Note: Descriptions are shown in the official language in which they were submitted.
L3
~ack rouncl of the Invention
g -- .
(1) Field of the Invention
-
The present invention relates to devices for handling
articles in general and more particularly to automatic
devices for depalletizing/palletizing boxes and manipulating
them, for instance, for transferring them from one position
to another as on an assembly line.
(2) Prior Art
In order to reduce product cost, improve product
quality and increase product throughput, the current trend
in industry is to automate the assembly lines -that manufacture
the product. ~utomated assembly lines necessitate the use
of robotic systems for performing tasks that were formerly
done by humans~ A fully automated assembly line includes a
conveyor system with a plurality of workstations disposed
along the conveyor system. The conveyor system transports
the components that are used to manufacture the product
while the actual fabrication of the product is done at the
different workstations.
2 ~5~
Each workstation i9 fitted with a robotic system
designated to perform an assigned taskO Included in -the
assigned task is the depall tiziny of boxes. Usually the
hoxes carry the components that are used in the fabrication
of a particular product. Other tasks include opening the
boxes, removing -the components from the boxes, assembling
the component in a finished product, -testing the product,
packaging the product, and palletiziny the product for
shipment to -the ultimate user.
The typical robotlc system includes a robot and an
article handling system connected to the robot. The article
handling system is usually designed to handle and/or manipulate
the article while the robot is the mechanism that moves the
article handling system and its attached article to a
designated point. Article handling systems may be broadly
classified into two types, namely: the gripping type and
the lifting type.
The gripping type article handling systems invariably
include a gripping mechanism that attaches to the top of an
article, such as a box, and moves said article from one
position and/or place to the next. Such gripping mechanism
may include suction cups to which a source of negative
pressure is applied to effectuate attachment to the article.
Alternately, attachment may occur by magnetic means and/or
mechanical means. U.S. Patents 4,266,905; ~,299,533;
4,242,025 and 4,392,766 describe gripping mechanisms in
which negative pressure is used to effectuate attachment.
On the other hand, the lifting type article handling
sys-tems may be considered to be reminiscent of the ~ork lift
devices used in warehouses to move articles. Such devices
consist of a pair of spaced forks or lifting elements which
are inserted under the bottom side o the article. As a
result, the article sits on the forks and is relocated.
3 ~5$~
Altilough the above identified ar-ticle handling systems
work well for -the intended purpose, they all handle the
boxes from either the top side or the bottom side and as
such are no-t sui-table for use on the type o~ automated
rnanufacturing lines wherein the components for manufacturing
the product are provided in boxes (such as cartons) having
removable covers (shoe box s-tyle). Since the top covers are
loose, such car-tons cannot be handled and/or depalletized by
holding onto the covers.
Summary of the Invention
It is therefore a general object of the present
invention to provide a more efficient article manipulating
system than was heretofore possible.
It is another object of the present invention -to
provide an article manipulating system that handles articles
such as boxes from the sides and bottom.
According to one aspect of the invention there is
provided an article manipulating device for use wi-th a robot
comprising, a frame operable for coupling said device to the
robot, a lifting means being connected to said frame and
operable for supporting an article thereon, and a gripping
means being coupled to said frame; said gripping means being
constrained to move in a plane substantially parallel to the
lifting means to grip the article and placing said article
on the lifting means.
~s~
~ ccording to another aspect of the invention there is
provided an article handling apparatus comprising, a mounting
plate, a frame haviny spaced members connected to said
plate, a lifting mechanism connected to the frame, and an
air cylinder mounted to the lifting mechanism; said air
cylinder including a piston with a picking device connected
thereto and being constrained to move in a plane substantially
parallel to the lifting mechanism.
The foregoing features and other advantages of this
invention will be more fully described in the accompanying
drawings.
Brief Description of the Drawings
Fig. 1 represents a pictorial view of the article
manipulator according to the teachings of the present
invention.
Fig. 2 shows a side elevational view of the subject
article manipulator with the picker mechanism extended.
Fig. 3 shows a side view of the subject article manip-
ulator with the picker mechanism retracted. The figure also
shows how an article is handled from the sides and bottom.
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~9~5003 5
FicJ. ~ shows a uni~ersal jolnt for moun-ting the picker
mechanism.
Fig. 5 shows a device Eor adjusting the picker mecha-
nism.
Fiy. 6 shows an air logic schematic for controlling the
article manipulator.
