Note: Descriptions are shown in the official language in which they were submitted.
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Process for Assembly of Corrugated Pallets.
This invention pertains to pallets for shipping goods, and more particularly
to. a
process. for assembly of corrugated, paperboard pallets. that enables. high
volume pallet
5. manufacturing with minimal assembly operator fatigue and with minimized
assembly
machine costs. The process. increases. manufacturing reliability and reduces,
the time
required to, assemble pallets.
Background of the Invention
10. Pallets
are said to. move the world. Eighty percent of commerce ships on pallets.
The pallet industry is. estimated at greater than $30.B. worldwide. More than
500. million
pallets are manufactured in the US each year, with 1.8. billion pallets in
service in the US
= alone.
Pallets can be made from various materials, however wood pallets currently
15 comprise about 80%.of the market. More than 4.0%.of worldwide hardwood
lumber
currently goes toward the manufacturing of wood pallets. Other materials used
for pallet
manufacturing include plastic, metal and corrugated paperboard.
Recent regulations regarding infestation and contamination are creating a
surge in
interest and use of non-_wood pallet alternatives. A small, but fast growing
segment is. the
20. use of corrugated paperboard pallets. Many desire to. replace
conventional wooden pallets
with corrugated pallets: increasing ability to.recycle, lowering pallet
weight, eliminating
product contamination, reducing pallet storage volume and reducing pallet
related injuries.
Many different designs. of corrugated paperboard pallets. have been developed
to.
date. Despite the potential advantages of corrugated pallets, many have
suffered from
25 several different deficiencies. These deficiencies. include low strength
and stiffiless, high
use of corrugated paperboard, resulting in high material costs, along with
high overhead,
assembly labor and freight costs. The inherent inability to.readily produce
and distribute
corrugated pallets in sufficiently high volume has also. been of critical
importance.
Regardless. of the design, it is. desirable to. increase the speed at which
corrugated
3Ø pallets can be produced. Corrugated pallets can be assembled solely by
hand or by
machine. When assembled by hand, the assembly time can be longer than
acceptable for
some high use applications and/or customers. When assembled by machine, the
assembly
speed can be increased, however the assembly machine size and.costs.are
increased and this.
in turn makes the assembly upfront and operating costs to. be higher than
desirable for some
35 customers.and/or parts. of the world. Accordingly, a new corrugated
pallet assembly
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process. is. needed that can be used to. readily produce corrugated, pallets.
in. high volume, at a
high rate and with simultaneous low assembly costs.
Summary of the Invention
=
5. There are currently two. general types of corrugated pallets; one
type comprising
blocks. or runners, of corrugated. board that are stacked, rolled and/or
assembled together and.
then bonded to. top. and bottom decks, and the other type comprising two.
sheets that are
folded and, assembled together to. form. top, bottom and integral vertical
supports. The first
type typically utilizes a high volume of corrugated paperboard and is
expensive. Further
10, compounding the high material. costs. is.the complicated and time
consuming assembly,
which is typically done at an intermediate location, adding more logistical
costs.
The second, general type of corrugated pallet formed from. two. sheets. with
integral
vertical supports between the two. sheets is preferred because of much lower
inherent board
use. Regardless. of the specific design, the assembly is. typically
accomplished in three
15. steps; forming a top, forming a bottom and later assembly of the top.
with the bottom
together. Although less. costly than the first type of corrugated pallets.
because of lower
material costs, manufacturing can be still too. time consuming, involved and
expensive.
A principle goal of the invention is,to.provide a process. for assembly of
corrugated
pallets that enables high volume pallet manufacturing at a high rate with
simultaneous low
20. assembly. costs. We have found. that in. the assembly of corrugated,
pallets, there are
different folding and assembly operations and that some of these operations
are difficult to.
conduct by persons. by hand rapidly and repeatedly. These operations. are
also. easily.
conducted by a machine. We have also. found that some operations in the
assembly of
corrugated pallets.are difficult to. have performed.by machine due to.the
required =
25, mechanical complexity, and resulting reduced reliability and greatly
increased machine
costs. We have found that these operations.that are difficult to.perform. by
machine are also.
surprisingly easy to. be perfonned by persons by hand. This aspect of the
disclosed
preferred embodiments. of invention therefore increases. the assembly rate and
reduces. costs.
associated with corrugated pallet.assembly by utilizing the synergy whereby
pallet assembly
30. is. shared by both use of machine functions.and person hand assembly
functions. For
example, operations that are difficult for persons but easy for a machine can
be completed
by machine, andoperations.that are difficult for a machine but easy by. person
by hand can.
be completed by person by hand. In the assembly process, the assembly
functions can
change back and forth between machine and. person several. times. for optimal
efficiency.
