AU2006202470A1 - Board for gliding having a deck with a sandwich structure having an elastic core - Google Patents

Description

S&F Ref: 765760

AUSTRALIA

PATENTS ACT 1990 COMPLETE SPECIFICATION FOR A STANDARD PATENT Name and Address of Applicant: Actual Inventor(s): Address for Service: Invention Title: Salomon of Lieudit La Ravoire, F-74370, Metz- Tessy, France Anthony Bert Spruson Ferguson St Martins Tower Level 31 Market Street Sydney NSW 2000 (CCN 3710000177) Board for gliding having a deck with a sandwich structure having an elastic core The following statement is a full description of this invention, including the best method of performing it known to me/us:- 5845c BOARD FOR GLIDING HAVING A DECK WITH A SANDWICH STRUCTURE HAVING AN ELASTIC CORE Technical Field The invention relates to the field of boards for gliding on water such as surfboards and sailboards.

Background of the Invention In the traditional design, the surfboard is made of a slab of foam plastic, particularly of stiff polyurethane foam, which is formed in a mould. The foam plastic slab is shaped by planing and sanding to give it a personal touch and to form the core of the board. This core is then lined with a resin-impregnated glass fibre envelope which forms a reinforcing outer shell and gives the board its final form and mechanical strength. A decoration and glazing give the board its final appearance.

In certain cases the core is longitudinally cut into two parts which are then glued is on a wood lath reinforcing its structure.

One of the shortcomings of this technical design is given by the final weight of the board. The foam plastic is actually relatively dense, with the volume weight typically amounting to about 50 kg/m 3 It is not possible to reduce a priori the density of the foam plastic without impairing the mechanical characteristics of the board.

In the field of "bodyboard" slabs, the board is made basically of an elastic foam plastic (possibly combining several layers of different densities and characteristics) without an envelope of very good mechanical characteristics. In this case the boards are provided with a lower layer of thermoplastic material in order to provide better gliding on water. However, these boards are relatively flexible because the user must be able to deform them during their use in order to obtain optimal steering. By contrast to surfboards and sailboards, on which the user keeps himself on top, the bodyboard slabs must not sustain large loads because the user uses them while he is spread out on the surface of the water and only his breast is supported by the slab.

In an other technical design relating to the field of sailboards, one uses a board of rigid foam plastic of relatively low density (for example, an expanded polystyrene foam of 18 kg/m 3 which is worked to obtain the shape or which is moulded directly in the form of the board's core. The core is covered with an outer envelope which can comprise a skin of resin-impregnated glass fibre and/or a foil of thermoplastic material and/or a sandwich structure. This design makes it possible to obtain an advantage in regard to the total weight while maintaining good rigidity, namely when one uses an envelope with a [R:\LIBLL] I18608 doc z sandwich structure, a structure comprising a low-density layer (generally foamed PVC or extruded polystyrene) enclosed between two finer layers with very good mechanical characteristics (particularly resin-impregnated fibres). Resorting to sandwich structures, such a design makes it possible to obtain rigid boards with potential performance characteristics, but always at the expense of poor comfort and reduced steering capability.

In other techniques, the board consists of a central core made of a first cellular material which is covered by a layer of rigid cellular material of greater density and resistance, which, in turn, is covered by an outer skin (thermoplastic foil or layer of resinembedded fibres, see WO-82/04023 or DE-33.11.734).

It is also known to make hollow boards with an envelope having sandwich structure. For example, one can use two half-shells which are then assembled or one can prepare the assembly in a closed mould with an internal bladder which is inflated to be able to apply the sandwich structure to the walls of the mould.

In an other list, it is known to make boards with a rigid inner structure, covered by an outer layer of flexible foam plastic which determines the outer shape of the board (see US-3.543.315 or US-5.489.228). These boards are generally very comfortable in regard to their steering, but their weight is large and the flexibility of the outer envelope does not provide good results in regard to response and precision of the steering of the board. As a matter of fact, the layer of flexible foam plastic is covered only with a plastic film or a flexible coating without significant mechanical resistance, with the only goal of protecting the flexible foam plastic against abrasion and of improving the gliding.

