Note: Descriptions are shown in the official language in which they were submitted.
9'~7
.
This invention is directed to a stretch-wrap machine wherein
a motive unit carries a stretch-wrap unit around material to be wrapped.
Modern mechanized handling requires that a number of small
packages be packed together so that they can be handled in larger units.
Pallets are used as a base, and packages are stacked on the pallet to
a conventent size and weight for mechanTcal handling. One approach to
retaining the packages on the pallet has been steel banding. Steel
bands were placed around the packages and the pallet and the bands
tightened and clamped. The problem with steei banding is that loads
can shift, and under the wrong circumstances, all the packages on the
outer extremlties of the load directly under the steel bands can be
crushed. Furthermore, the steel bands are difficult and dangerous to
handle. Steel bands are most useful on heavy metal objects, such as
pipe and other forms of steel. It must be noted that steel banding
does not provld~ any weather protectlon for the packages.
A newer method of securlng packages on a pallet to provide
a palletized load is to shrlnk wrap the packages and the pallet. In
thls arrangement, bags are made out of shrink material (usually
polyethylene), and the bag is placed over the palletized packages.
Thereupon, the bag is subjected to heat whereupon it shrinks to unitize
the palletized load. Shrink wrap is useful for loads which are of
uniform size, but requires special equipment for causing the shrinkage.
Since heat is used to cause the shrinkage, it cannot be used in cold
rooms or other areas where high heat loads are objectionable. Further-
more, it cannot be used over polyethylene wrapped packages because of
stlcking between the shrink wrap material and such packages.
To overcome these disadvantages, stretch-wrapping has been
developed. In these machlnes, Dne of which is seen in Lancaster
Patent 3,867,806 a stack of packages is placed on a turntable. Usually,
these packages are mounted on a pallet. The turntable is rotated, and
the palletized load of packages is wrapped with a stretch-wrap material.
This material may be polyethylene or polyvinylchloride web or film and
is manufactured to be able to stretch at least 25 percent. During
76~7
wrapping of the load, tension on the stretch-wrap film provides
a tension which stretches the film from 15 to 25 percent. The
film is thin, usually about l/lOOOth of an inch, and the load
is wrapped with as many thicknesses as is necessary to obtain
the desired unitized load strength.
The stretch-wrap film may be as tall as the load or
may be narrower than the height of the loadO In the latter
case, the narrower film is spiral-wrapped around the load.
Since more wraps are necessary at the top and bottom of the
~.
load than at the middle for best strength, this is more
economical of material. However, these stretch-wrapped concepts
have been limited to those loads which can be placed on the
turntable and rotated.
In order to aid in the understanding of this
invention, it can be stated in essentially summary form that it
is directed to a stretch-wrap machine comprising: a vehicle
including, as components of the vehicle, means for supporting
the vehicle for free movement along the floor, means for driving
the vehicle along the floor around material to be wrapped,
said driving means including means for continually biasing the
vehicle to move in a direction toward said material without
external guidance, and feeler means projecting in said
direction for engaging a surface associated with said material
in response to said biasing and thereby limiting the movement
of the vehicle toward said material, and a stretch-wrap unit
mounted on the vehicle for movement therewith along the floor
and including means for wrapping stretch-wrap film around the
material to be wrapped as the vehicle travels on the floor
around said material.
~` 30 It is thus an object of this invention to provide a
guided stretch-wrap machine which is capable of moving around
A
9 076947
material to be wrapped so that the stretch-wrap on the motive
unit can be released with controlled tension to wrap stationary -~
material loads. It is a further object to provide a stretch-
wrap machine wherein the stretch wrap unit is moved around the
structure of material to be packaged with the wrap while the
material to be wrapped stands stationary.
It is a further object to provide a stretch-wrap
machine motive unit which is capable of being guided around the
structure to be wrapped by any one of a plurality of selectable
motive unit guidance means.
It is a further object to provide a stretch-wrap
machine
., .
;,
.~
-2a-
,. ~
.~, . ' ~
6947
which is capable of stretch-wrapping irregular loads or large loads by
travelling around the load while releasing stretch-wrap film. It is
another object of this invention to provide a stretch-wrap machine which
Ts economic of use and is capable of wide utility in the k7nds of loads
~t can wrap.
