FR2718648A1 - Ski and its manufacturing process. - Google Patents

Abstract

The ski which is made of composite material has a sliding plate (1) edged with side squares (10) . Along its length it carries superposed sub-assemblies (11,12,14,15) fixed to each other by a visco-elastic sheet or plate interface (16) with an inverted V section. The visco-elastic sheet is located in the median neutral fibre plane of the ski thickness. The maximum thickness of the ski is greater than 26 mm. The lower and upper sub-assemblies are made of polyurethane or one in polyurethane and the other of wood. The cores (11,12) of the sub assembly are surrounded by a fabric sheath (14,15) pre-impregnated with a thermal hardening resin, such as epoxide. The visco-elastic sheet shows through the lateral edges of the ski. The two sub assemblies and the visco elastic sheet are encompassed in a shell (13) .

Description

SKI AND METHOD OF MANUFACTURING

  The invention relates to a new type of ski, including downhill skiing, or even cross-country skiing, preferably but not limited to having a non-planar upper profile. It also concerns

  manufacturing processes of this type of ski.

  The profile of the skis, originally very traditional, since of substantially rectangular cross section or even trapezoidal, has substantially evolved to result in skis of varying shapes, including a non-planar top, giving for example a

triangular cross section.

  Although this evolution of the alpine skis certainly responds to the goal of optimizing the qualities, especially the responsiveness of these skis, it has also been found that they can cause a general weakening of the ski structure, and particularly breaks

or delaminations.

  These break phenomena are also more pronounced, since we adopt a more complex skiing profile varying the

  distance from the neutral fiber, increasing in some areas this distance in a dangerous way.

  In a modern ski made in composite structure, taking into account the elastic limit of the materials used as reinforcements, the limit thickness of the ski, capable of giving it properties of sufficient resistance to the maximum tensile and compressive stresses during flexural stresses , is of the order of 26 mm. In such a ski, and because of the steel edges used, the neutral fiber is located substantially at 40 ° C.

  % of ski thickness starting from the sole.

  Moreover, the current trend in the realization of alpine skis, leads to a general tightening of the ski, in a concern of acquiring more precision in turns. The corollary to this

  Closeness of the ski is constituted by the elevation of the feet of the skier.

  Indeed, because of this tightness, during a turn, the risk increases to see the shoe on the snow, and not the edges of the ski, translating almost inevitably by a skid of the ski, which can also cause the fall. By increasing the thickness of the ski, we

  cancel, if not reduce this risk, because we move the shoe away from the snow.

  There is thus an antinomy between this concern to increase the thickness of the skis, and the risks incurred in terms of resistance to breakage of the skis.

structure that constitutes them.

  The invention proposes to make a thick ski of composite material, able to overcome these phenomena of breaks and delaminations. This ski, whose thickness at the level of the pad is greater than 26 mm, is made in two main parts, that is to say comprising two subsets, respectively a lower main subset, and an upper secondary subset. , extending substantially over the entire bearing length of the ski, the subassemblies being secured to one another by means of a sheet or plate

  made of a viscoelastic material.

  In US Pat. No. 5,232,241 there is described a ski whose upper face has a recess intended to receive a plate comprising the fasteners, namely the front stop and the heel piece, this plate being bonded to the overall structure of the ski by introducing at the interface a viscoelastic material. In fact, this plate, called "fixing", is partially damped with respect to the vibrations generated by the progression of the ski on the snow. Moreover, because of the particular shape of the recess, and the complementary shape of said plate, the role of the intermediate element in viscoelastic material is necessarily

  limited to the only depreciation function.

  FR-A-2 670 392 and 2 675 391 have also been proposed an alpine ski comprising, on the one hand, the ski proper and, on the other hand, a stiffener, shorter than the contact surface of the ski with the snow, and attached to a portion of the upper face of the ski, the actual ski and the stiffener further comprising at their interface a layer of flexible elastic or visco-elastic material to provide damping functions. The stiffener used has the function of limiting inflections and aims to oppose the excessive opening of the ski. It thus fulfills here only a function of adjustment in bending, partially modified by the damping action of the plate of material

viscoelastic.

