Mechanical Joining Of Flexible Sheet Material To Connecting And Supporting Corelines, For Large Panel Uses

Abstract

Flexible sheet material is attached to coreline (i.e., rod, rope, cable), either to splice sheet margins into a composite of larger span, or to attach a large sheet to a plurality of supports some of which may be at intermediate points of the sheet, or merely to support ends or side margins of a sheet, by releasably clamping the sheet material to the coreline by means of split tubing of friction material held thereto by split relatively rigid tubular retainer. Joined sheet margins are thereby connected in airtight relation. Releasable securing of flexible strips or panels into sheets usable for various purposes, and supporting of the sheets and carrying of the sheets as in air-supported enclosures is facilitated. Erection and dismantling of air-supported enclosures is simplified.

Description

This invention relates to mechanical joining of flexible sheet material to connecting and supporting corelines, and is more particularly concerned with large panel uses of such material.

Practical considerations limit the widths of which flexible sheet material such as canvas, heavy-duty plastic sheet, reinforced sheeting, and the like can be produced and handled. To attain large area coverage such as for tents, inflated enclosures, stockpile covers, ground covers, and the like, it has heretofore been customary to sew, bond, fuse, or otherwise permanently secure strips of the material together in the larger panel format. Not only the securing of the material into panels, but also the handling of such permanently secured panels is difficult and burdensome. Should any strip portion of a panel become damaged, replacement is often virtually precluded or at least can be effected only with great difficulty and loss of time. Especially in the erection and dismantling of inflated enclosures, great cost in handling, transportation, erection and dismantling procedures and storage problems seriously limit adoption and use of this type of shelter in spite of the manifest advantages where temporary shelters or enclosures are desirable.

Support of shelters and other types of enclosures such as inflated building or shed-like enclosures has generally involved equipping the structure with various types of attaching devices, grommets, anchor connections, and the like, in addition to the fastenings required for securing sheet strips together and adding to the cost and complexity of the structure.

An important object of the present invention is to overcome the foregoing and other disadvantages, defects, inefficiencies, shortcomings and problems in prior methods and structures and to attain important advantages and improvements by the mechanical joining of flexible sheet material to connecting and supporting corelines, for lage panel uses, and in other respects as will hereinafter become apparent.

Another object of the invention is to provide new and improved method of and means for separable connecting flexible sheet material to provide large panels.

A further object of the invention is to provide new and improved method of and means for connecting flexible sheet material to corelines which may be tendinous.

Still another object of the invention is to provide a new and improved connector for sheet material which is especially suitable for field splicing use, being simple and easy to perform and being substantially unaffected by moisture, dirt or other contamination.

A still further object of the invention is to provide a new and improved connector for flexible sheet material enabling use of steel cable tendons in such a manner that the tendons may extend from the connected panel at one or both ends of the joints in which the tendons provide corelines so that the projecting portions of the tendons may serve as freely extending hold-down or anchoring stays for shelter-type uses of the associated panel.

Yet another object of the invention is to provide new and improved flexible sheet material covers, shelters and enclosures.

Other objects, feature and advantages of the invention will be readily apparent from the following description of certain preferred embodiments thereof, taken in conjunction with the accompanying drawings, although variations and modifications may be effected without departing from the spirit and scope of the novel concepts embodied in the disclosure, and in which:

FIG. 1 is a schematic top plan view of a shelter or enclosure embodying features of the invention;

FIG. 2 is a sectional view taken substantially along the line II--II of FIG. 1;

FIG. 3 is a sectional view taken substantially along the line III--III of FIG. 1;

FIG. 4 is an enlarged fragmentary sectional detail view taken substantially along the line IV--IV of FIG. 1;

FIG. 5 is a sectional elevational view of a device for effecting assembly of a split clamping tube with flexible sheet material on a coreline;

FIG. 6 is a side elevational view of the device;

FIG. 7 is a top plan view of the device;

FIG. 8 is a fragmentary side elevational view demonstrating a manner of assembly of a splut tubular retainer with the clamping tube to complete the assembly;

FIG. 9 is an elevational sectional view taken substantially along the line IX--IX of FIG. 8; and

FIG. 10 is a fragmentary sectional view demonstrating means for at least temporarily connecting overlapping sheet margins in effecting a splicing connection.

