US2005851A - Valve seat grinder - Google Patents

Description

June 25, 1935. F. o. ALBERTSON 2,005,351

VALVE SEAT GRINDER Filed July 19, 1954 zsheezs-sneet 1 Patented June 25, 1935 I PATENT" EFF cs I Thel'present invention relatesrtosvalve: seat; grinding-machines :ior. the .forming; reconstruc-yticn orirepair ofizvalve seats zof zinternal :combusw tion' engines. and is particularly concernediwith an2' improved: angularsattachmentz for: grinding;

machines oflth'e typecovered byimy 'pri'orzappli' cation :Serial No, 711,848. filed iFebruaryi 19; 1934:v

entitled Valve seat grin'ding. machines:

7 Valve grindingmmachines SOf-lithfi'l priorr'art may: 10c be classified into'. machines of; thevful ld contact type in which the stone is in contact withthe:

working surface toib'e ground throughout :the. entire peripheryof i the I stone; and; singleccontact: machines in which the stone is; so i tiltedzzthat it" 'con tacts only one side of the :valve; vorr'the :stoner may be arrangedieccentrically with'respectitoitheaz axis of revolution,

The: devices ofv the prior"artx have; however;v beeni very comp'licated; requirin'gieither a= com-*- plicated; mechanism: for rotating and"; revolvingi; the stone, 01-1. requiring a; ballbearing-'itoolaholderi' for supporting the stone, and:.the devices :of the r priorzarthave not heenable toi'grind'. the valves;

with a suitable finish. i 1 The difiiculty with" the .full' iseatfcon tact grinding ;wheeis "of r the prior art was: that this:;resu:1t-.:

ed'in' clogging onloa-dihg ofithe wheel itwithii the: cuttings or material groundzfromtthex seat, and

this caused a changein thecontour'ofthe stone." H andresulted' inrthegrooving-iof the valvecseati.

All the devicesrof the prior art-wereaa'lso.veryxexepensive (in-account of the complicated? mechav-v nism required and on account :Of'lthe apparent nes cessity for using anti-friction bearings andisuch r.

do of the ordinary. garage ownersg who' could inott afiordt expensive mechanism" and make a profit on the work to be done.

One of the obj ects' of the present invention is the "provision of: an improved apparatus =for ree constructing or grinding valve seats of 'very;'hard material, such as stellite; tungsten steel 'orAo-ther:

hardened alloys and which apparatus :iswpeculiar.

ly adapted to be utilized-on the-valves which are; disposed inirelatively inaccessible.positions such 1 asthevalves of thedast cylinder: which maybe underneath the dash.

Another ohjec-ti ofthe .invention -.is ther provision of an angular attachmentforval-veseat 5 grinders-of the class described-Which is/adapted, to bexsecuredl to-any kind of a motor/ drivel" to adapt-the'motor driver to the operationofl aw valve seat grinder of thetype covered byqmyvrprior i I application; M Another-object of the invention'is the provi face'on'the Ka a-liver.

. devices could "not be brought witlflmthe means-- sioni'of (an; improvedzgrindingztool 0f=the ful-lvseat. contact i. type which is 1' adapted; to eliminate the: clogging and-loading of the grindinggwheel or the grooving: otithe rseat; landxtoprovide a :grinding; tooltwhichisseit cleaningr v Another; object ot the invention is the prov'rsiona ofi-an :improved': grinding-a wheel adapted ;.to:

disperse: the rcuttingszicontinuously; and to pre' ventzloadinga of th'eazwheel' or filling ,.--with- :the cuttingsof theaintersticesfbetweenthe abrasiveeparticles 'of thawheel at the surface; the cuttings -=be-.-' ingfi dispersed: r by icurrent 1 ofazair and centrifugal:- force; ,atithesrperiphery, o)?- the: wheel when 1 the}: wheel is lifted-periodically; from the seat; 1 v

Another object of the invention-isgtheaprovision:" of. air improved method 5 and apparatus which lie adaptedizto -disperse:the cuttings by; meansizoiiz a; vibratory movemen-tiof thestone either'in'zaever- ,tioal-idirectionronutheepilot or angularly; inalateral direction :by;meanseof-ithe fiexibilityvof the: pilot,- so as to prevent loading of/ thei-wheel-iand :5 grooving of the seat and tozprod-ucea finishedsum Another w object of; the inventionris the provi+= sion.:.ofi: an improv'edmoolz assembly-, includingga motoiedriverand auniversal connection between: the lmotor 'idriver landrthez grinding wheel; include ingmmeansrforieliminating rdetrimen-talkshocks:onv; v

theigrinding;wheel butadapted to producea-duaik l V action ofgrindingca-nd r dispersioniof fthe"ClltT/ing5r' 300;, byz' ansflfi a s gl'e"grinding-Wheel mounted: for: full contact with the seat.