Further, it has been known to provide boards which have different structures on their submerged portion and their deck. Document FR-2.787.088, proposes a board having a core of foam plastic covered by an envelope. The envelope on the deck has a rigid sandwich structure, whereas the envelope is a simple resin-impregnated fiber layer on the submerged portion. According to FR-2.612.974, the submerged portion of the board is lined with a fine layer of elastic material to provide it with shock-absorbing properties. On the other hand, according to document DE-32.06.334 it is the deck of the board which is covered with a layer of elastic material. In the latter two cases, the layers of elastic material are directly exposed to the outside.

Document DE-197.41.917 describes various designs in which the envelope of the board comprises a layer of resin-impregnated fibers connected to a layer of cushioning material. Several options are considered but it is always provided that the cushioning layer is situated on the outside relative to the resin-impregnated fiber layer. Further, the [RA\LIBLL]IS608 doc Izv cushioning layer can be provided only on the deck or also on the deck and the submerged portion. This document considers the utilisation of a sandwich-structure envelope.

It is therefore desirable to provide a design for producing boards for gliding, particularly for surfboarding or sailboarding, which is especially optimised to ensure production at low cost, a low final weight of the board, an overall rigidity sufficient for obtaining adequate performance, and a definite comfort of utilisation without concessions in regard to precision in steering the board or in regard to its solidity.

Object of the Invention It is the object of the present invention to substantially overcome or at least ameliorate one or more of the disadvantages of the prior art or to meet the above desire.

Summary of the Invention Accordingly, the present invention provides a board for gliding on water comprising a core covered by an outer envelope forming a deck and a submerged portion, wherein the outer envelope comprises at least a deck portion and a submerged hull portion, wherein at least the deck portion of the envelope has a sandwich structure consisting of a central layer of low density arranged between two finer layers with very good mechanical characteristics, wherein said fine layers of very good mechanical characteristics comprise resin-impregnated fiber sheets, and wherein the central lowdensity layer of the sandwich structure of the deck portion comprises a flexible and elastic cellular material.

In a preferred embodiment of the invention, there is provided a board for gliding on water, comprising a core covered with an outer envelope forming a deck and a submerged portion, wherein the outer envelope has at least a deck portion and a submerged portion, the two made as sandwich structures formed for each of the portions by at least one central low-density layer between two finer layers with very good mechanical characteristics, wherein the layers of very good mechanical characteristics comprise resin-impregnated fiber sheets, wherein the central low-density layer of the submerged portion is made of a rigid cellular material, whereas the central low-density layer of the deck portion consists of a flexible and elastic cellular material.

Brief Description of the Drawings Preferred embodiments of the present invention will now be described, by way of an example only, with reference to the accompanying drawings wherein: Figure 1 is a schematic view from above of the board according to an embodiment of the invention; [R\LIBLL18608 doc z Figure 2 shows a schematic transverse section along line II-II of the board of Figure 1; Figure 3 is a partial enlarged and exploded view of Figure 2; Figure 4 is a schematic view of a transverse section illustrating a manner of reinforcing the rigidity.

Figure 1 shows the general outer shape of a board for gliding on water 10, for example, a surfboard. Figure 2 shows an embodiment of the invention in which the board has a core 14 arranged in the interior of outer envelope 12. In well-known fashion, the outer envelope 12 forms in its upper part the deck 16 of the board on which the user has to keep himself, whereas in the lower part, the submerged portion 18 is supported by the water. The peripheral outer edge of the outer envelope defines the rails of the board. As a matter of fact, this outer envelope defines in sealing fashion an interior space of the board which is completely or partially filled by the core 14.

For the core one can consider the use of an expanded polystyrene of a plastic of very low density, for example with an apparent volume weight of less than 25 kg/m 3 but also of equal to, or less, than 18 kg/m 3 The core 14 can also have local reinforcements of a particularly resistant material, either over the entire height of the internal space confined by the envelope or only over part of that height. An example of such a core will be described below with reference to Figure 4.

