EP1475303B1 - Surfboard and method for its production - Google Patents

Abstract

The sub-assembly comprises a hollow inner shell (7) made from resin-impregnated fibres with optional reinforcement or support, covered with a layer (8) of a high-density foam which can be reinforced locally by a plastic or cardboard honeycomb structure. The shell has a wall thickness of 0.1 - 2 mm; the foam has a density of 50 - 70 kg/cu m and is 3 - 20mm thick.

Description

The invention relates to a subassembly provided for producing a float glide on water including a surf float.

It also relates to a method of manufacturing such a subset and a float made from the subset in question.

In a traditional way, a surf float is made from a foam roll, in particular polyurethane foam, which is formed in a mold. The foam roll is machined by planing and sanding to a small thickness to locally customize its shape and it is coated with a resin-impregnated fiberglass envelope that forms an outer reinforcing shell and gives the float its final shape. A decoration and an icing give the float its final appearance.

In some cases, the foam cake is cut longitudinally into two parts which are then glued against a wooden slat which strengthens its structure and imposes a predetermined longitudinal camber.

The disadvantage of such a construction technique is the weight of the float in the end. Indeed, the foam is relatively dense, typically its density is 50kg / m3. And it is not possible in principle to reduce the density of the foam without affecting the mechanical characteristics of the float.

According to another technique of construction from windsurfing, we start from a relatively low density foam roll that is machined so as to shape it. This bread is covered with a fiberglass skin impregnated with resin. There is reported around this subset a foam envelope of higher density. Resin-impregnated glass fiber plies are then applied to form the outer shell.

Such a construction method allows a weight gain of about 20% or more while keeping a good rigidity under the feet. However, its implementation is relatively complex. In addition the central foam roll is generally made of polystyrene foam. This material has the defect of taking water. It happens that during its existence the float is struck against a reef or a rock. If the outer shell is damaged, there is the risk of water infiltration, the water weighing the float and being particularly difficult to evacuate.

Finally, it is known to make hollow floats with sandwich skins. Or two half-shells are made which are then assembled together, or the whole is carried out in a closed mold with an internal bladder that is inflated to push and apply the sandwich skins against the walls of the mold.

This manufacturing technique makes it possible to produce light boards. However, it is not possible to customize the shape of the float. In this case the shape of the outer shell depends exclusively on the shape of the mold.

The document US 3514798 which is considered to be the closest state of the art, describes a gliding float and its manufacturing process.

An object of the invention is to provide an improved subassembly, which allows to achieve lighter surfboard floats while retaining a customizable shape, or more bulky for an equal weight.

This object is achieved by a structural subassembly which comprises according to the invention a hollow internal shell, which is covered with a foam envelope capable of being machined.

The float is characterized in that it comprises the previously defined assembly covered with at least one sheet of resin impregnated fibers.

The invention will be better understood by reference to the description below and attached drawings attached thereto.

The figure 1 is a top view of a surf float.

the figure 2 is a side view of the float of the figure 1 .

The figure 3 is a cross-sectional view of a float constructed in accordance with the prior art.

The figure 4 represents, in cross section, the structural subset according to a first embodiment of the invention.

The figure 5 is a longitudinal sectional view of the float made from the subset of the figure 4 .

The figure 6 represents the same float in cross section.

The figure 7, 8 and 9 are cross-sectional views illustrating three alternative embodiments of the invention.

The Figures 10 to 13 illustrate in cross section a fourth embodiment of the invention in which the structural subassembly is made in the form of two half-shells.

Referring to Figures 1 and 2 , in known manner, a surf float is an elongated board with a central portion 2, a tapered front spatula and slightly raised 3, and a rear heel 4 slightly raised and with a decreased width.

In a traditional way, as represented by the figure 3 , the float is made from a foam roll 5, typically polyurethane foam density 50 kg / m3, which is covered with a sheet 6 of resin-coated fibers. Usually, the foam bread is made in mold, and it is available in different models of length, width, volume and a variable camber. Once chosen by the manufacturer, the foam cake is put into the desired final shape by local planing on a small thickness, and only then, it receives its outer coating. This coating makes it possible to increase the mechanical characteristics of the foam, and also to protect the foam bread.

The figures 4 and 5 show, respectively in cross section and in longitudinal section, a structural subassembly of the float according to the invention, that is to say the subset which is located under the outer coating of the final float.

According to this first embodiment of the invention, the subassembly is formed by an internal shell 7 which is coated with a foam envelope 8.

The inner shell is hollow. It is a structural element for example made of glass fibers, carbon or other synthetic material impregnated with resin, polyester resin, epoxy or other.

