EP0253610A1

EP0253610A1 - Curtain heading

Info

Publication number: EP0253610A1
Application number: EP87306177A
Authority: EP
Inventors: Peter Kingsley Bayly
Original assignee: Bayly Design Assoc Pty Ltd
Current assignee: Bayly Design Assoc Pty Ltd
Priority date: 1986-07-14
Filing date: 1987-07-13
Publication date: 1988-01-20

Abstract

A curtain header tape 1 formed of a thermoplastic material having a memorary facility such that the tape will adopt a pre-established form when unrestrained. The tape is divided into a plurality of panels 3, 4 and at least some 3 of those panels are formed so as to have a fold inducing characteristic 7, which may be a shape characteristic or an internal stress, characteristic. The arrangement is such that each such panel 3 will naturally tend to adopt a folded or bent condition when left unrestrained, and the apex of that fold or bend is at the same side of the tape for all such panels. The tape may also include intervening panels 4 which have a configuration inducing characteristic 16 such that each will adopt a predetermined configuration in response to being folded or bent. Attachment of the tape 1 to the head of a curtain results in the foregoing fold and configuration characteristics being imparted to the curtain head. Clip means may be used to retain each configuration panel in the bent or folded form at which the configuration is induced.

Description

This invention relates to drapes or curtains and is concerned with the heading of such curtains. The invention will be hereinafter described with reference to fabric curtains, but it is to be understood that the invention is applicable to curtains and drapes of other materials.
Curtains are generally mounted in such a way as to enable movement between extended and folded conditions at which they cover and expose respectively an opening, window, door or whatever. For that purpose it is usual to provide an overhead elongate track having travellers or gliders attached thereto for movement therealong, and the curtain is mounted by attachment to the travellers. A cord and pulley system is sometimes attached to at least one of the travellers to provide a convenient means for drawing the curtain between its extended and folded conditions.
It is usual to provide folds or pleats in the head portion of a curtain so as to impart an attractive appearance both in the folded and extended conditions of the curtain. One method of achieving that is to stitch the folds in place, but that has the disadvantage of making it awkward to wash or clean the curtain. Another method is to secure, e.g., by stitching, a cloth header tape to the top section of the curtain. That tape is provided with attachment points for wire clips which are used to attach the curtain to the track travellers, and when those clips are correctly attached through the intermediary of the tape a series of folds is naturally formed in the curtain head. A disadvantage of this method is that it does not allow for a wide variety of fold forms and is generally limited to forming folds of the kind commonly referred to as pinch pleats.
A more recent proposal involves the use of a flexible metal strip which is preformed to naturally adopt a folded or collapsed condition. The preform is such that the strip has a series of arcuate bends which alternately face one way and then the other so that the strip is somewhat sinusoidal when in the extended condition. When collapsed, however, the bends are tightly packed together and that is the condition which the strip naturally seeks to adopt. In use the metal strip is inserted into a pocket in the top section or head of the curtain, and special clips are employed to secure the strip to a the track travellers.
Several problems exist in the system last described. One is that the metal strip is capable of only limited extension and consequently the curtain may extend over a relatively large area when in the folded condition. Another problem is the need for a relatively complicated traveller system. Yet another problem arises from the need to support the metal strip in such a way that the traveller track is located directly above the curtain and it is therefore not possible to extend the curtain head across the track to hide it from view. Still another problem is the need to provide means for restraining the curtain in the extended position since the metal strip naturally tends to return towards the collapsed condition.
It is an object of the present invention to provide a relatively simple and effective method and means for forming folds or pleats in a curtain head. It is a further object of the invention to provide such means which enables adoption of any of a large variety of fold forms and/or patterns.
In accordance with the invention a header tape is used to provide at least the basis of the folds to be imparted to the curtain. That tape is preformed so as to impart folds of a pre-established form and pattern, but differs from the prior metal strip in that it can be stored in a flattened and perhaps rolled condition. The tape is made of a material having a memory facility such that it will naturally tend to adopt the fold creating condition when left unrestrained. On the other hand, the tape can be collapsed between the fold creating zones and can be extended without the need for restraints as in the prior metal strip system. In some cases, at least the tape may not have sufficient rigidity to completely form the folds when attached to a curtain so that clips or other releasable fixing means may be required to fix the folds in their final form.
