US1608677A - Magnetic chuck - Google Patents

Description

J. E. SEDERHOLM MAGNETIC CHUCK Filed August 2 1924 rolffz MIM" il O

Patente-d Nov. 3Q, 1926.

ENQ.

FATELNT JCI-IN E. SEDERHOLM, OF ST. PAUL, MNNESOTA, ASSIGNOR TO AMERICAN HOIST @s DERRICK CO., A PARTNERSHIP COIYIPOSED OF F. J. JOHNSON AND W. 0. WASHBURN,

F BAMSEY COUNTY, MINNESOTA.

MAGNETIC CHUCK.

Application filed August 2, 1924.

This invention relates to new and useful improvements in magnetic chucks designed particularly to hold and support a plurality of metallic articles such as castings, and the like, while being ground or machined, and more particularly relates to such chucks adapted to be mounted upon the usual reciprocating work table of an ordinary surface grinder, thereby to securely hold the work while being ground and finished.

Magnetic chucks, of ordinary construction, and such as are commonly employed at present, are not well adapted for use with surface grinders as a result of the prevalent danger of short-circuiting the coils or windings mounted therein, usually caused by water entering the chuck body and reaching the coils, it being necessary to have constant stream of water fiowing over the work and grinding 'wheel of such a machine during the grinding operation. Magnetic chucks, to be successfully used in connection with surface grinders, must necessarily be of water-proof construction so as to positively prevent any water or moisture from entering the casing or body thereof and reaching the coils with the resultant short-circuiting and burning out of such coils.

The novel construction of the magnetic chuck features in this invention is such that it will be impossible for any water or moisture to enter the body and short-.circuit the coils. lt is also designed so as to reduce to a minimum the magnetic leakage. The construction of the chuck is very simple and is such that it may readily be mounted upon the usual work table of a grinder, in either a horizontal or vertical position. 1t is pref- Virably provided with two complete magnetic circuits, thereby adapting it .to hold and support a plurality of both large and small pieces of work for machining in one operation. The interior of the chuck is filled with a suitable insulating medium such as oil .which functions to completely and thoroughly insulate the coils from all conductive material. The oil also functions to prevent moisture from entering the chuck-body and also to prevent the chuck from heating when in continuous operation.

The particular object of this invention therefore is to provide a powerful magnetic chuck of improved and simple construction, which may be etiiciently used 'in conjunction Serial No. 729,806.

with an ordinary surface grinder or similar device, without the usual danger of water entering the chuck body and thus causing the coils or windings therein to short-circuit and burn out. l i

Q A further and more specific object of the invention is to provide such a device having an oil gauge or receptacle mounted thereon which is in communication with the interior ofthe chuck body to allow for expansion and contraction of the insulating medium, and which gauge is also located at a point above the chuck body so as to create a slight internal pressure therein, so that in case of a leak in the chuck body the oil will ooze or leak out, thereby preventing water from entering the chuck with the resultant ruination of the coils and windings.

Other objects of the invention will more fully appear from the following descrip tion and the accompanying` drawings and will be pointed out in the annexed claims.

In the drawings' there has been disclosed a structure designed to carry out the various objects of the invention but it is to be understood that the invention is not confined to the exact features shown as various changes may be made within the scope of the claims which follow.

In the accompanying drawings forming part of this specification,

Figure 1 is a view in side elevation of a, portion of an ordinary surface grinder showing the improved chuck operatively mounted thereon;

Figure 2 is an enlarged plan view of the chuck removed from the grinder;

Figure 3 is a cross-sectional view on the line 3-3 of Figure 2;

Figure 4 is a similar view on the line 4 4 of Figure 2.-

Figure 5 is a detail sectional view showing the .connection of the reservoir with chuck chambers, and illustrating the adjustability of the reservoir.

The body of the novel chuck shown in the accompanying drawings comprises a rectangular metallic frame having end walls 11 and 12 and the side walls 18 and 14. A; relatively smaller frame comprising end walls 15 and 16 and side walls 17 and 18, is mounted within the larger frame as shown in Figures 2, 3 and 4. These two frames are secured to a metallic base plate 19 by means Figure S.

