GB2192853A

GB2192853A - Pallet wrapping apparatus

Info

Publication number: GB2192853A
Application number: GB08624758A
Authority: GB
Inventors: Soria Angel Ortego
Original assignee: Inpropack S L
Current assignee: Inpropack S L
Priority date: 1986-07-24
Filing date: 1986-10-15
Publication date: 1988-01-27
Also published as: ES2000561A6; GB8624758D0

Abstract

This invention refers to an automatic pallet wrapping machine, where loaded pallets are located on a rotary platform 2 which, as they are turned, have a first plastic film helically wrapped around over their periphery at the same time as a second cover plastic film is placed over the top of the loaded pallet. The first film 11 is carried by a vertically displaceable carriage 10 and the platform mounts a clamp 17 for gripping the leading end of the film which is formed after heat-sealing and severing of the trailing end of the previously-wrapped pallet. The second cover film is drawn over the pallet load from a reel 28 by means of slidably-displaceable transverse carriage 29 (Fig. 3) mounting film- gripping clamps. The machine operation is fully automatic. <IMAGE>

Description

SPECIFICATION Pallet wrapping apparatus This invention relates to pallet wrapping apparatus and a method of applying a wrapping to a pallet.

Wrapping machines are known which have a rotary platform driven by an associated motor group and on which a pallet is placed. A feed reel of plastic film is suitably installed on a carriage which can be moved vertically up and down a column located beside the rotary platform so that, by means of combined rotary movements of the pallet and vertical displacement of the feed reel a helical wrap of plastic film around the pallet is achieved.

This type of machine has fundamental problems insofar as the high level of manual intervention required for its operation. In more specific terms, manual operation is required in order to secure the end of the plastic film; to press a button to start the operation of the machine; to stop the unit once the wrapping operation as such is completed, and to effect cutting of the plastic band and its final securement by appropriate means.

In many cases, it is also necessary to cover the upper end of the pallet with a further plastic sheet, and this operation has normally been done entirely manually. While mechanisms do exist for the automation of this step their design makes them expensive, they occupy a large volume, are heavy and, in operation, consume excessive amounts of energy.

In specific terms, machines are well known which have an upper overhanging head over which is suspended the reel supplying the plastic band which is intended to create an upper cover for the pallet. This reel is moved sideways and alternately over the pallet, letting the plastic strip drop as it passes. This makes it necessary to support and move a considerable weight, whose intermittent and alternating movement creates significant problems from the point of view of inertia forces, which slows the operation and diminishes the production of the machine.

In addition, these types of machines use cutting blades to make the abovementioned "covers" which, if they are to be effective, require extreme structural complexity and, therefore, also involve an increased cost, not only for installation but for maintenance as well.

According to one aspect of this invention, there is provided apparatus for applying a wrapping of sheet material to a pallet, said apparatus comprising a platform for supporting a pallet and being mounted for rotation about a rotation axis, drive means for rotating said platform, sheet material dispensing means disposed beside said platform and being mounted for movement in a direction generally parallel to said rotation axis, drive means for moving said sheet material dispensing means between a position adjacent the base of said pallet to a position adjacent the opposed end of said pallet and, clamp means mounted on said platform for rotation therewith and being operable to clamp the end region of a length of sheet dispensed by said dispenser.

According to another aspect of this invention there is provided a method of applying wrapping to a pallet, said method comprising locating said pallet on a rotatable platform, having a clamp associated therewith; supplying sheet material from a dispenser to said clamp and operating said clamp to clamp the sheet material; rotating said platform whilst moving said dispenser in a direction generally parallel to the axis of rotation of said platform, thereby helically to wrap the pallet; severing said sheet material and then securing the severed end.

By way of example only, one specific embodiment of automative pallet wrapping machine will now be described in detail, reference being made to the accompanying drawings in which: Figure 1 shows a diagrammatic side view of the automatic pallet wrapping machine; Figure 2 shows a front view of the machine of Figure 1; Figure 3 shows a top plan view of the machine, with the upper horizontal frame removed for clarity; and Figure 4 shows a top plan view of the machine with the horizontal frame.

Referring to the drawings, it can be seen that the automatic pallet wrapping machine is supported on a base frame 1 which incorporates a rotary platform 2 which has a series of motor driven rollers 3 for moving pallets 4 which are placed on the platform for wrapping. The base frame also has coupled to it two conveyor chains (not shown) for supplying and removing pallets from the platform before and after wrapping respectively.

