U.S. patent number 3,833,132 [Application Number 05/245,842] was granted by the patent office on 1974-09-03 for pallet loading apparatus.
Invention is credited to Frank P. Alduk.
United States Patent |
3,833,132 |
Alduk |
September 3, 1974 |
PALLET LOADING APPARATUS
Abstract
An apparatus for loading objects on a pallet has a cross frame
movable vertically between upright supports. There is a shuttle
table over the cross frame movably carried on it for travel from a
load-receiving position at one end of the frame to a load-discharge
position at the other end with means for traversing it back and
forth. A restraining bar movable from a position where it is clear
of the load when the table moves forward to a position over the
pallet, but which obstructs the load as the shuttle table moves
back, causes the load to be forced off the table onto the pallet or
partially-formed load already on the pallet. One layer is deposited
on the load with each forward and back cycle of the shuttle table.
When the load is complete the cross frame is raised to a level
above the load to clear the loaded pallet which is then removed,
but at all other times the cross frame surrounds the load at or
near its top to guard against accidental toppling of the load. An
improved restraining bar is on dead center when it is in
loadrestraining position with the pivotal axis about which it moves
between load-restraining and load-clearing position so that the
back thrust of the load against the bar is not transmitted to the
bar-moving mechanism.
Inventors: |
Alduk; Frank P. (New Castle,
PA) |
Family
ID: |
26937506 |
Appl.
No.: |
05/245,842 |
Filed: |
April 20, 1972 |
Related U.S. Patent Documents
|
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
|
854930 |
Sep 3, 1969 |
|
|
|
|
Current U.S.
Class: |
414/793.8;
414/794.3; 414/900 |
Current CPC
Class: |
B65G
57/005 (20130101); B65G 57/18 (20130101); B65G
57/24 (20130101); B65G 57/14 (20130101); B65G
57/112 (20130101); Y10S 414/114 (20130101) |
Current International
Class: |
B65G
57/00 (20060101); B65G 57/02 (20060101); B65G
57/24 (20060101); B65g 057/22 () |
Field of
Search: |
;214/6DK,6H,6P,6G,6M,6N,8.5SS,8.5A ;198/35 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Spar; Robert J.
Attorney, Agent or Firm: Parmelee, Miller, Welsh &
Kratz
Parent Case Text
This invention is for an apparatus for arranging and placing
objects on pallets for transportation or storage, and this
application is a continuation-in-part of my application Ser. No.
854,930 filed on Sept. 3, 1969, now abandoned.
Claims
I claim:
1. Apparatus for stacking articles on pallets which comprises:
a. a base structure with a pair of spaced parallel upright columns
thereon and having a pallet support at one side of the columns on
which a pallet is placed for loading,
b. an elongate frame supported between its ends for movement
upwardly and downwardly on said columns, the elongate frame having
a loading end and an unloading end at opposite sides of said
columns, the unloading end being positioned over said pallet
support, the elongate frame having side frame members spaced to
clear the two opposite sides of a load being stacked on a pallet
placed on said support, and cross members connecting the side frame
members and spaced to clear the other two sides of the load being
so stacked, the side frame members and cross frame members defining
an opening at the unloading end of the cross frame so arranged that
the side members and cross members may surround the uppermost
portion of a stack being arranged on a pallet, the pallet support
being centered under said opening,
c. a load-transferring shuttle table above and supported on said
elongate frame and movable back and forth over the elongate frame
between a retracted load-receiving position at the loading end of
said frame and an extended position over the unloading end of said
frame,
d. a load-restraining means supported on the elongate frame
intermediate its ends movable between a raised position over said
elongate frame where it is clear of any load being carried on the
shuttle table from the receiving end of the elongate frame toward
its extended position and a lowered position where it restrains
movement of a load on the shuttle table when said shuttle table is
moved from the extended position over said elongate frame to the
retracted position,
e. means for controllably raising and lowering the elongate
horizontal frame,
f. means for controllably moving the shuttle table back and forth
on said elongate frame,
g. means for controllably moving the restraining means between its
raised position and its lowered position, and
h. stack-supporting means on the frame movable in the area of said
opening to engage the uppermost portion of the stack being formed
on the pallet and brace it when the shuttle table is moving from
its extended position back from the unloading end of the frame
toward the loading end.
2. Apparatus for stacking articles on pallets as defined in claim 1
wherein the said opening at the unloading end of the elongate frame
at its lowermost limit of travel on said columns is arranged to
surround a pallet which is placed on said pallet support and the
shuttle table is then at a level where it may move over and clear
the top of a pallet so positioned, said means for controlling the
raising and lowering of the elongate frame comprising:
a. a reversible electric motor and means driven thereby for raising
and lowering the elongate frame,
b. a flag switch arranged to stop said motor whether the frame is
moving up or down at a home position intermediate the lowermost and
uppermost limits of travel of the frame at a level convenient for
arranging a load on the shuttle table, and
c. control switches for selectively moving the elongate frame
downwardly or upwardly from said home position.
3. Apparatus for loading articles on pallets as defined in claim 1
wherein said stack-supporting means on the frame movable in the
area of the opening is a load-engaging member reciprocable in the
direction of the length of the elongate frame at a level to engage
the uppermost tier of articles on the stack across substantially
the entire width of the stack, and means for moving said member
toward the stack when the shuttle table is about to place
additional articles on the stack and retract it after said
additional articles have been placed on the stack.
4. Apparatus for loading articles on pallets as defined in claim 3
in which there is a second such supporting member on the elongate
frame opposite the first in a position to move into and out of
position to confine the articles on the top tier at the side of the
load opposite the side which is contacted by said first member, and
means for moving the second member into and out of article-engaging
position simultaneously with the first.
5. Apparatus for loading articles on pallets as defined in claim 4
in which fluid pressure cylinders operate said two members in
unison.
6. Apparatus for loading articles on pallets as defined in claim 4
in which there are two other such supporting members on the
elongate frame for engaging the said top tier of articles on the
two sides at right angles to said first two members and similarly
movable toward and away from the top tier but at right angles to
the direction of movement of said first and second support
members.
7. Apparatus for stacking articles on pallets which comprises:
a. a base structure with a pair of spaced parallel upright columns
thereon,
b. an elongate frame supported between its ends for movement
upwardly and downwardly on said columns, one end of the elongate
frame at one side of the columns being a loading end and the other
end at the other side of the columns is an unloading end,
c. a load-transferring shuttle table above and supported on said
elongate frame and movable back and forth over the elongate frame
between a retracted load-receiving position at the loading end of
said frame and an extended position over the unloading end of said
frame,
d. a load-restraining means supported on the elongate frame
intermediate its ends movable between a raised position over said
elongate frame where it is clear of any load being carried on the
shuttle table from the loading end of the elongate frame toward its
extended position at the unloading end and a lowered position where
it restrains movement of a load on the shuttle table when said
shuttle table is moved in the reverse direction,
e. means for controllably raising and lowering the elongate
horizontal frame,
f. means for controllably moving the shuttle table back and forth
on said elongate frame,
g. means for controllably moving the restraining means between its
raised position and its lowered position,
h. the upright columns being structural sections having a web with
confronting spaced parallel flanges, said elongate frame having an
upwardly-extending side plate at each side thereof along the outer
face of which is mounted a vertical series of at least three
rollers spaced one above another and adjustable horizontally with
respect to one another, the rollers being so arranged that the
upper and lower ones roll against one of said side flanges of a
column and the intermediate one rolls against the other side flange
whereby the elongate frame is held against tipping in either
direction from a horizontal position but is easily movable up and
down along said columns,
i. the sideplates having chains attached thereto through which
raising and lowering thereof is effected, wherein said restraining
means comprises two levers, each one pivotally mounted on one end
to one said side plates, a restraining bar connecting the free ends
of said levers, the levers being movable in a vertical arc from a
position above the plane of movement of the shuttle table
downwardly to a level where the restraining bar will contact
articles on the shuttle table to restrain them from movement with
the shuttle table, the arrangement being such that the restraining
bar is on a horizontal dead center with the pivotal mountings of
said levers on their respective side plates when the bar is in
load-restraining position, there being a fluid pressure cylinder
and piston on each said side plate for moving the respective levers
simultaneously, said cylinders and pistons being arranged with
respect to said levers that the piston of each is fully retracted
into its cylinder when the restraining bar is in load-restraining
position so that the piston cannot retract further when pressure is
exerted against the restraining bar.
