Joints and connections – Interfitted members – Radially interposed shim or bushing
Patent
1992-11-18
1995-01-31
Nicholson, Eric K.
Joints and connections
Interfitted members
Radially interposed shim or bushing
403373, 403350, 403367, 192 41R, 192110R, F16D 4900
Patent
active
053854241
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a clamp device for rotary shaft portions.
BACKGROUND ART
The present invention relates to a device for clamping rotary shaft portions.
Hand brake devices, disk brake devices and like brake devices and clutch devices are well known as devices for clamping rotary shaft portions. Also known are clamp devices wherein a tapered sleeve is used for holding a shaft portion to a fixed portion (see, for example, Examined Japanese Utility Model Publication SHO 37-2711).
Such a clamp device is included in a tilting rotary table apparatus as shown in FIG. 6.
The tilting rotary table apparatus is attached to a machine tool for use in machining workpieces. The apparatus has a circular table rotating shaft 60 and a circular table tilting shaft 61. A circular table 62 is rotatable about the shaft 60 by a table rotating drive assembly 65 comprising a servomotor 63 for the rotating shaft, a worm 64, etc. The circular table 62 is further rotatable about the tilting shaft 61 by a table tilting drive assembly 70 comprising a servomotor 67 for the tilting shaft, a worm 68, a worm gear 69, etc.
The tilting shaft 61 or the rotating shaft 60 of the tilting rotary table apparatus is held against rotation conventionally by pressing a hydraulic pressure pad 73 against a brake plate 72 provided at one end of the tilting shaft 61 or by pressing a hydraulic pressure pad 74 against the periphery of the circular table 62.
When a great cutting force acts on the tilting shaft 61 of the table apparatus, exceeding the clamping force of the clamp device, the cutting force acts directly on the portions of the worm 68 and the worm gear 69 meshing with each other and is likely to damage the toothed face of the worm.
With the conventional clamp device, therefore, an increased hydraulic pressure is applied to provide a greater clamping force. However, the increased pressure, when applied to the hyraulic pressure pad 73, will cause marked wear on the tilting shaft brake plate 72 and a fixed portion 75 to shift the tilting shaft 61 axially thereof and displace the axis of the rotating shaft 60 of the circular table 62. Further if a great force is applied to press the pad 74 against the circular table, the rotating shaft 60 is likely to be warped by the force.
On the other hand, the clamp device, wherein a tapered sleeve is used, exterts a great fastening force and acts radially of the sleeve, and is accordingly less likely to cause damage to the toothed face of the worm and to displace the shaft axis. Nevertheless, the shaft portion of the tilting rotary table apparatus is frequently clamped and unclamped under remote control, so that extreme difficulties are encountered in using the tapered sleeve for the clamp device.
DISCLOSURE OF THE INVENTION
An object of the present invention is to provide a clamp device which is operable with extreme ease for clamping and unclamping a rotary shaft portion under remote control and which is capable of exerting a great clamping force and is unlikely to displace the shaft axis.
To fulfill the above object, the present invention provides the following means. More specifically, the present invention is characterized by a fixed sleeve radially elastically deformable, rotatably supporting a shaft portion and having a tapered surface over a periphery thereof on the opposite side of a shaft supporting portion thereof, a rotatable clamp member having a tapered surface fitting to the tapered surface of the fixed sleeve with rollers provided therebetween, the rollers being arranged as being inclined with respect to the axis of the sleeve, and a drive unit for rotating the clamp member.
According to the present invention, the rotatable clamp member is rotated in one direction by the drive unit. The rollers arranged on the tapered surface of the sleeve and inclined with respect to the axis thereof are each rotated about their own axis by the rotation of the clamp member to roll on the tapered surface in an oblique direction. Consequently, a screw action produced by the r
REFERENCES:
patent: 1834843 (1931-12-01), Humfrey
patent: 2068198 (1937-01-01), Seifarth
patent: 4278156 (1981-07-01), Yano
patent: 4593799 (1986-06-01), Ozaki
patent: 5109964 (1992-05-01), Fukui et al.
Knight Anthony
Nicholson Eric K.
Nikken Kosakusho Works Ltd.
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