CORE FOR SLIDING BOARD AND CORRESPONDING SLIDING BOARD

Description

Domaine technique :

[0001] The invention relates to the field of sliding boards, in particular snow sliding boards.

[0002] It specifically targets a new core structure comprising plywood elements, enabling the board to have good mechanical properties, particularly in terms of resistance to compression, torsion and bending. Techniques antérieures :

[0003] Generally speaking, a ski board has a core extending over almost the entire length of the board, and whose role is essentially to give thickness to the ski, by separating mechanical reinforcements and keeping them away from the neutral fiber.

[0004] The cores can be formed by injecting components that react together to form a foam into the board mold or into a specific mold designed to obtain the core. Another technique involves cutting and machining the core prior to molding. The invention relates more specifically to this family of cores.

[0005] These cores can therefore be made of various materials, such as polymer foam or, more frequently, wood.

[0006] These cores are therefore made during a pre-molding operation, and they are cut and machined so that their external contours correspond to the desired volume, in order to sufficiently separate the fibrous reinforcements that come into contact with it.

[0007] Generally, the wood-based cores of the prior art are formed from a series of wood strips oriented along a longitudinal axis of the board and glued together. The resulting panel is called a laminated / glued panel.

[0008] As an example, document FR843973 describes a ski consisting of a wooden core made of wood strips oriented along the longitudinal axis of the board and glued together. These wood strips are made from solid wood with wood fibers oriented along the thickness axis of the board. The board also has a thinner bottom and top layer with longitudinally oriented wood fibers; these layers act as reinforcements, a base, and a top layer.

[0009] Such a core provides the board with good compression resistance. However, the board is not suitable for withstanding significant torsion or bending.

[0010] There are also cores formed from thin layers of wood superimposed and bonded together during molding.

[0011] Thus, document DE 295 02 290 describes a snowboard incorporating a core made up of a superposition of layers of wood whose wood fibers are oriented, in turn, along the longitudinal axis of the snowboard, along the transverse axis, at 90°, and along the diagonals, i.e. at plus or minus 45°.

[0012] This type of stacking ensures consistent board performance on snow or water, as the wood fibers have several preferred orientations, distributed at specific angles. Furthermore, manufacturing such a snowboard requires particularly meticulous and delicate handling, which increases the production cost.

[0013] However, such a core does not provide the board with good compression resistance, nor does it improve the board's mechanical properties, particularly in bending and torsion.

[0014] Other examples are disclosed in documents FR2909893 and WO9108029.

[0015] The technical problem that the invention aims to solve is therefore to develop a core that gives a board good mechanical properties in compression, bending and torsion. Description de l'invention

[0016] To solve this problem, the invention proposes to develop a core for a sliding board, comprising an upper face and a lower face intended to come into contact with the sliding base, the lower face defining a plane comprising a longitudinal axis oriented along the length of the board and a transverse axis, oriented along the width of the board, the core having a thickness measured along a direction perpendicular to said lower face of the core.

[0017] Such a core comprises: at least one plywood element of a first type comprising alternating layers with wood fibers oriented along the longitudinal axis and layers with wood fibers oriented along the transverse axis, and at least one plywood element of a second type comprising alternating layers with wood fibers oriented along the longitudinal axis and layers with fibers oriented along the thickness of the core.

[0018] In other words, the first type element, which has an alternation of wood fibers oriented along the transverse axis and along the longitudinal axis of the core, provides resistance to torsion and bending.

[0019] The second type of element, which includes alternating wood fibers oriented along the thickness and along the longitudinal axis of the core, provides resistance to compression and bending.

[0020] Thus, the combination of these two elements within the core provides good strength in all three spatial directions: thickness, length, and width. The core's mechanical strength is therefore improved in compression, bending, and torsion.

[0021] Furthermore, the choice of the arrangement of the elements, in relation to each other, makes it possible to prioritize areas of the core that require particular reinforcement.

[0022] For example, the center of the boot (CM), which designates a reference point on the ski indicating to the boot fitter where to position the binding so that the ski boot is roughly centered around this reference point, can be reinforced. This area of ​​the ski is subjected to the most compressive stress, as it is the skier's point of contact. Therefore, it is advisable to prioritize a large proportion of the second type of reinforcement in this area.

