Note: Descriptions are shown in the official language in which they were submitted.
21 65677
Ski
The invention relates to a ski having layers of transparent plastic
material.
Besides the technical properties of a ski and in particular those
relating to the way in which the ski runs, the appearance of the ski is
also having an increasing influence on the purchase decision. In that
respect there are various means, including those of a technical nature
which are used to influence the appearance of the ski. Thus for example
transparent layers are already used as cover layers for the top side of the
ski or as running surface coverings for protecting the decoration or
decorative layers which are disposed either on the rear side of the
transparent layer or beneath the transparent outside layer.
The object of the present invention is to expand the use of transparent
ski components, more specifically on the one hand to influence the
appearance of the ski and/or on the other hand in order thereby also to
achieve a technical effect.
In accordance with the invention that is achieved in that the entire
ski body is transparent at least in a region-wise manner. There is
therefore not just a surface layer or running surface layer that is
transparent, in order to be able to see decorations, symbols or graphics
which are disposed therebeneath or therebehind respectively, but in
accordance with the invention the ski as such, that is to say in its
entirety, is transparent, at least in a region-wise manner. That means in
particular that the ski is transparent at least perpendicularly to the
plane of the running surface over its entire cross-sectional height, which
however does not have to be the case at all locations of the ski
(accordingly "at least in a region-wise manner"). For example functional
parts of opaque material, in particular metal, as in the case of alpine
skis the steel edges, binding fixing parts or reinforcing elements, can
form zones which are excluded from being transparent. It is also possible
for decorative reasons or for identification purposes to provide in the ski
body inserts which are opaque, that is to say not transparent, and which
2 1 65677
then form contrasting zones with respect to the transparent regions of the
ski.
"Transparent" in accordance with the invention means not only clearly
see-through but also translucent. A measurement in respect of transparency
is the transmission coefficient r = ~d/~o (~0 = incident radiation intensity
and ~d = transmitted radiation intensity). Therefore, in accordance with
the present invention, those locations of the ski where the transmission
coefficient in the visible spectral range is different from zero, for
example is at least 10 % but preferably considerably above that value, are
to be identified as "transparent". A light source which is disposed for
example beneath the running surface of the ski should still at least be
perceived as a gleam of light on the surface of the ski. The transparency
can also be a "coloured" transparency, that is to say it does not have to
extend over the full width of the visible spectrum. On the other hand
however changes in colour due to radiation (light, UV) or ageing are rather
undesired. Transparent materials which are of maximum stability in
relation to radiation and ageing, in terms of their transparency, should
therefore be used.
In contrast to the above-mentioned known state of the art it is not
sufficient in accordance with the invention that only the surface layers
comprise transparent plastic material, but also the inner components must
be transparent at least in a region-wise manner, thus for example the load-
bearing layers which can comprise glass fiber-reinforced plastic material
by transparent glass fibers being bonded with transparent synthetic resin.
If the reinforcing inlays partially comprise transparent glass fibers and
partially opaque carbon fibers, it is also possible to achieve particular
effects from the technical and design-configuration points of view. The
core zones of the ski can be kept transparent either by using transparent
core material or by forming internal cavities. For that purpose for
example the load-bearing ski body may be formed from one or more hollow
bodies whose walls (at least in part) comprise transparent glass fiber-
reinforced plastic material. Another possibility would be to arrange a
honeycomb core with upright honeycomb cell walls which then also permit a
view therethrough perpendicularly to the running surface of the ski if the
honeycomb cell walls themselves do not comprise transparent material. It
will be appreciated however that the honeycomb cell walls may also comprise
21 65677
plastic material which is possibly glass fiber-reinforced.
The requirement in respect of transparency also applies in relation to
any adhesives which may be used for joining the individual layers, in which
respect it will be noted that it is also possible to use non-transparent
S adhesives in a zone-wise manner.
The invention not only makes it possible to produce skis of hitherto
unknown appearance but it also guarantees a view into the interior of the
ski in order to detect any workmanship flaws, for example defective
orientation of the glass fibers or air bubbles in hardened synthetic resin.
Composite fiber plastic materials with directed reinforcing fibers can
fully exhibit their excellent material properties such as high strength,
stiffness and resistance to corrosion, only when the arrangement is such
that the fibers are oriented in accordance with the loading. Just minor
deviations in the fiber direction relative to the loading direction give
rise to serious losses in terms of the strength of the component. Hitherto
monitoring the correct orientation of the reinforcing fibers during ski
manufacture failed either for technological reasons or because the
individual ski components did not permit an inspection (were opaque). The
composite fiber materials were then intentionally over-sized in order to
compensate for a possible loss of strength, although of course at the
expense of overall weight.
The structure of a ski which is transparent in itself permits
continuous monitoring of the fiber orientations and thereby makes it
possible to achieve the optimised use of composite fiber materials, which
in turn is necessary for lightweight constructions.
The invention can be applied to all kinds of skis (alpine skis, cross-
country skis, water skis etc.), in which respect the term ski also embraces
other pieces of equipment such as snowboards.
The invention is described in greater detail hereinafter by means of
an embodiment with reference to the drawing.
