WO2010103214A1

WO2010103214A1 - Mobile stretch-wrapping machine with rotary arm

Info

Publication number: WO2010103214A1
Application number: PCT/FR2010/050353
Authority: WO
Inventors: Pierre Bonnel
Original assignee: Deo Wrap Service
Priority date: 2009-03-09
Filing date: 2010-03-02
Publication date: 2010-09-16
Also published as: FR2942776B1; FR2942776A1

Abstract

The invention relates to a mobile stretch-wrapping machine with a rotary arm that comprises a jib (12) carried by a forklift (T) with a fork (8) for pallets and, under said jib, a rotary arm connected to a vertical column (11) having slides (14) on which a stretch-wrapping head (U) can slide. According to the invention, and in order to decrease personnel fatigue and improve the hold of the load (52) placed on a pallet (50) and wrapped with a film (61), the forklift (T) is that of a pallet truck and is provided with means (2-4) for moving in translation in a horizontal plane and has an electric motor (4) powered by rechargeable batteries (5), while the branches (8a-8b) of the fork (8) are connected to the fixed frame (6) bearing the jig (12) and each bear a lift arm (40) capable of vertical movement forklift means (7) between a) a fork engagement position in which the arms (40) bear on the fixed branches (8a,-8b) of the fork (8), and b) a lifting position in which each arm is vertically remote from the fork engagement position by a distance L substantially equal to the value of the height of a pallet (50) without a load so that the wrapping can be carried out around the bottom of the pallet.

Description

Mobile wrapping machine with rotating arm

The invention relates to a mobile wrapping machine with a rotating arm for wrapping loads on a pallet.

Devices of this type are used in general purpose warehousing warehouses and at the picking station for delivery to the retail stores. Traditionally, the preparer picks the packages from the storage shelves and places them on a pallet that he moves with the help of a cart, motorized or not. During the selection and loading operation, the preparer takes care of arranging the packages in the template of the pallet, so that, despite the different volumes of the packages constituting the load, they do not extend beyond the pallet. When the loading is finished, the joining of the packages between them, for example to have a good behavior during their transport to the store of sale, is ensured by a stretch film wrapped around them, forming turns which are superimposed. This wrapping operation is ensured: either by a fixed installation comprising, as described in the documents FR2695102 and WO2007 / 010341, on the one hand, a rotary plate on which the loaded pallet is deposited, and, on the other hand, a station wrapping system occupying a fixed position relative to the plate and whose frame carrying the film reel is movable vertically over the height of the load to ensure its wrapping, this frame may comprise in situ pre-stretching means of the reel and means of adjustment of its laying voltage; or by an apparatus carrying the coil and moving around the pallet and its load, this apparatus having no pre-stretching means, nor means for adjusting the laying tension.

The invention relates more particularly to the latter technique of wrapping, because it does not require to reserve an area of the warehouse to perform this operation, as is the case with a fixed installation. Indeed, this banding technique can be practiced in an unobstructed area of the warehouse, as soon as the pallet has reached its maximum load, with the advantage of limiting the movements in the warehouse between different specialized stations and to improve the productivity .

In moderately equipped warehouses, the wrapping is carried out either, as described in WO99 / 01347, with a manual reel manually moved around the load, or, as described in WO99 / 01347 and WO01 / 98152, with a wrapping head carried by a carriage that the preparer moves around the load to form between 12 and 15 turns. To reduce the fatigue of the staff, but also the time spent carrying out this wrapping, while improving the regularity of the winding and maintaining the load on the pallet, appeared devices mounted on a carriage and whose chassis includes, as described in document DE10220803: a fork positioning itself under the pallet,

- a bracket arranged above the fork,

- a rotating arm mounted under the gallows,

and, carried by this arm, a column carrying a vertically movable wrapping head. This device, which is carried by a manually movable carriage, is distinct from the apparatus used to prepare the order by moving between the parcel storage areas, which apparatus is increasingly constituted by a motorized fork carriage, commonly referred to as "Pallet truck". It follows that to ensure the wrapping of the load, it is necessary that the loaded pallet is removed from the fork of the pallet truck and taken again by that of the wrapping machine. This transfer requires unnecessary physical effort and time and yield losses.