Fig. 7 is a flow chart showing the overall operation of
the system.
The article handling apparatus 10 includes a frame
assembly (12A, 12B, 28A and 28B), a gripper mechanism 14, a
lifting device 16, a set of sensors (18, 20 and 22) ~or
sensing the positlon of the article manipulator relative to
an article and a second set of sensors (24 and 26, Fig. 2)
for sensing when an article is securely held by the article
manipulator. In operation, a general purpose robot (to be
described hereinafter) positions the lifting member 16
relative to the bottom surface of a box to be transported.
The gripper mechanism 14 is extended beyond the extremity of
the lifting de~ice to grip the box and pull the box onto the
lifting device (Fig. 3). With the box being secured on the
~25 lifting members by the gripper mechanism, the box is then
moved from the pallet (not shown) to the conveyor line (not
shown). The box as it progresses down the line will be
accessed by a robot to remove parts and fabricate a product.
The product is then loaded into the box and the box is
~30 palletized for shipping to respective customers.
Referring now to Figs. l~and 2, common elements will be
identified by the same numeral. The frame assembly in-
cludes a top section 28 and lower section 12. The top
section 28 includes a pair of arcuate members 28A and 28B
i that are fastened in spaced relationship to a mounting plate
32. The mounting plate in turn is adjustably mounted to the
wrist of the robot tool mounting plate (not shown). Al-
though the article manipulator of the present invention can
be used with any general purpose industrial robot in the
~985003 6
~256~313.3
preferred embodiment oE this invention the article manipula-
tor was attached to the -tool mounting plate of a the Cincin-
nati Milacron T3-~76 Robot.
A plurality of slots identified by numerals 34, 36, 38
and 40 are fabricated on the lower extremity of the member
28A. A similar set of slots (not shown) are fabricated on
member 28B. As will be explained subsequently, these slots
serve a dual purpose. The slots are used to fasten the top
section of the frame to the lower section (to be described
hereinafter) and provide an adjustment mechanism so that the
lower section of the frame can be adjusted relative to the
upper section.
The lower section 12 comprises of irregularly shaped
members 12A and 12B. Each of the members is fabricated from
flat light-weight metal such as aluminum. Member 12B is
fabricated with a plurality of circular holes some of which
are identified by numerals 42, 44, 46, 48, 50 and 52. A
similar set of holes (not shown) is fabricated on the upper
extremity of member 1 2A. The holes on members 1 2A and 12B
are used for fastening the lower section of frame 12 to the
upper section 2~. To this end, a plurality of screws, some
of which are shown in Fig. 1, are inserted into the holes
located on the respective members of the frame. By tighten-
ing respective nuts on the respective screws, the lower
section of the frame is connected firmly to the upper
section. ~ bracket member identified by numeral 54 is
traversely fastened to the upper members at the point
~30 whereat the lower frame joins the upper ~rame. The function
of the traverse strap 54 is to provide structural strength
ko the frame assembly.
Still referring to Figs. 1 and 2, the lifting device 16
is substantially U-shaped with a pair of spaced lifting
forks or members 16A and 16B, respectively. A traverse
member 54 interconnects the lifting fork at its rearward
extremity. The lifting device 16 is connected to the lower
frame section 12. A hinged means 56 is fabricated in each
of the lifting members 16A and 16B, respectively. In the
.
RA9~5003 7 ~5~
figure, only one of -the hinges is shown, it being understood
that a simi]ar hinge is provided in lifting member 16A. The
front extremities of the lifting members are be~eled. ~s a
result of the beveling and hinges associated with each
lifting member, the lifting device 16 can get relatively
close to a pallet, (not shown) carrying carton boxes of
parts, and approach -the carton at an angle without causiny
the main body of the bottom section of the article handling
mechanism to hit the pallet.
Referring to Figs. 1, 2 and 3, the gripper mechanism 14
is mounted by a paix of mounting brackets, only one of which
is shown and is identified by numeral 56 to member 5~. The
function of the gripper mechanism 14 is to grip a bo~ from
the side (Fig. 3), separate said box from a pallet load of
boxes (not shown), and place the box on lifting devices 16A
and 16B, respectively. The mounting brackets are pivotally
coupled to slide mount means 58. The slide mount means 58
- is slidably coupled to air cylinder 6Q. By slidably coup-
ling the air cylinder 60 to slide mount means 58 the air
cylinder 60 (to be described subsequently) can be adjusted
in the direction shown by arrow 62. As a result of this
adjustment feature, the gripper mechanism 14 can be made to
handle variable size boxes.