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The process reduces the time required to assemble pallets. and reduces. the
assembly costs,
with minimized assembly operator fatigue and minimized assembly machine
complexity.
It is. an additional goal of the invention to. integrate assembly such that
the process.
can be simplified and steps may be eliminated. For example, in the preferred
embodiments,
the forming of ribs.can be integrated with. the assembly of pallet top.and
bottom together.
Prior art two. piece pallets have ribs or vertical supports that are locked
from opening by
adhesive and/or mechanical locks. self-_contained on, each separate piece. For
instance, in
US Patent 6,029,582 the individual ribs are locked together using jack flaps
and sliding lock
assemblies. US. Patent 7,426,890. teaches. locking of ribs. using folding
flap. lock assemblies,
10. locked prior to. nesting of pallet top. and bottom using a slot and
wing tab. US Patent
7,890,184_teaches. locking support ribs. using a gate flap.and pass.through
aperture. US.
Patent 7,3.03,5.19 further teaches a machine for forming pallet tops and
bottoms wherein the
ribs are locked from opening through the use of adhesive. In each case,
independently
locked ribs provide the benefit of robust ribs that may stay intact even if
pallet becomes
15. partially, disassembled.
The drawback of se1f7.1ocked ribs however is that extra steps and complexity
of the
assembly process.are required. We have found that the assembly of pallet top.
blank nested
with pallet bottom blank can be sufficient to. keep. ribs locked for most
pallet use. Locking
of ribs. from opening in this. way is. achieved by notches. in the top. ribs.
locking the bottom
20. ribs from opening, and notches in the bottom ribs locking the top. ribs
from opening. The
completion of the sides. of the pallet is. utilized.to.hold. the pallet
top.and pallet bottom,
blanks together such that ribs stay locking each other. Added machine
requirements of
maintaining the ribs. of top. and bottom folded under pressure until top.and
bottom are nested
together are desirable. However, the pallet assembly steps and time for
se1f71ocicing of
25 individual ribs.can be eliminated, along with attendant substantial
machine complexity and.
size reduction. The preferred embodiment of the invention provides a
process for
assembling a corrugated pallet using a mix of machine and human performed
operations.
An example of a corrugated pallet that can be assembled with the process of
this invention
includes.tw.o.die cut corrugated paperboard blanks.that form a pallet top.and
a pallet bottom.
3Ø The pallet top. and pallet bottom each have it least one vertically
extending double thickness
rib, and each rib. has. at least one notch, wherein the notches. lock the
opposing ribs. from
opening when the ribs on the pallet top. and the pallet bottom are vertically
nested together.
A machine operating in accordance with this. invention forms, the rib.on each
blank by
applying in-plane pressure to. the blank through protruding elements on the
machine that
35 penetrate the blank or engage the edges. of the blank and. move in
relation towards.each
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other, and the machine maintains. the in-plane pressure to.keep.the rib. from
opening until a
time after the pallet top. and the pallet bottom are nested together. The use
of protruding
elements. or pins. that penetrate the blanks. allows. for sufficiently high in-
plane compression
force for reliable folding of ribs.
It is desirable for the pallet assembly process to occupy the minimal amount
of space
for both reduction of required floor space and. also. reduction of the size
and, cost of the
assembly machine. We have designed the preferred embodiments of the invention
to. allow
the ribs. on the pallet top. and bottom to. be formed while the blanks. are
vertically aligned in
a horizontal position, thereby allowing the pallet top. and bottom to. be
vertically assembled
10. together in the same location. In an additional embodiment of the
invention, the machine
forms the ribs on both the pallet top. and the pallet bottom and nests the
pallet top. and the
pallet bottom together so.that forming and nesting occur without bodily. in-
plane translation
of one or both of the blanks.