  Document FR-A-2 237 653 describes a composite ski incorporating, within its structure, and under the filler novau, a layer made of a material with a high modulus of elasticity, attached to an elastomer layer, intended to to fill only the damper function. As a result, the elastomer layer, placed inside the reinforcing elements, with respect to the neutral fiber, provides no solution to the phenomena

delamination and breakage.

  In other words, no element of the prior art taught a solution to allow the use of skis made of composite materials, of relatively large thickness, in any case, much greater than the thicknesses conventionally used, and starting from skis of more complex profile. The ski according to the invention is constituted, on its bearing length, of two superimposed subassemblies, secured to one another by means of an interface constituted by a sheet or a plate made of a visco-elastic material , glued along its length to each of these two subassemblies. It is characterized in that the sheet or plate of viscoelastic material is located approximately at the level of

  median plane of ski thickness.

  In this way, two mechanized ski webs are obtained one over the other, allowing shearing phenomena of the upper subassembly on the lower subassembly without leading to the delamination phenomenon of the reinforcement elements constituting the mechanization. of each subset. In fact, it is thus possible to make skis of relatively large thickness without fearing the occurrence of the phenomena of

rupture and delamination.

  Advantageously, said median plane integrates the neutral fiber of the ski.

  In this way, said plate or sheet of viscoelastic material is located at the level of the neutral fiber, said neutral fiber being traditionally defined as being the zone at which the

  compressive and tensile stresses.

  According to some embodiments of the invention, the interface between the two subassemblies is not flat, but can adopt a profile

  any, and for example inverted V.

  The two subassemblies, respectively lower and upper, both comprise a novau made of polyurethane, or one of polyurethane and the other of wood, or even of other substitute materials, each core having at least one element reinforcement constituted either by a fabric or a sheet of glass fibers, carbon or aramid (KEVLAR - registered trademark), or by a metal strip pre-impregnated with a thermosetting resin, in particular to

to promote his collage.

  Each of the subassemblies is advantageously constituted of a

  core surrounded by a sheath of woven material, advantageously

  impregnated with a thermosetting resin, such as an epoxy resin.

  In an advantageous embodiment of the invention, the band of viscoelastic material is flush with the edges laterally.

ski.

  In another embodiment of the invention, the two sub-

  sets and the intermediate element constituted by the plate of viscoelastic material are included in a shaped shell,

supporting the decor.

  The invention also relates to a method for making such a ski.

  This method is characterized in that the constituent subassemblies of the ski are directly made according to the desired profile, then placed in a mold, with the interposition of an interface of viscoelastic material pre-glued with a resin, the cohesion of the final constitutive structure of the ski being obtained by raising the temperature of the mold, liquefying said pre-impregnation resin and revealing its adhesion qualities. The cores are made either by machining or by injection of polyurethane in a specific mold. The two cores entering the structure

  the same ski can be of identical or different natures.

  In another embodiment, the lower subassembly previously produced in the final form is placed in a mold in the form of the sole and edge elements, and then the sheet is put in place. a layer of viscoelastic material, then these elements are capped by a shell having reinforcing elements at its upper internal face, and finally, the polyurethane is injected in order to form the upper core inside. space between the shell and the viscoelastic material sheet. In a variant of this embodiment, the sheet of viscoelastic material is covered with a reinforcing strip

  prior to injection of polyurethane.

  The way in which the invention can be realized and the advantages which result from it will emerge better from the following realization elements.

  given by way of indication and not limitation in support of the appended figures.

  FIG. 1 is a schematic representation in perspective of a

  ski with a variable profile embodying the invention.

  FIGS. 2 and 3 are diagrammatic representations in cross-section of a ski with a traditional profile, according to two forms of

  different embodiments according to the invention.

  FIGS. 4 and 5 are schematic cross-sectional representations of the ski shown in FIG. 1, according to two forms

different embodiments.

