SPORTS DEVICE FOR SLIDING ON SURFACES

Abstract

A sports equipment (1) for sliding on surfaces having a multi-layered structure comprising a core layer (2) and at least one further layer (3) facing the surface in use, the core layer (2) extending essentially along an entire length of the sports equipment (1) and comprising a matrix material (4) and at least one layer (5) of fibres, wherein the core layer (2) has a central region (6) arranged essentially centrally along the length of the sports equipment (1), with the matrix material (4) being interspersed with the at least one layer (5) essentially along the entire central region (6), and the matrix material (4) is a mineral construction material such as concrete, with the layer (5) of fibres exhibiting pre-tensioning.

Claims

1. A sports equipment (1) for sliding on surfaces having a multi-layered structure comprising a core layer (2) and at least one further layer (3) facing the surface in use, the core layer (2) extending essentially along an entire length of the sports equipment (1) and comprising a matrix material (4) and at least one layer (5) of fibres, characterized in that the core layer (2) has a central region (6) arranged essentially centrally along the length of the sports equipment (1), with the matrix material (4) being interspersed with the at least one layer (5) essentially along the entire central region (6), and the matrix material (4) is a mineral construction material such as concrete, with the layer (5) of fibres exhibiting pre-tensioning.

2. The sports equipment (1) according to claim 1, characterized in that the central region (6) extends essentially along an entire length of the sports equipment (1).

3. The sports equipment (1) according to claim 1, characterized in that the core layer (2) comprises one area each on both sides adjacent to the central region (6), the area being made of a material which is different from the central region (6).

4. The sports equipment (1) according to claim 1, characterized in that the at least one layer (5) of fibres is pre-tensioned in a longitudinal direction (L) of the core layer (2).

5. The sports equipment (1) according to claim 1, characterized in that the at least one layer (5) of fibres is pre-tensioned in a transverse direction (Q) of the core layer (2).

6. The sports equipment (1) according to claim 1, characterized in that the pre-tensioning of the at least one layer (5) of fibres varies along a longitudinal direction (L) and/or a transverse direction (Q) of the core layer.

7. The sports equipment (1) according to claim 1, characterized in that the layer (5) of fibres comprises synthetic fibres, glass fibres, basalt fibres, aramid fibres, carbon fibres and/or natural fibres such as bamboo fibres.

8. The sports equipment (1) according to claim 1, characterized in that the matrix material (4) is a concrete with aggregate grains which have a maximum diameter of 4 mm.

9. The sports equipment (1) according to claim 1, characterized in that the matrix material (4) is interspersed with several layers (5) of fibres, and at least two layers (5) exhibit pre-tensioning.

10. The sports equipment (1) according to claim 9, characterized in that the at least two pre-tensioned layers (5) have pre-tensioning directions that are different from each other and/or are pre-tensioned to different degrees.

11. The sports equipment (1) according to claim 1, characterized in that the sports equipment (1) is a ski or a snowboard.

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

13. The sports equipment (1) according to claim 1, characterized in that the pre-tensioning is selected such that the pre-tensioning of the fibres is more than 0% and up to 60% of the breaking strength of the fibres.

Description

[0018] The sports equipment according to the invention, as well as preferred and alternative embodiment variants, are explained in further detail below with reference to the figures.

[0019] FIG. 1 shows a sectional view of a sports equipment according to the invention with a core layer.

[0020] FIG. 2 shows a schematic illustration of the core layer in a top view.

[0021] FIG. 3 shows a schematic illustration of the core layer in a side view.

