EP3415206B1 - Glideboard - Google Patents

Description

Technical area

The invention relates to the field of sliding sports using a board, and in particular sliding sports on snow. It relates more specifically to an internal structure of a board, and in particular of a ski or snowboard. It relates more particularly to a structure of the internal core of such a board, intended to improve both the performance and the comfort of the user.

Prior techniques

In general, a board for gliding on snow has a structure comprising a lower assembly and an upper assembly, each including reinforcement layers, which are separated by an internal core making it possible to separate these rigid reinforcement layers relative to the fiber. neutral. Such a sandwich-type structure thus has flexural and torsional rigidity which allows the board to move on the snow while ensuring both the contact of the gliding sole on the snow, and the grip of the side edges when the board is tilted.

In practice, the reinforcing layers are made of materials exhibiting high rigidity, based on metal, or on a fibrous material impregnated with resin in the form of a composite material. The core is for its part made of a material which must have multiple qualities which are mainly a mass as low as possible, and a certain resistance to crushing.

Among the materials giving satisfaction for this core, we can note light woods, such as poplar or balsa, or even corrugated cardboard, with regard to the boards whose core is manufactured before the molding of the whole of the structure. For skis whose core is made during molding, by injecting an expandable material into the space formed between the upper assembly and the lower assembly, the polyurethane foam is frequently used. It has already been proposed to produce complex cores, combining different types of materials.

Thus, the document EP 2 384 964 describes a gliding board in the form of a snowboard, the core of which has in the central part an element of greater rigidity. This element is intended to serve as a side edge when the board is cut in two along a longitudinal plane, in order to ensure the seal vis-à-vis the rest of the core. Moreover, the document US 2011/206895 describes a gliding board, the structure of which comprises metallic elements arranged vertically in lateral zones, and in contact with longitudinal beams of the core, with the aim of stiffening this structure.

We have also described in the document FR 2 655 864 , a gliding board combining different zones arranged parallel in the longitudinal direction. These different zones are arranged in such a way that they can move relative to one another during the molding of the board, so as to absorb the deformations induced by the presence of localized reinforcing elements, or so as to produce nuclei which present rugged shapes.

The document AT 388 875 describes a gliding board whose structure incorporates an elastomeric layer which covers part of the beams forming the core, and has a fraction interposed between the core and the upper or lower assembly.

Disclosure of the invention

One of the objectives of the invention is to provide a gliding board which has both good grip properties, in particular by improving these properties in transverse bending, with nevertheless comfortable behavior.

• un ensemble inférieur formé d'une semelle de glisse bordée de carres, et d'une ou plusieurs couches de renfort inférieur ;
• un ensemble supérieur formé d'une ou plusieurs couches de renfort supérieur, et d'une couche supérieure de protection et de décoration ;
• un noyau interposé entre les ensembles inférieur et supérieur ;
• un élément longiligne s'étendant dans la direction longitudinale de la planche, séparant le noyau en deux parties, et venant au contact des ensembles supérieur et inférieur.

To do this, the Applicant has designed a board for gliding on snow, which has a structure including:

• a lower assembly formed of a gliding sole bordered by edges, and one or more layers of lower reinforcement;
• an upper assembly formed of one or more upper reinforcement layers, and an upper protective and decorative layer;
• a core interposed between the lower and upper sets;
• an elongate element extending in the longitudinal direction of the board, separating the core into two parts, and coming into contact with the upper and lower assemblies.

According to the invention, this gliding board is characterized in that the elongated element is formed by the assembly of at least three layers extending vertically at least over the entire height of the core. These three layers comprise a central layer made of a material having a transverse Young's modulus greater than the transverse Young's modulus of the material making up the core, and two lateral layers coming into contact with the central layer, and made of an elastomeric material.

The invention consists in segmenting the core so as to increase its bending stiffness, its transverse bending stiffness, and its torsional stiffness with respect to a monolithic core without an elongate element, while increasing the crushing resistance of the core since the central layer of the elongated element comes into contact vertically with the upper and lower assemblies, while being separated horizontally from the beams of the core by the elastomeric layers. These differences in stiffness are however felt to a lesser extent on the board since the lower and upper reinforcements strongly stiffen the core.

