Cutters – for shaping – Rotary cutting tool – Including holder having seat for inserted tool
Reexamination Certificate
2000-09-05
2002-07-02
Tsai, Henry (Department: 3722)
Cutters, for shaping
Rotary cutting tool
Including holder having seat for inserted tool
C407S047000, C407S051000, C407S056000
Reexamination Certificate
active
06413021
ABSTRACT:
FIELD OF THE INVENTION
The invention relates to a rotating cutting tool, particularly to a rotating cutting tool adapted to high speed machining.
BACKGROUND OF THE INVENTION
The invention relates to a rotating cutting tool for high-speed machining, having at least one cutting insert interchangeably mounted to a main body of the tool or to a tool cassette, with at least parts of, respectively, the supporting surface of the cutting insert and of the receiving surface of the main body of the tool or tool cassette, when viewed in cross section perpendicular to the axis of rotation (R), being of an approximately V-shaped configuration and engaging with each other.
Rotating cutting tools for high-speed machining, such as high-speed milling cutters or high-speed drills, operate at very high rotational speeds of up to 80,000 rpm and more. These high rotational speeds cause a great amount of centrifugal force to occur at the tool, subjecting the tool parts to the utmost levels of stress. Due to this great amount of centrifugal force, it no longer is possible, as is customary for tools used in conventional cutting, to connect an interchangeable cutting insert having a flat supporting surface to a main body of the tool or to a tool cassette only in a non-positive way by means of a clamped mounting or by means of screws, since the permissible level of stress on the mounting means will be exceeded. Consequently, tools for high-speed machining require, in addition to a non-positive connection between an interchangeable cutting insert and the main body of the tool, the creation of an interlocking connection in order to absorb the greater part of the centrifugal force by means of said interlocking connection and to decrease the level of stress on the mounting means.
Known interlocking connections are, for example, groove and tongue connections in which the supporting surface of the cutting insert features a rectangular tongue which is engaged with a corresponding groove of the receiving surface of the main body of the tool.
However, this type of construction leads to very high levels of stress on the main body of the tool, above all, in the base region of the groove due to the notch effect.
DE OS 35 33 125 describes another embodiment of an interlocking connection between an indexable insert and the main body of a tool. According to this publication, the supporting surface of the indexable insert and the receiving surface of the main body of the tool feature toothed regions in engagement with each other, the teeth of which extend parallel to the axis of rotation and which feature a certain amount of flank angle.
The disadvantage of this type of embodiment lies in the fact that a multitude of bearing contacts causes the presence of an overdefinition, through which an unequivocal positioning of the indexable insert in the main body of the tool fails to be guaranteed. Moreover, this toothed region is very small in relation to the magnitude of the indexable insert, which may lead to the breaking of individual teeth.
In addition, rotating tools for high-speed machining also are known in which the main body of the tool features a flat V-shaped groove engaged by the supporting surface of an indexable insert configured with a corresponding raised V shape. In this connection, the supporting surface of the indexable insert, the receiving surface of the main body of the tool and the radial bearing surface of the indexable insert on the main body of the tool are coordinated with each other, with play, in such a way that when the indexable insert is correctly positioned, its supporting surface is supported in a precise, snug fit by the receiving surface of the main body of the tool.
A disadvantage of this type of embodiment is that high levels of centrifugal force and cutting force may cause an indexable insert to tilt laterally in an uncontrolled way, during operation of the tool.
OBJECT OF THE INVENTION
The purpose of the present invention is to provide a rotating cutting tool for high-speed machining for which the cutting inserts feature an interlocking connection to the main body of the tool, having positional stability even under operating conditions without the occurrence of mechanical overstress at the cutting inserts, mounting elements or at parts of the main body of the tool.
SUMMARY OF THE INVENTION
The invention pertains to a cutting tool for high-speed machining, having at least one cutting insert interchangeably mounted to a main body of the tool. At least parts of, respectively, the supporting surface of the cutting insert and of the receiving surface of the main body of the tool, when viewed in cross section perpendicular to the axis of rotation, are of an approximately V-shaped configuration and are engaged with each other. The crown region and also at least one of the end regions of the V-shaped supporting surface and receiving surface are mutually relieved. A bearing surface on the main body of the tool, in order to radially support the cutting insert, is arranged in such a way that a mounted cutting insert is tilted such that the supporting surface of the main body and the receiving surface come into mutual contact at only two points.
REFERENCES:
patent: 4462725 (1984-07-01), Satran et al.
patent: 4738570 (1988-04-01), Wertheimer
patent: 5054967 (1991-10-01), Noguchi et al.
patent: 5076739 (1991-12-01), Pano
patent: 5743680 (1998-04-01), Von Hass et al.
patent: 0469672 (1992-06-01), None
Ertl Christian
Koch Wolfgang
Morgan & Finnegan L.L.P.
Plansee Tizit Aktiengesellschaft
Tsai Henry
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