Note: Descriptions are shown in the official language in which they were submitted.
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ROBOTI C PALLETI ZER
sackaround of the Invention
This invention relates generally to palletizers
and more particularly, to robotic palletizers operable
to automatically lift and place cartons onto a pallet in
a predetermined pattern or arrangement.
As one of the final steps in many manufacturing
operations it is necessary to load containers of
manufactured products onto pallets for shipment from the
manufacturing facility. In high speed, high volume,
manufacturing operations, such loading or "palletizing"
can be very labor-intensive if performed manually; and a
variety of machines or "palletizers" have been
developed for automatically per~orming this function.
Because substantial savings in labor costs can be
realized when automatic palletizing is utilized in high
speed, high volume operations, such palletizing can be
economically ~ustified despite a relatively high
initial cost and demanding service requirements for each
such palletizing machine. In low speed, low volume
operations, however, the potential labor cost savings
are far lower, and an automatic palletizer should have a
simpler construction and have a relatively lower initial
cost if it is to provide a significant economic
advantage over manual palletizing.
Prior palletizers have utilized electronic and
mechanical encoders, in combination with a
computer-based control system, to keep track of the
actual position of a carton as it is transported and
placed onto a pallet. Although effective, the use of
such encoders significantly increases the cost of such
prior palletizers, requires service skills of experts
and renders such palletizers economically unsuitable for
use in low speed, low volume palletizing applications.
In Vi8W of the foregoing, it is a general ob~ect of
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the present invention to provide a new and improved
robotic palletizer.
It is a more specific object of the present
invention to provide a new and improved robotic
palletizer which can be economically manufactured and
serviced and which can be advantageouslY utilized in low
speed, low volume palletizing operations.
Summary of the Invention
The invention provides a robotic palletizer
operable to automatically place and arrange a plurality
of objects in a predetermine~ pattern on a pallet. The
robotic palletizer includes a hand assembly adapted to
releasably grasp one or more of the objects and further
includes a support assembly operable to support the hand
assembly for independent movement in a substantially
vertical direction and also in a substantially
horizontal direction. Proximity detector, movable with
the hand assembly, sense the presence and absence of
accumulated objects on the pallet to control the
position and elevation of the hand assembly for placing
objects on the pallet.
The invention also provides a telescoping
horizontal arm for use in the robotic palletizer. The
telescoping horizontal arm comprises a rigid, hollow,
elongate outer member having an associated longitudinal
axis. An elongate intermediate member, having a
longitudinal axis aligned substantially parallel with
the longitudinal axis of the outer member, is
telescopically receiYed in the outer member and includes
an elongate lower surface. An idler wheel is mounted
within the intermediate member for rotation in a
substantially vertical plane and extends partly below
the lower surface of the intermediate memberO An
elongate inner member, telescopically disposed within
the intermediate member and having a longitudinal axis
aligned substantially parallel with the longitudinal
axis of the intermediate member, engages the idler wheel.
Means are provided for displacing the inner member
relative to the intermediate member in a direction
substantially parallel to the longitudinal axis of each
so as to rotate the idler wheel and thereby cause the
idler wheel to displace the intermediate member, and the
inner member, relative to the outer member.
According to an aspect of the invention, a robotic
palletizer for automatically placing and arranging a
plurality of objects in a predetermined pattern of rows
and columns on a pallet, comprising a vertical support
column, a vertically displaceable support assembly
slidably mounted to the support column, a horizontally
displaceable arm assembly slidably mounted to the support
assembly, a hand assembly mounted to an outboard end of
the arm assembly and having outboard and inboard plates
for grasping the objects therebetween, and a detector
means for sensing the presence and absence of objects on
the pallet, characterized in that the detector means is
carried by the hand assembly and comprises a first
proximity detector means for controlling the vertical
position of the hand assembly and a second proximity
detector means for controlling the horizontal position.
Brief Description of the Drawings
The features of the present invention are set forth
with particularity in the appended claims. The invention,
together with the objects and advantages thereof, can
best be understood by reference to the following
description taken in conjunction with the accompanying
drawings wherein like reference numerals identify like
elements, and;
Figure 1 is an isometric view of a robotic
palletizer embodying various features of the invention;
and
Figure 2 is a cross~sectional view of the
robotic palletizer illustrated in Fig. 1 taken along line
2-2 thereof.