[0023] Conversely, the front contact point (PA), which designates the point of contact between the ski and the ground, can be reinforced against bending. Indeed, this area of ​​the ski is subjected to the most bending and torsional stresses, for example, to follow the geometry of the ski slope. It is therefore advisable to prioritize a large proportion of the first type of element in this area.

[0024] Furthermore, plywood is a robust, easy-to-work-with material that does not warp under the effects of heat or humidity. Since skis, snowboards, and surfboards are subjected to humid environments such as snow or seawater, the properties mentioned above make plywood an ideal material for constructing boards.

[0025] Plywood is also preferred because it fits in with the current trend towards a return to more durable, environmentally friendly, and easily recyclable materials.

[0026] In practice, the layers forming the plywood components are between 1 and 3 mm thick. The thinness of each layer allows for greater flexibility and better cohesion between the different layers. Choosing the thickness of each plywood layer allows for adjusting the rigidity in bending / compression or bending / torsion of the plywood components used to form the core.

[0027] According to another characteristic, the elements of the first and second type each have an odd number of layers.

[0028] An odd number of layers ensures that the same type of layer is found on the outer surfaces of the element. The plywood element thus has a plane of symmetry at its center, with the layers distributed symmetrically around this plane. Consequently, the mechanical properties of the plywood element are also symmetrical about this plane, which reduces the risk of damaging the core. Indeed, unevenly distributed stresses on the core can create irreversible cracks or deformations, degrading the board's performance or even rendering it unusable.

[0029] The elements of the first and second type can be positioned in the ski mold directly on top of each other or next to each other without any special interface element.

[0030] In practice, in order to facilitate their assembly or mechanical connection with each other, the elements of the first and second type can advantageously be separated by an intermediate layer of adhesive.

[0031] Alternatively, the elements of the first and second type are preferably separated by an intermediate reinforcing layer which can be made of a material included in the group including metals and high-tenacity fibers such as glass fibers and basalt fibers.

[0032] High-tenacity fibers offer excellent tensile and compressive strength while maintaining good flexibility and lightness. Furthermore, the fiber impregnation resin can also provide bonding properties.

[0033] The addition of an intermediate layer thus allows a degree of flexibility and some freedom of movement between two elements of different types, in order to improve the transmission of forces between these two elements.

[0034] Depending on the number and arrangement of the first and second type elements, the intermediate layer may contain fibers oriented along the longitudinal axis or fibers oriented along the transverse axis. Thus, the mechanical strength properties are improved in the preferred fiber direction.

[0035] In a particular embodiment, the intermediate layer may comprise both fibers oriented along the longitudinal and transverse axes.

[0036] There are several embodiments that allow the development of kernels that address the problems stated above.

[0037] According to a first embodiment, the core comprises an element of the first type and an element of the second type, the element of the first type being at least partially covered by the element of the second type.

[0038] Such a core therefore comprises an element of the first type, covering the entire width of the core and intended to absorb the torsional and bending forces experienced by the board in order to stabilize the ride of a user, and an element of the second type, superimposed on the element of the first type, narrower and intended to resist the compressive forces exerted on the board.

[0039] In practice, at the mid-length of the core, the second type of element covers between 30 and 80%, or even 100%, of the upper surface of the first type of element. The mid-length of the core is designed to be located near the ski boot's support zone. Therefore, due to its proximity to the boot's support zone, this area requires compression reinforcement, which explains the coverage of the second type of element.

[0040] In some embodiments of this first embodiment, the element of the first type may have a constant thickness, while the element of the second type has a variable thickness to follow the thickness profile of the core.

[0041] Alternatively, the element of the second type may have a constant thickness, while the element of the first type may have a variable thickness to adapt to the thickness of the core.

[0042] According to a second embodiment, the core comprises two elements of the first type and one element of the second type, the element of the second type being arranged in the central area of ​​the core, the elements of the first type being arranged on either side of the element of the second type.

[0043] Such a core therefore comprises a central element designed to resist the compressive forces exerted on the board. The lateral elements, for their part, are designed to absorb the torsional and bending forces experienced by the board in order to stabilize the user's movement.

[0044] In a particular embodiment of this second embodiment, the element of the second type may have a height greater than that of the lateral elements of the first type.