The rollers 3 are driven by a motor-reduction group 5 installed inside the frame 1 which transmits movement to the rollers 3 through the transmission unit 6. The rotary platform has a catch designed to stop the platform at the end of each cycle in the correct position for its motor-driven rollers to remove the pallet.

Each pallet 4 is delivered to the machine by means of the supply conveyor chain (not shown) and is moved by its rollers 3 until it is in the correct position on the platform 2. The correct position is detected, for example by a photo-electric cell 7 and at this stage the rollers are stopped.

The movement of pallets to and from the platform is controlled automatically by means of suitable detectors (not shown) such as photoelectric cells, stroke limiters, or similar devices, in a manner known to those skilled in the art.

The machine has a motor-reduction group 8 for rotating the platform 2 which is designed to allow gradual start and stop of the platform to smooth the movement and prevent tugging of the sheet material. A column 9 supports for sliding movement a vertically movable lift carriage 10 which carries an associated reel 11 of plastic film. The carriage 10 slides on guides 12 and is driven by the motor-reduction group 13 installed at the upper end of the column 9 (see Figure 3). From the upper end of column 9 arm 14 emerges forwardly and carries a tamper 15 which can be moved vertically under the influence of the air-operated piston 16.

At one point on the edge of the rotary platform 2, there is a clamp 17 for securing the end 18 ofthe plastic film which is fed from the reel 11. The clamp 17 is driven by a pneumatic ram 19 via a suitable transmission, to open and close its jaws.

After gripping the free end 18 of the plastic film, the clamp draws the film from the reel 11 as the clamp 17 rotates with the platform 2 and the wrapping operation is begun.

In more specific terms, the machine is programmed to cause the rotary platform to give one and a half turns before the upward movement of the carriage 10, is initiated. The carriage 10 contains the abovementioned reel 11 so that the film is overlapped on itself and automatically fixed in place. The jaws of the threading clamp 17 can then be opened and upward movement of carriage 10 is begun so that from this point on, the helical wrap is provided in the upward direction. When the plastic film reaches the upper end of the pallet 4, the carriage 10 is kept still and the platform is rotated through one and a half turns.

The downward movement of the carriage 10, then begins, so providing a helical wrap in the opposite direction until reaching the bottom end of the pallet.

At this point a pneumatic cylinder 20 moves an arm 21 supporting a roller 22 which presses the plastic film against the periphery of the wrapped pallet, at the same time as the clamp 17 is once more closed. The roller 22 projects over one of its generatrices near the welding and cutting zone, so as to ensure that the plastic band is completely secured during these operations. Immediately following this, a welding device 23 is brought into operation to secure the film. The device 23 incorporates electric resistance heaters and appropriate thermostatic controls, which in use approach the pallet and weld the end of the film to the next inner layer of the wrap. At the same time, a cutting device 24 also in the form of an electrical resistance wire, finally cuts the film.One of the cut edges is fixed to the pallet 4 by virtue of the action of the weld mechanism 23, while the other end is moored by means of the clamp 17 so as to be ready to start a new operating cycle for the machine on another pallet.

The reel 11 which supplies the plastic film for the lateral wrapping incorporates on its shaft an electromagnetic brake 25 which provides a suitable degree of tension to the film as it is wrapped on the pallet 4. This brake mechanism inludes a jockey wheel 26 which rides on the surface of the reel and senses the diameter of the reel and adjusts the brake accordingly.

Obviously the larger the reel diameter, the greater the braking torque applied.

For the automatic supply of lengths of plastic film for sealing the upper portion of the pallet, the machine incorporates, at the upper end of its column 9 a generally horizontal guide frame 27, usually rectangular in shape, on which a second reel 28 of plastic film is fitted in order to provide the covering sections for the upper end of each pallet. An automatically operated dispenser carriage 29 is slidably movable in a horizontal plane over the pallet and provided with clamps 30 which are activated by pnuematic cylinders 31 and designed to secure the edge of the plastic film supplied by the reel 28.

