser for dispensing packaging material, the
packaging material dispenser including a dispensing assembly for pre-
stretching
the packaging material;
a relative rotation assembly for providing relative rotation between the load
and the packaging material dispenser;
a mechanical connection operatively coupling the dispensing assembly to
the relative rotation assembly, wherein the relative rotation assembly is
configured
to drive the dispensing assembly through the mechanical connection;
a sensing roller configured to sense a change in demand for packaging
material at the load, and to move to adjust the mechanical connection in
response
to the change in packaging material demand; and
an adjustable force exerting mechanism operatively coupled to the sensing
roller, the adjustable force exerting mechanism being configured to control
movement of the sensing roller.

62. An apparatus for wrapping a load with packaging material,
comprising:
a packaging material dispenser for dispensing packaging material;
a relative rotation assembly for providing relative rotation between the load
and the
packaging material dispenser;
a mechanical connection operatively coupling the packaging material
dispenser to the relative rotation assembly, wherein the relative rotation
assembly
is configured to drive the packaging material dispenser through the mechanical

connection;
a force exerting mechanism operatively coupled to the mechanical
connection; and
a sensing element configured sense a characteristic of dispensed packaging
material, the sensing element being operatively coupled to the mechanical
connection;
wherein the force exerting mechanism and the sensing element are
configured to control the mechanical connection to maintain a wrap force
exerted
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by the dispensed packaging material on the load in a selected force range for
at
least a portion of a wrap cycle.

63. The apparatus of claim 62, wherein the force exerting mechanism and
the sensing element are configured to maintain the wrap force in the selected
force
range by maintaining a ratio of packaging material dispensed to demand for
packaging material at the load in a selected ratio range.

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Note: Descriptions are shown in the official language in which they were submitted.


CA 02787780 2012-07-20
WO 2011/091258 PCT/US2011/022066
DEMAND THROTTLE METHODS AND APPARATUSES

Description
[001] This application claims priority under 35 U.S.C. 119 based on U.S.
Provisional Application No. 61/297,709, filed January 22, 2010, the complete
disclosure of which is incorporated herein by reference..

Technical Field

[002] The present disclosure relates to methods and apparatuses for
wrapping a load with packaging material, and more particularly, stretch
wrapping.
Background

[003] Various packaging techniques have been used to build a load of unit
products and subsequently wrap them for transportation, storage, containment
and
stabilization, protection and waterproofing. One system uses wrapping machines
to
stretch, dispense, and wrap packaging material around a load. The packaging
material may be pre-stretched before it is applied to the load. Wrapping can
be
performed as an inline, automated packaging technique that dispenses and wraps
packaging material in a stretch condition around a load on a pallet to cover
and
contain the load. Stretch wrapping, whether accomplished by a turntable,
rotating
arm, vertical rotating ring, or horizontal rotating ring, typically covers the
four
vertical sides of the load with a stretchable packaging material such as
polyethylene packaging material. In each of these arrangements, relative
rotation
is provided between the load and a packaging material dispenser to wrap
packaging material about the sides of the load.
[004] Wrapping machines provide relative rotation between a packaging
material dispenser and a load either by driving the packaging material
dispenser
around a stationary load or rotating the load on a turntable. Upon relative
rotation,
packaging material is wrapped on the load. Rotating ring wrapping machines
generally include a roll of packaging material mounted in a dispenser, which
rotates
about the load on a rotating ring. Rotating rings are categorized as vertical
rotating

-1-


CA 02787780 2012-07-20
WO 2011/091258 PCT/US2011/022066
rings or horizontal rotating rings. Vertical rotating rings move vertically
between an
upper and lower position to wrap packaging material around a load. In a
vertical
rotating ring apparatus, as in turntable and rotating wrap arm apparatuses,
the four
vertical sides of the load are wrapped, along the height of the load.
Horizontal
rotating rings are stationary and the load moves through the rotating ring,
usually
on a conveyor, as the packaging material dispenser rotates around the load to
wrap
packaging material around the load. In a horizontal rotating ring apparatus,
the
length of the load is wrapped. As the load moves through the rotating ring and
off
the conveyor, the packaging material slides off a conveyor (the surface
supporting
the load) and into contact with the load.
[005] Historically, wrappers have suffered from packaging material breaks
and limitations on the amount of force applied to the load (as determined in
part by
the amount of pre-stretch used) due to erratic speed changes required to wrap
"non-square" loads, such as narrow, tall loads, short, wide loads, and short,
narrow
loads. The non-square shape of such loads often results in the supply of
excess
packaging material during the wrapping cycle, during time periods in which the
demand rate for packaging material by the load is exceeded by the supply rate
of
the packaging material by the packaging material dispenser. This leads to
loosely
wrapped loads. In addition, when the demand rate for packaging material by the
load is greater than the supply rate of the packaging material by the
packaging
material dispenser, breakage of the packaging material may occur.
[006] When wrapping a typical rectangular load, the demand for packaging
material varies, decreasing as the packaging material approaches contact with
a
corner of the load and increasing after contact with the corner of the load.
When
wrapping a non-square load, the variation in the demand rate is even greater
than
in a typical rectangular load. In vertical rotating rings, high speed rotating
arms,
and turntable apparatuses, the variation is caused by a difference between the
length and the width of the load. In a horizontal rotating ring apparatus, the
variation is caused by a difference between the height of the load (distance
above
the conveyor) and the width of the load. Variations in demand may make it
difficult
to properly wrap the load. The problem with variations is exacerbated when
wrapping a load having one or more dimensions that may differ from one or more
corresponding dimensions of a preceding load. The problem may also be

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CA 02787780 2012-07-20
WO 2011/091258 PCT/US2011/022066
exacerbated when wrapping a load having one or more dimensions that vary at
one
or more locations of the load itself.
[007] The amount of force, or pull, that the packaging material exhibits on
the load determines how tightly and securely the load is wrapped.
Conventionally,
this wrap force is controlled by controlling the feed or supply rate of the
packaging
material dispensed by the packaging material dispenser, for example, the wrap
force of many known commercially available stretch wrapping machines is
controlled by attempting to alter the supply of packaging material such that a
relatively constant packaging material wrap force is maintained. With powered
pre-
stretching devices, changes in the force or tension of the dispensed packaging
material were monitored. This has been accomplished using feedback
mechanisms typically linked to spring loaded dancer bars, electronic load
cells, or
torque control devices. The changing force or tension on the packaging
material
caused by rotating a rectangular shaped load is transmitted back through the
packaging material to some type of sensing device which attempts to vary the
speed of the motor driven dispenser to minimize the change. The passage of the
corner causes the force or tension of the packaging material to increase. This
increase is typically transmitted back to an electronic load cell, spring-
loaded
dancer interconnected with a sensing means, or to a torque control device.
After
the corner is passed, the force or tension on the packaging material reduces.
This
reduction is transmitted back to some device that in turn reduces the
packaging
material supply to attempt to maintain a relatively constant wrap force or
tension.
[008] With the ever faster wrapping rates demanded by the industry, the
rotation speeds have increased significantly to a point where the concept of
sensing changes in force and altering supply speed in response loses
effectiveness. The delay of response has been observed to begin to move out of
phase with rotation at approximately 20 RPM. The actual response time for the
rotating mass of packaging material roll and rollers approximating 100 lbs
must shift
from accelerate to decelerate eight times per revolution, that at 20 RPM, is a
shift
more than every half second.
[009] Even more significant is the need to minimize the acceleration and
deceleration times for these faster cycles. Initial acceleration must pull
against
clamped packaging material, which typically cannot stand a high force,
especially
the high force of rapid acceleration that cannot be maintained by the feedback
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CA 02787780 2012-07-20
WO 2011/091258 PCT/US2011/022066
mechanisms described above. Use of high speed wrapping has therefore been
limited to relatively lower wrap forces and pre-stretch levels where the loss
of
control at high speeds does not produce undesirable packaging material breaks.
[010] Packaging material dispensers mounted on rotating rings present
additional special issues concerning effectively wrapping at high speeds. Many
commercially available rotating ring wrappers that are in use depend upon
electrically powered motors to drive the pre-stretch packaging material
dispensers.
The power for these motors must be transmitted to the rotating ring. This is
typically done through electric slip rotating rings mounted to the rotating
ring with an
electrical pick up fingers mounted to the fixed frame. Alternately others have
attempted to charge a battery or run a generator during rotation. All of these
devices suffer complexity, cost and maintenance issues. But even more
importantly they add significant weight to the rotating ring which impacts its
ability to
accelerate and/or decelerate rapidly. Packaging material dispensers mounted on
vertical rotating rings have the additional problem of gravity forces added to
centrifugal forces of high-speed rotation.
[011] Accordingly, it is an object of the present disclosure to provide
methods and apparatuses to overcome one or more of the above-identified
disadvantages.

SUMMARY OF THE DISCLOSURE

[012] According to one aspect of the present disclosure, a method and
apparatus for dispensing packaging material to be wrapped around a load is
provided. The apparatus may include a packaging material dispenser including
one or more packaging material dispensing rollers. The packaging material
dispensing roller(s) may be driven to dispense packaging material by a
rotational
drive system through a mechanical connection operatively coupling the
packaging
material dispensing roller(s) and the rotational drive system.
[013] According to one aspect of the present disclosure, during at least a
portion of a wrapping cycle, control of a mechanical connection operatively
coupling
a rotational drive system and a packaging material dispenser may be based at
least
in part on instantaneous demand for packaging material at the load. As used
herein, the term "demand" may be defined as the quantity of packaging material
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needed to wrap at least a portion of the load to achieve a desired wrap force
and/or
containment force sufficient to meet containment needs of the load. As used
herein, wrap force is defined as the force exerted on the load by an
individual web
of film applied to the load. As used herein, containment force is defined as
the
force exerted on the load by cumulative layers of film. The containment force
may
be generated by the wrap forces exerted on the load by multiple layers of
film. The
term "instantaneous demand" may be defined as the demand for packaging
material at a load at a particular instant. For a wrapping apparatus with a
packaging material dispenser that rotates around a stationary load, the
instantaneous demand may be represented by a line extending perpendicularly
from the rotational axis of the packaging material dispenser to a plane
defined by a
surface of a length of packaging material that extends between the packaging
material dispenser and the load. For a wrapping apparatus with a rotating
load,
instead of a rotating packaging material dispenser, the instantaneous demand
may
be represented by a line extending perpendicularly from the rotational axis of
the
load to the plane. Additionally or alternatively, the instantaneous demand may
be
represented by a line extending radially from the rotational axis of the
packaging
material dispenser to a point on the surface of the load (for a rotating
packaging
material dispenser), or by a line extending radially from the rotational axis
of the
load to a point on the surface of the load (for a rotating load).
[014] For example, as shown in FIG. 5, when the packaging material
dispenser is in the position shown while wrapping a bottom portion of the
load, the
instantaneous demand at that instant may be represented by R1. When the
packaging material dispenser is in the position shown while wrapping a middle
portion of the load, the instantaneous demand at that instant may be
represented
by R.2. Further, when the packaging material dispenser is in the position
shown
while wrapping a top portion of the load, the instantaneous demand at that
instant
may be represented by R3. Thus, it should be understood that for wrapping a
load
like the one shown in FIG. 5, the instantaneous demand may change during
wrapping as the characteristics of the portion of the load being wrapped
change.
The varying profile of the load in FIG. 5 may be due to the load being
composed of
units that have different dimensions, girths, and/or shapes, that may be
stacked
together to form the load.