A first object of the invention and to overcome these disadvantages.

Furthermore, in wrapping machines with rotating arm and vertically movable wrapping head, it is very difficult to bind the load to the pallet by means of the film strip, since the fork which is inserted in the pallet, prevents that the lower edge of the strip unwinding from the reel comes above its upper level. As a result, the film clings only on the upper edge of the pallet plate, and not on the height of this pallet, which is insufficient to ensure the perfect retention of the entire load, for example when this one is subjected to dynamic forces during its movement by a vehicle.

To remedy this insufficient connection between load and pallet, the forklift truck and manual movement described in DE10220803, comprises, near its stem and in each of the two branches of the fork, a transverse groove for the passage of the base of the film reel, between the stem and the load, during the rotation of the articulated arm. This increases the downward stroke of the spool and lowers the level of the lowest film spire. However, this is still insufficient to obtain a perfect connection between the load and the pallet that carries it.

A second object of the invention is to provide means allowing the wrapping band to wind at least over most of the height of the pallet, to actually secure the load with the pallet. Finally, the present-day stretch wrapping machines do not have means for pre-stretching the reeled web of the reel, so that they use already pre-stretched film having the following disadvantages:

- smaller clamping memory than with a stretched film just before laying, - set length of tape equal to the tape length wound on the reel, ie around 600 meters, thus requiring frequent changes during the day and wasted time

- use of a single supplier to obtain coils adapted to the installation conditions. A third object of the invention is to provide an apparatus for using non-pre-stretched standard coils from all manufacturers and whose pre-stretching done just before the load is wrapped, improves load clamping, increases the rollable tape length, reduces the number of stops and time wastes for coil replacement. For this purpose in the wrapping machine according to the invention, the carriage is provided with translational displacement means whose electric motor is powered by rechargeable batteries, while the branches of the fork, on the one hand, are integral with the fixed frame carrying the bracket and support each lift arm movable vertically and by motorized means of the truck between:

a catching position, in which these arms rest on the fixed branches,

- And a lifting position, vertically away from the bending position by a distance having substantially the value of the height of a pallet without its load.

Thanks to this arrangement, the same carriage can ensure both the collection of packages and the wrapping of the pallet, without there being a break in the functional chain. The downtime, necessary for the completion of the wrapping, is of the order of 1 to 2 minutes and allows the staff, who then has no effort to provide, to recover the energy spent by loading the pallet , before starting a new loading cycle.

The wrapping operation can be launched in all areas of a warehouse having a volume sufficiently clear to allow pivoting without risk of attachment of the rotating arm carrying wrapping equipment. If, when the maximum load of the pallet is reached, the working space surrounding the pallet truck is insufficient to start the wrapping, the movement of the pallet over any distance is done quickly and effortlessly for the order picker. For this movement, as indeed for wrapping, the pallet and its load are lifted by the lift arms of the fork.

When moving the carriage, the lifting of the pallet and its load prevents its friction on the ground, while during wrapping, this lifting, at a height of at least 6 to 7 centimeters, puts the pallet at the level of space treated by the winding of the film strip and allows this band to wrap the tray and the pallet to a greater height, thus improve the fastening of the load with the pallet that carries it.

In one embodiment of the invention, each lifting arm of the fork is connected, by a chain or cable, to a common motor means adapted to communicate to the chains or cables of the two lifting arms a translational movement in the two directions controlling the vertical movements of these arms.

This mechanism is simple, inexpensive, compact and very reliable in time.

In an advantageous embodiment, the motorized trolley is that of a pallet truck whose forks are fixed to the fixed frame and whose vertical hydraulic cylinder, arranged in the frame to move the forks normally, is disconnected from these forks and is connected to the ends of chains or cables controlling the movements of the lifting arms.

