GB2520070A

GB2520070A - Gripping devices

Info

Publication number: GB2520070A
Application number: GB1319781.9A
Authority: GB
Inventors: Marius Andresen; Rolf Blomv Gnes; Kevin Geers; Christian Mide
Original assignee: K8 Industridesign AS
Current assignee: K8 Industridesign AS
Priority date: 2013-11-08
Filing date: 2013-11-08
Publication date: 2015-05-13
Also published as: GB201319781D0

Abstract

A gripping device 102, for gripping a flexible sheet material, comprises an outer body portion 104 and an inner body portion 106, the inner body portion being separated into a plurality of flaps 108 made of a resilient material. The flaps 108 extend inwardly from the outer body portion 104 and are deformable so as to define an aperture through the inner body portion 106 in the form of a plurality of inwardly extending openings between the flaps 108. Each flap 108 comprises a main portion, and an end portion 110 distal from the outer body portion 104, the main portion extending substantially in a plane, and the end portion 110 being angled away from the plane of the main portion. Preferably, a stop 116 opposes the deformation of the flaps beyond a maximum desired deformation.

Description

Gripping devices The present invention relates to gripping devices, in particular to gripping devices for gripping a flexible sheet material.

There are numerous examples in a wide range of fields of sheets made of flexible material which need to be fixed in a quick and convenient manner and also easily removed for retrieval or disposal between uses and/or replacement. For example, a towel stored adjacent a sink in a domestic residence for frequent use, or a cloth cover attached to a cleaning device that needs to be frequently replaced.

Known methods of storing or affixing such sheets include hooks and rails.

However, with such methods there is often a trade-off between the ease with which the item can be removed and replaced from the storage device and the degree to which the item is prone to falling off the storage device. For example, a sheet can be placed quickly and easily on a hook, but it can easily be knocked down. Or, in contrast, a sheet can be slowly and carefully threaded onto a rail or through slots in a holder, where it is less prone to falling off, but it may take longer to attach the sheet.

Gripping devices are known that address this problem, particularly in the context of holding domestic items such as towels or cleaning cloths. Such devices comprise a resiliently deformable planar surface with an aperture therethrough, the planar surface comprising closely spaced, converging flaps around the aperture. A flexible material sheet may be affixed to this gripping device by a user of the sheet pushing the flexible material through the aperture, the flaps bending to allow the passage of the item through the aperture, and then the user withdrawing their finger while the flaps grip the flexible sheet. Such devices are known from, for example, WO2012/127216.

However, such devices present a problem to users in that when a user inserts his/her finger through the aperture to push the flexible sheet through, the flaps deform not only to grip the material, but also the user's finger as it is withdrawn. In order to ensure adequate gripping of the flexible material, the flaps converge with sharp points that meet so that there is no gap between them. These points can dig into the user's finger causing discomfort. In some devices, it has been attempted to address this problem by eliminating the point at the end of the flaps and instead leaving an open space to accommodate a finger. However, this leads to a gap between the flaps where they would otherwise converge, resulting in poorer gripping of the flexible sheet. Especially for thin or low friction sheet materials the device may no longer be able to provide adequate gripping.

Examples of low friction sheet materials include foil sheets, coated paper, bubble wrap, plastic, synthetic textiles, film material, composite sheets comprising layers that may not be stuck together, e.g. wool between two layers of plastic, or thermal sheets (bubble wrap with foil on one or both sides). Thermal sheets pose a particular problem, as not only is the sheet low friction, but the sheet is also a lightweight material. Thermal blankets are typically used to keep patients warm, for example it may be desirable to fix such a thermal blanket over a hypothermic patient being transported on a stretcher. Such a situation is likely to occur outdoors where the sheet may be displaced by winds caused by, for example, ambient weather conditions or proximity to a rescue helicopter.

It is an aim of the present invention to provide an improved gripping device.

