Chucks or sockets – Separate chuck-actuating power source
Reexamination Certificate
2000-11-21
2003-10-07
Howell, Daniel W. (Department: 3722)
Chucks or sockets
Separate chuck-actuating power source
C279S110000
Reexamination Certificate
active
06629697
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a chuck apparatus which is employed in a working machine such as a spinning machine and which holds a workpiece or a working tool.
2. Discussion of Related Art
There is known a chuck which is attached to a spindle or a main shaft of, e.g., a working lathe or an external cylindrical grinding machine to hold a workpiece, or a main shaft of, e.g., a milling machine or a drilling machine to hold a working tool. Though there are known various sorts of chucks, two sorts of chucks are particularly known in the art, i.e., (a) a three-jaw chuck which includes a main member and three holding jaws which are movable in respective radial directions of the main member, and (b) a collet chuck which includes a collet having a generally tubular shape, having a plurality of expanding slots extending in an axial direction thereof, and having one of an outer tapered surface and an inner tapered surface and additionally includes a main member having one of an inner tapered surface and an outer tapered surface that corresponds to the one tapered surface of the collet.
A conventional chuck apparatus includes, in addition to a chuck, a state switching device which selectively switches the chuck to a work-hold state in which the chuck holds a work and a work-release state in which the chuck releases the work. As the state switching device, there are known a manually operable one and a power-driven one. In the case where the chuck is not a rotary one, the state switching device used with the chuck may be of a more or less large size. However, in the case where the chuck is a rotary one that is attached to a main shaft and is rotated with the main shaft, there is a strong need to reduce the size of the chuck apparatus. In particular, the power-driven state-switching device is likely to have a large size, which results in various sorts of disadvantages. For example, if the chuck apparatus which is rotated with the main shaft has a large size, then the apparatus has a great moment of inertia, which makes it difficult to start and stop quickly the rotation of the main shaft and thereby makes it difficult to improve the working efficiency of the working machine. In addition, it is difficult for the working machine to secure a space sufficient to accommodate the large-size chuck apparatus. This problem becomes more serious in the case where a working machine as a whole is of a considerably small size or a single working machine employs a plurality of spindles or main shafts each of which is associated with a chuck apparatus.
Meanwhile, in the case where the state switching device is a power-driven one, it has been conventional that the power-driven state-switching device employs, as a power source thereof, a hydraulically-operated cylinder device. However, the hydraulic cylinder device has a problem that the operation of the cylinder device cannot be finely controlled, in particular, the operation stroke thereof cannot be accurately controlled. In addition, the working machine which employs the chuck apparatus needs to employ a stand which produces a hydraulic pressure. Thus, the size and cost of the working machine are increased. Moreover, since the hydraulic-pressure stand needs to be continuously operated during the operation of the working machine, the energy efficiency of the machine is decreased.
SUMMARY OF THE INVENTION
The present invention provides a chuck apparatus and a working machine which have one or more of the following technical features that are described below in respective paragraphs given parenthesized sequential numbers (1) to (18). Any technical feature that includes another technical feature shall do so by referring, at the beginning, to the parenthesized sequential number given to the latter feature. However, the following technical features and the appropriate combinations thereof are just examples to which the scope of the present invention is by no means limited. In addition, in the case where one technical feature recites a plurality of items, it is not essentially required that all of those items be simultaneously employed. That is, it is possible to select and employ only a portion (one, two, . . . , but not all) of those items.
(1) According to a first feature of the present invention, there is provided a chuck apparatus comprising a chuck; and a power-driven device which selectively places the chuck in an object-hold state thereof in which the chuck holds an object, and an object-release state thereof in which the chuck releases the object, the power-driven device comprising, as a power source thereof, an electric motor.
Since the power-driven device which selectively places the chuck in the object-hold state and the object-release state includes, as the power source, the electric motor, the present chuck apparatus is free of the above-identified problems and/or disadvantages of the conventional chuck apparatus in which the power-driven device includes, as the power source, the hydraulic cylinder device.
(2) According to a second feature of the present invention that includes the first feature (1), the electric motor comprises a servomotor.
Since the servomotor as the electric motor can be accurately controlled with respect to its rotation angle, torque, rotation speed, etc, an operation amount, and an operation force, of the chuck apparatus can be finely controlled.
(3) According to a third feature of the present invention that includes the first or second feature (1) or (2), the chuck comprises at least one holding member at least a portion of which is moved in a radial direction thereof so as to be selectively placed in the object-hold state and the object-release state, the power-driven device further comprises an axial-direction movable member which is movable in an axial direction of the chuck; and a first motion converting device which converts the axial-direction motion of the movable member into the radial-direction motion of at least the portion of the holding member, and the electric motor causes the axial-direction motion of the movable member.
(4) According to a fourth feature of the present invention that includes the third feature (3), the axial-direction movable member comprises a draw bar which transmits a tensile force to the chuck and thereby places the chuck in the object-hold state.
Since the chuck apparatus employs the draw bar, it is made possible to attach the chuck to a front end of a rotary shaft, such as a spindle, and provide the power source of the power-driven device around a rear end of the rotary shaft. Thus, it is made easier to dispose the power-driven device as a whole or the power source thereof. Since a tool rest or a work rest which is moved while holding a tool or a work is provided around the chuck, it is difficult, in many cases, to dispose the power-driven device around the chuck. However, the present chuck apparatus is free of that problem.
(5) According to a fifth feature of the present invention that includes the third or fourth feature (3) or (4), the power-driven device further comprises a first rotary member which is rotatable about an axis line of the axial-direction movable member and whose axial-direction movement is restricted; and a second motion converting device which converts the rotary motion of the first rotary member into the axial-direction motion of the movable member, and the electric motor rotates the first rotary member.
In the present chuck apparatus, since the rotation of the first rotary member causes the axial-direction movement of the axial-direction movable member, the rotary-type electric motor can be easily employed as the power source of the power-driven device.
(6) According to a sixth feature of the present invention that includes the fifth feature (5), the second motion converting device comprises a first threaded member which is substantially integral with the axial-direction movable member and a second threaded member which is threadedly engaged with the first threaded member, and the second threaded member is su
Amano Kazuo
Asai Koichi
Shioya Yasumoto
Teshi Nobuyuki
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