Thus, the wrapper is made on the general structure of a pallet truck and with the motor means thereof, but by arranging their functions and their control means. This arrangement simplifies the construction of the wrapper, reduces the cost compared to a fully built machine, and adds, in addition to the advantages of the wrapping machine and a pallet truck, the elevation of the pallet tray compared to branches of the original fork, allowing the lowest turn of the winding of the band to come lower on the pallet.

It should be noted that it is the use of the energy source carried by the autonomous pallet truck that allows:

on the one hand, lifting the pallet with respect to its fork to bring it into the enveloping zone by the film strip,

- On the other hand, to feed the drive motor in rotation of the arm and the motor of movement of the wrapping head, - and in addition, the internal motor to this head.

Indeed, and in a preferred embodiment, the wrapping head comprises, going from upstream to downstream from a coil support vertical, pre-stretching means and means for adjusting the laying tension of the film strip, the pre-stretching means being composed of: two vertical cylinders, mounted free to rotate in the frame of the head and connected to the same electric motor, by a gear transmission communicating to the cylinder disposed downstream a circumferential speed V2 greater than that V1 communicated to the upstream cylinder, and three rollers which, rotatably mounted in a removable support frame, are interposed between the rolls for pressing against them the film coming from the reel and going to the laying tension setting means, while the tension adjusting means comprise a tension measuring roller reacting on a potentiometer controlling the feed of the electric drive motor of the two pre-stretching cylinders.

It is the particular embodiment of these means which reduces the radial space requirement and the mass of the wrapping head and makes it possible to mount the latter on a wrapping machine with a rotating arm, by providing the latter with a combination of functions until then reserved for stretch wrappers working at a fixed position.

Thus, the film strip is pre-stretched just before it is deposited, which makes it possible to use standard non-pre-stretched coils which are less expensive and which provide a greater length of strip, since they correspond to their original length multiplied by the pre-stretching coefficient.

In addition, the pre-stretching in situ gives more nerve to the band and improves the strength of its winding around the load.

As for the tension adjustment, it makes it possible to adjust the force with which the strip is pressed against the load as a function of the variations of the hollows and bumps formed by the stacking of packages. The combination of the pre-stretching with the tensioning adjustment is particularly appreciable when wrapping around the pallet plate and foot, because it guarantees the good resistance of the load with this pallet. In another embodiment, each lifting arm carried by a fork leg is movable vertically by a hydraulic cylinder which, interposed between it and the corresponding fork leg, is independent of that of the other fork and is powered by a separate hydraulic circuit from one of the two elements of a volumetric flow divider fed by the hydraulic unit of the trolley T.

This arrangement simplifies the construction of the carriage and allows the lift arms to have identical vertical strokes and that the pallet has a elevation well horizontal even though the load is not yet wrapped by the film.

Advantageously, a motion sensor is arranged on the column upright, at the height H of the personnel's hands, and is electrically connected to the cycle control means governing the power supply of the electric motor controlling the vertical displacements of the wrapping head. U on the column and the electric motor controlling the rotation of the arm, so that a complete operating cycle starts when the wrapping head U is at the height H of staff hands and stops at this position. This development of the operating cycle eliminates the risk of musculoskeletal disorders on the staff and increases the yield.

Other features and advantages will emerge from the description which follows, with reference to the appended schematic drawing, in which:

Figure 1 is an elevational side view of the apparatus when it is in the wrapping position of a loaded pallet;

Figure 2 is a perspective view of the pallet truck with phantom tracing means for lifting false branches,

Figures 3 and 4 are partial sectional views of the lifting means of the pallet, respectively, when the wrapper is in the rolling position and when in the wrapping position;

Figure 5 is a partial perspective view of the column carrying the wrapping head,

Figure 6 is a partial view in partial section and on an enlarged scale of the bracket and the arm, Figures 7 and 8 are perspective views of the components of the wrapping head,

Figure 9 is a cross-sectional view on an enlarged scale of the pre-stretching and tensioning means of the film web.