According to the present invention, flexible sheet material is attached to coreline (i.e., rod, rope, cable), either to splice sheet margins into a composite of larger span, or to attach a large sheet to a plurality of supports some of which may be at intermediate points of the sheet, or merely to support ends or side margins of a sheet, by releasably clamping the sheet material to the coreline by means of split tubing of friction material held thereto by split relativey rigid tubular retainer. Joined sheet margins are thereby connected in airtight relation. Releasable securing of flexible strips or sheets into panels usable for various purposes, and anchoring and supporting of the panels as in frame or air-supported enclosures, stockpile or other covers or otherwise, is facilitated. Erection and dismantling of large area covers and enclosures is simplified.

By way of example of a particular utility for the present invention, a shelter 10 in the form of an air-supported or inflated enclosure is depicted. This may be in the nature of a temporary building over a building site, a protective shelter over a storage area, a sports arena shelter, a temporary field office and/or workshop, or the like. It may be of any practical size, such as on the order of 70 feet long and 75 to 50 feet wide and as much as 20 feet high at the center and 10 or 11 feet high about the perimeter, to accommodate a building site. The magnitude of mere bulk of material for such a structure will be appreciated.

According to the present invention the structure 10 comprises a plurality of parallel strips 11 of suitable flexible sheet material such as canvas, heavy-duty plastic sheet, reinforced plastic sheet, or the like, each strip in the assembly being of on the order of 10 feet wide, in this instance each strip extending continuously the full width of the structure, with suitably arc-shaped strips 12 at the respective opposite ends, and a skirt strip 13 extending in one length or a plurality of connected lengths around the entire perimeter of the structure. Principal support for the structure is provided by transversely extending ropes or cables 14, with a perimeter rope or cable 15 attached by suitable connectors 17 to the cables 14 with span not only across the inflatable enclosure but also extend suitably as stays or guys therebeyond and are attached at their ends to anchors 18 such as stakes driven into the ground in the nature of tent stakes. At the ends of the enclosure the arcuate portions of the perimeter cable 15 are ground-anchored by means of stay or guy ropes or cables 19 to ground anchors 20 such as stakes driven into the ground. At their ends the panel sections or strips 11 are secured to the perimeter line 15 as is also the outer edge of the end panels 12, together with the upper edge of the skirt 13, while the lower edge of the skirt 13 is suitably secured to an anchoring base 21 which may be a continuous wood frame.

For inflating the enclosure 10, a suitable blower heater 22 is desirably connected in communication therewith to maintain a desirable inflating pressure within the inflated structure and at a suitable temperature. Where desirable, the blower may be combined with a cooling unit for maintaining the internal temperature of the inflated structure at a desirable value.

One or more entrances 23 may be provided in the wall defined by the skirt 13. Each entrance is outlined by a suitable frame carrying a door 24 adapted to be opened, preferably inwardly so that air pressure will tend to close the same.

Where the inflatable structure 10 is erected at asite having a prevailing or frequent wind of useful velocity and direction, means may be provided for utilizing the wind to supply inflation air pressure. By way of example, this is adapted to be effected by automatic wind valve means 25 in the wall provided by the skirt 13. Such valve means comprise a suitable hole 27 midway between the upper and lower edges of the skirt 13 and preferably of a vertically elongated form and of suitable area such as on the order of about 2 feet wide and 3 feet high where the wall is on the order of 10 or 11 feet high. Extending across the opening 27 at the outer side of the wall 13 is a flexible valve panel 28 which is fixedly attached to the perimeter line 15 and to the base 21 but has its side edges free with respect to the wall 13. By having the valve panel 28 slightly shorter than the width of the skirt wall panel, internal air pressure within the enclosure 10 will cause the skirt to press against the valve panel 28 and thus close the valve opening 27 against escape of air, as depicted in full line in FIG. 3. When it is desired to take advantage of wind velocity to inflate, maintain inflation or assist in inflation of theinflated enclsoure, the wind pressure is permited to belly the skirt 13 inwardly so that the area of the skirt facing the valve panel 28 will belly away from the valve panel, due to the short differential in the length of the panel relative to the skirt, as indicated in dash outline in FIG. 3, so that the wind pressure can enter into the enclosure through the valve hole 27. It will be appreciated, of course, that there may be as many of the wind pressure valves 25 as desired in any or all stretches or faces of the wall provided by the skirt 13. This ability of the skirt wall to "kick-through" provides for a stable airsupported structure using, where the natural air pressure is available, substantially less pump-generated inflating pressure than normally required. Further, added internal pressure may be desired during heavy winds to prevent undulation, and through this device the wind itself is enabled to supply additional inflation air pressure to tighten the roof against undulation or whipping.

