GB2039820A - Moulded Resin Structures - Google Patents

Abstract

A method of forming a rib or beam on a substrate 5 comprises providing a strip or sheet formed to be erectable into predetermined tubular form having a base surface, erecting it into and securing it in the said predetermined tubular form, securing the base surface of the resulting tubular member to the substrate 5, and then moulding a curable reinforced (e.g. with filaments or fibres) plastics composition over the exposed surface of the tubular form and into engagement with the adjacent surface portions of the substrate, and causing or allowing the composition to cure to form the rib or beam. Internal support, which may be temporary, is preferably provided for the tubular member at least during application of the curable resin composition. <IMAGE>

Description

SPECIFICATION Moulded Resin Structures The present invention relates to moulded resin structures, and provides a method of forming a rib or beam on a substrate, the method comprising providing a strip or sheet formed to be erectable into predetermined tubular form having a base surface, erecting it into and securing it in the said predetermined tubular form, securing the base surface of the resulting tubular member to the substrate, and then moulding a curable reinforced (e.g. with filaments or fibres) plastics composition over the exposed surface of the tubular member and into engagement with the adjacent surface portions of the substrate, and causing or allowing the composition to cure to form the rib or beam.

The tubular member may for example be of rectangular (e.g. square) cross-section, but is preferably of "top hat" cross-section. The strip or sheet is suitably of cardboard or like material; it may be a single layer flat strip or sheet, and may be formed for erection into the predetermined tubular form for example by scoring longitudinally where it is to be folded; where the erected tubular member is to have rounded corners, e.g. as in the two upper corners of the preferred "top hat" tubular member, a plurality of closely adjacent parallel score lines may be formed in the strip or sheet. In the case of materials such as cardboard, the fold lines may instead be defined by partially delaminating the material in a narrow zone where the fold is to be made. The strip or sheet may instead be provided in lay-flat tubular form, especially in the case of large cross-sectional sizes.

Where the strip or sheet is not in lay-flat tubular form, it is preferably formed to be erectable into the predetermined tubular form with its longitudinal edge portions overlapping, these overlapping portions then being secured together. In this case, the strip or sheet preferably has holes and/or press-out portions spaced along its length and so disposed as to provide lateral openings into the erected tubular member facilitating the application of fixing means to secure the overlapping portions together; preferably, the openings are such as to permit the positioning of the anvil of a stapler against the inner of the overlapping portions so that these can be stapled together, but other fixing members and devices could be used. This allows long lengths of tube to be erected and secured rapidly and efficiently.

Since the moulding of the reinforced plastics composition involves the application of pressure to the tubular member, the latter, especially when made of relatively flimsy material such as cardboard, may need to be supported internally at spaced regions along its length. A variety of such supports are described hereinafter. Since the moulded rib or beam once cured does not require internal support, the internal supports themselves may be relatively insubstantial, and in some cases can if desired be withdrawn longitudinally from the moulded product after curing.

Where required, the tubular member can have fitting therewithin a block (e.g. of wood, preferably hardwood) capable of securely receiving fixing means (e.g. nails, screws, bolts etc.) whereby the moulded product can be secured to another member or structure to be supported thereby; such a block could be pretapped to accept a fixing bolt or screw, e.g. in an internally threaded ferrule secured in the tapping.

In such a case, screw or pin or the like can be positioned in the hole so that it projects above the surface of the curable composition subsequently moulded therearound, being removed after curing; instead of a block, a mating hollow section member, e.g. of metal, preferably predrilled to accept a fixing member or members, can be used in like fashion. Where a plurality of the tubular members need to be disposed end to end to form an extended rib or beam, they may be joined by members which are a sliding matting fit in their ends; by using non-linear such mating members, e.g. angle pieces, T-pieces etc. a variety of interconnecting rib or beam formations may be produced.

Longitudinally tapering ribs or beams can be produced according to the invention by employing strip or sheet of appropriate shape and fold lines.

The tapering tubular members can for example be arranged, with their largest ends adjacent, in a cross- or sun burst-shaped array for the formation of a corresponding composite reinforcement on a panel-e.g. of a water tank or the like.

