Apparatus for palletizing bundles of paper

An apparatus for stacking irregular height bundles of paper onto a shipping pallet. Height detectors measure bundles traveling on a conveyor. The height data is utilized by a computer system to control an accumulator to accumulate and stack bundles to a predetermined height and then move the bundles to a storage compartment. The computer instructs a robot to move the stored bundles and place them in a compartmentalized guide box on a pallet in a substantially level predetermined layer height.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention is directed to a method and apparatus for handling, 
moving and stacking bundles of paper such as magazines. More particularly, 
the present invention is directed to a method and apparatus for 
efficiently handling and moving irregular-height bundles of strapped, 
banded, loose, or shrink wrapped magazines from a postal routing bundling 
machine and evenly stacking the bundles magazines onto a pallet. 
In the magazine publishing and distribution business, magazines are 
prepared for shipment through the United States Postal Service by placing 
the names and addresses of the subscribers on the magazines. The Postal 
Service prefers to receive these magazines in presorted bundles arranged 
according to postal routing and gives a discount for bundles so arranged. 
Postal routing refers to zip code, carrier route, walk route, etc. 
A bundling machine is used to bundle magazines according to postal routing. 
Depending on the number of magazines going to a particular postal route, 
the magazine bundling machine may bundle more than one bundle of magazines 
per postal route, however, there may be only enough magazines for a 
smaller bundle. Therefore, a magazine bundle may be between a certain 
minimum and maximum height. Generally, the height of a magazine bundle may 
be from two inches to a maximum of seven inches in height. 
After the magazines are bundles according to postal routing, the bundles 
may be placed on pallets for handling by the Post Office. These bundles 
were placed by hand on the pallet, with the object of trying to even out 
the level of the stacked bundles for stable shipping. However, magazine 
bundle heights being unpredictable, caused many problems for achieving 
even pallet stacking levels necessary for stable shipment. Much time was 
spent in trying to stack the magazine bundles as evenly as possible, but 
due to time constraints and the skill levels of shipping personnel, stable 
pallet loads were not always achieved. 
SUMMARY OF THE INVENTION 
The present invention is directed to an apparatus that receives magazines 
bundles by postal routing from a bundling machine. The magazine bundles 
arrive on a conveyor wherein the height of each bundle is measured and 
recorded in a digital computer memory. Next the bundles arrive at an 
accumulator which guides the bundles into a collection box wherein 
multiple bundles are stacked. When the magazine bundles are stacked to a 
height determined by the computer program of the invention, the magazine 
bundles contained therein are pushed into a shuttle box by an air actuated 
ram which clears the collection box so that the next set of magazine 
bundles may be similarly collected therein. 
The shuttle box is adapted for receiving an end effector. The end effector 
fits on top of the shuttle box and receives the magazine bundles contained 
therein. The magazine bundles are pushed up and into the end effector by 
means of an air actuated elevator. The bundles are held in the end 
effector by fingers located at its bottom. A computer controlled robot 
moves the end effector to a predetermined location on the pallet at which 
time the end effector fingers release the bundles. The end effector may 
accept up to 14 inches of magazine bundles from the shuttle box. The end 
effector may be rotated 90.degree. for interlocking of the bundles. In 
addition, the end effector may be rotated 180.degree. in order to place 
the magazine bundles in such as way as to balance tapered bundle loads. 
The computer program of the invention determines where the end effector 
places the magazine bundles on the pallet. The computer program keeps 
track of where these bundles are placed on the pallet and attempts to 
stack the bundles so as to create a layer of bundles wherein the top 
terrain of the stack is mostly flat or may be slightly concave toward the 
middle. The purpose of obtaining a flat or slightly concave toward the 
middle terrain on the top of a layer of stacked magazine bundles is to 
create a stabilized base for the stacking of pallets one on top of 
another. 
Magazines may not stack flat due to the method of binding or card inserts 
contained in each magazine, thus, a bundle may bulge in the middle or at 
an edge. This bulge may cause uneven stacking of the bundles with the 
possibility of the bundles toppling off of the pallet. Heretofore, workers 
held the bundles in place while plastic shrink wrap was placed around the 
perimeter of the magazine bundles to hold them in a mostly vertical 
position on the pallet. 