Erection of the enclosure 10, as well as dismantling thereof, is greatly facilitated by having the panel sections or strips 11 and 12 as well as the skirt 13 separably secured in the assembly. This is accomplished by mechanical joining means comprising releasable grippers 29 (FIGS. 1 and 4), utilizing the lines 14 and 15 as corelines onto which the flexible material is secured. To this end, side marginal portions 11a of the flexible sheet material strip panel sections 11 are lapped over one another and medially engaged against the associated line 14 and frictionally clamped thereagainst by means of a longitudinally split resiliently flexible clamping tube 30 formed from suitable elastomeric friction material and retained in clamping engagement by relatively rigid longitudinally slotted tubular retainer 31. It will be understood, of course, that the diameter of the tubes 30 and 31, respectively, will be predetermined to effect a firm gripping relationship on and about the clamped sheet margins 11a by the clamping tube 30 and about the clamping tube 30 by the retainer tube 31, with the tubes engaging the sheet margins 11a about the perimeter of the coreline 14 except to the extent of the split in the tube 30 and the narrow slot in the tube 31 providing clearance for the lapped sheet marginw where they extend from the gripper assembly. Material from which the retainer tubes 31 are made may comprise rigid plastic, aluminum, steel, as preferred. Aluminum and plastic have the advantage of resistance to corrosion and of being lightweight, as well as readily susceptible to mass production by extrusion methods of manufacture. At the slot in the retainer tube 31, suitably smoothly rounded shaped edges 32 are desirably provided adapted to maintain the lapped sheet edge portions 11a tucked toward one another and squeezed together as seen in FIGS. 4 and 5 at the split in the tube 30 without damage to the stretched apart sheet material sections 11 laterally forced against the edges when the structure is inflated. By holding the clamping tube 30 against spreading when lateral force is applied through the connected sheet panel sections, a firm frictional snubbing grip is maintained on and against the marginal sheet portions clamped between the coreline 14 and the clamping tube 30, preventing escape and effecting a thoroughly leakproof joint. Even though the joint thus provided is thoroughly secure and tight, it is readily separable when desired. Although the mechanical joint 29 has been described particularly in connection with the sheet strips 11 and the cables 14, it will be appreciated that the same relationship prevails where the perimeter line 15 serves as coreline for connection between the ends of the strips 11 and the skirt wall strip 13 and between the line 15 and the outer edge of the end panels 12 and the skirt 13.

In order to effect preliminary assembly of the sheet margins 11a in preferred overlapping relation, a strip of adhesive 11b (FIG. 10) may be applied to adhere the overlapping margins together. Such adhesive is readily available in so-called double-stick tape form (for example, Scotch 4Y30 Tape) enabling convenient field use of the adhesive. Further, such adhesive securing of the laminated margins is particularly useful where an extremely smooth and friction-free sheet material is used such as solid or cross-laminated polyethylene sheets. Thereby the sheet margins are preliminarily retained and then after the generally closed C-shaped clamping tube 30 and the rigid slotted C-shaped gripping tube 31 has been applied, the adhesive 11b cooperates with the gripping, clamping action of the clamping gripper assembly to positively retain the sheet margins against relative slipping.

A salient advantage of the mechanical joint 29 resides in that the several sheet material pieces can readily be assembled at the site on which the inflatable building 10 is to be erected and there attached to the corelines, on the ground, whereafter the structure is inflated or otherwise erected such as in the manner of a tent, if preferred. Where the assembly is to be merely a supine cover over a stockpile, the flexible sheet material and corelines are adapted to be assembled and connected via means of the mechanical joints and the assembled panel then pulled or rolled or lifted onto the stockpile and fastened down. Although guy ropes or cables may serve as the corelines, where desired the corelines may comprise suitable rods. While the joint devices 29 are especially suitable for joining flexible sheet material margins, where desired, connection of already permanently secured or one-piece panels to corelines may be effected, for the convenience of separable connection.

Assembly of the split clamping tube 30 may be effected manually, but for large installations it is desirable to employ an applicator 33 such as the device shown in FIGS. 5, 6 and 7. This device is operative to guide the split clamping tubing as a continuous strip into position and apply it to the assembled sheet material and coreline continuously throughout any preferred length or span. In addition, the device 33 is adapted to receive the clamping tubing 30 as a continuous tube and to split the same before application to the assembly. To this end, the device 33 includes a manipulating handle 34 having attached to one end thereof as by means of a fastener 35 a body plate 37 provided with a forwardly extending overhanging flange 38 in which is a guide aperture 30 through which an endless strip of the tube 30 projects toward an applicator roller 40 rotatably supported by and between flanges 41 of a roller bracket 42 secured to the body 37 by means of the fastener 35.