  FIG. 6 is a schematic representation in cross section of a ski, according to the profile of FIG. 1, being molded,

  performed according to another embodiment of the invention.

  FIG. 7 is a schematic representation in cross section of a ski, being molded, made according to another

  method of carrying out the invention.

  The ski shown in Figure 1 comprises firstly a gliding sole (1), extending between its two ends, respectively rear (2) (heel) and front (3) (spatula). This ski can be totally hulled, that is to say, styling the ski from one edge to the other, as furthermore represented in FIGS. 2 and 4, or with partial hulls (FIGS. 3 and 5), or to

  contrary more traditional and, in this case includes side chants.

  The ski shown in FIG. 1 has a particular profile, for example

  elsewhere described in French Application No. 93.06807 of the Applicant,

  that its upper face (4), which in this case must be understood as being the surface extending from the upper end of a side edge to the other when these exist, or directly from a metal edge to the other when it is a hull ski, is raised and has at least one upper edge (5), defining in fact two slopes respectively (6) and (8), inclined relative in terms of the surface of the sole. In fact, any cross section of this type of ski is substantially shaped

  triangular, as can be seen in Figures 4, 5, 6 and 7.

  According to one characteristic of the invention, the thickness of this ski, in particular at the level of the shoe (9), ie the thickest central zone of the ski at which the bindings are located, is

  greater than 26 mm, and for example 28 mm at its thickest point.

  In addition, according to another essential feature of the invention,

  the internal structure of the ski basically comprises two sub-

  each having a core, respectively (11) and (12), extends

  over the entire load-bearing length of the ski, secured to each other,

  by bonding, at their common interface, said interface

  receiving in addition a sheet or plate (16) of a viscoelastic material

  than. The carrying length of a ski is defined as the distance

  on the sole separating the two front and rear contact lines of the ski.

  The two subassemblies integrating the cores (11) and (12) are thus

  likely, because of the existence of this sheet or plate of visco-

  resilient (16), to move very slightly relative to each other, in other words to allow shearing movement of the upper part of the ski relative to the lower part, without generating phenomena of rupture or delamination, which the skis hitherto known did not make it possible to obtain, given the rigidity of the stacks, therefore the non-elastic relative shear,

say non-destructive.

  This fundamental result thus makes it possible to produce skis of relatively large thickness or with an improved profile such as the profile

  shown in Figures 1, 4, 5, 6 and 7.

  According to a first embodiment of the invention, the two cores (11) and (12) are made of polyurethane, each of said cores being surrounded by a fabric sheath respectively (14) and (15), playing the role of reinforcing element, and constituting with said novax (11, 12) the lower and upper subsets. The polyurethane cores can advantageously be made before the actual realization of the ski, either by machining or by injection

in a specific mold.

  In the example described with reference to FIG. 3, the ski proper is finalized at a mold, in which the sole (1), typically made of polyethylene and two lateral metal edges, is firstly put in place. (10). The first core (11) provided with its fabric sheath (14) pre-impregnated with a thermosetting epoxy resin is

  then placed on the sole (1) between two vertical edges (7).

  The viscoelastic material interface (16) is then placed flat on the upper face of the core (11) and the edges (7). The upper core (12) is then positioned also provided with a fabric sheath (15) pre-impregnated with a thermosetting resin, in particular an epoxy resin, on said interface (16). The assembly is then covered for example with a shaped shell (13), supporting the decor. The mold is then closed and heated to such a degree as to result in a quasi-liquefaction of the pre-impregnation resins, making it possible to develop their adhesive properties, and thus to ensure the

cohesion of the whole.

  This bonding occurs on the one hand, between the sole and the edges (1, 10) and the lower subassembly (11, 14), then between the sheath (14) and the songs

  (7), then between the lower subassembly (11, 14) and the visco-

  elastic strap (16), and then between said viscoelastic plate (16) and the

  upper assembly (12, 15) and finally between the sheath (15) and the outer shell

(13).

