WO1999001347A1

WO1999001347A1 - Portable device for wrapping loads in extensible prestretched film

Info

Publication number: WO1999001347A1
Application number: PCT/EP1998/003746
Authority: WO
Inventors: Pierpaolo Battista
Original assignee: C.B. S.P.A.
Priority date: 1997-07-02
Filing date: 1998-06-19
Publication date: 1999-01-14
Also published as: AU8627998A; ITBO970407A1; ITBO970407A0; IT1293226B1

Abstract

Portable device for wrapping loads in an extensible prestretched film, comprising a frame (1; 5), comprising a head wall (101; 50), a base wall (201; 51) and at least a lateral wall (301; 56), capable of supporting rotatably by their ends in a vertical and mutually parallel arrangement one small reel (10) of extensible film (20) and at least one pair of rollers (3, 2; 6, 7), around which rollers the film drawn from the said reel (10) is passed in succession, the rollers (3, 2; 6, 7) being connected to driving means by means of appropriated transmission means (204, 202, 102, 103; 226, 227), the peripheral speed of the said rollers being increasing in the direction of unwinding of the film.

Description

Portable device for wrapping loads in extensible prestretched film

DESCRIPTION

For wrapping loads, the use of extensible film which is stretched before being wrapped around the load is known. For carrying out this procedure, there are known automatic machines in which the load may remain stationary or may be rotated about a vertical axis. The head end of the film is fixed to the load and unwound from a reel carried by a film delivering and prestretching unit, which in machines of the first type is rotated around the load, while in machines of the second type is stationary. In both machines, since the width of the film used is usually less than the height of the load to be wrapped, the unit delivering the prestretched film is raised and lowered during the wrapping operation in order to wrap the full height of the load helically, the turns of the helix overlapping each other to form a coherent and very strong binding by which the load is securely bound to, for instance, the pallet supporting it, thus making it secure for subsequent handling by fork-lift trucks and for transportation. The film is usually prestretched lengthwise by passing it through a series of rollers rotating at increasing speeds. In certain cases the film is also prestretched crosswise by passing it through grooved rollers partly intermeshing in a comb-like manner. The purpose of prestretching the film is to achieve a taut wrapping of the load so that it is held delicately, and also to make the wrapping economical, given that the prestretching itself increases the dimensions of the film drawn from the reel, often by more than 100%.

The cost of the machines described above does not justify their purchase by users who would only require them very periodically, and in any case such machines cannot be used where there are space problems, for example in small craft-based businesses. The wrapping cycle performed by the above machines cannot be performed in extemporaneous situations in which the machines cannot be set up, or there is no electrical power supply to run them, for example on farms .

For wrapping palletized loads or other products in extensible prestretched film, the invention provides a device of moderate cost, limited dimensions and weight hence portable, that can be easily operated by one person and can carry its own autonomous power source, e.g. rechargeable batteries, thus enabling it to be used even without direct connection to mains electricity.

The object of the present invention is therefore a portable device for wrapping loads in extensible prestretched film, comprising a frame rotatably supporting in a vertical and mutually parallel arrangement one small reel of extensible film and at least one pair of rollers of known configuration, around which the film drawn from the said reel is passed in succession, the rollers being connected to driving means by means of appropriated transmission means, the peripheral speed of the said rollers being increasing in the direction of unwinding of the film.

Another object of the present invention is a device as referred to above, in which are provided one or more idle rollers, placed upstream and/or downstream of the said driven rollers; the said idle rollers can be swingingly mounted on the said frame.

Advantageously, one of the said rollers, driven or idle, is movable in respect to the frame, along a direction perpendicular to the direcion of unwinding of the film, being provided on the said frame means for the detection of the motion of the said roller, said means being coupled to means for the control of the speed of the driven rollers .

Further object of the present invention is a supporting structure for the above described device, comprising a truck mounted on pivoting wheels, a portal positioned on the said truck, the device being connected to a member sliding on a pillar of the said portal, and coupled to a counterweight member, provided with locking means, sliding on the other pillar of the said portal.