8. Apparatus for stacking articles on a pallet as defined in claim
7 wherein each of said levers is a toggle lever with first and
second sections pivotally joined to each other and with one end of
the first section being pivotally mounted on the side plate, the
ends of the second sections of the two toggle levers being
connected by a restraining bar extending transversely across the
plane of travel of the shuttle table, said toggle levers each being
straight from end to end when the restraining bar is in
load-restraining position and the pivotal mountings for the
respective toggle levers and the pivotal joint between the first
and second sections of each is on dead center, the second section
of each toggle lever being free to swing in an arc downwardly
relative to the first section through a limited arc less than
90.degree. when the toggle levers are raised to move the
restraining bar to its load-clearing position, and means for
preventing said levers from swinging downwardly past said dead
center position.
9. Apparatus for stacking articles on pallets as defined in claim 8
in which the pivotal mounting for said levers are arranged to be
adjustably fixed on the side plates to be raised and lowered to
adjust the height of said levers and the restraining bar relative
to the shuttle table, and means for correspondingly adjusting the
position of the respective fluid pressure cylinder and piston units
as the pivotal mounting for the levers is adjusted.
10. Apparatus for stacking articles on pallets as defined in claim
7 in which the restraining bar is adjustable lengthwise along said
levers to vary the position at which the restraining bars will be
effective to begin removal of a load from the shuttle table when
said table retracts.
11. Apparatus for stacking articles on pallets which comprises:
a. a base structure with a pair of spaced parallel upright columns
thereon,
b. an elongate frame supported between its ends for movement
upwardly and downwardly on said columns, and having a loading end
and an unloading end,
c. a load-transferring shuttle table above and supported on said
elongate frame and movable back and forth over the elongate frame
between a retracted load-receiving position at the loading end of
said frame and an extended position over the unloading end of said
frame,
d. a load-restraining means supported on the elongate frame
intermediate its ends movable btween a raised position over said
elongate frame where it is clera of any load being carried on the
shuttle table from the receiving end of the elongate frame toward
its extended position and a lowered position where it restrains
movement of a load on the shuttle table when said shuttle table is
moved from the extended position over said elongate frame to the
retracted position,
e. means for controllably raising and lowering the elongate
horizontal frame,
f. means for controllably moving the shuttle table back and forth
on said elongate frame,
g. means for controllably moving the restraining means between its
raised position and its lowered position, and
h. a reversible friction drive for moving the shuttle table back
and forth over the elongate frame and control circuits for
effecting operation of said reversible friction drive at any level
of the elongate frame between the lowest and highest positions
thereof.
12. Apparatus for stacking articles on pallets as defined in claim
11 wherein there is an electric eye system arranged to stop the
upward travel of the elongate frame when said frame is above the
home position and is at a level where the shuttle table may move
from the retracted position to its extended position and just clear
the uppermost layer of articles on the pallet being loaded.
13. Apparatus for stacking articles such as cartons with
partially-open flaps on pallets as defined in claim 12 wherein said
electric eye system after stopping the upward travel of the
elongate frame comprises means for effecting the operation of said
friction drive to move the shuttle table to its extended position
and means to effect limited downward travel of the elongate
cross-frame with the shuttle table in such position, means for
selectively positioning pegs at spaced intervals along the side of
one of said upright columns, and means on said elongate frame
arranged to engage one of said pegs when the elongate frame is then
moving down to stop such downward travel when the partially-open
flaps of the cartons of the last deposited layer have been closed
by contact with the underside of said shuttle table in its extended
position as the frame is lowered.
14. Apparatus for loading articles on pallets one layer at a time
as defined in claim 11 wherein said means for controllably moving
the shuttle table back and forth over the elongate frame comprises
a friction wheel on the elongate frame bearing against the
underside of the shuttle table and a reversible electric motor for
driving said friction wheel.
15. Apparatus for loading articles on pallets as defined in claim
14 wherein the friction wheel is resiliently urged against the
underside of the shuttle table.
16. Pallet loading apparatus and the like comprising:
a. a vertical frame with spaced upright columns,
b. an elongated cross-frame between the upright columns and
supported for up-and-down movement in the columns,
c. the cross-frame comprising parallel spaced beams and having a
rear end portion and a forward end portion, the space between the
beams at the forward end portion providing an open area, the beams
at each side of the frame having rollers at spaced intervals
therealong,
d. a shuttle table suported on said rollers for back and forth
movement along the cross-frame on said rollers between a retracted
position over the rear end of the cross-frame to an extended
position over said open area at the forward end of the
cross-frame,
e. a restraining bar supported on the cross-frame intermediate the
forward and rear end portions movable between an elevated position
above the shuttle table to a load-obstructing position close to the
top surface of the shuttle table,
f. means for raising and lowering the cross-frame,
g. means for moving the shuttle table between the retracted and
extended positions,
h. means for moving the restraining bar between the elevated and
load-obstructing positions,
i. a pallet-supporting means under the open space between the beams
at the forward end of the cross-frame on which a pallet to be
loaded may be removably centered, the open space between said beams
at the forward end of the transverse frame being longer and wider
than a pallet which said pallet-supporting means is designed to
receive, whereby a load may be placed in successive layers on the
pallet so placed with the beams of the cross-frame being below the
top of a previously-deposited layer, and
j. a friction drive for effecting back-and-forth movement of the
shuttle table.
17. Pallet loading apparatus as defined in claim 16 wherein there
is a support resiliently suspended from the cross-frame at a
location beneath the forward end of the shuttle table when it is in
retracted position and under the rear portion of the shuttle table
when it is in its extended position, at least one friction wheel
mounted on said support with its periphery resiliently urged
against the under surface of the supporting table, and a reversible
motor for driving the friction wheel to provide the friction drive
for effecting the back-and-forth movement of the table.
18. Pallet loading apparatus as defined in claim 16 wherein said
pallet support comprises a roller table which in turn comprises
parallel roller conveyor sections and a supporting frame to which
said sections are affixed, said supporting frame being removably
set in the base and of such dimension that the conveyors may be
selectively set crosswise or lengthwise with respect to the
longitudinal axis of the vertically-movable cross-frame.
19. Pallet loading apparatus as defined in claim 16 in which said
friction drive is a motor-driven friction wheel on the cross-frame
resiliently bearing against the underside of the shuttle table, the
shuttle table being free to lift vertically should the shuttle
table strike the top of a load by accidental lowering of the
cross-frame when the shuttle table is over the open forward end of
the cross-frame and it strikes the load in position on the
pallet.
20. Pallet loading apparatus as defined in claim 17 wherein there
are switch means on the forward end of the shuttle car to stop its
driving means if the shuttle table moves forward against the load
being placed on a pallet and also for stopping the means for
lowering the cross-frame if the cross-frame lowers to bring the
shuttle table into contact with a load already in position on the
pallet.
Description
BACKGROUND OF THE INVENTION
The stacking of various packages, cases, cartons, blocks and divers
other objects on pallets for handling, storage and shipment is now
extensively practiced, but in most instances the articles must be
loaded onto the pallets and put in place, one at a time. Starting
with a pallet at ground level, labor receives the articles from a
conveyor or in some other manner where they are lifted individually
and placed on the pallet in a prearranged pattern. At first the
laborer must bend over to place the first one or two layers, but as
the load builds up, he must lift the articles higher and higher,
often to levels above his shoulders. In many cases the objects are
heavy, such as cases of canned products, paint or solid articles
such as building blocks, and in any event the work is tiring and
may cause physical injury.
Attempts have been made to lighten this work, as by having an
elevated work floor or platform with a pallet support that is
lowered as the load on the pallet builds up, with the loaded pallet
being removed at a lower floor, but this has many drawbacks, not
the least of which is the fact that it is not feasible to provide
the required ceiling height, or because of other limiting
conditions in many plants, while another difficulty arises from the
fact that the pallet supporting and lowering device must be heavy
enough to accept the increasingly heavy load until the full load is
placed on the pallet. There are other objections which need not be
here explained. British patent 964,411 cited as a reference against
the parent application of which this is a continuation-in-part
discloses an apparatus designed to perform much the same function
as that of the present invention but has certain drawbacks which
will become more apparent as the description of my invention
proceeds.