The invention solves the problem of unstable stacks by using a guide box to 
help keep the magazine bundles being stacked from toppling over during the 
development of a bundle layer. The guide box has a compartment for each 
location on the pallet. Each compartment is open at the top and bottom of 
the guide box allowing the stacked bundles to pass through from the end 
effector to the pallet location The computer controlled robot moves the 
end effector containing the bundles to predetermined locations on the 
pallet until all locations are filled to a height giving a mostly level 
layer. The pallet is supported by a scissor lift that lowers the pallet a 
distance necessary to bring the just completed layer out of the guide box. 
While the pallet is being lowered, a stretch wrapping device travels 
around the perimeter of the pallet wrapping the just completed layer of 
magazine bundles as they emerge from the bottom of the guide box. The 
stretch wrap prevents the bundles from toppling over. 
The magazine bundle layers may be up to 14" high and there may be four 
layers of bundles contained on the pallet. In addition, for equal height 
bundles, e.g. newsstand distribution, the system of the invention may 
shift the location of the guide box relative to the just completed layer 
so that the next layer of magazines stacked thereon interlock giving a 
more stable pallet load. Another embodiment of the guide box has some of 
the location compartments turned 90 degrees to improve the interlocking of 
layers. The guide box may be shifted horizontally so as to offset the 
presently forming layer locations from the prior layer locations, thus, 
overlapping the different layers for equal height bundles. 
The computer system uses control contour zones which are the perimeter and 
the inner locations of the pallet. It is important that the outer 
perimeter bundles be of a height slightly greater than or equal to the 
inner bundle heights so that the next layer on top will maintain its 
stability without toppling over the edges of the pallet. Therefore the 
computer will attempt to place a stack in each location such that the 
accumulated height of that location will closely match the instantaneous 
ideal height for that location. This may not always be possible. However, 
by judicial selection of the locations, the system of the invention may 
get the contour of a layer within an acceptable tolerance. So long as the 
outer perimeter of the stack terrain is slightly above the inner bundle 
locations, then the magazines will stack in a stable fashion. 
The computer system of the invention keeps track of the cumulative bundle 
height of each location and if the inner bundle locations of the first 
layer are of such height to be significantly less than the outer perimeter 
location heights, then the computer system will remember these heights and 
add the second layer of bundle heights to compensate for the concavity 
towards the middle and will, thus, have the second layer top terrain more 
level than the first layer. 
Several options may be used to improve the efficiency of the stacking 
operation. One of them is to have a location toward the middle of the 
pallet that is left empty until all of the other locations of a bundle 
layer are completed. The problem occurs sometimes when a bundle comes in 
that is so large that it cannot be properly placed in the existing 
topology of the then existing bundle layer, i.e., there are no locations 
that will accept the bundle height. This occurs when a bundle is near the 
maximum of six or seven inches in height. The program of the computer 
system is such that a bundle layer height is obtained by stacking each 
magazine bundle until a certain maximum level is reached. Thus, if only 
four inches are left to complete a stack and a six inch bundle comes in, 
this bundle cannot be placed on the stack because it would exceed the 
maximum height of the bundle layer. 
A second option of the invention comprises the use of at least one holding 
station where a magazine bundle may be shunted off of the normal order of 
arrival from the magazine bundling machine wherein the bundle so shunted 
into the holding station may be retrieved later when an available layer 
location is determined. Thus, having at least one holding station allows 
the computer system to shunt off a fairly tall, i.e., six or seven inch, 
magazine bundle for stacking on the next layer. 
A third option of the present invention uses a deep hole in the middle of 
the pallet stacks that is twice as deep as a normal layer height. This 
gives the system of the invention more ways to accept bundles of unusual 
height. Therefore, the use of a holding station and a deep hole in the 
middle of a stack allows the computer system of the invention to place 
magazine bundles of heights greater than would be possible without either 
of the above options. 
An object of the present invention is to stack a pallet with bundled 
magazines according to the postal routing in mostly level layers having 
stable loading characteristics that may be enhanced by a stretch wrap on 
the outer perimeter of the magazine bundle layers. 
