U.S. patent application number 14/514362 was filed with the patent office on 2015-04-16 for pallet load sensing system.
The applicant listed for this patent is Best Packaging, Inc.. Invention is credited to Stephen Francis Kudia.
Application Number | 20150101281 14/514362 |
Document ID | / |
Family ID | 52808469 |
Filed Date | 2015-04-16 |
United States Patent
Application |
20150101281 |
Kind Code |
A1 |
Kudia; Stephen Francis |
April 16, 2015 |
PALLET LOAD SENSING SYSTEM
Abstract
The present invention relates to a system for positioning
pallets to be wrapped with a pallet stretch wrap machine and to
adjust operation of the wrap machine according to measurements
obtained from sensors, identify the relative size of the pallet
load to be wrapped in stretch film, detect misalignment of the load
and thereby control activation of the wrap sequence and the speed
of the film applied.
Inventors: |
Kudia; Stephen Francis;
(Brookfield, IL) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Best Packaging, Inc. |
Broadview |
IL |
US |
|
|
Family ID: |
52808469 |
Appl. No.: |
14/514362 |
Filed: |
October 14, 2014 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61890404 |
Oct 14, 2013 |
|
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|
Current U.S.
Class: |
53/51 |
Current CPC
Class: |
B65B 2210/20 20130101;
B65B 57/12 20130101; B65B 57/18 20130101; B65B 2210/16 20130101;
B65B 11/025 20130101; B65B 2210/02 20130101 |
Class at
Publication: |
53/51 |
International
Class: |
B65B 57/12 20060101
B65B057/12; B65B 11/02 20060101 B65B011/02 |
Claims
1. A pallet load sensing and control system of a floor-loaded
stretch wrap apparatus having an arm that rotates around a pallet
to wrap the pallet in stretch wrap, the system comprising: a laser
sensor device for measuring at least an extent of a first face and
at least an extent of a second face of a floor-loaded pallet and
generating assigned values for said measurements; a controller for
electrical connection to the stretch wrap machine, said controller
configured for receiving said measurement values and comparing said
values to stored information regarding pallet tolerances; and a
signal generator coupled to the controller, the signal generator
being configured to provide a differential signal based on
comparison of the measurement values to the stored information.
2. The system of claim 1 wherein said measurement values are
compared to stored information of the acceptable tolerances for the
pallet being in correct position for initiating a wrap sequence of
the stretch wrap apparatus.
3. The system of claim 1 wherein said measurement values are
compared to stored information of pallet size and wherein the
signal generator provides a differential signal for adjusting the
speed of the shrink wrap apparatus.
4. The system of claim 3 wherein the controller is configured to
identify the pallet dimensions within a tolerance of a pallet size,
and wherein said signal generator is configured to provide
alternate signals to the wrap assembly depending on the pallet
size.
5. The system of claim 4 wherein said signal generator is
electrically connected to a frequency drive of a motor of the wrap
assembly, such that the motor is run slower for a smaller pallet
size and the motor is run faster for a larger pallet size.
6. The system of claim 5 wherein the signal generator initiates a
different signal depending upon the measurement values residing
within one of alternate pallet sizes.
7. The system of claim 3 wherein a drive motor of the wrap assembly
is driven by a current that has a lower frequency when a smaller
pallet is detected and said motor is driven by a current of higher
frequency when a larger pallet is detected.
8. The system of claim 7 wherein a drive motor of the wrap assembly
is driven by a 60 Hz frequency current when a particular pallet
size is identified and said motor is driven by a current less than
60 Hz when a smaller pallet size is identified.
9. The system of claim 7 wherein a drive motor of the wrap assembly
is driven by a 60 Hz frequency current when a measurement value is
about 52 inches and said motor is driven by lower frequency current
when the greatest measurement value is about 40 inches.
10. The system of claim 1 wherein said controller further
comprises: a first processor for calculating pallet position data
comprising the distance from the pallet on all sides to a
prestretch carriage to an arm of the wrapping assembly; an encoder
coupled to the arm, wherein said encoder transmits position data
comprising the position of the arm relative a reference position;
and a second processor for calculating the distance between the arm
and the pallet at points around the pallet using the arm position
data and the pallet position data.