[0045] This specific shape of the second type element adapts to the final thickness of the board and may allow for prioritizing the core's compressive strength.

[0046] In addition, according to another characteristic, at the median longitudinal level of the core, the element of the second type covers between 50 and 70% of the total width of the core.

[0047] According to the invention, the median longitudinal plane of the core corresponds to the mid-length of the core. In various embodiments, the mid-length of the core may not correspond to the mid-length of the ski. In practice, the mid-length of the core is generally located at the front of the ski's foot, that is, at the front of the ski boot's support area. Thus, preferably, due to its proximity to the boot's support area, this area is reinforced in compression, which explains the occupancy rate of the second type of element.

[0048] In some embodiments, the second type element may have a constant width along the entire length of the core, while the first type elements have a variable width to follow the profile of the dimension line. The first type element is then preferably parallelepiped-shaped, while the second type elements have a straight inner side and a curved outer side to follow the dimension line.

[0049] In the context of the invention, the core sidecut corresponds to the profile of the core's width evolution along its longitudinal axis. Preferably, the core sidecut corresponds to that of the ski.

[0050] Alternatively, the elements of the first type can have a constant width along the entire length of the core, while the element of the second type has a variable width to follow the profile of the dimension line. The element of the first type then has two curved sides, and the elements of the second type also have two curved inner sides and one curved outer side, to follow the shape of the element of the first type. The elements of the first type are then curved to conform to the curved lateral shapes of the central element of the second type.

[0051] In a third embodiment, the core further comprises a polyurethane element having at least one recess formed in the thickness of said polyurethane element, configured to allow the insertion of the elements of the first and second type into the at least one recess.

[0052] This construction method results in a hybrid core of polyurethane and wood. The combination of these two materials allows for great versatility in optimizing and selecting ski parameters.

[0053] Furthermore, in this embodiment, the sidecut profile of the ski is achieved by machining the polyurethane element, rather than the plywood element(s). This limits the areas of the core containing wood fibers whose length is shortened to follow the sidecut. Indeed, the short length of the wood fibers offers limited benefit since the wood's strength characteristics are reduced. Thus, the addition of polyurethane saves a significant amount of wood, which would otherwise provide only a limited mechanical advantage.

[0054] In practice, the polyurethane element comprises: a first recess made in the thickness of the polyurethane element so as to open at the level of its lower and upper face, the first recess being intended to accommodate the element of the first type in its lower portion and at least a part of the element of the second type in its upper portion, and two second recesses, made on either side of the length of the first recess so as to open at the level of the upper face of the polyurethane element, the two second recesses being intended to accommodate the remaining portions of the element of the second type.

[0055] The two recesses communicate at least partially through the upper face of the first recess and the lower face of the second recess.

[0056] According to another aspect, the invention relates to a sliding board comprising a core as described above. Brève description des figures

[0057] The invention will be well understood, and its advantages and various other features will become apparent, from the following description of some non-limiting embodiments, with reference to the accompanying schematic drawings, in which: There figure 1 is a perspective view of a portion of the core of the invention according to a first embodiment, The figure 2 is a perspective view of a portion of the core of the invention according to a second embodiment, The figure 3 is a perspective view of a portion of the core of the invention according to a third embodiment, The figure 4 is a cross-sectional view at the mid-shoe level of a board including a core according to the first embodiment of the figure 1 , There figure 5 is a cross-sectional view at the mid-shoe level of a board including a core according to a variant of the first embodiment of the figure 1 , There figure 6 is a cross-sectional view at the mid-shoe level of a board including a core according to the figure 3 , There figure 7 is an exploded perspective view of a board including a core according to the figure 3 , There figure 8 is a top view of the embodiment of the core illustrated in the figure 1 , and La figure 9 is a side view of the embodiment of the core illustrated in the figure 1 . Description des modes de réalisation

[0058] For clarity, we define a reference point Oxyz as well as plans xy, yx And xz defined from the vectors x, y And z non-collinear of the reference frame Oxyz.

[0059] The core 1000, 2000 as illustrated on the figures 1 et 2 It has a lower face designed to lie against the board's glide base, and an upper face, opposite the lower face. The lower face defines a plane P parallel to the xz plane described previously. The plane P It has a longitudinal axis, oriented along the z-axis, along the length of the board, and a transverse axis, oriented along the x-axis, along the width of the board. The core 1000, 2000 It therefore has a thickness measured along a direction perpendicular to said lower face, that is to say along the y-axis, and corresponding to the distance separating the lower face from the upper face of the core 1000, 2000.