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Description of the Pre~erred Embodiment
A robotic palletizer 10 embodying one form of
the invention is illustrated in the Figures. The
robotic palletizer 10 functions to receive a plurality
of regularly shaped objects, such as shipping packages,
cases or cartons 12, and automatically place the cartons
12 in a predetermined pattern on a shipping pallet 14.
As illustrated, the robotic palletizer 10 includes a
vertical support column, or "Z'i axis 16, and an
extendable horizontal arm or "Y" axis assembly 18 mounted
for bi-directional vertical movement along the "Z" axis
16. A hand or grasping assembly 20, adapted to
releasably grasp at least one and preferably a plurality
of the cartons 12, is mounted to an extendable end 22 of
the "Y" axis assembly 18. The hand assembly 20 is thus
supported by the "Z" axis 16 and by the "Y" axis assembly
18 for independent movement in both the vertical and
horizontal directions. Preferably, the "Y" axis assembly
18 comprises a telescoping horizontal arm.
The "Y" axis assembly 18 is supported for vertical
movement along the "Z" axis 16 by means of a carriage 24
movable along the vertical column 16. A chain 25 (Fig.
2) is attached at one end to the carriage 24 and at the
other end to a counterweight 26 within the vertical
column 16. The chain 25 is also reeved over a sprocket
28 located at the top of the column 16. When the sprocket
28 is turned by means of an electric motor 30, the chain
is driven in one direction or the other to cause the
carriage 24 to move up or down along the vertical column
16. An adjustable limit switch 32 is provided for
sensing when the carriage 24 has reached a predetermined
lower limit relative to the vertical column 16.
The "Y" axis assembly 18 includes one end 34 which
remains horizontally stationary relative to the vertical
column 16. The extendable end 22 is driven horizontally
inwardly or outwardly relative to the vertical column 16
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4a
under the power of an electric drive motor 36. The hand
assembly 20 includes an outer hand plate or palm 38 and a
parallel inner hand plate or palm 40 which can be driven
toward or away from the outer hand plate 36. The hand
assembly 20 can thereby grasp a row of the cartons 12 for
placement onto the pallet 14, or can release the
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cartons 12 onto the pallet 14. An adjustable limit
switch 42 (Fig. 2) is provided for sensing when the "Y"
axis assembly 18 has been extended to a prede~ermined
limit.
The telescoping horizontal arm 18 includes an
elongate outer member or box frame 19, which is of
substantially rectangular cross-section and has
associated therewith a longitudinal axis. An elongate
intermediate member, or carriage 23, is telescopically
received in the box frame and is aligned substantially
parallel with the longitudinal axis of the box frame 19.
The telescoping horizontal arm 18 further includes
an elongate inner member or hand tube 21, which is
telescopically disposed within the intermediate member
or carriage 23. The longitudinal axis of the hand tube
21 is aligned substantially parallel with the
longitudinal axes of the carriage 23 and the box frame
19 .
An idler wheel or roller 29 (Fig. 2) is mounted
within the carriage 23 for rotation in a substantially
vertical plane around an axle 31 oriented substantially
perpendicularly to the planes formed by side walls 27 o
the carriage 23. The idler wheel 29 is positioned so
that a portion of the wheel extends partly below the
lower surface of the carriage 23 and into contact with
the bottom interior surface 17 of the box frame 19. Tha
idler wheel 29 also extends into contact with an
undersurface 15 of the hand tube 21 at a point
substantially diametrically opposed to the point of
contact between the idler wheel 29 and the box frame 19.
The axle 31 rides in a pair of opposed vertical slots
formed in the side walls 27 of the carriage 23 so as to
permit limitad vertical movement of the idler wheel 29
relative to the carriage 23.
The undersurface 15 of the inner member or hand
tube 21 also rests on a support roller 33 mounted to the
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forward end of the carriage 23. In this manner, the
inner member 21 is supported b~ the idler wheel 29 and
the support roller 33 for axial extension or retraction
relative to the carriage 23.
