Dentistry – Apparatus – Tool bit
Reexamination Certificate
2000-01-18
2001-07-17
Lucchesi, Nicholas D. (Department: 3732)
Dentistry
Apparatus
Tool bit
Reexamination Certificate
active
06261096
ABSTRACT:
BACKGROUND
1. Field of the Invention
The present invention relates to an improved dental tool comprising a head and a shaft which can rotatably be supported in a drive device.
2. Related Art
In dental laboratories dental technicians are nowadays using, in particular, milling tools for machining the most different materials, said tools being preferably made from carbide. The surfaces, for example, of crowns, bridges, or the like, are machined with the help of said milling tools to subsequently finish and polish the surfaces with the help of high-precision grinding tools in an additional working step. The dental technician is here using different tools in successive order, which requires several tool-changing operations.
Hence, during machining, a dental technician has to provide different tools on the one hand, and the machining time is prolonged by several tool-changing operations on the other hand.
SUMMARY OF THE INVENTION
Therefore, it is the object of the present invention to provide a dental tool which can easily be handled and produced and is able to carry out different machining steps.
Said object is achieved by a dental tool comprising the features of claim
1
. Advantageous developments are the subject matter of the subclaims.
Hence, a dental tool according to the invention comprises a first, second and third toothing. Thanks to such a triple toothing the dental tool according to the invention, in particular a dental milling cutter, is suited for both roughing and smoothing, which will hereinafter be referred to as finishing in accordance with technical dental language. Thus the triple toothing creates a universal tool which avoids troublesome tool-changing operations. The machining time can thereby be reduced considerably. The three toothings can each be used for different working steps.
Depending on the respective material, a dental technician can also vary the cutting characteristics of the dental tool with the triple toothing by selecting different speeds. A high speed is preferably chosen for roughing operations whereas a low speed is chosen for finishing work. However, the respectively optimum speeds have to be determined in response to the material.
Preferably, the first toothing extends from a tip of the head towards an end of the head at the shaft side. Thus the first toothing extends over the entire length of the head and is used for the main removal work, i.e. for roughing operations.
Depending on the type of the material to be machined and the rotational direction of the tool, the first toothing is straight-toothed, or has a left-hand or right-hand helix or twist (the terms helix and twist shall be regarded as equivalent within the meaning of this invention). In the case of a toothing having a helix, the helix angle is preferably between 4° and 6°. Preferably, the dental tool can also be constructed in symmetry with a plane containing the central axis of the dental tool.
The second toothing is advantageously provided on the cutting edges of the first toothing. For example, the second toothing may be designed as a staggered toothing which comprises cutting edges extending in a direction transverse to the cutting edges of the first toothing. The second toothing can primarily be used for the fine-machining of a surface. Hence, it is preferably used for finishing work. Preferably, the second toothing is arranged at a helix angle of about 25° to 35°.
To improve the cutting capacity as well as the removing capacity, the second toothing advantageously comprises a plurality of cutting edges. Preferably, a plurality of cutting edges of the second toothing are provided on the first toothing. The removing capacity of the dental tool can further be increased thereby. Apart from an active cutting edge, the second toothing also comprises a smoothing cutting edge which is in particular used for finishing work, thereby creating a surface of reduced roughness.
In a preferred embodiment, the third toothing is designed as a transverse cut. In particular, the chip dimensions can thus be influenced in a positive manner such that the size of the separated chips is relatively small. As a result, the chips can be discharged in a simplified manner. Moreover, a transverse cut avoids undesired vibrations of the dental tool during machining.
Preferably, the transverse cut of the third toothing which is provided on the first toothing is differently designed on a cutting edge of the first toothing. As a consequence, the cutting edges of the first toothing are different from those of the third toothing.
Advantageously, the second toothing and the third toothing have opposite helices. Very small cutting segments can thereby be produced on the head of the dental tool, resulting in a diamond-like cutting-edge geometry. Thus the dental tool can inter alia be used in both rotational directions.
In a preferred embodiment, two toothings of the third toothing are respectively provided between two adjacent toothings of the second toothing. As a result, the chip production, in particular, can advantageously be influenced in the form of small chips, and undesired vibrations can also be avoided while the surface is being machined.
To create a toothing which has a cutting effect in both rotational directions of the tool, the third toothing is advantageously identical with the second toothing, with the two toothings having an opposite helix. This results in a diamond toothing having rhombic cutting segments, with a plurality of cutting edges of the two toothings being in respective engagement.
REFERENCES:
patent: 1358432 (1920-11-01), Fink
patent: 3832779 (1974-09-01), Reynaud
patent: 4284406 (1981-08-01), Hughes
patent: 198 10 284 A1 (1999-09-01), None
patent: 0 493 701 A2 (1992-07-01), None
Danger Karl-Heinz
Schon Jurgen
Gebruder Brasseler GmbH & Co. KG
Lucchesi Nicholas D.
Wolf Greenfield & Sacks P.C.
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