[0060] As illustrated on the figures 1 et 2 the core 1000, 2000 of the invention consists of at least two elements 100, 110, 200, 210 distinct, made of plywood.

[0061] One element 100, 110, 200, 210 plywood thus comprises alternating layers 101, 102, 111, 112, 201, 202, 211, 212also called folds, held together by gluing. For example, the glue used may be urea-formaldehyde, melamine, phenolic or resorcinol glue.

[0062] The thickness of an element 100, 110, 200, 210 The thickness of plywood typically varies between 5 and 50 mm depending on the configuration, generally between 5 and 30 mm for alpine skis, touring skis, or snowboards, and between 5 and 50 mm for cross-country skis. The width varies between 30 and 150 mm for cross-country skis, alpine skis, or touring skis, and between 150 mm and 500 mm for wide skis or snowboards. The layers 101, 102, 111, 112, 201, 202, 211, 212 preferably have a thickness between 1 and 3 mm.

[0063] The layers 101, 102, 111, 112, 201, 202, 211, 212are obtained by cutting thin sheets from wooden panels. The wood used can come from any type of tree, with a preference for poplar. The layers 101, 102, 111, 112, 201, 202, 211, 212 They therefore contain wood fibers with a preferred orientation, which depends on the wood used and how the cutting is done.

[0064] According to a first embodiment illustrated on the figure 1 the core 1000 comprises two elements 100, 110 separate plywood.

[0065] The element of the first type 100 is formed by a stacking, along the axis of the core thickness 1000, diapers 101 featuring wood fibers oriented along the longitudinal axis of the core 1000 and diapers 102 featuring wood fibers oriented along the transverse axis of the core 1000.

[0066] In other words, the fibers of the diapers 101, 102successive angles have an orientation in the plane at 0°, then 90°, then again 0° with respect to the longitudinal axis of the core 1000.

[0067] In practice, the element of the first type 100 consists of between 1 and 10 layers, preferably with an odd number of layers and preferably 3 or 5 layers.

[0068] In the example of the figure 1 the element of the first type 100 It has a constant thickness of 5 mm and consists of three superimposed layers. 101, 102, 101 with a constant thickness of 1.66 mm.

[0069] Preferably, for ease of manufacture, the element of the first type 100 presents a constant thickness. However, alternatively, the thickness can vary along the longitudinal axis of the core. 1000, in order to adapt to the thickness of the core 1000. For example, in the case of alpine skis or touring skis, the thickness of the element of the first type100 can be between 3 and 15 mm, with the thinnest thickness located at the ends of the core 1000, while the greatest thickness is located near the central area of ​​the core 1000. Furthermore, as illustrated on the figure 8 the element of the first type 300 may exhibit a variable width along the longitudinal axis of the core 3000, to follow the profile of the sidecut. The width can therefore vary between 5 and 600 mm depending on the type of ski and / or the design. For example, in the case of alpine skis or touring skis, the width of the first type of ski element 300 can be between 50 and 120 mm, with the smallest width located near the central area of ​​the core 3000, while the greatest width is located at the ends of the core 3000.

[0070] The element of the second type 110is formed by a juxtaposition, along the transverse axis of the nucleus 1000, diapers 112 featuring wood fibers oriented along the axis of the core thickness 1000 and diapers 111 featuring wood fibers oriented along the longitudinal axis of the core 1000.

[0071] In practice, the element of the second type 110 has an odd number of layers. Preferably, the element of the second type 110 has between 10 and 50 layers for alpine or touring skis, between 5 and 30 layers for cross-country skis, and between 100 and 200 layers for a snowboard, which is a board much wider than a ski.

[0072] In the example of the figure 1 the element of the second type 110 It has a constant width of 60 mm and is made up of 5 layers 111, 112of a constant thickness of 12 mm. Alternatively, in a preferred embodiment corresponding to alpine skiing or touring skiing, the element of the second type 110 can have 27 layers 111, 112, formed by 3 stringers of 9 layers 111, 112 of 2.2 mm each and also features a constant width of 60mm.