The inner member 21 is extended or retracted
relative to the carriage 23 by means of a motor-driven
friction or drive ~heel 35 mounted to the upper end of
the carriage 23 and positioned so as to engage and bear
against the upper surface 13 of the inner member 21.
The drive wheel 35, together with its associated drive
motor 36, is mounted between a pair of brackets 37 which
extend along opposite sides of the carriage 23 and which
are vertically movable relative thereto. Each of the
brackets 37, in turn, is affixed to the carriage 23 by
means of a bolt extending through the bracket 37 and
into a nut-like tab extending outwardly from each side
of the carriage 23. By tightening or loosening the
bolts, the vertical position of the motorized drive
wheel 35 can be changed relative to the carriage 23.
This adjustment allows th user to make the carriage 23
and the hand tube 21 substantially parallel with the box
frame 19.
The intermediate member of the carriage 23 is
supported for lateral translation relative to the outer
member or box frame 19. Part of this support is by
means of a roller assembly 39 mounted at the rear of the
carriage 23 and engaging the upper interior wall 41 of
the box frame 19. The remainder of the carriage 23 is
ultimately supported by the idler wheel 29. The
supporting force to the front of the carriage 23 is
applied upward to the idler wheel 29 at the point where
it contacts the lower interior wall of the box frame 19.
The vertical position of the idler wheel 29 relative to
the carriage 23 is not fixed. ~ather, the idler wheel
29 is permitted to float, and the upward contact force
from the lower wall of box frame 19 is transmitted
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directly through the idler wheel 29 to the underside of
the inner member 21. This force is then transmitted
through the inner member 21 to the carriage 23 via the
drive wh~el 35, the bolts and the nut-like tabs.
Accordingly, the traction between the drive wheel 35 and
the inner member 21 can be reliably maintained even as
the drive wheel 35 and the idler wheel 29 wear during
operation.
In operation, rotation of the friction or drive
wheel 35 results in lateral translation of the inner
member or hand tube 21 relative to the carriage 23.
Movement of the inner member 21 in one direction
relative to the carriage 23 causes the idler wheel 29 to
rotate. Such rotation of the idler wheel 29 causes the
carriage 23 to move in the same direction relative to
the outer member or box frame 19. During extension or
retraction of the horizontal arm 18, the motorized drive
wheel 35 is fixed relative to the carriage 23.
Therefore, the inner member 21 moves relative to the
carriage 23 while the carriage 23 moves in the same
direction relative to the box frame 19. The inner
member 21 moves at about twice the speed of the carriage
23 due to the locations of contact with the idler wheel
29 - one contacting the other at the idler wheel 29 at
the axle and the other at the outer ~iameter thereof.
Means are provided for ensuring that the speed of
the inner member 21 relative to the carriage 23 is
substantially equal to the speed of the carriage 23
relative to the box frame 19. To this end, a pair of
sprockets 44 are mounted on opposite sides of the idler
wheel 29 so as to be co-rotatable therewith. A first
chain ~6, having one end attached to the rear of the
inner member 21, is reeved over one of the sprockets 44.
The opposite end of the first chain 46 is attached to
the interior of the box frame 19 at a point located
rearwardly of the idler wheel 29. A second chain 48 is
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connected at one end to the forward end of the inner
member 21 and is reeved over the other one sprocket 44.
The second chain 48 is attached, at its opposite end, to
the interior o~ the box frame l9 at a point located
forwardly of the idler wheel 29. During extension or
retraction of the horizontal arm 18, the chains 46 and
48 function to ensure that the lateral translation of
the inner member 21 relative to the box frame lg is
substantially twice the translation of the carriage 23
relative to the box frame 19.
The robotic palletizer l`urther includes an
infeed conveyor 44l a pallet dispenser 46 in which empty
pallets 14 are stored, and a pallet conveyor 48 which
conveys the empty pallets 14 from the dispenser 46 to a
loading position shown in Fig. 1. A user control panel
50, containing suitable control circuitry, is provided
for controlling operation of the palletizer 10.