In particular, the improvement of the mechanical properties, in particular in transverse bending, thanks to the specific structure of the core, makes it possible to favor the use of fibrous reinforcements which have limited transverse mechanical properties, but which are easier to conform than metal reinforcements.

Moreover, the fact of separating the two parts of the core by this elongated element appreciably modifies the dynamic behavior of the board. Indeed, the assembly obtained by the two parts of the core and the elongated element behaves like an assembly formed of a main mass with which is associated a dynamic mixer. Thus, when the board tilts on the edge, the part of the core located close to the edge in contact with the snow constitutes the main mass and the assembly formed by the other part of the core constitutes the mass of the beater while the element elongated constitutes the stiffness and / or the damping of the beater. This makes it possible to obtain a shift in the resonant frequencies of the board, or even also a reduction in the amplitude level at the resonant frequencies, this making it possible to obtain a board vibrating less on the edge, more anchored on its trajectory, the user thus appreciating the comfort obtained due to the reduction in vibrations. The elongated element being formed of three layers of elastomer-reinforcement-elastomer type, this makes it possible to choose the stiffness of the beater, more precisely by the choice of the central reinforcing layer and the damping of the beater by the choice of the elastomeric side layers . In addition, the presence of the central reinforcement makes it possible to avoid significant transverse deformation and a break between the two parts of the core, and makes it possible to create shear inside the elastomeric layers to dissipate the energy and dampen the level of vibrations. .

The invention can be implemented on different types of cores, and in particular cores made of wood, or of injected foam, typically based on polyurethane.

In practice, the elongate element extends over part of the length of the board, or even over the entire length of the core. In the first case, it can be located at different levels of the board, either at the front or at the rear, with preferably a presence at the level where the forces on the edges are exerted during the turning phases, namely at the level of the zone where the binding is located.

In the first case, the characteristic elongate element is associated with the other parts of the core before molding, or even during molding. In the case of an injected ski, the characteristic element can be placed inside the mold, and delimits two volumes into which the foam of the core will be injected during the molding operation.

In practice, the elongated element may have a central layer made of a material chosen from the group comprising aluminum, acrylonitrile butadiene styrene (ABS), or even composite materials based on long or short fibers.

In practice, good results are observed in terms of grip of the board in bends when the material of the central layer has a transverse Young's modulus greater than three times the Young's modulus of the core material, preferably greater than ten. times.

In practice, the central layer of the elongated element may have a width of between 0.3 and 4 mm, preferably between 0.6 and 2 mm.

It is possible to adjust the desired mechanical properties by varying both the width of the central layer of the elongate element, and the material employed. Thus, good results have been obtained when the combination of these parameters means that the product between the width of the central layer and the Young's modulus of the material which constitutes it is greater than 10,000 mm.MPa, and preferably more than 30,000 mm .MPa.

In practice, the side layers of the elongated element can be made of a material chosen from the group comprising rubber, thermoplastic polyurethanes, styrene-ethylene-butadiene-styrenes (SEBS), or even other materials with properties elastomeric.

In practice, the material of the side layers can advantageously be a viscoelastic material, which has a sufficient damping coefficient, and optimized for operation over a temperature range ranging from -20 ° C to + 5 ° C, which allows '' ensure efficient dissipation of the mechanical energy generated in the structure during the deformation of the board.

In practice, these side layers can advantageously have a width of between 0.1 and 1 mm, preferably between 0.3 and 0.7 mm.

In particular, in the case where the board is intended for alpine skiing, for example a first type of comfortable ski is obtained by using an elongate element composed of a central layer of 2mm thick ABS covered on each of them. its two lateral sides with a rubber layer 0.5mm thick. A second type of ski that is comfortable and more efficient can be obtained by using an elongated element composed of a layer of central aluminum 0.6mm thick covered on each of its two lateral sides with a layer of rubber 0.5mm thick. thickness.

The principle of the invention can be broken down by including several similar elongate elements arranged in parallel, either spaced from each other so as to form a larger number of portions of the core to create several dynamic beaters, or contiguous to each other to modify the parameters of the dynamic beater and in particular its parameters of mass, stiffness and / or damping.

Brief description of figures

• la figure 1 est une vue en coupe transversale d'une planche de glisse conforme à l'invention,
• la figure 2 est une vue de détail de la zone II de la figure 1.
• la figure 3 est une vue de dessus du noyau de la planche de la figure 1.