11. A pallet load sensing and control system for use with a
floor-loaded stretch wrap apparatus having an arm with a prestretch
carriage configured to rotate around a pallet to wrap the pallet in
stretch wrap, the system comprising: a sensor for determining at
least a dimension of first face and a dimension of a second face of
a floor-loaded pallet and generating values of the measurements; a
controller coupled to the stretch wrap machine, the controller
receiving the dimension values and calculating pallet position data
relative a reference position; wherein said controller provides a
signal to the stretch wrap apparatus to activate a shrink wrap
sequence if the pallet is within a predetermined location in
relation to the reference position.
12. The system of claim 11 wherein said controller further
comprises: a first processor for calculating pallet position data
within a zone of a wrapping apparatus and an encoder coupled to the
arm, wherein said encoder transmits position data comprising the
position of the arm relative a reference position; and said
controller further comprising a second processor for calculating
the distance between the arm and the pallet at points around the
pallet using the arm position data and the pallet position
data.
13. A pallet load sensing and control system for use with a
floor-loaded stretch wrap apparatus having an arm with a prestretch
carriage configured to rotate around a pallet to wrap the pallet in
stretch wrap, the system comprising: at least a first sensor for
identifying a position of at least a side of a pallet load and a
second sensor for identifying a position of another portion of the
load; a controller coupled to the stretch wrap machine, the
controller electrically connected to receive signals from the first
and second sensors and having a computer processor for calculating
the position of at least a portion of the load and said controller
thereby generating a signal transmitted to the stretch wrap
apparatus to identify when a pallet is in position and misalignment
is not detected.
14. An apparatus for controlling an amount of pre-stretched packing
film applied about a load, comprising: at least one primary sensor
positioned about a packing station for a palletized load, said
sensor configured to emit a detection beam directed toward a load
wrapping station and configured to identify a border of the load
when positioned in said station and generate a primary sensor
signal; at least one secondary sensor positioned relative said
packing station, said secondary sensor configured to emit a
secondary detection beam at a predetermined position relative the
wrapping station, such that said secondary sensor is able to detect
the presence of the load at said predetermined position; and
thereby generates a secondary sensor signal; a processor
electronically connected to said primary and secondary sensors to
receive the primary signal of the load and to receive the secondary
signal, said processor configured to initiate a warning condition
in the event the load is misaligned within the wrapping
station.
15. The apparatus of claim 14, wherein the secondary sensor is
positioned to emit said sensor beam outside a border of said
wrapping station.
16. The apparatus of claim 15 wherein said secondary sensor
generates an electric signal identifying mis-alignment of the load,
and said signal being transmitted to the processor wherein the
processor is programmed to prevent the wrapping apparatus from
initiating a wrapping sequence.
17. The apparatus of claim 14 wherein the primary sensor is a laser
and said secondary sensor is an electric eye.
18. The apparatus of claim 17 wherein said primary sensor laser
measures a distance to the load and the processor operates to
compare said distance measurement with information regarding a
border of said wrapping station.
19. A pallet load sensing system for use with a floor-loaded
stretch wrap machine having an arm that rotates around a pallet to
wrap the pallet load with stretch wrap, the system comprising: a
first photo eye, said first photo eye positioned opposite one face
of a floor-loaded pallet load for generating a signal identifying
the presence of a pallet load; a second photo eye, said second
photo eye positioned adjacent a load station area and directing a
photo eye beam to detect obstruction of a photo eye beam by load; a
processor for receiving said signal of the first photo eye and a
signal from the second photo eye, said processor having a computer
processor configured for determining whether a load is in proper
position for operation of the stretch wrap apparatus; a signal
generator in communication with the processor for providing a
signal to initiate operation of the stretch wrapping assembly to
commence the wrapping sequence of the load.
20. The system of claim 19 further comprising two photo eyes
deployed about the load station, each positioned at opposed ends of
the station to detect obstruction of respective photo eye beams by
the load.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application claims priority to U.S. Provisional Patent
Application No. 61/890,404, filed on Oct. 14, 2013, the content of
which is fully incorporated herein by reference.
