US2946731A

US2946731A - Method and apparatus for electrolytic shaping

Info

Publication number: US2946731A
Application number: US621918A
Authority: US
Inventors: John J Falls
Original assignee: Standard Electrical Tool Co
Current assignee: Standard Electrical Tool Co
Priority date: 1956-11-13
Filing date: 1956-11-13
Publication date: 1960-07-26
Anticipated expiration: 1977-07-26

Description

.1.A J. FALLS July 26, 1960 METHOD AND APPARATUS FOR ELECTROLYTIC SHAPING Filed NOV. 13. 1956 3 Sheets-Sheet 1 'IHIIUIIHU.UllhunhHHHNHHHHHHHHHMHHHHFII INVENToR. @/amv d. 7245 July 26, 1960 J. J. FALLS 2,946,731

METHOD AND APPARATUS FOR ELECTROLYTIC SHAPING Filed No`v. 13, 1956 5 Sheets-Sheet 2 45 7 s: I 4f H5' i 46 i: i 6 55 I I l 5? 44 i l l s l l' g 9 i I E 43 l IT 4Z l A I l l i l f Il l z I 7 IN V EN TOR.

. Q/UH/v d. Hu a 3 Sheets-Sheet 3 1N VEN TOR.

July 26, 1960 J. J. FALLS METHOD AND APPARATUS FOR ELECTROLYTIC sHAPING Filed Nov. 13. 1956 ,/62 Z9 5 fr Jl dof/N d Hubs W/ MN/m J 6 A 2 f 6 w -w/z HHH@NNW 27u ll H M f5 @a United States Patent O METHOD AND APPARATUS FOR ELECTROLYTIC SHAPING John J. Falls, Cincinnati, Ohio, assigner to The Standard Electrical Tool Company, Cincinnati, Ohio, a corporation of Ohio Filed Nov. 13, 1956, Ser. No. 621,918

17 Claims. (Cl. 204-143) r[his invention relates to a method and apparatus for shaping metallic objects by the electrolytic process. Elec- .trolytic shaping involves the removal of material from a metallic object by passing high amperage direct current between a metallic object, or workpiece, and a rapidly rotating conductive wheel or disc moving in close proximity to the workpiece in the presence of a water solution of electrolytic salts. With the wheel or disc rotating in very light contact against the workpiece, material is removed from the workpiece principally by electro-chemical action rather than by the snagging action common to the ordinary abrasive wheelmethod. It may be said material is removed from the workpiece by a deplating or dissolving process which is performed as a direct reversal or opposite, of any electroplating process. Thus, in the practice of electrolytic shaping, the rapidly rotating wheel is not pressed into firm contact with the workpiece, and as a consequence, wearing of the wheel is greatly minimized. Notwithstanding the reduced pressure of the lwheel or disc upon the workpiece, material is removed from the latter at a rapid rate. l

Electrolytic shaping, commonly referred .to as electrolytic grinding, may be performed on a machine simulating the well-known snagging grinder, which includes a worksupport and -a rapidly rotating grinding wheel or disc, with certain modifications. In the practice of electrolytic shaping or grinding, the metallic workpiece isl kept charged with a lowvoltage high-amperage direct current of positive or plus polarity, while at the same time the electricity-conductive grinding wheel or disc is kept negatively charged. The workpiece and the grinding wheel or disc are electrically insulated from one another, except yfor the fact .that the current may passV from one to the other through a bath of liquid electrolyte applied at the area of contact between the workpiece and the wheel.

The wheel or disc may be fabricated principally of metal or other current-conductive material, with the working or grinding face thereof provided with an armor of minutely spaced abrasive particles of nonconductive material, an example of which is diamond powder or chips,

v which serves to slightly space the conductive material of the wheel from.- the workpiece as the wheel rotates lightly against the workpiece.Y The non-conductive varmor maten'al on the wheelface precludes metal to metal contact between the wheel and the workpiece, thereby maintaining a gap at the workpiece through which the low-voltage current will not -be short-circuited. This gap, however, can be bridged by. electrolytic fluid fed thereto, to pass current from the workpiece to the rotating wheel in performance of the electrolytic removal of material from the workpiece. In the process las outlined above, the workpiece ybecomes the anode in the electrolytic system, and the conductive Wheel becomes the cathode. K

The present invention is concerned with an improved method and means `for keeping Ithe workpiece and the rotating wheel properly charged continuously with op- 0r grinding of the workpiece.

j A 2,946,731 Patented July 26, 196g ice One object of the invention is to impose an electrical charge upon the rotating Wheel in such a manner as to avoid injury to the wheel driving spindle, its bearings, the housing supporting the bearings, and any other parts or mechanisms lassociated with .the spindle.