SUMMARY OF THE PRESENT INVENTION
The present invention provides a unique pallet loading structure
comprising essentially a base having a palletreceiving roller table
thereon almost at floor level onto which a pallet may be placed,
and from which the loaded pallet may be easily pushed to a position
where the loaded pallet may be engaged by a fork lift truck, or
otherwise removed.
This base provides a support for an upright frame comprised of two
spaced parallel structural columns, one at each side of the base.
They are joined by a cross structure at the top. These columns
provide a guideway for a verticallymovable horizontal cross frame
comprised principally of two spaced horizontal beams carried on
trolleys that ride on the uprights, and these beams are attached to
the trolleys about midway between their ends so they extend through
the upright frame and project outwardly at each side of the
uprights. They are spaced from each other a distance such that they
may straddle the pallet on the roller table when the cross frame is
at its lowest position, and straddle the load on the pallet as it
is progressively built up, never leaving a position where they
support the load against being toppled after the first few layers
have been put in position until the load is completed. These beams
extend a distance such that their ends are beyond the most remote
edge of the pallet at one side of the upright frame. The beams at
the other side of the frame extend outwardly beyond the upright
frame about the same, or a slightly greater distance. A
motor-driven mechanism raises or lowers the cross frame from a
convenient "home" or starting level under the control of an
operator.
Above the cross frame and supported on it for back and forth travel
is a shuttle table that is moved between a retracted position at
one side of the vertical frame to an extended position at the other
side of the vertical frame where it is then positioned over the
pallet-receiving roller table on the base below it. With the
shuttle table in the retracted position and the cross frame at the
home or loading level, the operator places the objects in a layer
of the desired pattern on the shuttle table which is accessible on
three sides for receiving and arranging the load. The cross frame
is then lowered or raised, depending on the extent to which the
pallet has been loaded, to a level just above the level at which
the objects are to be laid, and then the shuttle table is moved
back while a restraining bar, forming part of the cross frame
assembly, moves into position behind the layer of objects to keep
them from riding back with the shuttle table, so that the objects
drop onto the pallet, or the previously-formed load on the pallet,
as the shuttle table moves back.
Since the cross frame always returns to its home position for
loading, this position is arranged to be of a convenient height for
the operator in order to avoid a minimum of lifting, stretching, or
bending. The weight of the load on the pallet is always on the
fixed roller table, and not on an elevator or movable platform, and
provision of an elevated floor for loading is unnecessary.
A primary object of the invention is to provide a pallet loading
apparatus of unique construction designed to reduce the manual
labor generally required for this work, and which ordinarily is
useful in commercial buildings without alterations of the building
or the construction of elevated platforms.
A further important object is to provide a machine for this purpose
which will adapt itself to various arrangements of floor space in
different plants where it is used.
A still further object is to provide a machine for loading pallets
which is relatively simple and inexpensive compared with machines
heretofore provided for this purpose, and which embodies safety
features designed to protect the operator and the load against
error in its operation.
These and other objects and advantages are secured by my invention
as will be understood by those skilled in the art in the light of
the following detailed description thereof in conjunction with the
accompanying drawings showing a present preferred embodiment of the
invention. In the drawings:
FIGS. 1 to 4 are more or less schematic longitudinal sections
through the machine showing various operating conditions;
FIG. 5 is a side elevation of the apparatus;
FIG. 6 is a top plan view of the apparatus shown in FIG. 5;
FIG. 7 is a horizontal section in the plane of line VII--VII of
FIG. 5 showing the base structure and roller table, other parts of
the machine not being shown;
FIG. 8 is a detail longitudinal section in the plane of line
VIII--VIII of FIG. 7, part of the base structure being broken away
and showing a pallet in place with a partial load on the roller
table;
FIG. 9 is a front elevation of the machine looking from the
load-receiving end;
FIG. 10 is a side elevation on a larger scale of one of the columns
of the vertical frame, the view here shown being the right-hand
column as viewed in FIG. 9, the upper part of the column being
broken away;
FIG. 11 is a longitudinal vertical section through the machine in
the plane of line XI--XI of FIG. 6 with the top portion of the
vertical frame being omitted;
FIG. 12 is a transverse vertical section in the plane of line
XII--XII of FIG. 11;
FIG. 13 is a horizontal section in approximately the plane of line
XIII--XIII of FIG. 9, but on a larger scale, and showing the
shuttle table retracted with the previously-established load on the
pallet, and showing electric eye controls;
FIG. 14 is a fragmentary section in the plane of line XIV--XIV of
FIG. 12;
FIG. 15 is a detail front elevation of one of the guide roller
mountings shown in FIG. 14;
FIG. 16 is a simplified basic control circuit diagram;
FIG. 17 is a fragmentary side elevation of the inside face of one
of the side plates of the vertically movable frame showing a
modified restraining bar arrangement with the bar in its uppermost
position, the view actually being a section along the center-line
of the apparatus;
FIG. 18 is a similar view with the restraining bar in operative
position;
FIGS. 19 and 20 are fragmentary enlarged detail views of the hinged
side arms on which the restraining bar is carried, FIG. 19 being a
top view and FIG. 20 a side view;
FIG. 21 is a transverse section through one of the upright columns
26, with a modified control arrangement fixed thereto;
FIG. 22 is a side elevation of the column of FIG. 1 with the
attached parts, showing one of the side frame members 40 to
indicate the cross frame and shuttle;
FIG. 23 is a fragmentary view at right angles to FIG. 22; and
FIG. 24 is a block type circuit diagram of a portion of the circuit
to which the parts shown in FIGS. 21 to 23 relate.
The invention may perhaps be best understood by a general
description of the basic parts of the machine and brief reference
to the operation followed by a more detailed description of the
several parts. To this end, reference will first be made to FIGS. 1
to 4, wherein 2 designates generally a structural base frame to
which is secured a fixed upright frame designated generally as 3. A
roller table 4 is set in the base frame at one side of the upright
frame. There is a vertically movable horizontal cross frame,
designated generally as 5, and it is mounted for vertical movement
in the upright frame. It extends through the upright frame with one
end extending to the left (as here shown) above and beyond the
roller table 4, and the other end extends to the right of the
upright frame a slightly greater distance. Movable horizontally
above and supported on the cross frame is a shuttle table 6. There
is a restraining bar and its operating mechanism designated
generally at 7 mounted in the cross frame movable in an arc from an
elevated load-clearing position shown in FIGS. 1, 2 and 3 to the
load-engaging and restraining position in FIG. 4. A pallet P is
shown in place on the roller table, and C represents a conveyor or
other means on which the objects, O, to be loaded, are brought to
the loading apparatus at a convenient height above the floor.
The schematic views 1 to 4 show graphically the general operation.
In FIG. 1 the dotted line position shows the normal "home" or
loading level of the cross frame, at which level the objects are
moved without lifting from the conveyor C and where they are
manually arranged more or less according to pattern on the shuttle
table 6. The pallet in FIG. 1 has no previously-deposited load, so,
under the control of the operator, the cross frame 5 is dropped to
its lowest level where the shuttle table is in a plane just about
an inch or so above the top of the pallet.
FIG. 2 is about the same as FIG. 1 but shows in broken lines three
layers of objects already on the pallet, and the cross frame is
just about at the home level. When the load on the pallet is above
the home or loading level, it is moved upwardly from the home level
to deposit the load which is placed on the shuttle table.
FIG. 3 shows the next operation after the load has been placed on
the shuttle table and the cross frame is at the proper level. In
this position the shuttle table is moved forward or to the left to
the limit of its travel, and as previously indicated it would, with
the condition shown in FIG. 1, just clear the top of the pallet by
about an inch, and in FIG. 3 it has about the same clearance above
the previously-formed layer on the pallet.
FIG. 4 shows the next operation in which the restraining bar has
been moved from a raised load-clearing position of FIGS. 1 to 3 to
a load-obstructing position behind the load on the shuttle table.
