US2827740A - Polishing treatment for article surfaces - Google Patents

Description

March 259 T95 L. E. LEE 2827,74@

POLISHING TREATMENT FOR .ARTICLE SURFACES Filed Feb. 29, 195e d* J ai W" Iii-m LUTHER E.l LEE BY n l @/wmm l ATTORNEYS INVENTOR cles in' contact with the surface.

United States Patent POLISHING TREATMENT FOR ARTICLE SURFACES yLuther E. Lee, Takoma Parlnlvid. Application. VFebruary 29, 1956, Serial No, 568,686

A s Craims. (ci. 51-7; (Granted under Title 35, U. S. Code (1952), sec.V 2.66)

The invention described herein maybe manufactured and used by or for the Goverment of the UnitedStates of America for-governmental purposesv without the payment .of any royalties thereon or therefor.

The present invention relates to polishing treatment for article surfaces and more particularly relates to `an apparatusand a method -for abrasive-,type polishing which isautomatic inoperationand operates by means of a rotating magnetic fluid which vaiternately frictioually engages andreleases an article to be. polished as the article is reciprocated in themagnetic iiuid.

Prior artmethods of performing the function of the 'mvention includehand .and machine polishing by frictionally. contactingasurface to be polished with? polishing` cloths .or paper in the case of hand polishing, or with abrasives or polishing wheels in the case of machine polishing. Disadvantages of these methods are the short duration 4of effectiveness of the polishing clothes vor wheels ,due to the .abrasive particles becoming smooth and clogged after-.repetitions use, and the necessity for. close Vattention of an'operator to ,obtaina polish withoutmarring the .surface Yto he polished. Other disadvantages are -th'e-labortime involved, and the total time necessary to .achieve the job. as wellY as certain deficiencies inl theresult of the prior .art polishing technique,

Methods of obviating some .of thesedisadvantages have lbeen proposed, for example, in the patent to'P. K. A. Cuppers, Patent No. 2,664,676 for Finishing of `Workpieces issued January 5, 179-54, the work was inserted ina .paste of abrasives and then rotated. Otherlmethods at- .temptinv to obviate disadvantages of hand and machine vpolishing include the Method of and Apparatus for Cutting and the Like of A. G. Bodine, Jr., Patent No. -2,460,918,.issued February 8, 1949, and a ysecond patent tov the-same inventor for Method of and Apparatus for YCutting Materials, Patent No. 2,460,919, issuedV February 8,1949. Inthese patents polishing of the surface of an articley was made by contact therewith of abrasive particles suspended in an elastic medium by virtue of their movement induced by the drag upon such particles or .by .molecules .of Isuch medium moving in response to Vsound Waves propagated in the medium. These methods tried to overcome deficiencies in hand and machine pol- -ishing :methods by providing very light impact of the abrasive particles with the surface with very minute amplitude of the movement of the abrasive particles at high rapidity because of the high velocity of such parti- The above-mentioned Bodine, Jr. patented methods utilized a sound wave generator of the magnetostriction bar type which comprised a metal bar having wrapped therearound a coil of an electrical conductor and mounted to a bracket secured toV an' end Wall of a vessel which contained a fluidand abrasive particles. i A

Still other prior Vart methods are illustrated in the patents to H. N. Maier, Patent No. 2,591,083 issued April l, 1952, for Removal of Flash, Fin, and Burr and 2,827,740 Patented Mar. 25, 1958 "ice 2 I. C. Hackett et al., Patent No. 2,554,701 issued May .29, 1951, for Treatment of .Articles to Remove Somerof. the Outside Material .Therefrom or to .Polish the Same.

Both of the. latter patents used magnetic means to vibrate mechanical `elementsito cause abrasive-material to impiugeatagiven-rate on metal. ln these methodsgand means.diaphragms...vibrated the liquidcausing contact between the particlesrinsideto remove burrs from.the work'thereof.

.Hou/ever, allof Vthe Jabove enumerated prior yart :de-

.vicesghad `disadvantages of. not preventing damage .to the work, theinherentfslowness of operation, they were not adaptable to anepolishing finish .as provided by the instant invention, .and irl-.addition they did not remove V`dehcienciesof the oldfvhand .and machine methods in `that .the `Vabrasive,material tended tobecomelclogged` and to present increasingly-,diminished eiectiveness of operation.

