US2042759A - Valve seat grinding machine - Google Patents

Description

June 2, I1936.

F. O. ALBERTSON VALVE SEAT GRINDING MACHINE Original Filed De'o. 25, 1932 3 Sheets-Sheet l June 2, 1936. F. o. ALBERTSCJNr 2,042,759

VALVE SEAT GRINDING MACHINE Original Filed Dec. 23. 1932 5 Sheets-Sheet 2 June 2, 1936- F. o. ALBERTsoN VALVE SEAT GRINDING MACHINE Original Filed Dec. 23, 1932 3 Sheets-Sheet 5 "..IIIIIII QIIIIIIII El! Patented June '2., 1936 VALVE SEAT GBINDING MACHINE Frans O. Albertson,A Sioux City, Iowa, assignor to Albertson & Company, Inc., Sioux City, Iowa,

a corporation o! Iowa Application December 23, 1932, Serial No. 648,564

Renewed May 11, 1935 11 Claims.

The present invention relates to valve seat grinding machines particularly adapted for use in the forming, reconstruction or repair of the valve seats of internal combustion engines.

5 However, the methods and apparatus arevof general application and may be utilized for valves of dierent kinds, and I do not wish to be limited in the use of my invention to any particular type of valve.

The grinding machines of the prior art either have the grinding-stone brought into engagement with the entire periphery of the valve seat at one time or they include complicated devices for both rotating the grinding wheel and revolving lli the grinding wheel in an orbit to engage allparts of thevalve seat with a lgrinding wheel which is of a smaller diameter. lA full seat contact between the grinding wheel andthe valve seat -results in the clogging or loading of the wheel Q with the material which is ground from the seat, and this causes a change of the contour of the stone and results in the grooving of the valve seat.

The grinding stones are also apt to be broken when the stone engages the entire periphery at once, and serious injury may result when the. grinding stone, which is rotating at a high rate of speed, is broken and its pieces are thrown ofi' from the machine.

The devices of the prior art, which are adapted to revolve the grinding stone in an orbit,as well as rotate the grinding stone, are very complicated and expensive, and such devices cannot be brought within the means of ordinary garage owners on account of the expensive mechanism and machine -work required to produce the complicated grinding tool.

One of the objects of the invention is the prol vision of an improved method of reconstructing4 valve seats by means of which the extremely hard seats of stellite, tungsten steel, or other hardened alloys can be ground quickly and 1mii'ormly to produce a nished seat, with a minimum amount of labor. The tendency in construction of valve seats for internal combustion engines is toward the use of seats of harder material, which cannot be satisfactorily worked by means of ordinary metal cutting tools.

Another object of the invention is the provision of an improved method and apparatus which is vadapted to produce a finished valve seat at predetermined angularity, and which is adapted to eliminate the hand-lapping operation which is found necessary when the grinding machines of the prior art are used.

Another object of the invention is the provision of an improved grinding tool by means of which full seat contact is avoided so as to eliminate the clogging and loading of the grinding wheelv or grooving of the seat and to provide a grinding tool which is self-cleaning.

Another object of the invention is the-,provision of an improved grinding tool which is adapted to disperse the cuttings continuously and prevent loading of the wheel or lllng of the Y interstices between the abrasive particles of the l0 v wheel at the surface with the cuttings, the outtings being dispersed by the current of air caused by the close proximity of the surface of the abrasive wheel to the valve seat at the points where the wheel does not actually engage the seat.

Another object of the invention is the provision of an improved method and apparatus for reconstruction of valve seats by means of which the relatively light stone pressure and the random initial engagement of the stone are adapted to. produce a nished seat, the quality of which is commensurate with the quality of a seat secured by a hand-lappingy operation.

Another object of the invention is the provision of an improved grinding tool, including a spring for lifting the tool and enabling the operator to use a light stone pressure by means of which the friction on the spring and wheel hub is eliminated so as to prevent the heating of the spring and the drawing of the temper of the spring and to prevent damage to the stone by the heat which `melts the sulphur and-loosens the'stone from its mounting on the hub.

Another object of the invention is the provision of an improved tool holder, an improved dressing tool, an improved motor driver, an improved grinding stone structure, and an improved grinding tool assembly, all of which are simple in construction, sturdy, and capable of lmanufacture at a low cost, so that the invention may be 40 brought within the means of a vast number of users who may practice the methods disclosed therein with prot to themselves and benecial results to the valves upon which the tools are used.

Another object of the invention is the provision of an improved tool assembly, including a motor driver and a universal connection between the motor driver and a grinding wheel, including means for eliminating the shocks on the grinding wheel which are caused by the. introduction of the universal joint in the drive between the motor and wheel so that the present device is adapted to Aoperate more smoothly and uniformly than any oi the devices of the prior art to eect a smooth grinding or finishing action on which would be caused by the particular structure and arrangement of the grinding tool without such compensation. Other objects and advantages of the invention will be apparentfrom the following description and from the accompanying drawings, in which similar characters of reference indicate lsimilar parts throughout the several views.

Referring to the drawings, o which there ar three sheets, Y

Fig. l is a side elevational view of the grinding apparatus with the valve and valve stem guide in vertical section on a. plane passing through the axis ci the guide, the assembly including the motor driver, tool holder, grinding wheel and pilt; l

Fig. 2 is an elevational view of the motor driver in partial section on a vertical piane passing through the anis of the armature shaft and drive shalt, showing the mechanism oi the Y during the grinding -ivheel and the valve seat;

driver;

Fig. 3 is a full sized sectional view oi the tool holder and grinding wheel and pilot applied to the valve oi' an internal combustion engine, the section being taken on a vertical plane passing through the axis of the valve stein guide, with thepilot in elevation;

Fla. d is a iragnientary view similar to Fig.' 3, showing an elevational viev ci the grinding wheel, 'with the parte in the proper position lor grinding, and showing the angular relation lietween the frusta-conical surface on the grinding Fig. E is a iragnientarg,v vertical elevational view of the motor driver, tool holder and dressing tool, showing the complete assembly used in the dressing operation;

d is a fragmentary elevational view ol the grinding wise-ei, tool holder, pilot and valve seat operation, with a diagram to show the angular relations between the position of the grinding wheel during the grinding operation and the dressing operation. l

The present 'application relates particularly to the novel elements of the valve seat grinding apparatus, and another cci-pending application, Serial No. 643,584, led November 2l, i932, relates to the method of grinding valve seats.

Referring to Fig. l, the complete assembly ol grinding apparatus preferably includes a motor E driver 2li, a tool holder di, a grinding wheel and a pilot stem 23.

The'appsratusis illustrated in connectionwith a valve seat consisting of a hardened metal ring 2d, which has heen fixedly secured in the bloei?. .2d of an internal combustion "engine, which is provided with a valve stem guided@ The pilot 23 is of the type having a lower cvlin drical part 2l which :dts the substantially cylindrlcal part of the valve stem guide 2e very closely, within one one-thousandth of an inch, for the purpose of centering the pilot 28 in the guide.

The pilot is also provided with a very gradually tapered wedging portion 2@ which extends into the upper part of the valve stem guide 2d and may be iixedly wedged in the guide h y'merely shoving the pilot downward. The taper is prelerably about twenty-three thousandths of an inch per foot, and constitutes the sole means'or securing the pilot in place.

Any other type oi pilot which is capable ol being accurately centered in the valverstem guide 26 and xedly secured therein may be used, such as the expanding pilot covered hvmy prior Patent No. 1,902,207, issued March 21, i933.

Referring to Fig. 2, the electric motor driver is shown in detail in this gure. The motor driver preferably consists of an electricmotor of the series4 wound type, having a casing 23 within which is supported, by a plurality of screw bolts 36, the iixed field Bl. The upper end ci the casing is closed by a cover plate 32 which slidably supports a pair ci brushes 33, and which is provided with a socket Sil for receiving the selialigning ball bearing races 35, 3S and balls 3l.

The ball hearings 35-3? are provided with a supply of hard luhricant which is kept in place .by an oil seal 3B, having a packing 3Q engaging the inner race i3d.

The armature is xediy mounted on an armature shaft d@ and provided with appropriate A di, and halls dd with an oil seal dll having a pack- Y ing d. l

The armature has an enlarged portion il which supports the hub dd of a fan dd, and the casing is provided with ventilation apertures 5d adjacent the periphery of the ian.

.llt the opposite end, the cover 3 2 is` provided with ventilation apertures 'ille motor casing E3 includes a partition d2, having a loore 55S for receiving the ball bearings li--dd and having another bore dei for receiving e second hall hearing comprising the races and halls di. The ezible oil'sealing member till oi cup shape ents the egress ci oil from the gear housing onenigheiil@ into the motor through the here d. l

The end plate te of the motor supports a gear housing d@ which is provided with an o'set hess di having a here d?. for receiving a sleeve d3.

Sleeve dll has an inwardly extending iiange ei forminga socket @d for the self-aligning inailv hearing, comprising the races'ed, el' and calls 63;

An oil seal is preferably provided for preventing leakage of lubricant from the lower end of the gear housing di? out ci the oli seal member, corn-l having a cylindrical ange il, and a radial danseV l2, is secured in theennular member es, and the radial danse is clamped in place by an annular ring i3.

ii garter .spring-ld extends about the cylindrical ange il and urges it intoengagement with an enlarged cylindrical portionld on the drive shaft T6. The garter spring is conned in place by a second angular ring il and endless coil spring about. the cylindrical leather ange which tends to seal the space between the shaft and the housing o-agalnst the egress of lubricant.

