GB2297534A

GB2297534A - Adjusting the width of a web of wrapping material

Info

Publication number: GB2297534A
Application number: GB9602136A
Authority: GB
Inventors: Gary Parker; Kevin Taylor
Original assignee: MANCON ENGINEERING Ltd
Current assignee: MANCON ENGINEERING Ltd
Priority date: 1995-02-03
Filing date: 1996-02-02
Publication date: 1996-08-07
Also published as: GB9502158D0; DE19603487A1; FI960492A0; GB9602136D0; FI960492A

Description

2297534 APPARATUS FOR WRAPPING AN OBJECT WITH A WEB OF MATERIAL This

invention relates to apparatus for wrapping an object with a web of material and to a method of sealing the end of a web of material that has been wrapped around an object.

The use of a wrapped web of material in the packaging of objects is widespread. It finds particular application in the packaging of material on pallets. The wrapped material can protect the wrapped objects during transportation from damage such as from impact. It can also serve to retain the objects on the pallet so that the pallet with its objects can be moved with reduced risk of the objects becoming loose and falling from the pallet.

Materials in web form that can be used in packaging include films, especially of thermoplastic polymeric material that can be heated to cause them to fuse. Such heating steps can be relied on to bond a cut end of the web to an underlying surf ace to seal the wrapped web. Such a seal will retain the wrapped web around the object so that it does not tend to unwrap. In some circumstances, the seal can be a seal which can resist flow of fluids especially when the web is of a continuous film. Otherwise, the seal can be effectively in the form of a seam, for example when the web is open as when it is a net.

It can be desirable to use a web of open material, that is to say a net, to wrap objects for some applications, for example when it is desirable for the wrapped objects to be ventilated. The bonding technique described above in relation to a film cannot be used with a net because of the reduced quantity of material that is available to bond to the underlying surface.

The present invention provides a technique for wrapping a web of material around an object, in which the configuration of the web is changed by reducing its transverse dimension.

In one aspect, the invention provides apparatus for wrapping an object with a web of material, which comprises a carriage unit on which are mounted:

(a) a mounting for a roll of the material of the web, from which the material of the web is dispensed, and (b) means for controlling the lateral extent of the web in a direction transverse to the direction in which the material of the web travels as it is dispensed from the roll, the control means being adjustable to vary the said lateral extent, the apparatus being arranged so that one of the carriage unit and the object to be wrapped can be rotated relative to the other to cause the object to be wrapped with the web material.

The apparatus of the invention enables the transverse dimension of a web of material to be reduced as it is dispensed, in effect to gather the web into a bunch. This has significant advantages. For example, when the web is open in the form of a net, it facilitates the formation of a secure bond of the cut end of the web of such material to an underlying surface, overcoming the problem of forming a bond to a open web. Furthermore, it enables a web of material to be gathered so that to change the physical characteristics of the web. For example, it can result in an increase in the strength of the web. Such a gathered web might be used as a restraining strap or tie, for example for an object or objects on a pallet.

The application of the web of material to an object (which might be in the form of a plurality of objects, for example in a stack) can be facilitated by arranging for (a) the object, and (b) the mounting for the web and the means for controlling the lateral extent of the web to rotate relative to one another. For example, the apparatus can include a turntable for the object as it is wrapped with the material of the web, dispensed from the carriage unit (which can then be stationary). The apparatus can include means for rotating the carriage unit for the roll of the web material around an object as it is wrapped with the material of the web, for example in the f orm of a track extending around the obj ect, or in the f orm of a limb on which the roll mounting and the lateral extent control means are mounted, the limb being mounted for rotation about a pivot.

Preferably, the means for controlling the lateral extent of the web comprises at least one arm which acts against the web, and is arranged so that it can slide to vary the lateral extent of the web of material. The arm will generally extend in a direction out of the plane of the web of the material, especially substantially perpendicular to the plane. It is preferred that the arm is arranged to slide substantially continuously in a direction substantially transverse to the direction in which the material of the web travels as it is dispensed to provide the said control over the lateral extent of the web. The continuous sliding movement makes it possible to vary the lateral extent of the web accurately over a range of positions of the arm, to provide the desired characteristics of the web. The continuous movement can be achieved by arranging the said arm so that it can slide along a track. The track can have a threaded external surface and the arm can engage that surface threadedly. The arm can in this way be made to move along the track by rotation of the track about its axis.

Preferably, the apparatus includes two of the said arms to control the lateral extent of the web at each of the two opposite edges of the web. It will be preferred for each of the arms to be capable of sliding in opposite directions in the said direction transverse to that in which the material of the web travels as it is dispensed. When the arms engage a common track threadedly and are made to move along the track by rotation of the track about its axis, the movement of two arms in opposite directions can be achieved by providing opposite threads on the track at its respective ends.

