Sports device for sliding on surfaces

Abstract

Sports device (1) for sliding on surfaces, having a multi-layer structure comprising a core layer (2), and at least one further layer (3) that faces the surface during operation, wherein the core layer (2) extends substantially along an entire length of the sports device (1) and comprises a matrix material (4) and at least one layer (5) of fibres, wherein the core layer (2) has a central region (6) arranged substantially centrally along the length of the sports device (1), wherein the matrix material (4) is traversed by the at least one layer (5) substantially along the entire central region (6), and the matrix material (4) is a mineral construction material such as concrete, wherein the layer (5) of fibres has pretensioning.

Description

[0001] Sports equipment for gliding on surfaces

[0002] The invention relates to a sports device for sliding on surfaces according to the preamble of claim 1.

[0003] Sports equipment for gliding on surfaces is known in the art and includes, for example, skis such as alpine skis, cross-country skis, and touring skis, or even snowboards. This also includes water skis and wakeboards. Further sports equipment for gliding on surfaces will become apparent to those skilled in the art from these exemplary references. All such sports equipment has in common that it has mechanical properties tailored to its specific intended use. For example, alpine skis can be produced with a wide range of flexural and torsional stiffness to adapt them to the needs of skiers of varying skill levels. This also allows skis to be tailored to their intended use, for example, for deep snow, off-road, or on-piste skiing.Competition skis for ski races on ski slopes, for example, have particularly high bending and torsional rigidity in order to enable particularly fast cornering and ensure a high level of smoothness.

[0004] Traditionally, skis have a wooden core, the so-called core layer, onto which one or more layers of different materials are applied. At least one further layer, which forms the so-called base, faces the surface, or rather, the snow during use. Furthermore, a design layer is usually provided, which is applied to the side of the ski facing away from the snow. It is also known in the art to manufacture the core layer from other materials such as wood. For example, attempts have been made to replace the wood of the core layer with stone material coated with fibers. Such a ski is known from DE 202017 003 752 U1. This allows the mechanical properties of the ski to be easily adapted to the intended use.

[0005] A disadvantage of such solutions is that the core layer fatigues during operation due to the forces continuously acting on the ski. This causes the stone material known from DE 202017 003 752 U1 to begin to become brittle, changing its mechanical properties and reducing the bending and / or torsional rigidity of the ski constructed in this way. In the worst case, this leads to the core layer losing its cohesion and crumbling, causing the ski to bend in one or more places. Once this happens, the ski is unusable and can only be disposed of. The object of the present invention is to provide a sports device for gliding on surfaces that avoids these disadvantages of the prior art.

[0006] According to the invention, this is achieved by providing a sports device for sliding on surfaces having the features of claim 1.

[0007] The sports equipment according to the invention for sliding on surfaces has a multi-layer structure, comprising a core layer and at least one further layer facing the surface during operation. The core layer extends substantially along the entire length of the sports equipment and comprises a matrix material and at least one layer of fibers. The core layer also has a central region arranged substantially centrally along the length of the sports equipment. The matrix material is penetrated by the at least one layer substantially along the entire central region, and the matrix material is a mineral building material such as concrete. Furthermore, the layer of fibers has a prestressing effect.

[0008] By constructing the core layer in the central area of ​​the sports equipment from the matrix material and the prestressed layer of fibers, which penetrates the matrix material at least in the central area, the bending properties, i.e., the stress and strain properties, as well as the damping properties of the sports equipment in this central area can be specifically adapted to the respective application. Furthermore, the prestressing of the fiber layer generates additional compressive stresses, which prevent or significantly delay the formation of cracks under load. This also prevents or at least significantly delays the gradual breakage or crumbling of the matrix material. This improves the service life of the sports equipment.

[0009] Preferably, the central region extends substantially along the entire length of the sports equipment. This allows the mechanical properties in each area of ​​the sports equipment to be specifically tailored by combining the matrix material and the fiber layer.

[0010] According to a preferred embodiment of the sports equipment according to the invention, the core layer comprises a region on each side adjacent to the central region, which is made of a different material than the central region. This allows the central region to have different mechanical properties from the rest of the sports equipment. Preferably, the at least one layer of fibers is prestressed in a longitudinal and / or transverse direction of the core layer. This allows the torsional rigidity and flexural rigidity of the sports equipment to be varied.

[0011] Furthermore, the pre-tension of the at least one layer of fibers can vary along the longitudinal and / or transverse directions of the core layer. This allows different areas of the sports equipment to be pre-tensioned to different degrees.

