Note: Descriptions are shown in the official language in which they were submitted.
CA 02734317 2011-03-17
TRAY DENESTER WITH AIR NOZZLE SEPARATORS
CROSS-REFERENCE TO RELATED APPLICATION
[0001] The present application is based on and claims priority to U.S.
Provisional Patent
Application Serial No. 61/315,155 filed on March 18, 2010.
BACKGROUND
[0002] The present disclosure generally relates to a tray denester. More
specifically, the
present disclosure relates to a tray denester having air nozzle separators to
remove one tray from
a stack of trays.
[0003] During normal packaging operations, products to be packaged are often
placed in
trays and further processed downstream from the packaging machine. Typically,
product trays
are shipped and stored in nested stacks in which each of the trays are placed
in close contact with
each other to reduce shipping costs. During the packaging operation, each tray
must be
separated from the stack of trays prior to loading the tray with a product.
Many different types
of mechanical assemblies have been developed to separate individual trays from
a stack of trays
for packaging. It is desirable that a tray denester be able to quickly and
reliably separate trays
from a stack to increase the packaging throughput of a facility. Further, it
is desirable that the
tray denester can be easily reconfigured to handle trays of different sizes.
SUMMARY
[0004] The present disclosure relates to a tray denester capable of separating
nested trays
from a stack one at a time. The trays are placed in a magazine where gravity
presents them to the
escapement section of the machine. The escapement mechanism of each magazine
holds the
stack from coming in contact with the product carrier plate except when
desired. The product
carrier plate is driven in a reciprocal manner towards and away from the stack
positioned in the
magazine.
100051 As the product carrier plate approaches the stack of trays, an air
nozzle assembly
is energized in a downward direction across the surface of the carrier plate.
The focused air blast
creates a low-pressure zone across the product carrier plate surface, which
aids in drawing the
first tray away from the stack. As the product carrier plate reaches the
stack, the stack is
-1-
CA 02734317 2011-03-17
released, causing the stack to come forward and contact the product carrier
plate. At the moment
the first tray contacts the product carrier plate, the energized air nozzle
causes the first tray to be
locked in place against the product carrier plate and the remaining stack to
be repelled, thereby
providing a path for the newly separated tray to be discharged.
[0006] After the separated tray is removed from the stack, the escapement
mechanisms
are activated and the product carrier plate moves away from the stack to
discharge the tray onto a
conveyor belt for downstream handling.
[0007] Various other features, objects and advantages of the invention will be
made
apparent from the following description taken together with the drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0008] The drawings illustrate the best mode presently contemplated of
carrying out the
disclosure. In the drawings:
[0009] Fig. I is a perspective view of the tray denester of the present
disclosure;
[0010] Fig. 2 is a top, rear view of the tray denester showing the position of
a pair of
product carrier plates in both the loading and unloading positions;
[0011] Fig. 3 is a top view of the tray denester;
[0012] Fig. 4 is a magnified view similar to Fig. 2;
[0013] Fig. 5 is a magnified view of one of the carrier plates including the
air nozzles and
escapements;
[0014] Fig. 6 is a magnified view showing the mounting of each of the air
nozzles used
to separate the product trays; and
[0015] Fig. 7 is a schematic illustration of the control unit of the tray
denester.
DETAILED DESCRIPTION
[0016] Fig. 1 illustrates a tray denester 10 that is used to dispense a series
of trays from
nested stacks 11 included in one of a series of product magazines 12. Each of
the product
magazines 12 includes a pair of sidewalls 14 that are spaced from each other
by the width of the
stack of trays I I such that the magazine positions the trays in a desired
orientation for separation.
Once each individual tray has been separated from the stack 11, the individual
tray is deposited
on a chute or a conveyor 16 such that the individual trays can be fed to
downstream equipment
-2-
CA 02734317 2011-03-17
for further processing. The tray denester 10 is constructed to allow a variety
of sizes of trays to
be dispensed, as well as a large range of thicknesses for each individual
tray. As illustrated in
Fig. 3, each product magazine 12 includes a sloped floor 18 that directs the
stack of trays through
the force of gravity toward a discharge end 20.
[0017] As illustrated in Fig. 3, the tray denester 10 includes a pair of
product carrier
plates 22a and 22b that are each movable relative to one of the stationary
product magazines 12.
In the embodiment shown in Fig. 3, the product carrier plate 22a is shown in a
retracted position
while the product carrier plate 22b is shown in the extended position. When
the carrier plate 22b
is in the extended position, the face surface of the carrier plate 22b is
positioned immediately
adjacent the discharge end 20 of the sloped floor 18 of the magazine 12. When
the product
carrier plate 22a is in the retracted position shown in Fig. 3, a discharge
opening 24 is created
between the carrier plate 22 and the discharge end 20. As illustrated in Fig.