The essential characteristics of the tape according to the invention is that it has an inherent capability to move, when unrestrained, towards the fold forming condition. It is a further characteristic of the tape that the form and pattern of the folds can be pre-established by appropriate presetting of the tape and the tape has sufficient memory to return from a flattened condition towards the preset condition. In a preferred form, the tape is able to be washed or cleaned without causing significant loss of the memory facility, but in other forms that particular characteristic may not be necessary.
If the tape is to have a substantially permanent memory, it may be formed from a plastics sheet material such as a thermoplastic which can be heat set in a folded condition. Preferably, the tape is formed of a thermoplastic and rubber composite and one such composite material is sold by Monsato under the trade mark "SANTOPRENE", and grade 203-40 of that material has been found satisfactory. A strip of that material may be heat set to form fold lines along its length and each of those lines functions somewhat in the manner of a flexible hinge when the strip is forced into a flattened condition. If the restraint which causes the flattening is removed, however, the material will naturally tend to bend at the fold lines, at least to a limited extent and in that way the basis of the desired curtain folds or pleats is created. Furthermore, that facility is not destroyed by washing or cleaning of the tape, even in hot water.
In some circumstances, it may not be necessary to have such a degree of permanence in the tape, and under those circumstances the tape could be formed of any relatively form stable but flexible material which has some degree of memory. For example, paperboard, plasticised fabric, and similar materials may be suitable in some cases since such materials have sufficient memory to return from a flattened condition towards a prefolded condition.
As a matter of convenience, however, the invention will be hereinafter described as applied to a tape made from a thermoplastic material or a thermoplastic and rubber composite.
In accordance with the present invention, there is provided a curtain heading tape formed of a flexible but relatively form stable material and having a plurality of panels provided along its length, each said panel being defined between two boundary lines each of which extends between the opposite longitudinal edges of said tape, a fold zone is provided within each of at least some of said panels, each of which constitutes a fold panel, each said fold zone extends between said longitudinal edges, and each said fold panel is formed so as to have a natural tendency to develop a fold in one direction about the respective said fold zone when said tape is not restrained against such folding.
In the foregoing passage, and subsequent passages of this specification, the reference to the tape being "restrained against....folding" is to be understood as meaning that the tape is subjected to tension so as to remove any transverse folds or corrugations, or is otherwise urged into a relatively flat condition. The reference to "relatively form stable" is to be understood as meaning that the tape material is inherently self-supporting to an extent greater than is fabric of the kind from which curtains or drapes are typically fashioned.
The "fold" which is referred to above may be a relatively sharp fold, in which event the fold zone is a relatively narrow zone or line, or it may be a gradual bend of say curved configuration. Also, the "form" of the fold panel which induces the fold may be a shape characteristic, or it may be a stress characteristic built into the panel. In either case, the form establishes a "set" in the panel which causes the panel to normally adopt a non-flat condition.
Embodiments of the invention are described in detail in the following passages of the specificaton which refer to the accompanying drawings. The drawings, however, are merely illustrative of how the invention might be put into effect, so that the specific form and arrangement of the various features as shown is not to be understood as limiting on the invention.
In the drawings:

Figure 1 is a front elevation view of a section of tape according to one embodiment of the invention,
Figure 2 is a view of the tape of Figure 1 looking in the direction of the line II-II,
Figure 3 is a part sectional view taken along line III-III of Figure 1,
Figure 4 is an enlarged cross-sectional view taken along line IV-IV of Figure 1,
Figure 5 is an enlarged cross-sectional view taken along line V-V of Figure 1,
Figure 6 is an enlarged cross-sectional view taken along line VI-VI of Figure 1,
Figure 7 is an enlarged cross-sectional view taken along line VII-VII of Figure 1,
Figure 8 is an edge-on view of the tape shown in Figure 1 when placed under tension so as to remove the corrugations as shown in Figure 3,
Figure 9 is a rear elevation view of a clip for use with the tape of the preceding Figures,
Figure 10 is a side elevation view of the clip shown in Figure 9,
Figure 11 is a perspective view of a tape as shown in Figure 1 to which the clip of Figures 9 and 10 has been attached and which is subjected to tension so as to remove the corrugations shown in Figure 3,
Figure 12 is a view similar to Figure 11 but looking from the rear side of the tape,
Figure 13 is a view similar to Figure 11 but showing the tape in its collapsed or folded condition,
Figure 14 is a view of the clip of Figure 9 attached to a curtain track system,
Figure 15 is a cross-sectional view taken along line XV-XV of Figure 14,
Figure 16 is a diagrammatic view of a curtain attached to a track system through the tape of Figure 1,
Figure 17 is a view similar to Figure 1 but showing another form of tape according to the invention,
Figure 18 is a view taken along line XVIII-XVIII of Figure 17.

