Cutters – for shaping – Rotary cutting tool – Including holder having seat for inserted tool
Reexamination Certificate
1999-10-27
2001-08-28
Wellington, A. L. (Department: 3722)
Cutters, for shaping
Rotary cutting tool
Including holder having seat for inserted tool
C407S049000, C407S046000, C407S052000
Reexamination Certificate
active
06280122
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to a metal-cutting milling tool.
Such tools are known that comprise a body rotatable around a central geometric axis, which body has a peripheral envelope surface extending between opposite end surfaces. In the envelope surface, recesses are provided which open outwards, each recess defined by a front wall, a rear wall and a bottom wall and has the purpose of receiving a machining element (e.g., a cassette which carries a cutting insert) as well as at least one clamping wedge arranged in the recess for fixing the machining element in place. The clamping wedge can be tightened by means of a clamping screw which enters a threaded hole formed in the bottom wall of the recess. The rear wall of the recess has first serrations arranged to co-operate with second serrations disposed on a rear side of the machining element, while the front wall is smooth in order to cooperate with a similar smooth front surface on the clamping wedge. A contact surface on the clamping wedge and a front contact surface on the machining element are both smooth in order to allow a substantially radial displacement of the clamping wedge in relation to the machining element during the clamping thereof.
PRIOR ART
A milling tool of the above generally mentioned kind is disclosed in SE 9103724-2 (corresponding to U.S. Pat. No. 5,395,186). In this case, the individual machining element, which is in the form of a cassette having a detachable cutting insert, is insertable in the appurtenant recess from either side of the body or cutter head in a direction generally parallel to the axis of rotation. The desired position of the cassette is achieved by a manual fine adjustment thereof before the clamping wedge is finally tightened. The possibility of applying a locator pin on the interior of the cassette intended to engage into a countersink in the bottom wall of the recess is discussed in the patent. However, this countersink has a larger diameter than the locator pin, so when the cassette is initially installed in the recess, the cassette does not attain a predetermined, exactly defined axial initial position.
The job of finely adjusting the cassette manually during the assembly of the tool is difficult and time-consuming. Another inconvenience of the design of the known tool is that it has only a limited ability to resist minor breakdowns of the type that easily may arise when the cassettes, together with the cutting inserts, are submitted to instantaneous impacts or shock loads. Therefore, even if total breakdowns can be avoided, frequently so much damage occurs to the cassettes that the cassettes have to be discarded and replaced.
Furthermore, each individual cutting insert is attached to the appurtenant cassette by means of a screw which incorporates a screw head, said screw extending through a through hole in the cutting insert and being fastened in a threaded hole in the cassette. Thus, the design not only includes a clamping wedge for fixing the cassette, but also a special clamping screw for fixing the cutting insert in the cassette. That means that, in practice, the tolerance chain between, on the one hand, the tool body together with the rotation axis thereof and, on the other hand, each one of the several cutting inserts, becomes extensive. This entails, among other things, that the precision in the adjustment of the cutting insert in relation to the tool body (which in practice should be less than {fraction (1/100)} mm) may easily be lost or become unsatisfactory, e.g. when the cutting inserts are replaced or indexed or when the cassette, for one reason or another, has to be dismounted and remounted.
OBJECTS AND FEATURES OF THE INVENTION
The present invention aims at obviating above-mentioned inconveniences of the previously known milling tool and at providing an improved milling tool. Therefore, a primary object of the invention is to provide a milling tool in which the machining elements, preferably in the form of cassettes having detachable cutting inserts, can be located in a simple way in an exactly defined operating position in relation to the tool body during the assembly of the tool. In other words, it should be possible to mount the machining elements rapidly without having to finely adjust them manually. Another object is to provide a milling tool with a good ability to resist at least minor incidents, which could cause breakdowns in connection with impacts or shock loads of an instantaneous character, which may occur. In particular, the machining element or should be able to resist such loads without being seriously damaged or displaced from its basic position. Another object of the invention is to provide a milling tool that is suitable for operation at very high rotational speeds, e.g. all the way up to the range of 20,000-30,000 revolutions/minute.
According to the invention, at least the primary object is attained by providing the tool body and each machining element with respective abutment surfaces which face generally axially and which abut one another when the machining element is installed, in order to define a precise initial axial positioning of the machining element.
REFERENCES:
patent: 3217384 (1965-11-01), Wirfelt
patent: 3378901 (1968-04-01), Dupuis
patent: 3675290 (1972-07-01), Mayer
patent: 4040156 (1977-08-01), Tack
patent: 5395186 (1995-03-01), Qvarth
patent: 5667343 (1997-09-01), Hessman et al.
patent: 5735649 (1998-04-01), Boscarino et al.
patent: 5800079 (1998-09-01), Qvarth
patent: 5967705 (1999-10-01), Wermeister
Burns Doane Swecker & Mathis L.L.P.
Ergenbright Erica
Sandvik Aktiebolag
Wellington A. L.
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