[0022] A sports equipment 1 according to the invention for sliding on surfaces with a multi-layered structure is shown in a sectional view in FIG. 1. The surface as such is not illustrated. As can be seen in FIG. 1, the sports equipment 1 according to the invention comprises a core layer 2 and at least one further layer 3 facing the surface in use. This layer 3 can be, for example, a sliding coating, if the sports equipment 1 is designed as a winter sports equipment, such as a ski or snowboard, for example. The core layer 2 extends essentially along an entire length of the sports equipment 1 and comprises a matrix material 4 and at least one layer 5 of fibres. In addition, the core layer 2 has a central region 6 arranged essentially centrally along the length of the sports equipment 1, wherein the matrix material 4 is interspersed with the at least one layer 5 essentially along the entire central region 6, and the matrix material 4 is a mineral construction material such as concrete. Concrete that can be used within the scope of the invention is also fine-grained concrete having a grain size of preferably less than 4 mm. Furthermore, the central region 6 of the core layer 2 can be manufactured as a prefabricated part or from in-situ concrete. The layer 5 is also depicted in FIG. 2 and FIG. 3, which show the central region 6 in a schematic illustration from above and from the side. Furthermore, the layer 5 of fibres exhibits pre-tensioning. This pre-tensioning can be applied, for example, in the course of producing the core layer 2 by pre-tensioning the layer 5 of fibres, for example with a stretching frame, a clamping device or other aids, and subsequently pouring the matrix material 4 around it. The clamping device and/or the stretching frame preferably comprise(s) one or several hydraulic cylinders for applying the pre-tensioning. As a result, the core layer 2 in the central region 6 receives a pre-tensioning, which is defined by the pre- tensioning applied to the layer 5 of fibres. Due to this pre-tensioning, the sports equipment obtains stress, stretch and damping properties in the central region 6, which can be adapted to the planned application of the sports equipment 1 during the production of the sports equipment 1. As a result, a number of pieces of sports equipment 1 with different properties can be produced using the same construction materials and the same method. This reduces the production costs of the sports equipment I according to the invention. Using this construction method, 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 bending stiffness with adequate damping behaviour can be produced, this depending on the number of layers 5 of fibres, their pre-tensioning and the material of the fibres. The durability is also very high and thereby constitutes a variant that is economical throughout the service life, in comparison to other construction materials with such strength properties.

[0023] Preferably, the pre-tensioning is selected such that the pre-tensioning in the fibres is more than 0% and up to 60% of the breaking strength of the fibres. Thus, the fibres can also be stretched only slightly, whereby a fibre orientation is achieved. In particular, pre-tensions of 1%, 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55% and 60% and ranges between these values can be provided. In addition, the fibres can be pre-tensioned in different spatial directions to different degrees, for example within the scope of the pre-tensions as mentioned.

[0024] According to the preferred embodiment of the sports equipment 1 according to the invention, the central region 6 extends essentially along an entire length of the sports equipment 1. As a result, the pre-tensioning can be applied to the entire sports equipment 1 by means of the layer 5. Alternatively, the core layer 2 can comprise one area each on both sides adjacent to the central region 6, the area being made of a material which is different from the central region 6. For example, the areas adjacent to the central region 6 can be manufactured from fibreglass, wood, carbon, etc. The sports equipment 1 can also comprise an area on only one side adjacent to the central region 6, the area being made of a material which is different from the central region 6.

[0025] The at least one layer 5 of fibres can be pre-tensioned in a longitudinal direction L of the core layer 6, as can be seen in FIG. 2, and/or in a transverse direction Q of the core layer 6. As a result, the bending strength and the torsional stiffness of the sports equipment 1 according to the invention can be designed independently of each other. Furthermore, the pre-tensioning of the at least one layer 5 of fibres can vary along the longitudinal direction L and/or the transverse direction Q of the core layer 2. As a result, different areas of the sports equipment 1 can have different mechanical properties.

[0026] According to the preferred embodiment variant of the sports equipment 1 according to the invention, the layer 5 of fibres can comprise synthetic fibres, glass fibres, basalt fibres, aramid fibres, carbon fibres and/or natural fibres such as bamboo fibres. Due to the mechanical properties of the selected fibres, the mechanical properties of the core layer 2 can be designed in a purposeful manner. The fibres can also exist in a processed form. For example, a felt, a woven fabric, a knitted fabric, embroidered textiles, etc. can be formed by the fibres. In addition, the layer of fibres can comprise bundled continuous fibres, or several longitudinal fibre strands with or without transverse fibre strands. The layer can thus consist of or comprise bundled continuous fibres, a single fibre strand, several parallel fibre strands, processed textiles such as woven fabrics, interlaced fabrics, crocheted fabrics, knitted fabrics and/or embroidered fabrics. The fibres can also exist in the form of processed products such as rods or braids. In addition, the respective fibre bundles can be impregnated and/or can also have a processed surface, such as, for example, sanding, to improve the bond properties. The fibres are preferably sanded or unsanded carbon fibre strands.