"The present; invention overcomes these and many other defectsot the priorsart and in addition by the use .of theinventivamethod .and apparatus finer polishing is achieved, longer life of abrasive particles is permitted lar1d automatic operation may take place.

Accordingly, `21.n.obiect.of the presentinvention is V-to provideanabrasiveetype polishingrapparatus and means which isautomaticin operation by means of a magnetic fluid ,whichalternately frictionally engages A,and-re- 4leasestheartic'le'vto bepolished as the `article is reciprocated vin the magnetic uid whichfluid is simultaneously/rotated.

Another purpose of .the invention is to provide Vapparatus anda `method-for polishing metallic objects-.toa

high -iinish .wherein the polishing material willhave va `substantially continuous nand longer duration-oheectiveness yand which vwill obtaina polishwithout marring the surface tovfbepolished or `without causing `Vappreciable deviation Ifrom required ,size tolerances of the work.

Another ,aim ,ofthe invention isrto ,provide a polishing method and means Wherebvner polishing maybe achieved, whereby abrasive particlesutilized willhave a ,longerlifeand whichgis capable` of automaticoperation.

Another object of the inventionV is to provide .amautolmatic means vand `method ifor providing1 .a highly polished vsmooth rsurface on articles of various.forms'.which.do

not leaveobjectionable scratches onfthe polished. surfaces rand do not scuf, bnrnish, peen, or overheat the `work and abrasive particles are alternately magnetized'and demagnetized and with the compound motion resulting from Vthe Vrotating containerJ are vvoriented soV thatrdiierent cutting edges` or surfaces are presented Vto the worlcgritinuously thereby providing forlonger, in fact, practically inlinite life of the abrading materials and causing ia smootherand quicker operation. Y i

Other objects andrn'any` of Ythe attendantadvantagesof this Vinvention will bereadily appreciated as thefsane becomes better understood by reference to the following detailed description rwhen considered in connection with the accompanying'drawings wherein the gure diagrammat'ically4 presents partially in schematic andpartially in Apictorial erepresentationY an ,illustrative embodimentof V.a

preferred form of the apparatus of the invention with parts broken away to better show inherent operation of the device, the device being capable of utilizing the inventive method. Y i

Referring more particularly to the figure, a suitable container may have disposed therein a magnetic uid mixture of oil and metal powder intermixed'with abrasive particles 6. Container 5 which may be cylindrical in shape may be attached by suitable means as by welding (not numbered) to a iat disk member 7 on an upper face 8 thereof. Between the upper face 8 and the lower face 9 on the outer circumferential portion of disk 7 may be disposed asV by machining, for example, a continuous series of teeth -or serrations 10 adapted to be releasably engaged with a pawl member 11. Teeth 10 may be of a shape generally known t0 the art. in conventional pawl and ratchet mechanisms. suitably secured toa shaft member 38 disposed in a central aperture through disk 7 by conventional means as by splines or by key retaining means (not numbered). The lower end of shaft 38 may be suitably attached to a support member 12 which may in turn be iixedly attached as by screws 13 or other conventional means to a rigid support plate member 14.

Pawl member 11 may have a forward surface 15 adapted to engage the teeth or serrations 10 of disk 7 when in disk engaging position of the pawl member and may be slidably disposed to be reciprocated within a pawl bearing support 16. Pawl member 11 may be in the general shape of an elongated bar having a heel portion 17. In bearing relationship with the heel 17 of pawl 11 may be one or a plurality of c-ams 18 which may be eccentrically or otherwise mounted on a shaft 19 and held in place by suitable means such as abutment means 20 disposed on shaft 19. Abutment means 20 may be retaining keys as shown `or may comprise collars with a priate ats to receive the setscrew if desired. Shaft 19 may be Vthe output shaft of a speed reducing apparatus 21 which in turn may be driven by a continuously rotating or in the alternative by a variable speed motor 22. Ap-