For example, the inner shell is made with a thickness of between 0.15 and 0.2 millimeters, or between 0.10 and 0.25 millimeters, or even more depending on the intended use of the float and the type of resin used. In some cases and depending on the material used, the thickness can reach 1 to 2 millimeters.

The inner shell can be made according to different techniques. For example it is formed around a central core of polystyrene beads glued with vinyl glue which is then dissolved in hot water. Other types of dissolvable mandrel or an inflatable bladder can be used.

According to another embodiment, the shell is made of several parts assembled together. For example the shell can be made from two half-shells (or half-shells) which fit into one another. The two parts are assembled by gluing or any other suitable means. Other possibilities still exist.

The shell 7 may also be constructed of other materials than resin-impregnated fibers, for example a thermoplastic material, thermoplastic filled with fibers, fibers sprayed with a polyester matrix, stamped metal or any other material with high elastic modulus .

The shell is coated with an envelope 8. The envelope is foam, but different types of foams can be used. For example, a relatively dense PVC foam with a density of 50 to 70 kg / m 3 can be used. It is also possible to use less dense foams, for example polyurethane foams of about 50 kg / m 3. It is also possible to use polystyrene foams (extruded or expanded) from 30 to 50 kg / m 3, or polyetherimide foams or any other watertight foam.

The thickness of the envelope is determined to allow subsequent machining of this subassembly on this small thickness while finally having a strong and lightweight subassembly. For example, the thickness is between 3 and 15 millimeters or even 20 millimeters. Optionally, a greater thickness may be provided along the side and front / rear edges of the subassembly, and lower on the top and bottom. It can also provide different thicknesses on the top and bottom, on the front and back.

To achieve the foam envelope, it sticks foam plates that are shaped to the shape of the shell by applying pressure, for example under-vacuum leaving the shell of the shell at atmospheric pressure so not to deform this shell. An alternative is to place the shell in the center of a mold in which the foam is injected, or to sink or spray this foam on the shell and let it expand in the open air. The polymerization of the foam ensures its superficial cohesion with the shell. A primer can be applied to the surface of the shell to improve performance.

The subassembly thus produced has the advantage of being lightweight and resistant. Indeed, as the inner shell 7 is hollow, we obtain a significant saving in weight compared to a traditional foam bread.

It is more resistant than traditional foam bread due to its structure, with the inner shell and the relatively dense foam envelope. The two elements intervene in a complementary way, the shell by its own resistance and by the effect of closed shell, and the foam by its own resistance and the effect of spreading of the stresses that it produces on the surface of the shell and the role of nucleus in the final sandwich after adding the last superficial layer.

In addition, thanks to the previously mentioned weight gain, one can choose a foam more resistant and denser than a traditional foam while maintaining a weight significantly lower than that of a traditional float.

In addition, thanks to the low thickness of foam used and the support of the shell, it is possible to reinforce locally the surface under the feet by the addition of a honeycomb structure (plastic, cardboard, aluminum ...) at the time of making the foam.

Other filling materials, such as wood, or all materials with a density of less than 1, could also be used.

The subassembly can be machined in the same way as a traditional foam roll, according to the desire of the maker, provided that the machining thickness remains less than the thickness of the foam.

As for traditional breads, the invention provides for making several models of structural subassemblies with a length, a width a volume and a variable camber. However, the same model of shell can be used for several board models, and play on the shape and thickness of the foam envelope to obtain the desired final shapes.

Finally, once shaped, the structural subassembly with its machined foam layer 8 'is intended to be covered with a ply 9 of glass fibers or other resin-coated, and to receive the finishing operations of the same way as for a traditional float. This is represented in figure 6 .

During its use, since the inner shell is hollow, a user will have less problem to evacuate the water which will have infiltrated if necessary following a shock thanks in particular to the incorporation of a drain screw. In this regard, it is possible to provide inside the shell an inflated bladder which reduces the penetration of water inside the shell. This bladder can even be inflated with a gas lighter than air, for example helium, to further lighten the structure.

The figure 7 relates to an alternative embodiment of the invention. According to this variant, the inner shell 10 is reinforced by a central partition 11. Such a partition is used routinely, particularly for long floats, to give them a specific camber and better longitudinal rigidity.

In this case, the central partition 11 is for example foam or wood. It extends over the length of the shell. The shell 10 is formed around this partition. Optionally, the partition is lined with two layers 13 and 14 of resin impregnated fibers, which are connected continuously with the wall of the shell.

As in the previous case, the shell 10 is coated with a foam envelope 12.

The figure 8 is relative to another variant, wherein the upper wall of the shell 15 is supported by a foam plate 16 previously curved.

To make the subassembly, for example, the plate 16 is shaped by thermoforming or any other appropriate technique.

First of all, the bottom wall of the shell is made, on which plate 16 is put in place.