3, the discharge
opening 24 allows trays to fall from the magazine 12 onto the conveyor belt
16. The conveyor
belt 16 operates to remove the denested tray from the tray denester 10 and
transport the tray for
further processing at the packaging facility.
[0018] Referring back to Fig. 1, the pair of carrier plates 22a and 22b are
each
independently movable as illustrated. The first carrier plate 22a is aligned
with the first two
product magazines while the second carrier plate 22b is aligned with the
second pair of product
magazines.
[0019] Each of the carrier plates 22a, 22b are independently movable to
separate a pair of
trays from the stack. In the embodiment shown in Fig. 1, carrier plate 22a is
in the retracted,
discharge position while carrier plate 22b is in the extended, loading
position.
[0020] As can be seen in Fig. 3, each of the carrier plates 22a, 22b are
mounted to a pair
of rods 26 that can be selectively retracted and extended to move the carrier
plates 22a, 22b
between the discharge and loading positions. As shown in Fig. 3, each of the
rods 26 pass
through a stationary support block 28 that guides the movement of the rods.
Each of the rods 26
is connected to a support bracket 29 that is movable as a result of the
operation of a drive motor
31. Drive motors 31 are each operatively coupled to a control unit 60 (Fig. 7)
for the tray
denester 10 such that the control unit 60 can synchronize the operation of the
drive motors 31
and thus the movement of the pair of carrier plates 22a, 22b. Although the use
of a pair of
spaced support rods 26 is shown in Fig. 3, it should be understood that
various other mechanisms
-3-
CA 02734317 2011-03-17
could be utilized for creating the reciprocal movement of the carrier plates
22a, 22b as shown
and described.
[0021] The drive motors 31 can move the carrier plates 22a and 22b between an
unlimited number of positions between the fully retracted and fully extended
positions. The
amount of movement of the carrier plates may depend upon the size of the tray
being dispensed.
As an example, the location of the retracted, discharge position can be
different for different size
trays. In this manner, the system can tailor the movement of the carrier
plates 22a and 22b to the
type of tray being dispensed.
[0022] Referring back to Fig. 5, each of the product magazines 12 includes at
least one
escapement mechanism 30 that is operable to selectively control the position
of the stack of
trays. Each escapement mechanism 30 includes an escapement plate 32 that
extends inward
from the sidewalls 14 to restrict the movement of the stack of trays. When
desired, a solenoid 34
of the escapement mechanism 30 can be activated to extend and retract to move
the plate 32 in
the direction shown by arrow 36.
[0023] As illustrated in Fig. 5, each of the product magazines 12 includes a
pair of
escapement mechanisms 30 mounted to each of the sidewalls 14 that define the
width of the
product magazine 12. Each escapement mechanism 30 includes its own escapement
plate 32.
When the escapement plate 32 is in the extended position shown in Fig. 5, the
inside edge 33 of
the escapement plate extends inwardly from the face surface 35 of the sidewall
14. Thus, the
escapement plates 32 reduce the effective width of the product magazine 12.
Preferably, the
product magazine 12 has a width that is approximately equal to the width of
the product trays
being dispensed. Thus, when the escapement plates 32 are in the extended
position shown in
Fig. 5, the escapement plates 32 prevent the stack of trays from contacting
the product carrier
plate 22b.
[0024] As described above, each of the escapement plates 32 are movably
mounted to a
solenoid 34 such that the escapement plates 32 are movable from the extended
position shown in
Fig. 5 to a retracted position (not shown). When the escapement plates 32 are
in the retracted
position, the inside edge 33 is generally aligned with the face surface 35.
When the escapement
plates 32 are retracted, the stack of trays slide down the sloped floor 18 and
into contact with the
product carrier plate 22b.
-4-
CA 02734317 2011-03-17
[0025] Each of the solenoids 34 of the escapement mechanism 30 are operatively
connected to the control unit 60 (Fig. 7) for the product denester such that
the operation of the
solenoids 34 can be coordinated with the movement of the product carrier
plates 22, as will be
described below.