The carriage 29 is moved along the guide frame 27 towards the end region housing the reel 28 and then grips the free end of the plastic film with its clamps 30. The carriage 29 then moves away from the reel 28 so as to draw the film, within an imaginary horizontal plane over the pallet 4 as shown in complete detail in Figure 1, where the stretched strip is referenced 32. Once the plastic film has been thus extended, it is cut by the cutting devices 33 which, for preference, will consist of a thermal electrical resistance which moves against a base under the action of a pneumatic ram 34. The dispenser carriage 29 is then returned to its original position in preparation for a further cycle.The supply of the plastic film from the reel 28 is achieved with the help of a feed device 35 which suitably guides the film so that it is moved downward vertically towards the area where the cutting mechanisms are housed.

In the centre of the guide frame 1 is the tamper 15 which is designed to press the film 32 against the upper end face of the pallet 4.

The unit which is made up of the guideframe 27 and its associated components, including the tamper 1 5 can be moved vertically on the support column 9 so as to regulate the level of the unit in accordance with the height ofthe pallets. The frame 27 is supported by reinforcing guys or ties 36 because it is in a cantilevered position.

The rotation shaft of the second supply reel 28 is associated with a motor 37 which rotates during supply so as to facilitate supply, and by an inertia brake 38 which is operable to lock the reel at the critical moment when it must be stopped.

Movement of the dispenser carriage 29, along the frame 27 is provided by a motorreduction group 39, which is controlled by the machine's governor circuit, and by means of stroke limiters suitably installed for this purpose.

In order to start the operating cycle of this upper section of the machine, there- is provision for a photoelectric cell 40 which detects the pallet 4 as well as the free end of the film from reel 28 with sufficient drop, as shown in Figure 2, to ensure a reasonable overlap on the side wall of the pallet when the cut film is placed in position as shown in Figure 1.

The guide frame 27 together with the tamper 15, can be moved vertically on column 9 by means of the said motor 13, using the frame guides 12 which support the lift carriage 10, which carries the lower reel 11 for the lateral wrapping operation.

The column 9 contains an electrical control panel 41, for general control, as well as a control panel 42 for the operation of the upper dispenser, whose function must be independent of that of the rest of the machine, given that there will be cases when only the lateral wrapping of the pallet is required.

In operation, when a pallet 4 reaches the wrapping machine's rotary platform 2 and its presence is detected by the photoelectric cell 40, the dispenser carriage 29 clamps the free end of the plastic film and the carriage is then moved, drawing the band until it is placed in overlapped fashion over the upper end of the pallet, and the length required for this purpose is cut. Then, as a whole, the guide frame 27 drops until reaching the level of the upper end of the pallet; the conventional tamper 16, which is cylinder operated, stabilises the upper end pallet and fixes the cut plastic film to it.

The platform is rotated whilst the lift carriage 10 is moved upwardly so as to helically wrap the plastic film around the pallet reaching the top end area where this plastic film, surrounding the side pallet wall, fixes the plastic film covering the upper part of the pallet.

Optionally, by means of suitable programming of the machine, it is possible to arrange for an initial upward wrap on the side wall of the pallet, followed by the covering of the upper part of the base with a piece of plastic sheet and, then, finally, a further, downward, helical covering, so that the periphery of the strip covering the upper part of the base is secured between the two sheets of plastic covering on the side surface. This ensures a highly hermetic wrap.

All the elements of the machine, suitably combined and regulated by a control circuit, operate automatically to ensure that the wrapping of the pallets is carried out automatically, as already described, with no manual intervention.

Nevertheless, the machine has an opticalacoustic alarm system which warns that it has been stopped in the case of any possible failure.

The above arrangement can therefore be programmed to provide a machine in which the pallet is laterally wrapped and the top is sealed in a cycle of operations which is totally automatic from the moment a pallet enters the machine until it leaves. The arrangement thus allows the various procedural steps to be carried out with no manual interruption.

Claims

1. Apparatus for applying a wrapping of sheet material to a pallet, said apparatus comprising a platform for supporting a pallet and being mounted for rotation about a rotation axis, drive means for rotating said platform, sheet material dispensing means.disposed beside said platform and being mounted for movement in a direction generally parallel to said rotation axis, drive means for moving said sheet material dispensing means between a position adjacent the base of said pallet to a position adjacent the opposed end of said pallet and, clamp means mounted on said platform for rotation therewith and being operable to clamp the end region of a length of sheet dispensed by said dispenser.