It is a further object to provide a stretch-wrap motive unit
which is guided around the structure of material to be wrapped by con-
tact with the structure or with its support.
It is a further object to provide a stretch-wrap machine
whsrein the motive unit has a follower which contacts the materTal to
be wrapped or with its support so that the motive unit is guided in its
circuit around the material by steering sensing contact therewith.
It Is another object of this tnvention to provide a motive unit in a
stretch-wrap machina wherein the propulsion of the motive unit is
blased so that the mot7ve unit Is propelled In a direction which tends
to propel It in a path around the materlal to be wrapped. It is a
further obJect of this invention to provide a stretch-wrap machine
which is economlc of use and is capable of wide utility in the kinds
of loads it can wrap without the need for permanent or expensive in-
stallations devoted to the purpose.
The features of the present invention which are believed tobe novel are set forth wtth particularity in the appended claims. The
present invention, both as to its organization and manner of operation,
together with further obJects and advantages thereof, may be best
understood by reference to the following description, taken in con-
junction wlth the accompanying drawings.
FIGURE I is a perspective view of a preferred embodlment of
the stretch-wrap machine of this invention.
FIGURE 2 is a top-plan view of the stretch-wrap machine of
FIGURE I showing it optically guided on a circular track and proceeding
around a load beTng stretch-wrapped.
FIGURE 3 Is similar to FIGURE 2, but showing the machine
opt1cally following an elongated track to stretch-wrap an elongated load.
-3-
:,
i947
.
FIGURE 4 is a side-eievational view of the structure shown
in FIGURE 2, as seen along the line 4-4 of FIGURE 2, showing the vertical
organlzation of the machine.
FIGURE 5 schematically shows a top-plan view of another pre-
ferred embodlment of the stretch-wrap machlne where it 7s manually
guided on an irregular travel track by the operator.
FIGURE 6 shows another preferred embodiment of the stretch-
wrap machine where the machine is provided with a mechanical follower
- and follows a mechanical track.
FIGURE 7 is a perspective view of one embodiment of the
mechanical track guide mechanism.
FIGURE 8 is a schematic top-plan view of an embodiment of
the stretch-wrap machine of this invention wherein it follows a guide
track by electromagnetTc coupling.
FIGURE 9 i5 a fragmentary perspective view of another
mechanlcal guide structure whereln a pin on the machlne follows a
recessed track.
FIGURE 10 is a side-elevational v7ew of another preferred
embodiment of the stretch-wrap machine of this invention wherein optical
scanning by the machine of coding on the structure being stretch-
` wrapped guides the stretch-wrap machine.
FIGURE 11 is a schematic diagram of the system for guidance
: illustrated in FIGURE 10.
:.
~ FIGURE 12 is a perspective view of a second preferred
`;; embodiment of the stretch-wrap machine of this invention.
,: FIGURE 13 is a top plan view of the stretch-wrap machine of
,~ FIGURE 12 wTth parts broken away to show the steering mechanism.
; FIGURE 14 is a top plan view similar to FIGURE 13, but showing
the stretch-wrap machine starting around a corner of the material to be
:.
wrapped, by means of its self-guidance.
FIGURE 15 is an enlarged elevational view, with parts broken
away, taken generally along the line 15-15 of FIGURE 13.
A first preferred embodiment of the stretch wrap machine 10
. _4_
`,''
.
. i ' ' ~
1~7~947
is illustrated in FIGURE 1. It comprises motive unit 12 which carries
on its top stretch-wrap control unit 1~. Motive unit 12 has frame r6
which is supported on front wheels 18 and 2G and rear wheels 22 and 24,
see FIGURE 3. The wheels support the stret-ch-wrap machine with respect
to floor 26 as well as propel and guide the machine on the floor. All
four wheels may steer (as is shown in FIGURE 2) to aid the machine in
making turns, and all four wheels may propel the machine on its course.