Oct-her obiiectstandvladvantagesx of th'erin vention W-iH- bfin apparent from the following;descriptionr: and .fronr:thereccompanying':drawings; .in which a 3511 similarcharacters rot reference"- ind-icate similar. parts throughout the several views;

Referring to the drawings, ,oatiWh-ich .ther'ea'areatwo'z-sheets -Figi 1 isasideeelevational view ofta valve: seat grinding apparatus constructed: ace 40c cordingtoythe presentinvention and including; the: improved angular attachment which -facilitates-themse-t of aegrinder'. on valves underneathn the--:dasl-1.;-\ I I Fig. 2- is .a vertical sectional View of the valve: seat grindinghwheel tool holder and angularate tachment showing. a portion of the driverin elevation;

Fig, 31; is. an. enlargedfragmentary sectional VieW- showing thedriving connection. between-.5 the drive shaftof'th'e angular attachmentandl the-toolholdem. i

Fig-.- 4 isla sectional. view-taken. throughthehuh: which surrounds the a driving: shaft of; the. motorLdriver on. the plane of thelline- 4-;4 off mounting for the drive shaft of and I view of the bevel gears utilized in the angular driving attachment, also showing the resilient the attachment,

Fig. 6 is a front elevational view of the spring utilized for resiliently mounting the drive shaft of the angular attachment.

Referring to Fig. l, the complete assembly of the present grinding apparatus preferably. includes the motor driver 20, a tool holder 2|,

an angular driving attachment I9, a grinding wheel 22, and a pilot stem 23. V

The apparatus is illustrated in connection with a valve seat consisting of a hardened metal ring 24, which has been fixedly secured in the block 25 of an internal combustion engine having" a valve seat guide 26.

The. pilot 23 is preferably of the type having a lower cylindrical part 21 which fits the substantially cylindrical part of the valve stem guide 25 very closely, within one thousandth of an inch, for the purpose of centering the pilot 23 in the guide and locating it axially ofthe'guide.

The pilot is also preferably provided with a very gradually tapered portion 28 which extends down into the upper part of the valve stem guide 26 and may be fixedly wedged in the guide by merely shoving the pilot downward. The

taper. is preferably about twenty-three thousandths of an inch per foot, and constitutes the sole means of securing, but any suitable taper 1 may be used which will effect the wedging action "and secure the pilot.

' Another type of pilot which may be used is the expanding pilot shown in my: priorPatent No. 1,902,207, issued March 21, 1933;'

wound type provided with suitable speed reduction gearing and having a downwardly project ing drive shaft for driving the tool holder 2|.

The present grinder assembly is particularly adapted to be: used in grinding'valves when the engine block issupported by the chassis, by the angular attachment l9,v which enablesthe operator to reach inaccessible valves which may be 'underneaththe dash l8 or madeinaccessible by other parts of the automobile frame ormechanism. 1

In the prior application described the motor. driver is provided with a shaft resiliently mount-' ed foraxial movement in order to permit vibraand therefore it is not essential that the motor driver be provided with aresiliently mounted and axially movable drive shaft when the angu lar attachment is used, since the angular ate tachmcnt has its drive shaft so mounted.-

The motor driver 29 is provided with a hous ing having at its lower end a substantially-cylindrical portion 29 surrounding the motor drive shaft 30, which is provided with a non-circular (hexagonal) end 3|.

The angular attachment l9 isprovided with a substantially cylindrical socket 32 fitting about the cylindrical portion 23 of the motor driver 20, and the housing 33 of the angularattachment is provided with laterally projecting lugs 34, 35 spaced from each other at 36 and adapted to be drawn together by a screw bolt 31 which passes througha cylindrical bore 38 in the lug 35 and is threaded into a'threaded' bore 39 in the lug 34. H

- When the lugs 34, 35 are in spaced relation to each other at the point 36, the cylindrical socket 32 of the attachment housing 33 fits about the cylindrical portion 29 of the driver 20, and there,- fore it may be clamped in place by drawing the lugs 34, 35 together with the screw bolt 31.