Figure 10 is a simplified perspective view of another embodiment of the false fork lifting means,

Figures 1 1 and 12 are partial sectional side views of the carriage of Figure 10, when the false forks are, respectively, in the interlocked position and in the lifting position of a loaded pallet,

Figure 13 is a schematic side view of a wrapper showing two cycles of operation thereof.

In the embodiment shown, the wrapping machine is composed of a pallet truck T on which is installed a banding equipment B. In general, and as shown in FIGS. 1 and 2, the pallet truck T is composed of a truck equipped with front wheels 2 and rear wheels 3. It also comprises a steerable and driving central wheel, not shown, connected to a electric motor 4 powered by a set of rechargeable batteries and replacements (visible Figures 3 and 4). The frame 6 of the carriage also contains a hydraulic cylinder 7 normally assigned to the vertical movements of the branches 8a of the fork 8 equipping the carriage. The jack 7 is fed by a hydraulic unit, not shown, controlled, from a control block 9 formed at the end of a drawbar arm 10, but under the control of an automaton 90, visible at the Figure 1, managing movements, cycle times and personnel safety.

The wrapping equipment B is composed of a bracket 12 whose mast 12a is carried by the frame 6 of the pallet truck and whose branch 12b is parallel to the branches 8a of the fork 8. One end of a rotary arm 13 is rotatably mounted under the free end of the branch 12b and its other end carries a column 1 1 carrying rails extending downwards.

In the embodiment shown, the slideways consist of profiles 14 on which the elements of a wrapping head U can be moved vertically by means of which one embodiment is shown in FIG. 5.

These means comprise an electric geared motor 15 which, carried by the arm 13, drives a pinion or a pulley 16 of a transmission of movements by chain or belt 17 leading to a pinion or a pulley 18 wedged on a transverse shaft 19. This shaft is rotatably mounted in bearings 20 projecting upwards from a plate 22 formed at the upper end of the profiles 14 of the column. A wheel 21 set on the shaft 19 constitutes a return member for a chain or cable whose strand 23a is coupled to the frame of the wrapping head U, while the other strand 23b is coupled to a counterweight 24, slidably mounted on the profiles 14 forming slides of the column 1 1. As shown more particularly in Figure 6, the arm 13 is integral with a vertical axis 26 which, rotatably mounted in a bearing 27 of the arm of the bracket 12b, carries a pulley 28a connected by a belt 29 to another pulley 28b. The latter is wedged on a shaft 30 itself connected, by a reduction gear train 31, to an electric motor 32. According to the invention and as shown in more detail in FIGS. 2 to 4, each of the branches 8a of the fork 8 carries a lifting arm 40 which, in the embodiment shown, is constituted by an inverted U-shaped section covering the underlying branch. This profile is connected to the branch 8a by two connecting rods 42. Each connecting rod is articulated by its lower end on a transverse axis 43 of the branch 8a and, at its upper end, on another transverse axis 44 carried by the false branch.

The axes 44 are disposed at the end of tabs 45 which, projecting downwards from the false branch, can be moved through a slot 46, arranged longitudinally in each branch 8a.

The two lifting arms 40 are connected to each other by a crossbar 47 which, fixed on their rear ends, projects upwardly to form a stop for limiting the engagement of the fork under the pallet 50 carrying the load. 52 (visible figure 1).

As in any pallet truck, the branches 8a of the fork 8 are integral with the apron 6a disposed in front of the housing of the frame 6, but in this application, the deck, normally vertically movable, is bonded, for example by welding, to the frame of the carriage. As a result, the frame 6, the apron 6a with the bracket 12 and fork legs 8a form a monolithic assembly.

The apron 6a, which is thus deprived of any possibility of vertical displacement, is disconnected from its actuating means, namely the hydraulic cylinder 7. This is used to actuate the vertical displacement means of the lifting arms 40, means comprising :

a crosspiece 33 wedged at the upper end of the rod of the jack 7,

two chains or cables 34, connected at one end to the crossmember 33 and, at the other end, to one of the lifting arms 40,

- And two wheels or return pulleys 36. As the hydraulic unit supplying the cylinder 7 is the original, its control and the vertical movements of the cylinder in both directions are controlled by the pushbuttons arranged on the control block 9 of the drawbar of the trolley.