On the other hand, the propulsion and steering function may be separated
with some of the wheels steering and some of them propelling. Further,
the motive unit may be structured so that one wheel propels and steers
and provides a major part of the support, while two other wheels merely
support. The configuration of the motive unif shown is merely
illustrative, and it need only supply the functions of controllable
forward propulsion and guidance of the stretch-wrap control unit 14.
With the present stretch-wrapping invention, the wrapping
materlal is wound a number of tlmes around the matertal to be wrapped,
which is stationary. The control of the path of the motive unit can be
accomplished in a number of different ways. In the motive unit 12,
given as a preferred example of a motive unit, front wheels 18 and 20
are steerable. In the first manner in which the stretch-wrap machine
10 can be moved around a stat70nary material to be wrappedj the
steerable front wheels 18 and 20 are directed at a predetermined
steering angle, as indicated by steeing indicator 28, to move the
stretch-wrap machine around a circle of known radius and is locked so
that the machlne continues to move in a circle. Battery 30 powers the
propulsive rear wheels. In this way the stretch-wrap machine moves in
a circle around the stationary material to be wrapped.
When there are a number of circuits around the circle, it
can be seen that the clrcular path of stretch-wrap machine 10 may drift
with respect to the stationary material to be wrapped, and such is un-
desirable. Thus, instead of being locked on a particular radlus, the
motive unit might be directed by manual control of manual steering
handle 32 which controls the steerable front wheels through steering
-5-
. :
--`` 10~947
servo 34. Steering servo 34 is in effect a power steering unit which
can receive signals for steering or guiding of the motive unit to direct
the motive unit on the desired course. When manual steering handle 32
Is used manual control 36 of the propulsion of the motive unit can also
be used.
it is thus seen that motive unit 12 can be moved a plurality
of times around a stationary assemblage of material to be wrapped.
FIGURES 2 and 4 illustrate a plurality of packages stacked on a pallet
as the material to be wrapped and the material is identified in those
figures generally at 38. Stretch-wrap control unit 14 includes up-
right rails 40 which carry movably reciprocatable carriage 42. Carriage
42 carries stretch-wrap material roli 44 which is totatably wrapped for
controlled letoff tension by means of tension control unit 46. Web 48
is let off stretch-wrap material roll 44 under controlled, predetermined
tension. As described in the background, web 48 may be sufficiently
wide to fully engage the helght of materlal 38 or It may be narrower
than the helght of materlal 38, as shown in FIGURE 4. In this case,
carriage 42 is propelled up and down its rails 40 to spirally wrap
material 38, as shown in FIGURE 4. Additional wraps may be laid around
the top and bottom of material 38 to give additional strength to the
packaglng. ~over sheet 50 may be laid over material 38 prior to the
peripheral wrapplng to protect the top of material 38. As the web 48
Is spirally wrapped upward on the material 38, it engages around the
edges of the cover sheet to supply some protection to materlal 38.
With this organization, it can be understood that manual control
of motive unlt 12 in its course around the material 38 to be wrapped Is
time-cons~ming. Furthermore, locking the steering may produce un-
desirably uneven passage. Thus, more controlled means for control of
; the directlon of the motive unTt is desirable. In FIGURES I through 4,
the preferred guidance of the motive unit is by optically following a
gulde track. Guide track 52 is In the form of a painted strip or an
applled tape layer, or the like of optically differlng characteristics
than floor 26. The difference can be in color, brightness, or reflec-
-6-
'' .
.
76~47
tivity so that the different characteristics can be optically detected.
t)ptical tracker 54 is mounted on the front of motive unit 12 and the
detectors 56 and 58 laterally spaced thereon. The detectors detect the
edges of the guide track and steer motive unit 12 through servo 34 and
back so that both of the detectors are over the track. Guide track
52 is seen in FIGURES 1, 2 and 4 as circular while guide track 50 in
FIGURE 3 is rectangular in configuration with curved corners. Guide
track 60 is of particular use in wrapping an elongated stationary load
62 of material to be wrapped, for example, a long crate or a couch or
other similar piece of furniture. Thus, the optical guide track is a
; convenient way to guide the stretch-wrap machine as it traverses its
path. t'ontrol unit 64 on stretch-wrap machine 10, as seen in FIGURE 1,
controls the speed and the number of circuits the machine makes around
the stationary load to be wrapped in conjunction with the traverse of
carriage 42 on its gulde so that the desired amount of overlap end the
desired number of turns in stretch-wrap, as well as the desired stretch-
wrap tension are achieved.