Another object of the invention is to so impose an electrical charge upon the rotating wheel, as Vto avoid injurious heating of the wheel spindle and deterioration of its bearings, as well as undesirable interference with proper operation of any spindle-driving motor which may have direct application or connection to the spindle.

A Ifurther object is to provide means for maintaining an electrical charge upon the rotating wheel without interruption, and with due regard to safe and trouble-free operation of the apparatus.

A still further object of the invention is to achieve the foregoing objectives and advantages with the use of simple, inexpensive, and highly elective means requiring a of servicing and shut-down expense, vital parts of the apparatus being so arranged and located that possible deterioration and damage thereto in service are practically eliminated. i

The foregoing and other objects are attained by the means described herein and illustrated upon the accompanying drawings, in which:

Pig. l is a side elevational view, partly in cross-section, illustrating an apparatus embodying the present inven tion, and adapted for shaping metallic objects by the electrolytc process.

Fig. 2 is a fragmentary cross-sectional view on an enlarged scale, showing va portion of an electricity conductive wheel ortdisc utilized in the grinding apparatus and process of the invention.

Fig. 3 is an enlarged fragmentary cross-sectional View showing details of construction at the upper or tail end of the machine spindle.

Fig. 4 is an enlarged fragmentary cross-sectional view showing a grinding wheel mount, this being a modification of the mount shown in cross-section at the foot of Fig. 1.

Fig. 5 is a view similar to Fig. 4, showing a. second modification of the wheel mount.

Fig. 6 is an elevational view, partly in cross-section, showing the invention applied to a twin-'wheel spindle.

With reference to the accompanying drawings, Fig. 1 illustrates at 8 a motor housing having opposed end bells 9 and 10 which enclose the field windings and the armature 12 of the motor. To the bell 10 is secured an extending spindle housing 13 containing suitable bearings such as 14 and 15, to rotatably support a rotary spindle 16 which extends through the bells and housing 8. Additional tbearing means 17 associated with bell 9 may be provided, contributing to .proper support of the spindle, as indicated upon Fig. 3. In the preferred form of the apparatus, the rotor or armature 12 is xedly mounted directly upon the spindle to drive same whenever the motor is energized.

The tool end, or the workingend 18 of the spindle, is

fashioned and equipped to detachably Ysupport the disc or grinding wheel 19, which rotates in a plane transverse to the spindle axis. The disc or wheel is rendered detachable in order to facilitate replacements or substituftions as may be required, due to wearing of the wheels, or to varying characteristics of different Workpieces to be operated upon. Workpieces formed of different types or grades of Various metals may be electrolytically shaped to advantage, with the use of dilering types or grades of grinding wheels. Any suitable or elective means may be employed for detachably mounting the wheel or disc 19 upon the tool end of the spindle, as for example, the socket-head screw 20 whose threads engage the internally threaded bore 21 in the end of the spindle. The head of the spindle end and a marginal portion of the counterbore 23 formed centrally of the wheel. A suitable key 24 may be provided, if desired, to lock the wheel against rotation relative to-the spindle. f

previously mentioned herein, the grinding wheel or dis .c. is `to carry an .electrical charge, and .will .therefore constructed wholly lor partly of metal or othercurrent conductive material. ln the form of wheel or .disc illustrated by Fig. l, the .entire body portion 25 is .of metal, and carries aiixed .facing 26 also of metal from which fa multitude of nonconductive particles 27 extend (Fig. 2.), The .nonconductive particles may be s tones, such .asdiamond chips or the like, minutely spaced apart and extended equal distances from the facing .material 26 as indicated upon Fig. 2, so that .the particles 27 .may contact.aworkpiece without placing the conductive `facing Z6 inactual electrical 4contact with the workpiece. A typical workpiece is indicated at W in Fig. l.

From the.foregoing, .it .Will readily b e understood that .the particles 27 of nnonconductive vrmaterial electrically insulatethe metallic wheel from the workpiece W, so that a Vlow-.voltage high-amperage electric current may Vnot ordinarily ,pass between .the workpiece and the grinding tvheelfre's-ti'ng thereon. Howeven'currcnt maybe caused to pass between the charged wheel .and the Voppositely 1charged workpiece, byintroducing between these elements a water .solution of electrolytic salts, commonly referred to as electrolyte. The electrolyte may be directed to the space between-the .wheel and the workpiece in any suitablemannenasby means of a nozzle 28 in Fig. l, or otherwise aswill be explained.

