Dentistry – Apparatus – Tool bit
Patent
1983-04-19
1986-02-18
Whitehead, Harold D.
Dentistry
Apparatus
Tool bit
A61C 306
Patent
active
045711844
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
It is previously known to provide metal surfaces with a hard surface layer of another metal applied with the aid of an electric arc. Steel surfaces provided with surface layers of tungsten applied in this manner have for example been used in connection with rollers and die cutting tools. The surface layers, after surface treatment such as grinding and/or polishing, by virtue of their hardness or wear strength, are employed as the wear surfaces on the rollers and the cutting edges on the dies.
SUMMARY OF THE INVENTION
The present invention is based on the observation, made in connection with the known practice of applying a surface layer of another metal to metal surfaces by means of an electric arc, that such surface layers are, if the usual grinding and/or polishing thereof is omitted, not only surprisingly usable but even quite suitable as abrasive means. This has especially proved true in the field of dentistry, since tests with surface layers of this type have shown them to have very little effect on the relatively hard tooth enamel but are quite abrasive on such dental materials as gold, amalgam and the tooth's own bone substance (dentin). In other words, they are especially suited to smoothing tooth fillings of various types where the tooth enamel is to be left intact but the foreign material is to be evened out to make as smooth a transition as possible to the surrounding tooth enamel.
More specifically, implements for abrasion made according to the invention have proved to fulfill a previously unmet need within the field of dentistry. They have almost completely complemented the previously available implements of rubber and plastic used together with abrasive paste, and the implements of steel which are provided with diamond coatings. The rubber and plastic implements used together with abrasive paste are less rigid and wear-resistant and in many cases have insufficient abrasion but provide a very smooth surface, and the diamond-coated steel implements are many times much too abrasive leaving a rough surface. The implements made according to the invention with surface coatings or another metal applied with the aid of an electric arc, in addition to holding their shape and having a long life, also have an abrasive capacity lying between the two previously-mentioned types of implements, i.e. a comparatively good cutting capacity while providing a high surface finish on the tooth surface.
Even in comparison with steel implements such as ordinary files, the implements made according to the invention with surface layers of another metal applied by means of an electric arc have proved to be superior both as regards cutting capacity and life as well as high surface finish on the tooth surfaces.
Even if the stated examples of advantages with the implements made according to the invention for abrasion have been taken from the field of dentistry, the invention is not of course limited to this field but is generally applicable to other fields using abrasion, for example precious metals, metal alloys of various types, hardwoods, bone etc.
As has been stated above, an implement made according to the invention for abrasion and comprising a metal portion, provided at least partially with an abrasive coating, is characterized primarily in that the abrasive coating consists of a hard surface layer of another metal material than that of the metal portion, applied to the metal portion with the aid of an electric arc. Using steel for the metal portion serving as a carrier of the abrasive coating, tungsten has proved to be an especially suitable material for the abrasive coating. For the actual coating process, commercially available equipment can be used. No subsequent working of the surface of the finished abrasive coating is required. On the contrary, it is to be left as it is when applied with the arc.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention will be described in the following with reference to an example shown in the accompanying drawing of a suitable embodiment of an impl
REFERENCES:
patent: 1791968 (1931-02-01), Morgan
patent: 2645471 (1953-07-01), King
patent: 3496973 (1970-02-01), Ballard
patent: 3553905 (1971-01-01), Lemelson
patent: 4353696 (1982-10-01), Bridges
AB Dentatus
Whitehead Harold D.
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