BACKGROUND
[0002] Pallets of various goods are stretch-wrapped for secure
transportation. Automated stretch-wrap machines are commonly used
for stretch wrapping a palletized load, which include conveyor-type
systems in which pallets are loaded and transported on a conveyer,
and manual stretch wrap systems in which pallets are floor-loaded
using a forklift or pallet jack, positioned at a wrapping machine
by an operator, and then again transported by an operator after the
wrapping operation. Floor-loaded stretch wrapping systems may
comprise a single arm for wrapping a single pallet, or may be
multi-headed for wrapping multiple pallets simultaneously. In the
case of multi-head assemblies, i.e., wrapping assemblies with
multiple wrapping stations, when a pallet is incorrectly positioned
in any one station of the apparatus, each incorrectly loaded
station will fault out and not operate while the wrapping sequence
at the correctly loaded stations will operate through the sequence
of covering their respective pallet load with stretch wrap. In some
cases, the wrapping head of each working station will finish
wrapping before the incorrectly positioned pallets can be adjusted,
which results in additional operator efforts in the unloading of
wrapped pallets and loading of new pallets. Further, often the
pallets are positioned at the wrapping assembly such that, when one
of the loads is not in proper orientation and the wrap sequence is
thereby not activated or is shut down at that station, it is not
possible for an operator to reach the problem due to the other
pallet loads being in the way.
[0003] Additionally, due to manual positioning of the pallet in a
floor-loaded system, the distance from the film prestretch device
of the stretch wrap machine to the pallet may differ from one load
to another. This results in a condition in which a skewed or
misaligned load in a station is positioned such that there are
varying distances between the load and the prestretch device as the
film prestretch device rotates around the pallet. The variable
distance between the load and the prestretch device requires
adjustment for proper wrapping of the load, such that the film
speed of the prestretch device must accelerate and decelerate the
film to make up for distance changes. This causes stress on the
film at the prestretch device and potential breakage of the film,
resulting in failure of the wrapping operation and down-time due to
the need for an operator to correct the problem. Therefore, proper
positing and alignment of a load at a wrapping station is very
important to ensure continued function of a stretch wrap apparatus,
and which is especially important for proper operation of an
apparatus having multiple wrapping stations.
[0004] In addition, it is significant for proper function of a
floor-loaded pallet wrapping system to ensure that the proper
tension and amount of the stretch wrap film is applied to the load.
In systems utilizing a prestretch head, such adjustments may be
made by altering the speed of the film being applied to the load.
Such adjustment of the film speed at the prestretch head may be
manually performed, requiring an operator to identify the need for
an adjustment of the speed to accommodate a smaller or larger load
prior to a wrapping operation. Further, challenges exist with
making such speed adjustments, which may require mechanically
altering the film drive mechanism, such as altering a gear ratio at
the motor of a prestretch head device. Therefore, there is a need
for a stretch wrapping apparatus that will automatically identify
alterations of a load at a wrapping station to enable adjustment of
the film speed at the prestretch head. The present invention
addresses these challenges.
OBJECT OF THE INVENTION
[0005] It is an object of the invention to provide a system for
positioning pallets to be wrapped with a pallet stretch wrap
machine and controlling the speed of the wrapping sequence for
optimal results. Specifically, the present invention is designed
for use with a floor-loaded single- or multi-headed stretch wrap
machine, and comprises one or more sensors which obtain
measurements of a pallet load placed within the loading station
area, and signals whether the pallet is correctly positioned for
wrapping by the stretch wrap machine. The system ensures that the
pallet is in proper position for wrapping, and, if a pallet is in
an incorrect position as determined by the laser sensor, immediate
action can be taken by the operator of the pallet transport machine
to correct the fault prior to initiating wrapping. It is also an
object of the present invention to obtain the measurements of the
distance between the stretch wrap machine prestretch device and the
exterior surface of the placed pallet, and communicating these
measurements to the prestretch device to predetermine how much film
will be needed to wrap a pallet and when the film will be
needed.
[0006] The system of the present invention offers several benefits,
including: (i) the ability to use thinner films (which are more
cost effective than thicker films), (ii) less film breaks as the
acceleration and deceleration demands placed on the films is
significantly less, (iii) a smoother unwind of film ultimately
provides a higher force to load throughout the pallet, as film that
is accelerated and decelerated stretches film too far not allowing
the film to recover and hold the pallet, and (iv) the ability to be
provided with a film cost per pallet as a pallet is put into the
stretch wrap machine.
[0007] Other objects, advantages, features, properties and
relationships of the invention will be obtained from the following
detailed description and accompanying drawings which set forth
illustrative embodiments that are indicative of the various ways in
which the principles of the invention may be employed.