A tape formed of say a thermoplastic and rubber composite is flexible but relatively form stable and consequently can be heat set to provide at least the basis of the folds or pleats to be imparted to the curtain with which the tape is to be used. The fold lines in the tape which dictate the form and pattern of the curtain folds can be straight or curved and they can extend as required relative to the longitudinal axis of the tape. For example, if the tape is to form the basis for conventional goblet folds, the fold lines will be straight and will extend transverse to the tape longitudinal axis. In a variation, however, the upper portion of each goblet fold may be formed as an arcuate depression, and for that purpose an arcuate fold would be provided in the tape at an appropriate position between each two transverse fold lines which are intended to form the ends of a goblet fold.
Figures 1, 2 and 3 of the drawings show a tape 1 which has been formed under heat and pressure to produce a "set" in the tape which will cause a particular fold appearance in a curtain with which the tape is used. The tape 1 is divided into a plurality of panels, each of which is defined between two boundary lines 2, and in the particular arrangement shown, adjacent panels share a common boundary line 2. The tape 1 shown has two forms of panels which will be respectively referred to as fold panels 3 and configuration panels 4. The panels 3 and 4 are arranged in alternating sequence, but that is not essential since more than one fold panel 3 could be provided between adjacent configuration panels 4, and/or more than one configuration panel 4 could be provided between adjacent fold panels 3.
Each boundary line 2 as shown is a substantially straight line, or zone, which extends between the longitudinal edges 5 and 6 of the tape 1 and at right angles to those edges. Other arrangements are clearly possible.
The edge-on view of the tape 1 shown by Figure 3 is a representation of that particular tape in its as-formed and unrestrained condition. That is, the somewhat corrugated form shown is the form which the tape 1 naturally adopts when not restrained. The tape 1 can be stored flat, or in a rolled and therefore flattened condition, without disturbing its tendency to naturally seek the corrugated form shown by Figure 3. That is, the tape 1 has a memory facility.
Each of the fold panels 3 is formed to achieve the aforementioned tendency and the nature of that form can vary according to the type of pattern and/or configuration required. In the example shown, each fold panel is provided with a fold line 7 which extends between the tape edges 5 and 6 and is located substantially midway in the width of the respective panel 3. Also, each fold line is straight and is at right angles to the edges 5 and 6, but other arrangements are possible. By way of example, the panel 3 may be arranged to bend gradually at a zone rather than fold sharply about a line as shown, and the width of that zone may vary according to circumstances.
In the particular arrangement shown, the fold inducing form of each panel 3 comprises at least one web 8 (Figure 4) which is intersected by the longitudinal axis of the fold line 7 and which in effect forms a short and integral link between the parts 9 and 10 of the panel 3 on each side of the fold line 7. As is best seen in Figures 1 and 2, there is a plurality of webs 8 on each line 7, and those webs 8 are spaced apart along the fold line 7. Furthermore, each web 8 forms the base of a respective shallow depression 11 formed in a front surface 12 of the tape 1, and each of those depressions 11 forms an interruption in the fold line 7.
Each depression 11 as shown is curved in the direction of the respective fold line 7 so as to have its maximum depth intermediate its length in the direction of the fold line 7. On the other hand, the base of each depression 11 is substantially flat in a direction transverse to the fold line 7 as is shown by Figure 4.
When the tape 1 is flattened as shown in Figure 8, the webs 8 are forced out of their natural as-formed state and that sets up stress within the region of the fold lines 7 which tends to restore the fold panels 3 to the condition shown in Figure 3 when the tape is unrestrained. It will be obvious that other types of fold inducing forms could be adopted to achieve the same result.
It is preferred, as shown in Figure 5, that the portions of each fold line 7 extending between the depressions ll, each constitutes a narrow zone of reduced thickness. A depression or groove 13 is formed in the tape front surface 12 to produce that effect. As is evident from Figures 4 and 5, the groove 13 extends along and is formed in the apex 14 of the fold created at the fold line 7. The groove 13 facilitates relative movement of the two panel parts 9 and 10 to the extent permitted by the restraining influence of the webs 8.
Each configuration panel 4 of the tape 1 as shown is formed to produce a particular configuration when the tape 1 is folded as shown in Figures 11 and 12. It will be seen from Figure 13 that the configuration of the panels 4 in this instance is such that each projects in the same direction as do the fold panels 3 when they are folded or collapsed. In the particular construction shown, each configuration panel 4 is formed to produce a scalloped appearance at the front of the head of an associated curtain 15 (Figure 16). That configuration inducing form comprises two lines of weakness 16, each of which is located in a central region of the respective panel 4 and extends between the tape edges 5 and 6. As shown in Figure 1, each line 16 curves away from the other, but their ends meet with the tape edge 5 or 6 at substantially the same point. A sharp ended oval is thereby defined between the two lines 16. In the construction shown, each line 16 is formed by a groove in the front surface 12 of the tape 1 (Figure 7).
With the foregoing arrangement, when the boundary lines 2 at each end of a panel 4 are moved towards one another to collapse the panel 4, there is a natural tendency for the panel 4 to crease or bend along each of the two lines 16. The result is as shown in Figures 11 and 13. That is, a curved depression or scallop is formed in the front surface of the tape in the area between the lines 16. That depression is curved in a direction transverse to the longitudinal direction of the tape 1, and is substantially flat in the longitudinal direction of the tape 1. Other arrangements will produce other effects.
