EP3730197A1 - Reinforcement for gliding board - Google Patents

Abstract

Gliding board (1) comprising at least one upper reinforcement (5), one lower reinforcement (7), an intermediate structure placed between said upper reinforcement and said lower reinforcement, characterized in that at least one of the upper reinforcements or lower reinforcement consists of an assembly of carbon fibers and basalt fibers, said basalt fibers representing a proportion of between 15% and 70% of the total weight of said lower or upper reinforcement, preferably between 45% and 55%.

Description

The invention relates to a gliding board for the practice of winter sports. In particular, the invention relates to a gliding board comprising a composite structure. The invention is particularly suitable for the manufacture of skis but can also be used for the manufacture of snowboard snowboards or any other sliding device.

It is known in the field of snow sliding sports to construct sliding boards using a composite structure. A typical composite structure for a gliding board has an upper sub-assembly, a lower sub-assembly, and an intermediate core. Functionally, the lower sub-assembly is among other things responsible for the functions of gliding and grip on snow, while the upper sub-assembly constitutes the top of the ski. It is also known to equip each of the upper and lower subassemblies with reinforcing elements. These upper and lower reinforcement elements are very important mechanical components of the gliding board, because the mechanical characteristics of the gliding board are mainly influenced by the mechanical characteristics of the reinforcements. The core has, for its part, mainly an intermediate function, it maintains the distance between the lower reinforcement and the upper reinforcement. The assembly formed by the upper and lower reinforcement elements constitutes a deformable beam. The skiability, the behavior of the board for gliding on snow is, of course, dependent on the weight of the latter but above all on its behavior in bending and, to a lesser extent, in torsion. This is why the designer of sliding boards will take particular care in the realization of the reinforcement elements. Both the upper reinforcement and the upper reinforcement can comprise one or more distinct or identical layers. The reinforcing layers generally consist of a fibrous structure embedded in a matrix of thermoplastic or thermosetting resin which represents approximately 40% of the total weight of the reinforcement. Often the fibers used are glass, carbon or other fibers. Each of these fibers has its own characteristics and their use for the manufacture of a gliding board leads to different behaviors in terms of skiability.

Until now, fiberglass has been used very often, especially because of its good quality / price ratio. However, it has the drawback of being heavy and not very dynamic. In addition, a reinforcement made of fiberglass has a thickness of between 0.3 and 1 mm.

To remedy the drawbacks of fiberglass, it is known to use carbon fibers. The latter are lighter than glass fibers and above all, they have a much higher Young's modulus. In certain configurations of constructions, the reinforcements made of carbon fibers give the ski a vibrating side which has the consequence of damaging the precision of piloting. In fact, vibrations cause loss of contact between the edges of the ski and the snow.

It is also known practice to design reinforcements which combine fibers of different types, for example in document FR 3017306 which describes the manufacture of a reinforcement combining natural flax fibers with carbon fibers. This solution is not completely satisfactory because it turns out to be a little heavy and offers characteristics which are closer to those of fiberglass rather than to those of carbon fiber.

The present invention aims to remedy the aforementioned drawbacks. In particular, the present invention aims to provide a reinforcement which can be used for the manufacture of a gliding board which improves its damping properties.

The objective of the invention is achieved by providing a gliding board comprising at least one upper reinforcement, one lower reinforcement, an intermediate structure placed between said upper reinforcement and said lower reinforcement, characterized in that at least one upper reinforcement or lower reinforcement consists of an assembly of carbon fibers and basalt fibers, said basalt fibers representing a proportion of between 15% and 70% of the total weight of said lower or upper reinforcement, preferably between 45 % and 55%.

In a first embodiment, the reinforcement comprises a plurality of strands of carbon fiber and a plurality of strands of basalt fiber, said strands of carbon fibers and said strands of basalt fiber being arranged on the same layer so as to that the strands of basalt fibers are interposed between strands of carbon fibers.

In a second embodiment, the reinforcement comprises an assembly of a plurality of juxtaposed panels and in that part of the panels are made from plies of basalt strands arranged unidirectionally while another part of the panels are made. from a web of carbon strands also arranged unidirectionally.

In a third embodiment, the reinforcement comprises a fiberglass ply, a carbon ply and a ply comprising basalt fibers.