According to the present invention, there is provided a gripping device for gripping a flexible sheet material, the gripping device comprising an outer body portion and an inner body portion, the inner body portion being separated into a plurality of flaps made of a resilient material; the flaps extending inwardly from the outer body portion and being deformable so as to define an aperture through the inner body portion in the form of a plurality of inwardly extending openings between the flaps; each flap comprising a main portion, and an end portion distal from the outer body portion, the main portion extending substantially in a plane, and the end portion being angled away from the plane of the main portion.

A gripping device according to the present invention is thus provided with end portions that protrude out of the main plane of the inner body portion. This means that when a user pushes a flexible sheet into the aperture formed by deforming the flaps using a finger, the end portions are pushed aside, and any contact between the finger and the flaps is on the main portion of the flaps, not with the end portions.

The finger can then be taken out of the gripping device without pinching by the end portions. The flaps resiliently return to their initial positions once a finger is withdrawn, but the end portions of the flaps never contact the finger. The user can therefore insert his/her finger into the device and remove the finger without experiencing discomfort due to pinching by the device. The gripping device may therefore be provided with end portions that taper to a point so that the flaps converge with little or no gap between the end portions, thereby providing improved gripping of the flexible sheet, without risk of digging into a user's finger.

The device may be suitable for releasably gripping a sheet. For example, the gripping device may be made from a sufficiently flexible material, may have a gap between the end portions and/or may have sufficiently blunt or smooth end portions to allow the sheet to be removed from the gripping device without damage to the sheet.

The gripping device may be suitable for gripping a sheet securely enough that the sheet can only be removed from the gripping device by damaging the sheet, e.g. tearing the sheet by pulling it out of the gripping device. For example, the gripping device may be made from a sufficiently stiff material, may have a small gap or no gap between the end portions and/or may have sufficiently sharp or rough end portions to prevent the sheet from being removed from the gripping device without damage to the sheet. Such embodiments may be particularly suitable for gripping low friction sheets.

The main portions of the flaps are preferably substantially planar. The angled end portions are provided such that they are angled away from the plane of the main portion when the flaps are undeformed, e.g. due to permanent moulding of the shape of the flap to create a curve or hinge. However, the end portion may be further deformable by the pressure of a user's finger, e.g. the end portion may be bent further away from the main portion when a user pushes his/her finger into the gripping device.

The end portions are preferably angled downwardly, that is, in the direction that a user would insert a finger into the device. As the flaps deform, the end portions may bend down substantially vertically relative to the outer body portion, or even flex away at an angle greater than 90 degrees from the plane of the main portions of the flaps. As is mentioned above, the end portions may be pointed. However, in some embodiments the end portions may have a blunt edge but still take advantage of the invention by avoiding any end point pressure on a user's finger e.g. if the material of the flaps is relatively stiff. The end portions may be a sharp edge or may have a high friction or abrasive surface (e.g. a sandpaper effect).

Preferably the flaps are integrally formed, i.e. preferably the end portion and the main portion of each flap are formed from a single piece of resilient material.

However, the flaps may be formed by joining separate pads together. For example, the end portion may be made from a separate piece from the main portion, and the two pieces attached together. The two pieces may be attached at a hinge area or hinge line. The two pieces may be made from different materials or from the same material.

The end portions may touch when the flaps are undeformed, so that there is no gap between the flaps. This may provide a stronger grip on a sheet inserted into the gripping device. Alternatively, there may by a gap between the end portions when the flaps are undeformed.

Preferably the dimensions of the gripping device are suitable for a user to fix a sheet in the gripping device by pushing the sheet into the gripping device with a finger. However, in some embodiments, the dimensions of the device may be suitable for a user to fix a sheet in the device using an object or body part other than a fingei, e.g. a large gripping device may be suitable for a user to insert a sheet using a thumb, more than one finger, a hand, a foot, or an elbow.