  In the example described in Figure 2, the ski is a ski section typically trapezoidal. However, this ski may have a rectangular profile as described in FIG. 3, or alternatively have a variable profile as shown in FIGS. 1, 4, 5, 6 and 7, and so have a triangular section whose characteristics dimensions of each

  faces are likely to vary throughout the ski.

  The production method described in connection with FIGS. 2, 4 and 5 is identical to the preceding one, except that this ski has no side edges, and that the shell (13) covers the two subassemblies to come practically resting on the edges (10). It is quite possible to replace the polyurethane core in a wood core (19) or equivalent,

  as shown in Figure 4.

  In addition, the viscoelastic material is not necessarily plane and parallel to the soleplate (1), as shown in FIGS. 2, 3 and 4, but may adopt a particular, more adapted profile. depending on the profile

  ski as shown in Figure 5.

  In fact and according to an essential characteristic of the invention, the interface (16) of viscoelastic material adopts a shape such that it allows its positioning as close as possible to the median plane of the thickness of the ski, and advantageously of the neutral fiber of the ski, and this, in order to optimize the shear conditions of the ski even when the ski is highly-stressed so as, on the one hand, reduce the risk of delamination, and secondly , increase the characteristics of

responsiveness of the ski.

  In addition, the properties, in particular the mechanical properties of the interface film (16) made of viscoelastic material, are capable of varying according to its

  the length of the ski, in order to optimize its role of authorizing

  shearing in areas of greatest stress.

  According to another embodiment of the invention (see FIG. 6), after placing the preformed lower core (11) and wrapped in a sheath (14) on the sole (1) and the edges (10) on the inside the mold

  (20), and then positioning the visco-elastic interface (16) on said sub-

  lower assembly (11, 14), and finally positioning on said interface (16) a sheath (15) fabric, inside which is another stretchy and waterproof sheath (17), the whole being capped with a preformed shell (13) or a sheet intended to subsequently form the shell (13), the mold is closed by means of the lid (21), then the injection of the constituents (polyol and isocyanate) d a polyurethane foam inside said sheath (17), which in contact with each other, react in a known manner and expand in such a way as to fill the void space conferred by the shell ( 13) to form in situ the

  second upper core (12), and where appropriate, the shell (13).

  In another embodiment of the invention, more specifically shown in FIG. 7, the sole (1) and the edges (10) are positioned on the inside of a mold (20, 21). lower assembly (11, 14) in a similar manner to the example described above, and on which one comes to position flat the interface (16) visco elastic,

  a layer of a reinforcing element (18) is placed on its upper face.

  A sheet is then placed in place after making the ski to form a shell (13), said sheet being provided at its upper internal face with a layer of a reinforcing element (22). It is proceeded to the closing of the mold (20, 21) and finally to the injection of polyurethane within the free space formed between the interface (16) and the sheet (13), so as to realize the core higher (12). In case of incompatibility, in particular chemical or adhesive between the polyurethane and the impregnating resins of the reinforcing elements (18) and (22), it is possible to set up a sheath (17) tight and stretchable on said interface ( 16) prior to closing the mold (20, 21), and within which

  is actually injected polyurethane.

  When the ski is thus made, the edges of the reinforcing element (22) are not in contact with the reinforcing element (18) and even more so the interface (16), so as to create at this level a discontinuity of the reinforcements, to facilitate the shearing phenomena of the upper subset relative to the lower subset on either side of

the interface (16,18).

  On the other hand, when the outer shell (13) includes the two sub-

  lower and upper assemblies, without presenting a rupture, ie discontinuity at the interface (16) (see FIGS. 2, 4, 6, 7), the shearing occurring at the level of said viscoelastic interface (16) is resumed by the plasticity of the material constituting the shell: polyethylene,

ABS, etc ......

  Thus, such a ski made in this way, has great possibilities in terms of bending, while allowing the use of relatively large thickness structure and improved profiles,

  variables, such as in particular the ski described in connection with Figure 1.