A being connected in series with a suitable D. C. source 35,

Disk or turntable 7 may be setscrew arrangement and the shaft 19 may have appro- A n propriate pawl bias tension means 23 may be provided to *Y constantly urge the heel 17 of pawl 11 against the cam member 18 such that the forward portion or toe 15 of the pawl 11 may selectively engage and be disengaged from teeth 10 or disk 7 in accordance with the cam surfaces of the motor driven cam 18. Bias means 23 may be rigidly attached at one end to bearing support member 16 and at the other end may be attached adjacent the front end 15 of-pawl 11 by means such as hook and eye means 24. A second set'of cams 25 may be Ymounted on shaft 19 and spaced from cams 18 for a purpose to be described. YCams 25 mayl also be secured in predetermined longitudinal relationship along Yshaft 19 by key means 26, which means may be identical to abutment means 20. Detent means could alternatively be used-for this purpose if desired.

Driven by cam member 25 may be a pin member 27 'Y ditions within the coil thereby causing a magnetic` ux Vin a manner well-,known in, the art. Collector rings 30 and 31 attachedtoY terminals 32 and 33, respectively, may serve to carry current to and from the coils as is conventional. 'One end of switch 34 may be directly electrically 'connected to terminal 33, the other end of switch 34 tion ofl cam 25 causes pin 27 t-o alternately close and the D. C. source having its other end directly connected to terminal 32.V Closing and opening of Vswitch `34 by action of pin 27 in response to cam act-ion of cam 25 will thereby cause electromagnetic iields to be set up within the vessel or container 5 thereby causing magnetic energization of the magnetic fluid 6 yto cause the particles therein to orient themselves in relation to the magnetic eld set up in the container 5. lt should be realized of course that the inventive device is by no means to be restricted to a D. C. source, for example, an A. C. output may be directly connected to terminals 32 and 33 in place of the selectively opening and closing switch 34 an the D. C. source to thereby set up a varying magnetic el within the magnetic uid. A workpiece such as plug gage workpiece 48 requiring surface 39 to be polished may be suspended in alignment with the open end V43 of container 5 by means of a chuck or other work holdingdevice such as eye bolt means 44 shown. VAttached to the work holding means may be a bias spring 40 designed to obey Hookes law which in turn at the end opposite the work holding end may be secured by suitable means to a rigid support member 41. If the work is metallic `in nature or capable of magnetization, the work itself being disposed within the coils 29 will behave in solenoid action therewith and cause a vibratory longitudinally vertically upwards and downwards reciprocating motion by means of bias spring 40, the work thereby being alternatively dipped and removed from the magnetic fluid 6 or immersed deeper and shallower in the fluid.

It should be understood, of course, that should the work be non-magnetic in nature or incapable of solenoid action within the coils or conductors 29 in container 5 that .suitable other means to provide appropriate vibratory motion of workpiece'48 within the fluid may be provided such as, for example, by gear racks associated with the work holding means or by means disassociated from the means to hold the work so that the work may be moved in and out of or from one position to another Within the uid 6. As illustrated the work should be vibrated within the fluid in accordance with the laws of simple harmonic motion, subject, of course, to friction.

In operation the illustrative embodiment of the inventive apparatus performs as follows: rotation of the motor 22 imparted to the speed reducer 21 causes its -output shaft 19 to rotate cams 18 and 25. VRotation of cam 18 forces pawl 11 against bias spring 23 torbear against teeth 10 of turntable of disk 7 causing the disk to rotate in the direction of the arrow. Y This rotation as shown is interrupted rather than continuous, although Vit' desired mechanism for continuous rotation maybe introduced. Container 5 being rigidly secured'to disc 7 which disk is rotatably mounted upon shaft 8, also rotates causing some swirl` and rotation of the magnetic fluid 6. Simultaneously with rotation of the fluid rotaopen switch 34 to close the circuit at intervals at which time there occurs energization `of coils or conductors 29 Ywhich may be embedded in or otherwise suitably attached to ,container 5. If desired coils 29 may be spaced from or insulated from container'S. The .forming and collapsing of current through the coils 29 thereby sets up Ymagnetic elds which tend` to align the magnetic particles contained in the magnetic4 uid. The workpiece 38, if metallic', will be acted upon by solenoid action thereby'dipping into and out of or dipping deeper and more shallower in the magnetic uid 6. The Venergization of magnetic particles in magnetic Vfluid 6 causes theA abrasive particles therein to orient themselves to the surface of the article to be polished Yin such manner as to present abrasive edges in contact with the article.V The fluid reservoir or container 5 is Amounted for rotation on the rotatable wheel 7 whichis turned by the suitable pawl and ratchet means shown and `operated by the motor 22. Motor 22, as shown, isV