In some embodiments, there is a hinge area between the main portion and the angled portion of each flap. The hinge area may be a hinge line. The hinge area may be a living hinge, i.e. it may be formed in the resilient material by providing a region of the resilient material that is more flexible, for example, it may be thinner or scored. In other embodiments, there is a curved region between the main portion and the angled portion of each flap. At least the inner portion may be formed from a single piece of resilient material, where inwardly extending cuts are made in the material to form the flaps. The end portions may be formed by moulding hinge areas or curved regions into the main portions of the flaps. Additionally or alternatively, the end portion may comprise an additional piece attached to the end portion. The additional piece may be made from a different material from the end portion. For example, the additional piece may be a metal point or spike or a high friction material such as rubber.

In some applications, it is useful for a user to be able to locate a gripping device without looking for it, but this can be difficult, particularly if the gripping device is provided flush with a surface in which it is installed. In some embodiments, the flaps form a surface that is substantially planar. However, in preferred embodiments, the flaps form a surface that is concave or convex when the flaps are undeformed by the pressure of a user's finger. In embodiments where the surface is concave or convex, a user can locate the flaps by feeling for a concave or convex region in a surface in which the gripping device is installed. This allows the user to insert a flexible sheet through the flaps without using their vision to locate the gripping device.

The gripping device may comprise a hinge area between each flap and the outer body portion. In embodiments with such hinge areas and also where the flaps form a surface that is substantially planar, the hinge areas between the flaps and the outer body portion may provide additional flexibility of the resiliently deformable material to help the resiliently deformable material deform to allow a user's finger to insert a flexible sheet material through the aperture. Alternatively, the hinge area may provide the only flexibility if the resiliently deformable material is stiff elsewhere. In embodiments where the surface is concave or convex, the main portion of each flap may meet the outer body portion at a hinge area such that the main portion of each flap is at an angle to the plane of the outer body portion.

Alternatively, the main portion of each flap may meet the outer body portion via a curved region such that in its undeformed state the inner body portion forms a concave or convex surface.

The gripping device may be made from any suitable material. In particular, the flaps may be made from any suitable resilient material. The flaps could be made from a springy metal, but preferably they are made from a plastics material, e.g. a thermoplastic or elastomeric material (which could be natural or synthetic).

The gripping device may comprise a stop arranged to oppose the deformation of the flaps beyond a maximum desired deformation by exerting a reaction force on the flaps. For example, the stop may have a structure and/or position that opposes the deformation of the flaps. Such a stop may help to prevent over-deforming of the flaps, for example, if a user inserts a bulky material into the gripping device, the extra volume of the material might otherwise result in the flaps bending to an extent that damages the gripping device. A stop may also help to ensure that the user is able to push the sheet sufficiently far through the inner body portion to allow the flaps to grip the sheet when the user's finger is removed. For example, without a stop, as a user's finger pushes a sheet material into the device, the flaps may bend an increasing amount as the finger inserts the sheet material further into the device.

This may result in a portion of the sheet material being pushed back out of the device as the finger is retracted and the flaps revert to their undeformed state. The provision of a stop allows a user to push a greater quantity of the sheet material into a gripped position. This may allow the gripping device to more effectively grip some materials, e.g. thin or low friction materials.

The stop could be any suitable shape, for example, it could comprise a number of protrusions, with one under each flap. It could comprise an annular wall positioned under the region between the end portions and the main portions of the flaps and extending in a direction generally transverse to the plane of the flaps. However, preferably the stop is a disc of rigid material positioned under the flaps and containing an aperture. For example, the diameter of such an aperture may be chosen to set the maximum desired deformation. Such a disc may be substantially parallel to the plane of the inner body portion of the device and may have the aperture positioned directly beneath a convergence point of the flaps.

In addition to providing a convenient and easy place to affix a flexible sheet when it is not in use, the present invention also provides a means to attach a flexible item in a desired position whilst it is in use. For example, in the field of cleaning devices, a mop head may be provided with gripping devices according to the present invention to allow a cloth or other flexible sheet to be affixed to the mop head for use during cleaning and then removed for disposal or washing prior to reuse.