For the formation of a longitudinally curved rib or beam, e.g. as a spacer or reinforcement on a boat hull, the initially formed tubular member may be cut transversely through its base face at appropriately spaced intervals of its length so that it can be conformed and adhered to the substrate surface. Where the base face is to be secured to a convex surface, then the lateral cuts are made from opposite the base face, and when the base face is secured to the convex substrate the resulting exposed cuts open; in this case, a plain strip can be secured longitudinally over the exposed crest of the tubular member to provide a continuous surface for the application of the curable reinforced composition.

The invention is illustrated, purely by way of example, with reference to the accompanying drawings, in which: Fig. 1 is a plan view of a preferred strip erectable into tubular form for use according to the invention; Fig. 2 is a perspective view of the Fig. 1 strip when erected and secured in its tubular form; Fig. 3 is a perspective view illustrating the tubular member of Fig. 3 used as a male mould for a rib of reinforced plastics material on a substrate surface; Figs. 4 to 8 illustrate various internal supports which may be employed in the tubular member used according to the invention; Fig. 9 is a perspective view illustrating an assembled tubular member and internal support which can be used for the formation of straight or curved ribs and beams;; Figs. 10 and 1 1 are perspective views of a modification of the Fig. 9 arrangement, to be used for the formation respectively of a straight rib and a curved rib: Fig. 12 is a perspective view of an insert which may be used with assemblies of the type shown in Figs. 9to 11; Fig. 13 is a perspective view of another type of insert which can be employed according to the invention; Fig. 14 is an end elevation view of such an insert in position in a tubular member; Fig. 1 5 is a plan view of a strip erectable to tapering tubular form for use according to the invention; Fig. 1 6 is a view from above of a panel reinforcement made using the Fig. 15 embodiment.

In the drawings, like items are designated by like reference numerals.

Figs. 1 and 2 illustrate a preferred strip for use according to the invention, which can be erected into and secured in its predetermined tubular form with particular ease and rapidity. The strip 6 has a single longitudinal score lines 8 and multiple longitudinal score lines 30 so that it is readily folded into a "top hat" section tubular member 2 as shown in Fig. 2. Formed at spaced intervals along the length of the strip portion 13 (which forms the base of the erected tubular member) at or adjacent to its margin with outermost score line 8 are openings 46; the holes or openings 46 appear at the edge of the base 13 of the erected tube adjacent to the overlapping edge portions 12, and provide access to the interior of the tubular member for the anvil of a stapler by means of which the overlapping edge portions may be fixed together.Provision of the holes or openings 46 thus allows great lengths of tubular member to be erected and secured in tubular form very rapidly and efficiently. Staples 7 are preferred for securing together the overlapping portions 12 (it being a particular advantage that the sharp free ends of the applied staples will be within the tubular member rather than being exposed at its exterior), but the holes or openings do of course provide ready access for the application of other types of fixing member if desired. Instead of holes or openings 46, their outline may be defined by lines of weakening of the cardboard or like material of strip 6 (e.g. by partially cutting through the strip), so that the outlined portions can readily be pressed or pushed out from the strip or erected tube to leave the required openings.It is preferred for the openings 46 to be located in the base 13, but they can of course be elsewhere provided they are adjacent to the overlapping edge portions.

The tubular member 2 of Fig. 2 can be used according to the invention in the manner illustrated in Fig. 3. Here the tubular member 2 is disposed with its base 13 secured, usually by adhesive, over the surface of a substrate 5. A curable fibre-or filament-reinforced resin composition is laid up over the exposed surface of the tubular member and into engagement with the adjacent portions of the surface of substrate 5 and allowed to cure to form a reinforcing rib 67 for the substrate. The adhesive used to secure tubular member 2 to substrate 5 is suitably the said curable resin. The illustrated "top hat" shape is the preferred cross sectional shape for tubular members 2, but other cross sections such as square or oblong are possible. The material of the strip 6 is most appropriately cardboard, but other sheet material could be used.The fibrous or filamentary reinforcing material of the curable composition which is moulded over the tubular members is suitably glass, and the curable resin composition may be any of those conventionally employed in glass reinforced plastics (GRP) work; other fibres, e.g. carbon, cellulose acetate, etc.

can be used in addition to and/or instead of glass.