With reference to Figs. 2 and 3 for the moment, the air
cylinder 60 is adjusted so that the slide mount means 58 is
positioned at a point on the air cylinder that enables the
gripper mechanism 14 to extend vacuum cups 62 and 64,
respectively, beyond the tips of lifting members 16A and
16B, respectively. Likewise, in Fig. 1, the air cylinder 60
is adjusted so that the slide mount means 58 is at the
e~treme front end of the air cylinder 60. With this adjust-
ment the reach of vacuum cups 62 and 64 is less than that of
Figs. 2 and 3. The adjustment is effectuated by loosening a
plurality of screws, two of which are identified by numberal
57, and sliding a plurality of mounting rods, two of which
are identified by numerals 78 and 80, relative to the slide
mount means. As will be e~plained subsequently, the mount-
ing rods are part of he cylinder
6~1L3
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385003 ~ 8
Still referring to Figs. 1, 2 and 3, air cylinder 60 is
a conventional off-the-shelf item. It is used to position
vacuum cups 62 and 64 relative to a box. The use of such
air cylinders has a positioning device is well known in the
prior art. Therefore, the details of the air cyllnder will
not be given. Suffice it to say that the air cylinder
includes a cylinder pGrtion with a front block 66 and a rear
block 68. Both the front and the rear blocks are fabricated
with four openings identified in block 66 with numerals
70-76 (Fig. 1). A similar set of holes is also provided in
block 68. Four rods, two of which are shown in Fig. 3 and
are identified by numerals 78 and 80, are mounted in the
respective openings. ~ piston rod identified by numeral 82
is constrained to move within the cylinder in the direction
shown by arrow 84. One end of the piston rod ~not shown) is
trapped inside the cylinder and is fitted with a piston (not
shown). By forcing air on the appropriate side of the
piston, it is made to extend in the direction shown by arrow
86 or it can be retracted in the direction shown by arrow
88. Although any off-the-shelf conventional air cylinder
can be used to perform the recited function in the preferred
embodiment of this invention, a P~ID 10-inch non~rotating
cylinder was used.
As was stated previously, the air cylinder 60 is
adjusted relative to slide mount means 58. To this end a
relatively large opening having a size that will accept the
width of the air cylinder 60 is fabricated in the center of
the slide mount means. Four small holes similar to those
fabricated in front block 66 and rear block 68 are fabri
cated in slide mount means 58. The front block 66 is
removed from the air cylinder and the respective rods are
passed through the respective holes in slide mount means 58.
The front block 66 is then refitted. Referring to Fig. 5
for the moment, there is shown an adjustment feature which
enables the gripper mechanism to be adjusted in the vertical
plane. An adjustment means, preferably a screw identified
by numeral 90, is threaded through cross member 5~. The
leading end of the screw is in contact with front block 66.
By turning the screw the front block and attached mechanism
RA9~5003 9 ~2S6~3
are made to be adjusted upward or downward in a vertical
plane identi~ied by numeral 65.
Referring now to Figs. 1, 2, 3 and 4, a mounting
bracket identified by numeral 92 is connected to piston rod
82. A swivel block 94 (Fiys. 1 and ~) is pivotally mounted
to mounting block 92. A manifold 96 is pivotally mounted to
swivel block 94. As will be explained subsequently, the
swivel block and pivotally coupled manifold operate as a
universal joint to enable vacuum cups 62 and 64 to adjust
relative to the shape or position of a box to be picked.
Two vacuum cups 62 and 64 are mounted via mounti~g posts 98
and 100 to the manifold. Although two vacuum cups are shown
and described herein, this should not be construed as a
limitation on the scope of the present invention since it is
within the skill o one skilled in the art to utilize a
different number of vacuum cups to provide the means for
picking a box.
The invention further includes a air/vacuum system
which provides vacuum and air ~or proper operation of the
picker mechanism. With reference to Figs. 1 and 3, the
air/vacuum system includes a vacuum generator identified by
numeral 102. The vacuum generator 102 is a conventional
device that generates a vacuum when air is allowed to enter
into the device. Since this is a well-known conventional
device, details of its operation and construction will not
be given. Suffice it to say that in the preferred embodi-
ment of this invention a PIAB vacuum generator was used.