The manner of carrying out the invention, as well as the advantages which result therefrom, will emerge clearly from the description of the embodiment which follows, in support of the appended figures in which:

• the figure 1 is a cross-sectional view of a gliding board according to the invention,
• the figure 2 is a detail view of zone II of the figure 1 .
• the figure 3 is a top view of the core of the plank of the figure 1 .

Of course, the dimensions and proportions of certain constituent elements of the invention may have been deformed, exaggerated and deviated from reality, with the aim of making the invention clearly understood.

Manner of carrying out the invention

As shown in figure 1 , the gliding board 1 comprises a lower assembly 2, and an upper assembly 3, separated by a core 4. More precisely, the lower assembly 2 comprises a gliding sole 7, typically based on polyethylene, on which the laterally rest the fins of the metal edges 8. In the form illustrated, this lower assembly 2 also includes a reinforcing layer 9. This layer can be made from different materials and in particular based on metal, or preferably for reasons of overall weight, by composite materials, including high tenacity fibers, such as glass, aramid, basalt or the like, mainly oriented parallel to the longitudinal axis of the board. It is of course possible for the lower assembly 2 to include several reinforcing layers, of a similar or different nature and dimension, without departing from the scope of the invention.

The board 1 also includes an upper assembly, which comprises starting from the top a decorative and protective layer 11 , resting on a reinforcing layer 12. The decorative and protective layer 11 can be made in different ways, and include on its lower face of the visible printed areas from the upper face of the sheet, or even areas transparent, making it possible to make the reinforcing layer 12 visible from the outside. Multiple variant embodiments can be envisaged as regards this decorative and protective layer, without departing from the scope of the invention.

In the form illustrated, the upper assembly 3 comprises a reinforcing layer 12, which can also be made in different ways, and in particular in metal or preferably in composite material. This reinforcing layer 12 can adopt different geometries depending on the overall geometry of the board, and in particular on the possibly three-dimensional shape of the upper face of the board. This layer can also be multiple, by combining different thicknesses of identical, similar or different nature.

The upper 3 and lower 2 sets are separated mainly by the core 4, which is bordered laterally by the edges 5 which protect the core from external humidity, and which ensure the transmission of forces from the upper assembly to the edges 8 .

According to one aspect of the invention, this core 4 has a particular structure, since it includes an elongated element 20, which separates the core 4 into two lateral parts, left 21, and right 22. This elongated element extends as illustrated in the figure 3 along the entire length of the nucleus, along its median longitudinal plane. However, in other variants not shown, this elongated element may be shorter, and extend only over only part of the length of the core.

As shown in figure 2 , this elongated element 20 extends vertically between the upper 3 and lower 2 assemblies and has a height identical to that of the core. In other variants, the elongated element may be higher than the core and be inserted between two parts of an upper (or lower) reinforcement, penetrating into the upper (or lower as the case may be) assembly. In variant not shown, the upper or lower assembly can each include a localized layer, intended to form the interface between the elongated element and the rest of the upper or lower assembly.

This elongated element 20 is composed of several layers assembled vertically, and interposed between the two parts 21, 22 of the core. The central layer 30 of the elongated element is made of a material which is clearly more rigid than the rest of the core, and more precisely which has a Young's modulus in the transverse direction which is clearly higher than that of the material constituting the rest of the core.

Different materials can be used to produce this central layer 30, and in particular metallic materials and in particular based on aluminum such as aluminum alloy 7075, also known under the name “Zicral”. Good results have been obtained with a thickness e ₁ of this central layer 30 close to 0.6 mm. The transverse Young's modulus of this material is close to 70,000 MPa, to be compared with the transverse Young's modulus of the woods used for the manufacture of cores, is generally between 500 and 1000 MPa. It will be noted in particular that taking into account the essentially longitudinal orientation of the fibers of the wood used for the manufacture of the cores, the Young's modulus in the longitudinal direction of these materials is generally higher, between 5,000 and 15,000 MPa.

In an alternative embodiment, a polymeric material, and in particular ABS, with a thickness e ₁ of the order of 2 mm can be used to form the central layer 30 of the elongated element 20 , this material having a Young's modulus of the order of 1800 MPa.

