US1329733A - Magnetic chuck - Google Patents

Description

0. S. WALKER.

MAGNETIC CHUCK.

APPLICATION FILED MAR. 8. I919.

1,329,733. Patented Feb. 3,1920.

Mm 43 m UNITED STATES PATENT OFFICE.

OAKLEY S. WALKER, OF WORCESTER, MASSACHUSETTS, ASSIGN OR TO O. S. WALKER 0E WORCESTER, MASSACHUSETTS, A CORPORATION OF MASSACHUSETTS.

MAGNETIC CHUCK.

To all whom it may concern:

Be it known that I, OAKLEY S. WALKER, a citizen of the United States, residing at Worcester, in the county of Worcester and Commonwealth of Massachusetts, have invented a new and useful Improvement in Magnetic Chucks, of which the following, taken in connection with the accompanying drawings, is a specification.

The present invention relates to magnetic "chucks, and has particular reference to a novel and improved construction and arrangement of parts for a device of this class, whereby the same affords a finely divided work holding face which is peculiarly adapted for the retention of small pieces of work. The invention resides primarily in a new principle of construction and a novel inter-relation for the pole pieces of the chuck, which is fully set forth in the follow ing description and illustrated in the accompanying drawings, wherein Figure 1 is a partial top plan view of a chuck embodying my invention.

Fig. 2 is a vertical sectional view of said chuck, taken substantially in a diametrical plane.

Fig. 3 is a detached view of one of the polar sections of the face plate of the chuck.

Fig. 4 is a detached view showing two of such polar sections in cooperative position.

Fig.5 is a fragmentary sectional view on the line 5-5, Fig. 4, showing the manner in which one row of pole piece projections is insulated from the base of the adjacent pole iece. .f p Like reference characters refer to like parts in the different figures.

Referring to the drawings, the numeral '1 denotes the base or shell of the chuck, which is here shown as circular in form and adapted to be rotated, although obviously the principles of the invention as herein disclosed are equally applicable to a rectangular stationary chuck, or any other shape desired. The shell 1 provides a central aperture 2 for the attachment of a shaft or spindle, not' shown, by means of which the chuck may be rotated. The hollow interior of the shell 1 is adapted to receive and support'a plurality of separate core members 3, 3, which are here s own as radially arranged for'the circular type of ehuck illusti-ated, although obviously for a rectangular Specification of Letters Patent.

Patented Feb. 3, 1920.

Application filed March 8, 1919. Serial-No. 281,362.

chuck these core members would be arranged I longitudinally in a row. Each core member 3, which in horizontal section is substantially triangular, has an individual coil or windin 4, the coils of adjacent core members being oppositely wound or otherwise so arranged as to impart opposite magnetic polarity to adjacent cores. The coils 4 are suitably connected in any well known manner to the usual contact rings 5 and 6 which depend from the shell 1 and are suitably insulated therefrom, said rings rotating in contact with suitable brushes or the like, not shown, whereby to secure the passage of electric current through the coils 4 when the chuck is energized.

The face plate of the chuck is adapted to cover and inclose the shell 1, and is held in place by suitable screws or bolts 7, 7, which pass from the bottom of the shell up through the core members 3, 3, and into said face plate, which latter is thus detachable when desired to afford access to the interior of the chuck for purposes of inspection or repair. Said face plate consists of an annular rim 8 which rests on the upper edge of shell 1 and which incloses a circular space, which is adapted to be filled substantially by the several polar sections ofthe face plate, one of which is shown detached in Fig. 3. These polar sections, each indicated by the numeral 9, correspond in number to the number of core members 3. Each polar section 9 comprises a base portion 10 of substantially triangular shape, corresponding to the shape of its associated core member 3, and adapted to make contact with the upper surface of said core member when the face plate is in position.

Extending laterally and upwardly from each side of the base portion 10 are two series of spaced segmental projections 11 and 12, the projections 11 on. one side of the base portion 10 being staggered with respect to the projections 12 on the other side, so that each'projection 11 or 12 is in substantial alinement with the gap or space that occurs in the row of projectlons on the.

the center of the chuck, but in a rectangular chuck, having its polar sections parallel in a straight row, the projections would be of the same length throughout.

As herein shown also, it is referable to decrease the width or radial t icknesses of the projections 11 and 12 toward the center of the chuck in order to obtain near the center of the face plate a more finel divided area. This decrease in the widt of the projections 11 and 12, near the center of the face plate, is accompanied by a corresponding decrease in the width of the nonmagnetic gaps between said sections, as shown in Fig. 1. This feature contributes to the capability of the face plate for holding extremely small pieces of work, especially at the central portions thereof.