Referring to Fig. l, it may be noted that the workpiece Whats electrical vconnection at 29 with the positive pole of ,direct current source of electric energy, indicated as a igenerator@ whereas the grinding 4wheel or disc 19, as will be explained, is connected tothe negative pole of the 1ge,neratoror.,ou rce of .electric energy. The connection 29, ifgeird, may be applied 'l0 :the @titanic bed 0I' frame 30 of the machine, rather than to the workpiece directly, .provided that the workpiece is in current conductive cont Vith the .bed or frame during the shaping or grinding ope non.

lt highlydesirableito yso impose an electrical charge upon the grinding wheel or disc, vas to avoid various gliiculties Laffecting operation o fthe machine, -and the f. anoperator or attendant. For example, if the trical @Qlllltctiqtt is miadsfat Vtht grinding l .may be exposed to Vchemical or corrosive .estrolrts solution, .the @motion will S0051 il. @il et@ .and ret-lult@ revetement, with @essentiel n i C @liutslgwas 0f theme'Chlne @ad less '0f produ@- .Onthe other hand, if Vthe electrical connection be de ata location Vremote from .the electrolyte bath, for e, at the tail .end of the .spindle or upon the casing ,tlie apparatus, .the continuous passage of current th ugh the bearings and ,other vital parts of the machine v,cause,destructive electrolysis and corrosion of the due to electromagnetic interference occurring as the heavy direct current Vpasses the field and armature windings of the motor, producing eddy currents and magnetic iields incompatible with those of the alternating-current driving rnptor. At the very high amperages with which the electrolytic grinding process is commonly practiced, the drivmotor subjected. to Ainternal magnetic and electrical interference as mentioned above, may be irreparably damaged Withiny a brief period of usage.

"The present invention has as a primary objective, the lete elimination of destructive forces such as are I 'oned in the preceding paragraph. To accomplish Mm, V thecspindle is provided throughout its length with a boregor passageway 31, in which is supported, in spaced 4substarttial ,conccntricity with the wall of the bore, an sloeg??? .rod O r glement 32 of ,Copper 0r Qther highly .slgllltlvs @letal 0r matenal- .The CQnduQtQr wd .32 iS 5, overheating, vandra serious loss of motor eiciency l electrically insulated from the spindle at all points above or remote from the region of the grinding wheel or disc 19. In the region of the Wheel or disc 19, electrical contact may be established with rod 32 in any suitable manner, as by means of a metallic cylindrical bushing 33 which snugly embraces the lower end of the rod and has a close fit within the counterbore 34 of the spindle end. The bushing may be, steered within the .Spindle @lutterbore, a set screw 3S being suitable for the purpose.

From the ,foregoing explanation, it will be understood that an electric charge vapplied attheextreme upper ,end idiot-conductor rod 32, will be delivered directly to the grinding wheel through bushing 33 and the working end portion 18 of the spindle, without shunting or distributing any portion of the charge to the motor Vp12, the bearings l, 1S, 17, or to'other vital parts of the apparatus. The complete circuit, therefore, would comprise the generator, conductor 37, the workpiece W, the electrolyte upon the workpiece, thegrinding wheel 19, spindle end 18, bushing 33, *conductor odV 32,/ a drumor ring 38 atop the conductor rod, va brush 39 contacting the drum 38, and a return conductor wire 40 leading to the negative terminal of the generator. The drum 38; is of course va conductor Vofcurrent, and has electrical connection with the tai-l end 36' of conductor'rod' 32,2but not with the tail Vend 41 of the spindle.

Fora detailed disclosure of the construction at the tail end ofthe' spindle,vreference may be had to Fig. 3 wherein is `shown the spindle reduced in diameter to accommodate the ,bearing 17,-the inner race .42 of which maybe securedto the spindle by means of a nut 43. An end cap d4 on the motor casing enclosesrthe bearing, while permitting a portion of the spindle end 41 to extend therebcyond for accommodating an adapter 45 of 'insulating material, which supports the drum 138 and insulates it from the spindle and the motor casing. yThe central bore 46 of the adapter snugly receives the ltail end of -the spindle, and to ensure rotation of the adapter with the spindle,`a set screw 47 or other securing device may be furnished. Drum 38 rests atop the insulating Yadapter 45 and may be secured thereto in any suit-able manner, as by means of screws 43. A set screw 49 or equivalent means may tix the metallic drum 38 to the tail end l36 of conductor rod 32 as shown. Both the rum and the adapter are preferably concentric with the conductor rod, the latter extending into an axial bore Sil of the drum where electrical Contact is established between Vthe drum and the rod.