Figures 1, 3 and 5 are views in cross-section of different embodiments
of skis and Figures 2, 4 and 6 are the associated plan views of the skis.
Figure 1 is a view in cross-section of a ski which, with a suitable
selection of material, in accordance with the invention, can be in the form
of a transparent ski.
The ski shown in Figure 1 belongs to the general kind of shell-type
- 21 65677
skis and comprises a flat lower structural group with the running sole 1,
for example of polyethylene, and the lateral steel edges 2. The interior
of the ski is enclosed laterally and upwardly by a shell 3 of non-
reinforced plastic material. The internal load-bearing structure of the
ski is formed by a hollow body 4 with walls 5, 6 of fiber-reinforced
thermoplastic or thermosetting plastic material. The inner hollow body 4
fills the internal space between the upper shell 3 and the lower structural
group 1, 2 in such a way that the outside walls 5 bear against the inside
walls of the shell 3 and the lower structural group 1, 2 respectively. The
hollow body 4 also has perpendicular intermediate walls 6 which subdivide
the interior of the hollow body 4 into three air-filled hollow chambers.
In order to achieve the transparency in accordance with the invention
of the ski body, a transparent polyethylene is used for the sole 1 and a
transparent plastic material, for example a UV-stabilised thermoplastic
material such as for example thermoplastic polyurethane or polyamide is
also used for the shell 3. Also used for the walls 5, 6 of the hollow body
4 are transparent synthetic resins, for example polyester resin or epoxy
resin as a bonding agent for the fiber inlays, wherein the fiber inlays
entirely or predominantly comprise transparent glass fibers.
Such a ski could then be of the appearance as shown in Figure 2, in
plan view, in which case the ski body is transparent from above downwardly
in the regions A, while the edge zones B, and also the tip and end regions
C, D as well as the binding fixing region E appear non-transparent
(opaque), more specifically as a result of the presence of the steel edges
2 and also the tip and end protection of metal and a reinforcing inlay or
binding fixing plate in the binding fixing region. The tip protection
could for example also consist of a so-called fit-on tip, in which case the
fit-on tip can also be at least partially transparent and in particular can
comprise transparent and preferably thermoplastic material.
Additional dark longitudinal strips also make their mark on the
appearance of the transparent ski (Figure 4) if, as shown in Figure 3, for
example longitudinally extending inserts or inlays 7 for example of
synthetic resin-bound carbon fibers are arranged on the top side of the
inner hollow body 4. In the case shown in Figure 3 the inlays 7 are of a
triangular cross-section and are arranged over an intermediate wall 6.
The embodiment shown in Figures 5 and 6 also provides that the
21 65677
appearance of the transparent ski has dark opaque strips F which however
are now formed by flat strip-shaped inserts or inlays 8 between the top
side of the inner hollow body 4 and the shell 3. In addition, in the
embodiment shown in Figures 5 and 6, also interwoven in the fiber
reinforcements of the two lateral chambers, which fiber reinforcements also
comprise a tubular glass fiber weave, are individual threads 9 of carbon
fibers, for example disposed in an inclined position (in a helical
configuration), which then appear as a dark zig-zag pattern or crossed
pattern G.
Manufacture of a ski in accordance with the illustrated embodiments can
be effected using a mold consisting of two mold halves, the ski being
shaped ;n the cavity of the mold, involving the following process steps:
a) the components of the lower structural group (running sole and steel
edges) are fitted into the recess of the first (lower) mold half;
b) flat fiber material portions impregnated with synthetic resin, in
tubular form, are provided with internally disposed tubes of air-tight
material and positioned in the mold, being for example laid onto the
components of the lower structural group, which components have been
fitted into the first mold half;
c) the possibly pre-shaped cover foil of plastic material is also
positioned in the mold;
d) the second (upper) mold half with a mold cavity corresponding to the
lateral and surface contour of the ski body is fitted onto the first
mold half;
e) the internally disposed air-tight tubes within the tubular synthetic
resin fiber material portion or portions are inflated with compressed
air, in which case they expand, and the tubular synthetic resin fiber
material portion or portions is or are also expanded and the foil bears
against the inside wall of the second mold half; and
f) the synthetic resin of the tubular synthetic resin fiber material
portion or portions is hardened, while the internal compressed air
pressure is maintained in the internally disposed air-tight tube or
tubes, possibly with the application of heat.
After termination of the hardening operation the increased pressure
produced by the compressed air in the tubes is released and the ski is
removed from the mold. After the ski is removed from the mold, any edges
21 65677
of the cover foil which still project beyond the side surfaces of the lower
component group are cut off. With suitable provision being made at the ski
tip and/or the rear end of the ski, the tubes can be removed from the
internal cavities of the hollow bodies which have now hardened, for the
purposes of re-use thereof. If the tubes remain in the ski body they must
be at least partially transparent, for example consist of transparent
polyamide, having regard to the effect in accordance with the invention.
The illustrated embodiments of transparent skis and the described
example of a possible production process are obviously not to be
interpreted in a restrictive sense but only as individual examples of
numerous possible ways of carrying into effect the inventive concept of a
transparent ski.