FIGURE 5 illustrates that stretch-wrap machine 10 can be
guided around an irregular load 66 to be wrapped by means of a separate
manual control 68. Manual control 68 is in the form of a joystick which
can be controlled by the operator as he stands beside the wrapping
operation. Such joystick operation saves operator tlme and effort, and
the operator can be working at other tasks tsuch as starting or guiding
another stretch-wrap operation with another stretch-wrap ~achine 10
adjacent the first one), and thus his time can be doubly utilized.
A separate manual control, as illustrated in FIGURE 5, can be especially
useful when each of the loads is of a different size, shape and con-
figuration. In this embodiment of greatest flexibility, the carriage
traverse of the stretch-wrap material can elso be controlled from
manual control 68.
In more permanent installations where the size and shape of
the material to be wrapped is more uniform over a longer period of time,
a mechanical guidance track can be used. In FIGURE 6, a stretch-wrap
--7--
--` 1076947
machine 10 is guided around material-to-be-wrapped 70 on circular guide
track 72. The guide track 72 is an upstanding ring and is secured to
the corners of the load of material 70 so that the position of the
track is directly related to the position of the material to be wrapped.
Track follower 74 has rollers which follow the upstanding track 72. Track
follower 74 has rollers which follow the upstanding track 72. Track
follower 74 is mounted on control arm 76 which is secured to machine
10 so that machine 10 follows an appropriate circular path around the
outside of track 72.
- 10 In FIGURES 7 and 8, guide track 78 is an upstanding rail
mounted on the floor 26 outside of the area in which the load to be
wrapped is located. Track follower 80 is secured to the front of
stretch-wrap machine 10 and guides the machine around the track.
Guldance may either be by direct guidance (in which case the front
wheels of the machine are casters) or may be in control of servo 32
for steerlng and guidance of the machine around the track. The track
may be clrcular or rounded rectangular, as illustrated in FI~URES 7
and 8.
FIGURE 9 illustrates stretch-wrap mach'ine 10 as being guided
on a U-shaped track 82. In this case, the track follower is pin 84
~' which is mounted on the front machine and engages in the track to
' follow the track and guide the machine. The track follower may be
rlgidly secured to the front of the machine for its guidance, in
which case the front wheels of the machine are casters, or the track
follower pin may be movably mounted to control servo 34 which in turn
' steers the front wheels to follow the track. As shown, track follower
pin 84 can be lifted out of the track and turns to lock out of the way
' when track followlng is not desired. Track 82 can either be recessed
into the floor 26, as shown as being the preferred structure, or may
be mounted on the top of the floor. On the top of the floor, gulde
. , .
` track 82 is cheaper and easier to install and is more easily changed,
but Is in the way if a more level floor surface is desired.
FIGURE 10 illustrates stretch-wrap machine 10 being guided
1~7~947
around load 86 of material to be wrapped. In this case~ strip 88 of
digital coding is positioned around the load, and sensor 90 on the
machine is brought up to the digital coding. Control system 92 on
rnachine 10 (see FIGURE il) interprets the digital coding, guides the
motive unit, and controls the stretch-wrap control system. In this way,
flexibility is achieved in that no track is required on the floor, but
digTtal coding for each set of material to be wrapped controls the
stretch-wrap machine so that an optimum wrap is achieved in each case
without the need for personal attention to the machine. In this case,
the digital coding is a track which is followed by the stretch-wrap
machine, and the track (in addition to controlling the path of the
machine) also controls the wrap tension and carriage traverse for
optimum wrap conditions.
Control unit 64, shown in FIGURE 1, has similar characteristics
in that it controls the stretch-wrap unit 14 as a function of progress
of the motlve unit along its path. As previously descrlbed, the spiral
wrap is a function of position, and thus control unit 64 is a similar
type of interrelating computer. It may be digital or analog, depending
on needs.