The armature shaft lo projects out oi the motorinto the chamber BS of gear housing ed, where it is preferably provided with a helicoidal pinion l@ which meshes with a similar helicoidal gear l carried by drive shaft 16;

' The gear ratio is particularly adapted to drive ,'A'proper grinding action with grinding wheels of this type, the wheel must have a minimum speedk of 3,500 linear feet per minute, and a maximum of 6,000 linear feet per minute, at the grinding surface. The electric motor, for example, may have. a speed of 3,600 4revolutions perminute, and in order to provide for grinding' wheels of the various predetermined sizes, I prefer to provide al 6,000 R. P. M. driver and a 9,000 R. P. M. driver,

the latter being used for smaller wheels.

The gears 18, 19 are adapted to step upthe speed of the drive shaft 16 over that of the motor shaft 40 to a speed vappropriate for carrying out the present methods.

The drive shaft 16 is also preferably formed with an annular shoulder and with a reduced threaded portion 8| for receiving the connection sleeve 82.

.The sleeve 82 has a threaded bore 83 for re ceiving the reduced end 8| of the drive shaft, and the sleeve 4isprovided with a frusto-conical lor tapered bore 84 for receiving the driven end of the tool holder shaft, which is of complementary shape.

Sleeve 82 is alsoprovided with a pair of grooves or slots 85 extending longitudinally into the end of the sleeve and locatedv diametrically opposite to each other, having the grooves 65 substantially semi-circular at 86 to receive the rounded pin 81 carried by the tapered end 88 of the tool holder shaft. j

The motor driver 20'is provided at its upper end with a metal handle 89 having apertures 90,-

9|, below the grip for receiving the ngers, and the handle is provided with a switch actuating member 92 pivotally mounted at 93.

The handle 89 contains a snap switch actuated by the lever 92, andis provided with apertures 94 for passing the-conductors leading to the switch 95 and leading out of the rubber covered conductor cable 96.

The tubular -rubber member or hose 91 is securedl between the halves of the handle 89 by means of a metal clamping kring 98 which clamps the hose against the cable 98, the ring being disposed in a groove in the handle and secured in place in the handle when the halves of the handle are secured together by the bolts 99. The tubular rubber member 91 prevents a breakin the cable where the cable emerges from the handle,V and also serves to anchor the cable by the clamping engagement of the rubber of the tube against the cable 96 without injuring the cable.

Referring to Fig. 3, this is a vertical sectional view through the tool holder. The pilot 28 is provided with a. substantially cylindrical upper-.part |80, which may be provided with an aperture |06 to receive a pin for manipulating the pilot and shoving it in or pulling it out of wedging engagement with the guide 26.

The tool holder 2| is also provided with a. tubular metal member |08 having an elongated and accurately machined bore |188 for slidably and rotatably receiving l the cylindrical portion |100 of the pilot 88.

The tubular member |02 ls preferably provided with4 the reduced end portions 90d, |05, each of which is slightly tapered to effect a close frictional fit with the inner race rings |88, itil of the self-aligning ball bearings. The ball bearings also comprise the balls |08, |89, and the outer race rings H0, III. Each of the outer race vrings is preferably spun over at one end and at the inner corner H2 to secure an oil seal ring H3 to the bearing. Appropriate packings HI prevent the lubricant from leaking out of the bearings beyond the oil seal H3. f

Metal plates H5, H6 slidably mounted on the tubular member |02 are located below. the upper ball bearing and above the lower ball bearing, to confine the lubricant between the races. As lubricant is not required in the annular space H1, a spacer sleeve H8 is located in the tool holder casing H9 between the plates H5, H6l to hold the plates in proper position against the ball bearings.

The tool holder casing H9 comprises a tubular metal member, such as a steel member, which is provided with a cylindrical bore |20 adapted to receive the outer races l0, H| and the spacer sleeve l I8.

The lower end of the tool holder casing H9 is provided with an annular' inwardly extending flange |2| forming an annular shoulder |22 against which the lower ball bearing rests, and the' lower end of the tool holder casing H9 is provided with a reduced tubular boss |23 for supporting a grinding wheel. The tubular boss |23 has a bore |24 of suillcient size to provide a clearance between the walls of the bore |24 and the tapered pilot 23, since the tool holder is to be guided on the pilot by the sleeve |02 and the ball bearings at each end of the sleeve.

The tubular boss |23 is provided with threads 25 'for receiving the threads on the inside of a metal hub |28 which supports the grinding Y wheel |21 of carborundum'or other solid abrasive i material.

The grinding Wheels may comprise either rough stones for `cutting or relatively smooth stones for finishing work. In some cases, a single stone of 'suitable quality and texture may be suitably dressed to accomplish both results, the rough dressing being used for cutting, and the smooth dressing for finishing.