When two of the polar sections 9, 9, are

placed adjacent each other, in radial position, the projections 11, 11, of one of them enter between the projections 12, 12 of the other, as shown in Fig. 4. In the construction of the face plate as shown. in Fig. 1,

this method of assemblage is followed for the entire surface, and the proportion of parts is such that a nonmagnetic gap is formed completely around every individual projection 11 or 12, since the spaces between the projections 11 and 12 of each row are greater in area than the pro ectlons from the adjacent pole sections which enter sald spaces. The completed chuck face therefore consists, as show n in Fig. 1, of a plurality of rows of radially arranged sections or pieces, having radial nonmagnetic gaps 13, and also having concentric nonmagnetic gaps 14. In the assembly of the face plate these gaps 13 and 14 are filled with nonmagnetic material in the usual manner, as by inverting the face plate and pouring said nonmagnetic material so as to cause it to flow around each individual projection 11 or 12, and to completely segregate each projection from every other adjacent projection- The several polar sections 9, 9, of the face plate are each caused to interlock with the rim 8 by non magnetic material filling the gap 15, the latter being so constructed as to form interlocking tongues v16, 16, with the rim and with the polar sections 9. At the center, the polar sections 9 are suitably supported and insulated from the central block or bushing 17 by means of non-magnetic material fillin the ga 18.

Vhen t e face plate isin position, each polar section 9 is disposed in contact with one of the core members 3. Therefore each polar section 9 and its integral projection 11 and 12 is of the opposite magnetic polarity from the adjacent polar sections 9,

9, and their integral projection 11 and 12 on each side of 1t. Conse uently, the entire work supporting and olding surface of the chuck is made up of the projections 11 and 12 of these polar sections 9, giving thereby an extremely finely divided surface.

Each projection 11 or 12 is, as shown in Fig. 4, of the opposite magnetic polarity from every adjacent projectlon, both as regards those on opposite sides of it, and those at opposite ends of it. In view of this fact the number'of actual magnetic gaps presented by the face fplate is greatly increased, thus giving said ace plate the abilit to hold extremely small work at any an tion thereof.

It will be noted that the innermost projection of each polar section, on account of the extreme thinness of the base portion 10, is offset to such an extent as practically to overhang said base, it being clear that this construction permits the projections to be brought closer to the center than would otherwise be the case.

I claim,

1. In a magnetic chuck, a pole piece presenting a plurality of independent spaced flush surfaces, and an identical adj acent pole piece of opposite polarity presenting similar surfaces interposed between those of the first pole piece.

2. A' magnetic chuck, having a work holding face composed of a plurahty of indentical pole pieces, each of the latter presenting on said face a plurality of independent every porspaced flush surfaces.

3. In a magnetic chuck, a pole piece providing a discontinuous work holdin face composed of a plurality of isolate flush surfaces arrange in rows.

4. In a magnetic chuck, a pole piece providing a discontinuous work holdin face composed of a plurality of isolated flus surfaces arranged in staggered rows.

5. In a magnetic chuck, a work holding face comprising adjacent sections of opposite polarity, each section presenting on said work holdin face a plurality of independent flush sur aces disposed in alinement with a plurality of similar surfaces on adjacent sections.

6. In a magnetic chuck, a work holding face comprising adjacent sections of opposite polarity, each section having a row of upstanding spaced projections disposed in alternating relation to projections on adjacent pole sections.

7. In a magnetic chuck, a work holding face composed wholly of a plurality of rows of magnetized sections, each section being of opposite polarity from the adjacent sections in its row, and from the corresponding sections in adjacent rows.

8. In a magnetic chuck, a work holdin face comprising radially arranged rows 0 magnetized sections, the sections toward the center of said face being narrower, measured radially, than those removed from the center.

9. In a magnetic chuck, a work holding face comprising radiall arranged rows of magnetized sections, wit nonmagnetic gaps between adjacent sections of adjacent rows said gaps being narrower at the center of said face than at the edge thereof.

10. In a magnetic chuck, a plurality of magnetized pole pieces alternating in polarity, said pole pieces having isolated upward projections thereon Whose flush surfaces are separated by gaps of nonmagnetic material, to form the Work holding face of the chuck.

11, In a magnetic chuck, a plurality of magnetized elements alternating in polarity each of said elements roviding a row of spaced upstanding pro ections disposed in alternating relation to similar projections on adjacent elements, the flush surfaces of all 15 of said projections constituting the Work holding face of the chuck.

Dated this 27th day of February, 1919.

OAKLEY S. WALKER. Witnesses:

NELLIE NEALEN, PaNnLorn COMBERBACH.

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