The combination of the stretch-wrap unTt with its controls,
together with a motive unit which moves the stretch-wrap unit around the
stationary load of material to be wrapped thus provides great advantages
because the size or balance of the load is of no limTtat7en to the
wrapping thereof. Furthermore, the equipment Is economic because it
can be used in wrapping different configurations in different areas.
In fact, the stretch-wrap machine may be taken to the assemblage to be
wrapped, rather than having to bring the assemblage of materials to the
wrapping machine. Thus, the stretch-wrap machine 10 can be used to
wrap similar packages to those previously wrapped> but can also be uses
in other locations for wrapping other structures so that the utility of
stretch-wrapping is very much broadened.
A second preferred embodiment of the stretch-wrap machine 10
is shown in FIGURES 12, 13 and 14. The stretch-wrap machine 10 comprises
- , -: ' '
~1~7~9~7
motive unit 12 and stretch-wrap unit 14. The stretch-wrap unit îs mounted
on the motive unit, and the purpose of the motive unit is to move the
stretch-wrap unit around the material to be wrapped. In FIGURES 12
through 14, the material to be wrapped is indicated at 38 and, in
FIGURE 15, it is Illustrated as being positioned on pallet 39. The
material to be wrapped can be a wide variety of different types, from
one large carton which needs strengthening, water-proofing, or secure-
ment to its pallet, or may be a stack of smaller cartons or bags which
need to be held together and/or also held onto a pallet to make the
load stable. On the other hand, the material to be wrapped may not be
packaged, but may be furniture or the like which needs to be wrapped to
protect it in storage or shipping. The material to be wrapped is placed
: on the floor 21, see FIGURES 12 and 15, and i5 positioned away from
walls, posts, or other equipment sufficiently far that the stretch-
wrap machine 10 can move around it.
Stretch-wrap unit 14 Is illustrated as carrying roll 23 of
stretch-wrap film 25. The stretch-wrap unit releases film 25 with
appropriate tenslon as the motive unit carries the stretch-wrap unit
around the material to be wrapped. When the width of film 25 in the
height direction is sufficient to properly wrap the material to be
wrapped, then no spiral traverse of the stretch-wrap roll is required.
However, for illustrative purposes, rails 27 carry carriage 29 upon which
roll 23 is mounted for tensioned release. Motor 31 moves the carriage
along its rails as the motive unit moves so that spiral wrapping is
achleved, as indicated in FIGURE 12. In this way, wrapping of a tali
load of material to be wrapped is accomplished. Control cabinet 33
houses the controls for the various motors and control of the tenslon,
if such Is required.
Motive unit 12 is supported on four wheels. The rear wheels
30 35 and 37 are mounted on axle 39, which is mounted on bearings on the
bottom of platform 41 of the motive unit. Motor 43, see FIGURES 12 and
13 is connected through reduction gear 45 and belt or chain 47 to drive
axle 39. Motor 43 is controlled by appropriate controls in control
-10--
: ,
1~)76947
cabinet 35. The switches and knobs on the cabinet can control the on-
off function of the motor and the speed at which it propels the motive
unit.
Batteries may be provided in housings 41a to supply power to
the propulsion motor, the stretch-wrap carriage motor9 and the control
system so that the stretch-wrap machine is self-powered and is completely
independent of any external power supply.
Only left rear wheel 35 is keyed to axle 39, as by key 49.
Wheel 37 is freely rotatable on the axle so that the propulsion of the
motive unit tends to urge the motive unit in a clockwise circle when
the motive unit moves to the left, as seen in FIGURE 13. Other motive
means can accomplish this result. For example, the right rear wheel
can be a caster, while belt 47 directly engages a pulley on the insTde
of wheel 35, which would be freely rotatable on a stub sheft. On the
other hand, both rear wheels could be driven but with much hlgher
propulsion force on the left rear wheel 35 than on the right rear wheel
37 by the use of a special, unbalanced differential. Such a differential
could place any desired fraction of the propulsion force on the left
rear wheel, but the right rear wheel could also contribute toward
motlvation to optimize stretch-wrap tensTontng.