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[015] FIG. 8 shows representations of instantaneous demand for top,
middle, and bottom portions of an irregularly shaped load when the packaging
material dispenser is in the position shown. The instantaneous demand while
wrapping the top portion may be represented by R4, the instantaneous demand
while wrapping the middle portion may be represented by R5, and the
instantaneous demand while wrapping the bottom portion may be represented by
R6.
[016] Even during portions of the wrapping cycle where the characteristics
of the portion of the load being wrapped do not change, the instantaneous
demand
may change. For example, in FIG. 6, as the packaging material dispenser is
wrapping the bottom portion of the load, when the packaging material dispenser
is
in the position shown, the instantaneous demand may be represented by R1. If
the
packaging material dispenser rotates in the counterclockwise direction, at a
new
position the instantaneous demand may be represented by a line R1'. R1' is
shorter than R1, thus indicating that the instantaneous demand decreased as
the
packaging material dispenser traveled from the position shown to the new
position.
The instantaneous demand decreased even though the characteristics of the
bottom portion of the load did not change. The change in instantaneous demand
is
due to the shape of the bottom portion of the load. The instantaneous demand
will
increase when the length of packaging material between packaging material
dispenser and the load contacts a corner of the load, and may continue to
increase
for a period of time thereafter. However, as the length of the packaging
material
moves toward a face of load, the instantaneous demand will begin to decrease
until
the next corner is encountered.
[017] Instantaneous demand can also be represented using by a distance
from a suitable location, such as a point on the packaging material dispenser,
to the
load. Such distances are shown in FIG. 9. The distance may change during
relative rotation between the packaging material dispenser and the load.
[018] By controlling the mechanical connection operatively coupling the
rotational drive system and the packaging material dispenser based at least in
part
on the instantaneous demand, adjustments can be made in response to the
variations described above. By making such adjustments, it may be possible to
reduce costs by decreasing the likelihood of film breaks and ensuring that
excess
packaging material is not dispensed; wrap a wide variety of loads regardless
of

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shape and/or size, or placement on a load wrapping surface; and improve
throughput by allowing adjustments to settings to be made automatically. It
may
also be possible to obtain a more consistently wrapped load, since a selected
payout percentage may be maintained for at least a portion of a wrapping
cycle,
and/or from one wrapping cycle to the next.
[019] As used herein, the phrase "payout percentage" is defined as a ratio
of the amount of packaging material dispensed for at least a portion of a
wrapping
cycle to the demand for packaging material at the load for that same portion
of the
wrapping cycle. The payout percentage may be calculated or expressed in
different ways. The payout percentage may be expressed as the percent of
packaging material dispensed relative to at least a portion of load girth. For
example, the payout percentage may be expressed as the percent of packaging
material dispensed divided by load girth, wherein the packaging material
dispensed
is the amount for a full relative revolution between the packaging material
dispenser
and the load. Additionally or alternatively, the payout percentage may be
expressed as the percent of packaging material dispensed divided by a portion
of
the load girth, wherein the packaging material dispensed is the amount for a
portion
of the relative revolution during which the portion of the load girth is
wrapped. The
portion of the load girth may be, for example, a portion between points A and
B in
FIG. 5, in which case the portion of the relative revolution is the half of
the relative
revolution during which the portion between points A and B is wrapped, and the
packaging material dispensed for purposes of determining the payout percentage
is
the amount dispensed during that half of the relative revolution. The location
of
points A and B are intended to be exemplary only and points A and B may be
located anywhere along the girth (perimeter) of the load.
[020] For example, if the length of packaging material dispensed is 100
inches, and the demand for packaging material at the load is 100 inches, then
the
payout percentage equals 100%. If the length of packaging material dispensed
during a relative revolution is 130 inches, and the girth of the load is 100
inches,
then the payout percentage equals 130%. Test results have shown that good
wrapping performance in terms of load containment (wrap force), optimum
packaging material use (efficiency), and avoiding film breaks, is obtained at
a
payout percentage that is between approximately 75% and approximately 130%,
preferably between approximately 85% and approximately 120%, and more
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preferably between approximately 95% and approximately 115%. Factors that may
affect the results may include, for example, an amount the film is pre-
stretched, the
elasticity of the film, film gauge, film width, film quality, and gel level.
[021] The payout percentage may be selected based on the desired wrap
force and/or containment force. For example, the payout percentage may be
selected to produce a desired wrap force and/or containment force that may be
sufficient to meet the containment needs of a load. The containment needs of a
load may depend on the types of forces the load is exposed to during
transport.
Additionally or alternatively, the payout percentage may be selected based on
the
type of load being wrapped, taking into account factors, such as, the
stability of the
load, the crushability of the load, and/or any other suitable factors.
Decreasing the
payout percentage may cause the wrap force exerted by the packaging material
on
the load to increase (assuming other factors affecting wrap force remain
constant),
while increasing the payout percentage may cause the wrap force to decrease
(assuming other factors affecting wrap force remain constant). The containment
force may be generated by the wrap forces exerted on the load by multiple
layers of
film. A user may select payout percentages by setting or adjusting a force
exerting
mechanism operatively coupled to the mechanical connection that operatively
couples the rotational drive system to the packaging material dispenser. It
should
be understood that a user may also select settings that correspond to a payout
percentage without actually taking the payout percentage into consideration.
For
example, the user may select settings that are likely to produce good wrapping
performance without actually having calculated the payout percentage, or
considered values related to the payout percentage, to make the selection. The
user may instead have selected the settings after, for example, experimenting
with
other settings, considering settings that produced good wrapping performance
in
the past, and/or selected the settings at random. To the extent that those
settings
are elements/indicators of payout percentage, by selecting those settings, the
user
will have selected a payout percentage.
[022] As used herein, the phrase "selected payout percentage" can be
defined as a payout percentage at which a wrap force and/or containment force
is
achieved that is sufficient to meet the containment needs of a load, a range
of
payout percentages at which the wrap forces and/or containment forces achieved
are within a range of values capable of meeting the containment needs of a
load,
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and/or a range of payout percentages that are within a range of 10%,
preferably
7%, and more preferably 5% or less, of the payout percentage or range of
payout
percentages at which the containment needs of the load are met.
[023] In accordance with one aspect of the disclosure, an apparatus for
wrapping a load with packaging material may include a packaging material
dispenser for dispensing packaging material. The apparatus may also include a
relative rotation assembly for providing relative rotation between the load
and the
packaging material dispenser. The apparatus may further include a mechanical
connection operatively coupling the packaging material dispenser to the
relative
rotation assembly. The relative rotation assembly may be configured to drive
the
packaging material dispenser through the mechanical connection. The apparatus
may further include a force exerting mechanism operatively coupled to the
mechanical connection. The apparatus may further include a sensing element
configured sense a characteristic of dispensed packaging material. The sensing
element may be operatively coupled to the mechanical connection. The force
exerting mechanism and the sensing element may be configured to control the
mechanical connection to maintain a selected ratio of packaging material
dispensed to demand for packaging material at the load for at least a portion
of a
wrap cycle.
[024] According to another aspect of the present disclosure, an apparatus
for wrapping a load with packaging material may include a packaging material
dispenser for dispensing packaging material. The apparatus may also include a
relative rotation assembly for providing relative rotation between the load
and the
packaging material dispenser. The apparatus may further include a mechanical
connection operatively coupling the packaging material dispenser to the
relative
rotation assembly. The relative rotation assembly may be configured to drive
the
packaging material dispenser through the mechanical connection. The apparatus
may further include a sensing element configured to sense a change in demand
for
packaging material at the load and adjust the mechanical connection in
response to
the change in demand to maintain a ratio of packaging material dispensed to
demand in a selected range for at least a portion of a wrap cycle.
[025] According to yet another aspect of the present disclosure, a method
for wrapping a load with packaging material may include providing relative
rotation
between a packaging material dispenser and the load with a relative rotation
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assembly. The method may also include driving the packaging material dispenser
to dispense packaging material with the relative rotation assembly through a
mechanical connection operatively coupling the packaging material dispenser
and
the relative rotation assembly. The method may further include engaging a
portion
of the packaging material extending between the packaging material dispenser
and
the load with a sensing element. A change of position of the sensing element
may
be indicative of a change in demand for packaging material at the load. The
method may further include adjusting the mechanical connection based at least
in
part on movement of the sensing element to maintain a ratio of packaging
material
dispensed to demand in a selected range for at least a portion of a wrap
cycle.
[026] According to yet another aspect of the present disclosure, a method
for wrapping a load with packaging material may include providing relative
rotation
between a packaging material dispenser and the load with a relative rotation
assembly. The method may also include driving the packaging material dispenser
to dispense packaging material with the relative rotation assembly through a
mechanical connection operatively coupling the packaging material dispenser
and
the relative rotation assembly. The method may further include controlling the
mechanical connection with a sensing element operatively coupled to the
mechanical connection. The method may further include engaging a portion of
the
packaging material extending between the packaging material dispenser and the
load with the sensing element to monitor tension of the packaging material.
The
method may further include moving the sensing element to control the
mechanical
connection to maintain an amount of packaging material dispensed relative to
the
demand for packaging material at the load in a selected range for at least a
portion
of a wrapping cycle.
[027] According to yet another aspect of the present disclosure, a method
for wrapping a load with packaging material may include providing relative
rotation
between a packaging material dispenser and the load with a relative rotation
assembly. The method may also include driving the packaging material dispenser
to dispense packaging material with the relative rotation assembly through a
mechanical connection operatively coupling the packaging material dispenser
and
the relative rotation assembly. The method may further include engaging a
portion
of the packaging material extending between the dispensing assembly and the
load
with a sensing element operatively coupled to a control element of the
mechanical
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connection. The method may further include exerting a force on the control
element with an adjustable force exerting mechanism. The method may further
include controlling the mechanical connection with the control element,
through
positioning of the sensing element and the force exerted by the adjustable
force
exerting mechanism, to maintain a ratio of packaging material dispensed
relative to
demand for packaging material at the load substantially constant for at least
a
portion of a wrap cycle.
[028] According to yet another aspect of the present disclosure, an
apparatus for stretch wrapping a load may include a packaging material
dispenser
for dispensing packaging material. The packaging material dispenser may
include
a dispensing assembly for pre-stretching the packaging material. The apparatus
may also include a relative rotation assembly for providing relative rotation
between
the load and the packaging material dispenser. The apparatus may further
include
a mechanical connection operatively coupling the dispensing assembly to the
relative rotation assembly. The relative rotation assembly may be configured
to
drive the dispensing assembly through the mechanical connection. The apparatus
may further include a sensing roller configured to sense a change in demand
for
packaging material at the load, and move to adjust the mechanical connection
in
response to the change in packaging material demand. The apparatus may further
include an adjustable force exerting mechanism operatively coupled to the
sensing
roller. The adjustable force exerting mechanism may be configured to control
movement of the sensing roller.
[029] According to yet another aspect of the present disclosure, an
apparatus for wrapping a load with packaging material may include a packaging
material dispenser for dispensing packaging material. The apparatus may also
include a relative rotation assembly for providing relative rotation between
the load
and the packaging material dispenser. The apparatus may further include a
mechanical connection operatively coupling the packaging material dispenser to
the relative rotation assembly. The relative rotation assembly may be
configured to
drive the packaging material dispenser through the mechanical connection. The
apparatus may further include a force exerting mechanism operatively coupled
to
the mechanical connection. The apparatus may further include a sensing element
configured sense a characteristic of dispensed packaging material. The sensing
element may be operatively coupled to the mechanical connection. The force