In the embodiment illustrated, the core 14 completely fills the interior of the board. However, there can also be provided recesses in a way such that in the interior of the outer envelope 12, there are hollow inner zones, for example at the forward portion of the board, which means, in a zone in which the user usually seeks but little support. The presence of hollows has a favourable influence on the weight of the board and their distribution determines the dynamic moment of inertia of the board, with this moment of inertia affecting its behaviour on the water, particularly its response to different loads and changes in the direction imposed by the user.

For the sake of simplicity and economy, the core 14 illustrated in the figures is a single block and is made of a single material. One could provide a core composed of various elements, possibly made of different materials.

Furthermore, the core could be perforated with weight-reducing holes. Similar processes for making the core lighter, such as described in documents FR-2.820.712, FR- 2.820.713, and FR-2.820.714, can be advantageously employed within the scope of the present invention.

[R\LIBI.L]J 18608doc:lzv In this embodiment of the invention, the two parts (deck and submerged portion) of the envelope are of a sandwich design in which the layer of low-density material forming the core sections 24, 25 of the sandwich structure is enclosed between two layers, inner layer 26 and outer layer 28, of reinforcing material which form the plates of the sandwich and comprise, for example, sheets of fibers embedded in resin, for example, an epoxy resin. The type of the fibers (glass, carbon fibers, aramid fibers. etc.) can be identical or differ for the inner layer and the outer layer. They may also be different for the submerged portion and the deck, for example, the inner layer of the deck could be made of aramid fibers, whereas the inner layer of the submerged portion could consist of carbon fibers. Similarly, the fibers of the sheets can be woven or non-woven, can be monodirectional or multidirectional. In the simplest and most economic designs, the fiber sheets are made of a glass fiber fabric.

In the improved embodiment of the invention, the two sections, deck and submerged part of the envelope, differ in the type of material forming the core sections 24, 25 of the sandwich structure. In the submerged portion, the layer 25 of low-density material is formed by one or more materials specified as "rigid", whereas in the deck portion the layer 24 of low-density material comprises, according the invention, at least one part formed by a flexible cellular material.

Of course, the low-density materials are preferably cellular materials, and, more particularly, foam-plastic materials.

Those skilled in the art usually classify plastic foam materials as elastic foams on the one hand and rigid foams, on the other.

The rigid foam plastics have low elasticity and this means that when the compression load exceeds a certain value, they deform by collapsing, irreversibly or only slightly reversibly. Among these rigid foam plastics there are the polyurethane foams and the extruded polystyrene foams or expanded polystyrene foams which are generally used in the form of foam plastic sheets to render the cores of the traditional surfboards.

Similarly, certain PVC foam plastics or polyimide foams generally used as cores of sandwich structures are considered rigid materials. Although termed rigid, these foam plastics when used in very-low density varieties can be rather easily compressed (and then appear softened), but they have a very low elasticity.

Among the flexible cellular materials, there are known flexible foam plastics with elastic characteristics such as expanded polyolefin foam plastics, particularly those of polypropylene or polyethylene. In the case of expanded polypropylene foam plastics, one can, for example, use varieties with an apparent volume weight between 20 and 100 [I R:\LIBLL] 8608.doc Izv kg/m 3 These materials usually have a 25% deformation limit under compression loads of the order of 100 to 600 kPa. The main elements of choice in regard to materials are resistance to compression, but even more the capability of elastic deformation (the material should preferably return to its initial shape after a compression of the order of as well as its capability of restitution of the energy absorbed during the compression.

Of course, other materials can be used. Thus, for the submerged portion the rigid foam plastic 25 can be replaced by a honeycomb structure or by a layer of light wood.

Using a rigid core 25 for the sandwich structure of the submerged portion makes it possible to obtain great rigidity of the submerged portion which is favourable for good acceleration and a very high precision in steering the board. In less elaborate embodiments of the invention, the submerged portion of the envelope may have an other structure. There can be a simple resin-impregnated fiber layer or an intermediate layer of a light material and a rigid material (rigid foam plastic, light wood, etc. and this covered by a layer of resin-impregnated fibers.