BRIEF DESCRIPTION OF THE DRAWINGS
[0008] FIG. 1 is a view of the system of the present invention with
one laser, shown as used in connection with a single-post,
three-station floor-loaded stretch wrap apparatus;
[0009] FIG. 2 is a top plan view of the system of the present
invention with two laser devices, shown as used in connection with
a four-post floor-loaded stretch wrap apparatus;
[0010] FIG. 3 is a top plan view of the system of the present
invention in which two sensors are directed at a single load and
positioned at adjacent corners of the pallet load;
[0011] FIG. 4 is a top plan view of an alternate embodiment of the
present invention, including bumper tracks on opposed sides of the
pallet load and electric eyes positioned to detect the presence or
absence of the load at each side of the proper position of the load
in a wrapping station of a stretch wrap apparatus;
[0012] FIG. 5 is a side view of an embodiment of the present
invention as shown in FIG. 4, including bumper tracks on opposed
sides of the pallet load and a sensor positioned above the load and
a sensor positioned adjacent the load to identify whether the load
is in proper position of a stretch wrap apparatus;
DETAILED DESCRIPTION
[0013] The description that follows describes, illustrates and
exemplifies one or more embodiments of the present invention in
accordance with its principles. This description is not provided to
limit the invention to the embodiments described herein, but rather
to explain and teach the principles of the invention in order to
enable one of ordinary skill in the art to understand these
principles and, with that understanding, be able to apply them to
practice not only the embodiments described herein, but also other
embodiments that may come to mind in accordance with these
principles. The scope of the present invention is intended to cover
all such embodiments that may fall within the scope of the appended
claims, either literally or under the doctrine of equivalents.
[0014] In a preferred embodiment, the present invention includes a
pallet load sensing and control system 2 of a floor-loaded stretch
wrap apparatus 4 having an arm that rotates around a pallet load 8
to wrap the load in stretch wrap (not shown). The system 2
comprises at least one sensor device 10 that emits a sensor beam 12
for measuring at least an extent of a first face 14 and a sensor
beam that measures at least an extent of a second face 16 of a
pallet load 8. The system 2 then generates assigned values for each
the measurements derived from the sensor 10. Preferably, the
assigned measurement values will include a measurement of the width
of the load as it exists at a particular height of the load, such
as the width of the load when measured at approximately 30 inches
above the floor level of the pallet bottom 18. The system 2
includes at least one controller 20 for electrical connection to
the stretch wrap machine 22, wherein the controller 20 is
configured to receive the measurement values and compare those
values to stored information relating to pallet 8 dimensions and/or
tolerances. For example, the stored information may include ranges
of values for pallet sizes, such as typical ranges for pallet loads
on a 36 inch wide pallet or a 40 inch wide pallet or a 52 inch wide
pallet. The system 2 further includes a signal generator (not
shown) associated with and coupled to the controller 20, the signal
generator being configured to provide a differential signal to the
stretch wrap machine 22 based on comparison of the measurement
values to the stored information.
[0015] Thus, the present invention provides a sensing and control
system for a floor-mounted stretch wrap assembly 4, whereby sensor
beams 12 are utilized to obtain the measurements of a pallet load
8, such that a differential signal is transmitted to the stretch
wrap device 22. The differential signal may be used to activate or
prohibit the wrapping sequence, such as a signal identifying a load
out of proper position at a stretch wrap station 24, as the sensors
10 are utilized to detect alignment or misalignment of the pallet
load 8. Alternatively, the differential signal may differ according
to identification of differing dimensions of a pallet load or class
of pallet load size, information which may be used to adjust the
speed of the film being applied by the stretch wrap device 22 such
as by adjustment of the speed of the motor (not shown) at a
prestretch carriage device 26 that rotates in a carriage area 27
about a load 8 being wrapped. In this embodiment, the sensors 10
are used to identify the width of the pallet load, that information
is transmitted to a processor for comparison to pre-programmed
information regarding pallet size and used to determine and control
the appropriate speed of the motor of the prestretch carriage 26.
Thus, the differential signal transmitted to the wrap assembly 22
of this embodiment is a signal that initiates control of the motor
speed and thereby adjusts the speed of the stretch wrap film.