From Ythe foregoing, it will readily be evident that an electrical charge from brush V39 imposed upon the Ydrum 38 will pass to the conductor rod `32, the latter carryingV the charge directly to the tool end of the spindle for transmission to the grinding wheel or disc 19. As was previously pointed out, the conductor rod 32. is insulated from the spindle by reason of the air space between the rod and the spindle bore at all locations between the bushing 33 and the tail end of the spindle. ln- -sulation in addition to the air space may be furnished lbyrneans of one or more

insulating sleeves

51, 52, surrounding the conductor rod 32 and fitting nicely within 'the axial bore of the spindle. The insulating sleeve means Sil, 52 may be Vof one continuouslength, if desiredQand the preferred construction such sleeve means will ex- Itend' continuously along the conductor rod throughout "the length of the motor and its armature 12, to bar radiation of` magneticnflux and eddyV currents `from the rod to themotor windings and'poles. The insulating sleeve '5.1 attttlinglyris Shawn extending from the' lower bell lllll .0f the niet@ .Casing t0 the insulating .adapter 4S at Vthe remaining jbell 9. Thetail end ofsleeve 51 may abut from the spindle bearing 17, the adapter 45 may be provided with a depending annular lip 55 which moves in close proximity to a cooperative upstanding annular shoulder 56on cap 44 as shown in Fig. 3, .while a depending cylindrical extension 57 of the adapter rides closely within the bore 58 of cap 44.

With reference to Fig. 1, it may be noted that the electrical contact brush 39, whichbears constantly upon the metallic drum as the drum and spindle rotate in unison, is carried in a brush holder 59 that is insulated from the motor casing. The brush holder may be stationarily supported in any suitable manner, as by-means of an insulating bracket 60 carried by the motor bell, or cap 44.

With the apparatus constructed as set forth in Figs. 1, 2 and 3, Vthe motor casing 8 should be electrically insulated from the bed or frame 30, if the bed or frame is electrically charged through the workpiece W, as shown. This will avoid short-circuiting of the generator current through the motor casing. As an alternative, the workpiece W might be electrically insulated from the bed or frame, so as to carry the positive charge without transmitting any portion thereof to4 ythevbed or frame 30, in which event grounding of the motor casing upon the bed or frame would be inconsequential.

The possibility of short-circuiting the generator current may be reduced to a practical minimum by eliminating entirely all metallic contact between the grindingwheel and its drive spindle. vTwo methods `of accomplishing this are disclosed in the structures exemplified by Figs.

4 and V5. In Fig. 4, the grinding wheel comprises a metallic body 61 whichvis electrically insulated completely from the spindle 16, by means of the dielectric elements 62 and 63. Element 62 is an insulating sleeve itted in the central bore 64 of the body or Wheel 61, the sleeve being adapted to snugly receive 'the `tool end 18 of the spindle. An'annular flange 65 integral with the sleeve 62 may overlie the wheel body and thereby provide an insulating barrier against the spindle housing 13. 'For Asecuring the wheel to` the spindle, a lnut 66 may be applied to the spindle threads 67, to bearagainst Vtheinsulating washer 63 which in turn abuts the base 68 of a bore 69 inthe wheel. By this means or a suitable equivalent connection, thevgrinding Wheel may be fixed to the spindle for rotation therewith.

As in the previous disclosure, the electricity conductor rod 32 extends through the axial bore or passageway 31 of the spindle, from the working end or tool end, to the tail 'end where the brush connection from the generator is established, as in Fig. 3. A suitable insulating sleeve 70, or a series of such sleeves, may serve, to space and insulate the .conductor rod from the inner wall of the spindle bore. Electric current applied at the tail end of ythe conductor rod 32 is transmitted to the grinding Wheel 61 through a metallic terminal plate 71 which is bored at 72 to accommodate the rod, and the connectionmay be rendered secure, in any suitable manner, as by means of a set screw or fastener '73, It should be noted that the metallic terminal plate is free of any contact with the spindle, so that no current may pass to the spindlefrom the charged plate 71. v

'Ihe terminal plate 71 has electrical connection with the grinding wheel 61 at the screw or screws 74, which hold the plate iirmly `against a shoulder 75 ofthe wheel surrounding the bore 69. Electric current so brought to wheel 61 may readily electrify the ,grinding Wheel facing Y76, which `is similar to the facing illustrated by Figs.. 1

and 2. By reason bf the means described, .the grinding wheel and its `facing may be supplied with a negative electrical charge without inany way charging the spindle, its bearings, .orthe

casing elements

13, 10, 8 and 9. It will therefore be understood that the motorcasing may be xed to the frame or bed 30 of lthe apparatus without thev use of electrical insulation, and should an operator or `attendant inadvertently drop a wire, chain, or other Imetallic: object onto lthe motor casing andin Contact with 'theA machine frame, no dangerous shont-circuitiug of the high amperage current could result. The apparatus thereby is rendered safe to operate, and at the same time the motor, the bearings, and all other vital parts of the apparatus are protected against damage due to electrolysis and corrosion. The motor in any modiiication of the apparatus, Vis to be protected against damage due to eddyv currents and stray electromagnetic ux emanating from the conductor rod 3-2, by surrounding the rod with a Ysuitable insulator. This may take the form of a dielectric sleeve such as 51 of Fig. l.