Front axle 51 is plvoted on vertical steering pivot pin 53
on the bottom of platform 41 adjacent the front end thereof. Front
wheels 55 and 57 are freely rotatably mounted on the front axle. Spring
59 is connected to the axle to bias the axle to urge it to steer the
motive unit to Take clockwise circles, as shown in FIGURE 14. Thus,
steering is blased in the same direction as is the propulslon of the
motive unTt. In the preferred embodiment thus described, both the
propulsion and steering are baised for turning the motive unit. In
optimum circumstances, the bTasing of only one of these turning forces
may be satisfactory.
Feeler arm 61 carries follower roller 63 on the front end
thereof. The arm is configured so that follower roller 63 is positioned
to follow along the side of the material 38 to be wrapped and counteract
--I I--
1~765~47
the clockwise turning moment provided both by the propulsion unit and
the bias steering. Roller 63 engages the side of the material 38 in re- -
sponse to the biasing of the motive unit toward the material and provides
a counteractlve force which limits the movement of the motive unit to-
ward material 38 and causes the motive unit to follow along the side of
the material 38 without further turntng toward it. Any further turning
toward it would cause the follower roller 63 to turn the steering wheels
out so that the motive unit is self-guided from the material 38. The
straight-ahead direction along the straight edge of the material 38 is
: 10 shown in FIGURES 12 and 13. FIGURE 14 shows that when follower roller
; 63 reaches the corner, the bias of the steering and the bias of the
propulsion causes the motive unit to immediately turn around the corner.
In this way, the motive unit carries the stretch-wrap unit around and
around the material 38 to be wrapped. As the motive unit Ts drlven
along the floor around the material to be wrapped, either by the
propulslon alone or in conjunction wtth the steering, it is clear that
; the stretch-wrap film wraps the material for its secure packaging and
protection.
Switch 65 is positioned on the underside of platform 41 and
has dog 67 extending from the bottom thereof. This dog is contacted
by feeler arm 61 each time the feeler arm and the steering turn far
enough for the stretch-wrap machine to go around a corner, as shown in
FIGURE 14. Switch 65 is connected into control cabinet 33 wherein the
corners are counted. When the desired number of corners has been
negotiated so that stretch-wrapping is complete, the machine can thus
shut itself off. In this way, stopping can be automatically accomplished.
In some cases, the material to be wrapped does not have corners
or is oddly configured so that the corner-counting switch 65 is not
applicable. Accordingly, arm 61 is provided with a sensor or switch 66
depending therefrom and adapted to make contact with a switch actuator
block 21a. Thus, block 21a is disposed between the path of the motive
unit and the material to be wrapped so that arm 61 passes over block 21a
once per wrapping revolution or turn Switch 61a which 1s actuated by
'.'
:`
'
~[)76~47
such passing contact~ is connected into control cabinet 33 wherein the
revolutions or turns are counted so that the machine can shut itself off
when the stretch-wrapping is completed. It should be noted that the
location of switch 61a on arm 61 is for ease and convenience, since sensor
or swTtch 61a also may be locatable on an auxiliary arm mounted on the
motive unit and directed to port or starboard with respect to the motive
unit so as to pass over the appropriately located actuator block 21a.
Also, other conventional sensing means, including optical and electro-
magnetic, for example, can be used instead of switches 65 or 61a, with
corresponding changes in the actuatory therefor.
In view of the fact that different ~aterials to be wrapped
may have dlfferent characteristics adjacent their lower edge for the
~ follower roller to follow, the follower roller 63 can be provided with
; vertical adjustment. As is seen in FIGURE 15, adjustable leg 69 has
floor-followTng roller 71 on the bottom thereof. By adjustlng the
height of leg 69, the height of follower roller ~ above the floor is
adJusted. When the load is palletized, of course, follower roller
63 must be above the pallet openlngs. Another way of accomplishing
the desired result is to have a fairly tall follower roller 63
supported by a floor roller so that the follower roller engages the
highest point, whether the pallet or the pallet load.
This invention having been described in its preferred
embodiment, it is clear that It is susceptible to numerous modifications
and embodiments within the ability of those skllled in the art and
without the exercise of the inventive faculty. Accordingly, the scope
of this invention faculty. Accordingly, the scope of this invention
is defined by the scope of the following claims.
:
