Chuck assembly with a cooling mechanism

A chuck assembly includes a housing formed with a hydraulic fluid inlet, a sleeve mounted in the housing and formed with an annular groove, a shaft mounted rotatably in the sleeve and formed with a fluid passage, a chuck unit mounted in the shaft, a piston subdividing a chamber between the chuck unit and the shaft into first and second compartments, and a cooling mechanism having an air inlet formed in the housing, and an air channel formed in the sleeve and in fluid communication with the air inlet and the annular groove.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to a chuck assembly, more particularly to a chuck assembly with a cooling mechanism for cooling a hydraulic fluid in a clearance between a shaft and a sleeve of the chuck assembly.

2. Description of the Related Art

U.S. Pat. No. 6,497,417 discloses a conventional chuck assembly1that includes a housing10defining an inner space, a shaft11mounted co-axially and rotatably in the inner space and defining a chuck-receiving space13which has an enlarged end portion defining a piston-receiving chamber131, a sleeve12secured to the housing10and sleeved on the shaft11so as to define a clearance14therebetween, a bearing unit18disposed between the sleeve12and the shaft11, a chuck unit mounted in the chuck-receiving space13and including a plurality of jaws16for holding a workpiece (not shown), and a piston15mounted in the piston-receiving chamber131, displaceable in an axial direction, and connected to the jaws16in such a manner that axial displacement of the piston15results in radial displacement of the jaws16. The piston15subdivides the piston-receiving chamber131into first and second compartments1311,1312. A fluid channel17is formed in the chuck assembly1, is in fluid communication with the first compartment1311of the piston-receiving chamber131, and is adapted to be connected to a hydraulic fluid supply (not shown) so as to permit flow of pressurized hydraulic fluid into the first compartment1311, thereby resulting in axial displacement of the piston15.

Since the shaft11is operated at a relatively high speed, a relatively large amount of heat is generated due to friction between the shaft11and the sleeve12, which significantly increases the temperature of the hydraulic fluid in the clearance14, which, in turn, results in an adverse effect on the performance of the chuck assembly1.

The disclosure of U.S. Pat. No. 6,497,417 is incorporated herein by reference.

SUMMARY OF THE INVENTION

The object of the present invention is to provide a chuck assembly with a cooling mechanism that is capable of overcoming the aforesaid drawback of the prior art.

According to the present invention, a chuck assembly comprises: a housing that defines a cylindrical inner space therein and that is formed with a hydraulic fluid inlet adapted to be connected to a hydraulic fluid supply; a sleeve that is co-axially mounted in the inner space, that is secured to the housing, that defines a rotary-receiving space therein, and that is formed with an annular groove in fluid communication with the hydraulic fluid inlet; a rotary unit co-axially and rotatably extending through the rotary-receiving space, cooperating with the sleeve to define a clearance therebetween, and including a hollow shaft that defines a chuck-receiving space therein, that is rotatable relative to the sleeve about an axis, and that is formed with a fluid passage in fluid communication with the annular groove, the clearance being in fluid communication with the annular groove; a chuck unit that is co-axially mounted in the chuck-receiving space, that includes a plurality of angularly displaced jaws, and that cooperates with the shaft to define a piston-receiving chamber therebetween; a piston that is co-axially mounted in the piston-receiving chamber, that subdivides the piston-receiving chamber into first and second compartments, that is displaceable in an axial direction relative to the axis, and that is connected to the chuck unit in such a manner that axial displacement of the piston results in radial displacement of the jaws, the first compartment being in fluid communication with the fluid passage so as to permit entry of the hydraulic fluid therein, which, in turn, results in axial displacement of the piston; and a cooling mechanism having an air inlet that is formed in the housing and that is adapted to be connected to an air supply, and an air channel that is formed in the sleeve and that is in fluid communication with the air inlet and the annular groove so as to permit entry of an air flow into and through the clearance upon actuation of the air supply.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

For the sake of brevity, like elements are denoted by the same reference numerals throughout the disclosure.

FIGS. 2 to 5illustrate the first preferred embodiment of a chuck assembly according to this invention for holding a workpiece (not shown).

