Chucks or sockets – With fluid-pressure actuator – Socket type
Reexamination Certificate
2001-01-03
2002-12-24
Bishop, Steven C. (Department: 3722)
Chucks or sockets
With fluid-pressure actuator
Socket type
C279S004090, C279S050000, C279S051000
Reexamination Certificate
active
06497417
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to a collet chuck, more particularly to a collet chuck provided with a movable member which can be driven hydraulically in two opposite directions for operating a collet.
2. Description of the Related Art
Referring to
FIGS. 1 and 2
, a conventional collet chuck is shown to include a tubular body
11
, a rotating shaft
14
journalled in the tubular body
11
and provided with a frustoconical recess
162
, and a collet
12
disposed operably within the frustoconical recess
162
in the rotating shaft
14
for holding a rod-shaped workpiece (A) therewithin.
As illustrated, the tubular body
11
includes a hollow main body with open front and rear ends. A tubular shaft seat
13
is confined within the tubular body
11
, and defines front and rear bearing-retention recesses
131
at opposite ends thereof. Two ball bearings
18
are disposed in the bearing-retention recesses
131
in the shaft seat
13
to permit rotation of the rotating shaft
14
within the shaft seat
13
. A front cover
121
is disposed fixedly on the front end of the tubular body
11
to prevent removal of the rotating shaft
14
from the tubular body
11
. A rear cover
17
is disposed fixedly on the open rear end of the tubular body
11
, and has a plurality of bolt holes. The fastener bolts
172
extends respectively through the bolt holes in the rear cover
17
to engage threaded holes in the rotating shaft
14
, thereby preventing removal of the rotating shaft
14
from the tubular body
11
. A belt pulley
173
is sleeved fixedly on the rear cover
17
. The rotating shaft
14
consists of an inner sleeve
16
in which the frustoconical recess
162
is formed, and an outer sleeve
141
sleeved fixedly on the inner sleeve
16
so as to define an accommodating chamber
142
therebetween at a rear end thereof. The front cover
121
has an inner surface which is formed with a driving shoulder (
121
S) that abuts against a driven shoulder (
12
S) of the collet
12
. A tubular movable member
15
is mounted axially, movably and sealingly within the accommodating chamber
142
in the outer sleeve
141
and is further fastened securely to the inner sleeve
16
. A plurality of spring-retention elements
174
position a compression spring unit
175
between the rear cover
17
and the rotating shaft
14
in such a manner that the spring unit
175
biases the movable member
15
in a forward direction such that the inner sleeve
16
moves synchronously with the movable member
15
. Under this condition, when the rod-shaped workpiece (A) is inserted into the collet
12
, and when the front cover
121
is tightened, the workpiece (A) will be compressed radially by the collet
12
due to relative sliding movement between inclined surfaces
162
′,
123
of the inner sleeve
16
and the collet
12
, as best shown in FIG.
1
.
The tubular body
11
further has an oil chamber
153
that is located immediately in front of the movable member
15
. Two oil passages
143
,
132
are in fluid communication with the oil chamber
153
. When it is desired to release the workpiece (A) from the collet
12
, hydraulic oil can be fed to the oil chamber
153
via the oil passages
143
,
132
, thereby compressing the spring unit
175
within the tubular body
11
and consequently moving the movable member
15
and the inner sleeve
16
in a forward direction away from the frustoconical recess
162
, as shown by the horizontal arrows in
FIG. 2
, so as to release the workpiece (A) from the collet
12
.
Some disadvantages that result from the use of the aforesaid conventional collet chuck are as follows:
The clamping force of the collet
12
depends entirely on the spring unit
175
and cannot be adjusted. In addition, the spring
175
suffers from spring fatigue after long term use, thereby resulting in an eventual poor clamping effect of the collet
12
.
SUMMARY OF THE INVENTION
Therefore, the object of this invention is to provide a collet chuck having a movable member which can be driven hydraulically in two opposite directions for operating a collet, thereby enabling the collet to provide an effective clamping force on a workpiece.
Accordingly, a collet chuck of the present invention includes a tubular body, a rotating shaft assembly, a belt pulley, a collet, and a movable member. The tubular body has a front end and a rear end. The rotating shaft assembly is journalled within the tubular body, and has a frustoconical recess. The belt pulley is sleeved fixedly on the rotating shaft assembly. The collet is disposed operably within the frustoconical recess in the rotating shaft assembly, and is adapted to hold a rod-shaped workpiece therewithin. The movable member is mounted axially and movably within the tubular body in such a manner so as to be movable in a selected one of a tightening direction and a loosening direction. A front oil chamber is formed in the tubular body, and is located immediately in front of the movable member. A rear oil chamber is formed in the tubular body, and is located immediately behind the movable member. A first oil passage is formed in the tubular body, and is in fluid communication with the front oil chamber so that hydraulic oil can be fed to the front oil chamber therethrough, thereby moving the movable member rearward within the tubular body. A second oil passage is formed in the tubular body, and is in fluid communication with the rear oil chamber so that hydraulic oil can be fed to the rear oil chamber therethrough, thereby moving the movable member forward within the tubular body. Movement of the movable member in the tightening direction results in further movement of the collet into the frustoconical recess in the rotating shaft assembly for compressing the collet. Movement of the movable member in the loosening direction results in movement of the collet away from the frustoconical recess in the rotating shaft assembly so as to be adapted to release the workpiece from the collet.
REFERENCES:
patent: 2372592 (1945-03-01), Lovely
patent: 2387511 (1945-10-01), Henry et al.
patent: 2418082 (1947-03-01), Marasko
patent: 3073612 (1963-01-01), Birdsall
patent: 4690415 (1987-09-01), Holdridge
patent: 6173971 (2001-01-01), Shen
Bishop Steven C.
Pillsbury & Winthrop LLP
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