Formation of the reinforced plastics coating over tubular member 2 will normally involve the application of some pressure, and to prevent distortion of the moulding under such pressure, it is preferred to supply internal support for the tubular members 2. Various such supports are illustrated in Figs. 4 to 8. The internal supports are not intended to strengthen the final cured rib or beam, and so may be of inherently flimsy material. Thus the insert shown in Fig. 4 is an "egg box" structure formed of inter-fitting cardboard pieces and shaped to fit within a "tophat" section tubular member of the Fig. 2 type; Fig. 5 shows as an alternative a pylon support structure erected from a flat cardboard sheet and also shaped to fit a "top hat" tubular member. Fig.

6 shows a V-section cardboard support; this could extend the length of tubular member 2, or short sections of it could be spaced along the length of the tubular member. Fig. 7 shows a simple metallic support, erected from a flat soft metal plate, and Fig. 8 a simple wire support. It is also possible to use as internal support a solid block matching the internal profile of the tubular member; this might for example be of expanded polystyrene which in the normal way is not recommended for use in contact with GRP but which is perfectly satisfactory in the present invention since such contact is prevented by the intervening tubular member. The internal support or supports may be disposed where required on the strip or sheet before the latter is erected, or can be inserted longitudinally through the ends of the tubular member. Frequently, such internal supports can be withdrawn once moulding has been finished and used again.

Fig. 9 illustrates a strip 6 of essentially the same configuration as in Fig. 1 erected to its "top hat" tubular form 2. A further carboard strip 1 1 extends the length of strip 6; it has a central portion 15 which is adhered to base portion 13 of strip 6 and is preformed with score lines 9 and lateral slots 55 so that it can be erected into the configuration shown to locate support webs 17 which constitute the internal supports for the erected tubular member. Webs 17 may be of cardboard, plastics, sheet metal, etc. The illustrated tubular member when erected can be used for forming a straight beam or rib as described with reference to Fig. 3 above, or can be used to form a curved rib or beam as described with reference to Fig. 11 below.

Fig. 10 illustrates in assembled form a similar arrangement in which the strip 11 erects to a simple V-section which itself constitutes an internal support, though this strip 11 may also be slotted as in the case of Fig. 9 to accommodate support webs 17. If the Fig. 10 assembly is to be used for forming a straight rib or beam, the procedure is as described with reference to Fig. 3 above. For the formation of a curved rib or beam, however, e.g. on a boat hull, the erected tubular member is cut at appropriate intervals as illustrated in Fig. 1 1 so that it can be curved to conform to the substrate in question. The moulded beam is formed as before, with the base portions 13 being adhered to the substrate, and the reinforced curable plastics composition being moulded over and onto the adjoining substrate as before.For gentle curves, only widely spaced cuts are needed, and there may be no need to fit a support web 17 into every cut segment. For sharper curves, more frequent cuts are necessary and more support webs 17 may be needed, though the latter (and hence slots 15) may be dispensed with altogether if good quality cardboard is chosen for strips 6 and 1 1.

Fig. 12 illustrates another insert which may be provided for a tubular member 2 for use in the present invention. The insert 21 consists of a block 23 (e.g. of hardwood) of cross-section to mate with the inner surface of the upper portion of tubular member 2, and an inverted channel section member secured thereto and having side webs 27 by which the insert is supported on the base 13 of tubular member 2. In the case of embodiments of the type shown in Figs. 9 and 1 1, the side webs 27 may be spaced to fit in slots 55.

In Fig. 12 the tubular member 2 is shown cut away for clarity. The insert 21 can be positioned at an intermediate region along the length of tubular member 2 so that the block 23 can accept screws, bolts, or other fixing means to secure another member (e.g. a cupboard or like fixture) to the cured reinforced plastics rib or beam moulded over tubular member 2.