In use of the applicator device 33, suitable diameter solid elastomeric tubing of indefinite length is threaded endwise through the guide opening 39. Tubing practical for this purpose may, for example, be 70 durometer neoprene tubing. In advancing the tubing 30 into and through the guide hole passage, it is automatically split by means of a combination guiding and knife blade 43 carried by the flange 38 and projecting from the rear edge on the radius of the guide hole 39 partially into the hole and having a slanted knife edge directed upstream relative to the advancing tubing to slice longitudinally through the tubing wall and the blade then cooperating with the split edges of the tubing to hold the tubing against turning as it advances through the guide hole passage so that the split tubing will remain properly oriented for application to the sheet and coreline assembly.

After passing through the guide passage provided by the hole 39, the split tubing 30 is desirably spread by means of a spreader butt extension 43a from the blade/guide 43 before engaging a small diameter spreader roller 44, freely rotatably supported by and between the flanges 41. The roller 44 is properly related in spaced relation to the preferably crowned perimeter of the applicator roller 40 to maintain the spread condition of the resiliently flexible split tube wall as the tubing runs in backed relation against the roller 40. At its leading free end, the split tubing 30 is clampingly fitted to the sheet and coreline assembly, with or without the aid of the applicator, and the tool is manipulated to press and run the roller 40 against and along the assembly. The tubing 30 looped over the roller 40 pays out automatically as the roller runs backwardly therealong. This causes the tubing to be simultaneously advanced through the guide passage opening 39 and along the splitter knife 43 and applied rapidly to the assembly. Long span lengths of joint can thus be quickly and easily supplied with the clamping tubing 30. At the end of the span the tubing is severed, leaving a sufficient lead length projecting beyond the roller 40 to start the next assembly run. By reason of its resilience or memory factor, the tubing 30 at the edges defining the split therein springs closed and it therefore automatically grips the embraced sheet material and coreline in the assembly, immediately on being released from the spreading effect of the rollers 40 and 44. It may be noted that the terminal portion of the guiding and knife blade 43 which projects toward the advancing tubing is blunt to avoid scoring the wall of the tubing should it come in contact therewith.

To facilitate application of the retainer tubes 31, they are preferably provided in relatively short sections. A practical length of about one foot has been found satisfactory, although to meet special circumstances shorter or longer lengths may be employed. As a further convenience, the clamping tubing 30 is desirably provided at suitable intervals along its length with parallel diagonal, opposite side lead-in grooves 45 (FIGS. 8 and 9) in its perimeter. These grooves 45 are just deep enough to enable passing of the edges defining the slot in the retainer tube 31 as it is thrust toward and into engagement with the clamping tube 30 in the assembly, substantially as indicated in FIGS. 7 and 8. By way of example, the lead-in grooves 45 may be provided at about 5 foot intervals along the tube 30, since in a 4 or 5 foot distance it is relatively easy to maneuver a short section such as 1 foot length of the retainer tube 31 into position along the clamping tube 30, even though the base upon which the assembly is lying during the assembly operation may be relatively uneven. By having the retainer tube sections 31 relatively short, not only is assembly facilitated but the short section retainer tube arrangement also facilitates handling of the assembly in rolled condition where that is necessary for any reason and also bending of the assembly when mounted on a flexible coreline. The short sections of the retainer tube 31 and the lead-in grooves in the clamping tube 30 also facilitate disassembly separation where necessary since the relatively rigid retainer tube sections can be readily backed out of the assembled relation by way of the grooves 45 in reverse to the assembly step. After the retainer tubes 31 have been removed, the clamping tubes 30 can be easily stripped from the assembly. For reuse thereafter, the clamping tubes 30 can be either manually applied to a sheet and coreline assembly or the length of the tube can be threaded through the applicator tool 33 for application to the assembly.