[0073] Alternatively, the width of the element of the second type 110 can be between 50 and 100 mm, or even 150 mm for wide boards and can vary along the longitudinal axis to follow the profile of the sidecut.

[0074] Furthermore, the element of the second type 110 can have a height between 1 and 10 mm, advantageously variable along the longitudinal axis of the core 1000, to follow the core thickness profile 1000. For example, as illustrated on the figure 9 the smallest thickness of the element of the second type410 is located at the extremities of the nucleus 4000, while the greatest thickness of the element of the second type 410 is located near the central area of ​​the core 4000.

[0075] As illustrated on the figure 1 the element of the second type 110 at least partially covers the element of the first type 100. Typically, the element of the second type 110 covers between 30 and 100% of the upper surface of the first type element 100, due to the non-constant width of the ski, and in particular its sidecut. Alternatively, the element of the second type 110 can cover the entire upper surface of the first type of element 100, the two elements then having the same width.

[0076] The two elements 100, 110are bonded to each other by an intermediate layer of adhesive, for example made with a urea-formaldehyde, melamine, phenolic, or resorcinol adhesive, or even a bio-based adhesive. Advantageously, the two elements 100, 110 can be separated by an intermediate reinforcing layer 115, visible on the figure 4 , with a thickness between 0.1 and 1 mm. This intermediate reinforcing layer 115 is made of a metallic material or of a material included in the group of high tenacity fibers, such as glass fibers or basalt fibers.

[0077] As an example, the intermediate reinforcement layer 115 is made of glass fibers oriented along the longitudinal axis of the core 1000. Alternatively, the intermediate reinforcement layer 115 is made of basalt fibers oriented along the transverse axis of the core 1000.In other embodiments, the intermediate reinforcing layer 115 may include both fibers oriented along the longitudinal axis of the nucleus 1000 and along the transverse axis of the nucleus 1000. These fibers are preferably impregnated with a resin, in particular epoxy, to ensure bonding with the various constituent elements of the ski.

[0078] As illustrated on the figures 4 And 5 a board for sliding, such as a ski 1100, 1200 including a core 1001, 1002 of the invention includes a sole 140, at the ends of which are arranged the squares 130. A first layer of high-tenacity metallic or fibrous reinforcement 180 is arranged between the squares 130, on the sole 140. This first layer of fibrous reinforcement 180is composed, for example, of 720 g / m² of glass warp fibers, oriented longitudinally around the core, and 80 g / m² of glass weft fibers, oriented transversely around the core. This first layer of fibrous reinforcement 180 has a thickness of approximately 1 mm.

[0079] On the figure 4 a second layer of metallic reinforcement or high-tenacity fibrous reinforcement 190 covers the first layer of reinforcement 180 and the squares 130. This second layer of fibrous reinforcement 190 has a thickness of approximately 1mm.

[0080] The element of the first type 100 covers the 180, 190 reinforcement layer(s) over a width less than the sole 140, to allow for the arrangement of the songs 120, on either side of the element of the first type 100. In the forms of realization of figures 4 And 5 the songs 120are almost the same height as the element of the first type 100. Alternatively, the songs 120 may have a height less than or greater than that of the element of the first type 100, typically, the songs 120 can have the same height as the core 1001, 1002, that is, a height equal to the sum of the heights of the element of the first type 100 and of the second type 110.

[0081] In the example of the figure 4 an intermediate reinforcing layer 115 is arranged on the upper surface of the squares 130 and the lateral and upper faces of the element of the first type 100.

[0082] The element of the second type 110 is placed on the intermediate reinforcement layer 115, which covers the element of the first type 100. Advantageously, at the level of the ski's ski skate 1100, 1200, a metal plate 160,preferably made of Titanal® or Zycral®, with a thickness between 0.1 and 2 mm, is inserted onto the core 1001, 1002 to allow the ski and boot to separate.

[0083] A new layer of metallic or fibrous reinforcement 150 covers the upper and lateral walls of the core 1001, 1002. This reinforcing layer 150 is covered by a protective top 170 intended for the protection and decoration of skis 1100, 1200.