The chuck assembly includes: a housing100that defines a cylindrical inner space101therein and that is formed with a hydraulic fluid inlet102(seeFIG. 3) adapted to be connected to a hydraulic fluid supply (not shown); a sleeve20that is co-axially mounted in the inner space101, that is secured to the housing100, that defines a rotary-receiving space22therein, and that is formed with an annular groove23in fluid communication with the hydraulic fluid inlet102; a rotary unit30co-axially and rotatably extending through the rotary-receiving space22, cooperating with the sleeve20to define a clearance221therebetween, and including a hollow shaft31that defines a chuck-receiving space301therein, that is rotatable relative to the sleeve20about an axis, and that is formed with a first fluid passage312in fluid communication with the annular groove23, the clearance221being in fluid communication with the annular groove23; a chuck unit40that is co-axially mounted in the chuck-receiving space301, that includes left and right chuck bodies, and that cooperates with the shaft31to define a piston-receiving chamber311therebetween, each of the left and right chuck bodies having a plurality of angularly displaced jaws44; a piston33that is co-axially mounted in the piston-receiving chamber311, that subdivides the piston-receiving chamber311into first and second compartments3111,3112, that is displaceable in an axial direction relative to the axis, and that is connected to the chuck unit40in such a manner that axial displacement of the piston33results in radial displacement of the jaws44of each of the left and right chuck bodies, the first compartment3111being in fluid communication with the first fluid passage312so as to permit entry of the hydraulic fluid therein, which, in turn, results in axial displacement of the piston33; and a cooling mechanism having an air inlet61(seeFIG. 4) that is formed in the housing100and that is adapted to be connected to an air supply (not shown), and an air channel24that is formed in the sleeve20and that is in fluid communication with the air inlet61and the annular groove23so as to permit entry of an air flow into and through the clearance22upon actuation of the air supply after the supply of the hydraulic fluid is stopped, thereby cooling the hydraulic fluid trapped in the clearance22during rotation of the shaft31. A check valve62is installed in the air inlet61for permitting the air flow to flow therethrough in a forward direction from the air supply to the air inlet61and for preventing the air flow from returning in a reverse direction opposite to the forward direction.

An urging member34is mounted in the second compartment3112in the piston-receiving chamber311, and abuts against the piston33so as to accumulate a restoring force for restoring the piston33back to a normal position when the pressurized hydraulic fluid enters into the first compartment3111and moves the piston33to compress the urging member34.

The chuck unit40further includes left and right actuating members42,43that are respectively associated with the left and right chuck bodies, and a connecting member45that interconnects the left and right chuck bodies. The piston33is connected to the left actuating member42in such a manner that axial displacement of the piston33in a direction toward the urging member34(i.e., compresses the urging member34) during the release of the workpiece from the left and right chuck bodies results in movement of the left actuating member42together with the connecting member45away from the left chuck body, which, in turn, results in pushing of the left chuck body through the connecting member45and thus movement of the right chuck body away from the right actuating member43.

The rotary unit30further includes a bearing spacer ring35that is sleeved on the shaft31and that cooperates with the sleeve20to define the clearance22therebetween. The bearing spacer ring35is formed with a second fluid passage351that is in fluid communication with the first fluid passage312and the annular groove23, and cooperates with the shaft31and the sleeve20to define a pair of bearing-receiving spaces for receiving a pair of bearings36therein, respectively.

Referring toFIG. 3, the sleeve20is further formed with an oil channel25that is in fluid communication with the annular groove23in the sleeve20and the hydraulic fluid inlet102in the housing100.

Referring toFIG. 5, the housing100is further formed with an oil outlet70that is adapted to be connected to an oil collector (not shown). The sleeve20is formed with a second oil channel26that is in fluid communication with the oil outlet70in the housing100and the annular groove23in the sleeve20so as to collect the hydraulic fluid leaking from the clearance22.

Referring toFIGS. 3 to 5, a plurality of hydraulic fluid storing grooves222are formed in the sleeve20, and are in fluid communication with the clearance22for collecting the hydraulic fluid therein.

FIG. 6illustrates the second preferred embodiment of the chuck assembly according to this invention. The chuck assembly of this embodiment differs from the previous embodiment in that the chuck unit40includes a sole chuck body.

With the inclusion of the cooling mechanism in the chuck assembly of this invention, the aforesaid drawback as encountered in the prior art can be eliminated.

With the invention thus explained, it is apparent that various modifications and variations can be made without departing from the spirit of the present invention. It is therefore intended that the invention be limited only as recited in the appended claims.