As another example, in the medical field, it is often desirable to provide a cover over or a sheet under a person lying on a bed or stretcher. For example, there may be a need to quickly prepare stretchers during the provision of disaster relief. In particular, it is desirable to be able to fix the cover or sheet in place quickly and easily in such a manner that it is not likely to move from the desired position or fall off. In some embodiments, the gripping device is provided on a stretcher or bed. In some embodiments, a gripping device according to the present invention is provided on the bed or stretcher in each of a plurality of corners or extremities of a region for attaching a sheet.

The gripping devices of such embodiments can then be used to, for example, quickly affix a cover or blanket over or under a patient lying on a stretcher, where the gripping devices will hold the cover or blanket in place while the stretcher is carried or the bed is wheeled to an alternative location. The gripping devices also help to retain the cover oi blanket in place if the patient moves on the stretcher or bed, even if the stretcher or bed is not being moved between locations, e.g. if a stretcher is prepared for use outside in windy conditions.

The gripping device could be provided as a stand-alone device, for example, mounted on a wall in a kitchen for holding cloths and towels. The gripping device could be integrated into another device, e.g. into a stretcher or mop head. In such embodiments, the body of the other device, or a portion thereof, may be made from a suitable resilient material into which flaps may be cut to provide a gripping device according to the present invention.

Preferred embodiments of the present invention will now be described, by way of example only, and with reference to the accompanying drawings, in which: Figure 1 shows a perspective view of a gripping device according to an embodiment of the present invention.

Figure 2a shows a cross-sectional view of the gripping device of Figure 1.

Figure 2b shows the gripping device of Figure 2a incorporating an optional stop to resist the deformation of the flaps more than is necessary to allow the user to insert a sheet material.

Figure 2c shows the gripping device of Figure 2b with the stop resisting the deformation of the flaps as a user's finger is inserted into the device.

Figure 3 shows a perspective view of a second embodiment of the present invention.

Figures 4a to 4e show cross-sectional views showing five sequential stages of the insertion of a user's finger into the gripping device of Figs. 1, 2a and 2b and the removal of the user's finger from said device.

Figures 5a to Se show cross-sectional views showing five sequential stages of a user affixing flexible material item into the gripping device of Figs. 1, 2a and 2b.

Figure 6 shows an alternative embodiment of the gripping device in which the inner body surface of the gripping device is planar.

Figure 7 shows another alternative embodiment of the present invention in which the inner body surface is planar.

Figure 8 shows a further embodiment of the present invention in which the inner body surface of the gripping device is convex.

Figure 9a shows a stretcher with four gripping devices positioned to receive a fabric sheet to cover or to lie under a patient on the stretcher.

Figure 9b shows the stretcher of Figure 9a with a fabric blanket underneath a patient, with the blanket held in place by the gripping devices.

Figure 9c shows the stretcher of Figure 9a with a fabric cover held in place by the gripping devices.

Figure 1 shows a gripping device 102 in accordance with an embodiment of the present invention. The gripping device 102 is provided with an outer body portion 104 and an inner body portion 106. In this example, the inner body portion 106 comprises five flaps 108. Of course, any suitable number of flaps may be provided.

The flaps 108 are made of a resiliently deformable material, for example, polypropylene, thermoplastic polyethylene, polyamide, nylon. It will be appreciated that in other embodiments, the flaps may be made of a stiff material with a deformable hinge area.

The flaps 108 define a star-shaped aperture which is opened when the flaps 108 are deformed by pressure. The flaps 108 are oriented radially inwardly and downwardly at an angle to the plane of the outer body portion 104 such that the inner body portion 106 has a concave shape. The concave shape of the inner body portion 106 is convenient when a user wishes to insert a sheet material into the gripping device 102 without using their vision to locate the gripping device 102.

Instead, the user can locate the aperture in the gripping device 102 by feeling for the concave shape of the inner body portion 106.

It will be appreciated that the inner body portion need not have a circular, symmetrical shape. For example, the inner body portion could be rectangular, oval, triangular or any other suitable shape. The term inwardly extending' as applied herein to the flaps is not limited to devices having rotationally symmetric flaps converging radially to a single point. Inwardly extending includes devices in which at least some of the flaps extend towards each other or towards a substantially central point, line or area. flaps need not be radially convergent. As non-limiting examples, the flaps may form two convergence points at the ends of a slit, or may define a zig-zag shaped slit in the inner body portion.