Then, the shaping of the shell is completed by covering the plate 16 with the sheet of fiber impregnated with resin, then the foam envelope 17 is formed.

This plate 16 improves the resistance to depression of the upper part of the subassembly, that is to say under the feet of the surfer.

According to the variant illustrated in figure 9 , the plate 18 is in two parts 18a, 18b which meet at a central partition 19 of the same nature as the partition 11. As in the previous case, the shell 20 is closed above the plate 18 and the shell 21 is formed around the shell 20.

We have illustrated on Figures 10 to 13 yet another embodiment of the invention in which the structural subassembly is made from two assembled half-shells. The subassembly can thus be formed of an upper half-shell 22, which will form the bridge of the final float, and a lower half-shell 24 which will form the hull. Each half-shell is formed of a foam plate 26, 28 which is first thermoformed in a mold and then covered, on an inner face 30, 32, with at least one layer of fabric impregnated with resin. Advantageously, the laminating operation of the inner face 30, 32 of the half-shells 22, 24 will be performed under vacuum while the previously thermoformed foam plate 26, 28 is still in the thermoforming mold, so that the layer of Resin-coated fabric hardens on the blister plate while it is still pressed against the mold. This ensures the best shape of the half-shell before assembly.

When the two half-shells 22, 24 are joined to one another, for example by gluing, the rigid internal shell 7, which is formed by the layers of resin coated fabrics arranged on the internal faces of the half-shells, and secondly the outer envelope of foam capable of being machined 8. The foams used are for example extruded polystyrene foam plates with a density of the order of 30 to 50 kg / m3.

For the implementation of this variant, it may be advantageous to provide that one of the half-shells, for example the lower half-shell 24, is also laminated on its face. outside 34 before assembling the two half-shells. The half-shell thus laminated on its two faces 32, 34 is then particularly rigid during assembly with the other half-shell, which makes it possible to better control the precision of the assembly, and therefore the precision of the shape. of the subset. Of course, the foam envelope covering the shell is then no longer able to be machined over its entire area. Indeed, one of the faces being already stratified at the time of assembly, the geometry of this face can not be deeply modified. However, it has been found that, in order to appreciably modify the final behavior of the gliding float, it is often enough to modify the geometry of the lateral edges of the float (generally called the float rails). However this geometry can be modified even if one of the external faces of the float (for example the lower face) is already stratified.

In the example shown on the Figures 10 to 13 it can be seen that the two half-shells are not symmetrical. Indeed, it can be seen that the lower half-shell 24 does not have lateral flanges. When formatted, the plate is bent in the longitudinal direction (which is not visible in the drawings) to follow the curve of longitudinal arch (sometimes called "rocker" or "scoop" curve). It could also be curved in the transverse direction, for example to form a hull V or double concave, but in the example shown the lower half-shell has no transverse curvature. In this case, since the deformation of the foam plate with respect to its initial plane state is relatively low, the shaping of the plate can be done without thermoforming, simply by pressing the plate against the mold by depression at the moment of stratification. After curing the resin, the stiffness of the resin-coated fabric is sufficient to maintain the plate at the desired shape of the half-shell.

On the contrary, the upper half-shell 22 is thermoformed so as to be curved longitudinally, but also transversely to form lateral flanges 36 curved downwards. According to the invention the inner faces (that is to say the lower face 30 of the upper half-shell 22 and the upper face 32 of the lower half-shell 24) are laminated with one or more layers of fiber fabrics. impregnated with thermosetting resin. As can be seen at figure 10 , the lower face 34 of the lower half-shell 24 is also laminated, before assembling the two half-shells.

As can be seen at figure 11 , the assembly of the two half-shells is obtained by gluing the lower edge of the lateral flanges 36 of the upper half-shell 22 against the upper face 32 of the lower half-shell 24. The glue will be chosen so as not to be too difficult to machine, that is to say so as not to create a hard spot in the foam component of the side edge of the subassembly.

With this construction, we see at the figure 12 (which illustrates in more detail the lateral edge of the subassembly just after the assembly) that the greater part in height of the lateral edge 38 of the structural assembly is formed by the lateral flanges 36 of the upper half-shell whose outer face 40 is made of foam. The bottom part of these edges side is formed by the side edge of the lower half-shell which has a thickness of framed foam 28 (top and bottom) by two thicknesses of resin-impregnated fabrics 32, 34. As the fabric thicknesses 32, 34 are very small, they do not form an obstacle to the machining of the lateral edges. So, on the figure 13 it can be seen that the geometry of the lateral edge 38 of the structural subassembly has been modified over the entire height of the lateral edge 38, for example by planing and sanding.