At rest, the lifting arms 40 are in the interlocking position and rest on the branches 8a of the fork 8. They are held pressed against them by springs 48.

Thus, after having engaged the fork 8 and its arms 40 under the plate 50a of a pallet 50, as shown in FIG. 3, the operator can, without effort or displacement, control the raising of the pallet 50 on a stroke vertical adjustable L, depending on the stroke of the cylinder 7 and can be of the order of 10 cm, that is to say much greater than the normal stroke necessary to prevent the friction of the pallet on the ground during its movement by the pallet truck. FIG. 4 shows that the raising of the pallet 50 to its high lifting position brings its plate 50a to approximately 15 centimeters from the ground, and well above the lowest trajectory, represented by the broken line S, the lower edge of the film reel 60, carried by the wrapping head U, trajectory being 10 centimeters from the ground. Thanks to this, the film strip 61 unwinding from the reel can envelop both the bottom of the load 52 and the top of the pallet 50 thus ensuring a perfect connection between the two parts.

In an alternative embodiment, not shown, the cables 34 go to the free ends of the legs 8a of the fork 8 where they pass on pulleys which return them towards the deck before being hooked under the lifting arms 40. The connecting rods 42 are reversed, that is to say arranged so that when the cables 34 are subjected to traction by the cylinder 7, the arms 40 move forward at the same time as they rise. This kinematics ensures that the lifting movement of the arms 40 does not alter the minimum value of the distance D (FIG. 4) between the deck 6a and the crossbar 47.

Figures 3, 4 and 6 show that, in the form shown, the wrapping head U has a radial size R which is very small and less than the value D, when the arms 40 are in the maximum elevation position.

Despite this small size R and according to an advantageous arrangement of the invention, shown in FIGS. 7 to 9, the head U comprises, not only means for adjusting the tension 62 but also pre-stretching means 63 for the band 61. as it is unwound from the reel.

In the embodiment shown, the wrapping head U comprises a frame formed by two end plates 64 and 65 connected by tubular sleeves 66, slidably mounted on the columns 14, and by a rear stiffener 67.

Pre-stretching means 63 comprise:

two vertical cylinders 68a and 68b, having the same diameter and mounted free to rotate in the plates 64 and 65, an electric motor 69 transmitting its rotational movement to a pinion 70 meshing itself with two pinions, respectively 71 and 72 , wedged on the shafts of the cylinders 68a and 68b, these pinions having diametrical dimensions such that the downstream cylinder 68b is driven at a circumferential speed V2 greater than that V1 communicated to the upstream cylinder 68a, and for example double,

three rollers 73 mounted free to rotate in a support frame 74 and which, as shown in FIG. 9, are interposed with the cylinders 68a and 68b, so as to press the film strip 61 against substantially half the circumference of these rolls.

Figure 8 shows that the support frame 74 is independent of the frame of the head U and is removable to facilitate the introduction of the band 61 between the cylinders 68a and 68b and the rollers 73. The frame 74 is provided with vertical fingers 75 able to be engaged by vertical sliding in the slots 76 formed in the plates 64 and 65. The coil 60 is held by two rotary supports, not shown, and carried by horizontal tabs forming part of the plates 64 and 65 of the frame of the head . The voltage adjusting means comprise a roller 62 rotatably mounted in the lower plate 64 and in an upper bearing 77, visible in FIG. 9. This bearing is slidably mounted in a slot 53 of the upper plate 65 and according to a radial direction relative to the axis of rotation of the rotating arm 13. It is fixed to the end of a horizontal rod 78 pushed radially outwardly by a spring 79 bearing against a stop 80. The radial position of the bearing 77, therefore the calibration of the average voltage, is determined by the position of the adjustable stop by a nut screw system not shown.