Further features and advantages of the device of the present invention, will become evindent in the following description of some preferred embodiments illustrated purely by way of non-restrictive example in the figures of the attached drawings, in which:

Fig. 1 shows the device according to a first embodiment of the invention in perspective and in the condition of use;

Fig. 2 is a perspective drawing of the device of Fig. 1, showing the means for driving the film prestretching rollers; Fig. 3 is a transverse cross-sectional view of a second embodiment of the device according to the invention;

Fig. 4 is an elevational side view of the device of the Fig. 3; Fig. 5 is a longitudinal cross-section of the device of the Fig. 3;

Fig. 6 is an elevational side view of the device according to the present invention mounted on a supporting structure; Fig. 7 is a top plane view of the structure of the Fig. 6. In the figures 1 and 2 it can be seen that the device comprises a support frame 1 made out of, for example, aluminium alloy sheet of suitable thickness to keep the weight down and yet at the same time to give the necessary mechanical strength. The frame 1 includes two small parallel walls, a head wall and a base wall 101 and 201, joined by an upright wall 301. The base wall 201 in plan view is approximately rectangular while the head wall 101 lacks one end portion where it carries a centering disc 12 whose spindle 11 rotates in a bracket 421. The latter has an arm with a lengthwise slot 401 to allow it to be guided and fixed to the upright wall 301 by means of a thumbscrew 411. The disc 12 sits on the end of the cardboard core of a reel 10 of extensible film 20, which may be of the type known in the trade by the letters LLDPE, of limited width, e.g. of the order of 20-60 cm, and the opposite end of the same reel 10 rests via its cardboard core on the centering disc 13 fixed to the base wall 201 of the frame 1. The discs 12 and 13 support the reel 10 at right angles to the walls 101, 201 and provide friction in order that the film can be unwound from the reel only if pulled. To replace the reel 10 when finished, the screw 411 is slackened and the bracket 421 raised together with its disc 12.

The film 20 unwound from the reel 10 is fed around the following rollers, all of which are supported rotatably at their ends by the walls 101, 201 of the frame 1 and all parallel to each other and to the said reel 10 and preferably all structurally hollow to keep the weight down: - an optional idle roller 111, of limited diameter; and a first roller 3 and a second roller 2, separated from each other by a suitable distance and covered externally with an elastomeric material preferably having alternately raised and sunken lengthwise lines. These rollers are driven so as to draw the film which is fed around them and their peripheral speed increases such that the free portion of film located between the rollers is subjected to the necessary lengthwise prestretching; and an optional idle roller 121 of limited diameter .

The idle rollers 111 and 121 are for the purpose of ensuring that the film contacts a sufficiently large portion of the circumference of the prestretching rollers 3 and 2.

In the present example, the prestretching rollers 3 and 2 differ in diameter by a ratio of 1:2, so that they can be driven at the same angular velocity. In Figure 2 it can be seen that the spindles of the rollers 3 and 2 each project at one end from the wall 201, and gear wheels of equal diameter 102, 103 are fixed to these spindles. The gear wheels may be made from some suitable plastic material, for example, and are in mesh with one another. Fixed to the same spindle of the roller 2 which turns with a greater peripheral speed is a ring gear 202 with which meshes a perpendicular pinion 204 fixed to the output shaft of a small motor gearbox assembly 4. The latter is mounted on a small bracket 104 attached to the wall 201 and may for example be of the type used in small drills or portable power screwdrivers: it is powered by a small d.c. electric motor that can run off a low-voltage source such as a rechargeable electric battery 304 mounted in its own housing 314 on the same wall 201. The edges of the wall 201, or at least the long edges, are suitably bent out as indicated at 221 and 231, both to strengthen the wall and to give it a boxlike form useful for containing the above mentioned drive, which will be hidden and protected by a cover (not shown) . The bracket 104 of the motor/gearbox assembly may advantageously also be fixed to a small cross member 211 fixed to the neighboring edge 231 of the wall 201.

Part of the upright wall 301 of the frame 1, as indicated at 311, is cut through where it meets the end walls and, alongside the large-diameter roller 2, is bent out, and, at the end nearest the head wall 101, is fitted with a handle 501 preferably with a grip 511 of sufficiently anatomical design and generally parallel to the axis of the rollers. A handle 601 is fixed to the edge 221 of the wall 201, to the side of the reel 10, and its grip 611, of preferably anatomical design, is preferably perpendicular to the said grip 511 of the said handle 501. The grips 501 and 601 are in an opposing and oblique arrangement relative to the frame

1 in order to permit easier control and orientation of the device.

To complete the device in the simplified version illustrated in the drawings, a button 521 is provided to start the motor/gearbox assembly 4, and may be located, for example, on the handle 501 in a position where it can conveniently be operated by the thumb of the hand holding the said grip. The device described has a weight that may vary between 1.5 and 2.5 kg, preferably not greater than 2 kg, so that it can be held and controlled without fatiguing any operator.