[0084] Any other type of ski structure, composed of composite and / or metallic reinforcements or even layers of wood positioned above and below the core, can be considered. Preferably, these reinforcements will have lower weights than those conventionally used in skis, due to a core that is more mechanically efficient than usual. Indeed, the core according to the invention contributes to the ski's flexural and torsional rigidity more significantly than when using a conventional laminated wood core or a polyurethane core. For example, the reinforcements are made of only 600 g / m² of unidirectional glass fibers or 420 g / m² of unidirectional basalt fibers. In skis manufactured conventionally, the reinforcements are not unidirectional but are reinforced in both the warp and weft and have a total glass weight exceeding 700 g / m², and most often equal to or greater than 800 g / m².Thus, reducing the weight of fibers used results in a weight saving on the total weight of the ski, and also reduces the environmental impact by decreasing the proportion of non-recyclable material.

[0085] The invention also relates to a second embodiment illustrated in the figure 2 In this embodiment, the core 2000 it comprises three elements 200, 210 made of plywood. A central element of the second type 210 and two lateral elements of the first type 200, arranged on either side of the central element of the second type 210.

[0086] The element of the second type 210 is formed by a juxtaposition, along the transverse axis of the nucleus 2000, diapers 212 featuring wood fibers oriented along the axis of the core thickness 2000 and diapers 211 featuring wood fibers oriented along the longitudinal axis of the core 2000.

[0087] In practice, the element of the second type 210 consists of between 1 and 50 layers, preferably with an odd number of layers.

[0088] In the example of the figure 2 the element of the second type 210 It has a constant width of 60 mm along the entire length of the core and is made up of 5 layers 211, 212. In an example that gives good results on alpine skis, the element of the second type 210 can have 27 layers 211, 212, formed by 3 stringers of 9 layers 211, 212 of 2.2 mm each and also features a constant width of 60mm.

[0089] The width of the element of the second type 210 can be between 50 and 150 mm, can be constant over the entire length of the core and / or ski or vary along the longitudinal axis to follow the profile of the ski's sidecut or another profile.

[0090] Furthermore, the element of the second type 210can have a height between 1 and 50mm, depending on the type of board, advantageously variable along the longitudinal axis of the core 2000, to follow the core thickness profile 2000.

[0091] Elements of the first type 200 are formed by a stacking, along the axis of the core thickness 2000, diapers 201 featuring wood fibers oriented along the longitudinal axis of the core 2000 and diapers 202 featuring wood fibers oriented along the transverse axis of the core 2000.

[0092] In other words, the fibers of the diapers 201, 202 successive angles have an orientation in the plane at 0°, then 90°, then again 0° with respect to the longitudinal axis of the core 2000.

[0093] In practice, the elements of the first type 200 consist of between 1 and 10 layers, preferably with an odd number of layers.

[0094] In the example of the figure 2 the elements of the first type 200 are made up of a superposition of three layers 201, 202, 201.

[0095] The thickness of the elements of the first type 200 The thickness can range from 2 to 70 mm and can vary along the longitudinal axis of the core. 2000, in order to adapt to the thickness of the core 2000. Alternatively, the thickness of the elements of the first type 200 can be constant along the entire length of the core and preferably less than the thickness of the element of the second type 210 along the entire length of the core. In particular, the thickness of the elements of the first type 200 may be identical to the thickness of the element of the second type 210. Alternatively, the element of the second type 210 may have a height greater than that of the elements of the first type 200, typically, the element of the second type 210may protrude by 2 to 10 mm compared to the elements of the first type 200.

[0096] Furthermore, the elements of the first type 200 may exhibit a variable width along the longitudinal axis of the core 2000, as illustrated on the figure 8 , to follow the profile of the sideline. The width can therefore vary between 5 and 300 mm depending on the design.

[0097] The elements 200, 210 are glued together, for example using urea-formaldehyde, melamine, phenolic, or resorcinol glue. Alternatively, the elements 200, 210 can be separated by an intermediate bonding layer with a thickness between 0.1 and 1 mm. This intermediate layer can be made of a material belonging to the group of high-tenacity fibers such as glass fibers or basalt fibers.

[0098] In a third embodiment illustrated in figures 3 And 7the core 5000, 5200 It also includes an additional polyurethane element 310 forming an envelope enclosing the elements of the first and second type 100, 110.