Although all sections of the sheet material may be field-assembled and spliced and connected by means of the novel joint 29, conveniently-handled large components may be shop-assembled and provided with spliced joints either according to the present invention or according to any other preferred splicing technique which may require shop-based equipment, such as heat-sealing equipment, and then the components assembled and joined with marginal splices according to the teachings of the present invention on the erection site in the field. Thereby, very large structures may be erected conveniently and quickly with minimum equipment in the field. Inasmuch as the connection effected by the present invention is substantially unaffected by moisture, dirt or other contamination, the present method and splicing device is adapted for use under conditions which would make prior field splicing difficult, if not impossible. Especially advantageous is the erection of shelters in which the corelines serve as tendons providing freely extending anchor or stay portions which are enabled to extend freely from the roof panel portion of the structure without any need for grommets or other means for attaching the stays, since the stays are integral extension from the coreline. Thereby greater inherent strength is built into the structure with maximum assurances against failure at any point.

It will be understood that variations and modifications may be effected without departing from the spirit and scope of the novel concepts of this invention.

Claims

I claim as my invention:

1. Means for mechanically connecting flexible sheet material to a coreline, comprising:

flexible longitudinally split elastomeric clamping tubing for embracing and clamping the sheet material onto and in embracing relation to the coreline;

relatively rigid longitudinally split retainer tubing for embracing and clampingly retaining said clamping tubing;

said clamping tubing having edges adapted to be in close opposition in the assembly; and

said retainer tubing having edges spaced apart and being smoothly rounded in cross sectional shape to avoid damage to the sheet material where the sheet material extends from the assembly.

2. Means according to claim 1, wherein said retainer tubing is of substantial thickness, and the outer sides of the margins of the retainer tubing at said edges are chamfered from said edges to facilitate damage-free stretching of clamped sheet material laterally along said edges.

3. Means for mechanically connecting flexible sheet material to a coreline, comprising:

flexible longitudinally split elastomeric clamping tubing for embracing and clamping the sheet material onto and in embracing relation to the coreline;

relatively rigid longitudinally split retainer tubing for embracing and clampingly retaining said clamping tubing;

said retainer tubing being in relatively shorter lengths than said clamping tubeing; and

said clamping tubing having peripheral grooves facilitating endwise assembly of the retainer tubing with the clamping tubing.

4. Means according to claim 3, wherein said peripheral grooves extend diagonally relative to the axis of the clamping tubing.

5. Means according to claim 4, said grooves being provided at diametrically opposite sides of said clamping tubing and the grooves extending in parallel relation.

6. In combination with a coreline having flexible sheet material embracing the coreline and extending laterally a substantial distance beyond the coreline;

a length of resiliently flexible elastomeric tubing split longitudinally to facilitate assembly with and snugly embracing and holding the sheet material in embracing relation about the coreline, the edges along the split in the tubing normally tending to close on one another;

a length of relatively rigid longitudinally slotted tubing snugly embracing said elastomeric tubing and maintaining it in clamping engagement about the sheet material embracing the coreline;

the split in said elastomeric tubing and the slot in said rigid tubing being in registration and the sheet material being squeezed together by the edges defining the split in the elastomeric tubing where the sheet material extends from the split by the rigid tubing retaining said elastomeric tubing against spreading open at the split;

whereby the flexible sheet material is firmly retained against displacement from its embracing relation to the coreline against pull on the sheet material transversely relative to the tubing assembly.

7. A combination according to claim 6, wherein said rigid tubing has its edges along the slot therein smoothly rounded in cross sectional shape to avoid damage to the sheet material where the material extends from the assembly.

8. A combination according to claim 7, wherein said rigid tubing has chamfers along the outer sides of the margins defining the slot edges to facilitate damage-free extension of the laterally extending sheet material therealong.

9. A combination according to claim 6, wherein said elastomeric tubing extends for a substantial length along the coreline, and said rigid tubing comprises a plurality of shorter sections.

10. A combination according to claim 9, wherein the elastomeric tubing has peripheral grooves facilitating endwise assembly of the rigid tubing sections.

11. A combination according to claim 10, wherein said grooves are oblique relative to the axis of the tubing and are parallel relative to one another.

12. A method of connecting flexible sheet material to a coreline, comprising:

applying elastomeric means in the form of resiliently flexible split tubing to embrace the sheet material and effect embracing of the sheet material with the coreline including spreading of the split tubing and applying it to and about the assembled sheet material and coreline; and

applying relatively rigid retainer means by assembling the retainer means in the form of longitudinally slotted relatively rigid tubing onto and in embracing relation to the clamping tubing.

13. A method according to claim 12, including splitting the elastomeric tubing, guiding the split tubing in spread relation toward the sheet material and coreline assembly, and pressing the spread tubing into clamping relation to the sheet material and coreline assembly.