An interconnecting hose identified by numeral 104
interconnects the side of the generator which provides
negative pressure to manifold 96. Similarly, air from an
air generating source ~not shown) is conveyed through tube
106 to the positive pressure side of the generator. The
RA985003 10 ~ 13
vacuum ge~nerator provides vacuum ~negative pressure) for
suc~ion cups 62 and 64, respectlvely.
~s will be explained subsequently, by activating
solenoid valve (not shown) with signals from the robot's,
controller air is admitted into -the vacuum generator 102 and
as a result a vacuum is created in the manifold 96 and
ultimately to suction cups 62 and 64, respectively.
As stated previously, the air cylinder 60 requires air
for proper operation. To this end, two fluid conduction
means identified by numerals 108 and 110 (Figs. 2 and 3)
interconnect the air cylinder 60 to a suitable air supply
(not shown). When the air in conducting means 110 is
activated, the piston is forced to be extended and moves in
the direction shown by arrow 86, Fig. 1. Similarly, when
the air in conducting means 108 is activated, the piston is
retracted in the direction shown by arrow 88.
Fig. 6 shows an air logic schematic for the air/vacuum
system. The air logic schematic provides vacuum~air supply
to vacuum cups 62 and 64 and air cylinder 60, respectively.
Air is supplied with a pressure of approximately 80-90 psi.
The output line from the air supply is coupled through a
solenoid 108. The solenoid is an off-the-shelf air solenoid
which functions as a on-off switch and is activated by a
signal outputted from the robot's control. In the preferred
embodiment of this invention, the solenoid was ~abricated by
Schrader, Inc. The output from the on-off solenoid switch
108 is fed into a vacuum off-on solenoid switch 110 and a
double-throw solenoid 112. The double-throw solenoid 112
' controls the air cylinder 60. The double-throw solenoid is
provided with exhaust valve 114 and 116, respectively. Each
exhaust valve provides a means for bleeding air from the
~35 piston when it is about to move in the opposite direction.
Likewise, solenoid 110 provides the on-off air to vacuum
; generator 102. The output from vacuum generator 102 is
coupled through vacuum switch 114 to the vacuum cups 62 and
64. ~s will be explained subsequently, whenever vacuum is
applied to the cups, the switch will output a signal when
'
RA9~5003 11 ~56~3
vacuum is nlade between the cup and a bo~. The output from
the vacuum switch is utilized by the robot controller to
move the bo~.
~s was stated previously, several sets of sensors are
provided to sense the position of the lifting mechanism
relative to the box. Two proximity sensors identified by
numerals 18 and 20 (Figs. 1 and 23 are located on top of the
vacuum maniEold 96 and on the side of lower frame 12.
Sensor 18 is used to determine whether there is a carton box
in the path of the gripper in the hori~ontal plane when the
gripper is searchiny for a carton and it is simultaneously
used to signal the robot's controller to turn on the vacuum
generator in the event the carton is found. This is done by
the robot controller generating a signal to solenoid 110,
Fig. 6.
Likewise, sensor 20 (on the side of the lower frame) is
mounted in the vertical plane and is used to determine (in a
search procedure to be described hereinafter) if the carton
is where it should be (that is, enough boxes ln the stack)O
That initial point is used as a reference point for the
robot's controller to determine where the bottom of each
carton in the stack should be, thus allowing the arms of the
lower frame to be located at the level of the bottom of the
carton. Reed switch 114 (Fig. 3) senses when a carton is
fully seated on the lifting legs and outputs a signal on
; conductor 116. To this end, a magnetic ring (not shown) is
fitted on the piston (not shown) which is attached to the
extreme end of piston 82 and lies within air cylinder 60.
Because the reed switch is situated at the extreme back of
the cylinder, whenever the magnetic ring passes the reed
switch a signal is generated and outputted on conductor 116.
The signal indicates that the picking mechanism is fully re-
tracted and the carton is properly seated on the lifting
mechanism (that is lifting members 16A and 16s). ~t this
point the robot controller generates a signal which moves
the article handling mechanism and the attached box, Fig. 3,
to a predetermined point, usually to a conveyor belt (not
shown).
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RA985003 12
Another set of sensors to be described shortly is
mounted a-t -the junction wllere lower frame 12 joins upper
frame 28 (Fi~. l). The function of the sensors is to detect
abnormal motion in the gripper which would result from
striking an object in a way that would damage the gripper.
