Abrading – Machine – Rotary tool
Reexamination Certificate
1999-11-24
2001-02-27
Scherbel, David A. (Department: 3723)
Abrading
Machine
Rotary tool
C451S114000, C451S177000, C451S209000, C451S229000, C451S253000, C279S004080, C279S051000
Reexamination Certificate
active
06193591
ABSTRACT:
FIELD OF THE INVENTION
This invention relates generally to grinding machines and more particularly to a system and collet assembly for loading, holding, turning and ejecting a workpiece.
BACKGROUND OF THE INVENTION
In grinding cylindrical workpieces, such as rollers, it is desirable to make consistent end products from the rough workpieces as efficiently as possible. Aside from the actual grinding time, improvements are needed to minimize the time necessary to load, clasp, rotate, move and eject the workpieces. Although in some cases the process has been automated, it is still desirable to improve machining efficiency and cycle time. One area in which time and efficiency are lost is in engaging and disengaging the workpiece by the grinding machine. In particular, many grinding machines use a collet or cylindrical, slotted clamp to engage one end of the workpiece, whereafter the collet is rotated to rotate the workpiece. Engineering difficulties have been encountered in configuring the collet to engage the workpiece quickly, allowing the collet to rotate, and disengaging the collet from the workpiece.
One response to this challenge has been to mount an outwardly biased collet within a cylindrical sleeve which is clamped in place, such as described in U.S. Pat. Nos. 5,443,411 and 5,556,326, both to Rouyer et al. and incorporated herein in their entirety. The collet is both rotated and extended to allow it to expand and then retracted with a rotation and translation motion to close and lock it relative to the sleeve. Specifically, the collet receives the end of the workpiece when the collet is in the extended open position. The collet is then turned and retracted into clamped sleeve, closing the collet untiocollet firmly clasps the workpiece and abuts the sleeve. The clamp on the sleeve is then released and the sleeve and collet are jointly rotated to turn the workpiece for grinding. After grinding, the sleeve is again clamped and the collet turned and extended to release the workpiece. This approach requires an excessive number of working parts and steps, and adds complexity, wear and tear, and processing time to the system.
Consequently, there is a need for an improved method of loading, clamping, and releasing a workpiece for grinding. The present invention addresses these needs.
SUMMARY OF THE INVENTION
The present invention relates to an assembly for holding a cylindrical workpiece for grinding. Normally the workpiece has a proximal end and a distal end. The assembly is based on a support frame having at least one support arm extending to initially hold the workpiece and operable to disengage from the workpiece during grinding. A tailstock is slidably mounted on the support frame and operable to engage the proximal end of the workpiece.
In one preferred embodiment, a collet assembly is mounted on the support frame and configured to receive and engage the distal end of the workpiece. The collet assembly includes a housing having an open proximal end, an open distal end, and an internal channel. The internal channel extends the length of the housing from the open proximal end to the open distal end. A spindle is slidably disposed within the internal channel of the housing. The spindle has a proximal end portion and a distal end portion wherein the proximal end portion includes a holding portion and wherein the distal end extends from the distal end of the housing and is engagable with a drive mechanism.
A collet is slidably disposed within the proximal end portion of the housing, wherein the collet has a proximal end adjacent the proximal end portion of the housing. The distal end of the collet is engaged by the holding portion of the spindle. The collet is resiliently biased so that the collet opens when advanced in the proximal direction, and so that the proximal portion of the housing urges the collet to close when the collet is retracted in the distal direction.
The assembly includes means engagable with the spindle for selectively advancing the spindle within the housing to advance the collet. A spring is disposed between the housing and the spindle and biased to resiliently urge said spindle in the distal direction.
It is one object of the invention to provide an improved collet assembly and system for loading, clamping, rotate and ejecting a workpiece.
Further objects, features and advantages of the present invention shall become apparent from the detailed drawings and descriptions provided herein.
REFERENCES:
patent: 5312212 (1994-05-01), Naumec
patent: 5375458 (1994-12-01), Oliver et al.
patent: 5806859 (1998-09-01), Saccomanno, III
patent: 5947485 (1999-09-01), Nguyen
Rookey Stephen Joseph
Stahl Joseph John
Sutton David Arden
McDonald Shantese
Scherbel David A.
Ten Cate Enbi International bv
Woodard Emhardt Naughton Moriarty & McNett
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