According to the invention, this central layer 30 is bordered by two side layers 31, 32 which are made of an elastomeric material. Good results were obtained using rubber, with a thickness e ₂ of the order of 0.5 mm.

The various layers of the elongated element are assembled together and with the rest of the core by gluing, for example.

Thanks to the presence of the characteristic elongate element, an increase in the flexural stiffness of the core has been observed. It being understood that most of the flexural rigidity of the board is conferred by the presence of the reinforcing layers of the upper and lower assemblies, the impact of this increase in flexural stiffness of the core on that of the board is however marginal. At the same time, there is an increase in the stiffness in transverse bending and in torsion of the core. Indeed, in particular in the case where the reinforcing layers of the upper and lower assemblies are based on unidirectional fibrous materials, oriented longitudinally, the transverse bending stiffness conferred by these reinforcements is relatively limited compared to that measured in the longitudinal direction. . The contribution of the rigidity of the characteristic elongated element is particularly important for the dynamic behavior of the board. An increase in torsional stiffness was also observed due to the presence of the characteristic elongate element.

Additionally, the use of an elastomeric material, and advantageously viscoelastic, makes it possible to generate vertical shear phenomena during the flexural deformation of the board, with energy dissipation making it possible to generate a certain damping.

Overall, the behavior of a board according to the invention, and in particular its dynamic behavior on snow, makes it possible to obtain a board with improved grip, when the board is on the edge and a sharper registration in the curves. due to the attenuation of vibrations, the board remains more easily inscribed on its trajectory. At the same time the effect damping generated by the association of a rigid material and an elastomeric material within the elongated element gives the board a certain softness in the deformation, and therefore a more comfortable board for the user.

Of course, even if the invention has been described in the examples for a “sandwich” type structure, it can also be applied for so-called “shell” overall structures, in which the upper assembly extends laterally vertically up to 'to join the lower unit directly above the edges, including the core without requiring side edges.

Claims (10)

1. A ski (1) having a structure including :

   • a lower assembly (2) formed by a base (7) bordered by edges (8) and one or more lower reinforcing layers (9) ;

   • an upper assembly (3) formed by one or more upper reinforcing layers (12) and an upper protective and decorative layer (11) ;

   • a core (4) interposed between the lower assembly (9) and the upper assembly (3);

   • an elongated element (20) extending in the longitudinal direction of the ski, separating the core into two portions (21, 22) and coming into contact with the upper assembly (3) and lower assembly (2),

   characterized in that the elongated element (20) is formed by assembling at least three layers extending vertically between the upper assembly (3) and lower assembly (2), the three layers comprising a central layer (30) produced from a material having a transverse Young's modulus which is higher than the transverse Young's modulus of the material composing the core (21, 22), and two lateral layers (31, 32) which come into contact with the central layer (30) and are produced from an elastomeric material.
2. The ski as claimed in claim 1, characterized in that the core (21, 22) is produced from wood.
3. The ski as claimed in claim 1, characterized in that the core (21, 22) is produced from injected foam, typically based on polyurethane.
4. The ski as claimed in claim 1, characterized in that the central layer (30) is produced from a material selected from the group comprising aluminium, acrylonitrile butadiene styrene, and fibre-based composite materials.
5. The ski as claimed in claim 1, characterized in that the material of the central layer (30) has a transverse Young's modulus which is more than ten times the Young's modulus of the core material.
6. The ski as claimed in claim 1, characterized in that the central layer (30) has a width in the range 0.3 to 4 mm.
7. The ski as claimed in claim 1, characterized in that the product of the width of the central layer and the Young's modulus of the material which constitutes it is more than 10000 mm.Mpa.
8. The ski as claimed in claim 1, characterized in that the lateral layers (31, 32) are produced from a material selected from the group comprising rubber, thermoplastic polyurethanes, and styrene-ethylene-butadiene-styrenes.
9. The ski as claimed in claim 1, characterized in that the lateral layers have a width in the range 0.1 to 1 mm, preferably in the range 0.3 to 0.7 mm.
10. The ski as claimed in claim 1, characterized in that it comprises a plurality of similar elongated elements which are disposed parallel to each other in the transverse direction.

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