However, in a variant (not shown), it may be ensured that the peripheral portion of the upper face 32 of the lower half-shell 24 is free from lamination so that the lateral flanges 36 of the upper half-shell 22 are in abutment against the foam 28, this to ensure a better continuity of the material forming the side edge 38 which then consists of foam.

The lamination of the outer surface, in this case the lower surface 34 of the lower half-shell, can be complete (as illustrated). It can also concern only a part of the surface, for example the central part to preserve perfect machinability of the lateral edge 38.

With this construction, the precise assembly of the two half-shells is facilitated by the high rigidity of the lower half-shell, and the sub-assembly remains capable of being machined over its entire upper surface and on its lateral edges, which leaves a great capacity for customizing the subset. Once customized, the structural subassembly is covered with an outer layer of resin impregnated fibers. Depending on the case, it will be possible to also cover the already stratified external surface 34 of the subassembly with this outer layer, to increase the rigidity and the strength of the float, or on the contrary choose not to cover this already laminated surface 34, this to limit the weight of the float.

Of course, in the case where it is desired to privilege the possibility of customizing the hull of the float, one could predict that the half-shell laminated on both sides is the upper half-hull, the lower half-hull being then In both cases, the subassembly thus produced is a subassembly which, in the sense of the invention, comprises a hollow and rigid internal shell, and a foam envelope capable of being machined. which completely covers this inner shell. Optionally a part of this envelope (which one does not wish to change the geometry, for example the upper face of the upper half-shell or the lower face of the lower half-shell), may be covered with a rigid outer layer.

As in the case of the embodiments of the Figures 7 and 9 it will be advantageous to provide the subset with Figures 10 to 13 a longitudinal central partition vertically connecting the two half-shells.

Naturally, the present description is given only as an indication, and one could adopt other implementations thereof without departing from the scope of the present invention. For example, the inner shell could be doubled and thus a stack comprising alternately layers of fibers and layers of foam for the subassembly. It could still have several longitudinal partitions, transverse or other appropriate directions, these partitions forming links between the bridge and the hull of the float. Optionally, these partitions can create a partitioning of the inner shell into several sealed compartments.

In addition, the invention could be applied for the construction of floats other than surf floats, for example for windsurfing floats, floats for swimming in the waves and overall, any nautical practice in which the float Mostly works in the preview mode.

Claims (10)

1. Method of making an aquatic gliding board, characterized in that it comprises the steps consisting of:

   - forming an upper half-shell (22) by thermoforming a plate (26) of extruded polystyrene foam, which is covered, on its lower surface (30), with an inner layer of resin-impregnated fibers, the upper half-shell (22) being thermoformed to form side edges (36) that are bent downward, the extruded polystyrene extending over the entire height of the lateral edges (36) ;

   - forming a lower half-shell (24) comprising a layer of foam covered, on its upper surface (32), with an inner layer of resin-impregnated fibers;

   - assembling the two half-shells so that said inner layers of resin-impregnated fibers form a hollow shell covered with a foam envelope.
2. Method according to claim 1, characterized in that, in the step of manufacturing the upper half-shell (22), the foam plate is initially thermoformed, and then covered, on a lower surface (30), with at least one resin-impregnated layer of fibers.
3. Method according to one of claims 1 or 2, characterized in that it comprises the additional step consisting of laminating at least part of the outer surface of one of the half-shells (22, 24) prior to the assembly of the two half-shells.
4. Method according to one of claims 1 to 3, characterized in that the layer of foam of at least one of the half-shells (22, 24) is constituted of extruded polystyrene.
5. Method according to any of the preceding claims, characterized in that the lower half-shell (24) does not comprise side edges.
6. Method according to any of the preceding claims, characterized in that it comprises a step consisting of providing at least one foam partition connecting the two half-shells vertically.
7. Method according to any of the preceding claims, characterized in that it comprises the additional step consisting of covering the assembled half-shells with an outer layer of fibers impregnated with thermo-hardening resin.
8. Aquatic gliding board, characterized in that it comprises an upper half-shell (22) incorporating a thermoformed plate of extruded polystyrene covered, on its lower surface (30), with an inner layer of resin-impregnated fibers, a lower half-shell (24) incorporating a layer of foam covered, on its upper surface, with an inner layer of resin-impregnated fibers, an outer layer of resin-impregnated fibers, and at least one foam partition connecting the two half-shells vertically, and in that the upper half-shell (22) is thermoformed to form side edges (36) that are bent downwards, the thermoformed extruded polystyrene extending over the entire height of the side edges (36).
9. Aquatic gliding board according to claim 8, characterized in that the layer of foam of the lower half-shell is constituted of extruded polystyrene.
10. Aquatic gliding board according to one of claims 8 or 9, characterized in that it comprises a plurality of partitions oriented in the longitudinal, transverse, or other directions.

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