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exerting mechanism and the sensing element may be configured to control the
mechanical connection to maintain a wrap force exerted by the dispensed
packaging material on the load in a selected force range for at least a
portion of a
wrap cycle.
[030] Additional objects and advantages of the disclosure will be set forth in
part in the description which follows, and in part will be obvious from the
description, or may be learned by practice of the disclosure. The objects and
advantages of the disclosure will be realized and attained by means of the
elements and combinations particularly pointed out in the appended claims.
[031] It is to be understood that both the foregoing general description and
the following detailed description are exemplary and explanatory only and are
not
restrictive of the disclosure, as claimed.
[032] The accompanying drawings, which are incorporated in and constitute
a part of this specification, illustrate embodiments of the disclosure and
together
with the description, serve to explain the principles of the disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

[033] FIG. 1 is an isometric view of a wrapping apparatus for wrapping a
load, according to one aspect of the present disclosure;
[034] FIG. 2 is an isometric view of a roll carriage of the wrapping apparatus
of FIG. 1, according to one aspect of the present disclosure;
[035] FIG. 3 is an enlarged portion of the isometric view of the roll carriage
of FIG. 2;
[036] FIG. 4 is an isometric view of a support structure for the rotating ring
of a wrapping apparatus according to one aspect of the present disclosure;
[037] FIG. 5 is a top view of a roll carriage and a load, according to one
aspect of the present disclosure;
[038] FIG. 6 is a side view of the load of FIG. 5, according to the present
disclosure.
[039] FIG. 7 is an enlarged portion of the isometric view of the roll-
carriage
of FIG. 2;
[040] FIG. 8 is a top view of a roll carriage and a load, according to another
aspect of the present disclosure;

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[041] FIG. 9 is a top view of a roll carriage and a load, according to yet
another aspect of the present disclosure;
[042] FIG. 10 is an isometric view of a roll carriage of a wrapping apparatus,
according to another aspect of the present disclosure; and
[043] FIG. 11 is an enlarged portion of the isometric view of the roll
carriage
of FIG. 10.

DESCRIPTION OF THE EMBODIMENTS

[044] Reference will now be made in detail to the present embodiments of
the disclosure, examples of which are illustrated in the accompanying
drawings.
Wherever possible, the same reference numbers will be used throughout the
drawings to refer to the same or like parts.
[045] The disclosures of each of U.S. Patent No. 4,418,510, entitled
"STRETCH WRAPPING APPARATUS AND PROCESS," and filed April 17, 1981;
U.S. Patent No. 4,953,336, entitled "HIGH TENSILE WRAPPING APPARATUS,"
and filed August 17, 1989; U.S. Patent No. 4,503,658, entitled "FEEDBACK
CONTROLLED STRETCH WRAPPING APPARATUS AND PROCESS," and filed
March 28, 1983; U.S. Patent No. 4,676,048, entitled "SUPPLY CONTROL
ROTATING STRETCH WRAPPING APPARATUS AND PROCESS," and filed May
20, 1986; U.S. Patent No. 4,514,955, entitled "FEEDBACK CONTROLLED
STRETCH WRAPPING APPARATUS AND PROCESS," and filed April 6,1981;
U.S. Patent No. 6,748,718, entitled "METHOD AND APPARATUS FOR
WRAPPING A LOAD," and filed October 31, 2002; U.S. Patent Application
Publication No. 2006/0248858, entitled "METHOD AND APPARATUS FOR
DISPENSING A PREDETERMINED FIXED AMOUNT OF PRE-STRETCHED FILM
RELATIVE TO LOAD GIRTH," filed April 6, 2006; U.S. Patent Application
Publication No. 2007/0209324, entitled "METHOD AND APPARATUS FOR
SECURING A LOAD TO A PALLET WITH A ROPED FILM WEB," and filed
February 23, 2007; U.S. Patent Application Publication No. 2007/0204565,
entitled
"METHOD AND APPARATUS FOR METERED PRE-STRETCH FILM DELIVERY,"
and filed September 6, 2007; U.S. Patent Application Publication No.
2007/0204564, entitled "RING WRAPPING APPARATUS INCLUDING METERED
PRE-STRETCH FILM DELIVERY ASSEMBLY," and filed February 23, 2007; and

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U.S. Patent Application Publication No. 2009/0178374, entitled "ELECTRONIC
CONTROL OF METERED FILM DISPENSING IN A WRAPPING APPARATUS,"
and filed January 7, 2009, are incorporated herein by reference in their
entirety.
[046] The present disclosure is related to a method and apparatus for
dispensing packaging material to be wrapped around a load. In an exemplary
embodiment, packaging material is stretch wrap packaging material. As used
herein, stretch wrap packaging material is defined as material having a high
yield
coefficient to allow the material a large amount of stretch during wrapping.
However, it is possible that the apparatuses and methods disclosed herein may
be
practiced with packaging material that will not be pre-stretched prior to
application
to the load. Examples of such packaging material include netting, strapping,
banding, or tape. As used herein, the terms "packaging material," "film,"
"film web,"
"web," and "packaging material web" are interchangeable.
[047] According to one aspect of the present disclosure, a wrapping
apparatus 100 for wrapping packaging material 142 around a load 138, shown in
FIG. 1, may include a non-rotating frame 110 having four legs, 112a, 112b,
112c,
and 112d. A movable frame portion 118 may be connected to and movable on the
non-rotating frame 110. Movable frame portion 118 may include a support
portion
120, a rotatable ring 122, and a support structure 124, shown in FIGS. 2-4.
Support structure 124 may include, for example, a fixed (i.e., non-rotatable)
ring, a
curved portion that is discontinuous, one or more finger-type supports,
support
rollers, a belt supporting track, and/or any other suitable support structure
know in
the art. It is also contemplated that non-rotating frame 110, support portion
120,
rotatable ring 122, and support structure 124 may be similar to the non-
rotating
frame, support portion, rotatable ring, and fixed ring described in U.S.
Patent
Application Publication No. 2007/0204565, entitled "METHOD AND APPARATUS
FOR METERED PRE-STRETCH FILM DELIVERY," filed February 23, 2007, the
entire disclosure of which is incorporated herein by reference in its
entirety.
[048] A first drive belt 130, shown in FIGS. 1-3, driven by a motor 132, may
be positioned around an outer circumference of rotatable ring 122. Motor 132
rotates first drive belt 130 which in turn rotates rotatable ring 122. Thus,
motor 132
and first drive belt 130 form a rotational drive system 129. Alternatively,
rotatable
ring 122 can be frictionally driven by one or more suitably surfaced wheels
pressed
against its outer surface.