[0012] The fiber layer can comprise, for example, plastic fibers, glass fibers, basalt fibers, aramid fibers, carbon fibers, and / or natural fibers such as bamboo fibers. The fibers are preferably combined into one or more fiber bundles and impregnated with, for example, epoxy resin. The impregnated fiber bundles are preferably sanded on their surfaces. The choice of fiber material can thus also achieve an adjustment of the stress and strain properties of the core layer.

[0013] The matrix material is preferably concrete with aggregates with a maximum diameter of 4 mm. This allows for a particularly fine-grained structure of the matrix material.

[0014] According to the preferred embodiment of the sports equipment according to the invention, the matrix material is interspersed with several layers of fibers, and at least two layers are prestressed. This allows the flexural strength of the sports equipment to be increased. Preferably, the at least two prestressed layers have different prestress directions and / or are prestressed to different degrees. This allows the flexural strength of the ski to be progressively increased.

[0015] According to the preferred embodiment, the sports equipment is a ski or a snowboard. Preferably, at least one ski binding or one snowboard binding is arranged in the area of ​​the ski or snowboard where the central region of the core layer is located.

[0016] Preferably, the prestress is selected such that the prestress in the fibers is greater than 0% and up to 60% of the fibers' breaking strength. Thus, the fibers can be only slightly stretched, thereby achieving fiber alignment.

[0017] The sports equipment according to the invention, as well as preferred and alternative embodiments, are explained in more detail below with reference to the figures. Figure 1 shows a sectional view of a sports equipment according to the invention with a core layer.

[0018] Figure 2 shows a schematic representation of the core layer in a top view. Figure 3 shows a schematic representation of the core layer in a side view.

[0019] A sports device 1 according to the invention for sliding on surfaces with a multi-layer structure is shown in a sectional view in Figure 1. The surface itself is not shown. As can be seen from Figure 1, the sports device 1 according to the invention comprises a core layer 2 and at least one further layer 3 facing the surface during operation. This layer 3 can, for example, be a sliding coating if the sports device 1 is designed as a winter sports device, such as a ski or snowboard. The core layer 2 extends essentially along the entire length of the sports device 1 and comprises a matrix material 4 and at least one layer 5 of fibers.The core layer 2 also has a central region 6 arranged essentially centrally along the length of the sports equipment 1, wherein the matrix material 4 is interspersed with at least one layer 5 essentially along the entire central region 6, and the matrix material 4 is a mineral building material such as concrete. Concrete that can be used within the scope of the invention also includes fine-grain concrete with a grain size of preferably less than 4 mm. The central region 6 of the core layer 2 can also be produced as a prefabricated part or from in-situ concrete. The layer 5 is also shown in Figures 2 and 3, which show the central region 6 in schematic representations from above and from the side. The layer 5 made of fibers also has a prestress.This prestress can be applied, for example, during the production of the core layer 2 by prestressing the layer 5 of fibers, for example using a tenter frame, a clamping device, or other aids, and then encapsulating it with the matrix material 4. The clamping device and / or the tenter frame preferably comprise one or more hydraulic cylinders for applying the prestress. This prestresses the core layer 2 in the central region 6, which is defined by the prestress applied to the layer 5 of fibers. This prestressing gives the sports equipment in the central region 6 tension, strain, and damping properties that can be adapted to the intended application of the sports equipment 1 during production of the sports equipment 1. This allows a range of sports equipment 1 with different properties to be produced using the same construction materials and the same method.This reduces the production costs of the sports equipment 1 according to the invention. This construction method allows for the production of very thin-walled cross-sections in the range of 8-12 mm with very high load-bearing capacities compared to wooden cross-sections, as well as higher torsional and flexural rigidity with adequate damping behavior. This depends on the number of fiber layers (5), their prestressing, and the fiber material. Durability is also very high, making it a cost-effective option over its lifetime compared to other building materials with these strength properties.

[0020] Preferably, the prestress is selected such that the prestress in the fibers is greater than 0% and up to 60% of the fibers' breaking strength. Thus, the fibers can also be only slightly stretched, thereby achieving fiber alignment. In particular, prestresses of 1%, 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, and 60%, and ranges between these values, can be provided. Furthermore, the fibers can be prestressed to different degrees in different spatial directions, for example, within the scope of the prestresses mentioned.