Socket 32 is preferably provided with an annular shoulder 40 which engages the end of the cylindrical portion 29 of a motor housing 20,

thereby'determining the final assembled position of these two parts.

i fThe attachment housing 33 preferably com cylindricalportions 4|, 42 being arranged at an i erally with respect tothe tool holder 2|, ancL;

when the drive-shaft of the angular attachment is engaged with the tool holder 2|, enables the 'motor' driver to be used without interference with the over-hanging dash 8 of the automotive vehicle.

The housing portion 4| of the angular attach-.- ment is provided with a bore 43 terminating at the annular shoulder 44 for receiving and seating the outer race 45 of the anti-friction bearing, which also includes the ball bearings .46 and the inner race 41. Each of these races preferably has the partially circular ball groove for receiving the balls 46, and the inner race is preferably turned down at 48 to receive the inwardly projecting sheet metal seal 43, which is carried by the outer race by being secured in the groove 56 formed by spinning over the top of the outerv race 45.- v i The anti-friction bearing 45, 45, 4! is secured in counterbore 43 by means of atubular threaded member 5|.which is threaded into the larger bore 52 to engage the outer race 45 and clamp it against the annular seat 44. Tubular threaded member 5| maybe provided with an inwardly projecting flange Y53 and with an aperture 54 for passing the driven shaft 55. 55 comprises a' stub shaft having a reduced threaded portion 56 upon which is threaded'the special pinion 51. The stub shaft 55 is also provided 'with an annular shoulder, and a larger the I cylindrishaft 55 is provided with a non-circular (hexa gonal) socket 63 adapted to fit the complementary hexagonalend 3| ofthe drive shaft 35 of the motor driver 20. p

The driven shaft 7 The'drivenshaft 55 may be fixedly secured by the clamping action of the special pinion 51, which has a threaded bore 64, and the pinion clamps the inner race 41 between 'the pinion and annular shoulder 6|. Driven shaft 55 is thus rotatably mounted by means of the anti-friction bearing 4541 in proper position in the housing portion 4| to be engaged and driven by the drive peripherally oi the races.

l I aooassr 1- shaft 30 of the motor driver -20 when the angular? attachment 1 9 is clamped on the'hub 28 of motor driver 26. In order to provide a better seat for the outer race 45 a steel washer 65 may' be inter posed between the outer race 45 and the annular shoulder 44. i

The specialpinion might gear, as it performs the functionof'a bevel gear meshed with another special pinion 66 carried by and housing portion 42, thus permitting the -re s'ilient mounting of the drive shaft 61, and the width of the tooth spaces 10 between the teeth 69 is also adapted to permit movement of the teeth of one pinion into the tooth spaces Ill between the teeth of the other pinion so as to effect continuousengagement but permit axial movement of the drive shaft 67.

The housing portion 42 counterbore ll terminating in an annular shoulder I2 against'which is'seated a steel washer 13. The steel washer it provides a seat for a resilient spring washer M, which is shown' in perspective in Fig. 6. Ihis spring washer M comprises a flat annular metal member having a plurality of peripherally extending tongues located about the bore 16 of the spring washer l4 and bent downwardly to engage a second steel washer 11. Three or more of the resilient spring tongues 15 are preferred in order to provide at least three point resilient support for-maintaining the re silient projection of the shaft 61 from the housing42. m The outer race 18 of the anti-friction bearing, which comprises the races 18, balls 19, BI! and inner race 8|, is provided with an outer cylindrical surface slidably engaging the counterbore H so that the entire anti-friction hearing may slide axially in the bore H. l j c The races'lb; 8! are provided'with the usual partially circular grooves for receivingthe steel balls '19, as, and the balls maybe provided with the usual cages for holding them in predetermined position spaced with respect toeach other The housing portion 42 is providedwith an enlarged counterbore 82, which is threadedto receive the threaded member '83, which has an inwardly extending flange 84 surrounding the enlarged bore 85, which passes the end of the drive shaft ill. The flat end of the threaded member 83 engages the end of the outer race 18 and acts as a stop to limit outward sliding movement of the race 18, the threaded member 83 being driven. home in itsthreaded bore 82'.