The free end of the rod 78 carries a mass 81, non-magnetic and for example of aluminum or plastic, carrying a magnet whose visible face is of positive polarity. This magnet faces an electromagnetic sensor 82 reacting on the supply means of the electric motor 69.

Finally, the head U comprises a return roller 88 which completes the bunch formed with the roller 62 and directs the band coming from the pre-stretching station towards the zone of wrapping of the load disposed on the pallet.

When the wrapping head U is in operation and delivers a strip of film 61 which wraps around the load 52, thanks to the rotation of the arm 13, the encounter of this band with the bumps and depressions formed in the load by the irregular stacking of the packages, causes the radial displacements of the roll 62. These generate either a reduction or an increase in the flow rate of the strip, by the only adjustment of the motor feed speed 69.

It should be noted that, thanks to the use of a single electric motor 69 to drive the cylinders 68a and 68b and the presence of pinions 70, 71 and 72, ensuring a constant speed ratio between the two cylinders, the modification of the speed of rotation of the motor 69, contributing to the adjustment of the tension has no influence on the pre-stretching, since it is always carried out in the same ratio, regardless of the speed. FIG. 6 shows that the supply of the motor 19, carried by the wrapping head U to drive the pre-stretching rolls, and the supply of the geared motor 15, carried by the arm 13 to move this head vertically, are made by an electrical line 84 and a line 85 supplies the motor 32 for rotating the arm. These two lines are powered by the batteries 6 of the pallet truck T under the control of the housing 9 and under the control of the housing 90 of FIG.

The line 84 circulates in the stem mast 12a, then in the stem arm 12b, which it leaves to pass through the axial bore of the hollow shaft 26. Leaving the lower end of this hollow shaft the line 84 flows in the arm 13, where its bypass 84a feeds the geared motor 15. Above the column 11, the line 84 leaves the arm 13 to feed the motor 69 of the head U.

The dashed case 86 and disk 87 shown in this FIG. 6 are part of an arm locking device 13 unrelated to the present invention.

As a result of this simple, compact and reliable construction, the rotating arm wrapper combines two functions previously reserved for stationary installations, which are more cumbersome, and makes it possible to continuously regulate the distribution of the film strip for the adapt to the shape of the wrap of the load, while making the best use of the advantages provided by the use of standard, unstretched film strips, having immediately after pre-stretching a better shrinkage on the load. In addition the use of standard strips, pre-stretched only in the wrapper, allows the use of coils from all suppliers, and to obtain a longer winding length, for less cost.

In the embodiment shown in FIGS. 10 to 11, the elements common to the preceding embodiments will be referenced by the same number plus 100 and the new elements will be referenced from 91.

This embodiment differs from the previous ones by the means 91 implemented to move vertically upwards the lifting arms 140 between their bucking position shown in FIG. 1 1 and their lifting position of the pallet shown in FIG. FIG. 12, by the presence of sensors 96 and 97 and by a different vertical movement cycle.

Each of the arms 140 additionally comprises rods 142, hinged at their ends at 143 and 144, a single-acting hydraulic jack 91 ensuring the lifting and at least one return spring 148, tending to bring the arms 140 in the low position. The jack is hinged at 92 on the branch 108a of the fork and, on the lifting arm 140, by the hinge 144 of one of the connecting rods 142.

It is connected by a hydraulic circuit 93 to one of the elements 94a of a volumetric divider 94, itself supplied by a hydraulic unit 95. The volumetric divider 94 is, for example, composed of two gear pumps 94a which, when they are in operation, deliver exactly the same volumes in the two cylinders 91, which guarantees the same strokes of their rods, the same elevations of the arms 140 and a horizontal displacement of the pallet.

Figures 10 and 1 1 show that the divider 94 is connected by a circuit 96 to the control unit 190, which is in fact what is called a PLC, itself under the control of the housing 109 disposed on the drawbar 1 10.

With this arrangement, the two lifting arms 140 move vertically in synchronism and of the same value and can lift high loads horizontally, without these can tilt.