[0021] According to the preferred embodiment of the sports device 1 according to the invention, the central region 6 extends essentially along the entire length of the sports device 1. This allows the prestressing to be applied to the entire sports device 1 by means of the layer 5. Alternatively, the core layer 2 can comprise a region on each of the two sides adjoining the central region 6, which is made of a different material than the central region 6. For example, the regions adjoining the central region 6 can be made of fiberglass, wood, carbon, etc. The sports device 1 can also comprise a region adjoining the central region 6 on only one side, which is made of a different material than the central region 6.

[0022] The at least one layer 5 of fibers can be prestressed in a longitudinal direction L of the core layer 6, as shown in Figure 2, and / or in a transverse direction Q of the core layer 6. This allows the flexural strength and torsional rigidity of the sports device 1 according to the invention to be configured independently of one another. The prestress of the at least one layer 5 of fibers can also vary along the longitudinal direction L and / or the transverse direction Q of the core layer 2. This allows different regions of the sports device 1 to exhibit different mechanical properties.

[0023] According to the preferred embodiment of the sports equipment 1 according to the invention, the fiber layer 5 can comprise plastic fibers, glass fibers, basalt fibers, aramid fibers, carbon fibers, and / or natural fibers such as bamboo fibers. The mechanical properties of the selected fibers can be used to specifically shape the mechanical properties of the core layer 2. The fibers can also be in processed form. For example, the fibers can form a felt, a woven fabric, a knitted fabric, embroidered textiles, etc. Furthermore, the fiber layer can comprise bundled continuous fibers or multiple longitudinal fiber strands with or without transverse fiber strands. The layer can thus consist of or comprise bundled continuous fibers, a single fiber strand, multiple parallel fiber strands, or processed textiles such as woven fabrics, braids, knitted fabrics, and / or embroidered fabrics. The fibers can also be in the form of processed products such as rods or strands.In addition, the respective fiber bundles can be impregnated and / or have a treated surface, such as sanding, to improve the composite properties. The fibers are preferably sanded or unsanded carbon fiber strands.

[0024] The selected matrix material 4 is preferably a concrete with aggregate grains having a maximum diameter of 4 mm. This type of concrete is also referred to as fine-grained concrete or mortar. Alternatively, matrix materials such as earthenware can also be used. The matrix material 4 can also be interspersed with several layers 4 of fibers, as shown in Figure 3, with at least two layers 5 being prestressed. These at least two prestressed layers 5 can also have different prestress directions and / or be prestressed to different degrees.

[0025] As stated above, the sports device 1 can be a ski or a snowboard. However, the sports device according to the invention can also be, for example, a water ski, a wakeboard, and the like. Preferably, at least one ski binding or one snowboard binding is arranged in the area of ​​the sports device 1 designed as a ski or snowboard in which the central area 6 of the core layer 2 is located.

[0026] The core layer 2 provided within the scope of the present invention and its structure allow the production of very thin-walled cross-sections in the range of 8-12 mm with very high load-bearing capacities compared to wood cross-sections, as well as higher torsional and flexural rigidity with adequate damping behavior. This depends on the mechanical properties and the cross-sectional area of ​​the embedded fiber reinforcement, as well as the degree of prestressing, thus resulting in a new application in the ski sports equipment sector. Durability is also very high, thus representing a cost-effective option over its lifetime compared to other building materials with these strength properties.

[0027] The ski core, or core layer 2, has always been the heart of every ski. In the past, there were wooden skis, but the core has been made of wood ever since. The core is encased in high-quality materials to influence the ski's properties. Almost all high-quality skis are sandwich constructions. The camber of the ski is one of the most important properties for the ski's handling. To maximize this and other factors such as smoothness and elasticity, many types of wood have been used as natural materials. The layers above and below are varied using premium materials such as carbon and titanal. Deflection tests were conducted on test specimens of core layer 2. The test specimens had dimensions of approximately 10 cm in deflection length and 10 cm in width.

[0028] Eight different test specimens were subjected to the vibration test with different load levels. Test specimen PK6 is unreinforced, all other test specimens PK1 to PK5 were reinforced in two layers, with layer 5 comprising textile reinforcement made of carbon fibers impregnated with epoxy resin and made smooth or additionally sanded. There is also a wooden test specimen and a ski as a reference test specimen. Starting with "load level 0", in which the test specimens were tested unloaded and in a non-cracked state, the load was increased with each subsequent load level. In load level 1, the test specimens were loaded up to a defined force, during which the first cracks formed in all reinforced components. As the load increased, a change in the dynamic properties could be observed with the onset of crack formation in the textile-reinforced test specimens.On average, the vibration frequency after load excitation was approximately 8 Hz for the cracked test specimens at load level one. This represents a 35% decrease compared to the frequency in the uncracked state at load level zero, and at the same time, an approximation of the frequency of the ski test specimen. In the subsequent load levels two and three, it can be seen that the frequency of the test specimens, which did not fail due to the increased load, decreased only very slightly compared to load level one.