' The drive shaft 6? is preferably provided with a non-circular (hexagonal) end portion 86 and a tapered irusto co-nical portion 81 for engaging an oil seal. The threaded member 83 provides a housing for an oil seal, which may consist of a hat leather having an outwardly extending radial flange Stand a cylindrical flange 89. The cylindrical flange 6 engages the tapered part 81 of shaft 6? and may be held in engagement with that part by an endless helical garter spring 90, which continuously draws the cylindrical flange 89 of leather against the smooth metal part til-and prevents egress of lubricant at this point.

The radially extending flange 88 may be clamped against the flange 84 by means of a metalbe termed a bevel washer 9i ,whichin turn is engaged by the tubular spring housing 52 ing 92'has an inwardly extending radial flange 93, which engages the end of the outer race 18 and holds the spring 93 in proper position.

The drive'sha'ft S'l also has a reduced cylindrical portion 94 which-fits in the cylindrical bore "of the inner race 8!, and the end of the inner race.

ill engages the annular shoulder At its upper end the drive shaft is provided-with a reduced The tubular spring houS- I threaded portion 96, upon which is mounted a suitable spacing member iii, and the inner race 8i isclamped between annular shoulder 95 and spacing member er by the special pinion 66, which has a threaded bore 98.

'The'inner race s1 is thus fixedly secured to the drive shaft in and adapted to move with it both in a rotary direction and an axial direction, while'the outer race 78 is adapted to slide in an axial direction in the counterbore H against the compression of the'spring "l4.

'-The non-circular end 86 or driving knuckle on i shaft 67 is preferably provided witha flat end 'isprovided with a 99, which is charnfered as at 5-90 for the purpose of removing the sharp edges which would other" wise wear, so that the physical characteristics of tor driver preferably operates at a speed with-' in the range of 13,000 RA. P. which is'c'onsiderab-ly'in excess of the speeds previously used by the drivers-of the prior art, and the'mecha'nism is capable of operation at this high speed without the necessity for anti-friction bearings inthe tool holder on account of thefact that there is no bearing load on the bearings of the tool holder except that which is involved by its guiding'iunction.

The tool holder 23 preferably comprises 'a substantially cylindrical housing sleeve ml; which may serve as a handla and which may beconstructed of a fiber tube, phenolic condensation compound, or other suitable material.

The housing H3! is supported by 'meansof a supporting body or sleeve m2 of substantially cylindrical outer form and provided withthe radially outwardly extending flange I03 at its lowerend adapted to be located flush with the outer surface of the housing HHQ Flange l B3is provided with an annular shoulder led adapted to receive the sleeve or housing 2i, and the supporting sleeve m2 is provided with a downwardly extending tubular portion li55,'which is externally threaded for the purpose of receiving the threaded hub we of the grinding wheel. The grinding wheel 22 comprises a suitable grinding stone of carborundum, emery, or, other suitable material, which is secured t o'the tubular hub I06 by means of cement lUl'. On its upper surface the grinding stone 22 has a cardboard annulus or washer I08 cemented thereto, bearing the-data regarding thesize and angularity of the stone. The upper surface Hi9 of the grinding stone is flat, and the periphery lid is substantially cylindrical. The bottom Illpis preferably flat, while the working surface H2 is accurately the rotation ofthese parts, so that the wheel will we and tubular be driven home on its threaded support by the action of the driver.

The supporting sleeve I02 is provided witha. cylindrical bore II 3 extending throughout the major portion of the sleeve and with an enlarged counterbore H4 at the top. The counterbore I I I4 is threaded at its upper end II-5 for receiving the end of plug'l I6, which has a reduced threaded end II'I threaded into the bore H5.

End plug H6 has an outwardly extending annular shoulder H8 which engages the end of the sleeve I02 when it is threaded home therein, and

itis also preferably provided with a cylindrical surface H9 and the annular shoulder I20, the

former being received in the housing IOI, and the latter abutting against the end of. the housing IOI-for supporting the upper end of the housing IOIon the sleeve, IOI, I02.

Pins I2I may be driven through the housing IOI into the bores I22 in the reduced portion In of plug H6 firmly to secure all ofgthese. parts together and prevent the threaded parts from coming loose,

The end plug 1 I6 is provided with a bore I23 extending through it, and the bore I23 emerges into an enlarged recess or counterbore I24. The intervening surface of the plug is frusto-conical at I25 to provide a suitable clearance between the central part of a spring washer I26and the parts of the end plug H0.

The spring washer is illustrated ingre'ater, detail in Fig. 3 and comprises a resilient tapered steel member I26 circular in plan andpreferably provided with a centrally located aperture I2I.