Preferably, the apparatus includes the web of material, as a roll, that is to be dispensed for wrapping around an object. The material can be, for example, a film or a net. Suitable film materials include polyolefin films (such as polyethylene or polypropylene films), polyamide films, polyester films and so on. Nets used for the web can be formed from polymers of these general types. The configuration of the net will depend on the application for which it is to be used. Suitable nets include, for example, ones with openings between the filaments measuring at least about 1 cm, preferably at least about 2 cm, for example at least about 4 cm. The openings preferably measure less than about 20 cm, more preferably less than about 15 cm, for example about 10 cm.

Preferably, the means for controlling the lateral extent of the web is able to reduce the lateral extent by at least about 50%, more preferably at least about 75%, especially at least about 90%, for example about 95%. Preferably, the control means is able to reduce the lateral extent to a number of values between zero and the maximum available reduction, especially to substantially any value between these limits. When the lateral extent is controlled by a single moveable arm, that arm will move from a position in which the web is at its maximum lateral extent to a position in which the maximum reduction is provided, which will generally result in one edge of the web being moved towards its opposite edge which remains When there are two moveable arms, it will generally be appropriate for each of the two arms to be arranged to move through equal distances to change the lateral extent of the web, for example towards a point substantially equidistant between the opposite edges of the web.

substantially unmoved The dimensions of the web will be selected according to the intended purpose of the web once wrapped. For example, suitable webs will have a normal transverse dimension (that is without any reduction) of at least about 10 cm, preferably at least about 20 cm, more preferably at least about 30 cm. The transverse dimension will often be less than about 150 cm, preferably less than about 75 cm, more preferably less than about 45 cm.

The apparatus can include means for tensioning the web as it is applied to the object to be wrapped. For example, the web can be tensioned by means of pairs rollers that the web passes between, the pairs of rollers having appropriately differing rates of rotation.

In another aspect, the invention provides a method of sealing the end of a web of material that has been wrapped around an object using apparatus of the type discussed above, which includes the steps of:

(a) adjusting the control means to reduce the lateral extent of the web as it is dispensed, and (b) f orming a bond between the web in a region in which its lateral extent has been reduced as aforesaid and the surface which underlies the web in that region.

The method can be operated using apparatus having features referred to above in the discussion of the apparatus of the invention. For example, the means for controlling the lateral extent of the web comprises at least one arm arranged so that it can slide to vary the lateral extent of the web of material, and in which the lateral extent of the web is reduced by sliding the arm. The means for controlling the lateral extent of the web can comprise two arms arranged so that they can slide in opposite directions to vary the lateral extent of the web of material by acting on opposite edges of the web, and in which the lateral extent of the web is reduced by sliding the arms relative to one another towards and away from one another.

The material of the web can be fusible, in which case the bond forming step of the method comprises heating the material of the web to cause it to fuse to the surface which underlies it.

The present invention will now be described, by way of example only, with reference to the accompanying drawings, in which:

Figure 1 is an isometric view of apparatus which can be used to wrap an object with a web of material; Figure 2 is a side elevation of the carriage of the apparatus shown in Figure 1, which bears mounting and feed components for the web of material.

Referring to the drawings, Figure 1 shows wrapping apparatus 2 which comprises a square frame 4 on support posts 6. An object to be wrapped can be located under the frame on a conveyor 8. Suitable objects can include a pallet bearing goods which are to retained on the pallet, for example for stability during transportation.

A circular track 10 is located within the frame and support posts, above the object that is located on the conveyor 8 to be wrapped. It can be moved upwardly and downwardly relative to the frame and the object, in directions indicated in Figure 1 by arrows 11. A carriage 12 is mounted on the track f or movement along the track, involving rotation around the object. The track 10 includes power take off rails for electrically powered components on the carriage, in conventional manner.

As shown in Figure 2, the carriage includes a mounting 14 for a roll 16 of the web of material with which the object is to be wrapped. The web is dispensed for wrapping from the roll over a guide member 18. Downstream of the guide member, the web passes between two arms 20 which extend in a direction substantially perpendicular to the plane of the web at the point which it passes between them. The arms are movable transversely relative to the direction with which the web is dispensed from the carriage, generally in the directions indicated in Figure 2 by arrows 22.

The arms 20 are mounted on an externally threaded rod 24 which serves as a track along which the arms can be slid. The rod is threaded in two portions 24a, 24b, the thread in the two portions being of opposite hands. Each of the arms has an opening extending through it, through which the rod passes. The opening in each of the arms is threaded on its internal surface.