The flaps 108 are substantially planar except for an angled end portion 110. The angled end portion 110 allows a user to insert his/her finger into the gripping device 102, in order to affix a sheet material, and then to withdraw the finger without suffering discomfort due to the pointed tips 114 of the flaps 108 pinching or digging into the finger.

Figure 2a shows a side cross-sectional view of the gripping device 102 of Figure 1.

The cross-sectional view shows the concave shape of the inner body portion 106.

The concave shape of the inner body portion 106 is achieved by means of a curved region 112 between each flap 108 and the outer body portion 104. This allows the flaps 108 to be planar rather than themselves curved. The angled end portions 110 of the flaps 108 protrude from the inner body portion 106. The tip 114 of each flap 108 is pointed. The pointed tips 114 help to grip a sheet material when itis pushed into the gripping device 102. The angled end portions 110 cause the pointed tips 114 to be directed away from a user's finger when it is inserted into the gripping device 102 so that the pointed tips 114 do not contact the user's finger.

Figure 2b shows an alternative embodiment in which a gripping device according to shown in Fig. 2a also comprises a stop 116 positioned beneath the flaps and extending in a direction generally parallel to the plane of the flaps.

Figure 2c shows the gripping device of Figure 2b, and shows the stop 116 resisting the deformation of the flaps 108 as a user's finger 118 is inserted into the device 102. When a user pushes his/her finger 118 into the gripping device 102, the stop 116 resiststhefurtherdeformation oftheflaps 108 oncetheflaps 108 have been deformed sufficiently to create an aperture for the finger and sheet material to pass through. This helps to guide the deformation of the flaps and allows the user to push the sheet material past the flaps 108 so that when he/she withdraws the finger 118, there is a sufficient material that has passed through the aperture for the flaps 108 to grip it. The stop 116 may also help to prevent the flaps 108 being damaged through being over-deformed. The stop could take any suitable shape, for example, a plurality of posts or arms, a disc with an aperture or an annular wall.

Figure 3 shows an alternative embodiment of a gripping device 302 according to the present invention. The gripping device 302 comprises an outer body portion 304 and an inner body portion 306, where the inner body portion 306 comprises five flaps 308. Each flap 308 is provided with an angled end portion 310, which directs the pointed tip 314 of the flap 308 away from a user's finger when the user's finger is pushed into the gripping device 302. In this embodiment, a hinge area 312 is provided between each flap 308 and the outer body portion 304 so that the flaps 308 extend radially inwardly and downwardly to form a concave shape. As in the embodiment described with reference to Figures 1 and 2, this concave shape allows a user to locate the aperture defined between the flaps 308 using their sense of touch. The end portions 310 of each flap 308 are angled away from the plane of each flap 308 by another hinge area 318.

Figures 4a to 4e show five sequential stages of a user inserting their finger into a gripping device 402 according to an embodiment of the present invention.

Figure 4a shows the gripping device 402 and the user's finger 420 prior to insertion of the user's finger 420. The flaps 408 of the gripping device 402 extend radially and downwardly in a concave shape, in a smooth curve similar to the device of Figures 1 and 2. The user's finger 420 is not in contact with the flaps 408 in Figure 4a, and so the flaps 408 are shown in their undeformed positions. It can be seen that the end portion 410 of each flap is already angled away from the general plane of the flap 408, extending downwardly at a greater angle than the rest of the flap 408.

In Figure 4b the user's finger 420 is shown making contact with the flaps 408 of the gripping device 402. The flaps 408, which are formed of a resiliently deformable material, begin to deform under the force applied by the user's finger 420.

Figure 4c shows the user's finger 420 partially inserted into the gripping device 402.