Reverting momentarily to Fig. 4, it may be noted that the hub 77 of wheel 61 may be encircled -by an opentopped trough 78 into which a stream of electrolyte may 'be ted during rotation of the wheel, said troughhaving one or more downwardly directed jets or passages 79 to feed electrolyte continuously to the tacing 76 and any workpiece being ground or scrubbed thereby. The facing element 76 may be secured to .the wheel body 61 in any suitable manner, as by means of screws 80 passing Ythrough holes in the facing and anchoring into .the wheel body. By preference, the jets or` passages 79 diverge outwardly from the outer wall ot .trough 78, so that elecvtrolytejfrom, the trough will feed to the wheel I'facing lautomatically with the aid of gravity and centrifugal force.

In the inodilied structureV of Fig. 5, the entire body of the .grinding wheel or disc 81 is formed of hard insulation or dielectric material, an example of which is Micarta,r this wheel comprising Ia hub 82 axially bored at 83 to snuglyreceive the spindle end 18. A nut 84 applied toscrewthreads 85 on the spindle, bears against a suitable washer, 86 to iixedly mount the Vgrinding Wheel upon the spindle for rotation therewith.

As in thev previous disclosures, an electrical charge carried tothe tail end of conductor rod 32 by the brush 39, is transmitted by said rod directly to a terminal plate 87 of metal, Ahoused within a'bore 88 of the wheel body. By means `of screws 89 .and 90, or other appropriate expedient, the terminal plate 87 may be held in electrical contact With the wheel facing 91 and the tool end of the rod, as shown. N either the rod 32 nor the terminal plate 97 is to be in electrical contact lwith 4the spindleend or its nut 84.' Screws or other fasteners 92 in adddition to those indica-ted' at 89, may be employed for holding the facingelement 91'in iixed position relative to the wheel body 81.,` y d Y From the foregoing explanation, it should ,be evident that the grinding wheel facing-91 may be supplied with a negative electrical charge Without in any way charging the spindle, its bearings, or

thecasing elements

13, 10, 8 and 9. Accordingly, the motor casing may be -iXed to the frame or bed 30 of the apparatus without the use of electrical insulation. The structure of Fig. 5Y will therefore embody 'all the advantages and improvements specilied tor .the struct-ure of Fig. 4, including a maximum of safety in .operation due to the insulating nature of the 'entire wheel body 81. The body 81 may .be lfurnished any inclination including the full horizontal position, and depending upon the nature .of the :operation'to be per'- tormed, the diamond wheel facing may be applied tothe rim of the grinding wheel rather than to the'llat tace thereof. f i i y 'libe Fig. 6 modiication is illustrative of spindle structure such as might be employed lwhen the spindle is to carry two grinding Iwheels or

discs

95 and 96. `VIntl1is instance, two spindles 97 and 98 are aligned axially, with 7 their tailV ends 99 `and v100 separated as shown, butcou- 4pled ,son uthat the spindles may rotate in unison. The spindles. are .hollow as Previously explained, t @s99111- modat .elongate electric Current conductrsll and-102 which ,are insulated romthewinner of the spindles. Condntors 101 :and 10,2 may .0r may not abut 011@ er1- other Vendwise at their tail 4end portions, c leplending upon whether .or not both

wheels

95 and 96 are t0 be @ladrically .charged Smultaneusly .That iS?..if..;ths.CQ.I.1. .111.t0rS 101 arid .10.2 are t0 be. individual! abstenir the .tail ends of the conductors wopldfbe spaced fromone another, and .negative Charges from separat@ .Sources Of electrical energy Could lie .Supplied t0 @ach `intiivduilly by yWay of brushssllt 1104 wiping the metalli@ discs 0r 105m@ 'lseuredrespectively, to therods of condustOfS 101.1 and .10.2, The dises .0r drums 105 and 106 may be Separatedrhyscally and electrically by an insulating disc 107, as shown.

",Thefcharaters 10.8 and .169 indicate flanged @Dalers of dielectric material, each bored as `at llltl and 1412 to snugly receive the spindle ends, and such couplers may be keyed or otherwise secured to the spindles against relative rotation. The ilanges 113 of the ycouplers may be ,bored to receive a series of bolts or other fasteners l14 Whgh slamp the discs .0r drums 10S-19.6, along with .the insulating disc 107, tightly between the flanges Qf the Couplers.- ;By this means, pr equivalent Sirva-ture. the @mire ,assembly may be bound and unied for rotation asa single rigid spindlerstructure. As will beunderstood, the spindle sections `97-and 93 are to be journalled in bearings anywhere along their length, and rotation may berimparted'to eitherspindle section by associating a motor therewith as in Fig l, or more simply, by securing `a driving pulley-to oneof the sections.

