Gear cutting – milling – or planing – Milling – Cutter spindle or spindle support
Reexamination Certificate
1999-12-08
2001-05-08
Briggs, William (Department: 3722)
Gear cutting, milling, or planing
Milling
Cutter spindle or spindle support
C279S131000, C408S23900A, C409S234000
Reexamination Certificate
active
06227778
ABSTRACT:
This invention pertains to the field of devices for machine tools that carry out machining operations by removing shavings such as drilling, reaming, grinding, etc. through the rotation of tool-carrying spindles.
More specifically, the sector to which the invention relates is that of sets that consists of a tool and a spindle, for which the clamping of the tool is accomplished by the action of the centrifugal force that acts on one or more parts that make up the sets themselves.
According to the state of the art, which corresponds to the description given in patent GB-A-944 283, a set of the type described above is produced by connecting a hollow cylindrical spindle to a tool, on whose tang one or more diametral cuts are made in such a way as to create two or more parts of the above-mentioned tang which, as the tool rotates under the action of centrifugal force, behave as brackets that are subjected to bending and expand radially, pushing against the cavity of the spindle and, by friction, clamping the tang itself and, consequently, the tool as well.
This approach, however, suffers from several limitations. First, since in the connection between the tang and the spindle there should be a very small amount of play, it is necessary to ensure very precise surface finishing of the parts that come into contact, to the detriment of the resulting coefficient of friction; this means that the kind of sets produced as described above turns out to be functional only at very high rotational speeds, and this limits their application.
Second, the machining of the various component parts is extremely delicate and very expensive.
Last but not least, it should also be considered that, in a set of the type described above, the tang, which deforms under the action of centrifugal force, “conicalizes” as it is deformed and consequently pushes against the cavity of the spindle virtually only at a set of points that form a circumference, unless appropriate conicalization in the opposite direction is provided for by means of expensive, fine grinding.
In order to avoid these drawbacks and limitations, the inventor of this invention has conceived of a set composed of a spindle and a tool which, with its shape, arrangement, and number of parts, makes it possible to obtain a clamping friction force that is approximately twice as high as those that can be achieved today at the same rotational speeds with tools of the same diameter.
The solution developed by the inventor also makes it possible to increase significantly the roughness that is acceptable in the parts that come into contact with one another under the action of centrifugal force and to produce the set that is the object of the invention by means of considerably less expensive machining operations.
The object of the invention is, in fact, a set composed of a spindle and a tool as described in the preamble to attached claim
1
, characterized as set forth in the characterizing part of said claim.
A preferred embodiment of a set according to the invention will now be described, but said embodiment should be considered neither limiting nor binding with respect to various other implementations that can be achieved based on the teaching contained in the attached claim.
REFERENCES:
patent: 3672256 (1972-06-01), Kosmowski
patent: 4006996 (1977-02-01), Kasabian
patent: 4979853 (1990-12-01), Field
patent: 5147165 (1992-09-01), Tempest
patent: 5603468 (1997-02-01), Stahlecker et al.
patent: 944 283 (1963-12-01), None
patent: 697260 (1979-11-01), None
Ballado Investments Inc.
Briggs William
Young & Thompson
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