The infeed conveyor 44 functions to meter,
orient and accumulate the cartons 12 prior to loading
onto tha pallet 14. The infeed conveyor 44 receives the
cartons 12 from an upstream conveyor (not shown), such
as a gravity or low back pressure conveyor. The infeed
conveyor 44 includes a low-speed section 52 and a
high-speed section 54 downstream of the low speed
section 52. Because of the speed differential between
these high-speed and low-speed sections, the cartons 12,
which have been initially conveyed onto the low speed
section 52, automatically become spaced apart, as they
encounter the high-speed section 54. Upon reaching the
end of the high-speed section 54, the cartons 12 are
stopped and accumulated. A first photodetector 56,
responsive to the passage of each of the cartons 12,
counts the cartons 12 as each enters the high-speed
section 54 of the conveyor 44. This information is
provided to the control circu.itry. As the cartons 12
pass the photodetector 5~ (also responsive to the
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passage of each of the cartons 12) into the accumulation
area of the conveyor 44, this information is also
provided to the control circuitry for determining
completion of a row of the cartons 12 in the
accumulation area.
The infeed conveyor 44 is configured so that a
sufficient num~er of the cartons 12 are accumulated at
one time to form one row in each layer on ~he loaded
pallet 14. The cartons 12 can thus be accumulated in
side-by-side relationship as shown in Fig. 1. In the
alternativs, a carton turning mechanism 60, located
adjacent the inlet end of the high-speed section 54, can
be actuated by the control circuitry to place the
cartons 12 in end-to-end relationship as they are
accumulated.
The positions of the cartons 12 and the hand
assembly 20 relative to the pallet 14 are sensed by
proximity detector means. The proximity detector means
senses for sensing the presence and absence of the
accumulated cartons 12 on the pallet 14 to control the
position of the hand assembly 20 for placing the cartons
12 on the pallet 14. For example, one can use a pair of
proximity detectors 62 and 64 mounted on a support 66
which extends horizontally outwardly from the hand
assembly 20. In the illustrated embodiment, the first
and second proximity detectors 62 and 64 each preferably
comprise an infrared photodetector system including a
self-contained infrared source and infrared detector.
The horizontal support 66 is located such that when the
hand assembly 20 is in position ovsr the pallet 14,
the support 66 extends adjacent and along side the
cartons 12 in place on the pallet 14. The support 66
is also positioned to be roughly one inch above the
bottom surface of the cartons 12 being carried by the
hand assembly 20.
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The first proximity detector 62 ia located
substantially at the outermost end of the support 66 and
faces toward the sides of the cartons 12 in place on the
pallet 14. The second proximity detector 64 is
positioned slightly outboard of the outer hand member 38
and also faces toward ths sides of the cartons 12 in
place on the pallet 14.
During a pallet loading operation the first and
second proximity detectors 62 and 64 operate in
conjunction with control means, such as suita~le
microprocessor based control circuitry in the control
panel 50. These proximity detectors 62 and 64 function
to sense the position of the hand assembly 20 relative
to the cartons 12 already in place on the pallet 14. In
particular, the first proximity detector 62 operates to
generate a first control signal characteristic of the
vertical position of the hand assembly 20. Thus, the
first proximity detector 62 senses when the height of
the hand assembly 20 is sufficient to provide vertical
clearance between the cartons 12 already in place on the
pallet 14 and the cartons 12 in the ~rasp of the hand
assembly 20. Similarly, the second proximity detector
64 operates to generate a second control signal
characteristic of the horizontal position of the hand
assembly 20. Thus, the second proximity detector 64
senses when the horizontal extension o~ the horizontal
arm 18 is sufficient to place the outermost edge of the
grasped cartons 12 adjacent the innermost edge 68 of
the top row of the cartons 12 already in place.
Within the control panel 50, the control circuitry
operates to control the palletizer 10 in accordance
with: (a) various user-generated predetermined control
inputs, (b) by the inputs, or control signals, provided
by the above discussed photodetectors 56, 58 and the
proximity ~etectors Ç2, 64 and (c) by the various limit
switches 32, 42.
Preferably, the control system comprises a
programmed commercially available, microprocessor-based
circuit, such as the "SLC150" Processor manufactured by
Allen Bradley Company as part no. 1745-LP 153.