The flaps 408 are deformed to open up an aperture such that the user's finger can pass through the inner body portion 406 of the gripping device. As the flaps 408 deform by flexing downwardly, the angled end portions 410 of the flaps 408 become oriented vertically or even at an angle greater than 90 degrees from the outer body portion 404, such that the pointed tips 414 of the flaps 408 are directed substantially parallel to or away from the user's finger 420.

Figure 4d shows the user's finger 420 fully inserted through the aperture in the gripping device 402. Contact between the user's finger 420 and the flaps 408 is between the finger 420 and the top surface of the flaps 408, and not between the finger 420 and the pointed tips 414. The inset of tigure 4d shows a close-up view of the contact region between the finger 420 and the flaps 408. It can be seen that the angled end portions are deflected away from contacting the finger 420. -12-

Figure 4e shows the user's finger 420 immediately following removal from the gripping device 402. The finger 420 is removed from the aperture in the gripping device 402 without pinching of the finger 420 by the flaps 408 or discomfort caused by the pointed tips 414 digging into the user's finger 420. The flaps 408 resiliently move back to their original positions, but the pointed tips 414 never touch the finger 420. The inset of Figure 4e shows a close-up view of the region near the pointed tips 414.

Figures 5a to Se show corresponding sequential stages of the insertion of a user's finger 520 into a gripping device 502 as shown in Figures 4a to 4e, but with a flexible sheet material 522 positioned between the finger 520 and the gripping device 502 so that the user can affix the sheet material 522 in the gripping device 502.

Figure 5a shows the gripping device 502 just prior to insertion of the sheet 522 by the user's finger 520. Figure Sb shows the gripping device 502 as the finger 520, via the sheet 522, contacts the flaps 508 of the gripping device 502. Figure Sc shows the gripping device 502 with the user's finger 520 and the sheet 522 partially inserted therein. The flaps 508 deform to allow passage of the finger 520 and sheet 522 through the inner body portion 506.

Figure Sd shows the user's finger 520 inserted into the gripping device 502, having pushed the sheet 522 through the aperture in the inner body portion 506. The pointed tips 514 of the flaps 508 are directed away from the user's finger 520 due to the different angle of the angled end portions 510.

Figure Se shows the gripping device 502 with the sheet 522 gripped in the aperture by the flaps 508 immediately following removal of the user's finger 520. Once pressure is removed from the flaps 508, they move back to their initial configuration with the end portions 510 angled downwardly. The pointed tips 514 of the flaps 508 now grip the sheet 522, while the user is able to withdraw his/her finger 520 from the gripping device 502 without pinching by the flaps 508 and without discomfort caused by the tips 514 of the flaps 508 digging into the finger 520. The inset of Figure 5e shows a close-up view of the region close to the point of insertion of the finger 520 and sheet 522 into the aperture in the gripping device 502.

It will be appreciated that in any embodiment of the present invention, the inner body portion may comprise fewer or more than five flaps. Furthermore, it will be understood that it is not essential for the inner body portion to have a concave shape.

Figure 6 shows an alternative embodiment of a gripping device 602 according to the present invention. In this embodiment, the flaps 608 extend radially inwardly but not downwardly from the plane of the outer body portion 604, so the inner body portion 606 is substantially planar, rather than being concave. End portions 610 of the flaps 608 are angled by hinge areas 618 to extend downwardly at an angle from the flaps 608.

Figure 7 shows a gripping device 702 similar to that shown in Figure 6, except that the end portions 710 of the flaps 708 are angled by curved regions 718 rather than hinge areas.

Figure 8 shows a gripping device 802 similar to that shown in Figure 7, except that the flaps 808 extend radially inwardly and upwardly to the plane of the outer body portion 804, such that the flaps 808 form a convex inner body portion 806. It may be easier to locate a sheet of material over the aperture opened between the flaps 808 when the surface of the inner body portion is 806 is convex rather than planar.

In the embodiments of Figs. 6 to 8, the gripping device 602, 702, 802 in the same way as described above, to allow a user to insert a finger without being pinched by the end portions of the flaps.