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[049] Wrapping apparatus 100 may include a roll carriage 144 similar to the
one described in U.S. Patent Application Publication No. 2007/0204565, filed
February 23, 2007, the entire disclosure of which is incorporated herein by
reference in its entirety. Roll carriage 144 may be mounted on rotatable ring
122.
Roll carriage 144 and rotatable ring 122 may rotate about a vertical axis 158
(FIG.
1) as moveable frame portion 118 moves up and down the non-rotating frame 110
to spirally wrap packaging material 142 about a load 138. A motor 136 may be
provided to raise and/or lower movable frame portion 118 on non-rotating frame
110. Load 138 can be manually placed in the wrapping area or conveyed into the
wrapping area by a conveyor (not shown). As shown in FIGS. 1-3, roll carriage
144
may be mounted underneath and outboard of rotatable ring 122, thus maximizing
wrapping space. Roll carriage 144 may include a packaging material dispenser
140, as shown in FIGS. 1-3, 5, and 8-11. Packaging material dispenser 140 may
include a dispensing assembly 160 configured to dispense a sheet or web of
packaging material 142.
[050] Dispensing assembly 160 may be driven to dispense packaging
material 142 by rotational drive system 129, through a path 131 and a
mechanical
connection 133 operatively connecting rotational drive system 129 and
dispensing
assembly 160. Path 131 may include a second drive belt 134, shown in FIGS. 1-
4.
Second drive belt 134 may be supported by support structure 124. For example,
second drive belt 134 may be positioned around the outer circumference of
support
structure 124. Second drive belt 134 may include a fixed belt, drive chain, or
other
suitable device, that does not rotate. Additionally or alternatively, a
rotatable or
non-rotatable drive ring may be provided, and may be supported by support
structure 124. Additionally or alternatively, path 131 may include components
similar to those disclosed in U.S. Patent Application Publication No.
2007/0204565,
entitled "METHOD AND APPARATUS FOR METERED PRE-STRETCH FILM
DELIVERY," and filed September 6, 2007, incorporated herein by reference in
its
entirety, to link a relative rotation assembly and a dispensing assembly of a
packaging material dispenser.
[051] Mechanical connection 133 may include, for example, a mechanical
ratio control 192 operatively coupled to path 131 and dispensing assembly 160.
As
shown in FIGS. 2 and 3, mechanical ratio control 192 may include a variable
transmission such as, for example, a hydrostatic transmission 200. One
exemplary
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such hydrostatic transmission is made by Hydrogear, model number BDR-31 1.
Hydrostatic transmission 200 may be supported on roll carriage 144, and may
include a rotatable input shaft 202 and a rotatable output shaft 204. A series
of
hydraulic pumps and valves (not shown) are used to set the ratio between the
input
and the output of hydrostatic transmission 200. This ratio may be set and
adjusted
as desired. The hydraulic pumps and valves set the ratio based on fluid flow
in
hydrostatic transmission 200, rather than based on fluid pressure in
hydrostatic
transmission 200.
[052] Second drive belt 134 may engage rotatable input shaft 202 of
hydrostatic transmission 200. Rotatable input shaft 202 of hydrostatic
transmission
200 may engage second drive belt 134 through gear teeth or any other suitable
mode of engagement.
[053] Although a hydrostatic transmission is used in the exemplary
embodiment, any other appropriate mechanical power transmissions may be used
to control the input/output ratio. Further, other suitable mechanical controls
such
as, for example, a split sheave, variable pitch belt sheaves, fixed center and
adjustable center sheaves, wider range variable pitch belt drives, cone and
ring
variable speed drives, rolling ring variable speed drives, and ball and ring
variable
speed drives may be used to control the input/output ratio. Alternatively,
methods
such as a moving a second ring with the differential between the rings
generating
the output, moving second drive belt 134 with the differential between second
drive
belt '134 and rotatable ring 122 generating the output, using a differential
and
controlling one output to adjust another output, and an electric motor without
load
cell feedback may be used.
[054] Dispensing assembly 160 may be configured to pre-stretch packaging
material 142 before it is applied to load 138 if pre-stretching is desired, or
to
dispense packaging material 142 to load 138 without pre-stretching. Dispensing
assembly 160 may include a packaging material dispensing roller, such as a
downstream dispensing roller 164, or a plurality of packaging material
dispenser
rollers, such as an upstream dispensing roller 162 and downstream dispensing
roller 164. It is also contemplated that dispensing assembly 160 may include
an
assembly of pre-stretch rollers and idle rollers, similar to those described
in U.S.
Patent Application Publication Nos. 2006/0248858, 2007/0204565, 2007/0204564,
and 2009/0178374, the disclosures of which are incorporated herein by
reference
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in their entirety. Additional or fewer rollers may be used as desired. In one
exemplary embodiment, each of upstream and downstream dispensing rollers 162,
164 may preferably be the same size, and each may have, for example, an outer
diameter of approximately 2.5 inches. Upstream and downstream dispensing
rollers 162, 164 should have a sufficient length to carry a twenty inch wide
web of
packaging material 142 along their working lengths. It is contemplated that,
in one
exemplary embodiment, rollers used for conventional conveyors may be used to
form upstream and downstream dispensing rollers 162, 164.
[055] The terms "upstream" and "downstream," as used in this application,
are intended to define positions and movement relative to the direction of
flow of
packaging material 142 as it moves from packaging material dispenser 140 to
load
138. Movement of an object toward packaging material dispenser 140, away from
load 138, and thus, against the direction of flow of packaging material 142,
may be
defined as "upstream." Similarly, movement of an object away from packaging
material dispenser 140, toward load 138, and thus, with the flow of packaging
material 142, may be defined as "downstream." Also, positions relative to load
138
and packaging material dispenser 140 may be described relative to the
direction of
packaging material flow. For example, when two dispensing rollers are present,
the
dispensing roller closer to packaging material dispenser 140 may be
characterized
as the "upstream" roller and the dispensing roller closer to load 138 and
further
from packaging material dispenser 140 may be characterized as the "downstream"
roller.
[056] The surfaces of upstream dispensing roller 162 and downstream
dispensing roller 164 may either be coated or uncoated depending on the type
of
application in which wrapping apparatus 100 is being used. Upstream and
downstream dispensing rollers 162, 164 may be mounted on roller shafts 166 and
168, respectively. Roller shafts 166 and 168 may include, for example, hex
shafts.
Sprockets 170 and 172 may be located on the ends of the roller shafts 166 and
168, respectively, and may be configured to provide control over the rotation
of
roller shafts 166 and 168, and thus, upstream and downstream dispensing
rollers
162, 164. Upstream and downstream dispensing rollers 162, 164, may be
operatively connected to each other through a drive belt or chain 174
connecting
sprockets 170 and 172.