of screws 2l as shown in Figures 3 and 4. A bar 22, preferably oil*I larger cross Section than the sections or the two frames, is centrally mounted within the smaller rectangular 'tram-e yand in l.ine manner is secured to the plate 19 by means oi similar screws 2l. The walls. oi" the two rectangular frames and also oit the bnr 22 mounted within the smaller trame constitute the positive and negative poles or the chuck. ln the operation ot the chuck these poles will be energized to a* oct the articles placed in conT tact therewith as will be hereinafter described The means provided. lor enereizing or magnetizing the negativ and positive poles of theV chuck prerera` -I consists in the mounting or' a series of the space profided betr! en the valls oi' the two ames vand yalso tl e space between the bar 20 end the s rnnller rect-cogner frame. ln

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the drawings there are two such coils shown, an outer coik and an inner coil 241e, These coils are preferably connected in series, end currentis supplied thereto through the conductors 25, and 2G mounted in e. terminal boi: 2,7 suitably secured to the end Wall 12 ol the larger frame. A suitable non-niagnetic material such os babbitt 28 is interposed between the upper edges of the Walls of the two 'frames es particularly Shown in These upper edges of the two frames und also of the bar 22 are also preferably secured together by means of n0nmagnetic metal strips or bars 29 seated in' recesses 3l provided in the upper edges of thetwo frames `and the bar 22 and are suitably secured thereto by means ot countersunk screws Thus it will be seen that when the'chuck is assembled as obove described, the upper odg.. oi the walls of the two frames andv also ol the central bar A22 will be llush with the upper surface oit the.

bobbiit 2S und of the non-magnetic crossbars ln assembling this novel ol ick, the crossbors 29 are lirst secured to the edges ot the two 'frames and to the centrol bar 22, thereby retaining the Walls of the two trames end the bar i n para llelspaced relation. The structure thus for :assembled is then plfced on a face plate or other smooth surface ...i the bars 29 in contact therewith, after w h the babbitt is poured into the rspaces between the walls of the two frames and of the bar 22, thereby positively sealing the upper portion of the chuck body against leakage, as is clearly shown in Figure 9 Longitudinal c ooves 30 are preteri ,c Y p ably provided ir. the wells or thetwo trames and in thejbgu 2; into which the molten babi muy w n `o i. cure v anchor i` 4o Aie b tt lio tee l lU l tt tl weer the of@ ewes. ne im @c1523 are rthen Amounted 'in the. Chuck Y l g r te. scure o me 'o'toin the .lewe een .9 Se d t` *l blt. edges of the twov trames by means oi? the oils or windings in and from entering the body of the chuck withv the resultant danger of short-c1rcuiting and thereoreburning out ot the coils, a `Suitable insulating medium such as oil is preferably introduced in the spaces wherein tie coils ere mounted, thereby completely subroerffing the coils in an insulating oil with the result that it will be practically impossible for any moistiu'e to c me Vinto Idirect contact with the coils. To keep the body of the magnetic chuck completely' filled with oil, a gauge Si ispreferebly mounted in the end Wall 12 of the larger frame as particularly shown in Figures 2 and 5. rllhis gauge is so arranged with respect to thechuck body that the oil level therein will be above the upper wall or portion of the chuck and therefore above the oil level therein, thereby creating a slight internal pressure within the chuck body. F or the purpose of i'naintaining the reservoir in vertical position, Whatever the worlzing position of the chuck, the reservoir is adjustahly connected with the delivery con duit as at 4l, so that the saine head or pressure can always be maintained Within the chuck and coil chambers.A A suitable duct or ducts 41.10 are lpro yided in the wells oi the smaller rectangular 'freine of the chuck body in order that the oil nay circulate between. the two vcoil chambers.

In the operation oA the magnetic chuck here showinthe chuck as a whole is placed upon the usual reciprocating work table 35 oi an ordinary surface grinder as shown in Figure l. ln this figure, the chuck is shown mounted onV the work table in a horizontal position beneath the grinding wheel 36, indicated in dotted lines. When it is desired to macnine or surface-grind a number ofcastings or otherarticles, they will be placed upon the upper surface of the chuck es shown in Figure 2, each article being eo `recaer? trames and of the central bar 22 which function as positive and negative poles, the edges oit the walls 11, 12, 13 and 14@ of the larger frame and also the upper edge of the central bar 22 becoming the positive poles, and the upper exposed edges of the smaller frame becomingl the negative poles. Thus when a metallic article is placed in contact with a positive and negative pole and current is passed through the coils 23 and 24, :such article will be magnetically secured to the iace of the chuck without danger of removal therefrom until the flow of current through the coils 23 and 24- has been interrupted.

ln the operation of the chuck should a leak occur in the walls thereof', the internal pressure of the oil therein, caused by the oil level in the gauge 34. being above the level of the oil in the body of the chuck, will cause the oil to ooze or leak out of the fracture in the chuck body, thereby preventing any water or moisture from entering therein and short-circuiting the coil. Such leakage of oil from the chuck body will also serve as a warming to the operator that the body ot the chuck has been injured, and it will therefore be repaired before serious damage can result. In addition to the oil within the chuck body functioning as insulating medium for the coil and also to prevent moisture from entering therein it also functions as a means ot holding' down the temperature of the chuck when used continuously tor a long period of time.