To this end a light emitting device 22 is mounted on one
section of the lower frame, say side 12B, and a light
receiving device (not shown) is mounted on the opposite
frame 12A in the hole identified by numeral 116. Since the
light generating device 22 and the light receiving device
(not shown) are mounted diametrically any motion in the
lower frarne, be it upward or arcuate, breaks the beam
between the light receiving device and the light emitting
device resultiny in a signal which is generated and fed to
the robot controller. As a result of this signal, the
article handling mechanism is shut down. In the preferred
embodiment of this invention the frames are designed with
slots that allow approximately 800-inch of upward travel by
~ the lower frame 12 and/or a 15 upward tilt of the lower
frame. The sensor's light beam will be broken by the
passing of the lower frame over the mounting holes of the
sensors. The breaking of the beam signals the robot con-
troller to stop all program activity and there~ore all
motion. This prevents unnecessary damage to the gripper by
cartons, etc. which are encountered out of place by the
gripper. ~lthough specific measurements are given, this
should not be construed as a limitation on the scope of the
invention since it is within the skill of the art to design
other tolerances without departing from the scope of the
present invention.
Fig. 7 shows a flow chart of the process steps which
must be performed in order for a box to be depalletized and
placed on a conveyor (not shown). The flow chart includes
~35 the functions which the robot controller (not shown) must
perform in order to provide the motion control necessary for
positioning the box. The robot controller utilizes the
; signals which are generated from the above described sensors
to position the article handling mechanism. The programming
of such controllers is well known; therefore, the detailed
~985003 l~ S6~3
code which is ~ritten in the controller in orcler to perform
the process steps outline~ in the flow chart is not ~iven,
it being understood that it is well within the skill of one
skilled in the ar~ of programming to utilize the information
set forth in the flow chart to provide the necessary code
for controlling the robot. The first step in the process
is identified in block 116. The block signifies the begin-
ning of -the process. The program then descends into block
118 where the gripper mechanism is transferred to a zone
above the pallet carrying the boxes. The program utilizes
the vertical sensor (previously described) to search the
vertlcal plane to make sure there is a box. If no box is
discovered (block 122), the program then enters block 124
where it is stopped and then into block 126 where it waits
for another instruction.
If a bo~ is sensed in the vertical plane (block 122),
the program -then descends into block 130 where the robot
moves the gripper mechanism and aligns the lifting members
with the bottom surface of the first row of boxes on the
pallet. The program then descends into block 132 where it
searches the horizontal plane for the presence of a box via
the horizontal sensor (previously described above). If no
box is sensed in the horizontal plane lblock 134~, the
program then enters block 136 where it stops and then to
block 138 where it waits for an instruction.
If a box is sensed in the horizontal plane, the program
-then enters block 1~2 where it extends the piston and turns
the vacuum. The program then enters block 144 where it
checks to make sure the vacuum is made between the vacuum
cups and the box to be picked. This checking is done by
vacuum switch 24 (Fig. 1). If there is no vacuum, the
program enters block 146 where it stops and then block 148
where it waits for an instruction.
If vacuum is made (block 144), the program then enters
block 152 where the piston is retracted and then to block
154 where the box is moved from the pallet to a new loca-
tion. The program then turns the vacuum off block 156 and
~9850~3 1~ S~3
then returns for a ne~t search, that is, to remove another
~o~ (block 15S). The process continues until all boxes are
removed from -the particular pallet and the proyram stops the
device (block l60).
s
Operation
In operation, the program controlled robot u-tilizes
signals output-ted from the above described sensors to
orientate the gripper mechanism so that the forks or lifting
members are oriented in a plane parallel to the boxes bottom
side. The piston of the air cylinder with its attached
vacuum cups are extended beyond the forks. At a specified
distance from the boxes vacuum is applied to the suction
cups l~hen the vacuum is made between the suction cup and the
box, a signal is ou-tputted from the vacuum switch 24. The
robot controller then activates the air supply which causes
the piston to be retracted to pull the carton box onto the
forks. The carton is then lifted free of the stack on the
~20 pallet.
The ends of the forks are hinged to allow the gxipper
to operate on the surface of the pallet or slip-sheet. By
hinging the lifting members, the gripper can be tilted to
;25 allow only the hinged portion of the lifting members to
contact and to follow the surface of the pallet or
slip-sheet while approaching the bottom cartons of a load.
The gripper can be adjusted forward and backwards relative
to its mounting plate and can be open or closed in height to
allow for larger or smaller boxes.