In the event thatboth grinding discs or

wheels

95, 96 are to hechar-ged simultaneously with electrical energy, the insulating hdisc 107 may be omitted -and/ or the

oonductor rods

101, 102 may be -butted endwise or even joined together at their tail ends. Otherwise stated, the conductor rod may be continuous from wheel 95 to wheel 9 6, affording the conductor rod two working ends, 'or wheel ends, 1 15 and 116. The intermediate portion of lthe single rod which mounts the brush disc or drum,

would then have to be considered the tail end or tail portion of the conductor rod, within the portent of the claims appended hereto. It should be understood that the

conductors

117 and 118 transmit negative charges to the

brushes

103 and 104, originating preferably fromseparate generators or sources of electrical energy.

I f only one wheel is to be used 'for Velectrolytic grind ing, leaving the` other available for plain `or straight grinding, the Fig. 6 structure may simply eliminate one of the conductor rods, such Vas 101, along with its conductive disc -105 and the brush 103 .associated therewith. Mere omission of rod 101 would of course produce the same result; or if desired, the brush 103 might simply be omitted or held out of contact with its cooperative disc 105.

At the

locations

119 and 120, suitable electrical connections are provided between therconductor means 101, 102, and their respective grinding wheels or

discs

95, 96, these connections being in accordance with the disclosures of Figs. l, 4 or 5, or any other approved engineering practice. The space surrounding the

conductor rods

101, 102, within the spindle sections, may accommodate insulating sleeves such as are indicated at 70 upon Figs. 4 and 5, if desired. Whether or not such sleeves are in- ,eluded in the structure, however, the spindle bodies are insulated from the charges passing through the

conductor rods

101 and 102, so that the spindles will carry no electrical charge, this being one of the primary objectives of the instant invention as was explained in the Vdescription of Figs. 1 to A5, inclusive. The spindle sectiqns'of Fig. 6, when mounting the grinding wheels in accordance with Figs...4 and 5, .are fully insulatedfrom sletrialgharga The grinding wheel in some instances may be metalfaced o n the rim, rather than on the flat side face thereof, and the*A shape of the wheel may be altered as required, toV present various contours to the workpiece. Under certain conditions, the vdiamond chips or particles may be eliminated from the working face of the conductive wheel, without materially or objectionably depreciating the effectiveness of the electrolytic shaping or grinding process. The foregoing and various 'other modifications and changes in structural details of the apparatus may be resorted to, within the scope of the appended claims, without departing fromthe spirit of the invention.

:What is claimed is:

l. An electrolytic grinder for shaping an electrically charged V metallic workpiece, comprising in combination, an elongate driving spindle having a working end and a tail end, a casing including bearing meansrrotatably supporting the spindle near the ends thereof, means at the working end yof the spindle for supporting a current conductive grindingwheel in close proximity to the charged workpiece, and electric current conductive means electrically insulatedfrom the spindle, for directing an electric current from a terminal upon the tail end of the spindle directly to a portion of the grinding wheel, to impose thereon a vcharge opposite in polarity to the charge upon the workpiece.

2. Apparatus for shaping a metallic workpiece by the electrolytic process, comprising in combination, an electric motor including a longitudinally bored rotary driving spindle having a working end and a tail end, a grinding wheel nxed uponthe working end of the spindle for rotation therewith, said wheel including an electricity conductive facing to move in close proximity to the workpiece as the spindle rotates the wheel, an electric current conductive elongate rod supported in spaced substantial concentricity with the spindle -inside the bore thereof, said rod having opposite ends disposed near the ends of the spindle., means electrically connecting the ,grinding -wheel facing to the conductive rod at theworking end of the spindle, and means yfor applying to the workpiece, and to the rod at the tail end of the spindle,

electrical potentials of opposite polarities.

3. Apparatus for shaping a metallic workpiece by the electrolytic process, comprising in combination, an elec- -tric motor including an armature and eld windings,

and a longitudinally bored rotary driving spindle having a working end and a tail end, the armature being iixed tothe spindle and embraced by the field windings along Ya portion `of the spindle length, a grinding wheel fixed upon the working end of the spindle for rotation therewith, said wheel including an electrically conductive facing to move lin close proximity to the workpiece as the spindle rotates the wheel, an electric current conductive elongated rodsupported in spaced subtantial concentricity with the spindle inside the bore thereof,'said rod having opposite ends disposed near the ends of the spindle, means electrically connecting the grinding wheel facing to the conductive rod at the working end of the spindle,

ydielectric means interposed between the conductive rod and the motor armature for shielding the armature and field windings against interference emanating from the conductive rod when electrically charged, and means for applying to the workpiece, and to the rod at the tail end of the spindle, electrical potentials of opposite polarities.