suspended in the magneticuidis thereby caused to reciprocate by the energization ofthe coil 29 ,and by Vthe resilient suspension means 40 in such mannerthat iiner vpolishing is achieved andtheabrasive particles continually present new abrasive edges in contact with ,the article. This preserves thelife ofthe abrasive particles and thereby insures optimum. automatic operation to eiect polishing by the magnetic `uid'apparatus and vmethod. Hence, the apparatus achieves automatic re- Vciprocation of the articles to be polished in combination with rotation of the container and contained magnetic liuid while alternately energizing and de-energizing the iiuid thereby eectively polishing the article which is held in reciprocative positions within the fluid.

Thus is provided an abrasive-type polisher which is automatic in operation and which utilizes a rotating magneticfiuid which alternately frictionally engages and releases the article to be polished as the article is reciprocated in the magnetic fluid thereby permitting extended duration of effectiveness of the polishing iiuid and preventing the abrasive particles therein from becoming clogged or smooth with use and wherein close attention of an operator is dispensed with and a line finished polish within close tolerances is achieved without marring the surface to be polished.

As heretofore stated obviously many modications and variations of the present invention are possible in the light of the above teachings. For example an A. C. supply hooked into terminals 32 and 33 can be used instead of the D. C. supply shown, in the case of polishing non-magnetic articles additional motion may be imparted directly or indirectly to the article to cause reciprocating motion of the article deeply and shallowly or within and without the iuid particle mixture, other continuous or discontinuous means for imparting motion to the turntable might be introduced, other switching means such as electronic switching means may be utilized, and other means to activate and deactivate the magnetic field may be instituted to impart the compound motion accomplished by the inventive method and apparatus to effect smooth polishing within close tolerances at a rapid rate which will be both effective and economical in use. In View of the many modifications and variations possible in the light of the above teachings it `is therefore to be understood that within the scope of the appended claims the invention may be practiced otherwise than as specitically described.

What is claimed is:

l. In a magnetic fluid abrasive polisher for materials comprising a rotatable member, intermittent drive means including a spring biased pawl in constant engagement with said rotatable member for rotating the rotatable member, a magnetic fluid reservoir xedly mounted on said rotatable member, means overlying said rotatable member and aligned with said reservoir to reciprocate the material to be polished within the reservoir, and energizing means to alternately activate and deactivate the magnetic iield in said uid whereby the magnetic particles in said fluid present in each energization a different contact surface to abrade the article.

2. In an apparatus to polish materials comprising a rotatable member, a support member to support said rotatable member, an open ended container for magnetic fluid rigidly attached to said rotatable member, means to reciprocatingly support a workpiece of the material disposed in vertical alignment with the opening to said container member, drive means including a spring biased pawl in constant engagement with said rotatable member for rotating said rotatable member intermittently, means disposed on said container to alternately activate and deselectively energize andfdeesersiZQ-Said.- divaftlsasaus, thereby permitfneabrasiv Particles nsad fluid whecorne lcontinually oriented innresponse lto the Vmagnetic `held selectively setup at intervals therein itopresenta different abrasive contactV surfaceto, the workpiece at each p energization.

