Chucks or sockets – With fluid-pressure actuator – Socket type
Reexamination Certificate
1999-08-25
2001-05-01
Bishop, Steven C. (Department: 3722)
Chucks or sockets
With fluid-pressure actuator
Socket type
C279S043100, C279S050000, C279S043000
Reexamination Certificate
active
06224067
ABSTRACT:
The present invention generally relates to a chuck which is preferably intended to be used, with one end thereof, mounted in a rotary or non-rotary, machine tool, such as a drilling machine, a milling machine, a lathe machine etc., and whereby the opposite end of the chuck releasably holds a shaft tool, a work piece, a transition element or a similar object, like a drill, a milling tool, a rotary saw blade, a grinding roll etc. The chuck can be releasably mounted, or alternatively fixedly mounted in the machine tool. In the case of a releasably mounted chuck the chuck is mounted, for instance by means of a chuck cone part.
Several different embodiments of chucks of the above mentioned general type are known in the art. Such known chucks generally are formed so that the shaft tool is secured in the chuck by means of three or four radially movable clamp jaws which upon tightening are pressed into contact with the tool shaft. Clamp jaws provide a relatively little surface of contact with the tool shaft, and said jaws therefore have to be clamped with a relatively large force in order that the tool should not be capable of rotating in the chuck during machining. Therefore the jaws may damage the tool shaft, and after repeated mounting of the shaft tool the mounting accuracy of the tool can be reduced. The jaws also do not generally provide a prefect accuracy as to centering and balancing of the shaft tool, and it can be a heavy and relatively time consuming operation to clamp connect and to release the tool.
It is also known to mount shaft tools by means of heat clamp joints. It is, however, often difficult and time consuming to clamp connect the tool by such joints, and it is often also difficult to release the joint.
There are also chucks known in the art which are formed as hydraulic clamp bushings in the form of a double walled sleeve comprising a thin inner wall and an all around extending pressure gap which is filled with a hydraulic pressure medium which, upon pressurization, provides a radial compression and an expansion radially inwards of the thin inner wall, and thereby a clamp connecting of the tool shaft in the bushing. Such hydraulic clamp bushings are, however, rather expensive and may, for many purposes, be considered uneconomical.
The present invention relates to an alternative solution of the problem of providing a chuck for shaft tools, in which the chuck is cheaper and more simple as to its structure than the hydraulic clamp bushings, and which provides a better centering and balancing of the tool than conventional chucks having clamp jaws, and which also gives the same complete contact against the tool shaft as the hydraulic clamp bushings. The chuck according to the present invention also provides a very good clamping of the tool in the bushing.
The hydromechanical chuck according to the invention is a type of cone coupling chuck comprising a relatively thin inner sleeve arranged so that is can be radially compressed into contact with the tool shaft, and a solid outer sleeve which is axially displaceable on the inner sleeve, and in which the inner sleeve and the outer sleeve are formed with co-operating cone surfaces which, upon displacement of the outer sleeve on the inner sleeve, provides a radially inwardly directed compressing of the inner sleeve. The conicity preferably is such that the chuck is self locking. It is formed with a first press means for mounting and clamp connecting of the tool and a second press means for releasing the joint. To this end the chuck comprises hydraulic press means for displacing of the outer sleeve in both directions on the inner sleeve, namely a first hydraulic press means for providing such displacement of the outer sleeve on the inner sleeve such that said inner sleeve is compressed in the direction radially inwards into engagement with tool shaft, and a second hydraulic press means for forcing the outer sleeve in the opposite direction thereby providing a releasing of the joint.
The hydraulic press means comprises a first pressure chamber which can be actuated for clamp connecting a tool in chuck and a second pressure chamber for releasing the tool from the chuck.
In one embodiment of the invention the first pressure chamber is provided between the inner sleeve and the outer sleeve adjacent the outer end of the chuck and a second, corresponding pressure chamber is provided adjacent the inner end of the clamp sleeve of the chuck. The pressure chambers can be filled with a hydraulic pressure medium which can be pressurized.
The hydromechanical chuck according to this invention is useful for tools having a shaft of relatively course diameter, for instance a diameter of at least 10 mm. It may be difficult to handle tools of less diameters. In some cases it is possible to use reduction sleeves, but more conveniently the chuck is formed with an elongated tool mounting part having a reduced diameter. In the embodiment where the chuck has the elongated tool mounting part, both pressure chambers are arranged in a pressure head adjacent an inner end thereof. Also in this embodiment a first pressure chamber is adapter for clamp connecting the tool and a second pressure chamber is adapted for releasing the tool.
REFERENCES:
patent: 668286 (1901-02-01), Freese
patent: 2911222 (1959-11-01), Eve
patent: 3835649 (1974-09-01), Le Testu
patent: 3977065 (1976-08-01), Johnson
patent: 4580796 (1986-04-01), Baur et al.
patent: 5192086 (1993-03-01), Bucks
patent: 382517 (1964-11-01), None
patent: 1066211 (1967-04-01), None
patent: 86/01758 (1986-03-01), None
patent: 97/13604 (1997-04-01), None
Bishop Steven C.
ETP Transmission AB
Larson & Taylor PLC
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