The single-acting cylinders can be replaced by double-acting cylinders, but when the fork is without load, the springs 148 are sufficient to bring the lift arms down and, when loaded, the mass carried by the pallet is sufficient to quickly cause the lowering of these arms, as soon as the cylinders 91 are exhausted.

This arrangement makes it possible to replace the hydraulic cylinder 7 of FIGS. 2 to 4 by a larger battery 105, as shown in FIG.

The left-hand part of FIG. 13 shows the usual operating cycle of starting a wrapping cycle of a load 52 from the bottom at a and going upwards b, then making the reverse path from b to at . This cycle, logical and widely used, has the disadvantage of requiring the staff, at each new beginning cycle, to bend to enter the band 61 and surround the foot of the load 52 on at least one turn. As this movement is repeated many times in a day's work, it causes low back pain and musculoskeletal disorders.

To remedy this, the means of the invention are controlled by the housing 190, so that the wrapping cycle is performed as shown in the right part of Figure 13, starting from a point ç located at height hands, ie at a distance of the ground H between 0.50 and 0.75 meter. Thus, starting from the level ç the cycle goes down to the point d then goes back to the high point e before descending to return and stop at the point α Thanks to this, to start a new cycle the staff does not have to bend down, since it can grab at its arms the film strip 61 to wrap around the load before launching a new cycle.

For this purpose the frame of the wrapper, and for example the mast 12a of the bracket, carries a sensor 96, which, visible Figures 10 and 13, is disposed at a distance H of the ground corresponding to the height of the staff hands. This sensor is electrically connected to the controller 190 to inform the latter of the passage of the wrapping head U. If this passage takes place in the descent phase of the head U, the controller immediately stops the wrapping cycle, leaving the staff to break the film and press it on the winding.

Preferably, during the start of each new cycle, regardless of the vertical position of the attachment point of the strip, the control and control means 90 or 190, communicate to the arm 13 a rotation on at least one turn, in electrically supplying the motor 15 without powering the motor 69 pre-stretching means of the band 61, so that the first round of tape around the pallet load is done without tension, before being wrapped by the next turn performed under pressure.

This arrangement of the cycle, allows the staff to hang the beginning of the film strip by a slight jamming on a pallet load element, for example by engagement of this end in a box or cardboard, without wasting time to ensure a positive snap, and without risk that the winding tension of the first turn disasses this first snap.

In addition, and to be certain that, during the first lifting of the lifting arms 40, 140, they have been raised to their maximum high position, at the very beginning of the cycle and before launching the rotation of the rotating arm 13, the control and control means 90 or 190 control the supply of the lifting means of the arms 40,140 until these arms are in the maximum high position detected by a level sensor 97 fixed on the apron 6a, (visible figure 13).

Thus, during the winding of the band around the load the lower turns of the winding envelop the pallet on the height necessary to obtain a good connection between the pallet and its load.

Claims

1.) Mobile wrapping machine with rotating arm for wrapping pallet loads comprising:

- a bracket (12a-12b) carried by a carriage T equipped with a fork (8) for pallet (35),

an upper horizontal arm (13) mounted free to rotate under the end of this bracket and around a vertical axis,

- motorized means (27 to 32) for rotating the arm (13), and at least one vertical column (1 1) under the free end of the arm (13) and on the slides (14) of which can slide the frame of a wrapping head U, characterized in that the carriage T is provided with means (2 to 4) for translational movement in the horizontal plane whose electric motor (4) is powered by rechargeable batteries ( 5), while the branches (8a-8b) of the fork (8), on the one hand, are integral with the fixed frame (6) carrying the bracket (12a-12b) and, on the other hand, support arms lifting means (40, 140) movable vertically by motorized means (7, 91) of the carriage between:

- a bending position, in which these lifting arms (40, 140) rest on the fixed legs (8a-8b) of the fork (8), - and a lifting position, vertically remote from the bending position by a distance L substantially having the value of the height of a pallet (50) without its load.