: _3

Claims (14)

  1 / Ski made of composite material, comprising a gliding sole (1), optionally bordered with side edges (10), and constituted over its entire bearing length of two subassemblies (11, 12, 14, 15) superimposed, secured to one another via an interface constituted by a plate or sheet (16) of a viscoelastic material glued over its entire length to each of said subassemblies, characterized in that the sheet or plate (16) of viscoelastic material is located   approximately at the median plane of ski thickness.   2 / ski according to claim 1, characterized in that the median plane integrates the neutral fiber of the ski, so that said plate or sheet of viscoelastic material (16) is located at the level of the neutral fiber of the ski.   3 / Ski according to one of claims 1 and 2 characterized in that its   maximum thickness, in particular at the level of the pad is greater than 26 millimeters, and in that it is   4 / Ski according to one of claims 1 to 3, characterized in that   the interface of viscoelastic material (16) adopts any profile, and especially inverted V.   5 / ski according to one of claims 1 to 4, characterized in that the   two subassemblies, respectively lower (11, 14) and upper (12,), are made of polyurethane, or one of polyurethane and the other of   wood, or even other substitute materials.   6 / Ski according to claim 5, characterized in that each of the cores (11, 12) constituting the subsets is surrounded by a sheath (14, 15) of woven material, preferably pre-impregnated with a resin   thermosetting, and in particular epoxy resin.   7 / Ski according to one of claims 1 to 6, characterized in that the   sheet or plate (16) of viscoelastic material is flush with the lateral songs of the ski.   8 / Ski according to one of claims 1 to 6, characterized in that the   two subassemblies (11, 12, 14, 15) and the intermediate element constituted by the plate of viscoelastic material (16) are included   in a shaped shell (13) supporting the decor.   9 / Ski according to one of claims 1 to 8, characterized in that the   mechanical properties of the interface (16) made of viscous material   elastic vary according to its location relative to the length of the ski.   10 / A method for producing a composite ski consisting of two superimposed subassemblies (11, 12, 14, 15) secured to one another via an interface constituted by a plate or sheet (16) in a viscoelastic material, glued over its entire length to each of said subassemblies, characterized in that the subassemblies (11, 12, 14, 15) are directly made according to the desired profile, and then square   in a mold, with the interposition of the interface (16) made of viscous material   pre-glued elastic of a resin, the cohesion of the final structure constituting the ski being obtained by raising the temperature of the mold, liquefying said pre-impregnation resin and revealing its adhesion qualities.   11 / A method for producing a composite ski consisting of two superimposed subassemblies (11, 12, 14, 15) secured to one another via an interface constituted by a plate or sheet (16) in a viscoelastic material, glued over its entire length to each of said subsets, characterized in that it consists: - firstly to achieve the lower subassembly (11, 14) according to its profile final; then positioning said subassembly (11, 14) within a shaped mold on the gliding base (1) optionally bordered with edges (10), to which it is secured by gluing; - then to place flat on the subassembly (11, 14) a plate or sheet of a visco-elastic material (16); - Then to cover these elements by a shell (13); then to close the shaped mold; and finally, injecting into the space provided between the interface (16) and the shell (13) the constituents of a polyurethane foam, which in known manner react and expand to fill the whole of said   space, to form the upper core (12).   12 / A method of producing a ski according to claim 11, characterized in that the shell (13) is capable of extending from a song to the other, or from one square to the other.   13 / Method for producing a ski according to one of claims 11   and 12, characterized in that the shell (13) comprises at its upper internal face a reinforcing element (22), which, when the ski is   realized, does not reach the level of the interface (16).   14 / Method for producing a ski according to one of claims 11   at 13, characterized in that the injection of the constituents of the polyurethane is carried out inside a stretchable and leakproof plastic sheath (17), in particular to said constituents, previously positioned flat on the plate or sheet (16) of viscoelastic material. / Method for producing a ski according to one of the   Claims 11 to 14, characterized in that the interface (16) receives on its   upper side, prior to injection of the polyurethane, an element reinforcement (18).