A further object of the present invention is to interlock each bundle layer 
by offsetting the orientation of the magazines thus improving the load 
stability of the pallet containing the stacked bundles. 
Another object of the present invention is to use a guide box to prevent 
uneven magazine bundles from toppling over while stacking on a pallet. 
Yet a further object of the present invention is to use a holding station 
to retain a bundle having a height in excess of what may be possible to 
stack in a layer but could be placed in the next layer of the stack. 
Still another object of the present invention is to use a deep hole in the 
middle of a stack allowing placement of magazine bundles of heights 
greater than would be possible otherwise. 
Other and further objects, features and advantages will be apparent from 
the following description of the preferred embodiment of the invention, 
given for the purpose of disclosure and taken in conjunction with the 
accompanying drawings.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
The present invention provides an apparatus and method for stacking bundles 
such as magazines bundled by postal routing onto a pallet for shipment by 
the United States Post Office. Referring now to FIGS. 1 and 2, the 
reference numeral 40 indicates generally the apparatus of the present 
invention. The apparatus 40 includes a bundle conveyor 50 which receives 
the bundled magazines having the same postal routing from a magazine 
bundling machine (not shown) and passes these bundles through a height 
gauge 52, as more fully described hereinafter, wherein the height of each 
bundle is measured, then an accumulator 54 guides and properly orients the 
bundles for collection in a collection box 56. After at least one bundle 
of magazines is collected in the collection box 56, the magazines are 
moved to a shuttle box 58. The shuttle box 58 is adapted to receive an end 
effector 60 attached to a robot 62. The robot 62 places the end effector 
60 on top of the shuttle box 58 so that the magazine bundles contained in 
the shuttle box 58 may be pushed up into and held by the end effector 60. 
The robot 62 then moves the end effector 60 containing the magazine 
bundles to a pallet 90 where the bundles are placed thereon. 
Referring now to FIG. 4, a magazine bundle 86 moves in direction 88 along 
conveyor rollers 110 into the upper portion of accumulator 54. Referring 
to FIG. 5, the bundle 86 is held in the upper portion of the accumulator 
54 when first holding fingers 112 are closed. When the fingers 112 are 
open, bundle 86 drops into the lower portion of the collection box 56. 
Then fingers 112 close in anticipation of receiving the next bundle 86. 
More than one bundle 86 may be collected in the lower part of the 
collection box 56. When a certain height is reached by the bundle or 
bundles contained therein, a pushing ram 114 moves the bundles 86 past 
open second holding fingers 116 into the shuttle box 58. Fingers 116 close 
and shuttle elevator 118 lifts bundles 86 into the end effector 60. Third 
holding fingers 120 close and, thus, retain the bundles 86 in the end 
effector 60 when the robot 62 moves the end effector and bundles contained 
therein to the pallet 90. 
Referring back to FIG. 1, a robot control panel 64 contains an electronic 
computer control system 92 for controlling the robot 62, and system panel 
66 contains an operator interface 96 and second computer system 94 for 
determining placement of the magazine bundles on the pallet 90. The 
program of computer system 94 controls the placement of the magazine 
bundles by using the height of each bundle obtained from height gauge 52 
to determine a placement location on the pallet 90. As illustrated in 
FIGS. 3a to 3c, the height gauge 52 may have infrared receivers 100 and 
infrared transmitters 102 located at different heights so that a bundle 
passing through height gauge 52 on conveyor 50 will block the transmission 
of the corresponding infrared transmitters 102 from being received by the 
corresponding receivers 100. Thus, the bundle height may be easily 
measured and sent to the computer system 94. 
The computer program uses the height information from the height gauge 52 
in determining where the bundles are placed on the pallet 90. The computer 
program of computer system 94 causes the robot 62, by means of its control 
computer 92, to stack the bundles so as to create a layer of bundles 
wherein the top terrain of the stack is mostly flat or may be slightly 
concave toward the middle. The purpose of obtaining a flat or slightly 
concave toward the middle terrain on the top of a layer of stacked 
magazine bundles is to create a stabilized base for the next layer of 
bundles. 