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[057] It is contemplated that upstream dispensing roller 162 and
downstream dispensing roller 164 may have different sized sprockets 170 and
172
so that the surface movement of upstream dispensing roller 162 may be slower
than that of downstream dispensing roller 164. For example, sprockets 170 and
172 may be sized so that the surface movement of upstream dispensing roller
162
is at least approximately 40% slower than that of downstream dispensing roller
164.
Sprockets 170, 172 may be sized depending on the amount of packaging material
elongation desired. Thus, the surface movement of upstream dispensing roller
162
can be about 40%, 75%, 200% or 300% slower than the surface movement of
downstream dispensing roller 164 to obtain pre-stretching of 40%, 75%, 200% or
300%. While pre-stretching normally ranges from 40% to 300%, excellent results
have been obtained when narrower ranges of pre-stretching are used, such as
pre-
stretching the material 40% to 75%, 75% to 200%, 200% to 300%, and at least
100%. In certain instances, pre-stretching has been successful at over 300% of
pre-stretch.
[058] Rapid elongation of packaging material 142 by upstream and
downstream dispensing rollers 162, 164, followed by rapid strain relief of
packaging
material 142, may cause a "memorization" effect. Due to this "memorization"
effect,
packaging material 142 may continue to shrink for some time after being
wrapped
onto load 138. Over time, packaging material 142 may significantly increase
its
holding force and conformation to load 138. This characteristic of packaging
material 142 may allow it to be used for wrapping loads at very close to zero
stretch
wrapping force, using the memory to build holding force and load conformity.
Some
embodiments of the present disclosure permit relative rotation between the
load
and dispenser at approximately 60 rpm. At this speed, the dispensed pre-
stretched
film has a tendency to billow around the load before contracting and/or
shrinking
onto the load such that the film contacts all sides and/or corners of the load
substantially simultaneously. This is particularly beneficial when dealing
with light,
crushable, or twistable loads.
[059] During operation of apparatus 100, motor 132 drives first drive belt
130, which in turn rotates rotatable ring 122, roll carriage 144 mounted on
rotatable
ring 122, and hydrostatic transmission 200 supported by roll carriage 144. As
hydrostatic transmission 200 rotates with ring 122, second drive belt 134 on
support
structure 124 engages rotatable input shaft 202 of hydrostatic transmission
200,
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causing rotatable input shaft 202 to rotate. Thus, second drive belt 134
translates
the rotational drive from rotatable ring 122 to input shaft 202 of hydrostatic
transmission 200. Using one or more pumps and/or valves, hydrostatic
transmission 200 converts movement of input shaft 202 into fluid flow toward
the
output of hydrostatic transmission 200, and converts the fluid flow into
movement of
output shaft 204. Since hydrostatic transmission 200 operates based on fluid
flow,
rather than based on fluid pressure, the lag time associated with building up
fluid
pressure and/or decreasing fluid pressure, to create a desired output, may be
avoided. Instead, by operating based on fluid flow, hydrostatic transmission
200
can provide an immediate response of output shaft 204 due to movement of input
shaft 202.
[060] The output of hydrostatic transmission 200, via rotatable output shaft
204, drives downstream dispensing roller 164, and through connection 174,
upstream dispensing roller 162. As upstream and downstream dispensing rollers
162, 164 rotate, packaging material 142 flows downstream from packaging
material
roll 152 through dispensing assembly 160. By using second drive belt 134 to
drive
dispensing assembly 160 off of rotatable ring 122, and thus, rotational drive
system
129, it is possible to eliminate the conventional motor that drives known
packaging
material dispensers, as well the conventional control box, greatly reducing
the
weight of packaging material dispenser 140. By providing a mechanical
connection
between the rotational drive system and dispensing assembly 160, the need for
placing electrical power sources or connections on rotatable ring 122 for
electrically
powering the dispensing assembly 160 may be eliminated. It is contemplated
that
the mechanical connection may be entirely mechanical, devoid of any components
that operate using electrical power, or at least partially mechanical, with
one or
more components that operate using electrical power, including, for example, a
servocontrol device.
[061] The rotation of rotatable output shaft 204 drives downstream
dispensing roller 164. Connection 174 between the upstream and downstream
dispensing rollers 162, 164 causes upstream dispensing roller 162 to rotate as
downstream dispensing roller 164 rotates, thus dispensing packaging material
142.
Engagement between rotatable output shaft 204 and downstream dispensing roller
164 may include, for example, drive belts, gears, chains, and/or any other
suitable
devices configured to convert rotation of rotatable output shaft 204 into
rotation of
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upstream and downstream dispensing rollers 162, 164. In the exemplary
embodiment, hydrostatic transmission 200 may have a ninety degree angle
between its rotatable input shaft 202 and its rotatable output shaft 204.
[062] Hydrostatic transmission 200 may be set to control a ratio of the
relative rotational speed to dispensing speed by controlling a ratio of drive
input to
drive output. The speed at which rotatable input shaft 202 rotates, based on
the
speed at which rotational drive system 129 rotates rotatable ring 122 and roll
carriage 144, may be considered the input. The series of pumps and valves
contained within hydrostatic transmission 200 transmit the input from
rotatable input
shaft 202 to rotatable output shaft 204 using fluid flow, adjusting the
rotational
speed of rotatable output shaft 204 based on the input/output ratio of
hydrostatic
transmission 200. The input/output ratio of hydrostatic transmission 200 may
be
selectively and variably adjusted. As the input/output ratio decreases, the
relative
speed of the output shaft 204 increases, and the rotational speed of upstream
and
downstream dispensing rollers 162, 164 increases proportionally. The increased
rotational speed of upstream and downstream dispensing rollers 162, 164 causes
an increase in the supply/dispensing rate of packaging material 142. If, on
the
other hand, the input/output ratio increases, then the speed of the rotational
output
shaft 204 decreases, and the relative rotational speed of upstream and
downstream dispensing rollers 162, 164 decreases proportionally, resulting in
a
decrease in the supply/dispensing rate of packaging material 142. Thus, it
should
be apparent that while rotatable ring 122 and the rotatable input shaft may
rotate at
substantially the same speed, the rotational speed of rotatable output shaft
204,
and consequently the rotational speed of upstream and downstream dispensing
rollers 162, 164, may vary depending on the input/output ratio setting of
hydrostatic
transmission 200.
[063] The input/output ratio setting of hydrostatic transmission 200 may be
selectively and variably adjusted by a transmission lever 206 or other
suitable
control element operatively coupled to hydrostatic transmission 200. The
orientation of transmission lever 206 may affect the input/output ratio of
hydrostatic
transmission 200. That is, changing the position of transmission lever 206 may
change the input/output ratio of hydrostatic transmission 200. This adjustment
of
the input/output ratio may be accomplished, for example, by controlling a
valve
positioned between an input pump and an output pump in hydrostatic
transmission
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200. Rotation of transmission lever 206 in a first direction may decrease the
input/output ratio by increasing fluid flow between the input and output sides
of
hydrostatic transmission 200. Continued rotation of transmission lever 206 in
the
first direction may bring transmission lever 206 into a first position, where
substantially all of the input at rotatable input shaft 202 may be transmitted
or
translated to rotatable output shaft 204. Rotation of transmission lever 206
in a
second direction may increase the input/output ratio by decreasing the fluid
flow
between the input and output sides of hydrostatic transmission 200. Continued
rotation of transmission lever 206 in the second direction may bring
transmission
lever to a second position, where transmission or translation of the input at
rotatable input shaft 202 to rotatable output shaft 204 is prevented. When
input at
rotatable input shaft 202 is prevented from being transmitted/translated to
rotatable
output shaft 204, hydrostatic drive 200 is essentially in a neutral state
wherein
rotation of rotatable input shaft 202 is not transmitted to rotatable output
shaft 204.
In that state, rotatable input shaft 202 may rotate freely and independently
of
rotatable output shaft 204, and rotatable output shaft 204 may stop rotating.
[064] The use of hydrostatic transmission 200 may provide advantages.
One advantage is the input/output ratio of hydrostatic transmission 200 is
infinitely
or continuously variable in a range defined by the first and second positions
of
transmission lever 206. Thus, since hydrostatic transmission 200 is used to
control
dispensing of packaging material 142 through its connection to downstream
dispensing roller 164, hydrostatic transmission 200 allows for fine tuning of
how
much packaging material 142 is dispensed during at least a portion of a wrap
cycle,
that cannot be achieved with conventional gear and sprocket assemblies, which
typically operate at only a few discrete states. Another advantage is that
hydrostatic transmission 200 is highly sensitive, in that only about two to
three
pounds of force may be required to move transmission lever 206 between its
first
and second positions. Thus, hydrostatic transmission 200 may respond to
smaller
changes in the force on packaging material 142 than conventional gear and
sprocket assemblies. Yet another advantage is that hydrostatic transmission
200
can offer instantaneous power to rotate downstream dispensing roller 164, and
if
pre-stretching is desired, upstream dispensing roller 162. For example, if
hydrostatic drive 200 is in neutral, input shaft 202 may continue to rotate
due to its
movement relative to second drive belt 134, while output shaft 204 may receive
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none of the power from input shaft 202. However, as soon as transmission lever
206 begins to move in the first direction (away from neutral), the power from
the
already rotating input shaft 202 is immediately available, and may
instantaneously
be transmitted to output shaft 204 for use by upstream and downstream
dispensing
rollers 162, 164 to dispense packaging material 142. The immediately
availability
of the power from input shaft 202 is due to hydrostatic transmission 200 using
fluid
flow, as opposed to fluid pressure, to transmit power to output shaft 204,
since
systems that use fluid pressure require lag time in order for the fluid
pressure to
build and/or release to achieve a desired output. Moreover, changes in power
transmission between input shaft 202 and output shaft 204 may occur smoothly
as
the valve in hydrostatic transmission 200 opens and closes, ensuring smooth
wrapping, and reducing chatter associated with conventional gear and sprocket
assemblies.
[065] While the position of transmission lever 206 may dictate the
input/output ratio of hydrostatic transmission 200, a sensing element 194 may
move
transmission lever 206, causing a change in the position of transmission lever
206,
and thus, sensing element 194 may affect change in the input/output ratio of
hydrostatic transmission 200. Sensing element 194 may be operatively coupled
to
transmission lever 206 through a series of linkages 197. Sensing element 194
may
include a sensing roller 195 mounted for rotation on a shaft 212. Sensing
roller 195
may have an outer diameter of, for example, approximately 2.5 inches, and may
have a sufficient length to carry a twenty inch wide web of packaging material
142
along its working length. Sensing roller 195 may have other dimensions as
appropriate. In one embodiment, bearings for supporting shaft 212 may be press-

fit or welded into each end of sensing roller 195, and shaft 212 may be placed
therethrough, such that shaft 212 may be centrally and axially mounted through
the
length of sensing roller 195. A first end of shaft 212 may extend through a
slot 214
in a lower frame portion 216 of roll carriage 144, and may be pivotally
attached to
an upper support plate 218 of roll carriage 144. Additionally, shaft 212 may
be
cantilevered, such that a second end of the shaft may hang freely.
Consequently,
sensing roller 195 may have the ability to swing back and forth between an
extended position (generally away from dispensing assembly 160) and a
retracted
position (generally toward dispensing assembly 160). Alternatively, it is
contemplated that sensing element 194 may include a bar (not shown) pivotally

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attached to roll carriage 144, over which packaging material 142 may slide, an
assembly including one or more wheels (not shown), mounted on shaft 212 and
configured to engage packaging material 142, and/or any other suitable devices
for
engaging packaging material 142. Sensing element 194 may be configured to
sense one or more characteristics of packaging material 142, including, for
example, the tension force exerted on sensing element 194 by packaging
material
142, the orientation of packaging material 142 relative to load 138, and/or
any other
suitable characteristics.
[066] The swinging movement of sensing element 194 may rotate
transmission lever 206 through linkages 197. As sensing element 194 swings
toward its extended position, transmission lever 206 may rotate in its second
direction, the one that increases the input/output ratio of hydrostatic
transmission
200. This may cause the relative rotational speed of upstream and downstream
dispensing rollers 162, 164 to decrease proportionally, resulting in a
decrease in
the supply rate of packaging material 142. As sensing element 194 swings
toward
its retracted position, transmission lever 206 may rotate in its first
direction, the one
that decreases the input/output ratio of hydrostatic transmission 200. This
may
cause the relative rotational speed of upstream and downstream dispensing
rollers
162, 164 to increase proportionally, resulting in an increase in the supply
rate of
packaging material 142. Thus, the angular orientation of sensing element 194
may
affect the amount of film dispensed during at least a portion of a revolution
of roll
carriage 144 relative to load 138. As described below, a force exerting
mechanism
181 and tension in packaging material 142 may affect the angular orientation
of
sensing element 194, and thus, also may affect the amount of film dispensed
during the at least a portion of the revolution.
[067] Force exerting mechanism 181 may include a spring device 183. As
shown in FIG. 7, a first end 184 of spring device 183 may be coupled to shaft
212
of sensing element 194. A second end 186 of spring device 183 may be coupled
to
a frame portion 185. Frame portion 185 may extend from lower frame portion
216.
Spring device 183 may exert a force on shaft 212 in a direction that moves
sensing
element 194 toward its extended position. Thus, unless it is overcome by a
greater
opposing force, the force exerted by spring device 183 will pull sensing
element
194 toward its extended position.

