Title:
MULTILAYER SKI AND METHOD FOR THE FABRICATION THEREOF
United States Patent 3698731


Abstract:
There is disclosed a multilayered ski construction which contains at least one strip-, band- or similar shaped insert member and/or support member formed of a preferably cross-linked, elastomeric plastic material, which possesses a relative dampening of at least 8 percent, preferably 10 percent (measured in accordance with the flexural wave technique at 100 Hz). The invention also relates to the method of fabrication of such ski or the like.



Inventors:
Jost, Wolf-dieter (Oberosterreich, OE)
Moritz, Karl-gunter (Oberosterreich, OE)
Application Number:
04/883519
Publication Date:
10/17/1972
Filing Date:
12/09/1969
Assignee:
SEMPERIT OSTERREICHISCH-AMERIKANISCHE GUMMWERKE AKTIENGESELLSCHAFT
Primary Class:
Other Classes:
525/126, 525/131
International Classes:
A63C5/056; A63C5/07; A63C5/12; (IPC1-7): A63C5/12
Field of Search:
280/11.13 260
View Patent Images:
US Patent References:
3537717DAMPED SKI AND METHOD OF MAKINGNovember 1970Caldwell
3475035POLYCARBONATE PLASTIC SKISOctober 1969Nason
3432451POLYOLEFIN-MODIFIED POLYURETHANES AND PROCESS OF MAKING SAMEMarch 1969Kales
3374001Metallic skiMarch 1968Baudou
3358052Polyurethane composition containing 0.2 to 5% polyolefin or polystyreneDecember 1967Acher, Jr. et al.
3352566Composite metal and plastic ski and method for making sameNovember 1967Kennedy
3322435SkiMay 1967Kirschner
3310604Polyurethanes having dispersed therein high and low molecular weight polyolefinsMarch 1967Steingiser et al.
3194572Laminated skiJuly 1965Fischer
3170972Method of extruding a polyurethane articleFebruary 1965Knipp et al.
2992939Adhesive process and laminatesJuly 1961Larson et al.
2581532SkiJanuary 1952Hem



Primary Examiner:
Betts, Kenneth H.
Assistant Examiner:
Smith, Milton L.
Claims:
What is claimed is

1. A multilayered ski comprising at least one member formed of an elastomeric plastic material which possesses a relative dampening of at least 8 percent (measured in accordance with the flexural wave technique at 100 Hz), and wherein the layers of said ski are elastically preloaded and completely encased by the dampening material.

2. A multilayered ski as defined in claim 1, wherein said relative dampening is preferably at least 10 percent.

3. A multilayered ski as defined in claim 1, wherein said elastomeric plastic material is preferably cross-linked.

4. A multilayered ski as defined in claim 1, wherein said one member is an insert member.

5. A multilayered ski as defined in claim 1, wherein said one member is a support member.

6. A multilayered ski as defined in claim 1, wherein said ski layers are selected from the group comprising glass fiber reinforced plastic and aluminum.

7. A multilayered ski as defined in claim 1, wherein said dampening material is a highly filled rubber mixture.

8. A multilayered ski as defined in claim 1, wherein said dampening material is a semi-rigid polyurethane elastomer.

9. A multilayered ski comprising at least one member formed of an elastomeric plastic material which possesses a relative dampening of at least 8 percent (measured in accordance with the flexural wave technique at 100 Hz), and wherein said at least one member of said ski comprises a runner surface possessing a coating formed of said dampening material.

10. A multilayered ski as defined in claim 9, which possesses a core formed as said dampening material.

11. A multilayered ski as defined in claim 10, wherein said core is a profiled member.

12. A multilayered ski as defined in claim 11, wherein said profiled member is equipped with recesses at its underside.

13. A multilayered ski as defined in claim 9, wherein said dampening material contains approximately 5 percent to 50 percent by weight of a polyolefin.

14. A multilayered ski as defined in claim 13, wherein said polyolefin is preferably approximately 10 percent to 20 percent by weight.

15. A multilayered ski as defined in claim 13, wherein said dampening material contains polyethylene.

16. A multilayered ski as defined in claim 15, wherein said polyethylene preferably possesses a low melting point.

17. A multilayered ski as defined in claim 9, wherein said dampening material is a semi-rigid polyurethane elastomer.

18. A multilayered ski comprising at least one member formed of an elastomeric plastic material which possesses a relative dampening of at least 8 percent (measured in accordance with the flexural wave technique at 100 Hz), and wherein said at least one member comprises side edges formed of said dampening material.

19. A multilayered ski as defined in claim 18, wherein said dampening material is a semi-rigid polyurethane elastomer.

20. A multilayered ski comprising at least one member formed of an elastomeric plastic material which possesses a relative dampening of at least 8 percent (measured in accordance with the flexural wave technique at 100 Hz), and wherein said dampening material possesses additives for improving the sliding properties of the ski.

21. A multilayered ski as defined in claim 20, wherein said additives are selected from the group comprising silicone, powdered graphite, and molybdenum sulfide.

22. A multilayered ski as defined in claim 20, wherein said dampening material is a semi-rigid polyurethane elastomer.

23. A multilayered ski comprising at least one member formed of an elastomeric plastic material which possesses a relative dampening of at least 8 percent (measured in accordance with the flexural wave technique at 100 Hz), and wherein the surface of said dampening material is treated so as to possess good sliding properties.

24. A multilayered ski as defined in claim 23, wherein said dampening material is a semi-rigid polyurethane elastomer.

25. A multilayered ski comprising at least one member formed of an elastomeric plastic material which possesses a relative dampening of at least 8 percent (measured in accordance with the flexural wave technique at 100 Hz), and wherein good sliding properties are imparted to the surface of said dampening material by fluorination.

26. A multilayered ski as defined in claim 25, wherein said dampening material is a semi-rigid polyurethane elastomer.

Description:
BACKGROUND OF THE INVENTION

The present invention broadly relates to the field of skiing and, more specifically, relates to an improved multi-layered ski construction as well as to an improved method for the fabrication thereof.

For a long, long time suitably formed wooden strips have been used as the runners for skiing. However, it soon became apparent that, not only for the purpose of improving the weight distribution of the skier over the entire length of the runner, but also for a more positive guiding of the skier, especially when skiing in curves, it is advantageous to slightly arch or curve the ski upwardly in order to impart thereto an elastic pre-stress or pre-loading. Since, in particular, ash became known as an elastic wood, it was ash, in addition to Swedish birch, hickory and the like, from which skis were preferably manufactured.

Furthermore, it was found that with a simple, even if somewhat pre-formed wooden strip, the elasticity was not sufficient, since the elastic pre-loading quickly diminished under the loading by the skier and, additionally, too little resistance was applied to the sudden loads which occur in different situations. Consequently, the skis oftentimes ruptured or broke. The problems were countered through the utilization of multi-layered glued skis, which oftentimes were built and are still built as individual strips, ledges or the like of different wood types. Further advancement in the fabrication of skis was brought about in the last few years through the use of glass fiber reinforced plastic laminates, which especially serve to considerably reduce both of the previously mentioned problems.

But with the increasing elasticity of the runners -- even when preventing too pronounced embrittlement -- still new problems arose, especially with the modern skiing technique and because of the increased speed of skiing. The very long slightly upwardly arched and very elastic skis, especially their tips and rear ends, begin to flutter and vibrate at the slightest irregularities, especially upon partially lifting the skis from the surface, such occurrence cannot be prevented during modern day skiing and the pistes which are used today. However, such fluttering and vibrations impair the smooth running and stability of the ski as well as its guiding capability.

Indeed, previously attempts were made to cope with these problems. However, the few solutions which have been proposed therefor have not brought about really satisfactory results. Among such solutions are, for instance, the use of a dampening torsion rod arranged between the binding and the ski tip as taught by the Austrian Pat. No. 187,028; and the wave-like or profiled cover sheets or wedge or liner inserts, for instance, formed of glass fiber reinforced polyester resin or wood, which supposedly have a resilient and dampening action, as such have been taught in Austrian Pat. Nos. 235,180, 244,817 or 264,341. Also, the core filling proposed in Austrian Pat. No. 194,764 and possessing an inert organic filler results in a rapid pulverization of this filler material due to the movements of the skis, and therefore, has not been utilized in practice.

Previously, ski manufacturers and designers of skis tended to concentrate essentially upon improvements in the rupture strength, bending strength, bending stiffness and longevity of the elastic properties. Yet, even a change of the bending stiffness in different zones over a length of the ski does not provide any solution of the dampening problem.

SUMMARY AND DESCRIPTION OF THE INVENTION

Accordingly, it is a primary object of the present invention to provide an improved ski construction which overcomes the aforementioned drawbacks of the prior art.

Still, another more specific object of the present invention relates to improved multi-layer ski construction and method for the fabrication thereof, which overcomes the prior art disadvantages herein discussed.

Now, the invention proposes a multi-layer ski which is generally manifested by the features that it contains at least one strip-, band- or similar shaped insert- and/or support member formed of a preferably cross-linked, elastomeric plastic material possessing a relative dampening of at least 8 percent, preferably at least 10 percent (measured in accordance with the flexural or bending wave technique at 100 Hz). Due to the inventive combination of the elastic material layers, such as for instance wood, glass fiber reinforced plastic, aluminum or the like, which are known in ski construction, together with materials of high dampening values, it is possible to maintain the desired strength- and flexural or bending stiffness characteristics with high remaining elasticity. However, the ski nonetheless possesses an optimum dampening behavior during the start of fluttering or vibration of the ski tips or rear ends. These vibrations die out very quickly by virtue of the inventive insert- or support members.

It will be readily recognized that the dampening effect is that much better, that is to say, that the vibrations will tend to die out much more quickly, the more dampening material can be accommodated or housed in the ski and the less bridge formations occur between the non-dampening materials. Therefore, in accordance with the particularly advantageous embodiment of the invention layers of known material possessing an elastic pre-loading or pre-stress, such as for instance formed of glass fiber reinforced plastic, aluminum or the like, are completely encased by the dampening material.

The components which come into consideration for the inventive insert- or support members of a multi-layered ski are particularly the runner coating, the top coating, the side surfaces and the wedge insert.

Whereas originally the runner side of the skis were only provided with a thin wax coating, later with a lacquer or varnish coating, in order to improve the gliding properties of the skis, more recently there has been particularly employed a coating of the runner surfaces with polyethylene, which under certain conditions provides for exceptional sliding or gliding properties. However, the drawback of such a runner coating resides, on the one hand, in its low resistance to scratching, and, on the other hand, in its increasing the elastic properties, so that it works against the dampening of vibrations or oscillations. While indeed, high density polyethylene is readily used in order to improve the hardness, nonetheless when using same there still result deep scratches upon skiing over icy or even only slightly snow-bare locations. Additionally, through the use of high density polyethylene there results at low temperatures an additional embrittlement. Thus, especially when the skis are permitted to remain outside throughout the night it is quite possible that stresses can occur, which can lead to distortions, even if they are only slight, whereby, however, once again the exact guiding of the skis is impaired which, as previously explained, is today of special importance.

It is especially important according to the invention, that the side surfaces of the skis, which previously for instance, were formed of melamine resin or urea resin, are fabricated from a dampening material with the above described properties, in order to prevent the previously mentioned damaging bridge formation between the layers possessing strong elastic pre-loading and which generally guide above and below the core insert.

This core- or wedge insert previously was constructed of glued block wood, PVC, web constructions or the like. However, all of these inserts provided a relatively hard connection, do not provide for any great dampening effect, and, for instance as is the case especially with PVC, are too stiff at low temperatures. In this respect, the inventive ski with a core- or wedge insert formed of dampening material distinguishes itself particularly well and advantageously from the previously known constructions. In order to provide a saving in weight, the inserts are preferably constructed in profiled fashion, whereby it is particularly advantageous, to provide the recesses at the underside in order to afford sufficient support for the anchoring of screws which are necessary for the attachment of the binding from above.

Whereas wood exhibits a logarithmic decrement of the vibration reduction of 0.02 to 0.03 corresponding to 1 percent to 2 percent relative dampening, the polyester resins used for the coating of glass fibers possess a relative dampening of 2 percent to 4 percent, thermoplastic materials a relative dampening of 3 percent to 7 percent, and the web constructions coated with hard adjusted rubber qualities and already used in the fabrication of skis exhibit a relative dampening of 7 percent, the relative dampening of strongly filled rubber mixtures lie around 26 percent, of semi-hard polyurethane elastomers at 11 percent to 17 percent. Certain thermoplastic polyurethane types, even at low temperatures (for instance, minus 30° C.) nonetheless still achieve dampening values of 14 percent to 26 percent.

The mentioned materials which possess especially good dampening properties, however, partially do not exhibit as good sliding properties as for instance polyethylene. Thus, according to a further embodiment of the present invention, there is proposed a multi-layer ski, in which especially the dampening materials which are used at the runner surfaces and the side edges contain additives which improve their sliding or gliding characteristics, such as for instance, silicone, powdered graphite, molybdenum sulfide or the like. Certain rubber types can have their sliding properties improved with the aid of known surface acting fluorination techniques.

Such type runner coating can be manufactured, for instance, according to the following formulation:

linear saturated polyester with an average molecular weight 2000 460 pure diphenylmethane 4,4'-diisocyanate 225 powdered graphite-batch 40 monostyrene 150 polyethylene AC 75 silicone oil 7 1,4-butanediol 65 Total: 1,022

A good dampening for use in the construction of an inventive multi-layered ski in particular possess materials with high internal friction, for instance, heterogeneous cross-linked products, to which belong the previously mentioned polyurethane. Such products possess good dampening characteristics, especially at lower vibration frequencies, which is what one is here especially concerned about.

A further advantage of the inventive dampening materials which are employed, especially highly loaded or filled rubber qualities and elastomeric polyurethane, resides in the particularly high wear or abrasion resistance which far exceeds that of polyethylene, also high density polyethylene, without in comparable fashion leading at low temperatures to brittlement- or stress characteristics. Also, the scratch resistance and the puncture tear resistance of the inventive proposed materials is considerably higher than that of polyethylene. Whereas the latter, for instance, possesses a wear or abrasion resistance of 98 mg according to DIN-standard, only 50 mg were removed from a comparable polyurethane mixture under the same conditions.

Finally, it should still be mentioned that the particularly advantageous embodiment of the invention, according to which the entire ski -- with the exception of steel edges and at least one, preferably two to three elastic insert layers possessing pre-stress -- essentially consists of the dampening material. Such a ski is advantageously fabricated by directly molding around the inserts possessing the elastic pre-stress, which for instance, can consist of glass fiber reinforced plastic, or by direct vulcanization. In so doing, there do not appear any or only slight problems concerning the adhesion between the inserts and the dampening material which, if desired, can be reduced or overcome by the use of known adhesion promoters or bonding agents.

However, this technique can also be used for the case where there is only provided a single insert member or support formed of dampening material, which is connected with the remaining inserts by direct molding or vulcanization.

It should be readily understood that the inventive multi-layered ski can also be used as a water-ski, or for the fabrication of skibobs, or other glide runners.

In order to improve the sliding properties of a ski running surface formed of the inventive dampening material, there is further proposed to add to the material approximately 5 percent to about 50 percent, preferably about 10 percent to about 20 percent by weight, of a polyolefin. This polyolefin deposits itself in the elastomeric plastic material, sweats however during the processing temperatures, since it cannot be bound into the material and therefore forms a particularly good sliding surface upon the coating or covering.

Additionally, a completely surprising effect has appeared at the inventive dampening material which up to now cannot be theoretically explained. Whereas, for instance, a semi-rigid polyurethane elastomer, such as are used for soleing or shoes, possesses a wear or abrasion resistance of 40-45, the relatively hard polyethylene which has been previously used for the ski runner surface coating possesses a wear resistance of 98, and through the addition of 10 percent by weight of a low melting polyethylene to the same polyurethane elastomer, the wear resistance is reduced to 17.6. This is naturally of quite considerable importance for the strived for use.

Insofar as the production of the inventive dampening material proceeds on the basis of a polyurethane elastomer, then, according to a further feature of the invention it has been proposed that the polyolefin is added to the polyester or polyether required for the formation of the polyurethane, and the mixture heated to 120° C., whereupon the polyisocyanate required for the formation of the polyurethane is added while stirring, and that finally, the forming or imparting of shape be undertaken in known manner by casting or molding. Due to this procedure the addition or insertion of the polyolefin in the polyurethane is made easier and the distribution is improved.

Further objects will be apparent from the following description when considered in connection with the accompanying drawing, in which the single FIGURE is a cross section of the multi-layer ski with respect to the present invention.

The multi-layer ski consists of a runner coating 1, steel edges 2, an intermediate bonding layer 3, side surfaces 4, a top surface or coating 5 and a wedge insert 6. It is well understood that the invention is not limited to this example, but that more and different layers, inserts and the like may be provided, of which one or more are made of the inventive dampening material.

It should be apparent from the foregoing detailed description, that the objects set forth at the outset to the specification have been successfully achieved.