Land vehicles – Ski or skate appliance or attachment – Ski pole
Patent
1993-07-20
1994-09-20
Camby, Richard M.
Land vehicles
Ski or skate appliance or attachment
Ski pole
135 65, 428 361, A63B 5312
Patent
active
053483464
DESCRIPTION:
BRIEF SUMMARY
The invention relates to a ski stick, whose stem portion is formed of a hollow reinforced-plastic profile.
Ski sticks are known, in which the stem portion is formed of a hollow reinforced-plastic profile. Usually, the reinforced-plastic profile has a circular profile by cross-section, which may also taper towards the other end.
Ski-stick structures are also known, which have a longitudinal cross-sectional profile deviating from a circular form. Thus, e.g. in the DE patent publication 1728575 ski sticks have been described, which have different non-circular, e.g. elliptic cross-sections. A profile with an elliptic cross-section has a good stiffness on the plane of the longer diameter of the cross-section, but a poor stiffness on the plane of a shorter cross-sectional axis. It is also more difficult to mechanically manufacture profiles with an elliptic cross-section. Possibly for these reasons, ski sticks with an elliptic cross-section have not been seen on the market.
The present invention relates to a ski stick, which comprises a hollow reinforced-plastic profile, which is reinforced such that the profile has an excellent stiffness both in the direction of the cross-sectional longer axis and in the direction of the shorter axis, and which profile is extremely easy to manufacture mechanically into exact dimensions. Another certain inventive object is to achieve a ski stick, whose lightness, bending strength and durability clearly exceed the ski-stick solutions known.
Thus, the inventive ski stick having a hollow reinforced-plastic profile is characterized in that the profile wall includes at least one reinforcement element extending in the longitudinal direction, which is at least partially embedded in the manufacturing step of the reinforced-plastic profile in a wall structure as an integral part thereof.
Such a structure is previously unknown in ski sticks. It is on the other hand known in the manufacture of hollow profiles to support the profile with different reinforcement structures from the inside. E.g. in the DE patent publication 3017336, it is known to manufacture mast profiles of sailing boats, inside which are fixed rods formed by fibers extending in the longitudinal direction and having a high tensile strenth. However, the manufacture of the profiles described in the publication is very cumbersome, since the rods are fixed to the inner side of the profile by gluing between different extensions and grooves. By means of the method described, it may be possible to manufacture profiles having only a considerably large transverse surface, and the gluing is not necessarily succesful. An essential difference between the inventive profile and the mast profile described in the DE publication, if fairly different applications and dimensional differences are not taken into account, is the fact that the reinforcement element is fixed according to the DE publication to a completed profile afterwards (bu gluing), and it does not form an integral part of the wall structure of the profile, which integral part is fixed in position at the same time as the profile has been manufactured.
According to a certain preferred embodiment of the invention, the ski-stick profile is manufactured by means of a pultrusion process, wherein the profile is formed on top of said reinforcement element or elements. Such a pultrusion is e.g. a tape winding pultrusion method, in which on top of a central core to be used as an inner mold are placed reinforcement fibers wetted with a binder, around the central core covered with fibers is tightly wound a tape, the binder is hardened by means of heat or radiation, and finally, the central core and the tape are removed for obtaining a hollow tube profile having a generally smooth outer surface.
Said process may be applied to the manufacture of the inventive ski-stick profiles in a manner described in the Finnish patent application FI 915981 as being modified such that the inventive reinforcement profiles are caused to come into contact with the central core before embedding said fibers or
REFERENCES:
patent: 3972529 (1976-08-01), McNeil
patent: 4301201 (1981-11-01), Stout
patent: 5024866 (1991-06-01), Goode
Camby Richard M.
Neste Oy
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