2.) Mobile wrapper with rotating arm according to claim 1 characterized in that each of the lifting arms (40, 140) is constituted by a U-shaped metal section returned to the underlying branch (8a-8b), this section being connected at the branch by at least two connecting rods (42), each connecting rod being articulated on a transverse axis (43) of the fork (8) and on a transverse axis (44) of the arm (40, 140).

3.) Mobile wrapper with rotating arm according to claim 1 characterized in that each lifting arm (40) is connected by a chain or cable (34) to a common motor means (7) adapted to communicate to these chains or cables (34) a translational movement in both directions controlling the vertical displacements of these arms.

4.) mobile wrapper with rotating arm according to claim 1 characterized in that the motorized carriage is that of a pallet truck T whose fork legs (8a-8b) are fixed to the deck (6a) of the frame (6) and the vertical cylinder (7), disposed in the frame (6) to move the fork (8) normally, is disconnected from these branches (8a, 8b) and is connected to the ends of chains or cables (34) controlling the movements of the arms of lifting (40).

5.) mobile wrapper with rotating arm according to claim 1 characterized in that the wrapping head U comprises, going from upstream to downstream from a vertical coil carrier (60), means of pre drawing (63) and means (62) for adjusting the laying tension of the film strip (61), the pre-stretching means (63) being composed of: two vertical cylinders (68a and 68b), mounted free in rotation in the chassis (64, 65, 66) of the head and connected to the same electric motor (69), by a gear transmission (70 to 72) communicating with the cylinder (68b) disposed downstream a circumferential speed V2 greater than that V1 communicated to the upstream cylinder (68a), and three rollers (73) which, rotatably mounted in a removable support frame (74), are interposed between the cylinders (68a, 68b) to press against them the film (61) from the spool (60) to the tension setting means (62), while said voltage adjusting means (62) comprises a voltage measuring roller (62) responsive to means (81, 82) controlling the supply of the electric motor (69) for driving the two cylinders (68a, 68b). ) pre-stretching.

6.) Mobile wrapper with rotating arm according to claims 1, 4 and 5 taken together, characterized in that the shaft (26), by which the rotating arm (13) is pivotally mounted on the arm (12b) of the stem (12), is hollow and serves for the passage of a power line (84) from the batteries (5) of the pallet truck to the motor (15) of vertical displacement of the wrapping head U and the motor (69) of the means of pre -drawing.

7.) movable arm wrapper with rotating arm according to claim 1, characterized in that each lifting arm (140) is moved vertically by a hydraulic cylinder (91) which, interposed between it and the corresponding fork leg (108a), is independent of that of the other fork and is fed by a separate hydraulic circuit (93) from one of the two elements (94a) of a flow divider (94) fed by the hydraulic power unit (95) of the truck T .

8.) Mobile wrapper with rotating arm according to claim 1, characterized in that a movement sensor (96) is arranged on the upright (12a) of the bracket, at the height H of the staff hands, and is

75 electrically connected to the cycle control means (90) governing the supply of the electric motor (15) controlling the vertical displacements of the wrapping head U on the column (11) and the electric motor (32) controlling the rotation of the arm (13), so that a complete operating cycle stops and starts when the wrapping head U

80 is at the height H of the hands of the staff.

9.) Mobile wrapper with rotating arm according to claim 1, characterized in that it also comprises a sensor (97) which, arranged on the apron (6a) to detect if the arms are in the maximum high position, is electrically connected to cycle control means (90, 190) governing the

Operation of the lifting means of the arms (40, 140) for, at the beginning of the cycle and before rotation of the arm (13) carrying the wrapping head U, and if these arms (40, 140) are not in position high, control the feeding of their lifting means until they reach this high position.

10.) Mobile wrapper with rotating arm according to claims 1 and 5

90 taken together characterized in that, in the start-up phase, the automaton constituting the control and control means (90, 190) communicates to the arm (13) a rotation on at least one revolution without supplying the motor (69) with means for pre-stretching the web (61) so that the first web turn around the pallet load is carried out without tension.