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[068] During normal operation of wrapping apparatus 100, tension in
packaging material 142 may exert a force on sensing element 194 in a direction
that moves sensing element 194 toward its retracted position. Thus, unless it
is
countered by a greater opposing force, the tension force exerted by packaging
material 142 will pull sensing element 194 towards it retracted position.
Accordingly, the force exerted by spring device 183 and the tension force
exerted
by packaging material 142 may oppose one another.
[069] The instantaneous demand and the tension force exerted by
packaging material 142 on sensing element 194 are linked. During wrapping,
changes in the tension force exerted by packaging material 142 on sensing
element 194 may be caused by changes in instantaneous demand for packaging
material 142 at load 138. For example, an increase in the instantaneous demand
produces an increase in the tension force. A decrease in the instantaneous
demand produces a corresponding decrease in the tension force. Thus, sensing
element 194, by responding to changes in the tension force during wrapping,
also
responds to changes in the instantaneous demand. As the instantaneous demand
increases (producing an increase in the tension force), sensing element 194
may
be pulled toward its retracted position (e.g., toward the uppermost position
shown in
dashed lines in FIG. 5), thus increasing the supply rate of packaging material
142.
As the instantaneous demand decreases (producing a decrease in the tension
force), sensing element 194 may be pulled toward its extended position (e.g.,
toward the lowermost position shown in dashed lines in FIG. 5), thus
decreasing
the supply rate of packaging material 142. This is described in more detail
below.
[070] If, on the one hand, the tension force exceeds the force exerted by
force exerting mechanism 181, sensing element 194 will be pulled in the
direction
of the tension force (i.e., toward its retracted position). Through linkages
197 and
transmission lever 206, movement of sensing element 194 toward its retracted
position will decrease the input/output ratio of hydrostatic transmission 200,
thus
increasing the speed of upstream and downstream dispensing rollers 162, 164
proportionally, resulting in an increase in the supply rate of packaging
material 142.
As sensing element 194 is pulled toward its retracted position, the difference
between the tension force and the force exerted by force exerting mechanism
181
may begin to decrease. Reasons for the decrease may include the following:
movement of sensing element 194 toward its retracted position and/or the
increase

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in the supply rate may alleviate some of the tension in packaging material
142;
movement of sensing element 194 toward its retracted position may stretch
spring
device 183, thus increasing the force spring device 183 is capable of
exerting;
and/or continued relative rotation between roll carriage 144 and load 138 may
bring
packaging material dispenser 140 to a point of the wrapping cycle where there
is a
decrease in instantaneous demand for packaging material 142 at load 138 (as
will
be described below). As the difference between the tension force and the force
exerted by spring device 183 begins to decrease, movement of sensing element
194 toward its retracted position will slow down. If a point is reached where
the
force exerted by spring device 183 once again substantially equals the tension
force, sensing element 194 will stop moving toward the retracted position. The
new
position of sensing element 194 will correspond to a greater supply rate of
packaging material 142 than the position of sensing element 194 before the
increase in the tension force.
[071] If, on the other hand, the tension force falls below the force exerted
by
spring device 183, sensing element 194 will be pulled in the direction of the
force
exerted by spring device 183 (i.e., toward its extended position). Through
linkages
197 and transmission lever 206, movement of sensing element 194 toward its
extended position will increase the input/output ratio of hydrostatic
transmission
200, thus decreasing the speed of upstream and downstream dispensing rollers
162, 164 proportionally, resulting in a decrease in the supply rate of
packaging
material 142. As sensing element 194 is pulled toward its extended position,
the
difference between the tension force and the force exerted by spring device
183
may begin to decrease. Reasons for the decrease may include the following:
movement of sensing element 194 toward its extended position and/or the
decrease in the supply rate may increase the tension in packaging material
142;
spring device 183 may contract as sensing element 194 moves toward its
extended
position, and thus, the force spring device 183 is capable of exerting may
decrease;
and/or relative rotation between roll carriage 144 and load 138 may bring
packaging material dispenser 140 to a point of the wrapping cycle where there
is an
increase in the instantaneous demand for packaging material 142 at load 138
(as
will be described below). As the difference between the tension force and the
force
exerted by spring device 183 begins to decrease, movement of sensing element
194 toward its extended position will slow down. When a point is reached where

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the force exerted by spring device 183 once again substantially equals the
tension
force, sensing element 194 will stop. The new position of sensing element 194
will
correspond to a lesser supply rate of packaging material 142 than the position
of
sensing element 194 before the decrease in the tension force.
[072] Thus, it should be apparent that because the tension force and force
exerted by spring device 183 determine the position of sensing element 194,
then
the tension force and force exerted by spring device 183 also determine the
supply
rate of packaging material 142 during wrapping. By controlling the supply rate
of
packaging material 142 based at least in part on the tension force, and thus,
the
instantaneous demand for packaging material 142 at load 138, a selected payout
percentage may be maintained for at least a portion of a wrap cycle, even
though
characteristics of load 138 may change. That is, the selected payout
percentage
may be maintained for at least a portion of a wrap cycle even as demand for
packaging material at load 138 varies. It should be understood that while the
selected payout percentage may be maintained, it does not necessarily mean
that
a wrap force exerted on load 138 by packaging material 142 is maintained or
leveled, and in some instances, while the selected payout percentage remains
relatively constant, the wrap force may not, but rather, may vary to a higher
degree
than the selected payout percentage during wrapping.
[073] For example, when load 138 of FIGS. 5 and 6 is being wrapped, the
instantaneous demand for packaging material 142 at load 138 may change
numerous times during wrapping. When the instantaneous demand increases,
such as when packaging material dispenser 140 moves from wrapping top portion
145 to middle portion 143, or middle portion 143 to bottom portion 141, or
when
packaging material dispenser 140 wraps a corner of load 138 after having
wrapped
a flat surface of load 138, the increase in the instantaneous demand will
cause an
increase in the tension force exerted on sensing element 194 by packaging
material 142. The increase in the tension force will pull sensing element 194
toward its retracted position. Movement of sensing element 194 produces an
immediate response from hydrostatic transmission 200 in the form of increased
fluid flow from its input to its output, thus increasing the supply rate of
packaging
material 142, and increasing the amount of dispensed packaging material 142.
The
additional amount of packaging material 142 dispensed may compensate for the
increase in instantaneous demand, keeping the payout percentage substantially
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constant and/or in line with the selected payout percentage. By keeping the
payout
percentage substantially constant and/or in line with the selected payout
percentage, it is contemplated that the wrap force and/or containment force
may
remain substantially constant and/or in a selected range. The immediate
response
of hydrostatic transmission 200 may help to ensure that spikes in
instantaneous
demand for packaging material 142 do not cause breaks in packaging material
142,
by addressing increases in demand immediately.
[074] Whether the payout percentage remains substantially constant and/or
in line with the selected payout percentage may be determined in any number of
ways. For example, it is contemplated that a counter (not shown) may be
coupled
to at, least one roller, such as, for example, downstream dispensing roller
164
and/or an idle roller engaging dispensed packaging material 142. The counter
may
be configured to count the number of revolutions undergone by the at least one
roller during at least a portion of a wrap cycle. That count may be divided by
the
number of revolutions undergone by packaging material dispenser 140 during the
portion of the wrap cycle to determine the number of counts per revolution.
Since
the circumference of the at least one roller can be easily measured, the
dispensed
film per revolution of packaging material dispenser 140 can be calculated
based on
the number of counts, and that dispensed film per revolution can be compared
to
the measured girth of load 138 to determine the payout percentage. The
determined payout percentage may be compared to the selected payout
percentage. The process may be repeated during another portion of the wrap
cycle, to determine if and how much the payout percentage has changed between
portions of the wrap cycle.
[075] When the instantaneous demand decreases during wrapping, such as
when packaging material dispenser 140 moves from wrapping bottom portion 141
to middle portion 143, or middle portion 143 to top portion 145, or when
packaging
material dispenser 140 wraps a flat surface of load 138 after having wrapped a
corner of load 138, the decrease in the instantaneous demand will cause a
decrease in the tension force exerted on sensing element 194 by packaging
material 142. The decrease in the tension force will allow sensing element 194
to
be pulled toward its extended position by spring device 138. Movement of
sensing
element 194 produces an immediate response from hydrostatic transmission 200
in
the form of decreased fluid flow from its input to its output, thus decreasing
the

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supply rate of packaging material 142, and decreasing the amount of packaging
material 142 dispensed. The decreased amount of dispensed packaging material
142 may compensate for the decrease in instantaneous demand, once again
keeping the payout percentage substantially constant and/or in line with the
selected payout percentage.
[076] If the sensed decrease in the instantaneous demand is caused, for
example, by a partial break in packaging material 142, the response of
hydrostatic
transmission 200 may be proportional to the sensed decrease in the
instantaneous
demand. That is, hydrostatic transmission 200 will not immediately discontinue
dispensing of packaging material 142 upon sensing a decrease in instantaneous
demand, allowing the partially broken length of packaging material 142 to
reach
load 138, after which unbroken packaging material 142 can once again be
dispensed onto load 138. As such, downtime associated with full packaging
material breaks can be reduced or avoided. If, on the other hand, packaging
material dispensing was immediately and fully discontinued upon sensing of a
decrease in instantaneous demand, relative rotation between packaging material
dispenser 140 and load 138 would put additional stress on packaging material
142,
which could cause the partial break to become a full break.
[077] It is also contemplated that if, after load 138 is wrapped, the
subsequent load to be wrapped has a size and/or shape that is different from
the
size or shape of load 138, the payout percentage may remain at substantially
the
same level, and/or in line with the selected payout percentage, during
wrapping of
the subsequent load. For example, if the subsequent load is larger than load
138,
there will be a greater instantaneous demand for packaging material 142 at the
subsequent load. The increase in instantaneous demand, through its effect on
the
position of sensing element 194, will result in an increase in the supply rate
of
packaging material 142. Thus, the payout percentage may remain substantially
unchanged, and/or in line with the selected payout percentage, as the amount
of
packaging material 142 dispensed rises to meet the increase in the
instantaneous
demand. If, on the other hand, the subsequent load is smaller than load 138,
there
will be a smaller instantaneous demand for packaging material 142 at the
subsequent load. The decrease in instantaneous demand, through its effect on
sensing element 194, will result in a decrease in the supply rate of packaging
material 142. Thus, once again, the payout percentage may remain substantially

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unchanged, and/or in line with the selected payout percentage, as the amount
of
packaging material 142 dispensed falls to meet the decrease in the
instantaneous
demand. It should be understood that under any of the above-described
circumstances, a change in instantaneous demand for packaging material 142 at
load 138, or any other load to be wrapped, regardless of size, shape, or
orientation,
may result in a proportional change in the supply rate and amount of film
dispensed, such that the payout percentage may nevertheless remain
substantially
constant and/or in line with the selected payout percentage.
[078] Force exerting mechanism 181 may include an adjustment assembly
187, as shown in FIG. 7, for selectively and variably setting a force gradient
acting
on sensing element 194, and thus, setting the selected payout percentage
which,
as described above, may be maintained for at least a portion of a wrap cycle.
The
force gradient may be set by adjusting the initial force that spring device
183 is
capable of exerting on sensing element 194. Once the selected payout
percentage
has been set, it may be maintained for at least a portion of a wrapping cycle,
or
even during multiple wrapping cycles. Adjustment assembly 187 may be used to
adjust the initial force by tightening or loosening spring device 183,
changing the
effective length of spring device 183, preloading or unloading spring device
183,
and/or by any other suitable manner known to those skilled in the art. For
example,
it is contemplated that adjustment assembly 187 may shift frame portion toward
and
away from sensing element 194. Additionally or alternatively, adjustment
assembly
187 may be used to twist and/or untwist spring device 183 to adjust the
initial force.
Spring device 183 may include different types of springs, including, for
example,
tension springs, torsion springs, elastic bands, and/or any other suitable
types of
force exerting mechanisms. Spring device 183 may also include gas springs or
hydraulic devices with a piston and cylinder, with the force of such devices
being
variably adjustable by adjusting fluid pressure in the devices. It is
contemplated
that the force gradient may cover a small range of force values. That is,
spring
device 183 may be configured such that spring device 183 acts like a long
spring
such that there is a small amount of change in the force exerted by spring
device
183 over the range of movement spring device 183 may undergo during a wrapping
cycle. Put another way, spring device 183 may be configured to have a low
spring
rate.