The shuttle table is moving toward the right as seen in this
figure, sliding under the objects which are now restrained from
moving with the table and crowding onto the pallet, or the
previously-deposited load on the pallet.
With this brief description, the detail of the construction of the
various parts may now be followed.
THE BASE FRAME AND UPRIGHT FRAME STRUCTURE
The base 2, which is best shown in FIGS. 5, 6, 7 and 8, is
generally rectangular in shape and is comprised of elongated
parallel structural side members 10 connected at their opposite
ends by structural cross members 11. Intermediate the length of the
side members, but, as shown in FIG. 7, between the middle of the
length of the rectangle and the right end, there is an intermediate
cross member 12. This provides an almost square open space 13
between the intermediate cross member 12, the left end cross member
11, and the two side frame members 10.
The roller table unit 4 set into this square space 13 which
comprises generally a rectangular frame having main side bearing
bars 15 and end cross bars 16, all rigidly connected together. The
two ends of this frame are here shown as setting on the two side
members 10 of the base (see FIG. 7) with the table frame at one end
being positioned between spaced lugs 17 on one of the base side
frame members 10. However, as hereinafter more fully explained,
this frame may be turned 90.degree. from this position so that the
end cross bars rest on the intermediate cross bar 12 and the left
base end member 11, the frame then being positioned between lugs
17a on the intermediate cross member 12.
The table frame structure 15-16 supports a plurality, preferably
three, spaced parallel roller conveyor units 18 of familiar
construction, there being cross members 19 in the frame 15 and 16
for supporting these roller conveyor units. In FIG. 8 a pallet P of
the usual wooden construction is indicated in position on these
roller conveyors 18 so that the pallet is firmly supported in a
level position, but it can be rolled off the roller table to one
side or the other, the pallet moving of course in a direction at
right angles to the rollers. However, in some plants the floor
arrangement may not accommodate an operation where the pallets are
moved off one side or the other of the base, and in this case, the
table is turned 90.degree. to the position shown in FIG. 7, as
previously explained, and then the conveyors will extend in the
direction of the length of the base, enabling the pallets with
their loads to be moved off the end of the base instead of off one
side or the other. If desired, the roller conveyors may be
power-driven in a manner now well known in the art.
There is an advantage of providing a roller table pallet support
carried by, but separate from the base, since it enables one model
of a machine to fit into the requirements of the plant where it is
used without being specially constructed for its environment. While
this is a desirable feature, it will be apparent that any roller
table could be provided on the base in its place. To enter the
pallet for the loading operation to be hereinafter described, there
are side guides 20 along each side of the roller table. There is
also a movable stop bar 21 provided on a bracket 22, which stop bar
in the horizontal position shown in FIGS. 7 and 8 obstructs the
free movement of the pallet on the roller table when the pallet
abuts it, but as indicated by the arrows in FIG. 8, the stop bar
may be raised in an arc out of pallet-engaging position.
The upright frame comprises two spaced parallel structural columns
25 and 26, preferably of H section with the cross bar of the H
parallel with the base members 10. One of these columns is secured
to each of the base members 10 in line with the intermediate cross
member 12 of the base. Angle braces or gusset plates 27 are
provided for securing them to their respective base structures 10
and keep them perpendicular.
As best seen in FIGS. 5, 6 and 9, the tops of these columns each
have structural plates 28, and there are two structural cross
members 29, one at each side of the columns, secured to these
plates for connecting the tops of the columns and keeping them
parallel.
The cross bars 29 also provide a support for a reversible motor 30,
and reducing gear 31 for driving a cross shaft 32 carried in
bearings 33, one of which bearings is at the top of each vertical
column 25 and 26.
It will be noted that the columns 25 and 26, being of H section and
set with the web or cross bar of the H parallel with the length of
the base, each provide a channel in their respective confronting
faces. There is a sprocket wheel 34 on the shaft 32 above each of
these channels, and each channel has a similar sprocket wheel 34a
(see FIGS. 6 and 9) rotatable about a stub shaft close to the
lowermost end of each column (see FIGS. 9, 10 and 11). A sprocket
chain 35 passes around the top and bottom sprockets 34 and 34a at
each side of the machine, with the two vertical reaches of the
chain being received in the channels of the respective columns.
The motor, reducing gear, shaft, and sprockets 34 and 34a provide
the mechanism for raising or lowering the movable cross-frame
assembly of the machine in the manner to be hereinafter
described.
THE CROSS FRAME AND SHUTTLE TABLE ASSEMBLY
The vertically-movable cross frame comprises two parallel
structural beams 40 of channel section (See FIGS. 5, 11, 12 and
13). They extend through the upright frame with one of the beams
being close to the inside face of each upright 3 so that the
distance between them is slightly greater than the width of a
pallet and about the same as or slightly less than the length of
the roller conveyor units of the roller table 4. As best seen in
FIG. 5, the forward or left ends of the beams extend from the
vertical columns a distance beyond the left side of the roller
table, and their right or rear ends extend beyond or to the right
of the vertical columns an equal or preferably a somewhat greater
distance from the uprights, and well beyond the right end of the
base, so that the base in no way interferes with an operator who
may be loading articles onto the shuttle table. The beams 40 are
connected at the right or rear ends by a cross channel 41, and
there are cross braces 42 (FIG. 11) extending between them
intermediate their ends. There may or may not be a cross bar 43 at
their forward or left ends, but there must be an open space between
them at the left or forward end greater than the area of the
pallet.
Each of these side beams 40 has a vertically-extending side plate
44 secured to the outer face thereof at the location where the
beams pass through the upright frame (see FIGS. 12, 13 and 14),
these plates being interposed between the vertical columns of the
upright frame and the beams. As best seen in FIG. 12, each sprocket
chain has one vertical reach attached to a lug 45 carried on the
adjacent side plate near the top of the plate, and the same reach
is attached to a lug 46 near the bottom of the side plate. In fact
the two ends of the chain end at these lugs 45 and 46 and the side
plate comprises the connecting link between the chain ends. It is
through these connections that the cross frame is moved up and down
in the vertical frame when the chain is driven one way or the
other.
To keep the cross frame free of tipping and level at all times, the
drive chains are not only of even effective length and are driven
in isochronism, but the side plates are guided by smooth,
free-running engagement with the vertical columns 25 and 26. As
here shown, this guiding and steadying arrangement is effected by
at least three rollers on the outer face of each side plate 44.
These rollers 47 are so arranged that the top and bottom ones roll
against one of the inside flanges of the vertical column which they
confront and the intermediate one rolls against the opposite
flange. This staggered arrangement is clearly shown in FIG. 14, so
that the cross frame comprises a vertically-movable cantilevered
truss structure. Each of the flanges of the columns 25 and 26 has a
vertical bearing strip or track 48 on the inner face of the flange
against which the peripheries of these rollers bear (see FIGS. 12
and 13), this track being shown broken away in some figures for
clarity of illustration. In addition to having their peripheries to
hold the platform level, the rollers 47 have shoulders 49 that bear
against the outer edges of the rails 48 to prevent side sway of the
cross frame structure.
To provide necessary adjustment and take up for wear, each roll is
carried on its shaft 50 that passes through a hole 51 eccentrically
positioned in a circular block 52 (See FIG. 15) set in the side
plate 44. The outer end of this shaft is threaded and has a
retaining nut 53 thereon, while the block is clamped in position by
keeper-lugs 54 bolted to the side plates, and which extend over a
shoulder around the circular blocks. By loosening these lugs and
rotating the blocks, the working contact of the roller peripheries
against the track strips 48 can be established and adjusted as
required, and by means of the nute 53, endwise adjustment of the
roller shafts can be made.
THE SHUTTLE TABLE
As best seen in FIG. 12, each side beam 40 has an angle bar 55
secured to its top flange, one leg of the angle bar being vertical
and the other one, resting on the beam 40, being turned outwardly.
Secured by bolts providing stud shafts therefore are a series of
spaced rollers 56 along the inner face of the vertical legs of the
angle bars 55. The peripheries of these rollers project above the
top edges of the angle bars on which they are carried. This series
of spaced rollers, like the angle bars 55 on which they are
carried, extend along substantially the full lengths of beams
40.