[0099] For this purpose, the polyurethane element 310 It has a roughly parallelepiped shape, with its longer sides curved inwards to follow the sidecut of the ski. The thickness of the polyurethane element 310 is between 2 and 80 mm.

[0100] The polyurethane element 310 presents a first hollow 312 carved into the thickness of the polyurethane element 310. This first obvious 312 presents a rectangular shape whose length and width are less than the length and width of the polyurethane element 310. Typically, the distance between the longest edges of the first recess 312and the side edges of the polyurethane element 310 is between 0.5 and 3 cm. Similarly, the distance between the shorter edges of the first recess 312 and the front and rear edges of the polyurethane element 310 is between 3 and 15 cm.

[0101] The first one, obviously 312 is provided in the lower part of the polyurethane element 310 and opens at least at the level of its underside. Preferably, the first opening 312 is provided over a thickness of between 0.2 and 40 mm.

[0102] The polyurethane element 310 also presents at least one second hollow 311 also included in the thickness of the polyurethane element 310. This second one obviously 311 also presents a rectangular shape whose length and width are less than the length and width of the polyurethane element 310.Preferably, the distance between the longest edges of the first recess 312 and the side edges of the polyurethane element 310 is also between 0.5 and 3 cm. Advantageously, the first hollow 312 and the second one, obviously 311 are overlapped so that their positioning relative to the lateral edges of the polyurethane element 310 is identical.

[0103] The second one, obviously 311 presents a length greater than that of the first recess 312. Typically, the second one obviously 311 obviously extends beyond each side of the first one 312 over a length between 3 and 15 cm. Advantageously, the portions of the second hollow 311 which protrude on either side of the first one obviously 312 are the same length.

[0104] The second one, obviously 311 is provided in the upper part of the polyurethane element310 and opens at least at its upper surface. Preferably, the second one obviously 311 is provided over a thickness of between 0.2 and 40 mm.

[0105] In practice, the two hollows 311, 312 communicate with each other via the underside of the second one, obviously 311 and the upper face of the first recess 312.

[0106] The recesses can be obtained by molding and / or machining. As an example, the first one obviously 312 can be achieved by machining through the entire thickness of the polyurethane element 310 so as to open up at the level of the lower and upper faces of the polyurethane element 310. The second one, obviously 311 It takes the form of two recesses made on either side of the first recess. 312 on a thinner surface, so that the second hollow 311only opens at the top surface of the polyurethane element 310. The two lateral recesses can be made beforehand during the molding of the polyurethane element. 310 or by machining.

[0107] As illustrated on the figure 6 a board for sliding, such as a ski 5100, including a core 5000, 5200 of the invention includes a sole 140, at the ends of which are arranged the squares 130. A layer of high-tenacity metallic or fibrous reinforcement 180 is arranged between the squares 130, on the sole 140. For example, the reinforcing layer 180 is a polyester veil.

[0108] The polyurethane element 310 covers the reinforcement layer 180 on a width less than that of the sole 140, to allow the songs to be arranged 120,on either side of the polyurethane element 310. In the form of implementation of the figure 6 the songs 120 are almost the same height as the polyurethane element 310. Alternatively, the songs 120 may have a height that is lower or higher than that of the polyurethane element 310.

[0109] The polyurethane element 310 presents at least one obviously filled by the presence of an element of the first type 100 and an element of the second type 110 covering the element of the first type 100. A reinforcing layer 330 covers the polyurethane element 310, the songs and the element of the second type 110. Advantageously, at the level of the ski's ski skate 5100, a metal plate 160, preferably made of Titanal® or Zycral®, with a thickness between 0.1 and 2 mm, is inserted over the reinforcement layer 330to allow the ski and boot to separate.

[0110] A new layer of metallic or fibrous reinforcement 150 covers the upper and lateral walls of the core 5000, 5200. This reinforcing layer 150 is covered by a protective top 170 intended for the protection and decoration of skis 5100.

[0111] In conclusion, the invention enables the development of a core that gives a ski board excellent mechanical properties in compression, bending, and torsion by combining two elements of the first and second types, thus optimizing the board's mechanical strength in all three spatial dimensions. The resulting core is therefore more robust and allows for a reduction in the thickness and / or weight of the mechanical reinforcements typically added. Ultimately, the invention reduces the number of materials used in ski manufacturing and promotes the use of natural materials, leading to increasingly eco-designed skis that are more environmentally friendly and easier to recycle.