For simplicity of the machine design, it is.preferable to.hold.the blanks.
from only
one side instead of two. Holding blanks from both the top. and bottom sides
results in
machine parts.necessarily located betw.een,the tw.o.blanks, significantly
complicating the
assembly and nesting of the pallet top, and pallet bottom in the same
location. Such
machine parts. would. have to be moved or the blanks.moved to.allow nesting of
the pallet
top. and pallet bottom. In a further embodiment of the invention, the machine
utilizes
20. vacuum to hold each blank in a fixed position while protruding
elements. provide in-plane
pressure. In this case, the top. blank is held using vacuum from the top. side
and the bottom
blank is. held using vacuum from. the bottom. side. Pins. though each, blank
move tow.ard
each other to. provide in,plane compression for rib. folding. In7p1ane
pressure is maintained
until after the top. and, bottom are nested together.
25. During the folding of the ribs for the pallet top. and pallet bottom
through application
of in7p1ane compression, there is.a tendency for the ribs.to.fold. in either
the correct
direction or 180. degrees opposite. For instance, ribs from the top. blank
should fold such
that they extend downward while ribs. from. the bottom blank should. fold such
that they fold.
upward. To, assist folding in the desired out7of,p1ane directions, it is
desirable to. apply out
30. of7p1ane force to the ribs. in formation. In an additional. embodiment,
the machine further
comprises rib. folding plates that apply out,of:plane forces to. the blanks
to. assist forming of
the ribs. by rotating in the out-.of7p1ane direction when the in-plane
pressure is.applied.
ofTplane force could be applied by several different means however the use of
rib folding
plates. moving in the out7of7p1ane direction, affords. simple machine
construction. More
35 preferably, the machine further comprises rib. folding plates that apply
out of plane forces to.
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= the blanks. to. assist forming of the ribs. in. the desired. out-
_of7plane directions. by rotating
about a fixed axis in the outTof,plane direction when in7plane compression is
applied.
A drawback to.this.method is. that the folding plates.become trapped. between
the
two. sides of the ribs when folded, once rotated vertically. Surprisingly, we
have found that
this. can be advantageous. in that it can be used to. maintain the ribs. more
accurately vertical.
for easier nesting of the pallet top. and pallet bottom. After the pallet
assembly is
completed, the pallet may be vertically removed, from, the rib. folding
plates. to. remove the
pallet from the machine. In yet an additional embodiment of the 'invention,
the rib. folding
plates, stay inside the ribs. once formed. until. after the pallet top. and.
the pallet bottom are
10. nested together.
The assembly process. of maintaining in-plane pressure to.keep.the ribs. from,
opening against board memory until after the top. and bottom are nested
eliminates the need
for self contained rib. locks. or the use of adhesives. Adhesives. add
significant costs. and.
machine complexity as well as reduce machine reliability. Adhesives alsc.
require time to.
15. set.
Likewise, integral mechanical, rib. locks. on. each. blank would. require
machinery to. =
engage inside the space between both the pallet top. and pallet bottom,
hindering nesting of
the pallet top.and, bottom together at the same location. In a further
embodiment, the
assembly process utilizes no. integral corrugated mechanical or adhesive
locking of the ribs
from opening prior to. said. nesting.
20. The process for assembling the corrugated pallet can be completed with
both
persons, and machine for minimized, assembly. cost and. assembly. ease. Some
tasks. are best
done by machine and other best done by person. Forming of ribs and nesting of
the top. and
bottom. together are best done by machine. Loading blanks. and. folding
sidewalls. is. in, many.
cases best done by person, since they are easy hand operations that are more
difficult to.
25. automate. In an additional, embodiment of the invention, at least one
person loads. the
blanks into. the machine, the machine forms the ribs, the machine nests the
pallet top. and the .
pallet bottom together, and, at least one persons. folds. the sidew.alls. of
the pallet in the out-._
ofTlane direction.
The size of the machine for use with the disclosed, assembly process. is.
minimized.