[0016] The present invention serves as a detection and control
system for a floor-loaded, non-automated apparatus 4, in which
pallets 8 are loaded by forklifts or pallet jacks into position at
stations 24 for wrapping, rather than being placed on a conveyor
belt of an automated system. Correct manual positioning of a pallet
is challenging, and this challenge is amplified in multi-station
system such as that disclosed in co-pending U.S. patent application
Ser. No. 12/178,473, filed Jul. 23, 2008, the disclosure of which
is incorporated herein by reference. As shown in FIG. 1 of the
present application, which depicts a stretch wrap apparatus 4 that
includes three stations 24 for wrapping pallet loads 8 in position
at a respective stretch wrap station 24, each of the pallet loads 8
are manually placed in position, at an appropriate distance apart
from one another.
[0017] This system may be used with a variety of floor-loaded
wrapping machines, including the single-post structure 28 shown in
FIG. 1 and the four-post structure 30 shown in FIG. 2 (which shows
a stretch wrapping station from above). A four-post system
comprises arms mounted to four posts rather than a single post,
providing increased stability to allow, for example, faster
spinning of wrapping heads. As seen in FIG. 2, when the system is
coupled to a four-post structure, the sensors 10 may be mounted
directly onto a post 30 of the apparatus (as opposed to a separate
stand where the post is absent, such as the single-post structure
of FIG. 1). In either case, the sensors 10 are preferably mounted
at approximately 30 inches above the floor, a height determined to
be at least half the load height. In the embodiment where a single
sensor 10a is used, the sensor 10a scans two faces 14, 16 of the
positioned pallet 8 to obtain measurements of the width and depth
dimensions of the pallet 8. At least one other sensor 10b is
mounted at another location about the load wrapping station 24, as
shown in FIG. 2, preferably positioned at an opposite corner of the
station 24, or as shown in FIG. 3, positioned at an adjacent corner
of the wrapping station 24.
[0018] In a preferred embodiment, such as shown in FIG. 1, the
sensors 10 are comprised of laser sensors, each positioned to emit
a beam on at least a side of the load 8. As shown in FIG. 1, the
stretch wrap apparatus 4 includes three stations 24 for wrapping
pallet loads 8, each station 24 shown with a pallet load 8 that is
at or near the proper position for the stretch wrap to be applied
by a device 26 of the stretch wrap machine 22. At each station 24
of the apparatus 4, at least one laser sensor 10, and preferably at
least two laser sensors 10a, 10b, obtains measurements of the
pallet load 8 which is then used to initiate a signal for the
apparatus, such as a signal identifying whether the pallet is
correctly positioned with respect to the wrap machine 22. In an
alternate embodiment, the laser sensor 10 may be used to identify
outer dimensions of the pallet for adjustment of the stretch wrap
film speed and/or adjustment of the rotational area 27 of the
carriage 26 of the wrapping apparatus relative the load 8, which is
adjusted by the control of the assembly transmitting an appropriate
signal identifying a dimension of the load or by comparing the load
dimensions to stored data (residing in a data memory device of the
controller 20) relating to categories of pallet load sizes. An
example of a laser sensor 10 for use with the present invention is
the TiM3xx Laser Scanner manufactured by SICK AG. As used with a
stretch wrap machine 22 such as that of FIG. 1, at least one laser
sensor 10 is mounted adjacent the a wrapping station 24 of the
apparatus, preferably on a non-moveable stand or post 32 and facing
a corner of a pallet position. The laser device 10 is positioned at
a location generally along a diagonal line 34 through a pallet load
8 when placed in the station 24, such as shown in FIGS. 2 and 3. As
such, the laser 10 is in position to scan at least an extent of two
sides 14, 16 of the load 8, as shown in the Figures. Thus, a single
laser 10 is capable of obtaining measurements that may be used to
determine the size of the load, i.e., at least measuring the load
width along two sides to determine the size of the rectangular or
square load.
[0019] In one embodiment, each laser sensor 10 assigns a value to
the measurement of the load 8. That value is transmitted to a
controller 20 and used to determine the position of the load 8 and
identify whether the load 8 is skewed in the station 24 or is in an
acceptable orientation for commencing the wrapping sequence. Such
calculations or determinations are preferably made at a processor
of the controller 20 that receives electrical signal from each
sensor 10, such as signals transmitted from each laser 10 to the
processor 24 via conduit 36 of the apparatus 4. In the embodiment
shown in FIG. 1, each sensor 10 is electrically connected to a main
controller 20 via a sub-controller or junction station 38. In this
manner, it is contemplated that signals from each sensor 10 may
pass directly to the master controller 20, or signals from each
sensor device 10 may be transmitted to a respective sub-controller
38 for manipulation or processing of the signal information prior
to data being transmitted to the master controller 20. At least one
computer processor (not shown) is provided at the master controller
20 and/or the sub-controller 38 for processing the information
received relative the sensor signal and comparing that information
with pre-loaded information in memory associated with the
processor, including data regarding the acceptable range of the
pallet load position and/or the range of pallet load size.