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[079] By increasing the initial force, a greater tension force will be
required
to overcome the initial force to pull sensing element 194 toward its retracted
position. Moreover, once the tension force overcomes the initial force to
start
moving sensing element 194 toward its retracted position, even more tension
force
will be required to pull sensing element 194 further, since force exerting
mechanism
181 may become harder to stretch once it has already undergone some
stretching.
Thus, the supply rate of packaging material 142 will be less that it was
before
increasing the initial force. The decreased supply rate will produce a
decrease in
the amount of film dispensed, providing a decreased payout percentage. On the
other hand, by decreasing the initial force, a lesser tension force will be
required to
overcome the initial force to pull sensing element 194 toward its retracted
position.
Once the tension force overcomes the initial force to start moving sensing
element
194 toward its retracted position, additional tension force will be required
to pull
sensing element 194 further. However, that additional tension force will be
less
than the tension force required to achieve a similar change in position of
sensing
element 194 when the initial force is greater. Thus, the supply rate of
packaging
material 142 will be greater than it was before decreasing the initial force.
The
increased supply rate will produce an increase in the amount of film
dispensed,
providing an increased payout percentage. However, once the selected payout
percentage has been set, it may be maintained during at least a portion of the
wrap
cycle, even as characteristics of load 138 change, since movement of sensing
element 194 may adjust the supply rate to compensate for such changes.
[080] An alternative arrangement is shown in FIGS. 10 and 11. Features
shown in FIGS. 10 and 11 that are similar to features shown in FIGS. 1-3 and 7
have been assigned similar reference numerals, but with those reference
numerals
followed by the letter "a." A hydrostatic transmission 200a, similar to
hydrostatic
transmission 200, is shown with a transmission lever 206a (transmission lever
206a
is shown in multiple positions in FIGS. 10 and 11). An input/output ratio
setting of
hydrostatic transmission 200a may be selectively and variably adjusted by
transmission lever 206a. Rotation of transmission lever 206a in a first
direction
may decrease the input/output ratio. Continued rotation of transmission lever
206a
in the first direction may bring transmission lever 206a into a first
position, where
substantially all of the input at a rotatable input shaft 202a of hydrostatic
transmission 200a may be transmitted or translated to a rotatable output shaft
(not

