EP0785000A1 - Snowboard with sole having honeycomb depressions - Google Patents

Abstract

The ski or snowboard has a series of concave indentations (4) in its under surface (2), made e.g. from a polymer with a low or high molecular weight. The indentations are circular, elliptical or ovoid in shape, and they number between 6 and 200 in the board's surface. The depth of each indentation is between 0.2 and 3 mm, and has a diameter of between 2 and 60 mm. The indentations are made by thermal moulding during the assembly stage of the board's different components, by hot imprinting with a rotary tool which has equally-spaced bosses on its surface, or by machining with a rotary cutter of appropriate convex shape.

Description

The invention relates to a sliding board intended to operate on snow or on ice, in particular, a ski of the alpine type, a monoski or else a snowboard. The invention relates more precisely to the improvement of the sliding surface of such a board by the realization of a particular structuring and the methods making it possible to achieve such an improved structuring.

Today, the practice of sliding on snow-covered slopes has evolved towards a search for pleasure of ease and escape in off-piste, powdery or on specially equipped terrain such as "snow parks" for the evolution of surfers in free-style. The notions of speed and pure performance are becoming marginal in the practice of skiing and only concern the narrow area of competition. These concepts no longer make sense at all in certain disciplines such as freestyle snowboarding.

In this discipline, the surfers never evolve in a straight line and are not constrained to any obligation of passage between stakes. In their travels, they perform many sliding or aerial figures.

In skiing, users are looking above all for extreme maneuverability and ease in pristine terrain away from the "boulevards" slopes.

To improve the performance of skis with the previous aim of promoting sliding on traditional skis, it has been necessary to carry out a longitudinal structuring or grooving of the sliding sole. By breaking the water film in a unidirectional way, the sliding power of the plastic layer in contact with snow has been considerably increased. On the other hand, the main drawback of this type of structure for the new skiing and snowboarding practices mentioned above is to hinder lateral gliding by making the board much more directive (this effect not being sufficiently sensitive in the context of traditional practices of ski).

Structures in parallel grooves and oriented in the preferred direction of the board and having this disadvantageous directional effect, are proposed, for example, in the document DE 961 335.

One of the aims of the present invention is to adapt the structure of the sole to the practice of new glides, in particular for snowboarding, but also for skiing when it is practiced on very varied terrains. as in deep snow and in powder or on poorly groomed tracks (skis widened in tip and heel and narrowed in skate thus conferring a dimension line in very pronounced wasp size).

The principle is generally, to seek to reduce the directive effect of the ski by not breaking the film of water in a unidirectional manner but in a multidirectional manner so as not to favor any direction. Thus, the board becomes more mobile and manageable by being able to slide in all directions over 360 °.

For this the invention relates to a gliding board for evolution on snow, characterized in that it comprises a sliding sole on which are distributed several imprints of cells whose outline is a closed convex curve.

In addition to the sliding effect favored in a multidirectional way, the suction effects in the case of wet snow, which dramatically increase the coefficient of friction, are greatly reduced thanks to the significant reduction in surface in contact with snow. Therefore, the ski or snowboard can be detached from the snow more easily to perform tricks.

These fingerprints also have the role of absorbing the reception of jumps, in particular in snowboarding on hard terrains. Indeed, at the time of landing, the air trapped in the hollows is compressed and gives a damping effect.

More precisely, the outline of the cavities of the cells has a shape of a circle, an ellipse or an ovoid shape.

Preferably, the cavities of the cells have a shape of a spherical portion or of a portion of ellipsoid of revolution.

The imprints can be obtained by thermoforming the sole during the assembly cycle of the various constituents of the board; by providing shaped bosses in the mold cavity.

Other characteristics and advantages of the invention will be better understood with the aid of the description which follows and with reference to the appended drawings.

Figure 1 is a bottom view of a snowboard.

Figure 2 is a sectional view of a cavity imprint executed in the sole.

Figure 3 is a simplified view of an embodiment of the invention.

Figure 4 is a view of another embodiment of the invention.

Figure 5 is a bottom view of a south according to a variant.

The snowboard 1 shown in Figure 1 consists of an elongated body in a preferred direction II 'with a sliding sole 2 and side edges 3 bordering the sides of the sliding sole. The sole generally consists of high or low molecular weight polyethylene. The soles with high molecular weight have longer molecular chains therefore more solid and which allow a better absorption of the waxes. The sole has generally a thickness varying from 0.4 to 2 mm and is glued to the rest of the structure of the board.

The invention therefore consists in providing for the production of indentations or recesses in the form of concave cells 4 in the thickness of the sliding sole 2. The contour of the cells forming part of the plane of the sole is that of a curve at any point convex and closed without sharp angles so as not to favor, or at least to privilege in a particular direction.

The distribution and the number and size of cells can be variable depending on whether one wishes to promote the desired effect at such or such a place on the board or on the contrary limit this effect.

In general, the number of cells is between 6 and 200. The distribution can be uniform over the entire surface of the board or, on the contrary, be concentrated in certain areas such as in the area of the bindings where the pressure is maximum.

As shown in Figure 2, the imprints have the shape of a spherical portion of radius R depending on the depth e between 0.2 and 3 mm. The diameter D of the imprint is between 2 and 60 mm.