3Ø through the use of rib. folding that occurs with the blanks static. The
process is more
complicated than conventional corrugated. folding performed by. bodily moving
blanks. over
fixed mandrels, for example on a conveyor belt, and is potentially slower. In
a further
embodiment, the machine forms.the ribs.on. the blanks. while bodily,
translationally static,
and nests the pallet top. and the pallet bottom together by both rotating the
pallet top. and /or
35 the pallet bottom so. the top. and. bottom, ribs. are perpendicular to.
each. other, and. by moving
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the pallet top and/or the pallet bottom towards.each other in the out-.of-
.plane direction. Of
course, the top. and bottom blanks have portions that move in the in7plane
direction
inwardly during rib. formation, but otherwise the blanks. remain, bodily
static against in.
plane translation.
Description of the Drawings
The invention and its.many advantages:and features.will become better
understood
upon reading the following detailed description of the preferred embodiments
in
conjunction with the following drawings, wherein:
10. Fig. 1 is a flow diagram of a process for assembly of corrugated
pallets in
accordance. with the invention.
Fig. 2 is a plan view of a set up. to. execute the process of Fig.1 for
assembly of
corrugated pallets. in, accordance with the invention.
Fig. 3. is a schematic side elevation of a pallet assembly machine of Fig. 2.
Fig. 4_ is. a perspective drawing of a corrugated pallet assembled in
accordance with
the invention.
Fig. 5 is an exploded perspective drawing of a corrugated pallet in flat blank
state to.
be assembled into a the pallet of Fig. 4.
Fig. 6 is. an exploded perspective view of corrugated pallet blanks. shown in
Fig.
20. 5,with opposing ribs folded in accordance with the invention.
Fig. 7 is. a perspective drawing of topand. bottom blanks.of the corrugated
pallet
shown in Fig. 4, with ribs nested together in accordance with the invention.
Fig. 8. is, a schematic drawing of the corrugated pallet shown in Fig. 7,w.ith
sidewalls.
tucked in accordance with the invention.
Fig. 9, is_ a perspective view of corrugated.pallet shown in Fig. 8,with fork
windows.
opened in accordance with the invention.
Fig. 10A is. a schematic drawing of a configuration of a folding section of
another
embodiment of a pallet assembly machine . prior to. folding ribs.
Fig. 10B. is.a schematic drawing of a configuration of the folding section of
the
pallet assembly machine of Fig.10A. after folding ribs.
Description of the Preferred Embodiment
Turning to. the drawings, wherein like reference characters designate
identical or
corresponding parts, and more particularly to:Figs.1-3. thereof, Fig. 1
shows.a preferred
35. embodiment of a process for assembly of corrugated pallets in
accordance with the
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invention. The process. 30 comprises, step 31: loading blanks_101,102 into.the
pallet
assembly machine 60. by hand. In one embodiment, illustrated in Fig. 2, one
person
(represented, by icon 53). loads. top blanks. and. another person
(represented. by icon. 54). loads.
bottom blanks from opposite sides of the machine. Loading blanks from uneven
and
5. misaligned. stacks, of blanks. is, very easy by humans. but difficult by
machine. After the
blanks are loaded, the next step. 32 is folding ribs on top. and bottom
blanks, 10.1, 102, which
is preferably done by machine because it is. difficult to.do.as, quickly by.
hand, since each
blank needs to, be gripped or held at several places at the same time. The
third step. 33 is to
rotate the top.blank to.bottom blanks.by 90.degrees.suchthat they can. be
assembled
10. together perpendicularly. This step. is easily conducted by machine.
After rotation, the
fourth step.34_ is_ to. compress. the top. to. bottom, blanks. 10.1, 102
together. Because the
compression can take over 10Ø1bs of force to. assemble the top. to. bottom,
fully nesting the
ribs. of each, together, this. is, best accomplished. by machine. The fifth
step.35. is. to. fold. up,
= and tuck in sides 1 and 3, which is difficult to. do. by machine due to
motion complexity and
15. required. accuracy, but easy by a person due to. low force required.
The sixth. step,36.is.to,
open the fork windows of side 1 and 3, which is easily done by a person. The
seventh step.
3.7..is_to rotate the top. and bottom together by 90.degrees.so.that the
sides.2 and, 4.can.be
completed. This step. is easily accomplished by machine. The eighth step. 3.8.
is to. fold up.
and tuck in sides,2 and 4, again. preferably done by. a. person. The ninth
step. 39. is. to.