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shown) of hydrostatic transmission 200a. Rotation of transmission lever 206a
in a
second direction may increase the input/output ratio. Continued rotation of
transmission lever 206a in the second direction may bring transmission lever
to a
second position, where transmission or translation of the input at rotatable
input
shaft 202a to the rotatable output shaft is prevented, putting hydrostatic
drive 200a
in a neutral state where rotatable input shaft 202a may rotate freely and
independently of the rotatable output shaft, and the rotatable output shaft
may stop
rotating. Since hydrostatic transmission 200a, like hydrostatic transmission
200,
operates based on fluid flow rather than based on fluid pressure, the lag time
associated with operating based on fluid pressure may be avoided.
[081] Transmission lever 206a may be coupled to a sensing element 194a
by linkages 197a. Sensing element 194a may include a sensing roller 195a
mounted for rotation on a shaft 212a. Shaft 212a may be cantilevered, and
pivotally mounted, such that one end may be capable of swinging back and forth
between an extended position (generally away from hydrostatic transmission
200a)
and a retracted position (generally toward hydrostatic transmission 200a).
Alternatively, sensing element 194a may include a bar, one or more wheels,
and/or
any other suitable devices for engaging packaging material.
[082] The swinging movement of sensing element 194a may rotate
transmission lever 206a through linkages 197a. As sensing element 194a swings
toward its extended position, transmission lever 206a may rotate in the second
direction, increasing the input/output ratio of hydrostatic transmission 200a.
As
sensing element 194a swings toward its retracted position, transmission lever
206a
may rotate in the first direction, increasing the input/output ratio of
hydrostatic
transmission 200a.
[083] A force exerting mechanism 181 a may affect the angular orientation
of transmission lever 206a and sensing element 194a, and thus, also may affect
the amount of film dispensed during the at least a portion of the revolution.
Force
exerting mechanism 181 a may include a spring device 183a. Spring device 183a
may include a compression spring having a first end 226 that engages a stop
220
on an arm 222 slidably received in a housing 224, and a second end 228 that
engages housing 224, as shown in FIG. 11. Alternatively, a gas spring, a
hydraulic
piston and cylinder, and/or any other suitable force exerting device may be
used. A
first end 184a of force exerting mechanism 181 a may be selectively fastened
to
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transmission lever 206a at any point along an arc slot 208. A second end 186a
of
force exerting mechanism 181a may be coupled to a frame portion 185a. Spring
device 183a may exert a force causing arm 222 to extend away from housing 224.
The force may be exerted by first end 184a on arc slot 208, forcing
transmission
lever 206a in the second direction. During normal operation, however, tension
in
the packaging material may exert a force on sensing element 194a drawing
sensing element 194a toward its retracted position, thus forcing transmission
lever
206a in the first direction. Accordingly, the force exerted by spring device
183a and
the tension force exerted by the packaging material may oppose one another.
[084] The instantaneous demand and the tension force exerted by the
packaging material on sensing element 194a are linked. During wrapping,
changes
in the tension force exerted by the packaging material on sensing element 194a
may be caused by changes in instantaneous demand for the packaging material at
the load. For example, an increase in the instantaneous demand produces an
increase in the tension force. A decrease in the instantaneous demand produces
a
corresponding decrease in the tension force. Thus, sensing element 194a, by
responding to changes in the tension force during wrapping, also responds to
changes in the instantaneous demand. As the instantaneous demand increases
(producing an increase in the tension force), sensing element 194a may be
pulled
toward its retracted position (e.g., toward the left in FIG. 10), causing
transmission
lever 206a to rotate in the first direction. As transmission lever 206a
rotates in the
first direction, arc slot 208 may move first end 184a of force exerting
mechanism
181a toward the fixed second end 186a, thus compressing spring device 183a
while increasing the supply rate of packaging material. As the instantaneous
demand decreases (producing a decrease in the tension force), spring device
183a
may decompress, causing first end 184a of force exerting mechanism 181 a to
move arc slot 208 (and transmission lever 206a) in the second direction, thus
decreasing the supply rate of packaging material while moving sensing element
194a toward its extended position (e.g., toward the right in FIG. 10). This is
described in more detail below.
[085] If, on the one hand, the tension force exerted on sensing element
194a by the packaging material exceeds the force exerted on sensing element
194a by spring device 183a, sensing element 194a will be pulled in the
direction of
the tension force (i.e., toward its retracted position). Through linkages 197a
and
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transmission lever 206a, movement of sensing element 194a toward its retracted
position will decrease the input/output ratio of hydrostatic transmission
200a,
resulting in an increase in the supply rate of packaging material. As sensing
element 194a is pulled toward its retracted position, the difference between
the
tension force and the force exerted by spring device 183a may begin to
decrease.
Reasons for the decrease may include the following: movement of sensing
element 194a toward its retracted position and/or the increase in the supply
rate
may alleviate some of the tension in the packaging material; movement of
sensing
element 194a toward its retracted position may compress spring device 183a,
thus
increasing the force spring device 183a is capable of exerting; and/or
instantaneous demand may decrease as a different portion of the load is
wrapped.
As the difference between the tension force and the force exerted by spring
device
183a begins to decrease, movement of sensing element 194a toward its retracted
position will slow down. If a point is reached where the force exerted by
spring
device 183a once again substantially equals the tension force, sensing element
194a will stop moving toward the retracted position. The new position of
sensing
element 194a will correspond to a new position of transmission lever 206a and
a
greater supply rate of packaging material than before the increase in the
tension
force.
[086] If, on the other hand, the tension force falls below the force exerted
by
spring device 183a, spring device 183a may decompress, causing transmission
lever 206a to rotate in the second direction, thus increasing the input/output
ratio of
hydrostatic transmission 200a, resulting in a decrease in the supply rate of
packaging material. Through first end 184a, transmission lever 206a and
linkages
197a, the decompression of spring device 183a may move of sensing element
194a toward its extended position. As sensing element 194a is moved toward its
extended position, the difference between the tension force and the force
exerted
by spring device 183a may begin to decrease. Reasons for the decrease may
include the following: movement of sensing element 194a toward its extended
position and/or the decrease in the supply rate may increase the tension in
the
packaging material; decompression of spring device 183a may cause the force
spring device 183a is capable of exerting to decrease; and/or instantaneous
demand may increase as a different portion of the load is wrapped. As the
difference between the tension force and the force exerted by spring device
183a
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begins to decrease, movement of sensing element 194a toward its extended
position will slow down. When a point is reached where the force exerted by
spring
device 183a once again substantially equals the tension force, decompression
of
spring device 183 a will stop, as will movement sensing element 194a. The new
position of transmission lever 206a and sensing element 194a will correspond
to a
lesser supply rate of packaging material than the position of transmission
lever
206a and sensing element 194a before the decrease in the tension force.
[087] Thus, it should be apparent that because the tension force and force
exerted by spring device 183a determine the position of transmission lever
206a
and sensing element 194a, then the tension force and force exerted by spring
device 183a also determine the supply rate of packaging material during
wrapping.
By controlling the supply rate of packaging material based at least in part on
the
tension force, and thus, the instantaneous demand for packaging material at
the
load, a selected payout percentage may be maintained for at least a portion of
a
wrap cycle, even though characteristics of the load may change. For example,
when the instantaneous demand increases, the supply rate of packaging material
will increase as described in the preceding sections, thus increasing the
amount of
dispensed packaging material. The additional amount of packaging material
dispensed may compensate for the increase in instantaneous demand, keeping the
payout percentage substantially constant and/or in line with the selected
payout
percentage. When the instantaneous demand decreases during wrapping, the
decrease, the supply rate of packaging material and amount of packaging
material
dispensed will decrease, thus decreasing the amount of dispensed packaging
material to compensate for the decrease in instantaneous demand, once again
keeping the payout percentage substantially constant and/or in line with the
selected payout percentage. The response of hydrostatic transmission 200a to
increases and decreases in instantaneous demand, like the response of
hydrostatic
transmission 200, may help to avoid creating full breaks in the packaging
material
during wrapping.
[088] Force exerting mechanism 181 a is adjustable for selectively and
variably setting the force gradient exerted on transmission lever 206a by
spring
device 183a. Force exerting mechanism 181a may be adjusted by loosening first
end 184a of force exerting mechanism 181a from transmission lever 206a, and
moving first end 184a to a new position along arc slot 208. By moving first
end
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184a toward a lower end of arc slot 208, arm 222 is moved away from housing
224,
allowing spring device 183a to decompress. By moving first end 184a toward an
upper end of arc slot 208, arm 222 is moved toward housing 224, compressing
spring device 183a. The force gradient exerted by spring device 183a may be
greater the more spring device 183a has been pre-loaded by being compressed by
arc slot 208. When first end 184a of force exerting mechanism 181 a has been
moved to a desired location along arc slot 208, first end 184a may be fastened
to
arc slot 208 by any suitable fastener, and/or by frictional force between
first end
184a and arc slot 208. Markings 210 along arc slot 208 may correspond to
payout
percentages. That is, by fastening first end 184a of force exerting mechanism
181a
next to a particular marking, a user may be setting a selected payout
percentage.
As described above, the selected payout percentage may be maintained for at
least
a portion of a wrap cycle, and/or between wrap cycles. The selected payout
percentage may be decreased by loosening first end 184a and refastening first
end
184a at a higher point on arc slot 208, and may be increased by loosening
first end
184a and refastening first end 184a at a lower point on arc slot 208. It is
contemplated that spring device 183a may have a low spring rate, like spring
device 183.
[089] It is also contemplated that second end 228 of force exerting
mechanism 181a may be spaced from housing 224. By providing the space, the
initial movement of sensing element 194a toward its retracted position may not
be
countered or impeded by the force exerted by force exerting mechanism 181 a.
This allows sensing element 194a to rotate transmission lever 206a in the
first
direction, decreasing the input/output ratio of hydrostatic transmission 200a,
in a
shorter period of time than would be the case if the space was not provided.
This
may help to ensure that enough packaging material is provided at the start of
a
wrapping cycle to prevent ripping an initial end of the packaging material
away from
a clamping assembly (not shown) holding the initial end as wrapping begins. A
yoke assembly 230, shown in FIG. 10, which may be spring-biased to rotate in a
first direction, may engage a cam 232 that forms a part of linkages 197a, to
help
push sensing element 194a to its full extended position once force exerting
mechanism 181 a has reached full decompression/extension.
[090] According to another aspect of the present disclosure, wrapping
apparatus 100 may be provided with a belted packaging material clamping and
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cutting apparatus, as described in U.S. Patent Application Publication No.
2007/0204564, entitled "RING WRAPPING APPARATUS INCLUDING METERED
PRE-STRETCH FILM DELIVERY ASSEMBLY," filed February 23, 2007, the entire
disclosure of which is incorporated herein by reference in its entirety.
[091] According to another aspect of the present disclosure, wrapping
apparatus 100 may be provided with a film drive down and roping system as
disclosed in U.S. Patent Application Publication No. 2007/0209324, entitled
"METHOD AND APPARATUS FOR SECURING A LOAD TO A PALLET WITH A
ROPED FILM WEB," filed February 23, 2007," the entire disclosure of which is
incorporated herein by reference in its entirety.
[092] According to another aspect of the disclosure, a method of using
wrapping apparatus 100, shown in FIG. 1, will now be described. In operation,
load
138 may be manually placed in the wrapping area, or may be conveyed into the
wrapping area by a conveyor (not shown). The selected payout percentage may
be set using adjustment assembly 187. A leading end of packaging material 142
may be threaded through upstream and downstream dispensing rollers 162, 164,
and around any idle rollers. Then, the leading end of packaging material 142
may
be wrapped around sensing element 194 before being attached to load 138 using
a
film clamp, by tucking the leading end of packaging material 142 into load
138, or
by tying the leading end to load 138 or a portion of a pallet supporting load
138.
[093] First motor 132 may operate to rotate first drive belt 130, and thus,
rotatable ring 122 and roll carriage 144, around load 138. As rotatable ring
122
rotates, a tension force may be created in the length of packaging material
142
extending between load 138 and sensing element 194. That tensile force may
tend
to pull sensing element 194 toward its retracted position against the force
exerted
on sensing element 194 by spring device 183 (see FIG. 7). Sensing element 194
will occupy a position where the tension force and the force exerted by spring
device 183 are substantially equal. As roll carriage 144 rotates relative to
support
structure 124, second drive belt 134 may be picked up by a pulley system 250
mounted to rotatable ring 122, and may move relative to rotatable input shaft
202 of
hydrostatic transmission 200, causing rotatable input shaft 202 to rotate.
Rotation
of input shaft 202 is immediately translated to output shaft 204 in the form
of fluid
flow in hydrostatic transmission 200, based on the position occupied by
sensing
element 194, and the rotation of the output shaft 204 in turn causes rotation
of
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upstream and downstream dispensing rollers 162, 164. As upstream and
downstream dispensing rollers 162, 164 rotate, they may elongate packaging
material 142 and dispense pre-stretched packaging material 142 during relative
rotation of roll carriage 144 relative to load 138. Roll carriage 144 may
rotate about
a vertical axis 158 as moveable frame 118 moves up and down non-rotating frame
110 to spirally wrap packaging material 142 about load 138.
[094] During the wrapping cycle, the instantaneous demand for packaging
material 142 at load 138 may change. If the instantaneous demand increases,
producing an increase in the tension force exerted on sensing element 194,
sensing element 194 may be pulled toward its retracted position, thus
increasing
the supply rate of packaging material 142 and the amount of packaging material
142 dispensed. If the instantaneous demand for packaging material 142 at load
138 decreases, producing a decrease in the tension force, sensing element 194
may be pulled toward its extended position, thus decreasing the supply rate of
packaging material 142 and the amount of packaging material 142 dispensed. In
either case, the selected payout percentage may be substantially maintained
even
as the instantaneous demand changes.
[095] The instantaneous demand may both increase and decrease multiple
times or not at all during a single wrap cycle. In response to each change, if
any,
the tension force acting on sensing element 194 may change. If the tension
force
increases, spring device 183 may stretch, and if the tension force decreases,
spring
device 183 may compress, and the position of sensing element 194 may shift
accordingly, until a new equilibrium point between the tension force and the
force
exerted by spring device 183 is reached. The repositioning of sensing element
194
may correspond to a change in the supply rate of packaging material 142 to
load
138 that compensates for the change in the instantaneous demand, thus
maintaining the selected payout percentage.
[096] For the embodiment shown in FIGS. 10 and 11, the method may be
similar to the above-described method, and may utilize similar components.
However, in the embodiment of FIGS. 10 and 11, the selected payout percentage
may be set by positioning first end 184a of force exerting mechanism 181 a
along
arc slot 208 next to the marking 210 corresponding to the selected payout
percentage.

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[097] Other embodiments of the disclosure will be apparent to those skilled
in the art from consideration of the specification and practice of the
disclosure
disclosed herein. It is intended that the specification and examples be
considered
as exemplary only, with a true scope and spirit of the disclosure being
indicated by
the following claims.

-38-

A single figure which represents the drawing illustrating the invention.

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Admin Status

Title Date
Forecasted Issue Date Unavailable
(86) PCT Filing Date 2011-01-21
(87) PCT Publication Date 2011-07-28
(85) National Entry 2012-07-20
Dead Application 2017-01-23

Abandonment History

Abandonment Date Reason Reinstatement Date
2016-01-21 FAILURE TO REQUEST EXAMINATION
2016-01-21 FAILURE TO PAY APPLICATION MAINTENANCE FEE

Payment History

Fee Type Anniversary Year Due Date Amount Paid Paid Date
Filing $400.00 2012-07-20
Registration of Documents $100.00 2012-10-26
Maintenance Fee - Application - New Act 2 2013-01-21 $100.00 2012-12-20
Maintenance Fee - Application - New Act 3 2014-01-21 $100.00 2013-12-19
Maintenance Fee - Application - New Act 4 2015-01-21 $100.00 2014-12-19
Current owners on record shown in alphabetical order.
Current Owners on Record
MOORE, PHILIP R.
JOHNSON, RICHARD L.
NORRIS, JOSEPH D.
LANTECH.COM, LLC
Past owners on record shown in alphabetical order.
Past Owners on Record
None
Past Owners that do not appear in the "Owners on Record" listing will appear in other documentation within the application.

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Abstract 2012-07-20 1 81
Claims 2012-07-20 11 443
Drawings 2012-07-20 11 201
Description 2012-07-20 38 2,347
Representative Drawing 2012-09-11 1 21
Cover Page 2012-10-09 2 70
PCT 2012-07-20 13 503
Assignment 2012-07-20 5 142
Correspondence 2012-07-20 2 113
Assignment 2012-10-26 3 167