A wire clip 17 is provided to hold each panel 4 in the form as shown in Figure 11. Figures 9 and 10 show one type of clip 17 which is suitable for that purpose. The clip 17 includes two straight legs 18 which are located side by side and which are connected at their respective lower ends to a mounting part 19 of inverted U-shape. That mounting part 19 is arranged to cooperate with a glider 20 (Figures 14 and 15) of a curtain track system as hereinafter discussed. Each leg 18 is connected to the mounting part 19 through a joining section 21 which is preferably arranged so that the tape 1 can be gripped or at least neatly confined between that section 21 and the legs 18.
In the construction shown, each boundary line 2 is formed so as to facilitate attachment of the clips 17 to the tape l. As shown in Figure 6, each line 2 is formed by a narrow channel section 22 which extends between the tape edges 5 and 6. The channel section 22, in the embodiment shown, is formed by two side walls 23 which are relatively arranged so that the channel is of substantially V-shape in transverse cross-section. Furthermore, as shown, the channel or depression which forms the internal surface of the section 22 is formed in the front surface 12 of the tape 1.
Grooves 24 and 25 are formed in the rear surface 26 of the tape 1 on respective opposite sides of each channel section 22 so as to form lines of weakness. Each groove 24 in particular serves as a hinge about which a panel part 9 or 10 can move relative to the adjacent panel 4.
A hole 27 (Figure 1) is formed in the side wall 23 of each channel section 22 which is adjacent the respective panel 4, and at a location adjacent the tape edge 6. A respective leg 18 of a clip 17 is passed through each of the holes 27 at the ends of a panel 4 and is located within a respective one of the channel sections 22 so as to extend longitudinally thereof as shown in Figure 11. The panel 4 is thereby retained in the configuration forming condition and the mounting part 19 of the clip 17 is arranged for cooperative engagement with a glider 20.
The tape 1 has a series of holes 28 (Figure 1) formed therethrough to facilitate attachment of a cord system (not shown) for drawing an associated curtain 15 between its collapsed and extended conditions.
The manner of cooperation between a clip 17 and a glider 20 is shown by Figures 14 and 15, and is explained in greater detail in our copending patent application PH 6901, filed l4th July, 1986. The upper portion 29 of the clip mounting part 19 is neatly located between a surface 30 of the glider body 31 and a flange-like member 32 which is attached to the surface 30 in spaced relationship through a block member 33 (Figure 15). The mounting part 19 rests on the block member 33 to be supported by the glider 20 and the confinement of the upper portion 29 between the member 32 and surface 30 effectively prevents movement of the clip 17 relative to the glider other than in an upward and outward direction as is necessary to separate the two components. A lower portion 34 of the mounting part 19 engages against a lower portion of the surface 30 and is laterally confined between two wings 35 which project outwards from that surface 30. The clip 17 therefore serves as an extension of the glider 20 so as to provide a firm - i.e., non-tiltable - support for the tape 1 and attached curtain 15 (Figure 16).
In the arrangement shown, the glider 20 cooperates with the curtain system track 36 so as to be held against relative tilting movement, and that cooperation is explained in the aforementioned copending application PH 6901. Nevertheless, it will be apparent from Figure 15 that the downward load applied to the glider 20 when in use is positioned forwardly of the point of support 37 between the glider and the track 36, and rearward relative tilting movement of the glider is prevented by abutments 38 and 39 located within the track 36 and a roller 40 which engages against an outside surface of the track 36. It is to be understood, however, that a tape according to the invention is not limited to use with a glider 20 as shown.
Figures 17 and 18 show a variation of the tape 1 in which all panels are fold panels 3. A tape of that form will naturally attempt to adopt the corrugated configuration as shown by Figure 18.
It is possible to create a great variety of fold forms and patterns by use of a tape as described. For example, it is possible to produce folds which extend generally in the longitudinal direction of the curtain head - i.e., "horizontal" folds - in addition to or alternative to the conventional vertical folds...such a. facility is not available with any prior curtain folding system other than one in which the folds are permanently secured in place by stitching, for example.
A tape according to the invention could be attached to a curtain by stitching or other securing means, or it could be simply inserted in an appropriate pocket formed in the curtain head. In either case, the curtain can be conveniently washed or cleaned since the tape can be flattened, or removed if desired, to facilitate such washing or cleaning.
In view of the flexible nature of the tape, it may not be sufficiently stable in the folded condition to produce and maintain complete folds in a curtain. Under those circumstances, the clips previously described may be constructed so as to provide sufficient support to retain the folds.
Although it is generally sufficient to use a single tape in accordance with the invention, relatively complex fold forms and/or patterns can be achieved by use of two or more tapes located in parallel relationship at the curtain head. Each tape may be preset to control a particular aspect of the fold form or pattern and those tapes may or may not be laterally spaced according to requirements.
Use of a tape according to the invention enables the curtain head to be extended upwards to cover the associated track assembly.
It will be appreciated that the present invention provides a significant advance over prior curtain folding systems. The preset tape is convenient to use and does not disturb the ability to wash or clean the curtain even when it is permanently secured to that curtain. Furthermore, the tape enables creation of a great variety of fold forms and patterns including creation of horizontal, curved and angled folds whether alone or in combination with vertical folds.