' The spring washer is preferably provided with a plurality of radially extending rib formations I 28, which in this case are located on two diameters at right angles'to each other, for the purpose'of further stiffening the spring, but in some em- 40 bodiments of the invention the spring might be made of sufficient'stiffness without the ribs I08} The ribs I28 preferably extend downward when the. spring washer I26 is assembled with the tool holder 2| so as to increase thebearing surface against which the end of the driving knuckle 86 engages over the surface which it would engage if the ribs projected upward. Thespringwasher I 20 rests against an'annular shoulder I29 at the base of the counterbore I24 and is clamped in place by a threaded member I30, the end of which engages the upper surface of the spring adjacent its periphery.

The threaded member I30 has its periphery threaded to be received in the threaded bore I24,

, and it also has its threads extending in such a direction that it will be driven home by the driving action of the motor driver. The threaded member I30 is provided with a centrally located aperture I3I, which is preferably non-circular in form and complementary to the shape of the driving knuckle 86. The aperture is slightly 7 larger than the driving knuckle 86 so as to permit parts have very little bearing pressure on each other, they may be constructed of hardened steel and made to fit accurately by lapping them in and theyretain their fit for a long period of time and do not pick up the particles of grindings or grains from the grinding wheel as do the softer. Thus, the guiding surfaces. of the tool holder and pilot do not wearv materially and maybe kept accurate for a long metals used in the priorart.

period of time.

With a slight amount of lubricant on these two hard contacting surfaces the device maybe theresilient. action of the'spring I4 which urges the shaft outward. This spring action eliminates shocks on the grinding wheel whichmight other wise be caused by the unsprung weight of the motor; and the spring I26 in the tool holder has a similar action in preventing such heavy shock to the grindingv wheel that the grinding wheel would break.

Referring to Fig. 1, this is a side elevational view'of the assembly with the driver in the position which it assumes when the operator begins his operations. While the driver is operating'at high speed the operator sways the handle I 32 back and forth through a relatively small arc, movingithe driving motor angularly withrespect to its driving knuckle '86. This results in a different action on the driving wheel 22andetfects a dispersion of the cuttings and constant clean-,-

ing-of the grinding wheel.

non-circular or hexagonal end of the driving knuckle is there shown at an angle with the end plug H6, or at an angle to the axis of the pilot 23 and tool holder 2I. As the hexagonal part 86 rotates there is an axial movement of this hexagonal part, due to the distance between the spring I23fland the successive corners I33, I34, I35, I36 of the hexagonal part. I

, In other words, at the instant shown, the corner I36 of the drivingknuckle 86 is in engagement with the spring I26, but as the corner I36 rotates downward toward the position where it Will engage the spring I25 there is an axial movement of the drive shaft downward which is'equal to the distance X shown in Fig. 3. 1 a

' Thus, the use of a non-circular driving member disposed at an angle causes thedrive shaft to give a number of downward impulses to the tool holder, the shock of which is, however, partially ab sorbed by the spring I26, and the shockof the motor weight is not transmitted to the tool holder on accountof the fact that the motor is spring.

supported by means of the spring I4.

This vertical impulse action of the drive shaft on the tool holder produces variations in pressure on the grinding wheel-22 as it grinds the seat 24. Furthermore, the pilot stem 23 is a relatively slender and resilient metal member, and the tilt of the drive shaft 48 and driving knuckle 86 gives these periodic impulses a lateral component which tends to cause the tool holder to vibrate with the pilot stem ina lateral'direction,

somewhat like the vibration of a tuning fork.

. Thus the toolholder is subjected to vertical imccannot izbe. certainly .determined, but it 153 .13051- 5 utivelyknown that the swaying :actioni .oi the mottorrjdriverwith the structure ,of1the'pi1ot,:.tool hol'derian'd shock absorbing springs asfldescribed -results in: :a) complete-"dispersion of i the cuttings -while'the 'gi'irzder is operating, and the grinder :is

capable of producing-a; substantially "mirrorQIike valve surface without any grooves or other irregularities and without producing any 1 notice- =able= wear.=on=-the grinding stone. :All-o'f this-may 'be done at '-a -veryhigh speed, thei'high speed "aiding' the smooth 'action "ofthe-gririder=an d-subfleeting the-grinder toihig-h 'i'requency vibration as well as increasing 'thespeedzatwhich the work -'may-be"done. y W

-Ass1-iming-=a -rotary speed of 13,000 P. M using a hexagonal driving kn-uckle, eachcornerof the grinding knuckle -wil1- pro'duce one complete vertical "escillation or variation in pressureoor lateral oscillation on the 1 pilot because the rm- -pulse whichis given to i the tool 'holder by the cornersof the-hexagonal driving knuck-le" takes place "between the flat'porti-on of the driving knuckle and 'each' corner. The frequency of vibration wouldythereforef'be six times 131000301 "inthe range "of 78,000 complete vibrations per "minute.