[0026] As illustrated in Figs. 4 and 5, each of the carrier plates 22a and 22b
includes a
pair of nozzle openings 38 generally aligned with each of the product
magazines 12. Each of the
air nozzle openings 38 receives an air nozzle assembly 40. Each of the air
nozzle assemblies 40
includes an air nozzle 41 and an air hose connection 43 each contained on a
main body 45. The
air hose connection 43 receives a supply of pressurized air that flows into
the main body 45 and
out of the nozzle 41. The nozzle 41 is specifically designed to direct air in
a specific flow
pattern. In the embodiment shown in Fig. 5, the main body 45 is mounted to a
support bracket
47. The support bracket 47 is movable relative to the stationary product
carrier plate 22b. The
vertical position of the support bracket 47, and thus the air nozzle assembly
40, can be adjusted
by loosening a connector 42. The connector 42 is movable within an adjustment
slot 46
positioned directly adjacent to the nozzle openings 38. When the connector 42
is tightened, the
vertical position of the support bracket 47 is secured. When it is desirable
to adjust the vertical
height of the air nozzle assembly 40, the connector 42 is loosened and the air
nozzle assembly
moved to the desired vertical position. Once in the desired vertical position,
the connector 42 is
again tightened to secure the air nozzle assembly in the adjusted position.
[0027] As can be seen in Figs. 5 and 6, the air nozzle 41 is positioned such
that the air
nozzle creates a blast of air directed along an air flow axis 49. In the
embodiment illustrated, the
air flow axis 49 is selected to be approximately 45 relative to vertical.
Although 45 is shown
in the embodiments of Figs. 5 and 6, it should be understood that the angle of
the air flow axis 49
could be adjusted. The angle of the air flow axis can be adjusted by loosening
connector 51 and
adjusting the orientation of the support bracket 47 until the air flow axis 49
reaches the desired
orientation.
[0028] As can be seen in Fig. 4, each of the air nozzle assemblies 40 are
positioned to
direct the flow of air both downward and toward the respective product carrier
plate 22a, 22b.
Thus, when the air nozzle assembly 40 receives the flow of pressurized air,
air flow from the
nozzle 41 flows toward the respective product carrier plate 22a, 22b to create
an area of low
pressure along the product carrier plate.
-5-
CA 02734317 2011-03-17
[0029] The operation of the tray denester will now be described.
[0030] As can be understood in Fig. 5, each of the escapement mechanisms 30
holds
back the stack of trays in two different manners. The first is to actually
position the escapement
plate 32 in front of the stack of trays. The second is to provide sufficient
side pressure to
overcome the moments of force imposed on the trays by gravity. During
operation, the control
unit 60 sends a control signal to the escapement mechanisms 30 such that the
mechanisms are
opened at specific moments in order to release a stack of trays causing the
stack of trays to drop
and come into contact with the product carrier plate 22 when the product
carrier plate 22 is in the
loading position, as shown by product carrier plate 22b in Fig. 1.
[0031] At the moment right before the stack of trays comes into contact with
the product
carrier plate 22b, the control unit opens air valves 62 (Fig. 7), which allows
a supply of air to
flow to the air nozzle assembly 40. The control unit is programmed such that
as the product
carrier plate 22b moves toward the discharge end of the magazine 12, air is
supplied to the air
nozzle assembly. The supply of air is directed across the carrier plate 22b
and forms a low-
pressure zone due to the flow of air in this location. The low-pressure zone
draws the first tray
from the stack into contact with the carrier plate 22b. The continued stream
of air from the air
nozzle assembly 40 separates the first tray from the stack. In addition to
separating the first tray,
the flow of air repels the remaining stack away from the product carrier plate
22b.
[0032] As can be understood in Fig. 6, the focused air blast from the air
nozzle assembly
40 is produced at a specific angle (45 ) with respect to the product carrier
plate through non-
conical Venturies to produce an air blast with a modified fan pattern, longer
in one axis than the
other. This has the desired effect of holding the first tray in place while
causing a volume of air
to find its way through the minute opening between the first and second tray,
causing the second
tray and those above it to be lifted from the first.
[0033] The air nozzle assembly 40 shown in Fig. 6 helps to reduce air
consumption by
making better use of air proportioned to them. Furthermore, the focused air
blast from the air
nozzles has the added benefit of having a shorter rise time for the desired
effect as more air
reaches its intended target.
[0034] As illustrated in Fig. 6, the air nozzle assembly 40 is mounted
directly to the
support bracket 47 and is adjustable vertically by the series of the
connectors 42.
-6-
CA 02734317 2011-03-17
[00351 The product carrier plates are each driven up and down in a reciprocal
manner
with a controlled servomotor or a stepper motor in a "cam profile", which is a
non-linear profile.
The tray denester has a user definable engagement time of the tray to the
product carrier plate to
provide more flexibility to handle larger ranges of tray sizes.
[00361 The product carrier plate is guided with roller element bearings for
positions to
maintain a specific approach angle to hold the product in contact with the
carrier plate once the
tray has been engaged. The escapements and the air blasts are choreographed to
the angular
orientation of the crank arm that connects the drive system to the product
carrier plate.