Claims

1. A curtain heading tape formed of a flexible but relatively form stable material and having a plurality of panels provided along its length, each said panel being defined between two boundary lines each of which extends between the opposite longitudinal edges of said tape, a fold zone is provided within each of at least some of said panels, each of which constitutes a fold panel, each said fold zone extends between said longitudinal edges, and each said fold panel is formed so as to have a natural tendency to develop a fold in one direction about the respective said fold zone when said tape is not restrained against such folding.

2. A tape according to claim 1, wherein each said boundary line and each said fold zone is a substantially straight line extending substantially at right angles to the longitudinal edges of said tape.

3. A tape according to claim 1 or 2, wherein each said fold zone has at least one interruption formed therein, said interruption comprises a web which is intersected by the longitudinal axis of the respective said fold zone and which extends beneath the apex of the fold created at that zone when said tape is unrestrained, and each said web forms an integral part of the respective said panel.

4. A tape according to claim 3, wherein each said web constitutes a fold inducing form of the respective said fold panel which is at least partly responsible for said natural tendency.

5. A tape according to claim 3 or 4, wherein a. plurality of said interruptions are provided along each said fold zone and are spaced apart in the longitudinal direction of the respective said zone.

6. A tape according to claim 3, 4 or 5, wherein each said interruption is in the form of a shallow depression which is curved in the longitudinal direction of the respective said fold zone so as to have a maximum depth intermediate its length in the direction of that fold zone, and is substantially flat in a direction transverse to the respective said fold zone.

7. A tape according to any preceding claim, wherein each said fold zone is formed by a narrow zone of reduced thickness.

8. A tape according to claim 7, wherein said zone of reduced thickness is formed by a groove in a front side surface of said tape, and that groove extends along the apex of the fold created at the respective said fold zone.