3. VPolishing apparatusifor polishing workpieces cornprising a support plate, means ixedly, attachedto said supportplate to supporta rotatable shaft,taidiskmember having an upper facea`lowerface and a circumferential edge portion, thedisk member being ixedlysecured to said shaft to rotate, therewith, teeth members disposed on the circumferential edge portionsof Asaid disk member, a container for magnetictiuid rigidly attached `to and concentric withrsaid disk member, said container having an `upper open end, a lowerclosedfcndanda cylindrically shaped wal1,work.lsuspensi0n means disposed in yalignment and concentric with l.the open end ofsaid .container to reciprocatinglyjsupport a workpiece for longitudinal motionin a vertical Vdirectionupwards and downwards relative to and inside'the container, a ,magnetic uid comprising oil, metal` powder-,andiabrasive` particles retained within said container,` pawl meansadapted `to engage the ,teeth of the disk membertoimpart thrust for rotation of the disk member and shaft, cam means to drive said pawl means into and out of engagement with said disk teeth, means to rotate said cam means, means to interruptedly establish a magnetic tield within said container to orient the abrasive particles in the iiuid contained therein, rotation of the container and its magnetic iiuid combined with reciprocating motion of the workpiece and energizing and deenergizing of the magnetic field to orient the particles in the magnetic iluid thereby permitting polishing of the workpiece within close tolerances, the magnetic particles in said fluid presenting different contacting surfaces to abrade the article at each energization.

4. Apparatus for polishing a workpiece, said workpiece being supported to reciprocatingly move upwards and downwards in a vertical direction, said apparatus comprising a container having a cylindrical wall closed at one end and an upper opening at the other end thereof aligned with and of size to receive the workpiece, a substantially disk shaped rotatable member rigidly secured to the closed end of said cylindrical wall for supporting said container, a magnetic liuid comprising a mixture of oil, metal powder and abrasive particles retained within said container, means to rotatably support said disk member, interruptedly applied means including a spring biased pawl in constant engagement with said disk shaped member for `rotating said disk member gradually, means including a coiled electrical conductor disposed within and forming a part of said cylindrical wall and extending substantially the full length thereof for selectively establishing and disestablishing a magnetic eld within the magnetic uid to cause the particles therein to align themselves in relation to said workpiece, motion of said workpiece in an up and down vertical direction combined with energization and deenergization of the magnetic iiuid, accompanied with rotation of the container thereby causing the particles in said uid to present a different contact surface to abrade the workpiece at each energization thereby causing rapid energization without damage to the magnetic uid.

5, A magnetic tiuid abrasive polisher for materials comprising a first rigid support member, a second sup port member mounted on said first rigid support member, a shaft member mounted in said second support member, a turntable member rotatably mounted on said shaft, a container member having a lower closed end, a cylindrically shaped sidewall and an open end rigidly attached to and concentric with said turntable member, electrical conductor means wound in said container, a magnetic iuid of oil, metal and abrasive particles retained within said container, energization of said coil causing orientation of the magnetic particles containedtherein,

-reciprocatingmeans to support a workpiece 'ofthe mate- Vrials in alignment with the openend of said container, to thereby cause the workpiece to move into and out of the container in response to mechanical actuation of the reciprocating support means by the workpiece, a rst collector ring and a second collector ring disposed concentric with the periphery of cylindrical portions of the container, a contact means bearingly supported against Yeach of said collector rings, means to actuate said con- Yclose, a shaft supporting said first cam member, a second cam member mounted on said shaft, a motor to impart rotational movement for driving said shaft, a pawl member, a bearing support to slidably receive said pawl member for lateral motion therein, said pawl member having a heel portion and a toe portion, the heel portion being 8 c Y in abutting relationship with said second cam to be driven thereby in response to rotation of said cam supporting shaft, means disposed on the circumference of said turntable member adapted to be driven `bythe toe of said `pawl member, said pawl member coming into engagement and disengagement selectively `with the means disposed on said turntable member to cause turntable rotation in response to actuation of saidrsecond cam, bias means dis-V posed between said bearing support and the toe of said pawl member to constantly urge the pawl kagainst the second cam surface, motion of the Work in reciprocating directions into and out of the container accompanied by rotation of the container'and selective energization and deenergization of the magnetic fluid contained inthe container causing the magnetic articles in said fluid to present 1 a dierent4 contact `snrface to abrade the workpiece at each energization.

References Cited in the le of this patent Y UNITED STATES PATENTS 2,480,502 l Nieder Aug. 30, 19,49 2,664,676 Cuppers Ian. 5, 1954 2,735,231 simjian Feu 21, 1956

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