The lower end of the tool holder 2| is provided witha flat annular surface |28 which extends at right angles tothe axis of the tool holder, and it is also provided with a cylindrical surface |29. serving as a guide for receiving the cylindrical flange |30 on a collar |3I.

This collar will be called the dress-grind collar, and its function and structure will be described in detailhereinafter. The collar comprises the cylindrical flange |30 slidably fitting upon a cylindrical part |29 of the tool holder body l I9, and the collar comprises an end plate |32 which tapers in thickness from the left side toward the' right, as shown in Fig. 3. The endplate |32 has an enlarged bore |33 whichmay be threaded so that the dress-grind collar can be threaded over the threads |25, but it is loosely supported at the unthreaded part |36 between the threads |25 and the at end |28 of the tool holder. This arrangement permits the convenient assembly of the collar and the removal of the collar, and it also permits `the collar to take `its proper position on the end of the-tool holder, but the collar does not fall off the tool holder due to the threads |25, and the parts of the tool holder are thus permanentl;r assembled together in such manner that no part is apt to be lost.

The grinding wheel |21 comprises the metal hub |26, previously described, and `the grinding wheel body of abrasive material, which is prefsurface i3?. The bottom 38 oi the grinding wheel may be dat or take any appropriate shape.

The cylindrical surface 36 of the grinding wheel is merely present on account of a desire to make the grinding wheel o sucient thickness so that it may be dressed and used over again for a l longer period of time until the stone becomes too thin. .es the stone is dressed and used up, the length of the cylindrical surface i315 will diminish, and the stone will become thinner inv a vertical direction.

On the small stones it is unnecessary to provide a guard, as the speed at which the stones are rotated is not suicient to cause any danger, but, if desired, a guard may be provided on all stones, and particularly upon the stones of larger diameter. s

The guard comprises a stamped steel cup having a dat end portion 39 and having a downwardly extending cylindrical border flange itil encasing the end and a part of the periphery of the stone. The guard may be secured to the hub i2@ by spinning over the upper edge of the hub outside the body of the guard.

A ber washer tdi is preferably interposed between the "dress-grind collar @3l and the end of the tool holder so as to facilitate the unscrewlng of the grinding wheel from the tool holder,

as the metal surfaces otherwise become screwed together so tightly that diculty is encountered in tafng the grinding wheel ofi again.

The complete assembly preerably includes a helical coil spring 52 which is interposed heu tween the upper end or" ,the valve stem` guide ldd and the lower end of the tool holder.

it was found the friction oi the tubular boss EEE against the coil spring ll at the high rates of sneed used was so great as to heat the spring and drager temper from the spring and also melt the sulphur in the grinding wheel. in order to prevent friction, the tool holder is preferably provided with a thrust sleeve ldd having a bore of sucient size to receive the 'cylindrical part of the pilot, and having an annular ange lf's engaging the end lill ci the guide sleeve The thrust sleeve ldd is prefierably split longitudinally to permit it to be sprung together, and the flange idd is sumciently narrow so that when the 4split end is sprung together it will pass through 'the bore ld. The flange ltd, however', retains the sleeve in the bore vltd when the spring is removed. VThe thrust sleeve ldd has a clearance with the bore it in the tubular boss itt, and the thrust sleeve extends outward beyond the grinding wheel into engagement with a sheet metal cup shaped niember idd.

The cup shaped member ldd provides a seat for the upper end o the spring itt. Springs of various length should be used, depending upon the distance from the end Edil of the valve stern guide to the valve seat ldd. For instance, the

' top of the spring should be about three-fourths to one inch above the valve seat when the tool Vholder is removed, to provide sulcient compression for lifting the grinding wheel c" the seat.

Several lifting springs or different lengths are sleeve H32 is slidably mounted upon the pilot stem `and* could rotate, but. the friction between the guide sleeve M2 and the pilotis greater than the Vone side of the collar bears the notation dress ceiving the reduced threadedend it? of the ball and the spring when the thrust sleeve IM is ut- 5 lized. The heating ofthe spring is thereby avoided and the temper of the 'spring is not drawn.

Referring to the dress-grind collar` lill, and referring to Figs. 4 and 5, it will be noted that lll on the cylindrical ange im, while the other side of the collar bears the notation grind, and the cylindrical casing lle of the 'tool holder has a mark and the indicia zero. This indicia is used for setting the collar for the dressing or grinding l5 operations respectively and the theory and operationoi these elements will be described in detail hereinafter.

it should also be noted that the threads 32d are suiiciently loose with respect to the hub it so that the position of the grinding 1vheel l2? is determined by the tapered thickness of the body it of the dress-grind collar itl; that is, the plate l 32 being thicker at one side than the other, the grinding wheel ll' engages the plate H22 and 25 is secured against the plate by' the threads 25 in a tilted position, so that the grinding wheel engages the seat Md at one side, as shown in Fig. 3, but only comes into close proximity to the seat 1 at the other side of the grinding wheel.