The spherical shape leads, thanks to perfect symmetry, to not favor any particular direction of the orientation of the imprint. The interruption of the water film therefore takes place indifferently during a displacement in the direction II 'and during a sliding displacement perpendicular to II' or in a direction more or less inclined relative to I-I ', by example.

In addition to the effect of improving the glide, during the aerial evolutions of the surf, the support on the air is more stable thanks to the turbulence created locally around the alveoli. The control of figures in the air is thus improved. Amortization during receptions is also another advantage already discussed above.

Another advantage is the improvement of the grip when taking the edge to execute a turn. This is a surprising effect which has been observed in numerous tests carried out and which finds two additional explanations. On the one hand, when the imprints are made near the edges, the surface in contact with the snow when the surf or the ski is in edge grip, becomes smaller than in the absence of a cell. As a result, the pressure is concentrated on the edge essentially; from which it results in better attachment.

On the other hand, after carrying out the surfing or skiing, finishing operations are traditionally carried out which consist in passing one or more times, the sliding surface in contact with a Corundum wheel. The board is driven by a drive device, at a given running speed and when the rotary wheel comes into contact with a transverse area of the sole where there are several imprints distributed over the width of the sole, the surface the contact of the grinding wheel with the sole is reduced. There is therefore creation of overpressure in these places during machining, and the grinding wheel therefore tends to sink deeper into the sole and the edges. This results in a phenomenon of transverse ripples, including on the edges, which a little like a serrated knife blade provides a more aggressive grip on snow or ice. This effect is more noticeable on a ski than on a surf due to the higher pressure of the wheel due to the narrowness of the board.

FIG. 3 illustrates a way of making the imprints according to the invention by a thermoforming technique in a mold.

We take advantage of the heat and pressure exerted during the assembly cycle of the various constituents of the surf or ski in a forming or assembly mold to obtain thermoforming of the cavities of the cells.

The components of the board are therefore stacked such as the core 10, the lower 11 and upper 12 reinforcements based on epoxy resin prepregs as well as the decoration top 13 and the polyethylene sole 2 in an assembly mold 5. Des bonding films can be interposed between the elements if necessary. The part of the mold 5 in contact with the sole comprises bosses in the form of spherical portions obtained by machining during the manufacture of the mold cavity. The mold is closed and a baking cycle is applied at a determined temperature, at a given pressure and a determined time to obtain the assembly of the components together by crosslinking the resin of the reinforcements and the thermofusion of the bonding films. . Concomitantly, one obtains by thermoforming of the polyethylene the execution of the imprints at the locations of the bumps 50. At these locations, the lower reinforcement 11 based on fibers and epoxy resin is capable of being easily deformed. During the crosslinking of the resin, there is hardening and preservation of the form in this deformed state.

After leaving the mold, the ski or snowboard must then undergo the traditional finishing operations; namely deburring, grinding, belt sanding, etc.

Figure 4 illustrates an alternative embodiment of the imprints. Before assembly with the other constituents, the sole 2 in the form of a strip is driven and guided by a drive and guide device formed by cylinders 70, 71, 72 and strip 73. A rotary tool 8 comprising bosses 80 distributed uniformly over its contact surface with the sole, hot prints the shape of the imprints in the sole material. The tool can advantageously consist of a cylinder regulated at the polyethylene forming temperature of the sole, ie around 160 ° C. More precisely, the contour can take the form of a circle (perfect symmetry), an ellipse (two axes of symmetry orthogonal) or any ovoid shape (zero or an axis of symmetry only).

Another alternative embodiment also consists in machining recesses of the cavities of the cells after manufacture of the gliding board. Using a cutter having a suitable convex shape, the impressions are hollowed out to the desired dimensions in the sole.

Of course, the production of other shapes of cells can be envisaged as shapes of portion of ellipsoid of revolution or other complex shapes.

FIG. 5 illustrates a variant in which the cells have an elliptical contour with a first axis of symmetry oriented in the longitudinal direction of the board and a second axis of symmetry perpendicular to the first axis of symmetry.

Of course, the invention is not limited to the embodiments thus described and includes all the technical equivalents which may fall within the scope of the claims which follow.

Claims (8)

Snow gliding board, characterized in that it comprises a sliding sole (2) on which are distributed several imprints of cells (4) whose outline is a closed convex curve. Snow gliding board according to claim 1, characterized in that the contour of the indentations (4) of the cells has a shape of a circle, an ellipse or an ovoid shape. Snow gliding board according to claim 2, characterized in that the cavities of the cells (4) have the shape of a spherical portion or of portion of ellipsoid of revolution. Snow gliding board according to claim 1, 2 or 3, characterized in that the number of cells is between 6 and 200. Snow gliding board according to any one of the preceding claims, characterized in that the depth (e) of each cavity imprint (4) is between 0.2 and 3 mm; the diameter (D) being between 2 and 60 mm. Gliding board according to claim 3, characterized in that the imprints (4) are obtained by thermoforming of the sole (2) during the assembly cycle of the various constituents (10, 11, 12, 13, 2) of said board ; by providing shaped bosses in the mold cavity (5). Snow gliding board according to claim 3, characterized in that the imprints (4) are obtained by hot printing of a rotating tool (8) comprising bosses (80) distributed uniformly over its surface. Snow gliding board according to claim 3, characterized in that the indentations (4) are machined in recovery with milling cutters having an appropriate convex shape.

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