[0029] When measuring damping in the uncracked state, a damping coefficient between 0.004 and 0.01 was calculated for almost all concrete test specimens. The measurements at load level zero show that the concrete test specimens in the uncracked state behave more stiffly than the ski and wooden test specimens. As expected, the damping values ​​of the concrete test specimens increase significantly at load level one. In the further load levels two and three, it can be seen that for the test specimens that did not fail due to the increase in load, the damping coefficient does not increase any further compared to load level one, despite further cracking. In summary, it can be stated that the mean damping coefficient of the textile-reinforced concrete test specimens in the cracked state is 0.025.

[0030] The damping values ​​​​of the preliminary tests are in a similar order of magnitude to those of a conventional ski. However, the flexural rigidity of the textile-reinforced components in the cracked state is lower than that of comparable skis with a wooden core. This makes the freeride sector particularly suitable for a sports device 1 according to the invention. Within the scope of the invention, textile-reinforced core layers 2 are prestressed, whereby the matrix material 4 remains crack-free under load. This significantly increases the rigidity, which also opens up other areas of application, such as classic piste skis. Another advantage is that with a core made of textile-reinforced concrete, the layers above and below, also made of fibers such as carbon, have almost the same material properties. This allows them to interact as a unit.

Claims

Patent claims:

1. Sports equipment (1) for sliding on surfaces with a multi-layered structure, comprising a core layer (2) and at least one further layer (3) facing the surface during operation, wherein the core layer (2) extends substantially along the entire length of the sports equipment (1) and comprises a matrix material (4) and at least one layer (5) of fibers, characterized in that the core layer (2) has a central region (6) arranged substantially centrally along the length of the sports equipment (1), wherein the matrix material (4) is penetrated substantially along the entire central region (6) by the at least one layer (5), and the matrix material (4) is a mineral building material such as concrete, wherein the layer (5) of fibers has a prestress.

2. Sports equipment (1) according to claim 1, characterized in that the central area (6) extends substantially along the entire length of the sports equipment (1).

3. Sports equipment (1) according to claim 1, characterized in that the core layer (2) adjoins the central area (6) on both sides, each comprising an area which is made of a material different from the central area (6).

4. Sports equipment (1) according to one of claims 1 to 3, characterized in that the at least one layer (5) of fibers is prestressed in a longitudinal direction (L) of the core layer (2).

5. Sports equipment (1) according to one of claims 1 to 3, characterized in that the at least one layer (5) of fibers is prestressed in a transverse direction (Q) of the core layer (2).

6. Sports equipment (1) according to one of claims 1 to 5, characterized in that the pretension of the at least one layer (5) of fibers varies along a longitudinal direction (L) and / or a transverse direction (Q) of the core layer.

7. Sports equipment (1) according to one of claims 1 to 6, characterized in that the layer (5) of fibers comprises plastic fibers, glass fibers, basalt fiber, aramid fibers, carbon fiber and / or natural fibers such as bamboo fibers.

8. Sports equipment (1) according to one of claims 1 to 7, characterized in that the matrix material (4) is a concrete with aggregate particles which have a maximum diameter of 4mm.

9. Sports equipment (1) according to one of claims 1 to 8, characterized in that the matrix material (4) is permeated by several layers (5) of fibers, and at least two layers (5) have a prestress.

10. Sports equipment (1) according to claim 9, characterized in that the at least two prestressed layers (5) have different prestressing directions and / or are prestressed to different degrees.

11. Sports equipment (1) according to one of claims 1 to 10, characterized in that the sports equipment (1) is a ski or a snowboard.

12. Sports equipment (1) according to claim 11, characterized in that at least one ski binding or one snowboard binding is arranged in that area of ​​the ski or snowboard in which the central area (6) of the core layer (2) is located.

13. Sports equipment (1) according to one of claims 1 to 12, characterized in that the pretension is selected such that the pretension of the fibers is more than 0% and up to 60% of the breaking strength of the fibers.

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