CA1076947A - Guided stretch-wrap machine - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE

This invention is directed to a stretch-wrap machine wherein a motive unit carries a stretch-wrap unit around material to be wrapped. One approach to retaining a number of packages on a pallet has been steel banding. Steel bands were placed around the packages and the pallet and the bands tightened and clamped. The problem with steel banding is that loads can be crushed. Furthermore, the steel bands are difficult and dangerous to handle. Shrink wrapping has also been used, but requires special equipment for causing the shrinkage. Further, it cannot be used in cold rooms or other areas where high heat loads are objec-tionable. Also, it cannot be used over polyethylene wrapped pack-ages because of sticking between the shrink wrap material and such packages. Machines which wrap stretch-material have been developed.
However, these machines cannot be effective unless the load is small enough to fit on a turntable. To overcome these disadvantages, the present invention provides a motive unit which carries stretch wrap unit around stationary material to be wrapped. The motive unit Is preferably self-propelled and may be self-guided by means of a track follower, although manual motive unit guide controls can be pro-vided. Alternatively, the motive unit may be self-propelled and biased to be self-guided around the unit to be wrapped. In such embodiment, a follower wheel contacts the unit to be wrapped and controls its steering. A propulsion urges the motive unit toward the material to be wrapped.

Description

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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

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 ., .
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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.

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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.
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~ 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_ `,'' .
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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 . :

--`` 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-'' .
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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 --` 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 : , 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.

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Claims (12)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. 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 sur-face 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 there-with 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.

2. The stretch-wrap machine of Claim 1, wherein said feeler means projects from one side of the vehicle and said means for supporting the vehicle comprises a propulsion wheel on the oppo-site side of the vehicle, and wherein said driving means, including said biasing means, comprises means for propelling said wheel.

3. The stretch-wrap machine of Claim 2, wherein said means for supporting the vehicle also comprises an additional wheel at said one side of the vehicle.

4. The stretch-wrap machine of Claim 1, wherein said means for supporting the vehicle comprises at least one propul-sion wheel and at least one steerable wheel, and wherein said means for driving the vehicle comprise means for propelling said propul-sion wheel, said biasing means comprising means for urging said steerable wheel to steer toward the material to be wrapped.

5. The stretch-wrap machine of Claim 4, further com-prising means connecting said feeler means to said steerable wheel for steering said steerable wheel in accordance with the shape of said surface engaged by said feeler means.

6. The stretch-wrap machine of Claim 4, wherein said biasing means comprises a spring connected to said steerable wheel.

7. The stretch-wrap machine of Claim 1, wherein said feeler means has a roller for engaging said surface.

8. The stretch-wrap machine of Claim 7, wherein said roller is of adjustable height to adjust the level at which the roller engages said surface.

9. The stretch-wrap machine of Claim 1, further comprising means for counting the number of revolutions of said vehicle about the material to be wrapped.

10. The stretch-wrap machine of Claim 9 wherein said counting means comprises means for counting the number of corners of the material to be wrapped that are passed by the vehicle.

11. The stretch-wrap machine of Claim 10 wherein said means for supporting the vehicle comprises a steerable wheel, wherein said biasing means comprises means for urging said wheel to steer in a direction toward the material to be wrapped, and where-in said counting means comprises means responsive to the steering of said wheel as the vehicle passes a corner of the material to be wrapped.

12. The stretch-wrap machine of Claim 9 wherein said counting means comprises a sensor mounted on said vehicle and a sensor actuator fixed relative to the material to be wrapped and positioned to actuate the sensor each time the vehicle has completed a revolution about the material to be wrapped.