Fig. 13 shows a strip corresponding to that of Fig. 1 but shaped and provided with fold lines for erection into a longitudinally tapering tubular member. Such tapering tubular members are suitable for use in combination to provide male moulds for the formation of reinforcement structures on panels of vessels such as water tanks and other liquid containers. For example, Fig. 14 illustrates four such tapering tubular members 2, each erected from a strip 6 of the type shown in Fig. 13, arranged in a crosspattern with a cover 29 over the central gap; the crossshaped assembly is adhered to the panel 31 as a male mould over which the durable reinforced plastics composition is moulded in the manner previously described.The distal ends of each tapering tubular member may be feathered into almost flush relationship to the panel so that the resulting moulding is of good appearance and provides optimum reinforcement for the panel.

Figs. 15 and 16 illustrate another type of insert for the tubular members 2 which can be provided to allow for the attachment to the finished rib or beam of a fixture. The insert has a bar 35 which is inserted transversely across the erected tubular member 2, slots or corresponding press-out portions being provided in the corresponding portions of the strip 6 to allow for this. The bar 35 is of a length to project outwards slightly from the side walls of the erected tubular member 2. The other portion of the insert is a stud 37 having a shank slotted at its lower end to mate with bar 35 and having at its other end a head 41 from which a threaded axial bore extends for accommodating a bolt or screw 49, or as illustrated in Fig. 16. Fig.

16 illustrates a modification of the Figs. 1 and 2 type of tubular member, in which the overlapping portions of the strip constitute the base of the tubular member. When the tubular member is moulded over with the reinforced resin composition, the bar 35 is securely held by the cured composition, as is the lead 41 there thus being provided means for the secure attachment to the finished rib or beam of a fixture or other attachment. In a modification, the bar 35 is dispensed with, and an unslotted stud 37 is located instead in a complementary bore in the block 23 of an insert of the type shown in Fig. 12.

The shaft of the stud, and the bore in block 23, will normally have a flat face or be polygonal so as to prevent rotation of the stud on engagement with its bolt or screw.

The tapering tubular members formed from strips as in Fig. 13 can be provided with corresponding internal support(s) as in other described embodiments but of appropriate graded or varying size(s).

Claims (14)

Claims

1. A method of forming a rib or beam on a substrate, the method comprising providing a strip or sheet formed to be erectable into predetermined tubular form having a base surface, erecting it into and securing it in the said predetermined tubular form, securing the base surface of the resulting tubular member to the substrate, and then moulding a curable reinforced plastics composition over the exposed surface of the tubular member and into engagement with the adjacent surface portions of the substrate, and causing or allowing the composition to cure to form the rib or beam.

2. A method according to claim 1 including the step of providing internal support for the erected tubular member.

3. A method according to claim 1 or 2 for forming a curved rib or beam, including the step of cutting the erected tubular member transversely at spaced regions along its length to allow it to be conformed to the curved profile of the substrate.

4. A method of forming a rib or beam on a substrate, the method being substantially as hereinbefore described.

5. A kit for forming a rib or beam on a substrate, the kit comprising a strip or sheet formed to be erectable into predetermined tubular form having a base surface, components for forming a liquid curable resin composition, and reinforcing material for incorporation in said material.

6. A kit according to claim 5 including at least one member for providing internal support for said tubular member.

7. A kit according to claim 6 wherein said internal support is substantially as hereinbefore described with reference to any of Figs. 4 to 12.

8. A kit according to any of claims 5 to 7 including at least one insert for incorporation in the tubular member to provide a point for attachment of a fixture to the completed rib or beam.

9. A kit according to claim 8 wherein the insert is substantially as hereinbefore described with reference to Fig. 12 or to Figs. 15 and 16.

10. A kit according to claim 5 and substantially as hereinbefore described.

11. A rib or beam of cured reinforced plastics, the rib or beam being substantially as hereinbefore described with reference to any Figure of the accompanying drawings.

12. A method according to claim 1, 2, or 3 wherein the strip or sheet is erectable to predetermined longitudinally tapering tubular form.

13. A kit according to any of claims 5 to 9 wherein the strip or sheet is erectable into predetermined longitudinally tapering form.

14. A kit according to any of claims 5 to 9 and 13 wherein the strip or sheet is in lay flat tubular form.