20 the fork windows in sides 2 and. 4, which is easily done by hand where a
machine would
require significant mechanical. complexity. The last step.in.the
process.30.is.the locking of
the corner straps 4Ø This operation could be done by machine or by person
relatively
easily.
A plan view of a set up. to execute the process, of Fig.1 for assembly of
corrugated
25. pallets_ in accordance with the invention is: shown, in, Fig. 2. The
set up.50.comprises,a stack
5.1of top. blanks 101, a stack 52 of bottom blanks 102and two. human operators
53, 54. The
operators. 53, 54_ load. blanks.10.1, 102 into.the pallet assembly. machine
60. The machine 60.
comprises a vertical beam support 6.1 and a top. cantilever support 62. The
top. blanks are
=
loaded into.the top.frame 63. The assembly. process.may. alternatively be
accomplished by.
3Ø putting both sets of blanks 5.1, 52 on the same side of the assembly
machine and then a
single operator 53. loading both. blanks.one after the other.
A side elevation of the pallet assembly machine 60. shown in Fig. 2 for
assembling
corrugated, pallets. in, accordance with the invention. is, shown. in Fig. 3.
The assembly.
machine is preferably powered by pneumatic cylinders, which are omitted from
the drawing
35. for simplicity and clarity of the overall, machine functioning. The
machine preferably.
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= operates with sensors that sense when the top. and bottom blanks 10.1,
102 have been loaded.
The sensors, not shown, trigger the start of the rib forming timing sequence,
which is
preferably operated by a programmable logic controller. The sensors may be
blank sensors
or alternatively foot switches that are triggered by an assembly operator.
The machine 60. comprises a vertical beam support 6.1, a top. cantilever
support 62
and a bottom support 67. A top frame 63 is supported below the top cantilever
support 62
by a bearing 64. to. allow for rotation of the pallet top. Mounted on the top
frame 63. is a
slide support 65, supporting three rows of vacuum cups 66 that are used to
grip the top
blank 10.1, slide together while two. parallel ribs are formed in the top.
blank 10.1. When the
vacuum cups 66 suck the top blank 101 up against stops, the elements 74.
engage the top
blank 10.1 at the edges to. apply in-plane pressure to. fold the ribs as the
vacuum cups 66
slide inward to hold portions of the top blank in-plane as they move inward
toward each
other,
The bottom frame 68 is supported above the bottom support 67 through a lift
linkage
15. 72 and a bottom bearing 69. Mounted on the bottom frame 68 is a slide
support 70,
supporting three rows of vacuum cups 71 that are used to grip the bottom blank
102, slide
together and form two. parallel ribs of the bottom blank 102. When the vacuum
cups 71
suck the bottom blank 102 down against stops, the elements 75 engage the
bottom blank at
the edges to. apply in,plane pressure for folding the ribs, while the vacuum
cups 71 hold
portions of the top blank implane as they move inward toward each other while
the ribs are
formed. . After the top. and bottom blanks 10.1, 102 have ribs formed and are
vertically
compressed together by the lift linkage 72, and sidewalls are hand assembled,
the corner
straps of the pallet are assembled by arms 73 on the assembly machine 60. The
corner
straps may alternatively be assembled by person by hand.
25. A perspective view of a corrugated pallet 100. assembled in accordance
with the
invention is shown in Fig. 4. The pallet 100is constructed from two sheets of
corrugated
paperboard comprising the pallet top. and pallet bottom that are folded
together. We have in
mind other configurations of corrugated pallet that could also be assembled in
accordance
with the invention. The pallet 100. can have either four way entry holes or
two. way entry
holes for forks or pallet jacks used to move the pallet.
The corrugated pallet 100. shown in Fig. 4. is shown in Fig. 5. in flat blank
state. The
pallet 100 is comprised of a top blank 101 and a bottom blank 102. The blanks
101, 102 are
die cut for easy and accurate folding to. make the finished pallet. The die
that cuts the
blanks 101, 102 installs cuts and also scores into the blanks.
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In Fig. 6, the pallet 100 shown in Figs. 4 and 5 gains internal vertical
support
structure by vertical ribs 103 ,104 being folded into the pallet top and
bottom 101, 102.