• [Fig. 1] La figure 1 est une coupe transversale d'un ski équipé de renfort selon l'invention.
• [Fig. 2] La figure 2 est une vue en coupe d'un renfort selon un premier mode de réalisation de l'invention.
• [Fig. 3] La figure 3 est une vue en coupe d'un renfort selon un premier mode de réalisation de l'invention.
• [Fig. 4] La figure 4 est une vue en coupe d'un renfort selon un troisième mode de réalisation de l'invention.
• [Fig. 5] La figure 5 est un graphe comparant l'évolution des capacités d'amortissement d'un renfort selon l'invention avec la même évolution pour des renforts de l'art antérieur.

The invention will be better understood in the light of the following description in which:

• [ Fig. 1 ] The figure 1 is a cross section of a ski equipped with reinforcement according to the invention.
• [ Fig. 2 ] The figure 2 is a sectional view of a reinforcement according to a first embodiment of the invention.
• [ Fig. 3 ] The figure 3 is a sectional view of a reinforcement according to a first embodiment of the invention.
• [ Fig. 4 ] The figure 4 is a sectional view of a reinforcement according to a third embodiment of the invention.
• [ Fig. 5 ] The figure 5 is a graph comparing the evolution of the damping capacities of a reinforcement according to the invention with the same evolution for reinforcements of the prior art.

The figure 1 shows in cross section a ski according to the invention. In known manner, this comprises an upper sub-assembly, a lower sub-assembly and an intermediate structure placed between the two sub-assemblies. Each of the sub-assemblies includes a reinforcement. In a ski or more generally in a gliding board according to the invention, at least one of the reinforcements is designed according to the invention.

The upper sub-assembly comprises an upper reinforcement 5 and a top layer 6. The lower sub-assembly comprises at least one lower reinforcement 7, a gliding sole 8 and metal edges 9.

The intermediate structure comprises a core 10 made of wood or synthetic material and side edges 11.

The figure 2 shows in cross section a reinforcement 4 according to a first embodiment of the invention.

The carbon fibers each having a thickness of between 5 μm and 10 μm are first assembled with each other to form strands 12 of substantially cylindrical shape. Each strand 12 is of the type between 3K and 48K, that is to say it comprises between 3000 and 48000 carbon fibers. In the embodiment presented here, each carbon strand is of type 12 K, that is to say comprising approximately 12,000 fibers.

Similarly, the basalt fibers, the thickness of which is between 5 and 15 μm, are first assembled together to form strands 13. Each strand has a count of between 68 Tex and 2400 Tex. They may be natural fibers or modified fibers of the Filava type (registered trademark). In the embodiments described here, strands of about 1200 Tex were used.

The strands and strands are draped over a single layer. The carbon strands 12 and the basalt strands 13 are interposed with each other. In this configuration, it is preferable that the carbon strands and the basalt strands have substantially the same diameter. So to vary the weight distribution of the basalt and carbon fibers, it suffices to modify the diagram according to which the strands are inserted between them: 1-1, 2-1, 3-1, etc ......

The entire layup of the carbon and basalt strands can be held in place using a light veil or a grid and a stitching thread which places the draping on the veil in places.

It is also possible to make the prepreg at the same time as the impregnation. In this case we can do without veil and thread.

When the reinforcement is not pre-impregnated, it is at the time of molding, for the manufacture of the ski, that the reinforcement will be brushed with uncrosslinked resin. After curing, the lay-up of the carbon strands and the basalt strands embedded in the crosslinked resin constitutes the upper or lower reinforcement of the ski 1.

The variation in the count and the relative thickness of the diameter of the basalt and carbon strands respectively makes it possible to vary the weight distribution of the two materials of the reinforcement. In practice, the basalt fibers can represent a percentage of between 15% and 70% of the weight of all the fibers of the reinforcement. However, better results were observed for a percentage between 45% and 55%.

The figure 3 represents a reinforcement 4 "according to a second embodiment of the invention. The reinforcement 4" consists of an assembly of a plurality of juxtaposed and superimposed panels. The panels 17 are made from layers of basalt strands arranged unidirectionally. The panels 18 are made from a sheet of carbon strands also arranged unidirectionally. The panels 17 and 18 are juxtaposed so as to constitute a first layer. The panels 17, 18 have a thickness between 0.1 and 0.5 mm so that it is possible to superpose several layers thus formed to constitute a lower or upper reinforcement which has the usual thickness of a reinforcement by example made exclusively in fiberglass. It is, on the other hand, possible to produce an upper or lower reinforcement whose composition does not have a homogeneous structure over its entire length with a greater proportion of carbon at the level of the ski skate than it is. at the front and rear portions of the ski. The orientation of the fibers in the different panels 17 and 18 may be parallel or else form a non-zero angle with each other.