Magazines may not stack flat due to the method of binding or card inserts 
contained in each magazine, thus, a bundle may bulge in the middle or at 
an edge. This bulge may cause uneven stacking of the bundles with the 
possibility of the bundles toppling off of a pallet. Heretofore, workers 
held the bundles in place while plastic stretch wrap was placed around the 
perimeter of the magazine bundles to hold them in a mostly vertical 
position on a pallet. 
The present invention solves this problem by using a guide box 68 to help 
keep the magazine bundles being stacked from toppling over during the 
development of a bundle layer. Referring now to FIG. 6, the guide box 68 
has compartments or pocket locations 98 for all locations on the pallet 
90. Each compartment 98 is open at the top and bottom of the guide box 68 
allowing the stacked bundles to pass through from the end effector 60 to 
the locations on pallet 90. Movement of the robot 62 is controlled by 
computer 92 after receiving directions from computer 94 and moves the end 
effector 60, containing the bundles, to predetermined locations on the 
pallet 90 until all locations are filled to a height giving a consistently 
level layer. 
As best illustrated in FIG. 2, the pallet 90 is supported by a scissor lift 
82 that lowers the pallet 90 a distance equal to the height of the just 
completed layer. While the pallet 90 is being lowered, a stretch wrapper 
76 travels around the perimeter of the pallet 90 wrapping the just 
completed layer of magazine bundles as they emerge from the bottom of the 
guide box 68. The stretch wrap prevents the bundles from toppling over. 
Each magazine bundle layer may be up to 14" high and there may be four 
layers of bundles contained on a pellet. In addition, the system of the 
invention may shift the location of the guide box 68 relative to the just 
completed layer so that the next layer of magazines stacked thereon 
interlock thereby giving a more stable pallet load. FIGS. 6 and 7 
illustrate non-interlocking and interlocking guide box designs, 
respectively. Several compartments 98a of the guide box 68a illustrated in 
FIG. 7 are turned 90 degrees to improve the interlocking of layers. The 
end effector 60 containing the bundles may be turned 90 degrees by the 
robot 62. The guide box may also be shifted horizontally by the robot 62 
so as to offset the presently forming layer locations from the prior layer 
locations, thus, overlapping the different layers. 
Referring now to FIG. 1, a holding station 99 is illustrated. The holding 
station 99 allows a magazine bundle to be shunted off of the normal order 
of arrival from the magazine bundling machine (not shown) wherein the 
bundle so shunted into the holding station 99 may later be retrieved when 
an available layer location is determined. Thus, having at least one 
holding station 99 allows the program of the computer system 94 to shunt 
off a fairly tall, i.e., six or seven inch, magazine bundle for stacking 
on a subsequent layer. 
COMPUTER SOFTWARE CONTROL PROGRAM 
The present invention includes a computer system 94 having a program with a 
novel set of instructions to control the operation of receiving magazine 
bundles from a bundling machine (not shown), storing the measured height 
of each bundle and then determining how many bundles are to be held in the 
collection box 56 before transferring the bundles to the shuttle box 58. 
The system of the invention moves the bundles from the collection box 56 
to the end effector 60. The end effector 60 then places the bundles on the 
pallet 90 is such a manner as to create a layer whose top terrain will be 
stable for the next layer placed thereon. 
The program of the computer system 94 uses control contour zones which are 
the perimeter and the inner locations of the pallet 90. It is important 
that the outer perimeter bundles be of a height slightly greater than or 
equal to the inner bundle heights so that the next layer placed thereon 
will maintain its stability without toppling over the edges of the pallet 
90. Therefore the computer will attempt to place a stack in each location 
such that the accumulated height of that location will closely match the 
instantaneous ideal height for that location. 
This may not always be possible. However, by judicial selection of the 
locations, the program controls the contour of a layer within an 
acceptable tolerance. So long as the outer perimeter of the stack terrain 
is slightly above the inner bundle locations, then the magazines bundles 
will stack in a stable fashion. 
The program of computer 94 keeps track of the cumulative bundle location 
heights and if the inner bundle locations of the first layer are of such 
height to be significantly less than the outer perimeter bundle location 
heights, then the computer system will remember these heights and add the 
second layer of bundle heights to compensate for the concavity towards the 
middle and will, thus, have the top terrain of the second layer more level 
than the first layer. 