The rod 24 is driven by an electric motor on the top of the carriage, to which power is supplied through the take off rails associated with the track 10. By supplying power to the motor, the rod 24 can be made to rotate and the arms be made to move towards one another or away from one another. It is common for the power supplied through the take off rails associated with the track of apparatus of this kind to be direct current; in this event, the direction of the motor can be changed by reversing the polarity of the supply to the motor. End stops to the movement of the arms can be provided by appropriately positioned switches.

In operation, an object that is to be wrapped is positioned on the conveyor 8 under the frame 4 inside the support posts 6. The object might be, for example a stack of cartons on a pallet. The carriage 12 is then made to rotate around the object on the track 10, feeding the web material from the roll 16 as it rotates, to wrap around the object. The track 10 moves upwardly and downwardly as appropriate to ensure that the object is covered over its full height or otherwise as required.

During normal wrapping of the object, the arms 20 on the carriage, between which the web passes as it is dispensed from the carriage, leave the width of the web substantially 8_ unaffected to that the web the transverse dimension of the web is not reduced. The transverse dimension might be reduced during wrapping (other than when it is desired to seal a cut end of the web) to gather the web into a band so that its physical characteristics change, for example, to increase the strength of the web. The gathered web might then be used as a restraining strap or tie for the object. It is so gathered by movement of the arms 20 towards one another by causing the rod 24 to rotate.

After the web in its gathered configuration has been wrapped around the object as required, the web can be cut and the cut end sealed while the web is gathered. A technique for sealing the web is described below. Alternatively, the arms 20 can be moved apart (by rotating the rod 24 in the direction opposite to that which causes the arms to move towards one another) and the width of the web to increase towards or to its full width, and further wraps of the web material can then be applied to the object.

When enough of the material of the web has been wrapped around the object, for example to achieve the stability of cartons on a pallet that is necessary for transportation, the web can be sealed so that it can be cut. A web of an open material such as in the form of a net can be sealed by f irst reducing the width of the web by moving the arms 20 towards one another as described above. This causes the web to bunch, effectively closing the open areas within the web, facilitating the formation of a strong bond to the surface underlying the web.

When the web is formed of a material which can sof ten when heated, the bond can be formed by application of pressure to the web using a heated bar. The bar is applied to the web in a region in which its width is reduced, pressing the web in that region against the surface underlying the web. The surface underlying the web might be provided by underlying wrapped layers of the web, or by another material such as that of an object that is being wrapped. When the surface under the web in the region in which the bond is to be formed is provided by underlying layers of the web, it is preferred that there are at least two of the said layers in that region.

A rigid support can be provided under the layers of material to be bonded, as they are contacted by the bar. An appropriate support might be in the form of, for example, a metal plate. It can be provided with a coating of an appropriate release material (such as a layer of a fluoropolymer) to ensure that it can be removed from under the layers after the bond has been formed.

The bond between the web and the underlying surface need not be provided by heating the material of the web to cause it to soften. For example, it might be provided by means of an adhesive material. Suitable adhesive materials can be selected according to the materials of the web and the underlying surface (if different). Suitable adhesive materials can be applied using heat, for example as hot-melt adhesives or heat curable adhesives.

Once the bond between the web and the underlying material has been made, the web can be cut. once the track 10 has been raised sufficiently, the object is removed from under the frame and the wrapping process restarted for another object.

Claims

CLAIMS:

1. Apparatus for wrapping an object with a web of material, which comprises a carriage unit on which are mounted:

2. Apparatus as claimed in claim 1, in which the means for controlling the lateral extent of the web comprises at least one arm which acts against the web, and is arranged so that it can slide to in a direction substantially parallel to the axis of the roll of the web material, substantially transverse to the direction in which the material of the web travels as it is dispensed, to vary the lateral extent of the web.

3. Apparatus as claimed in claim 2, in which the said arm is arranged to slide along a track.

4. Apparatus as claimed in claim 3, in which the arm engages the track threadedly, and in which the track is mounted to rotate about its axis to cause the arm to move along the track.

5. Apparatus as claimed in any one of claims 2 to 4, which includes two of the said arms, arranged to slide in opposite directions in the said direction transverse to that in which the material of the web travels as it is dispensed.

6. A method of sealing the end of a web of material that has been wrapped around an object using apparatus as claimed in any one of claims 1 to 5, which includes the steps of:

7. A method as claimed in claim 6, in which the lateral extent of the web is reduced from opposite sides of the web.

8. A method as claimed in claim 6 or claim 7, in which the material of the web is fusible and in which the bond forming step of the method comprises heating the material of the web to cause it to fuse to the surface which underlies it.

9. A method as claimed in any one of claims 6 to 8, in which the material of the web comprises a net.