' It should also be pointed "out thatthe grinder is preferably supplied" with a-rough' or c'oa-rse stone and with a relatively 'fine finishing stone, in-order to secure thei-bestpossiblefi-nish, but a mirror like surface of extremelysmooth and uniform characteristics cambeproduced on-ayalve seat with the present grinder, even by the useof arelativelycoarse stone.

"The'modez of operation of'the present apparatusvan'd the method of reconstructing valve-seats according'to theipresent invention"may?be:described asjfollows: I

"The grinding stone is firstr'dressed to anaccu- I rate' frusto-conical surfaceof' predeterminedangularity, determined by the angularity of the valve seat in question. "The" valvestem pilot {is then fixedly secured in the valvestem guideby shoving'the tapered portion of ."the pilot fdowvn into the guide until the pilot is fixed therein. The

tool holder bearing the grinding stone is then sli'dably and rotatably mounted onthe guide, and the motor driver is'heId above with itsdriving "knuckle, having the! non-circular end in the non-circular socket or the'tool holder.

It is not necessary to exert any pressure on the motor driver, but, on the contrary, a very light pressure is desirable, such as that exerted by the weight of the motor itself. The motor may then be turned on and the grinding stone and tool holder rotated at a high speed of approximately 13,000 E. P. M., While the handle of the motor is oscillated back and forth through a small arc of from fifteen to thirty degrees, more or less, depending upon the range of motion permitted by the clearance between the non-circular socket and the non-circular end of the drive shaft. I

The high frequency vibration results in the dispersion of the cuttings and produces a mirrorlike seat without any substantial effect on the grinding stone.

The method of grinding valve seats may be described as rotating a grinding stone in full contact with :a valve seat, while subjecting the grinding stone to periodic vibrations, varying the 1pressureiandtoriareazofccomtact oftthe StOnGLIbY -ianglilar :osciilations. ofttheistonerinisuchrmanner ':as:tooconstantlyiidispersetthe,cuttings, ia ndipre- -vents-cloggin'gworiloading ofathe stone; i. i

'L'Ituwill' thus 'be observedlthat I haveiinvented;

an improvd valve seat rgrinder, the s tr-ucture' of which is considerably :si-mplified over the de- 'requiremany-complicated driving mechanism for "both i rotating and revolving -the stone, sand yet i thedevice ifeets: a dispersion of i the "cuttings, 'con'stant cleaning crane stone, 1 and produces a -mirror lilce i inishpn thevalve seat,width-could not be done with the "11111 contact stones- 0f the prio'reart. I i 1 The spring action of the I resiliently mounted, drive shait'preventsshoeks tdthe stone by means -'-o*f the --mass -'o'f 'the motor and the periodid impulses tr ansmittdd to* the tool holder and stone vices of -the pnior'aart, inasmuchnas it does'g'not '"by' means of the-resiiientiy "mounted drive "shaft 5:20

produces avibratory -actionof the-stoney-which vf nightly lifts" the -"stone from its seat periodical-1y -as ithe grinding progresses *and"perm-its the-cut- 7 tings-to be *th'rowi'i o'ff "-centrif ugally, this'action being also guided by theiair-currents-causedby the-rotatingstone. H g k I "The 7 present grinding apparatus" is so simple that it may be manufactured ata 'much lower 'cost than the "complicated devices of the "prior art, particularly the eccentric type of grinders, "randthis -gfinder-may:bemanufactured at a cost which-is within the-"meansof-a vastnum-ber of purchasers. i