[00371 Once each tray is locked to the product carrier plate 22 by the focused
air blast
from the air nozzle assembly 40, the carrier plate 22 is retracted. As the
product carrier plate 22
is retracted, there is a point where there is sufficient plate space to permit
the tray to exit. As
described above, this location will vary depending on the tray depth. The
location is defined in
the control unit for each type of tray dispensed. At the discharge location,
the air blast from the
air nozzle assemblies 40 are terminated and a focused blast from air nozzle
assembly 52 (Fig. 4)
positioned above the trays is created. As illustrated in Fig. 4, the air
nozzle assembly 52
positioned above the top edge 53 of each of the product carrier plates 22a,
22b, includes a
mounting bracket 55, an air nozzle 57, a body 59 and an air hose connector 61.
As illustrated in
Fig. 4, a separate air nozzle assembly 52 is provided for each of the product
magazines 12. Thus,
each of the air nozzle assemblies 52 can be activated to separate the product
tray from the
product carrier plate 22a or 22b to help direct the tray toward the conveyor
assembly 16. The air
blast from above is directing the tray onto the conveyor belt as described.
100381 As can be understood by the above description and the schematic
illustration of
Fig. 7, the control unit 60 of the tray denester controls the timing of the
operation of the various
operational components within the tray denester. The timing of the operation
of the various
components of the tray denester allows the tray denester to selectively
discharge one tray from
the stack of trays for further processing downstream. The timing of the
operation of the various
components within the tray denester varies depending upon the type of tray
being discharged.
As an illustrative example, when the trays being discharged are thin and
lightweight, the low-
pressure zone created along the product carrier plate can be reduced by
reducing the amount of
air flow through the air nozzle assemblies. Alternatively, when the trays are
heavy and thick, the
air flow through the air nozzle assemblies must be increased to increase the
low-pressure zone.
-7-
CA 02734317 2011-03-17
Further, the operation of the escapement mechanism 30 must be properly
coordinated depending
upon the thickness and size of the trays.
[0039] Typically, the control unit 60 is programmed through an input device 64
which
may be a touch screen, keyboard or other device that allows the operator to
input commands and
variables into the control unit 60. Once the desired operating parameters are
determined for a
particular type of tray, the operating parameters are stored within a memory
unit 66 of the
control unit 60 for later retrieval. Each time a new tray style is used with
the tray denester, the
control unit 60 stores the determined operating parameters and timing sequence
in the memory
unit 66. Thus, when the same or similar tray style is dispensed at a later
date, the user can
retrieve the operating parameters from the memory unit 66 through operation of
the input device
64. In this manner, the operator can select different tray styles from a menu
based upon past
operation of the tray denester.
[0040] During operation of the tray denester, if the tray denester is not
operating to
discharge individual trays at an acceptable failure rate, the operator can
adjust the operating
parameters of the system through the input device 64. As an illustrative
example, the use may
increase the air flow provided to the air nozzle assemblies 40 by opening the
air valve 62 earlier
in the movement of the product carrier plate. Alternatively, the escapement
mechanism may be
delayed to prevent the stack of trays from reaching the product discharge
plate until the product
carrier plate gets closer to the discharge end of the magazine.
[0041] In one embodiment of the disclosure, the input device 64 includes a
graphic user
interface (GUI) that allows the user to select from various different menu
selections in an
intuitive manner. Various different types of GUIs are being contemplated as
being within the
scope of the present disclosure.
[0042] In the embodiment shown in Fig. 7, the control unit 60 is a
microprocessor-based
control unit. However, it is contemplated that different types of control
units, such as a PLC or
microcontroller could be utilized while operating within the scope of the
present disclosure.
[0043] In the embodiment shown in Fig. 7, the control unit is operatively
connected to
various components of the tray denester. However, additional connections are
contemplated as
being within the scope of the present disclosure.
[0044] In the embodiments shown in Figs. 1 and 2, the tray denester is shown
having
four product magazines 12, each of which are controlled by one of two product
carrier plates
-8-
CA 02734317 2011-03-17
22a, 22b. The tray denester shown in Figs. I and 2 is a modular device that
can be modified
easily by adding additional magazines to the denester. As an illustrative
example, two additional
magazines could be added to the tray denester 10 by simply adding a pair of
magazines, an
additional product carrier plate and the associate equipment needed to move
the product carrier
plate. In such an embodiment, the additional two magazines would be connected
to the control
unit and the control unit programmed to operate three separate product carrier
plates and the
associated equipment.
-9-