Using a flexible material for forming the core 24 of the sandwich structure of the deck is particularly innovative. As a matter of fact, by selecting high rigidity for this flexible material, one could make good use of the exceptional rigidity/weight ratio of the sandwich structure, and all this while introducing on the level of the deck a surface elasticity which is particularly welcome in regard to comfort and ability of steering the board.

This results from the fact that the outer skin of the resin-impregnated fibers, which have a high intrinsic elasticity, will be deformed by the weight of the user without causing collapse of the material of the core 24 which is also elastic and then can return into position while giving back a large part of the stored energy. The outer skin 28 is then subjected to bending and, at the same time, experiences traction on its plane, like a trampoline. When stretched in this way, the outer skin 28 of composite material returns energy to a greater measure than the simple elastic return of an elastic material which could be arranged on the deck of the board and which is vertically compressed. In a comparison, the "trampoline" effect with a strong elastic component can be compared with a simple "mattress" effect which is basically dampening and which therefore tends to return only a small part of the energy transferred. The trampoline makes the steering of the board much livelier.

Of course, this effect of deformation/restitution of the outer skin 28 of the sandwich is completely reversible (at least to a certain limit which can be determined, for [R \LIBLLI18608 doc Izv example, by varying the thickness and the rigidity of the flexible elastic material forming

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Othe core 24 of the sandwich structure) and this happens without causing a significant deformation of the core 14 because under the flexible and elastic layer there are resin- ;impregnated fiber layers 26. This, particularly because of the intrinsic mechanical resistance, makes it possible to spread over a large surface the transferred stress.

In addition to the advantage in terms of liveliness, the sandwich design with an Selastic core enables the deck to resist in a better way the shocks and the effects of downward bending. In order to enhance the trampoline effect, the resin of the outer skin S(for example, an epoxy resin) may be mixed with compounds improving the flexibility.

D 10 In the example illustrated, one can see that the layer 24 of flexible foam material, which forms the core of the sandwich structure of the deck, extends to the rear along the lateral edges of the board. This contributes noticeably to a higher impact resistance of the structure in a particularly exposed zone. Of course, one could also think that this is the sandwich structure 25 of the submerged portion which extends along the lateral edges, that the two structures could join at the point of greatest width, or also that the lateral edges have a proper structure.

Various processes can be contemplated for the production of a board according to the invention.

The outer envelope 12 can be made in the form of two prefabricated half-shells which form the deck and the submerged portion, with the half-shells being joined with each other, for example, by adhesive bonding along their plane of junction in order to obtain a sealed outer envelope.

In a version, these two half-shells cannot be assembled before the outer reinforcing layer has been applied onto the layer forming the core of the sandwich. Such a process is similar to that described in document WO-02/10011 to which reference is conveniently made, and has the advantage to provide the opportunity of redoing the layer forming the core of the sandwich after assembly of the two half-shells but before the outer layers of the sandwich are applied, and this in order to give a personal touch to the shape of the board, if desired.

According to an other production method, the set of components can be assembled and shaped under pressure in a mould, well in accordance with the technique which is customarily employed for manufacturing sailboard gliders of the sandwich type.

In the example shown in the figures (see Figure the outer envelope 12 has also an external protection in the form of a foil 30 of a thermoplastically moulded material. This protective layer 30 is, for example, translucent and can be decorated. The [R:\LIBLL 18608.doc Izv decoration is advantageously applied to the foil's surface facing the interior and can be produced, for example, by silk screen printing or sublimation. One can also consider incorporating a decorative element between the outer skin 28 and the protective foil. The protective foil is, for example, made of a material which is a mixture of ABS and polyurethane and has a thickness of the order of 0.3 mm. The protective foils could be different for the deck and the submerged portion. One could also think of applying this protective layer only to one side of the board, for example, the deck.