The device as thus devised works in a simple and obvious manner. The end of the film coming off the device is fixed by any appropriate means to the pallet or load 30 that is to be bound. The operator grasps the grips 511 and 611 with two hands, supports the device such that the rollers are vertical, as in Figure 1, and pushes the button 521 to start the motor/gearbox assembly 4: this turns the prestretching rollers 3 and

2 which draw film from the reel 10 and prestretch it lengthwise by the intended amount. The operator moves around the load 30, keeping the prestretched film in tension as it leaves the device still with its elastic memory so that it binds the load under tension. As he or she moves around the load, the operator will gradually move the device upwards and then downwards to effect the desired helical wrapping, at the end of which the operator removes his or her thumb from the button 521 to stop the device, and will then cut the tail end of the film with some suitable means and fix it to the finished wrapping by making use of the inherently adhesive nature of the extensible film.

In the Fig. 3 is drawn, cross section, a second embodiment of the present invention. With the numeral 5 is designated the boxlike frame of the device, having an head wall 50, a base wall 51 and at least a lateral wall 56. Inside the said frame are placed two rollers 6 and 7, which axis 106 and 107 are respectively coupled, by means of appropriated transmission means 226 and 227, with the driving means 206, 207. Upstream and downstream of the said rollers 6 and 7, in respect to the dispensing of the film 20 by the reel 10, located on the cantilever arm 705, the idle rollers 115, 125, 135, 305 and 205 are placed. The idle rollers 115, 125 and 135 are rotatably mounted on the cover 105, hinged to the frame 5 by means of the hinges 155 and swinging in respect to the same. The sliding bolt 145 allows the locking of the cover 105 in respect to the head wall 50 of the frame 5. The idle rollers 305 and 205 are instead mounted rotatably in respect to the head and the base walls 50 and 51, the roller 305 has its axis inserted in a slot 405. On the lateral wall 56 the handles 505 and 605 can be seen.

In Fig. 4 is drawn the device of the Fig. 3 in side elevational view. The same numerals correspond to the same parts. In the figure it can be seen the kind of driving provided to the rollers 6 and 7 by means of the motors 206 and 207, powered by the respective batteries 306, 307, located in the respective housings 316, 317. Further, it is visible the guiding block 325 placed at the end of the axis 315 of the roller 305, which block is provided at its top with an actuator 335. In the figure are further illustrated the fixed wheels 905 and the pivoting wheel 805, both mounted on the base wall 51 of the frame 5 of the device.

In figure 5 is drawn the device of the Fig. 3 in longitudinal section. As results in the figure, the block 325 carrying the actuator 335 is connected by means of an helical spring 355 to a limb 52 projecting from the head wall 50; likewise, at the other end of the axis 315 of the roller 305, another block 325 is connected by a spring 355 to a limb 55 projecting from the base wall 51. The actuator 335 can contact the pad 54 of the detector 53, for instance a force detector, when the increasing of the tension of the film causes the displacement of the axis 315 of the roller 305 along the slot 405. In the figure is . further shown the cover 105 in closed position as well as in open position (dotted line) .

The operation of the device above described is appearent according to the following. Similarly to all that has been explained about the first embodiment of the invention, shown in the Figg. 1 and 2, also in this case the device of the invention allows the prestretched unwinding of the film 20 from the reel 10. In the case drawn in the Figg. from 3 to 5, the said operation is carried out using two rollers having substantially the same diameter, driven in an indipendent manner one from another. It is particularly useful the arrangement of the idle rollers 115, 125 and 135 on the cover 105 swinging in respect of the frame 5 of the device; in fact, the user, when charging the film 20 in the device, must only move the end of the film 20 from the reel 10 to the idle roller 205 with a single passage around the idle roller 305. Then, after closing the cover 105, the above mentioned rollers 115, 125 and 135 will be inserted in the respective positions allowing the optimum contact between the surface of the film and that of the driven rollers, and by this way improving the stretching conditions . Another important feature of the present embodiment is the possibility of controlling the rotating speed of the driven rollers according to the tension generated on the film near its exit from the device. In fact, during wrapping of loads having for instance parallelepipedal shape, it is known that the tension incraeses at the edges of such a load. This problem, together with the prestretching, can cause damages to the film. In the same way, the variations in the speed of the operator moving around the load to be wrapped can affect the continuity of the film.

At this end, as it results in the Fig. 5, the idle roller 305 is mounted with its axis inserted at each end in one block 325, rotatable thanks to the bearing means 345, and the said block is connected, by means of a spring 355 to a limb, 52 and 56 respectively, of the head wall and of the base wall. The block 325 is provided at its top, toward the head wall 50, with an actuator 335 that is able to cooperate with the pad 54 of the detector 53. When the actuator 335 contacts the pad 54, then the detector 53 sends its corresponding signal to the driving means 206, 207 of the driven rollers 6 and 7.