The shuttle table 6 comprises a rectangular rigid metal plate 60,
which, as shown in FIG. 12, has its opposite longitudinal marginal
edge portions resting on and supported by the rollers 56 so that
the table may move freely lengthwise along the cross frame. There
are guide strips 61 on the under side of the plate that will engage
the top edges of the rollers to guide the table in its
back-and-forth travel along the cross frame. The table preferably
has a length greater than half the length of the cross frame on
which it travels, since, as seen in FIG. 5, it reaches from the
vertical columns 25 and 26 to the rear or right end of the cross
frame when it is in retracted position. There are stop members 62
on cross bar 41 at the end of the cross frame at a level where it
will limit the rearward movement of the shuttle table, and there
are upright abutments 53 (see FIGS. 5 and 13) at the forward or
left ends of the angles to limit its travel in the forward
direction. The table, which is normally wider than the pallet to be
loaded, has longitudinally-extending side guides 54 secured to the
top thereof, each parallel with, but spaced inwardly from the
adjacent side edge of the table to define the maximum width of the
load, which is usually less than the width of the pallet, and all
objects to be loaded are placed in the flat area of the shuttle
table between these load guides. As indicated in FIG. 13 these
guides may be bolted to the table so that limited adjustment of the
distance between them for variation in load widths may be provided,
as indicated at 65.
As best seen in FIG. 12, there is a cross bar 66 suspended by a
double spring suspension with center bolts 67 at each end from the
lower flanges of the beams 40, this bar being located under the
shuttle table near its forward or left end. It supports bearings 68
for a cross shaft 69 near opposite ends of which are friction
wheels 70. A reversible electric motor and reducing gear assembly
71 at the middle of the cross shaft 69 drives the shaft. The
underside of the plate 60 forming the shuttle table 6 rests on
these friction wheels, so that when the friction wheels are driven
in one direction or the other, the table is driven forward or
backward, as required. The drive, however, is a friction drive, and
the shuttle table is kept on the friction wheels and the rollers 56
only by its own weight. The spring suspension elements 67 are
adjusted to provide the desired frictional contact of the wheels
70, which have suitable friction tires, with the table.
As hereinafter more fully pointed out, this friction drive
arrangement is an important safety factor and the fact that it is
positioned entirely under the shuttle table gives operators full
freedom of access to the table for arranging the successive layers
of objects where one layer will "break joints" with the one
beneath.
THE RESTRAINING BAR ARRANGEMENT
A cross bar 75 extends between the upper portions of the side
plates 44 of the cross frame (FIG. 12). Depending from it are two
spaced arms 76. There is a shaft 77 extending crosswise of the
machine between these two arms with its ends supported in the lower
ends of the arms. Around this shaft there is a sleeve 78 having two
parallel levers 79 attached thereto near its opposite ends. The
restraining bar 80 itself, is secured to the lower ends of these
levers, and it is long enough to extend most of the distance
between the load guides 64 on the table when this bar is in its
lower load-restraining position shown in FIG. 12.
The sleeve 78 also has a pair of closely-spaced lever arms 81
extending therefrom at an angle to the levers 79 and located near
the center of the sleeve. A piston rod 82 forming a part of a fluid
pressure cylinder and piston unit 83 extends between the arms 81
and is pivotally connected thereto. As best seen in FIG. 11, there
is a frame structure bolted to the underside of the center of the
cross bar 75 comprising rigid parallel structural bars 84 with
upturned ends 85, the tops of which are joined by cross piece 86.
This structure provides a bracket with the cylinder-piston unit 83
positioned between its two side parts 84-85, and with the upper end
of the cylinder pivotally anchored at 87 to a lug 88 on the
underside of cross piece 86.
With this arrangement, when the piston rod 82 is fully extended by
the admission of fluid pressure to the upper end of the cylinder,
the restraining bar 80 is in the elevated position well above the
shuttle table, as shown in full lines in FIG. 11, but when fluid
pressure is admitted to the lower end of the cylinder, retracting
the piston rod, the sleeve 78 is rotated to swing the restraining
bar down through an arc of about 90.degree. or preferably perhaps a
little past 90.degree. to the dotted line position shown in FIG.
11.
Since the cross frame is moved up and down, air pressure for
operation of the cylinder-piston unit 83 is supplied from a
connection 90 on the base through a flexible hose 91 to a
connection box 92 secured to one of the beams 40. A tube 93 leads
from this box to a switch valve 94(FIG. 11) where this valve is
closed by a contact shoe 95 on the underside of the rear of the
table. In this position pressure air flows through the valve and
along tube 96, which, as shown in FIG. 12, leads to the top end of
cylinder 83. At this time a second switch valve 97 will vent the
lower end of the cylinder to atmosphere. When the table has moved
all the way forward, the shoe 95 will operate switch 97 to vent the
upper end of the cylinder 83 and supply pressure through line 98 to
the lower end of cylinder 83 to retract the piston in said cylinder
and swing the restraining bar down. It will then stay down until
the shuttle table has retracted and the shoe 95 operates valve 94
to vent the lower end of the cylinder and restore pressure to the
upper end.
Pneumatic valve circuits of this type are well known in the art and
form no part per se of the present invention. The two valves 94 and
97 are so interconnected that when one is admitting fluid pressure
to the cylinder, the other vents the opposite end of the cylinder,
but at intermediate times the pressure is held in the end of the
cylinder to which pressure was last applied.
In most cases, one plant or one apparatus will be employed for one
standard load of objects, so there is provided an indicator to show
the operator the levels at which loads are to be placed. It
comprises a removable panel 100 on the upright column 25. This is
shown in FIG. 10 where the panel has a key slot 101 near its lower
end that engages a stud on the face of the column that is turned
toward the loading end. There is a similar key slot and pin at 102
at the top of the panel (FIG. 9). The panel has markings 103
thereon, preferably comprised of strips of colored tape with a
pressure-sensitive adhesive to removably hold them on the panel to
indicate the levels at which loads are to be placed on the pallet.
An indicating pointer 104 on the adjacent cross-frame side plate 44
will indicate the level to which the cross frame is to be moved.
When the character of the load is changed, the panel may be
removed, the tape markers relocated, and the panel replaced.
Power for the reversible motor 71 on the cross frame is supplied
through a flexible cable 105 leading from an outlet box on the base
to a connecting box 106 on the underside of the cross-frame.
All of the elements to carry out the operations outlined in FIGS. 1
to 4 have been described. It is only necessary to provide switches
to operate the reversible motor 30 to bring the cross-frame with
its shuttle table to the right or home level for loading, then,
after the load is placed on the table, again operate the motor 30
to raise or lower the cross frame to the level just above the level
of the surface on which the next layer of objects is to be placed
on the pallet. After the cross frame has been so raised or lowered,
the reversible motor drive 71 is then operated to drive the
friction wheels in a direction to move the shuttle table to the
left as far as it will go against stops 63, and the friction drive
can drive it no further. The restraining bar will lower at this
time and the motor 71 is reversed to bring the table back to its
starting position, stripping the load from the table onto the
pallet or the previous load on the pallet, as the case may be.
While this sequence of operations may all be effected manually
through the operation of successive switches, it may be so arranged
that all operations will proceed automatically through a full
cycle. This has not been fully shown, but certain parts of the
circuitry is shown.
ELECTRIC CONTROLS
There is an electric control box 110 mounted on the outside of the
column 25 at a convenient height above floor level (see FIGS. 9 and
10). Should it be more convenient, the panel 100, indicators 103
and control box 110 could of course be located on the opposite
column 26. The control box has several buttons on one side, the
uppermost one designated 111 being pushed to connect the apparatus
to a source of operating current, being an "on" button. The next
one, 112, below and to the left as viewed in FIG. 10, is to operate
motor 71 to move the shuttle table on the cross-frame from the
retracted or load-receiving position to its extended position, and
the third button, 113, is pressed to reverse the shuttle table and
return it to the retracted or load-receiving position. Below the
three buttons just described are four others in a vertical row. The
uppermost of these, 114, is operated to move the cross-frame up.