4. Apparatus as specified in claim 3, wherein the current conductive elongate rod is insulated from the material of the yspindle throughout the full length of the spindle.

5. Apparatus for shaping a metallic workpiece by the electrolytic process, comprising in combination, an electric motorincluding Va longitudinally bored rotary driving spindle having a working end and a tail end, a grinding wheel fixed upon the working end of the spindle for rotation therewith, said wheel including an` electrically conductiveafa'cing armored with spaced and extending dielectric material, Yto contact the workpiece, an electric 4current conductive elongatedmd supported within the spindle bore in an electrically insulated relationship to the spindle, said rod having opposite ends disposed near the ends of the spindle, means electrically connecting the grindingwheel facing to the conductive rod at the working end of the spindle, and means for applying to the workpiece, and to the rod at'the tail end of the spindle, electrical potentials fof opposite polarities.

6. Apparatus for shaping a metallic workpiece by the electrolytic process, comprising in combination, an electric motor including a longitudinally bored rotary driving spindle having a working end and a tail end, a grinding wheel xed upon the working end of the spindle for rotation therewith, said wheel including an electrically conductive facing to move in close proximity to the workpiece as the spindle rotates the wheel, an electric current conductive elongated rod supported within the spindle bore in electrically insulated relationshipto the spindle, said rod having opposite ends disposed near the ends of the spindle, means electrically connecting the grinding wheel facing to the conductive rod at the Working end of the spindle, and means for applying to the workpiece, and to the rod at the tail end of the spindle, electrical potentials of opposite polarities.

7. In an electrolytic grinder, the combination which comprises, a longitudinally bored rotary driving spindle having a working end and a tail end, a grinding wheel detachably fixed upon the working end of the spindle for rotation therewith, said wheel including an electrically conductive facing to move in close proximity to an electrically charged object subject to grinding, an elongate electric current conductor disposed inside the spindle bore, and means electrically insulating said conductor from the material of the spindle, said conductor having an opposite electric charge to the wheel through the agency of `a conductor passing through the spindle bore from end to end thereof, electric current supply being directed from said conductor at that end thereof which opposite ends disposed near the ends of the spindle, means electrically connecting the grinding wheel facing-to said conductor at the working end of the spindle, a casing for the spindle, bearing means in the casing for rotationally supporting the spindle, and means for applying to the conductor at the tail end of the spindle, an electrical potential opposite in polarity to that of the electrically charged object.

8. An electrolytic grinder for shaping an electrically charged metallic'workpiece, comprising in combination, a casing including bearing means,V a longitudinally bored driving spindle rotatably supported by the bearing means, said spindle having a working end and a tail end, a grinding wheel iixed upon the working end of the spindle for rotation therewith, said wheel including an electrically conductive facing to move in close proximity to the workpiece as the spindle rotates the wheel, an elongated electric current conductorsupported in spaced substantial concentricity with the spindle inside the bore thereof, said conductor having opposite ends disposed near the ends lof the spindle, means electrically connecting the grinding wheel facing to the conductor aforesaid at the working end of the spindle, and means for applying to said conductor at the tail end of the spindle, an electrical potential opposite in polarity to that of the charged workpiece.

9. The method of electrolytically grinding a metallic electrically charged workpiece, with the use of a motor driving a bearing-supported metallic rotary spindle carrying a metallic grinding wheel, said method including rotating the spindle and grinding wheel relative to the charged workpiece, and transmitting to the wheel exclusively of the spindle, from a spindle-supported terminal remote'from the wheel, an electrical potential opposite in polarity to that of the charged workpiece.

10. The method o'f electrolytically grinding an electrically charged metallic workpiece, with the use of a motor rotating a longitudinally bored metallic spindle carrying on one end thereof a metallic grinding wheel, said method comprising rotating the spindle and grinding wheel relative to the charged workpiece, and supplying is remote from the grinding wheel.

l1. An electrolytic grinding wheel comprising a cylindrical body bored axially to receive a driving spindle, and having an electric current conductive face for exposure to a workpiece, said body being annularly grooved concentrically with the bore to provide an open-topped trough receptive of liquid electrolyte, said trough at its base being vprovided with o'penings terminating at the conductive face of the wheel, to direct electrolyte from the trough continuously to said wheel face as the wheel rotates.