[0020] Multiple sensors 10 are used to obtain additional and
comparative measurements of the pallet load 8. As shown in FIGS.
1-3 at least two sensors 10a, 10b are preferably positioned about
each stretch wrap station 24 of the apparatus 4. In the embodiment
shown in FIGS. 1 and 2, sensors 10a, 10b are positioned at opposed
sides of each station 24, generally at opposite corners of the
pallet load position, each generally positioned along a diagonal
line 34. In this embodiment, each sensor 10a, 10b is configured and
positioned to cast a layer beam 12 to identify the width of two
sides 14, 16 of the load 8, thus measuring each side of the load
residing at one or more specified load height. In the embodiment
shown and described, each sensor 10a, 10b is a laser capable of
obtaining such measurements of at least an extent of the load
width. Data from the measured values is then compared to
pre-programmed values to determine the width dimensions of the
pallet load, such as determining whether the pallet load is one of
three alternate classes of pallet sizes, such as pallet loads of 40
inches by 48 inches, 36 inches by 36 inches, or 52 inches by 52
inches. The processor 20 may then assign an appropriate stretch
film speed according to the respective general sizes of pallet
loads using pre-programmed information of the processor data
memory.
[0021] In operation, after an operator loads the one or more pallet
loads 8 in the stations 24 of the apparatus 4, the laser sensors 10
of each station 24 detecting a pallet load is configured to measure
at least two faces 14, 16 of the pallet load 8. Information from
such measurements is then processed at the controller 20 computer
processor. The controller 20 subsequently provides feedback
regarding the machine's tolerances for the rotation of the carriage
26 of the machine around the pallet for wrapping the pallet load.
If the measurements obtained are within of the allowed tolerances
of position and/or dimensions of the load, an immediate signal to
the forklift operator, via visual or audio indicators, may be
provided. For example, different colored lights (green, yellow,
red), flashing lights of steady or varying frequency (not shown),
or audio tones, may be used to signal pallet position information
to the operator. If the pallet 8 is incorrectly placed at a station
24, the operator can then make necessary adjustments to the
position of the one or more pallets to ensure proper positioning,
before the machine 22 begins the wrapping sequence at any station
24. Further, regardless of whether such signal information is
provided to the operator, the controller is preferably configured
to utilize the measurement values to send a signal to each
respective stretch wrap machine 22 of the apparatus 4, indicating
that the stretch wrap operation should be initiated.
[0022] Further, the controller 20 is preferably configured to
utilize the load measurement values to send adjustable signal to
the prestretch carriage 26 of each respective stretch wrap device
22 of the apparatus 4, to adjust the speed of the motor of the
carriage 26 and thereby control the speed of the film in the
wrapping sequence. In this aspect of the invention, the prestretch
carriage 26 of each stretch wrap machine 22 rotates about the
pallet load on a fixed path. In common devices, the speed of the
carriage 26 may be increased or decreased at certain locations
about the load 8 to accommodate for the distance between the load 8
and the apparatus 26 applying the film. The apparatus 4 of the
present invention optionally utilizes the load size determination
(the width measurements) to vary the speed of the film applied
rather than requiring adjusted speed of the arm of the prestretch
carriage device 26. Specifically, the controller 20 is configured
to utilize the load measurement values to send adjustable signal to
the motor of the prestretch carriage 26, thereby adjusting the
speed of the film being applied to the load 8.