The j present "angular attachment prov-ides a means whereby any ordinary driving motor-may :be'providedwitlra drive shaftremovably' secured thereto and --havi-ng -proper characteristics for -use in *practi's-ing 'thepresent method. *The an- "gular *att'achmentmay, "of *course, also be used withf the regular driver "for-"access to the valve -seats"which aredisposed inrelatively inaccessible positions under the dash, and the scQpe-ofuse- 'fulness of the grinder is "greatly -eXte-nded b 'liavi-ng thus described my mvention} what" I 7 claim as new anddesire to secure by Letters Patent of the'United-wstates isz I v 1. In a valve seat grinding apparatus, the

combination of a pilot .stem adapted to be fixedly secured in centered position in a valve stem guide, with a grinding wheel holder slidably and rotatably mounted on said pilot, a motor driver, adapted to rotate said grinding wheel holder, a grinding wheel and an angular attachment providing an operative connection between said motor driver and said grinding wheel holder whereby said grinding wheel holder may be rotatedin an upright position, with the motor driver disposed at an angle, said angular attachment having a drive shaft resiliently mounted in said angular attachment for reciprocating movement against the compression of a spring resiliently to support the weight of the motor.

2. In an angular attachment for grinding machine drivers, a housing having means for attachthe end of the drive shaft, aseccnd driven shaft rotatably and reciprocablyv mounted in-said angular attachment, and ,resilient means for'urging said driven shaft Outward with respect to said angular attachment whereby said angular attachment is resiliently supported when its weight rests upon said driven shaft.

3. In an angular attachment for grinding machine drivers, a housing having means for attaching said housing to the'housing of a motor driver, adriven shaft fixedly mounted in said attachment housing and having .a socket for receiving the end of thedriver shaft, a second driven shaft rotatably and reciprocably mounted in said angular attachment, resilient means for I urging said drivenshaft outward with respect to said angular attachment-whereby said angular attachment is resiliently supported when its weight rests upon said driven shaft, and operative mechanical connections between said' I second driven shaft comprising a pair of pinions carried by said shafts intermeshing each other and having their teeth spaced from the bases of the tooth spaces to permit axial movement of said second driven shaft.

4. A driving device for valve seat grinders comprising a motor driver having a projecting drive shaft with a hub surrounding said drive shaft, an attachment comprising a tubular housing adapted to be clamped to said hub, said tubularhous- 7 ing having a driven shaft with a socket for receiving said drive shaft, and: a second shaft disposed in said tubular housing at an angle to the first-mentioned driven shaft whereby the motor may be disposed at an angle to the secon'd shaft to prevent interference with the dash of a motor vehicle in grinding the valve seats adjacent thereto, said second shaft having an anti-friction bearing slidablymounted in said tubular housing, and resilient means for urging said second shaft outward with respect-to said tubular housing.

5. An angular attachment for motor drivers comprising a tubular housing having twocylindrical parts, the axes of which are at an angle to each other, a shaft mounted in each of said cylindrical parts for rotary movement, one of said shafts being mounted also for reciprocatory movement along its axis,'pinions carried by the adjacent endsof said shafts, said pinions intermeshing and having sufficient clearance between the teeth of one pinion and the base of the tooth spaces of the other pinion to'permit reciprocatory movement of one of said shafts.

6.. An angular attachment for motor'drivers comprising a tubular housing having two cylindrical parts, the axes of whichare at an angle to each other, a shaft mounted in each of said cylindrical parts for rotary movement, onefof": said shafts being mounted also for reciprocatory movement along its axis, pinions carriedby the adjacent ends of said shafts, said pinions intermeshing and having sufiicient clearance between the teeth of one pinion and the'base' of the tooth spaces of the other pinion to permit reciprocatory movement of one of saidshaftsjan antlfriction bearing for, said reciprocably .mounted shaft, and resilient means interposed between said tubular housing and said anti-friction bear- 2 ing for urging said reciprocably mounted shaft outward with respect to said housing.

7. An angular attachment for motor, drivers comprising a tubular housing having two cylindrical parts, the axes of which are at an angle I to each other, a shaft mounted in each of said comprising a tempered steel washer having a,

plurality of resilient metal tongues. bent out of the body of said washer.

8. In a valve seat grinding apparatus, the combination of a pilot stem adapted to be fixedly secured in centered position in a valve stem guide with a grinding wheel holder slidably and rotatably mounted on said pilot, a grinding wheel carried by said holder, a motor driver adapted to drive said grinding wheel holder, said motor driver having a drive shaft, and an auxiliary drive shaft disposed at an angle to said firstmentioned drive shaft, resilient means interposed between said auxiliary shaft and said tool holder to absorb shocks, and a non-circular connecting device between said wheel holder and said auxiliary shaft adapted to place said holderand wheel in a state of vibration on said pilot stem during its rotation.

FRANS O. ALBERTSON.

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