Notches 110 in the bottom ribs 104 lock the top ribs 103 from opening when the
pallet top
101 is vertically nested together with the pallet bottom 102. Likewise,
notches, not shown,
in the ribs of the pallet top 101 lock the bottom ribs 104 from opening when
pallet top 101
and pallet bottom 102 are vertically nested together.
In Fig. 7, the pallet top 101 and bottom 102 have been rotated 90 degrees, as
shown
in Fig. 6, and compressed together. Notches in the ribs 103 intersect and lock
perpendicularly into corresponding notches110 in ribs 104. This provides cross
support for
the pallet 100 and also utilizes each set of ribs 103, 104 to lock each other
from opening.
The corrugated pallet 100 shown in assembly in Figs. 5-7 is shown in Fig.
8with
sidewalls tucked in accordance with the invention. After the top and bottom
blanks 101,
102 are compressed together, a person or persons preferably completes the
sidewalls 105,
106 of the pallet by tucking them in. This operation forms the sidewalls 105
from the pallet
top 101 and the sidewalls 106 from the pallet bottom.
The corrugated pallet 100 shown in assembly in Figs. 5-8 is shown in Fig. 9
with
fork windows opened in accordance with the invention. After sidewalls 105, 106
have been
tucked in (steps 35 and 38), the next operation (step 39) is to open the fork
windows in the
pallet 100. The pallet top 101 forms sidewalls 105 and cuts and scores in the
blank provide
for fork openings 107. The pallet bottom 102 forms sidewalls 106 and cuts and
scores in
the blank provide for fork openings 108. The openings 108 are opened simply by
pushing
the blank sidewalls in where the blanks have been pre-cut to allow the
paperboard to swing
in. The last step is locking the comer locks 109 that extend from the top
blank 101 and
overlap and enter in the bottom of the bottom blank 102. The corner locks
shown on the
bottom blank 102 are not used in this embodiment to maintain a smooth top for
the pallet
100.
A schematic drawing of a configuration of the folding section of the pallet
assembly
machine of Fig.3. is shown in Fig. 10A, prior to folding ribs. The folding
section 120 folds
vertically, folding double thickness ribs 131, 132 into bottom blank 102.
Prior to folding
ribs, the blank 102 is flat. The blank 102 is placed onto the folding section
120 by setting
the blank over protrusions 125, 126 on the sliding portions 122, 123 that
penetrate the
blank. A benefit of using pins 125, 126 that penetrate the blank 102 is that
the pins can be
used to accurately position the blanks into the machine as well as provide
high in-plane
pressure for rib folding. Sliding elements 122, 123 and center portion 124
have vacuum
cups 71 that suck the blank 102 down. After penetrating the blank 102,
protrusions or pins
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125, 126 apply in-plane compression to the blank through bearing force as
sliding sections
122, 123 are forced inward toward the center element 124. The blank 102
preferably
comprises scores 121 that bend and facilitate upward folding of the ribs 131,
132, out of
plane, as shown in Fig. 10B. Rib folding plates 127, 128 supported by rotary
bearings 129,
130 contact the blank 102 near the center scores 121 that later form the rib
top of both ribs,
to initiate rib folding of. As in-plane compression is applied, suction cups
hold the non-
folding portions of the blank 102 in-plane while the the rib folding plates
127, 128 rotate
vertically, applying out-of-plane force to the blank causing the ribs to fold
in the desired
direction.
A schematic drawing of a configuration of the folding section of the pallet
assembly
machine of Fig.3. after folding ribs is shown in Fig. 10 B. The sliding
portions 122, 123
have slid inward toward the center portion 214 and rib folding plates 127, 128
have rotated
vertically forming ribs 131, 132. The rib folding plates 127, 128 are trapped
inside the
double thickness ribs 131, 132 and hold them to be accurately vertical,
allowing top and
bottom blanks to later be easily assembled together. Upon completion of the
pallet, vacuum
is removed from vacuum cups 71 and the pallet is vertically slid off of the
rib folding plates
131, 132 and protrusions 125, 126 prior to rotating rib folding plates open
and sliding of
sliding portions outward.
Obviously, numerous modifications and variations of the described preferred
embodiment are possible and will occur to those skilled in the art in light of
this disclosure
of the invention. Accordingly, I intend that these modifications and
variations, and the
equivalents thereof, be included within the spirit and scope of the invention
as defined in the
following claims, wherein I claim:
