BACKGROUND OF THE INVENTION-TECHNICAL FIELD A ski, for example a cross-country ski or a jumping ski, has (at the bottom of the ski) a base devised with the intention that it will give a good glide. A means to improve the sliding properties is to impress, cut, or grind a fine pattern of relief into the surface of the base. For this purpose there are various tools, and it is within this field that the invention lies.

BACKGROUND OF THE INVENTION-TECHNICAL PROBLEM SOLVED BY THE INVENTION It is well known that a suitable relief pattern (commonly known as a structure) in the ski base improves the glide of the ski particularly in warm snow conditions. Straight, 0.05-0. 2 mm deep, parallel grooves, separated by 0.3-2 mm, are ordinarily formed. The base of cross-country skis is in general about 45 mm wide, of which approximately 39 mm constitutes a flat surface and about 6 mm constitutes a groove with gradually increasing depth down to about 1 mm in the middle of the ski base. The relief pattern is applied on the flat part of the ski base. However our tests on cross-country skis indicates that the glide may be improved by also rilling the running groove of the ski. Patterning the ski's running groove appears not to be previously known, and as far as we know there is no known tool specifically devised for this purpose.

BACKGROUND OF THE INVENTION-PRIOR ART [Gmeiner] A tool for applying a relief pattern in the base of a ski is described in patent DE-19901199. The tool consists of a surface-grooved roller on a shaft, with a handle at each end of the shaft. The tool is intended for flat bases. The design patent DE-29905528 (by the same inventor) seems to describe a similar hand tool but with two surface-grooved rollers.

[Holmenkol] The product Holmenkol Tri-Maxx is also a tool for patterning flat bases. It is equipped with three, permanently

mounted, surface-grooved rollers and two handles.

[Toko] The product Toko Structurite is yet another hand tool for flat bases. The tool has room for a replaceable surface- grooved roller. A plastic cover on the roller facilitates pressing the roller against the base with one hand.

[Rolling] All of the above-mentioned tools have rollers that freely rotate (not slide) along the base of the ski. The pattern is created because the roller's elevations penetrate into (and redistributes material in) the base; base material is thus not consumed.

[Cutting] In contrast to the above-mentioned tools, there are also tools that, except for impressing, also cut grooves in the base. These are categorized in two types. The first (exemplified by SWIX T401) has permanently mounted, grooved blades. The second has a grooved roller with backspin rotation (this type is commonly known as"tractor"). Both these types are only intended for flat surfaces.

[Machines] All of the above-described devices are hand tools.

Larger devices for structuring skis are represented primarily by the commonly known grinding machines (example PCT/AT99/00009), but also laser devices have been reported (example DE-3935927). However not even in this field can we find any example that the ski's running groove is being structured, or that one has become aware of any advantage of doing this.

[Limited to flat bases] Skis with relief pattern in the base are well known since a long time ago. We have however not been able to find any example of someone having noticed the importance of patterning the running groove. We have examined a number of patents but have found that these only describe structuring of flat bases (examples given in the following paragraph).

[Skis] Described in patent US-5,727, 807 is a ski with a surface structure in the form of straight grooves, 0.02-0. 08 mm deep.

The ski is divided into zones (middle, edge, top, and tail zone) having different surface structures. The edge zone is for example prescribed to be wider than 0.03 times the ski's width.

Also in patent US-5,725, 237 the ski is divided into zones (front and sliding zone) having different surface structures.

The surface structure consists of straight grooves deeper than 0.015 mm in the sliding zone but shallower than 0.015 mm in the

top zone. Even if these two patents points to advantages of having different surface structures on different parts of the ski, there is no mentioning of the running groove or its surface structure. Patent DE-2623852 describes a ski with a surface structure consisting of straight longitudinal grooves, 0.1-1 mm deep. Patent FR-934.319 presents a ski with a surface structure in the form of straight longitudinal grooves (claimed to influence both kick and glide). The ski is divided into zones (top, middle, and tail zone), having different material and surface structure. The ski in patent CH-331559 is characterized by the depth of the grooves being less than 2 mm, and the grooves being placed so close to each other that the surface becomes undulated (in contrast to sharp grooves widely spaced apart). Patent US-5,328, 200 demonstrates a solution with longitudinally wavy grooves (with constant depth). In patent DE-4033235 the ski has a surface structure in the form of straight grooves, 0.05-0. 25 mm wide and 0.01-0. 1 mm deep. The grooves lie essentially in the ski's longitudinal direction and are only 3-20 mm long. Patent FR-1.102. 116 states the importance of the grooves being shallow enough to yield an undulating base surface (i. e. the grooves not being sharp).

Patent DE-1108599 shows the advantages of eliminating the running groove (on Alpine skis). The base has longitudinal grooves but not over the entire surface: a 1.5-3 cm wide surface region does not have grooves. Patent CH-161592 describes a ski with a surface structure in the form of straight longitudinal grooves. The grooves may be shallow with sharp edges. Patent US-3,378, 274 described a ski with straight longitudinal grooves (with unspecified measures), which is supposed to give a directionally stable ski. The ski in patent AT-961335 has longitudinal straight grooves, characterized in that they are not connected along the whole length of the ski (i. e. they are short).

[Conclusion] Both in the field of devices (for patterning ski bases) and in the field of skis (with patterned bases), it thus seems that patterning of the running groove of a ski is not known.

OBJECTS OF THE INVENTION The object for this invention is a device that can easily be integrated as part of different tools or machines for production of relief patterns in the base of a ski's running groove.

DRAWINGS-BRIEF DESCRIPTION Fig 1... The roller's main components.

Fig 2a... Embodiment with a fixedly connected shaft.

Fig 2b... Embodiment with a separate shaft.

Fig 3... Embodiment with small trundle diameter.

Fig 4... Embodiment with rolling bearing.

Fig 5... The trundle's relief pattern.

Fig 6... Example of patterned running grooves.

Fig 7a... The invention integrated with handle, example 1.

Fig 7b... The invention integrated with handle, example 2.

Fig 7c... The invention integrated with handle, example 3.

Fig 8... The invention as part of a"tractor tool".

Fig 8a... Front view of essential parts of tractor tool.

Fig 8b... Front view of essential parts of tractor tool (but without chassis).

Fig 8c... Side view of essential parts of tractor tool (but without chassis).

DRAWINGS-NAME OF PARTS 101... Running groove (curved base surface).

102... Sliding surface (flat base surface).

201... Ski base.

202... Ski core.

1... Trundle.

2... Shaft.

3... Chassis.

4... Bearing.

5... Handle.

11... Edge.

31... Rail groove on chassis (3).

51... Stop edge.

6... Tractor tool.

61... Friction roller.

62a... Cogwheel"a".

62b... Cogwheel"b".

62c... Cogwheel"c".

62d... Cogwheel"d".

62e... Cogwheel"e".

63a... Shaft"a".

63b... Shaft"b".

63c... Shaft"c".

64... Chassis (mounting for shafts"a", "b","c", and (2)).

DRAWINGS-MEASUREMENTS Bw... [Ski] Width of base.

Bt... [Ski] Thickness of base.

T... [Ski] Thickness of core.

Sw... [Ski] Width of running groove.

Sh... [Ski] Depth of running groove.

Hw... Width of trundle.

Hd... Diameter of trundle.

Aw... Length of shaft.

Ad... Diameter of shaft.

Mp... Fineness of pattern (distance between lines).

Mh... Relief height of pattern. r... The trundle's mantle curvature.

DETAILED DESCRIPTION OF THE INVENTION [Main features] The invention is now described in detail. In fig 1 the invention's two main components are shown: a patterned trundle (1) with a shaft (2). The entire device, i. e.

(1) and (2) together, is referred to with the word"roller".

The figure also shows a cut out cross section of a ski. An approximately 1 mm thick base (201) is attached to the ski core (202). The base has a nearly 20 mm wide flat surface (102) on each side of an approximately 6 mm wide and 1 mm deep depression (101). The purpose of the roller is to create a relief pattern in the surface (101).

[Two embodiments] The invention has two generic embodiments.

The trundle (1) and the shaft (2) may be fixedly joined as one unit as shown in fig 2a, or they may be movable with respect to each other as in fig 2b. The roller (trundle and shaft) is typically manufactured in metal such as brass or steel, but also other hard materials may be used. The width of the trundle (Hw) is usually about 6 mm, and its diameter (Hd) is typically around 20 mm, like in these two examples of embodiments. The shaft may be manufactured with a diameter (Ad) and length (Aw) of 10 mm respectively 80 mm. A thinner diameter shaft is also feasible with properly designed mounting for the shaft (more of this in the next paragraph).

[Small trundle diameter] Another embodiment is shown in fig 3.

The trundle's diameter is only 8 mm and the shaft diameter is 2 mm. The shaft is mounted in a chassis (3). The rail groove (31) is then attached to a handle (described in more detail

later).

[Rolling bearing] A rolling bearing (4) may be mounted between the trundle and the shaft (see fig 4). This embodiment is a variant of the one shown in fig 2b. Notice that (in both cases) the trundle rotates not only around the shaft but can also slide along the shaft. The benefit of this is explained in a subsequent paragraph.

[Mantle profile] We now proceed to describe how the mantle surface of the trundle transfers a pattern to the ski base. An enlargement showing (a cross section of) the mantle region of three trundles is given in fig 5. The mantle surface consists of (grooves and) ridges (11) with the height (Mh) and spaced a distance (Mp) apart. The ridges are located approximately along a circle with radius (r). The figures are drawn proportionally, where (r) equal to 8 mm may be taken as a reference. The three mantle surfaces represent the coarsest, a medium coarse, and the finest pattern, that could be envisioned practically useful.

[Pattern types] The relief patterns created in the ski base (see fig 6) would be mainly parallel straight lines (upper example) or short straight lines (the two lower examples). The invention is however not restricted to a specific pattern.

[Handles] The roller (trundle and shaft) may be integrated as a part in different tools. Typically different kinds of handles (5) are attached, and examples of this are given in fig 7. The purpose of the handles is to make it feasibly for a person to use his or her hands to press the trundle's mantle surface against the base while the trundle is rolled along the running groove. For the embodiment in fig 7a, the shaft is desirably screwed to, or fitted fixed with, the handle. And it is the trundle that rotates in addition to being free to slide along the shaft. The handle may for example be made of stable plastic. Also tools having two handles, as in fig 7b, may be devised so that the trundle rotates as well as is free to move along the shaft. Observe that the edge (51) has a purpose of restricting the axial movement of the trundle on the shaft. For the embodiment in fig 7c the roller's shaft is mounted to the chassis (3) via a bearing, and the chassis'rail groove (31) (refer back to fig 3) moves along a rail (not shown in the figure) that is screwed or molded, fixedly connected, to the handle.

[Tractor] Yet another example of how the invention may be integrated with other parts, to make a tool, is shown in fig 8 (corresponds to the flat base tool known as"tractor"). The 285 tool (6) is pressed against, and moved along, the ski. The friction roller (61) (rolls along the flat base surface (102) and) drives the shaft (2). The power transmission (between (61) and (2) ) takes place by means of the cogwheels (62a), (62b), (62c), (62d), and (62e). For transparency's sake, we point out 290 that the chassis (64) that constitute mounting means for the shafts, only is pictured in fig 8a (being a front view), and not in fig 8b (being a top view) or in fig 8c (being a side view). The tool is characterized by the fact that it can be used to cut or grind rills in the base. The trundle (1) (that 295 is fixedly connected to the shaft (2) ) will more or less cut or grind the base because it rotates opposite to (61). Thereby a more permanent pattern can be obtained compare to if the trundle only is pressed into the base. Dependent on the cogwheel gearing and the number of gears, the speed (and in 300 principle also the rotation direction) can be varied to optimise the handling, and cutting or grinding properties.

[Machine] The roller may also be a part of a machine driven by a motor. In this case the material of the trundle's mantle 305 surface could be of stone, ceramic material, Bakelite bonded boron nitride or diamond, or other material with good grinding properties.

[Variation of the running groove] A single shape of the 3io trundle's mantle surface fits skis from different makers, and fits even when the base has been scraped or grinded thinner.

Namely, a number of ski makers'skis (for example Atomic and Madshus) have the same shape of the running groove. This shape is approximately a segment of a circle with the diameter 8 mm.

315 There are however exceptions, and Peltonen has models that differs by having a larger circle diameter of about 12 mm, which means that those skis requires another form of the trundle's mantle surface. The segment's chord is 5-6 mm when the ski is new (valid for above-mentioned makers'skis) but 320 diminishes in proportion to the wear of the flat part of the base. Similarly for the depth of the running groove, and it is ordinarily 1-1.5 mm (and approximately 0.5-0. 8 mm for Peltonen) when the ski is new. The circle diameter is also not varying along the length of the running groove. A jumping ski has 325 several running grooves (normally 5 or 6 grooves). The shape of the grooves in general similar to that of cross-country skis (from Fisher, Atomic, and Madshus).