The figure 4 represents a reinforcement 4 '"according to a third embodiment of the invention. It is an upper or lower reinforcement. It is a reinforcement which combines three plies of different material: a fiberglass ply 21, a carbon ply 22 and a ply comprising basalt fibers 23. The carbon ply 22 may for example be produced in the form of a ply of carbon strands arranged unidirectionally. The basalt ply 23 is for its part a juxtaposition of basalt strands and carbon strands in a proportion between 15% and 70%.

In order to fully understand the benefit of the reinforcements according to the invention, the applicant has produced test pieces on which several experiments have been carried out. Indeed, taking into account the manufacturing process of a ski, it is only when the ski is finished, with all its components, that the reinforcement has the desired mechanical characteristics.

Initially, five test pieces were carried out. These five test pieces are made to have a bending constant identical to a fiberglass reinforcement of 1000g / m ² . This corresponds to the basis weight of an upper or lower reinforcement usually used in a ski. Since fiberglass reinforcements are the most widely used in the manufacture of skis, the mechanical characteristics of these specimens are compared with those of the fiberglass specimen.

The results are compiled in Table 1 (See Table 1 below). It is clear that the weight and thickness of a reinforcement combining carbon fibers and basalt fibers are halved compared to the glass reinforcement having a similar bending constant. [Table 1] Material % weight Mpa module Fiber weight for 1000g / m ² glass fiber equivalent Reinforcement weight for equivalent 1000g / m ² fiberglass Thickness for equivalent 1mm glass reinforcement Glass 100% 37,000 1000 1538 1.00 Basalt 100% 45,000 862 1326 0.82 Carbon 100% 97,000 303 504 0.36 CFX1 Carbon 40% 43,000 645 1112 1.12 Linen 60% CBX Carbon 50% 70,000 513 828 0.53 Basalt 50%

Secondly, the test pieces are compared in a damping experiment. In this experiment, we measure the tangents δ (delta), that is to say the phase shift between the wave to which the test piece is subjected and its own vibration, this as a function of the frequency of the wave at which she is submissive.

It is then clearly seen that, whatever the frequency, between 0 Hz and 50 Hz, the damping performance of the specimen containing 50% of basalt fiber and 50% of carbon fiber by weight, is between 30% and 50% better than that of specimens containing only carbon.

These experiments and comparisons highlight the advantage of using a certain proportion of basalt fiber inside a carbon reinforcement. The advantages provided by the placement of one or two reinforcements according to the invention in a ski can also be perfectly assessed when comparing skis according to the invention with skis having simple fiberglass reinforcements or else carbon fiber reinforcements. The main advantages are in particular a controlled weight and better damping of vibrations.

The invention has mainly been described for the manufacture of a pair of skis for the practice of alpine skiing. It nevertheless applies to any gliding board, for example for a snowboard.

Claims (4)

Gliding board (1) comprising at least one upper reinforcement (5), one lower reinforcement (7), an intermediate structure placed between said upper reinforcement and said lower reinforcement, characterized in that at least one of the upper reinforcements or lower reinforcement consists of an assembly of carbon fibers and basalt fibers, said basalt fibers representing a proportion of between 15% and 70% of the total weight of said lower or upper reinforcement, and in that said reinforcement comprises a plurality of strands of carbon fiber and a plurality of strands of basalt fiber and in that the strands of carbon fibers and the strands of basalt fiber are arranged on a same layer so that the strands of basalt fibers are interposed between strands of carbon fibers. Gliding board (1) according to Claim 1, characterized in that the proportion of basalt fibers is between 45% and 55%. Gliding board (1) according to one of the preceding claims, characterized in that said reinforcement comprises an assembly of a plurality of panels (17, 18) juxtaposed and / or superimposed and in that part of the panels (17 ) are made from layers of basalt strands arranged unidirectionally while another part of the panels (18) are made from a layer of carbon strands also arranged unidirectionally. Gliding board (1) according to one of the preceding claims, characterized in that said reinforcement comprises a fiberglass ply (21), a carbon ply (22) and a ply comprising basalt fibers (23).

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