Figure 9a shows gripping devices 902 in accordance with an embodiment of the present invention provided on the surface of a stretcher 924 occupied by a patient 926. Four gripping devices 902 are provided in this example, each gripping device 902 being provided in a corner of a region to be covered by a material sheet such as a blanket. -14-

Figure 9b shows the stretcher 924 of Figure 9a, carrying the patient 926, where a blanket 928 has been placed under the patient 926 and each corner of the blanket 928 has been inserted into a gripping device 902 provided on the stretcher 924.

The gripping devices 902 hold the blanket 928 in place under the patient 926. The gripping devices allow the stretcher to be quickly prepared for use. The corners of the blanket can be quickly pushed into the gripping devices eliminating the need for cumbersome fastening means that may be more time-consuming or dexterously demanding.

Figure 9c shows the stretcher 924 of Figure 9a, carrying the patient 926, where a blanket 928 has been placed over the patient 926 and each corner of the blanket 928 has been inserted into a gripping device 902 provided on the stretcher 924.

The gripping devices 902 hold the blanket 928 in place over the patient 926. It will be appreciated that the gripping devices 902 allow a blanket 928 to be quickly secured onto the stretcher 924 by hand, tightly gripped in place while the stretcher 924 is in use. This is particularly useful at times when the blanket might be prone to falling off, e.g. when the stretcher is being moved.

Claims

Claims 1. A gripping device for gripping a flexible sheet material, the gripping device comprising an outer body portion and an inner body portion, the inner body portion being separated into a plurality of flaps made of a resilient material; the flaps extending inwardly from the outer body portion and being deformable so as to define an aperture through the inner body portion in the form of a plurality of inwardly extending openings between the flaps; each flap comprising a main portion, and an end portion distal from the outer body portion, the main portion extending substantially in a plane, and the end portion being angled away from the plane of the main portion.
2. A gripping device as claimed in claim 1, wherein the end portion of each flap is pointed.
3. A gripping device as claimed in any of claims 1 or 2, wherein each flap comprises a hinge area between the main portion and the end portion.
4. A gripping device as claimed in any preceding claim, wherein each flap comprises a curved region between the main portion and the end portion.
5. A gripping device as claimed in any preceding claim, further comprising a stop arranged to oppose the deformation of the flaps beyond a maximum desired deformation by exerting a reaction force on the flaps.
6. A gripping device as claimed in any preceding claim, wherein the flaps form a surface that is substantially planar.
7. A gripping device as claimed in any of claims ito 5, wherein the flaps form a surface that is substantially concave.
8. A gripping device as claimed in any of claims 1 to 5, wherein the flaps form a surface that is convex.
9. A gripping device as claimed in any preceding claim, further comprising a hinge area between each flap and the outer body portion.
10. A gripping device as claimed in any preceding claim, further comprising a curved region between each flap and the outer body portion.
11. A gripping device as claimed in any preceding claim, wherein the inner body portion is integral with the outer body portion.
12. A gripping device as claimed in any preceding claim, wherein the flaps are made from one or more thermoplastic materials.
13. A gripping device as claimed in any preceding claim, wherein each flap comprises an additional piece attached to its respective end portion, and wherein the flaps are made from a first material and each additional piece is made from a second material, the first material being different from the second material.
14. A gripping device as claimed in any preceding claim, wherein the device is provided on a stretcher or bed.
15. A gripping device as claimed in claim 14, wherein the outer body portion is integral with the stretcher or bed.
16. A gripping device as claimed in claim 14 or 15, wherein the inner body portion is integral with the stretcher or bed.
17. A gripping device as claimed in any of claims 14, 15 or 16, wherein the stretcher or bed is provided with a gripping device according to any of claims ito 11 on the stretcher or bed in each of a plurality of corners or extremities of a region for attaching a sheet.
18. An assembly comprising: a gripping device as claimed in any preceding claim; and a sheet comprising a low friction material, wherein the sheet is held in the gripping device.
19. The use of a gripping device as claimed in any of claims ito 17 to hold a sheet comprising a low friction material.