The looseness oi the threads E permits this tilting of the grinding wheel on the tool holder.

The upper end oi the tool lholder body lid is provided with .threads it@ which may be right hand threads, and the tool holder cap lei may be provided with threads 952 in a left hand direction. Y

Connecting sleeve i523 is provided with complementary threads and threaded into the casing is and the cap itl. Connecting sleeve it is pron 40 vided with an inwardly extending collar flange Het; forming a seat for a relatively heavy coil spring 855. At its other end the coil spring ldd is seated against a dat steel plate itt, slidably mounted in a bore it? in a universal joint sleeve ist.' The cap loi comprises e. cylindrical inem ber having an inwardly extending annular ange its provided with a bore it@ having a curved surface for engagement with the ball lei. The cap is also adapted to receive the universal joint 5G sleeve 58, which comprises a hardened steel tubular member, having four axially extending slots it? located ninety degrees apart.

The lower end of the universal `loint sleeve l5@ i is provided with axially extending slots E63 for 55 receiving the axially projecting ridges itil carried by the connecting sleeve E53. Slots and ridges its, ltd provide a driving connection between the sleeves 58 and 853. A driving connecnon is provides between the ban est and the 6G,

sleeve 53 by four transversely outwardly projecting vcylindrical steel pins idd engaging in the slots 562. The slots It? are of sucient length so that the pins U may move upward and downward in 65 the slots as the ball itl rotates in the socket provided in the end of the cap ll. Ball itl is preferably provided `with a threaded bore ld for reshank. The ball shank is tapered'at @d for reception in the drive sleeve oi the motor driver, and is provided with a transverse pin 8l to be received in the groove d5 of the motor drive shaft.

The motor driver, therefore, rotates the shank l y races of the ball bearings, do not rotate, and the self-aligning ball bearings provide a very smooth rotating action for the grinding wheel, resulting in a uniform grinding action on all parts of the periphery of the valve seatv |49.

As itis practically impossible to hold the motor driver 20 axially above the tool holder 2|, the universal joint provided by the ball |6|, cap |5I, and sleeve |58 permits the driving of the tool holder by the motor driver, although the motor driver is not held in direct axialv relation to the tool holder. During the driving, the tool holder is guided by the pilot 23, irrespective of the position of the motor'. However, it is found that direct mechanical shocks are transmitted to the grinding wheel 22 (Fig. 1) from the motor 20 on account of the action of the universal joint, unless some form of resiient connection is used, and the compression spring |55 in the universal joint eliminates the shock which would otherwise be caused by the universal joint.

The use of this spring gives a smooth drive for the grinding wheel and tool holder and facilitates the grinding and finishing of the valves with greater uniformity and a better nish. The shocks ycaused by the use of the universal joint are not transmitted to the grinding wheel when the spring |55 is utilized, but are absorbed by the spring.

f Referring to Fig. 4, this shows the tool holder and grinding wheel in the grinding position, and the dress-grind collar I3| has been turned so that the word grind appears under the mark zero.

The right side of the grinding wheel is accomplishing the grindingA action, as evidenced by the dark mark |68 on the frusto-conical surface of Vthe grinding wheel, and the grinding wheel 22 does not come into contact with thevalve seat at the side |69, as shown by the space between the wheel and the seat at |69, this clearance being, however,.exaggerated for the purpose of illustration. The grinding wheel is, however, sufliciently close to the seat so that the irregular abrasive formations on the wheel cause currents of air which blow off the grindings, and the wheel is self-cleaning. This self-cleaning action enables the grinding of a more nished seat and a more uniform grinding action, because the seat is actually ground toconform to the surface of the grinding wheel and is not marred by the presence of grindings b etween the wheel and the seat.

The present grinding wheel is preferably dressed apart from the valve seat |49 so that the abrasive which is'dressed 0E the wheel does not fall on the valve seat. For this purpose I prefer to provide a dressing tool, a part of which is shown in elevation in Fig.,5. The dressing tool comprises a supporting base |10 having a at bottom upon ,which the dressing tool stands, and the base slidably supports upon a guide lever it a plunger 202carrying an adjustable-screw 220 which supports a diamond or other hard cutting Imember 22|. The guide |82 isl mounted for pivotal movement with respect to the base |10, and thus the plunger 202 may be made to move along the element of a' cone of any angularity. The base |10 supports a dressing pilot '224, the upper portion of which is*v of substantially the same shape and size as the upper portion ofthe pilot 23. I

At its lower end the pilot 224 is provided with an enlarged cylindrical portion 225 and with a reduced threaded portion226 which is threaded into the bore 223. The cylindrical portion 225 is adapted to slidably receive a tubu- 5 lar supporting member. The upper end is provided with an inwardly extending radial ange 228 and a bore 229. T'he bore 229 is adapted to receive the dressing pilot 224, and the tubular member 221 is adjustably mounted on the cylindrical part 225 to support the grinding wheel .22 at the desired height.