The next lower one, 115, controls the down movement of the
cross-frame. The next lower one, 116, is an automatic cycle switch,
and the lowermost one, 117, is an emergency stop that may be
pressed to instantly stop the machine at any point in its operation
until the start or "on" button 111 is again pressed.
As best seen in FIG. 14, the side of one of the columns, in this
case column 25, there are three limit or flag switches close
together, the center one of which, designated 120, is at the "home"
or loading level of the cross-frame. The one immediately above,
121, is an "up" switch that functions on automatic cycle of the
machine to cause continued upward travel when button 116 is pressed
after initial pressing of "up" button 114. The lowermost one, 122,
continues the downward travel on automatic cycle when the button
116 is pressed following operation of the "down" button 115. These
switches 120, 121 and 122 are operated by an actuator or contactor
123 projecting from the side face of the confronting cross-frame
side plate 44. In addition there is a lower limit switch 124 spaced
below switch 122 which will be operated when the cross-frame has
been lowered to the lowest point of its travel, which is a level at
which the shuttle table 60 will just clear the top of a pallet on
the roller table.
There is a limit switch 125 adjustably positioned on the column 25
at a predetermined level above the home position corresponding to
the maximum height to which the load on the pallet is to be raised
(see FIG. 9).
Referring particularly to FIG. 11, there is a cable 126 extending
from the electric outlet box 106 on the crossframe to a limit
switch 127 adjacent the pneumatic switch 94 arranged to be operated
by the shoe 95 to stop the motor 71 when the shuttle table is fully
retracted and set a reverse switch which will cause it to drive the
table forward when the circuit to the motor is next energized. A
cable 128 leads from outlet or junction box 106 to the motor.
Another cable, 129, leads from the junction box to a limit switch
130 located adjacent the pneumatic switch 97 for operation by the
shoe 95 when the shuttle table is fully extended for stopping the
drive motor 71 and reversing the circuit when the motor is next
energized. These switches and this circuitry is a known type of
circuit in other environments.
In addition there is included in the motor circuit, not as an
essential element, but as an added safety feature, a pair of
switches 131 and 131a, one of which, 131, is at the forward end of
the shuttle table and will operate to stop motor 71 if the shuttle
table should move forward at a level where it strikes the
previously-deposited load, and the other one, 131a, is on the
underside of the shuttle table to de-energize both motors if the
cross-frame and shuttle table are moved down against the load
before the shuttle table has retracted.
Also there are shown two electric eye circuit control units carried
on the cross-frame at the forward end over the roller table area
(see FIG. 13). One of these comprises a light projector 135 that
projects a light diagonally to a photo-sensitive receiver 135a. The
arrow between these elements in FIG. 13 represents the light beam.
This circuit is broken when the light beam is interrupted and
controls the motor 71 so that it will not operate if there is an
obstruction to the light beam at any level. Consequently the
cross-frame must be at a level above the previously-deposited load
on the pallet before the shuttle table drive can operate to propel
the shuttle table forward. It is, however, slightly below the
bottom of the shuttle table, so that as the shuttle table moves
forward, it does not break the light path.
The other electric eye unit comprises a light projector 136 and
photo-sensitive receiver 136a. This is arranged on the opposite
diagonal to the first, the arrow extending between them
representing the other light beam. The circuit for this unit is
closed when the light beam is broken, and open when the light beam
is not interrupted. It controls the cross-frame raising and
lowering motor 30 so that the cross-frame will raise the
cross-frame only so long as there is a load between the cross-beams
so that it will raise above any load and stop when the light beam
is completed, indicating that the cross-frame is at a level where
the shuttle table is clear of the load and needs to be lifted no
higher.
OPERATION
In operating the machine, the cross frame will always at the start
be at the home or loading level. Since the pallet will be empty,
the operator knows that the cross frame must go down from the home
position until the load on the pallet is at or above the home
level. Assuming that the operator is loading parallelipiped
objects, such as cartons or cases, he will have been provided with
a loading pattern so as to break joints in successive layers or
courses on the pallet. He will arrange the first layer on the
shuttle table according to pattern between the side guides 64 back
of the forward edge of the table, preferably roughly in back of the
plane of the raised position of the restraining bar 80. In the
direction of the length of the table, it does not matter if the
articles are not closely spaced when initially put in place because
they will be shoved and crowded together when the shuttle table
pulls back and the restraining bar holds the load.
The operator, after arranging the first layer, and knowing that the
cross-frame must go down, and assuming the "on" button 111 to have
already been pushed, now pushes the "down" button 115. Under manual
control he holds this button in until the cross-frame reaches its
lowermost position. Limit switch 122 prevents the cross-frame from
moving too low. He may then push button 112 to drive the shuttle
table forward, and at this level it will be a slight distance, an
inch or so above the level of the pallet. When the shuttle table
has been moved to its full limit forward, or to the left end of the
cross-frame as here illustrated, the air valve 97 will be operated
by shoe 95 to swing the restraining bar down to the dotted line
position, as described. At about the same time switch 130 will open
the circuit to the table-driving motor 71. Then the operator will
push button 113 to retract the table to deposit the load on the
pallet. The distance between the restraining bar and the forward
edge of the shuttle table in the extended position is such that for
a standard pallet and layer of objects, the table will draw back a
few inches and the first objects will be dropped by the withdrawing
table just at the left-hand edge of the pallet, since the load is
usually flush with the edges of the pallet. When the shuttle table
has fully retracted, the switch 127 will operate to stop the motor
71, and pneumatic valve 94 will raise the restraining bar. The
operator may then push the up or down button as may be required to
bring the cross-frame down to the home or loading level at which
level limit switch 120 will operate to stop motor 30. This motor is
of the self-braking or automatic type so that there is no
overtravel when it is de-energized, and motor 71 is also preferably
of the self-braking construction, such motors being well known in
hoisting apparatus. After one layer of objects has been loaded onto
the pallet and the cross-frame has been returned to loading level,
the operator arranges another load on the shuttle table and the
operation is repeated until such time as the load level becomes
higher than the home or loading level. When this load height is
reached the operator pushes the "up" button first.
After the last layer of articles has been placed on the now fully
loaded pallet, the cross-frame with the shuttle table will be
raised clear of the load, after which the stop 21 (FIG. 8) will be
raised clear of the pallet to enable it to be rolled off the roller
table. Should there be no switch 131 on the shuttle table, or
should it not operate, and through some error the shuttle table
would move forward and strike the load, the cross bar 43 would
prevent displacement of the load, since it would always be opposite
and slightly below the plane of the shuttle table. After the
shuttle table hits the load and loses its inertia, the friction
drive for the table will slip and no damage to the load will
occur.
CONTROL CIRCUIT DIAGRAM
The essential elements of a circuit to effect operation are
disclosed in the diagram (FIG. 16). Automation of these controls to
carry out a complete cycle after a "start" button has been pushed
is simply a matter of adapting relays and electric eye circuits to
open and close the switches of this diagram, or relays in parallel
with them.
In FIG. 16 the motors 30 and 71 are connected across power supply
lines L1 and L2. These motors are controlled through reversing
relay switches 30a and 71a, respectively. The control circuits are
energized by a step-down transformer T having its primary connected
across lines L1 and L2. The secondary has one side connected to a
common return, indicated by the "ground" symbol and the other side
to the line 164, through relay operated emergency "off" switch 117a
which is normally closed, but which is opened by operating push
button switch 117 on the control panel. From 117a the connection to
line 164 includes the manually-operated "on" switch 111 that
energizes the entire control circuit. This switch will remain
closed until pushed again to open the circuit. One terminal of each
of the reversing relays 30a and 71a is connected as indicated by
the ground symbol to the common return. Line 164 leads to flag
switch 116 at the "home" or loading level. For simplicity this
switch is here shown as one which is biased by springs to return to
a neutral middle position after the flag has been moved up or down,
in which position it closes a circuit through line 169 to manual
"up" switch 114 which is in series with normally closed upper limit
switch 125 and relay switch 114a. One terminal of switch 114a
connects through line 114b with the "up" terminal of reversing
switch 30a.
When manual "up" switch 114 is closed, it first energizes magnetic
switch 114c to close this switch, whereupon the motor 30 will be
operated to raise the cross-frame as long as the manual switch is
held closed, but if the frame should by chance go too close to the
top of the upright, limit switch 125 would open the circuit and
close it only if the cross-frame started to lower.