Figure 4 shows a form of the reinforcement 32. This reinforcing element 32 consists simply of a sheet of resin-impregnated fibers and is folded back upon itself to 1o form a T the vertical part 34 of which is inserted in a groove 36 provided in the core 14, with the horizontal part 38 bearing against the upper surface of the core 14. To this end, one provides in the core a straight groove 36 which is basically perpendicular to the outer surface of the core. After that, the sheet of resin-impregnated fibers (not yet polymerised and therefore still flexible) is bent at two points and inserted in the bottom of the groove 36. The sheet sections which go the outside are then folded down on the inner side of the core. Once the resin has polymerised, the reinforcement 32 forms a rigid T profile which is integral with the core 14. The vertical part 34 of the T renders a very good bending strength, whereas the horizontal part 38 forms a kind of plate which spreads the pressure applied locally through outer envelope 12 to core 14. This reinforcement 32 is also conveniently a side of the board's deck because it reinforces the core where strong pressure is applied as a consequence of supporting the user. Figure 1 shows a possible arrangement with two reinforcing elements situated on the deck, each on a median longitudinal axis of the board. Once can also use such a reinforcement on the submerged side to make full use of its bending strength.

In the example of Figure 4, the reinforcing element 32 is set on the uncoated core 14. However, in order to facilitate the work, the reinforcing element is preferably placed after lining the core with the inner skin 26. The main difference is that the horizontal part 38 of the reinforcing T is then arranged between the inner skin 26 and the low-density layer 24, The design according to the invention makes it possible to produce a board which is a perfect compromise between the capability of precision steering, comfort and performance, and all this with a completely industrial manufacture allowing relatively low production costs.

[RA\LIBLLI18608doc:lzv

Claims (14)

1. A board for gliding on water comprising a core covered by an outer envelope forming a deck and a submerged portion, wherein the outer envelope comprises at least a deck portion and a submerged hull portion, wherein at least the deck portion of the envelope has a sandwich structure consisting of a central layer of low density arranged between two finer layers with very good mechanical characteristics, wherein said finer layers of very good mechanical characteristics comprise resin-impregnated fiber sheets, and wherein the central low-density layer of the sandwich structure of the deck portion comprises a flexible and elastic cellular material.

2. The board according to Claim 1, wherein the central low-density layer of the deck portion of the envelope consists of a polyolefin foam plastic.

3. The board according to Claim 2, wherein the central low-density layer of the deck portion of the envelope consists of a polypropylene foam plastic.

4. The board according to any one of the preceding claims, wherein the central low-density layer of the deck portion of the envelope has a 25% deformation limit under compression loads of the order of 100 to 600 kPa.

The board according to any one of the preceding claims, wherein the central low-density layer of the deck portion of the envelope returns to its initial form after a compression of the order of

6. The board according to any one of the preceding claims, wherein the sandwich structure of the deck portion is extended to the lower part along the lateral edges of the board.

7. The board according to any one of the preceding claims, wherein the sandwich structure of the deck portion of the envelope is covered with a protective layer of a thermoplastically moulded material.

8. The board according to Claim 7, wherein the protective layer is transparent and decorated on its inner surface.

9. The board according to any one of the preceding claims, wherein the submerged portion of the outer envelope has a sandwich structure consisting of at least a central layer of low density arranged between two finer layers with very good mechanical characteristics, wherein the layers with very good mechanical characteristics consist of resin-impregnated fiber sheets, and wherein the central low-density layer of the submerged portion is made of a rigid material. [R \LIBLL]18608 doc:lzv e

10. The board according to any one of Claims 1 to 8, wherein the O 0submerged portion of the outer envelope comprises at least one layer of resin-impregnated fibers which overlay an intermediate layer of rigid materials.

S11. The board according to any one of the preceding claims, wherein the 0 5 core is made of expanded polystyrene foam plastic.

12. The board according to any one of the preceding claims, wherein the core has recesses.

13. The board according to any one of the preceding claims, wherein the entire board is covered with a protective layer of a thermoplastically moulded material.

14. The board according to Claim 12, wherein the protective layer is transparent and decorated on its inner surface. A board for gliding on water substantially as hereinbefore described with reference to the accompanying drawings. Dated 9 June 2006 Salomon S.A. Patent Attorneys for the Applicant/Nominated Person SPRUSON FERGUSON [R \LIBLL 18608.doc lzv