Advantageously, in the embodiment shown in Figg. from 3 to 5 are provided wheels, connected to the base wall 51; there are due wheels 905 having fixed axis and a wheel 805 having pivoting axis. Thanks to these wheels, the beginning of the wrapping operation, that starts always from the bottom to the top of the load, became much more easier, and the same wrapping will be carried out in a more regular and accurate way. In Fig. 6 is shown a supporting structure for the device according to the present invention. The said structure comprise a truck 8 mounted on pivoting wheels 208, and provided with handling bars 108; on the truck is mounted a portal 9. On the pillar 109 of the portal 9 is placed, connected to member 119 sliding along the pillar 109, the device according to the present invention; particularly, in the figure is shown a device of the kind of that shown in Figg. 3 to 5. On the other pillar 209 is slidably inserted a counterweight member 219, which is connected by means of the cable 309 and the pulley 409, to the member 119. The member 219 is provided with locking means, that is the lever 239 which operates the screw bolt 249. In Fig. 7 the supporting structure and the device are represented in plane view, during the wrapping operation of a load 30; in the figure can be seen the connection between the frame 5 of the device of the invention and the cantilever arm 139 of the member 119.

Although the device according to the invention has been designed essentially to be a portable one, and being therefore usable by direct handling of the operator, there are also some cases in which it could be convenient to have an available supporting structure. Such a structure can allow the wrapping of palletized loads even of great dimension without a big effort, such as can be useful, from another hand, to have the said structure if the wrapping operation shall be repeated many times. Operationally, after having placed the device on the member 119 sliding on the pillar 109, the operator begins to wrap the film around the load. At every turn, the height of the device can be changed lowering the counterweight member 219 and locking the same at a certain position with the locking means 239, 249.

The device according to the present invention and the supporting structure allow the wrapping with film of loads even in firm situations in which till now the said operation resulted extremely difficult from one hand and expensive from the other hand.

The following modifications may be made to the device as described: - means may be mounted on the frame, e.g. downstream of the rollers, for cutting the film at the end of the load wrapping cycle. These means may for example comprise a saw-toothed blade, normally retracted within a spring-loaded guard against which the film can be pressed when the device is orientated in a particular way. The pressure of the film on the said spring-loaded guard can cause it to retract and can expose the saw-toothed blade which will then cut the film. This means is not illustrated because it is known in automatic machines for wrapping products in film; - the motor could be direct-current or alternating-current and could as an alternative be powered via an electric lead connected to a supply situated, for example, on a suitable fixed or rotating mounting located above the load to be wrapped; - if the device is used for wrapping non- palletized loads and if the head end of the wrapping cannot be fixed to the load, use may be made of a means suitable for this purpose, positioned on or near the load to be bound; and - in combination with or as an alternative to the use of rollers of the type described for prestretching the film lengthwise, rollers may be used to carry out the transverse prestretching of the said film, the film being selected so as to have characteristics suitable for the purpose.

Claims

1. Portable device for wrapping loads in an extensible prestretched film, comprising a frame (1; 5), comprising a head wall (101; 50), a base wall (201; 51) and at least a lateral wall (301; 56), capable of supporting rotatably by their ends in a vertical and mutually parallel arrangement one small reel (10) of extensible film (20) and at least one pair of rollers (3, 2; 6, 7), around which rollers the film drawn from the said reel (10) is passed in succession, the rollers (3, 2; 6, 7) being connected to driving means by means of appropriated transmission means (204, 202, 102, 103; 226, 227), the peripheral speed of the said rollers being increasing in the direction of unwinding of the film.

2. Device according to Claim 1, in which the prestretching rollers (3, 2) have increasing diameters, for example with a ratio of 1:2, and carry, fixed at one end, gearwheels (103, 102), of for example equal diameter, that mesh together, the end of the larger-diameter roller having fixed to it a ring gear

(202) with which there meshes a pinion (204) fixed to the output shaft of a small motor/gearbox assembly (4) comprising an electric motor and fixed to that end of the frame (1) which supports the said rollers (3, 2) .

3. Device according to Claim 1, characterized in that the said rollers (6, 7) have the same diameter and are driven with driving means (206, 207) indipendent one from another.