Referring generally to FIGS. 8 through 15, schematic block diagrams are 
illustrated of the control program of the present invention. Step 400 
begins the main loop 400 (FIG. 8) and step 402 initiates setup of system 
operating parameters such as layer height, stack offset, etc. Step 404 
does a one time initialization then step 406 assumes that there is a new 
load and zeros all pocket height registers in the program. Next step 408 
sets up a new target height for each pocket location of the pallet 90. 
Step 410 tests for a bundle passing through the height gauge 52. If a 
bundle is present then steps 412 and 414 measure the bundle height and 
place it in a bundle height queue, respectively. If step 410 determines 
that a bundle is not present at height gauge 52 then step 418 determines 
if the bundle is entering the accumulator 54. 
Next step 416 determines if the bundle just measured in step 412 will cause 
the bundle height accumulator to overflow. If overflow would occur then 
step 416 causes the program of computer 94 to jump to step 426 (FIG. 11) 
more fully described hereinafter. If no overflow occurs then step 418 
determines if the bundle is entering the accumulator 54. If a bundle is 
not entering the accumulator 54 then step 424 tests whether the present 
accumulation of bundles is complete. When a bundle enters the accumulator 
54, steps 420 and 422 accumulate the entering bundle and remove it from 
the queue, respectively. A bundle is accumulated when it enters the upper 
part of collection box 56 (FIGS. 1 and 2) and drops past open fingers 112 
(FIG. 5) into the lower part of the collection box 56. 
The bundles accumulate in this fashion until the height of the bundles are 
within a predetermined tolerance. Step 424 determines whether the 
accumulated bundles are within the required height tolerance range. If the 
accumulated bundles have not yet reached the predetermined height then 
step 424 causes the program of computer system 94 to jump to step 432 
(FIG. 12) more fully described hereinafter. When the accumulated bundles 
are within the predetermined height, steps 424 and 426 cuase the computer 
system 94 to open fingers 116 and have ram 114 push the collected bundles 
from the lower part of collection box 56 into the shuttle box 58 (FIG. 5). 
Step 428 determines where the accumulated bundles are to be placed on the 
pallet 90. Referring now to FIGS. 14 and 15, step 428a starts a subroutine 
that makes this determination. A purpose of this subroutine is to make a 
layer of magazine bundles with as even a top terrain as possible. This 
subroutine calculates the height discrepancies for each pocket location 98 
on the pallet 90 and directs the robot 62 to place the accumulated bundles 
into a pocket location resulting in the smallest discrepancy for the 
desired layer height. 
Steps 502 and 504 initialize the subroutine by presetting the lowest 
discrepancy to a high value and starting the comparison calculations at 
the first pocket location, respectively. Steps 506 and 508 calculate the 
height discrepancy that will result if the bundles are placed in the 
chosen pocket location. Step 510 determines if the height discrepancy 
predicted is the smallest so far and, if so, step 512 stores the 
discrepancy value and pocket location in the computer system 94 memory for 
use in subsequent height comparisons using other pocket locations. 
If the calculation of height discrepancy does not result in the lowest 
value than step 514 increments the program to the next pocket location and 
step 516 determines if the last pocket location of the stack has been 
evaluated. If the last pocket location has not been evaluated step 516 
causes step 506 to begin the steps above for the next pocket. The 
subroutine 428a continues in this manner until all pockets are evaluated 
with the current accumulated bundles for minimum height discrepancy of the 
layer. When the last pocket is so evaluated and the best choice of a 
pocket location is made, step 516 returns control back to main program 
step 430 (FIG. 11). Step 430 zeros the accumulation register in 
anticipation of the next accumulation of bundles. 
Step 432 determines whether the bundles are in storage in the shuttle box 
58. If step 432 determines that the bundles are in storage, then step 434 
checks if the robot 62 is ready to receive the bundles. When the robot 62 
is ready, step 436 tells the robot computer control 92 which pocket 
location to place the bundle. Step 438 causes the shuttle elevator 118 to 
push the bundles up into the end effector 60 and close holding fingers 
120. Then the robot removes the end effector 60 containing the magazine 
bundles and puts these bundles at the designated pocket location on pallet 
90. 