For this purpose, the sleeve 221 is provided with a spiral slot 230 which engages the compiementary end 23| of a threaded screw bolt 232 having a knurled head 233. The screw bolt 232 is adjustably supported in a threaded bore 234 in a standard 235, the lower reduced end 236 of which is mounted in a bore 231. The standard 235 is secured in place by a set screw 238. A washer 239 is interposed between the hub of the grinding wheel and the end 228 of the supporting sleeve 221 to positively prevent engagement of the grinding wheel with the sleeve 221 and permit the grinding wheel to rotate more 25 freely. This washer should be oiled frequently so as to permit the grinding Wheel to rotate freely during the dressing operation.

An understanding of the mode of dressing the grinding wheel is necessary to an understanding of the operation of the grinding wheel, and the manipulation of the dressing tool is illustrated in Figs. 5 and 6. The supporting sleeve 221 is lifted manually by rotating the sleeve, and secured in place by means of the set screw' 233 engaging in spiral slot 230, with the grinding wheel at the proper height. The grinding wheel 22 is, of course, mounted on the tool holder 2| and adapted to rotate with the tool holder on the dressing pilot 224.

The motor driver 20 is again used 'to drive the rgrinding wheel at a proper speed during the Ais pushed downward the diamond 22| will engage 45 'the grinding wheel 22 and take a very light cut oi the surface of the grinding wheel. In order to provide a surface on the, grinding wheel which. is desirable for fast cutting, the plunger 202 should4 be pushed down rapidly, but in order -to 50 provide a relatively smooth nish on the grinding wheel for iinishing, the plunger 202 should be pushed down very slowly while the grinding wheel is rotated by the motor driver 20.

Referring to Figs. 4 and 5, these figures illus- 55 trate the action of the grinding wheel during the grinding and dressing operations respectively. It has already been explained that the grinding wheel may be supported on the tool holder 2|, with its frusto-conical surfaces slightly tilted 60 with respect to the axis of the tool holder, which, of course, also corresponds to the axis of the When the grinding wheel. .22 is placed upon the tool holder 2| for a dressing operation, the dress-grind ,collar should be turned to the position of Fig. 5, and the grinding wheel 22 threaded home upon the tubular lug |23. The dressing voperation is then carried out, as previously dewith respect to the of the tool holder 2l.'v the surface l3l' which-is produced by the use of the diamond. dressing tool is accurately frustoconical because the diamond dressing tool is moved along an element of a. cone, the axis of which is the axis of the dressing pilot, and the body of the stone is rotated about the axis of the dressing pilot.

rEhe surface i3? is, therefore, accurately frusto-conical, and whether it is relatively rough for fast cutting or relatively smooth for nishing work, will depend upon the manipulation oi the dressing` plunger. When the dressing plunger is moved down fast during the rotation of the grinding wheel, it may be assumed that the diamond will cut oi a part of the grinding wheel surface corresponding to a spiral path, and it vmight leave parts of the abrasive surface between this spiral path. When the diamond supporting plunger is pushed down slowly during the fest rotation of the grinding wheel, and care is taken that the diamond strikes every part' of the. grinding surface of the grinding wheel.

this sin'face will be dressed to a substantially I thick part 24E of the dress-grind collar isi is smooth frusto-conical ilnish, as the diamond will have an opportunityto take oi all parts 'o'f the abrasive surface which it can touch.

When the wheel is tobe used for grinding, the grinding wheel 22 and tool holder 2i are removed from the dressing tool, and the dress-grind collar i3! is loosened by turning-the grinding wheel 22 in a counterclockwise direction and loosening its hub B26 on the threads H25. The dress-grind Vcollar is turned one-hundred and eighty degrees from the position of Fig. 5 to that of Fig. d, until the word grind3 is under 'the pointer bearing the indicia zero.

Referring to Fie. 5, it will be observed that the located at the left side, and referring to Fig. d it will be noted that the-thick part 26|] of the dress-grind collar is located at the right side when the stone is in position for grinding.

V In other words, the thickness of the plate between the grinding wheel and the end of 'the tool holder tapers from left to right in Fig. 5 and from right to left in Fig. 4. If the grinding wheel is tilted upward toward the right in Fig. 5, it `will be tilted downward toward the right in Fig. 4. As a result of this, the side of the grinding wheel which is toward ,the right in Fig. 4 comes in contact with the valve seat. but the side |69'l of the grinding wheel in Fig. 4 does not engage the valve seat.