Programming of the control system involves entering
various predetermined operat:ional data, such as the
number of cartons 12 per row; the orientation of each
of the cartons 12 within the row, spacing (per user
requirements) between the adjacent cartons 12 within the
row and the total number of the cartons 12 for a fully
loaded form of the pallet 14 This predetermined
operational data and the con1:rol signal information is
manipulated by a computer software program (the source
code output of the program is set forth in the Software
Appendix). Control of the robotic palletizer 10 is thus
effectuated in accordance with the execution of the
computer program instructions which utilize the
predetermined operational data input by the user and the
control signal information as the variable parameters.
The cartons 12 are then conveyed onto the low-speed
section 52 of the infeed conveyor 44. When a sufficient
number of the cartons 12 have been accumulated to form
one row on the pallet 14, the hand assembly 20 closes to
grip the accumulated cartons 12.
With the reference to the partially loaded pallet
14 as shown in Fig. 1, when the pallet 14 is initially
empty, the first row of the cartons 12 is positioned on
the pallet 14 by raising the "Z" axis for a
predetermined time, then extending the "Y" axis assembly
18 until the limit switch 42 associated therewith is
activated. The "Z" axis is then lowered to the position
of a "home" limit switch 32, and the hand assembly
releases the cartons 12 onto the pallet 14. After the
first row of the cartons 12 is thus deposited on the
pallet 14, the hand assembly 20 is withdrawn to the
initial, or "home", position over the infeed conveyor
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44. That is, the "Z" axis raises in accordance with a
timer signal from the control circuitry, the "Y" axis
retracts until the "home" limit switch 42 is actuated,
and the "Z" axis lowers until the "home" limit switch 32
is actuated. When the next row of the cartons 12 has
been accumulated the "z" axis raises for a prsdetermined
time then the "Y" axis assembly 18 is extended until the
second photodetector 64 detects the inner edge of the
previously deposited first row of the cartons 12. The
"Z" axis is then again lowered until the "home" limit
switch 32 is actuated. The second row of the cartons 12
is then released and is deposited on the pallet 14 in
close proximity to the firs~ row. Operation in this
manner continues until the first layer of the cartons 12
on the pallet 14 is completed.
To form the second layer of the cartons 12 on the
pallet 14, the horizontal arm 18 is first raised along
the "Z" axis 16 until the first proximity detector 62
clears the top of the first layer. Once sufficient
vertical clearance over the previously deposited layer
is established, the first row of the second layer is
constructed by extending the "Y" axis assembly 18 until
the limit switch 42 associ`ated therewith is actuated,
which will then lower the "Z" axis a predetermined
distance. (This distance is readily adjustable by
adjusting a timer in the control circuitry.) After the
first row o~ the second layer is thus positioned and
deposited, subsequent rows are constructed by extending
the "Y" axis assembly 18 until the second proximity
detector 64 detects the inner ed~e of the cartons 12
already in place in the second layer. Operation
continues in this manner until the requisite layers ha~e
been formed on the pallet 14. Once the pallet 14 is
fully loaded, it is removed from the pallet conveyor
48; and a new pallet is brought into the loading
position.
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If it is desired to Eorm an interlocking loading
pattern on the pallet 14, the control circuitry
actuates the case turner 60 so as to turn the carton~ 12
in alternate rows prior to accumulation and thereby form
a desired interlocking loading pattern on th0 pallet 14.
The robotic palletizer 10 therefore includes a
number of significant commercial advantages. ~he
position of the cartons 12 in each row on the pallet 14
is determined either by the limit switch 42 or by
actuation of the first and second proximity detectors 62
and 64. It is therafore unnecessary to monitor the
actual position of the hand assembly 20 during each
loading cycle. This eliminates the need ~or costly and
complex encoding techniques (and associated hardware)
for continuously sensing the location of the hand
assembly 20. These features thus contribute to the
overall economy and serviceability of the robotic
palletizer 10. The structure of the robotic palletizer
10 also results in a rugged apparatus which can handle
relatively heavy cartons and allows long term
performance and straightforward servicing.
While a particular embodiment of the invention has
been shown and described, it will be obvious to those
skilled in the art that changes and modifications may be
made without departing from the invention in its
broader aspects, and, therefore, the aim in the appended
claims is to cover all such changes and modifications as
fall within the true spirit and scope of the invention.