Claims

1. A core (1000, 1001, 1002, 2000, 3000, 4000, 5000) for a glide board (1100, 1200, 5100), comprising an upper face and a lower face intended to face the gliding sole (140), the lower face defining a plane (P) comprising a longitudinal axis oriented along the length of the board and a transverse axis oriented along the width of the board, the core (1000, 1001, 1002, 2000, 3000, 4000, 5000) having a thickness measured in a direction perpendicular to said lower face of the core (1000, 1001, 1002, 2000, 3000, 4000, 5000), said core (1000, 1001, 1002, 2000, 3000, 4000, 5000) comprising: - at least one plywood element (100, 200) of a first type comprising an alternation of layers (101, 201) having wood fibres oriented along the longitudinal axis and layers (102, 202) having wood fibres oriented along the transverse axis, and characterised by - at least one plywood element (110, 210) of a second type comprising an alternation of layers (111, 211) of wood fibres oriented along the longitudinal axis and layers (112, 212) having wood fibres oriented along the thickness of the core (1000, 1001, 1002, 2000, 3000, 4000, 5000).

2. The core according to claim 1, characterised in that the layers (101, 102, 201, 202, 111, 112, 211, 212) forming the plywood elements (100, 110, 200, 210) have a thickness of between 1 and 3 mm3. The core according to claim 1 or 2, characterised in that the elements (100, 110, 200, 210) of the first and second types each comprise an odd number of layers (101, 102, 201, 202, 111, 112, 211, 212).

4. The core according to any one of claims 1 to 3, characterised in that the elements (100, 110, 200, 210) of the first and second types are separated by an intermediate bonding layer.

5. The core according to any one of claims 1 to 4, characterised in that the elements (100, 110, 200, 210) of the first and second types are separated from an intermediate reinforcing layer (115) made of a material included in the group including metals, high tenacity fibres such as glass fibres and basalt fibres.

6. The core according to claim 5, characterised in that the intermediate reinforcing layer (115) comprises fibres oriented along the longitudinal axis and / or oriented along the transverse axis.

7. The core according to any one of claims 1 to 6, characterised in that it comprises an element (100) of the first type and an element (110) of the second type, the element (100) of the first type being at least partially covered by the element (110) of the second type.

8. The core according to claim 7, characterised in that at the median longitudinal level of the core (1000), the element (100) of the second type covers between 30 and 80%, or even 100%, of the upper face of the element (110) of the first type.

9. The core according to claim 7 or 8, characterised in that the element (100) of the first type has a constant thickness, the element (110) of the second type having a variable thickness to follow the thickness profile of the core.

10. The core according to any one of claims 7 to 9, characterised in that the element of the second type (110) has a constant width, the element of the first type (100) having a variable width to follow the profile of the dimension line.

11. The core according to claim 7 to 10, characterised in that the element (110) of the second type has a constant thickness, the element (100) of the first type having a variable thickness to adapt the thickness of the core.

12. The core according to any one of claims 1 to 6, characterised in that it comprises two elements (200) of the first type and one element (210) of the second type, the element (210) of the second type being disposed in the central zone of the core (2000), the elements (200) of the first type being disposed on either side of the element (210) of the second type.

13. The core according to claim 12, characterised in that the element (210) of the second type has a height greater than that of the lateral elements (200) of the first type.

14. The core according to claim 12 or 13, characterised in that at the median longitudinal level of the core (2000), the element (210) of the second type covers between 50 and 70% of the total width of the core (2000).

15. The core according to any one of Claims 12 to 14, characterised in that the element (210) of the second type has a constant width over the entire length of the core (2000), the elements of the first type (200) having a variable width to follow the profile of the dimension line.

16. The core according to any one of claims 7 to 9, characterised in that the elements of the first type (200) have a constant width over the entire length of the core (2000), the element of the second type (210) having a variable width to follow the profile of the dimension line.

17. The core according to claim 1, characterised in that the core further comprises a polyurethane member (310) having at least one recess (311, 312) arranged in the thickness of said polyurethane member (310), configured to allow insertion of the elements (100, 200, 101, 201) of the first and second types into the at least one recess (311, 312).

18. The glide board comprising a core according to any one of claims 1 to 17.