Meanwhile, step 440 updates the actual pocket location height created by 
placement of the most recently placed bundles and calculates a new target 
height for this pocket location. If steps 432 or 434 determine that there 
are no bundles in storage or the robot is not ready, respectively, then 
step 442 decides whether there are any pocket locations left with target 
heights less than the minimum bundle height. If step 442 finds at least 
one pocket location that may accept a bundle then step 446 returns program 
control back to step 410 (FIG. 9). Step 410 starts the accumulation of 
bundles again as described above. 
When step 442 determines that there are no more pocket locations remaining 
in the present layer, then step 444 causes the scissor lift 82 to drop the 
pallet 90 by an amount equal to the present layer height and start 
wrapping the present layer with the stretch wrapper 76. Step 448 
increments all of the pocket location heights both ideal and target. The 
computer program of the present invention tries to make the top terrain of 
the layer as flat as possible for best stacking and shipment stability. In 
doing so, the variations of pocket heights of the lower layers may not be 
precisely the desired height. The program of the present invention 
compensates for the actual height variances by remembering each pocket 
height and using these variances when figuring the pocket height 
calculations for the next layer. 
Step 450 determines whether the pallet 90 loading is complete. If loading 
is not complete then step 450 returns program control to step 408 (FIG. 
8). When the pallet 90 is fully loaded, step 452 causes the system of the 
present invention to final wrap and eject the pallet 90. Step 452 returns 
program control to step 406 (FIG. 8) so that the system of the present 
invention may begin loading a new pallet. 
REMOVAL OF THE LOADED LET AND PLACEMENT OF A NEW LET FOR LOADING 
THEREON 
Referring back to FIGS. 1 and 2, when the pallet 90 is fully loaded the 
scissor lift 82 drops the load station 70 on which the pallet 90 is 
supported to a level even with a powered pallet conveyor 78. Conveyor 78 
may remove the pallet 90 from the load station 70, after which a dispenser 
72 may place a empty pallet onto pallet conveyor 74. Conveyor 74 may place 
the new pallet 90 onto the load station 70. The scissor lift 82 raises the 
new pallet 90 into position for the start of a new loading operation as 
described above. Meanwhile, the pallet conveyor 78 may move the loaded 
pallet to gravity pallet conveyor 80 which may then move the loaded pallet 
to a shipping area. 
ADDITIONAL EMBODIMENTS 
A problem may occur when a bundle is so tall that it cannot be properly 
placed in the existing topology of the present layer being stacked, i.e., 
there are no pocket locations that will accept the height of the new 
bundle. This occurs when a bundle is near the maximum of six or seven 
inches in height. The program of the computer system 94 is such that a 
bundle layer height is obtained by stacking each magazine bundle until a 
certain maximum level is reached. Thus, if only four inches are left to 
complete a stack and a six inch bundle must be placed, then this bundle 
cannot be placed on the stack because it would exceed the maximum height 
of the present layer. 
The system of the present invention may improve the efficiency of the 
stacking operation by leaving one pocket location, toward the middle of 
the pallet, empty until all of the other pocket locations of the present 
layer have been utilized. Another possibility uses a deep hole in the 
middle of the pallet stacks that may be twice as deep as the normal layer 
height. This gives the system of the invention more ways to accept bundles 
of unusual height. 
A holding station 99, illustrated in FIG. 1, may be used for temporarily 
storing a bundle that cannot be readily placed on the present layer. 
Storing a magazine bundle of unusual height in the holding station 99 may 
improve the efficiency of stacking magazine bundles and result in an 
improvement in the layers being level and even. Therefore, the use of a 
holding station 99 and a deep hole in the middle of a stack allows the 
computer system 94 of the invention to more easily and efficiently place 
magazine bundles of unusual heights than would be possible without the 
above methods and apparatus. 
The present invention, therefore, is well adapted to carry out the objects 
and obtain the ends and advantages mentioned as well as others inherent 
therein. While presently preferred embodiments of the invention have been 
given for the purpose of disclosure, numerous changes in the details of 
construction and arrangement of parts will be readily apparent to those 
skilled in the art and which are encompassed within the spirit of the 
invention and the scope of the appended claims.