[0023] Therefore, in addition to determining pallet placement
tolerances and communicating a signal regarding such information
for operation of the assembly, the pallet measurements obtained by
the sensors can be used by the controller 20 to essentially
determine the distance between the prestretch carriage device 26
and the pallet load 8, and to communicate such information to the
prestretch device 26 to adjust the amount of film needed and
applied to wrap a pallet 8. The prestretch carriage 26 includes a
motor that supplies the film and stretches the film as it is
applied to the pallet load. Different sized pallets demand that
different amount of films be delivered to the pallet to ensure a
tight wrap, because too much film on a small pallet will result in
loose film. When pallets are manually loaded, the distance between
the film carriage and pallet may change from pallet to pallet even
when the pallet is the same size. However, the system of the
present invention compensates for the respective size of the load
8, which defines the distance between the pallet load and the
prestretch carriage, such that the prestretch carriage is adapted
to deliver film at the appropriate speed to ensure a tight wrap of
the pallet load. The ability to predetermine how much film is
needed and when film is needed allows for a smother unwind of film
(less forceful acceleration and deceleration of film), which offers
a number of benefits.
[0024] As shown in FIGS. 1-3, the laser sensors 10 measure the
width of the sides 14, 16 of the pallet load 8, provides such data
to the stretch wrap machine controller 20, which then processes the
information with an algorithm to determine distance from the pallet
to prestretch carriage on all sides. In combination with the laser
sensor 10, an encoder (not shown) is coupled to the arm that holds
the prestretch carriage 26. The encoder transmits data to the
controller 20, specifying the exact position of the carriage 26.
With the carriage position data from the encoder and the pallet
position data from the sensors 10, the distance between the arm and
the pallet at all points around the pallet is determined. The
system 2 thus allows predetermination of the amount of film needed
to wrap a pallet load 8 prior to commencing the wrapping sequence.
Thus, when the film is needed, it is delivered in a more consistent
manner. This provides the advantages of (i) controlling film
tension to the pallet more accurately; (ii) determining an exact
amount film needed to wrap a load to ensure that more film than
needed is not used; and (iii) the ability to use thinner films
rather than thicker, more expensive films.
[0025] An alternative embodiment for determining pallet placement
tolerances and communicating a signal regarding the pallet
placement at a station 24 is also contemplated. In this embodiment,
two or more photo eyes 40, 42, 44 are used to determine the
positioning of a floor-loaded pallet 8. As shown in FIGS. 4 and 5,
an embodiment comprising at least two photo eyes, the first photo
eye 40 is positioned above the floor-loaded pallet 8 for
identifying the presence of the load, and a second photo eye 42 is
positioned adjacent the pallet load to identify whether the load is
in a suitable position for the wrapping sequence to commence. This
is preferably achieved by the first photo eye 40 being directed
within the area for the pallet within the station 24, and the
second photo eye 42 having a generally horizontal detection beam
passing adjacent and outside the acceptable location for the pallet
load 8. The second photo eye 42 is positioned such that a beam will
detect obstruction by the pallet, thereby identifying the pallet to
be outside the proper area of the station 24. A processor 20
receives input from the first photo eye 40 and is capable of
receiving input from the second photo eye 42, and processes the
information to determine whether the detected pallet 8 is in
suitable position. A signal is then generated by the processor 20
to commence the wrapping operation when the proper conditions are
met. Further, an audio and/or visual signal may be activated by the
processor 20 to provide the pallet forklift operator information of
the status of the pallet, i.e., whether the pallet is within the
acceptable tolerances to initiate the wrapping sequence.
[0026] In the embodiment shown in FIG. 4, a third photo eye 44 is
provided at the opposite end of the pallet station 24 relative the
second photo eye 42. The third photo eye 44 is positioned such that
a detection beam 45 will identify whether the opposite side of the
pallet load 8 is in position by determining whether the load
obstructs the beam 45. Further, in an embodiment it is contemplated
that the position of horizontal photo eye beams 45 of the second
and/or third photo eye 42, 44 may be adjusted to accommodate for
differing sizes of pallets, or may include multiple beams 45 at
each photo eye device 42, 44 as is shown in FIG. 4. The embodiment
utilizing one or more photo eyes does not necessarily detect pallet
skew or misalignment, and thereby guiderails or bumper rails 46 may
be deployed to assure that the pallet 8 is acceptably aligned in
the station 24. This embodiment of the system could be used with a
single-headed machine or with machines having varying numbers of
wrapping heads.
[0027] While specific embodiments of the invention have been
described in detail, it will be appreciated by those skilled in the
art that various modifications and alternatives to those details
could be developed in light of the overall teachings of the
disclosure. Accordingly, the particular arrangements disclosed are
meant to be illustrative only and not limiting as to the scope of
the invention which is to be given the full breadth of the appended
claims and any equivalent thereof.
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