Referring to Fig. 6 the angular relation of the parts is best illustrated by the diagraml shown between the'grinding wheel and the valve. It should be understood that the proportions of the taper on the spacing plate of the "dress-grind preferably made such that the grindingwheel collar may be varied. and I do not wish to limit myself to any particular taper. This taper is engages only at one side over substantially onethird of the grinding periphery of the wheel, and

vte

the taper is preferably such that the other part of the grinding wheel is located in close proximity to the seat so as to effects. cleaning action by virtueY of its proximity and by virtue of theair current vcaused by such proximity. V

For example. in one embodiment of the invention the taper in the spacing plate of the dressgrind collar is such that theangle between the Yuppeeand lower surfaces of the .dress-grind collar diverses two-tenths of e. degree from the pareilel. This divergence-is exaggerated in the www i Vdiagraml shown yin Fig. 6.." The grinding y'wheel would,l therefore, be tilted' two-tenths of adegree toward the left in Fig.l 5 and two-tenths of a degree toward the right in Fig. 4; the change in tilt of the grinding wheel from the dress posi- 5 tion to the grind position wouldv be the sum of these two angles, or four-tenthscf one degree or approximately one-half degree. y l

In other embodiments of the invention, the tilt may amount to several degrees, but it is preferred to keep the tilt as low as possible in order to keep the non-contacting parts of the grinding wheel in close proximity to the surface of the valve. -The minimum ci' tilt permissible is that which accomplishes a suitable dispersement of the cuttings and self-cleaning of the vgrinding wheel.

-Since the grinding wheel is tilted on the tool holder between the time when the wheel is s: and the wheel is used. for grinding, it will be ob.- served that if the dressing tool had its angularV markings for any particular angle sodisposed that the plunger would move at that angleto the dressing pilot, the angularity of the grinding 'wheel would not be correct when it is later tilted on the tool holder. In other words, if the diamond supporting plunger were accurately held'at forty-live degrees, and the grinding wheel -22- .were tilted a half degree tothe left. in Fig. 5,

' f grees are preferably not located to hold the plunger at exactly forty-live degrees to the dressing 4 pilot. Each of the angular degree markings is located to hold the dressing diamond plunger at a predetermined vangle which will so dress the grinding wheel that the grinding wheel will produce a. nished seat of the predetermined angus larity desired.

The grinding wheel is not dressed at the angularity desired for the seat, but at such an angularity that when'the grinding wheel is Vtilted that element of the grinding wheel which en- "gages the seat |49 at the right side in Fig. 4

located at the angle desired. Y A The dressingltool is thereby adapted to compensate by means of its adjustments and indications fory the tilt which is later accomplished by means of the dress-grind collar in the grinding operation. The fact that this dress-grind" collar also may tilt the grinding wheel in the opposite direction prior to the dressing action does 30 not aect the accuracy of the dressing of the wheel, but merely makes the tilt twice as much 'Y as could otherwise be accomplished, since the wheel is moved from a position where it is tilted toward the left to a position where it is tilted towardtheright.. Y Y' The method ,of finishing valve seats or recon-` structing valve seats may be carried out by the apparatusY described, and is preferably practiced as' follows: 7 A recess is first out in the seatof thevslve in the engine block.the recess being adapted to rcceive e. new valve seat .of tungsten steel, stellite, or some `other alloy' better u V amano 'adapted to withstand the heatand impact to l which valve seats are now subjected. The ring is secured in place by close frictional engagement with the walls of the recess or by spinning over the metal of the engine block above the ring. The toolholder may then be provided -with a rough grinding wheel which is placed upon the tool holder with the dress-grind" collar in the dressing position of Fig. 5.

The tool holder and grinding wheel areplaced upon the dressing pilot and the tool holder is rotated at a high rate of speed within the range specified, while the diamond dressing tool is moved across the face of the grinding wheel in a direction which corresponds to the angle of the valve seat dired, plus or minus the .amount of tilt caused by thefdress-grindVJ collar. If the same stone is to be used for both the .dressing and grinding operations, the diamond is moved quickly across the surface of the grinding wheel to produce a relatively rough and fast cutting wheel. The wheel is thenvloosened from the tool holder. and the dress-grind spacing collar turned onehundred and eighty degrees, after which the wheel is again tightened on the tool holder and, by virtue of the taper of the spacing plate between the grinding wheel and the tool 'holder end, the lwheel has been tilted a predetermined number of degrees equal to the degrees for which the dressing tool is compensated.

The tool holder is then placed upon the pilot,

, which has previously been fixedly secured in the valve stem guide in centered relation, and the l grinding wheel is supported above the valve seat by means of the compression spring. The motor driver isv applied to the upper end of the 'tool holder, and while the motorl is operating at a high rate of speed within the range described the motor and tool holder are pressed down light'- 40 1y until the grinding wheel engages the seat.

j The grinding wheel should not be pressed so hard `that the speed of thewheel and the motor is slowed up. but a very light pressure should be used, and as'the grinding wheel rotates, the tool holder, wheel and motor should be movedup and down frequently in the same manner as that used in lapping in a valve. The grinding wheel will then come into initial engagement -with the seat at dierent points rotatively of the seat, and the random engagement between the grinding wheel and the seat will givea more'uniform action and permit more nished grinding of the seat than a continuous grinding action. The rotation of the grinding wheel tilted with respect to the seat causes only one side of the wheel to grind the seat, and the other si'de of the wheel aids in dispersing the cuttings from the seat and the wheel by virtue of its close proximity to the seat.