It desired, the chuck may be arranged on edge upon the reciprocating work table of the grinder as shown in dotted lines in Figure 1. `When thus positioned, the gauge 34 will be rotated a quarter of a turn from that shown in full lines in the same ligure, there by maintaining the oil level above the surtace of the chuck body. Lugs 37 are preterably provided on the end walls 11 and 12 of the larger frame or body of the chuck to provide means whereby the chuck may be securely clamped or fastened to the reciprocating work table 35 when positioned as shown in dotted lines in Figure 1.

l claim as my invention:

1. A device of the class described, comprising a pair of pole 'trames disposed one within the otherl and spaced to provide an outer coil chamber between the trames, with the smaller frame providing an inner coil chamber, a reinforcing pole plate disposed medially of the inner frame, of less length than the iframe forming a coil support, a coil within each chamber, said outer frame having at its inner side adjacent one end, a cir-y cumferential groove, and said inner frame and pole plate having corresponding grooves on both sides, moldable material forming plates sealingly closing and connecting the frames and pole plate by engagement within the grooves, and a work-engaging tace plate detachably fastened to the opposite side of, and closing the frame.

2. A hollow chuck comprising two pole frames, one within the other, spaced apart to provide two intercommunicating coil chambers, a pole plate disposed medially within the inner iframe, magnetic coils, one in each chamber', the outer frame adjacent one side having a groove around its inner .tace and the inner trame and pole plate having the corresponding grooves on both sides, and plates otmoldable non-magnetic naterial in sealing engagement with the grooves, and a work-engaging `plate detachably secured to and closing the opposite sides of the trame.

3. A hollow chuck comprising two pole frames, one within the other, spaced apart to provide two intercommunicating coil chambers. a pole plate disposed medially within the inner trame, magnetic coils, one in each chamber, the outer fra-me adjacent one side having a groove around its inner tace and the inner frame and pole plate having the corresponding grooves on both sides, plates ot non-magnetic material in scaling engagement with the grooves, a work-engaging plate detachably secured to and closing the opposite sides of the frame, and a supply reservoir connected with the chuck and in communication with the coil chamber supplying oil for completely lilling the coil chamber, maintaining a head or pressure therein, and allowing expansion of the oil and in communication with the coil chamber supplying oil for completely iilling the coil chamber, maintaining a head or pressure therein, and allowing expansion ot the oil when heated, during operation of the chuck, said reservoir adjustably arranged to be maintained in vertical position whatever the working position of the chuck may be.

5. A reversible magnetic chuck, comprising a box-like chambered chuck body. having a work-engaging plate detachably joined thereto closingthe chamber on one side, a magnetic coil within the chamber, an oil delivery conduit communicating with the chamber, and a combined oil reservoir and expansion. chamber connected to, carried by ll l) and communieating` with the conduit and arranged at a level above the chamber for obtaining and maintaining ahead or pressure Within the chamber about the coil to prevent seepage of Water through a broken `joint in the coil chamber, whereby, if a joint in the chuck opens, the appearance of oil Will indicate a need of repair, While at the saine time Water is prevented from entering.

6. A magnetic chuck, comprising a plural piece chuck body including a Work-engaging plate detachably secured to and closing one side of the chuck having a plurality of interconiinunicating coil-receiving` chambers, an oil delivery pipe communicating With the chambers, an oil reservoir adjustably con nected with the oil pipe, and arranged above the level of the chamber for producing a head or pressure Within the chamber to prevent entrance of Water thereto by seepage, said reservoir movable with the chuclr and adjustable to remain in vertical position above the chuck, Whatever the Working positionvo'il said chuck.

7. A magnetic chuck comprising frames one Within the other spaced to form coil chambers one about the other, and containing coils, pole bars on one side transversely connecting` and securing the frames in spaced relation, inoldable non-magnetic niaterial 30 sealinel closinp the raines about the bars and a face plate detachably secured to andV

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