There is a branch line 170 from line 169 that leads to one terminal
of manual "down" switch, which is in series with normally closed
bottom limit switch 122 and relay or magnetic switch 115a, the
second terminal of which leads up through line 115b to the "down"
terminal of reversing switch 30a. When the manual "down" switch 115
is closed, switch coil 115c will first be energized to close switch
115a and the cross frame motor 30 will then be energized to lower
the frame. If the cross-frame starts down or is below the home
position, limit switch 122 will be operated to open the circuit if
the cross-frame should be lowered below its normal operating range.
When the cross-frame travels down from its up position above the
home switch 120 or up from below that switch, it will momentarily
open switch 120 even if switch 114 or 115 is held closed, breaking
the circuit through coil 114c of switch 114a or coil 115c of switch
115a to stop the travel of the cross-frame at this level. Flag
switches 121 and 122 are shunted around switch 120 to be operated
after the vertical frame moves up or down past home position both
for automatic operation and to prevent a condition that would arise
if the switch 120 should be in an "off" position due to slight
overtravel.
Line 164 also leads to one terminal of switch 112 which is the
manual switch for operating motor 71 to propel the shuttle table to
the left from its retracted position, so that when the switch is
pushed closed, a circuit will be completed through this switch to
line 112a and normally closed limit switch 130 to line 130a to
operate motor 71 until the shuttle table at its forward limit of
travel opens limit switch 130 to stop it. When manual switch 113 is
closed, a circuit will be completed through line 113a to normally
closed limit switch 127 to line 127a to operate the motor 71 in the
reverse direction to retract the shuttle table until limit switch
127 is opened by the shuttle table reaching its fully retracted
position.
As before mentioned, there may be two safety switches 131 and 131a
on the forward end of the shuttle table 131 to be actuated if the
shuttle table should inadvertently be moved forward when the
cross-frame was not high enough for the shuttle table to clear the
load. This switch is schematically indicated in the diagram in line
130a. It is normally closed, but upon the forward edge of the
shuttle striking a previously-positioned load on the pallet, it
will open line 130a and stop the motor 71. Switch 131a on the under
surface of the shuttle is arranged to contact the top of the load,
should the table and cross-frame be inadvertently or accidentally
lowered onto the load on the pallet. It is connected from line 164
to the emergency "off" relay 117a in parallel with emergency off
switch so that operation of either switch 131a or 117 to closed
position will open the circuits that control both motors.
The fundamentals of a circuit for manual or semiautomatic operation
of the machine have been here indicated for completeness of
disclosure. To automate these circuits to perform in the manner
hereinbefore described with electric eyes to control up and down
travel and switches to raise the crossframe clear of the load on
the pallet after the last layer has been deposited, involves only
conventional relay circuits which form no part of this invention,
and which have therefore not been shown or described, except some
elements have been included to indicate the capability of so
adapting the machine to a system where, after the operator has
placed a layer of articles on the table, the pushing of one button
will complete the full cycle of bringing the cross-frame to the
proper level, depositing the articles on the pallet and returning
the cross-frame to the home position.
As shown in FIG. 10, limit switch 125 is vertically adjustable,
which is desirable for automatic operation, but for manual
operation it may be fixed, or duplicated as at 125a in FIG. 9.
While the apparatus as above described has been successfully used
in commercial applications, the restraining bar 80 in its lower or
operating position is at the end of lever arm 79 on the sleeve 78,
which, as explained above, is operated by fluid pressure cylinder
83, piston rod 82 and crank arm 81. The thrust against the bar,
particularly with heavier crates or cartons is exerted therefore
through an unfavorable leverage, requiring high pressure in the
cylinder 83 to hold the bar steady when the shuttle table is
retracting and the load is being pushed off. Any slight yield that
allows the restraining bar to delay in starting the discharge of a
load onto the pallet results in the layer being improperly
positioned.
In the modification shown in FIGS. 17 to 20 inclusive there is an
arrangement wherein the restraining bar is on dead center with the
axis about which it pivots when it is in load-restraining or
obstructing position so that the thrust is exerted in the direction
of the length of the lever on which it is carried and resisted in
the studs about which the arms rotate so that only moderate
pressure is required in the operating cylinders for moving the
restraining bar into and out of load-obstructing position. Also the
levers on which the bar is carried are articulated intermediate
their ends in such manner that the bar is thrust forward in the
direction of the load to a slight extent as it moves into operative
position and retracts as it lifts from such position.
In FIGS. 17 to 20 I have shown the mechanism at one side only of
the machine and it is duplicated on the other side. The side plate
44 corresponds to side plate 44 of FIG. 5, and 26 is one of the
upright columns. There is a structural section 75 extending across
the machine connecting the tops of the side plates 44, as in the
structure previously described.
The plate 44 has two vertical rows of equally spaced holes
therethrough at 247 and a mounting block 248 is secured to the
inner face of the plate 44 by bolts (not shown) passing through the
mounting block and side plate 44 and fixed with nuts (not shown).
This enables the mounting block to be fixed at selected levels, so
that its position is adjusted to the load being handled. The
mounting block has a fixed stud shaft 248a projecting therefrom
toward the center of the table. On the stud there is a bell-crank
249 that is pivotally supported on the stud. It has a long arm 250
and a short arm 251.
There is a fluid pressure cylinder and piston unit 252 pivotally
supported at 253 on a second mounting block 254. The block 254 is
bolted to the plate 44, and there are two parallel rows of holes
255 so that the block 254 may be adjustably secured in position
according to the position of the mounting block 248.
At the outer end of the long arm 250 of the bellcrank there is an
extension 256 that is pivoted at 257 to the end of the long arm. As
shown in FIGS. 19 and 20 the arm 250 and the extension 256 have
overlapping half-thickness portions 250a and 256a, respectively,
through which the pivot pin 257 passes. Extension 256 is beveled at
256b to limit the free swing which the extension has on pivot 257
relative to the long arm 250. The joint is a "knee-joint" which
does not permit the extension 256 to swing past an aligned position
with respect to the long arm in an upward direction and can drop
only through a limited arc less than 90.degree. downward from a
straight line position. The arm 250 with the extension 256 is in
effect a toggle lever which increases slightly in length as the arm
250 swings down to a horizontal position parallel with the top of
the shuttle table. When the arm reaches such horizontal position as
shown in FIG. 18, the section or extension 256 rests on a
supporting projection or pin 258.
The restraining bar itself is designated 259 and extends over the
path of travel of the shuttle table. When it is lowered to the
position shown in FIG. 18 the thrust of the object O resting on the
shuttle table which is retracting against the restraining bar 259
is horizontal and is transmitted horizontally through the composite
arm directly against the studs 248a of the two mounting blocks 248.
When the restraining bar is in this position thrust cannot be
exerted in a direction where it may rock the bell-crank on its
pivot so that the cylinders 252 require little more than sufficient
pressure to raise or lower the compound lever arms 250-256 and the
restraining bar 259. A series of holes 258a in each plate 44
enables the support 258 to be raised or lowered as the block 248 is
raised or lowered.
The restraining bar, which is here shown as being of round
cross-section, may be square or rectangular, depending on the load
to be engaged. The arm extension 256 at each side of the machine
has a series of regularly-spaced holes 260 therealong. The
restraining bar 259 can be adjusted toward or away from the pivot
257 at each side of the machine by a bolt that passes through one
of the holes in the extension 256 into the restraining bar at a
selected hole 260. The further back the restraining bar is set
toward the pivot 257, the greater will be the delay in pushing the
object or objects O from the shuttle table moving in the direction
of the arrow to the retracted position. This is important where the
load on the pallet is to overhang the pallet or is to be smaller
than the pallet.
Adjustment of the height of the restraining bar is desirable,
depending on the character of the load. With taller cartons, for
example, it may be desirable that the restraining bar engage the
cartons at a higher level.