2. Apparatus according to claim 1, wherein said sheet material dispenser dispenses thermoplastic sheet material and which further includes radiant heater means for being brought near the sheet material when wrapped on the pallet thereby to cause adjacent layers of said sheet material to become bonded.

3. Apparatus according to claim 2, wherein said radiant heater means includes electrical resistant heater elements.

4. Apparatus according to claim 2 or claim 3 which further includes roller means adapted to be brought into contact with said sheet material when wrapped on the pallet in the region thereof to be welded, thereby to assist welding.

5. Apparatus according to any of the preceding claims which further includes severing means associated with said sheet material dispenser for severing lengths of sheet material.

6. Apparatus according to claim 5, wherein said sheet material is thermoplastic and said severing means comprises an electrical resistance heater element.

7. Apparatus according to any of the preceding claims wherein the sheet material dispenser includes a rotatable reel of sheet material and wherein electromagnetic brake means are associated with said reel, said brake means being controlled to provide the sheet material with a predetermined degree of tension as it is applied to said pallet.

8. Apparatus according to claim 7 wherein means are provided to monitor the diameter of the reel and to control the electromagnetic brake means in accordance therewith.

9. Apparatus according to any of the pre ceding claims which includes further sheet material dispensing means mounted for movement in a plane generally transverse to said rotation axis and for dispensing a length of sheet material to cover the upper end of a pallet.

10. Apparatus according to claim 9 wherein said further sheet material dispenser stores sheet material on a rotatable reel and includes means to draw sheet material from said rotatable reel and to pass it over the upper end of a pallet to be wrapped.

11. Apparatus according to claim 10, wherein the means to draw the sheet material from said rotatable reel includes a feed carriage which is movable transversely to said rotation axis and which includes clamp-means operable to clamp the free end of a piece of sheet material.

12. Apparatus according to any of claims 9 to 11 wherein said further sheet material dispensing means includes a cutting device.

13. Apparatus according to any of claims 9 to 12 wherein said further sheet material dispensing means is mounted on a frame of generally rectangular form which includes in a central region thereof tamper means for engaging the upper end of a pallet to be wrapped thereby to provide stability for the pallet as it rotates.

14. Apparatus according to claim 11, wherein reel drive means and inertia brake means are associated with said reel and carriage drive means is associated with said carriage for effecting movement thereof and means are provided to effect movement of the further sheet material dispenser in a direction generally perpendicular to said rotation axis.

15. Apparatus according to claim 12, wherein said cutting device comprises an electrical resistance heater movable against a seating by means of a pneumatic cylinder.

16. Apparatus according to any of the preceding claims, which further includes control means for effecting operational control of the apparatus, photo-detector means for sensing the presence of a pallet on a platform and stroke limiters for controlling the operational phases of each cycle.

17. Apparatus according to any of the preceding claims wherein conveyor means are provided to supply pallets to said platform and to remove pallets therefrom.

18. A method of applying a wrapping of sheet material to a pailet, said method comprising locating a pallet on a rotatable platform having a clamp associated therewith; supplying sheet material from a dispenser to said clamp and operating said clamp to clamp the sheet material; rotating said platform whilst moving said dispenser in a direction generally parallel to the axis of rotation of said platform, thereby helically to wrap the pallet; severing said sheet material and then securing the severed end.

19. A method according to claim 18 which further includes the step of laying a length of sheet material over the upper end region of said pallet.

20. A method according to claim 18 or claim 19, wherein said sheet material dispenser maintained stationary for an initial period whilst said platform is rotated to overlap said sheet material over said pallet.

21. A method according to any one of claims 18 to 20, wherein said sheet dispenser is initially located adjacent the base of the pallet and is then moved adjacent the upper end of the pallet.

22. A method according to claim 21 when dependent on claim 19, wherein said length of sheet material is laid over the upper end of the pallet when the sheet dispenser is adjacent the upper end of the pallet whereafter the dispenser is brought back to a position adjacent the base of the pallet whilst rotating the platform, thereby to secure said upper sheet.

23. Apparatus for applying a wrapping of sheet material to a pallet substantially as hereinbefore described with reference to any bf the accompanying drawings.

24. A method for applying a wrapping of sheet material to a pallet substantially as hereinbefore described with reference to the accompanying drawings.

25. Any and all novel features and combinations thereof disclosed herein.