US3497202A

US3497202A - Mechanical leveling chuck

Info

Publication number: US3497202A
Application number: US594809A
Authority: US
Inventors: George E Bonin
Original assignee: Corning Glass Works
Current assignee: Corning Glass Works
Priority date: 1966-11-16
Filing date: 1966-11-16
Publication date: 1970-02-24
Anticipated expiration: 1987-02-24

Description

Feb. 24, 1970 G. E. scum MECHANICAL LEvELim cnucx 2 Sheets-Sheet 1 Filed Nov. 16, 1966 INVENTOR. GEORGE E. BONIN ATTORNEY Feb, 24, 1970 G. E.'BONIN MECHANICAL LEVELI NG CHUCK 2 Shets-Sheet 2 Filed Nov. 16, 1966 INVENTOR. GEORGE E. BONIN BY Y ATTORNEY United States Patent US. Cl. 269-47 3 Claims ABSTRACT OF THE DISCLOSURE A leveling chuck for retaining Ware articles to be finished with substantial supporting area contact by means of a plurality of upright support members each having a leveling arm pivotally connected thereto with flexibly mounted area-contact support pads on each end of said leveling arms The recent need for precision finishing ware articles, and particularly the bottom surface of culinary ware with improved flatness tolerances, has presented problems with regard to providing adequate means for suitably retaining or holding the ware to be finished. Since precision flatness is required to obtain optimum heat transfer between modern cooking surfaces and bottom surfaces of culinary ware, it is necessary that the holding means not only initially level the uneven inside or backing surface to its best average plane so as to facilitate the finishing of the outside surface to a predetermined thickness within acceptable tolerances, but also the holding means must adequately support the surface to be finished so as to maintain it in a substantially level plane and prevent flexing thereof, while compensating for irregularities which may appear on the internal or backing surface In the past, a vacuum chuck arrangement has been utilized in an endeavor to retain ware articles while the finishing operation is performed, by applying a vacuum across the back of the surface to be finished. However it has been found that the vacuum has a tendency to flex or to distort the unsupported surface being finished, with the result that when the vacuum is released, the finished surface distorts providing an unacceptable ware article In addition ware articles have been potted with plaster, pitch, wax, etc, to a pitching block or holder in order to adequately retain them for precision finishing. However, the time and expense involved in potting each ware article with its own individual pitching block does not lend itself to production line operations.

The present invention overcomes the problems heretofore encountered in chucking ware items for precision finishing, by providing a three-point leveling support having a large dispersed surface contact area with the ware, so as to avoid :point loading. Basically, my -improved chuck structure includes a plurality of flexibly mounted support pads pivotally connected to 3 upright members in such a manner so that the flexible pads firmly engage the inner or back side of a surface to be finished, while compensating for unevenness and irregularities in the supported surface, and providing a substantially level and solid three-point basic support therefore.

It thus has been an object of the present invention to provide an improved chuck structure for precision surface finishing, which overcomes the problems heretofore encountered with previously known devices.

A further object of the invention has been to provide an improved chucking device which firmly supports a ware article to be finished while compensating for unevenness and irregularities in the supported surface.

Patented Feb. 24, 1970 ICE An additional object of the invention has been to provide a tool for holding ware articles having an exterior surface to be finished wherein an uneven interior backup surface is leveled to its best average plane so as to facilitate the rapid finishing of the outside surface to a predetermined thickness within desired tolerances.

These and other objects of the invention will become more apparent to those skilled in the art from the following specification and accompanying drawings in which:

FIG. 1 is a top plan view of a novel chucking apparatus embodying my invention.

FIG. 2 is a side elevational view of the apparatus shown in FIG. 1.

Referring now to the drawings, my improved chuck apparatus 10 is shown having a circular base member 11 provided with a pair of opposed clamping flange assemblies 12 for retaining a workpiece 13 having a supported inner surface 14 and an outer surface to be finished 15. The base 11 is provided with 3 arcuately equally-spaced upright support members 16 which have a portion (not shown) extending downwardly into the base. The support members 16 are each vertically adjustable by means of a setscrew 17, which fixedly positions the portion extending Within the base 11.

Each upright support member 16 has a bifurcated upper end portion 18, pivotally retaining a leveling arm 29. A pivot pin 21 extends through a raised boss portion 20 formed on leveling arm 19 so as to provide the arm with stability through a low center of gravity. A commercially available flexible stud type leveling support pad 22 is adjustably mounted adjacent each end of leveling arm 19. The leveling pad 22 is preferably provided with a smooth-surfaced non-abrasive ware contacting material, such as nylon ring portions 23. Each support pad 22 has a downwardly extending stem or shaft 24 flexibly connected thereto by a ball and socket connection 24', which shaft is adjustably positioned within a vertical opening formed in arm 19, by means of a setscrew 25. A collar 26 is adjustably positioned on each shaft 24 by means of a setscrew 27, to regulate the amount or degree of flexing permitted by its associated leveling support pad 22.

In addition, an adjustable wedge member 28 is slidably positioned under the ends of each leveling arm 19, to limit the pivotal rocking movement of the arm. A tightening screw 29 fixedly positions each wedge member 28 in a desired location, so as to limit the pivotal movement of leveling arm 19 about pivot pin 21. As shown in FIG. 1, an auxiliary vacuum chuck 30, having a suction opening 31, may be provided centrally of the base 11, although such a device is not necessary to obtain operable results.