Many times cartons are stacked on pallets with cover flaps that are
only partially closed, the flaps being angled upwardly at various
angles between about 30.degree. and 45.degree. or even more from
the horizontal. Using the apparatus herein described on an
automatic cycle, one electric eye system comprising elements 136
and 136a will effect the stopping of the upward travel of the
vertically-movable frame when a light path is clear from one
element to the other, whereupon the shuttle table will be advanced
over the previously-deposited cartons with the partially open
flaps. When the shuttle table reaches its furthest forward position
the circuit for moving the restraining bar into operative position
will also energize a timer that will lower the cross-frame enough
for the underside of the table to press down on the partially-open
flaps of the cartons beneath and substantially close them. Then the
shuttle table is retracted to deposit the next layer of
cartons.
A difficulty with this arrangement is that the electric eye system
merely senses when it rises above the cartons already on the
pallet, but cannot sense whether the flaps are open a little or a
lot and the timer lowers the frame a fixed period of time which may
result in more pressure being applied than is wanted and the
retracting movement of the shuttle table from which its load has
not been discharged may drag on the top layer of cartons already in
place and even disturb the entire load.
In FIGS. 21 to 24 there is disclosed a means for avoiding this
objection. Assuming that the control box and limit switches are on
the vertical frame column 25, this modification discloses a bar 270
extending up along one side of the other column 26. It is supported
on at least two brackets 271 and extends from a distance slightly
above the home level to near the top of the frame. The brackets 271
have slots therein with set screws 272 for securing the bar to the
brackets in such manner that the bar may be adjusted vertically
relatively to the brackets.
The bar 270 has holes 273 therein at regular intervals, preferably
about an inch from center to center. Pins or pegs 274 are removably
set in these holes at regularly-spaced distances. If the cartons
with the flaps folded down are about 12 inches in thickness, these
pins, 274, will normally be on 12-inch centers, but if the cartons
are thicker, they will be placed further apart, and for thinner
cartons closer together.
On the underside of the transverse frame, as for example on the
bottom flange of one of the side frame sections 40 there is a flag
switch 275 that will ride past the pins or pegs 274 when the
cross-frame is moving up, but will be operated by contact with the
first peg it encounters on the way down to stop the travel of the
cross-frame.
The sequence may be followed by reference to the block diagram in
FIG. 4. Current supplied through line 276 and the ground drives
motor 30 upwardly as long as no light flows between elements such
as 136-136a (FIG. 13) and electric eye control unit 136b. When
light passes between the elements 136-136a, indicating that the
elements have been raised above the stack on the pallet with the
last layer having upturned flaps, motor 30, which is raising the
frame will be stopped. At the same time current will flow through
line 277 to drive shuttle table motor 71 in the forward direction.
When the shuttle table has been driven forward to the extended
position, switch 130' will open to stop motor 71 and current will
flow through line 278 and timer 279 to flag switch 275 to the
reverse lead of motor 30. This will start lowering the cross-frame.
When either flag switch 275 is opened by contact with a peg 274, or
the timer opens the circuit, the operation of motor 30 will be
stopped. This will assure of the flaps on the boxes being pressed
down by contact with the underside of the shuttle table, but by
proper setting of the pegs and proper adjustment of bar 270 in its
brackets, the pressure on the flaps will be insufficient for the
cartons to drag against or be dragged by the shuttle table as it
now starts to retract. Various conventional circuits, either in the
nature of time delay relays or other relays responsive to the
opening of the circuit through line 278 may be used for further
sequencing the operation.
The apparatus has a base structure that covers very little floor
area and with the upright frame comprised of two parallel upright
columns, one at each side of the base, both end areas of the
vertically-movable horizontal frame with its shuttle table are
easily approached from three directions without interference from
obstructing columns, at each corner, as is the case with so many
different loaders. Also, since it is necessary in making a safe
load, to break joints at different levels, the loading end of the
shuttle table of the present invention is accessible so that an
operator may lean across it in arranging succeeding layers in
different patterns of the same overall dimensions. The
vertically-movable elongate horizontal frame has the two side
members 40 spaced with a clear opening between them so that the
elongate frame may be lowered to a level where its open end
straddles the pallet placed on the pallet support and when the
frame is so lowered the horizontally-movable shuttle table will be
at a level to just clear the top of the pallet so placed. Once the
load has been built up on the pallet to the home level it is
protected from being toppled over by the side rails 40 at each side
and by the cross rail 43. This is an important security feature
because careless load arranging or placement must be guarded
against. Only when the last layer has been placed on the pallet is
the cross-frame raised above the load after it has reached a height
of more than a few courses.
The friction drive for the shuttle table is also an important
safety feature, as hereinbefore pointed out. Others have attempted
to use fluid pressure cylinders to move a load-carrying table from
one position to another but such cylinders exert a positive force
that is difficult to control if the shuttle table should be
prematurely projected forwardly, or even withdrawn, whereas the
friction drive made possible by applicant's invention provides for
slippage where an otherwise serious impact could occur. In addition
the shuttle table may lift off the cross-frame and the friction
drive wheel 70 will be ineffective to exert sufficient force to the
shuttle table to cause damage. The reversible friction drive for
the shuttle table as here described is therefore an important
safety factor, especially under manual operation. While it is
indicated that only a single layer of objects may be placed on the
shuttle table and transferred to the pallet, there may be two or
three layers placed on the shuttle table, one above another, when
the objects are relatively thin and relatively light. The trolley
elements at each side of the elongate frame with a vertical series
of laterally-adjustable rollers working between the flanges of the
structural columns 25 and 26 provides for the smooth up-and-down
travel of the elongate frame while holding it horizontal and
restraining it from "see-sawing". These and many other advantages
are secured by the apparatus, as will be apparent to those familiar
with material handling.
While the apparatus has been described specifically for loading
pallets, it may be used in loading objects onto supports that are
strictly not pallets. The base may be provided with wheels or
rollers to make it movable, so that in place of loading pallets it
may stack objects in warehouse bins, or possibly freight cars and
trucks, and by placing the rear end against an elevated platform,
the apparatus may be used to transfer articles from a higher level
and arrange them in piles at a lower level, or place them on
conveyors so that the "home" position in this case could be quite
high. However, even if its utility were confined to its primary
purpose, its use will speed up pallet loading in many industrial
environments and substantially reduce the manual labor involved in
this operation.
The four-way valve system that controls the operation of the
cylinder 83 for the restraining bar 80 in FIGS. 1 to 16 is also
used for controlling the operation of the two cylinder and piston
units 252 for the restraining bar arrangement in FIGS. 17 to 20.
Also there may be times when the last layer or tier of objects or
cartons placed on the load must be kept quite steady when the next
layer is being put in place. This is particularly so where the
cartons are small and the upstanding cover flaps must be flattened
down in the manner above described before the succeeding layer is
put in place, because even a slight drag of the cover flaps against
the underside of the retracting shuttle table may displace some of
the cartons.
My invention may provide means for holding the cartons of the top
layer firmly in place at such times. As shown in FIG. 13, a pair of
fluid pressure cylinders 285, preferably air operated, are mounted
on the cross-frame 42 of the elongate frame. Pivoted to the
terminals of the pistons for these cylinders is a bar 286 which is
of a length nearly the width of the layer of objects on the load
and a level below the plane of travel of the shuttle table and an
inch or two more or less below the top of the cartons or objects in
the uppermost tier when the elongate frame is at a level to deposit
the next layer of articles on the load.
There may be a similar bar 287 with fluid pressure cylinders 288 at
the same level on cross bar 43 at the forward end of the elongate
frame.
When the valves 95-97 are operated to move the restraining bar into
position, pressure air is also admitted to these cylinders 285 and
288 to move the respective bars 286 and 287 against the objects on
the top tier of the load and hold them steady until the placing of
the next load is complete and when the restraining bar is raised,
the same operation will operate cylinders 285 and 288 to retract
their respective bars 286 and 287 so that the elongate cross frame
may again move up and down free and clear of the load on the
pallet. A stroke of a couple of inches for moving the bars 286 and
287 is all that is required.
In many cases it may be desirable to clamp the upper tier on four
sides, instead of two, and in this case, as shown in FIG. 13, there
may be movable side rails 289 and 290 at the same level as 286 and
287. They are similarly arranged to be operated by fluid pressure
cylinders 291 and 292 respectively. They of course are in the same
pneumatic circuit as the others to operate in conjunction with
them.
* * * * *