4. Device according to Claim 1, characterized in that upstream and down stream of the said driven rollers (3, 2; 6, 7) are inserted two or more idle rollers (111, 121; 115, 125, 135, 305, 205) having the axis parallel to the axis of the said driven rollers (3, 2; 6, 7), one of the said rollers, driven or idle, being movable in respect of the frame (1; 5) along a direction perpendicular to the direction of unwinding of the film, and in which on the said frame (1; 5) are provided means for the detection (53) of the motion of the said roller, placed near and end of the the said roller, said detection means (53) being coupled with the driving means (4; 206, 207) of the driven rollers (3, 2; 6, 7) .

5. Device according to Claim 4, in which the said roller movable in respect of the frame (5) is an idle roller (305) placed downstream of the said driven rollers (6, 7 ) .

6. Device according to claim 4, in which said detection means comprise a force detector (53) , operated by an actuator (335) placed at an end of the axis of the said roller (305) .

7. Device according to Claim 1, in which the driven prestretching rollers (3, 2; 6, 7) are characterized in that they have a relatively soft and suitably roughened outer lateral mantle with, for example, alternately raised and sunken longitudinal scoring, such that it has a high coefficient of friction with the film passing around the said rollers.

8. Device according to Claim 1, characterized in that the frame (1; 5) is provided with at least two handles, a first handle (501; 605) being placed on the lateral wall (301; 56) near the head wall (101; 50) having its grip axis parallel to the axis of the rollers, the second handle (601; 505) being placed near the base wall (201; 51) having its grip axis perpendicular to the axis of the rollers.

9. Device according to Claim 1, in which the base wall (201; 51)- or head wall (101; 50)- of the frame

(1; 5) carrying the transmission and/or the driving means of the prestretching rollers (3, 2; 6, 7), is of boxlike construction and is fitted with a cover for containing and protecting these means.

10. Device according to Claim 1, in which the reel (10) of extensible film(20) rests via one end of its core on a centering disc (13) fixed, for example, to the base wall (201) of the frame (1) , while the head wall (101) of the same frame is open in the region of the other end of the said reel (10), with the said end of the core being fitted to a centering disc (12) supported rotatably by a right-angled bracket (421) which is guided parallel to the said reel and fastened by appropriate means (411) to the upright wall (301) of the said frame (1), the arrangement being such that by moving the said bracket it is possible to replace the reel when it is emptied.

11. Device according to Claim 1, characterized in that it can be provided with a removable housing in order to protect the various rollers.

12. Device according to Claim 1, in which the driving means for driving the film prestretching rollers (3, 2;

6, 7) are powered by a rechargeable electric battery

(304; 306, 307) mounted in its own housing (314; 316, 317) .

13. Device according to Claim 1, in which the driving means (4; 206, 207) of the prestretching rollers (3, 2; 6, 7) is controlled via a button (521) positioned, for example, in the vicinity of one of the handles (501, 601; 605, 505) of the said device, in order to enable it to be operated by a finger or thumb of the hand that is holding the grip (511) of this handle (501) .

14. Device according to claim 1, characterized in that it can be equipped, downstream of the prestretching rollers (3, 2; 6, 7) around which the stretched film is passed, with known means for the transverse incision and/or cutting of the film when the device is orientated in the appropriate way to cause the film itself to press against these cutting means, at the end of each wrapping cycle .

15. Device according Claim 1, characterized in that the extensible film employed and the stretching rollers employed may be such as to carry out, as an alternative to or in combination with the lengthwise stretching, a transverse stretching of the same extensible film.

16. Device according to Claim 1, characterized in that it can be equipped with supplementary means to be located laterally and at the base of the load that is to be bound, to which means the head end of the wrapping film can be temporarily attached when this end cannot be fixed to the pallet or load to be wrapped.

17. Device according to Claim 1, in which two or more wheels (805, 905) having fixed or pivoting axis, are connected to the base wall (51) of the frame (5) .

18. Device according to Claim 4, in which one or more idle rollers (115, 125, 135) are mounted swinging in respect of the frame (5) , hinged to the head wall (50) or to the base wall (51) .

19. Device according to Claim 18, in which two or more idle rollers (115, 125, 135) are mounted on a cover (105) swinging in respect of the frame (5), hinged to the base wall (51) .

20. Supporting structure for the device according to Claim 1, comprising a truck (8) mounted on pivoting wheels (208) and provided with steering means (108), a portal (9) placed on the said truck (8), the said device being connected to a member (119) slidably movable on a pillar (109) of the said portal (9), coupled to a counterweight member (219) , provided with locking means (239, 249), sliding on the other pillar (209 of the portal (9) .