[0027] The selected matrix material 4 is preferably a concrete with aggregate grains which have a maximum diameter of 4 mm. Concrete of this kind is also referred to as fine-grained concrete or mortar. Alternatively, matrix materials such as, for example, earthenware can also be used. As can be seen in FIG. 3, the matrix material 4 can also be interspersed with several layers 4 of fibres, with at least two layers 5 exhibiting pre-tensioning. Furthermore, these at least two pre-tensioned layers 5 can have pre-tensioning directions that are different from each other and/or can be pre-tensioned to different degrees.

[0028] As explained initially, the sports equipment 1 can be a ski or a snowboard. However, the sports equipment according to the invention can also be, for example, a water ski, a wakeboard and the like. Furthermore, at least one ski binding or one snowboard binding is preferably arranged in the area of the sports equipment 1 designed as a ski or snowboard in which the central region 6 of the core layer 2 is located.

[0029] Due to the core layer 2 provided within the scope of the present invention and its structure, 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 bending stiffness with adequate damping behaviour can be produced, which depends on the mechanical properties and the cross-sectional area of the embedded fibre reinforcement, as well as the degree of pre-tensioning, whereby a new application in the sports equipment sector of skis is created. The durability is also very high and thereby constitutes a variant that is economical throughout the service life, in comparison to other construction materials with such strength properties.

[0030] The ski core or even the core layer 2 of the ski has always been the centrepiece of every ski. Wooden skis existed in the past, afterwards and up until today, the core has been made of wood. The cladding of the core is made with high-quality materials in order to influence properties of the skis. Almost all high-quality skis are sandwich structures. The pre-tensioning of the ski is one of the most important properties for the running characteristics of the skis. In order to maximize these and other factors such as smooth running and elasticity, many types of wood have already been used as natural materials. The layers above and below are varied with first-class materials such as carbon and titanal.

[0031] Swing-out tests were conducted on test objects of a core layer 2, with the test objects having dimensions of a swing-out length of approx. 1 m and a width of approx. 10 cm.

[0032] Eight different test objects were subjected to the swing-out test with different load levels. The test object PK6 is unreinforced: all other test objects PK1 to PK5 have been reinforced in a double-layered manner, with the layers 5 comprising textile reinforcements made of carbon fibres, which have been impregnated with epoxy resin and designed so as to be smooth or, respectively, sanded in addition. Furthermore, there is a test object made of wood and a ski as a reference test object. Starting with load level 0, in which the test objects were examined while being unloaded and in a non-cracked state, the load was increased with each subsequent load level. At load level 1, the test objects were loaded up to a defined force, in which case the first cracks formed in all reinforced components. In doing so, as cracks began to form in the textile-reinforced test objects, a change in the dynamic properties could be observed as the load increase progressed. On average, the frequency of the vibration after load excitation was around 8 Hz for the cracked test objects at load level one. This is a decrease of 35% compared to the frequency in the non-cracked state at load level zero and at the same time an approximation to the frequency of the ski test object. In the test objects in which no failure has happened due to the load increase, it is evident that, at the further load levels two and three, the frequency has decreased only very slightly in comparison to load level one.

[0033] When damping was measured in the non-cracked state, a damping level of between 0.004 and 0.01 was calculated for almost all concrete test objects. The measurements at load level zero show that the concrete test objects in the non-cracked state exhibit a more rigid behaviour than the ski and wooden test objects. As expected, the damping values of the concrete test objects made of concrete increase significantly at load level one. In the test objects in which no failure has happened due to the load increase, it is evident that, at the further load levels two and three, the damping level does not increase any further in comparison to load level one, despite further cracking. In summary, it can be stated that the mean value of the damping level of the test objects made of textile-reinforced concrete is 0.025 in the cracked state.

[0034] The damping values of the preliminary tests are of an order of magnitude similar to that of a conventional ski. With the textile-reinforced components, however, the bending stiffness is lower in the cracked state than with comparable skis having a wooden core. As a result, the freeride sector is particularly suitable for a sports equipment 1 according to the invention.

[0035] Within the scope of the invention, textile-reinforced core layers 2 are pre-tensioned, as a result of which the matrix material 4 remains crack-free under load. Consequently, the stiffness increases considerably, whereby other areas of application, such as classic piste skis, for example, can also be opened up. Moreover, it is an advantage that, with a core made of textile-reinforced concrete, the layers located above and below, which are also made of fibres such as carbon, have almost the same material characteristics. Hence, they can interact as a unit.