9. A tape according to any preceding claim, wherein said one direction is the same for each said fold panel.

10. A tape according to claim 1, wherein each said panel constitutes a said fold panel and adjacent said fold panels share a common said boundary line.

11. A tape according to any one of claims 1 to 9, wherein each of a plurality of said panels constitutes a configuration panel, and each said configuration panel is arranged to adopt a predetermined configuration as a consequence of movement of the adjacent two said boundary lines towards one another.

12. A tape according to claim 11, wherein said panels comprise alternating fold and configuration panels, and each two adjacent panels share a common said boundary line.

13. A tape according to claim 11 or 12, wherein each said configuration panel is formed so as to adopt a predetermined configuration when not in a flat condition, and said predetermined configuration includes projection of at least part of said configuration panel in the direction of the apex of the fold created at each said fold zone.

14. A tape according to any one of claims 11 to 13, wherein each said configuration panel has a configuration inducing form which includes at least one line of weakness formed in the respective said panel so that the panel will .tend to bend about that line.

15. A tape according to claim 14, wherein each said configuration panel includes two said lines of weakness, each said line of weakness extends between the longitudinal edges of said tape at a location substantially midway between the two boundary lines of the respective said configuration panel and is curved between its ends, and each of the opposite ends of each said line of weakness meets a respective one of the longitudinal edges of said tape at substantially the same point as does the corresponding end of the other said line of weakness.

16. A tape according to claim 14 or 15, wherein the or each said line of weakness is formed by a narrow groove in a front side surface of said strip, and the apex of the fold created at each said zone is also at said front side surface.

17. A tape according to any one of claims 11 to 16, wherein clip means retains each said configuration panel in the form of a closed loop which projects in the same direction as the apex of the fold created at each said fold zone.

18. A tape according to claim 17, wherein each said clip means holds the two boundary lines of the respective said configuration panel in close side by side relationship.

19. A tape according to any one of claims 11 to 16, wherein a hole is formed through said tape adjacent each said boundary line and adjacent one said longitudinal edge of the tape, and a clip is receivable in each of the said holes at each side of a respective said configuration panel so as to hold that panel in the form of a closed loop.

20. A tape according to claim 19, wherein each said boundary line includes a narrow section of said tape which is of channel shape in transverse cross-section and which extends transversely between the longitudinal edges of said tape, the depression which forms the internal surface of each said channel section is formed in a front side surface of said tape, and said clip includes two elongate legs each of which is adapted to pass through a respective said hole and locate within a respective said channel section so as to extend longitudinally of that channel section.

21. A tape according to claim 20, wherein each said channel section is of substantially V-shape in transverse cross-section and a said hole is formed in the side wall of that channel section which is remote from the respective adjacent said fold panel.

22. A tape according to claim 20 or 21, wherein a narrow zone of reduced thickness is formed in each said strip on each side of each said channel section, and each said zone extends between the longitudinal edges of said tape.

23. A tape according to claim 22, wherein each said narrow zone of reduced thickness is formed by a groove in the rear side surface of said tape.

24. A tape according to claim 22 or 23, wherein each said narrow zone adjacent a said fold panel forms a hinge about which that fold panel can move relative to the respective adjacent configuration panel.

25. A tape according to claim 17, wherein each said clip means includes two elongate legs arranged in close side by side relationship, each said boundary line includes a narrow section of said tape which is of channel shape in transverse cross-section and which extends in a straight line between the longitudinal edges of the tape, a hole is formed in each said channel section adjacent one said longitudinal edge of the tape, and each said leg extends through a respective said hole of the two said boundary lines of the respective said configuration panel and is located within the respective said channel section so as to extend longitudinally thereof.

26. A tape according to claim 25, wherein each said clip means includes a mounting part of inverted U-shape which is connected to each said leg and is adapted to engage with a glider of a curtain track system to support said tape on the track of that system.

27. A tape according to claim 26 in combination with a curtain track system which includes an elongate track and a plurality of gliders supported on said track for relative movement in the longitudinal direction thereof, wherein each said clip is supported by and coacts with a respective said glider so as to be restrained against relative movement thereto in a plurality of directions, and each said clip and the respective said glider coact so as to retain said tape with its front and rear side surfaces substantially vertical.

28. A tape according to any preceding claim, wherein said tape material is of a kind such that it will naturally return towards a pre-established shape when forced out of that shape.