14. A method according to claim 13, comprising rollingly spreading and pressing the split elastomeric tubing.

15. A method according to claim 12, including overlapping margins of separate pieces of the sheet material, applying double sticking tape between said margins to secure them against slipping, and placing the thus secured margins in embracing relation to the coreline before applying the elastomeric split tubing in embracing relation therewith.

16. In combination:

a flexible coreline;

flexible sheet material embracing a substantial length of said coreline and extending laterally therefrom;

elastomeric clamping means frictionally grippingly embracing said sheet material continuously throughout said length; and

a plurality of lengths of rigid slotted tubing which are of short length and extend in end-to-end relation and gripping embracing relation to said elastomeric clamping means and retaining it against separation from the clamping relation to the sheet material and coreline.

17. A combination according to claim 16, wherein said elastomeric clamping means comprises a length of resiliently flexible elastomeric tubing which1has a normally solid wall but is split longitudinally to facilitate assembly with the sheet material embracing the coreline and with the split edges pushing toward one another against the sheet material where it emerges from the split in the tubing, and said lengths of rigid tubing having slots which are slightly wider than the split in the elastomeric tubing whereby to facilitate lateral extension of said material but nevertheless maintaining the split edges pushing together.

18. A combination according to claim 17, in which said elastomeric clamping tubing has means thereon to facilitate assembly into clamping relation therewith and separation therefrom of said lengths of rigid tubing by movement of the lengths of rigid tubing across the clamping tubing and also lengthwise of the clamping tubing.

19. A combination according to claim 16, wherein said sheet material comprises separate pieces having overlapping margins thereof embracing said coreline, and double sticking tape between and holding said margins against relative slipping.

20. A method of connecting flexible sheet material to a flexible coreline, comprising:

applying the flexible sheet material into embracing relation along a substantial length of the coreline and extending laterally therefrom;

applying elastomeric clamping means in frictionally gripping clamping embracing relation to said sheet material continuously throughout said length; and

applying a splurality of lengths of rigid slotted tubing slidably into end-to-end clamping embracing relation to said elastomeric clamping means and thereby retaining the elastomeric clamping means against separation from clamping relation to the sheet material and coreline.

21. A method according to claim 20, including overlapping margins of separate pieces of the sheet material, applying double sticking tape between said margins to secure them against slipping, and placing the thus secured margins in embracing relation to the coreline before applying the elastomeric clamping means in embracing relation therewith.

22. In combination with a coreline having flexible sheet material embracing the coreline and extending laterally a substantial distance beyond the coreline;

a length of resiliently flexible elastomeric tubing split longitudinally to facilitate assembly with and snugly embracing and holding the sheet material in embracing relation about the coreline;

a length of relatively rigid longitudinally slotted tubing snugly embracing said elastomeric tubing and maintaining it in clamping engagement about the sheet material enbracing the coreline;

the split in said elastomeric tubing and the slot in said rigid tubing being in registration and the sheet material being squeezed together where it extends from the split in the elastomeric tubing whereby the flexible sheet material is firmly retained against displacement from its embracing relation to the coreline against pull on the sheet material transversely relative to the tubing assembly; and

said rigid tubing has its edges along the slot therein smoothly rounded in cross sectional shape to avoid damage to the sheet material where the material extends from the assembly.

23. A combination according to claim 22, wherein said rigid tubing has chamfers along the outer sides of the margins defining the slot edges to facilitate damage-free extension of the laterally extending sheet material therealong.

24. In combination with a coreline having flexible sheet material embracing the coreline and extending laterally a substantial distance beyond the coreline;

a length of resiliently flexible elastomeric tubing split longitudinally to facilitate assembly with and snugly embracing and holding the sheet material in embracing relation about the coreline;

a length of relatively rigid longitudinally slotted tubing snugly embracing said elastomeric tubing and maintaining it in clamping engagement about the sheet material embracing the coreline;

the split in said elastomeric tubing and the slot in said rigid tubing being in registration and the sheet material being squeezed together where it extends from the split in the elastomeric tubing whereby the flexible sheet material is firmly retained against displacement from its embracing relation to the coreline against pull on the sheet material transversely relative to the tubing assembly;

said elastomeric tubing extending for a substantial length along the coreline; and

said rigid tubing comprising a plurality of shorter sections;

said elastomeric tubing having peripheral grooves facilitating endwise assembly of the rigid tubing sections thereacross and then into coaxial assembly with the elastomeric tubing.

25. A combination according to claim 24, wherein said grooves are oblique relative to the axis of the tubing and are parallel relative to one another.