A plurality of retaining guide pins 32, having nonabrasive spool-like liners 33, may be positioned exteriorly of the workpiece 13 in order to guidably maintain the workpiece in position on the support pads. As shown, when the workpiece is provided with a pair of flanges 13a, the guide pins 32 may be positioned on opposed flange portions 34 of the clamping flange assemblies 12.

The flange portion 34 of each clamping flange assembly 12 is provided with a recessed portion 35 for pivotally receiving a bottom tongue portion 36 of a clamping device 37. The tongue 36 is pivotally retained in place by a bolt pivot means 38. The clamping device 37 has an upper jaw 39 pivotally connected to the bottom tongue portion by pivotal connecting means 40. An adjustable tightening screw 41 is provided to adjust the clamping pressure between upper jaw 39 and bottom tongue portion 36 of the clamping device 37. It has been found, however, that the clamping flange assemblies are not necessary to retain the workpiece in position upon the chuck apparatus when the apparatus is being rotated about its axial center, since the guide pins 32 suffice in maintaining the positionment of the workpiece. However, should the chuck apparatus be rotated eccentrically, the clamping flange assemblies provide added assurance that the work article will be maintained in its proper position.

Since the bottom surface of the base member 11 is accurately machined to a desired flatness, the support pads of the chuck assembly are easily adjusted and trued for positionment within a common plane by inverting the chuck apparatus upon a flat level surface. A level may then be placed upon the upwardly exposed bottom surface of the base 11, and the upright support members 16 appropriately adjusted by means of setscrews 17. Fine adjustment of the support pads 22 can be accomplished by positioning shafts or stems 24 by means of setscrews 25. Finally, the collars 26 may be adjusted by means of setscrews 27 to provide the flexible leveling support pads 22 with a desired degree of flexibility. Also, slidable wedge blocks 28 may be fixedly positioned under leveling arms 19 so as to limit the pivoting action thereof about pivot pin 21.

In operation, a workpiece or ware article 13 is placed in an inverted position upon the chuck apparatus 10. The inner surface 14 of the workpiece, which may be uneven due to manufacturing tolerances, is firmly supported by the flexible leveling pads 22 over a distributed surface area. The pads 22, being flexibly mounted on shafts 24, compensate for irregularities in the inner surface, and through pivotal leveling arms 19 and upright support members 16, support pads 22 level the supported surface to its best average plane for facilitating the finishing of outer surface 15. That is, upright support members 16 in effect provide a three-point suspension, which of course provides stability, but by itself would induce point loading under compressive finishing operations. However, leveling arms 19, provided with support pads 22 at their opposite ends, alleviate the problem of point loading, and in effect provide a distributed surface area support, while retaining the stability of a three-point suspension. Accordingly, with the present invention it is possible to not only obtain improved registry and leveling stability, but also substantially uniform grinding pressure distribution thus facilitating both ease and precision in providing a finished outer surface.

Although a now preferred embodiment of my invention has been set forth in great detail, it will be apparent to those skilled in the art that various changes and modifications may be made thereto without departing from the spirit and scope thereof.

I claim:

1. Leveling chuck apparatus for retaining a ware article with substantial supporting area contact for precision finishing including a base member and a plurality of substantially equally spaced apart upright support members operatively mounted on said base member, wherein the improvement comprises a leveling arm pivotally mounted on each said upright support member, support pad means on end portions of each said leveling arm including a leveling support pad for providing the ware with a substantially greater support area than that obtainable by said end portions, means flexibly mounting said leveling support pad on each said leveling arm to compensate for any unevenness in the supported surface and thereby provide substantial area contact with the ware, said means for flexibly mounting said support pad means including a vertically adjustable shaft for vertically adjusting said leveling support pad with respect to its associated leveling arm, means on said shaft for limiting the degree of flexibility imparted by said pad, opposed clamping flange assemblies operatively connected to said base member, and each of said flange assemblies being provided with a clamping device to securely clamp a workpiece in position on said leveling chuck.

2. Apparatus for supplying area support contact to a ware article to be finished and retain such article in a level attitude for precision finishing which comprises, a base member, a plurality of arcuately spaced-apart adjustable support members mounted on said base member, a leveling arm pivotally mounted intermediate its ends on each said support member, an adjustable shaft mounted on end portions of each said leveling arm, a leveling support pad carried by each said adjustable shaft for .providing a substantial area contact with the ware article, each said leveling support pad being flexibly mounted on said shaft to compensate for any local irregularity in the supporting surface and provide area contact therewith, means for limiting the degree of flexibility of said leveling support pads, and means for limiting the pivotal movement of each said leveling arm.

3. Apparatus as defined in claim 2 wherein said means for limiting the degree of flexibility of said leveling support pads includes collar means adjustably positioned on each said adjustable shaft intermediate its associated leveling arm and support pad, and said means for limiting the pivotal movement of each said leveling arm comprises adjustable wedge means slidably mounted on said base member and engageable with said leveling arms to limit the pivotal movement thereof.

References Cited UNITED STATES PATENTS 1,933,639 11/1933 Schafer 269267 X 2,379,244 6/ 1945 Miuton 269296 3,021,643 2/ 1962 Blanding.

ROBERT C. RIORDON, Primary Examiner L. GILDEN, Assistant Examiner US. Cl. X.R. 269296