. 12. A grinding wheel for application to apparatus for shaping a metallic workpiece by the electrolytic process, said wheel-comprising a cylindrical body bored axially to'receive a driving spindle, and means for securing the spindle within said bore, the body being 'annularly grooved concentrically with the bore to provide a trough receptive of liquid electrolyte, said trough at 4its base being provided with jet openings for releasing electrolyte from the trough as the wheel rotates, and an electric conductive facing on the wheel exposed to the workpiece, said jet openings terminating at said facing to direct electrolyte onto said facing.

13. A grinding wheel for application to apparatus for shaping a metallic workpiece by the electrolytic process, said wheel comprising a cylindrical body bored axially to receive a driving spindle, and means for securing the spindle within said bore, an electric current conductive facing on the body for exposure to the workpiece, the body being annularly grooved concentrically with the bore to provide a trough receptive of liquid electrolyte, said trough being provided interiorly thereof with jet openings for releasing electrolyte from the trough as the wheel rotates, the jet openings terminating at said facing to direct electrolyte thereto, and an armor of spaced dielectric particles on said facing extending outwardly therefrom, to entrain andk distribute the electrolyte upon the workpiece. v

`14. The grinding wheel as set forth in claim 13, wherein the body of the wheel is composed substantially wholly of dielectric material.

15. 'Ihe method of electrolytically shaping a conductive electrically charged workpiece, with the use of a motor driving a bearing-supported metallic rotary spindle carrying an electric current conductive shaping wheel, said method including rotating the spindle with the wheel disposed in lclose proximity to the charged workpiece, and transmitting to the wheel exclusively of the spindle,

' from a spindle-supported terminal remote from the Wheel Working end and a tail end, and a longitudinally extending bore formed therein, a shaping Wheel fixed upon the working end of the spindle for rotation therewith, said wheel including an electrically conductive facing to move lin close proximity to the workpiece as the spindle rotates the wheel, an electric current conductive elongate rod supported in electrically insulated spaced substantial concentricity with the spindle inside the bore thereof, said rod having opposite ends disposed near the ends of the spindle, means electrically connecting the wheel facing to the conductive rod at the working end of the spindle, and means for applying to the workpiece and to the rod at the tail end of the spindle, electrical potentials of opposite polarities.

17. A grinding wheel for application to Vapparatus for shaping a metallic workpiece by the electrolytic process,

said wheel comprising a V substantially Ycylindrical body bored axially to receive a driving Vspin/die and'having an upper and a lower face, means 4for detachably securing the vspindle within said bore, an electric current conductive facing-on the lower face of the Wheel to scrub a workpiece, means electrically insulating the `wheel body from the driving spindle, kand means `carried by the wheel body for directing an electrolytic liquid ltoward the ywheel facing, said last-mentioned means including an lannular trough formed in the upper sufaoe oi the wheel and having an open top, and atleast one jet passage extending from the lower portion of the trough to said lower Ysurface of 4the wheel, said ,jet passage thereby providing communicationbetween said trough and said lower surface of the wheel, said jet passage sloping from the bottom of said trough toward the outer periphery of said wheel so that when the Wheel is in operative position, electrolyte from the trough will feed to said `facing Vautomatically with the aid of gravity and centrifugal force.

References Citedin the file of this patent UNITED STATES PATENTS 390,439 Bradley Oct. 2, 1888 1,636,560 Hall July 19, 1927 1,720,731 Jones July 16, 1929 2,526,423 Rudor Oct. 17, 1950 2,739,935 Kehl et al. Mar. 27, 1956 2,741,594 Bowersett Apr. 10, 1956 2,798,846' Comstock July 9, 1957 2,826,540 Keeleric Mar. V11, 1958 OTHER REFERENCES Mueller: How to Grind Carb-ides Six Times as Fast, American Machinist, September 28, 1953, pages 122 and Keeleric: Elect-rolytic Grinding, Steel, vol. 130, No. 3page 84, March 17, 1952.

Claims

1. AN ELECTROLYTIC GRINDER FOR SHAPING AN ELECTRICALLY CHARGED METALLIC WORKPIECE, COMPRISING IN COMBINATION, AN ELONGATE DRIVING SPINDLE HAVING A WORKING END AND A TAIL END, A CASING INCLUDING BEARING MEANS ROTATABLY SUPPORTING THE SPINDLE NEAR THE ENDS THEREOF, MEANS AT THE WORKING END OF THE SPINDLE FOR SUPPORTING A CURRENT CONDUCTIVE GRINDING WHEEL IN CLOSE PROXIMITY TO THE CHARGED WORKPIECE, AND ELECTRIC CURRENT CONDUCTIVE MEANS ELECTRICALLY INSULATED FROM THE SPINDLE, FOR DIRECTING AN ELECTRIC CURRENT FROM A TERMINAL UPON THE TAIL END OF THE SPINDLE DIRECTLY TO A PORTION OF THE GRINDING WHEEL, TO IMPOSE