The same grinding wheel may then again be dressed to a finished surface and applied to the y seat in the same manner to' produce a finished seat, or a relatively smooth stone may be dressed and used in the same manner to produce a finished seat. The fast cutting or rough grinding wheel need only be used where there is a great deal of material to be cut away from the seat, as, for. example, when a new valve seat ring is used which does not have a frusto-conical seat formed upon it.

In brief, the method of finishing the seat comprises the rotation of a grinding wheel of frustoconical form while passing a dressing element across the frusto-conical surface of the. grinding wheel at an angle which is equal to the rangle tool holder, said oi the seat desired plus or minus-a predetermined angular tilt,' thereby dressing the wheel to -an angularity which does not correspond to that of the seat desired, then tilting the grinding wheel with respect to its axis of rotation and A5 applying the grinding wheel to the seat in such manner that only one side ofthe grinding wheel touches the seat, lthe tilt being the predetermined amount for which compensation has been made in the dressing operation.

It will thus be observed that I have invented an improved method, an improved grinding tool assembly, an improved tool holder, an improved dressing tool, an improved grinding wheel, and other apparatus for the purpose of grinding valve seats of internal combustion engines.

The present grinding apparatus is admirably adapted to handle valve seats of particularly hard alloys and to' produce a finished valve seat Without necessity for .any hand lapping operations. The grinding action of the tilted wheel is very fast and yet smooth and uniform, as the tilting of the wheel effects a dispersion of the cuttings and prevents the loading or clogging of the wheel so that the ground seat corresponds closely to the shape of the accurately dressed grinding wheel.

I'he use'of the spring mounted universal joint prevents the transmission of shocks from y.the universal joint and motor to the grinding wheel, and also makes for a smoother grinding action of the wheel. y

The present resultsare' all'accomplished by means of a very simple type of apparatus, which does not require but a single drive shaft and the 3 valve seat grinder is much more simple than the devices of the prior art, so that it may be brought within the reach of a large number of users.

While I have illustrated a preferred embodiment of my invention, many modifications may 40 be made without departing from the spirit of the invention, and I do not Wish to be limited to the precise details of construction set forth, but desire to avail myself of all changes within the scopeof the appended claims. t

Having thus described my invention, what` I claim as new and desire to secure by Letters Patent of the United States, is:

1. In a valve grinding apparatus, the combination of a valve stem pilot with a tool holder Cal 'adapted to be slidably and rotatably mounted on said pilot and a grinding wheel carried by said tool holder, said grinding wheel being tilted with s respect to the axis of rotation of said tool holder whereby said grinding wheel engages the work only at one side, a driving shaft for said tool holder, a universal joint connection between said tool holder and driving shaft, and a spring interposed between said driving shaft and said tool holder for absorbing the shocks caused by said G3 universal joint.

2. In a valve grinding apparatus, the combination of a valve stem pilot with a tool holder adapted to be slidably and rotatably mounted on said pilot and a grinding wheel carried by said C5 grinding wheel being tilted with respect to the axis of rotation of said tool holder whereby said grinding wheel engages the work only at one side,a driving shaft for said tool holder, a universal 'joint connection between said tool holder and driving shaft, a spring interposed between said driving shaft and said tool holder for absorbing the shocks caused by said universal joint, said tool holder comprising a sleeve nonrotatably supported upon said pilot and antibody of said tool holder for supporting said tool holder for rotationat a high rate of speed.

3. In a Valve seat grinding apparatus, the combination of a tool holder with a grinding wheel and means for supporting said grinding wheel xedly upon said tool holder and with the grinding wheel tilted with respect to the axis of said tool holder, said means comprising a 'threaded connection and a tapered spacing member interposed between a part of said grinding wheel and said tool holder. v

4. In an apparatus for grinding valve seats,

the combination of a valve stem pilot with a sleeve slidably mounted on saidv pilot, a tooll holder comprising a casing embracing said sleeve, anti-friction means interposed between said casing and sleevefa grinding wheel carried by said casing, and resilientl means interposed between a valve stem guide and said sleeve for lifting said tool holder and grinding `wheel ofi a valve seat.

- 5. In an apparatus for grinding valve seats, the combination of a valve stem pilot with a sleeve slidably mounted on said pilot, Aa tool holder comprising a casing embracing said sleeve,

Vanti-friction'means interposed between s aid casting and sleeve, a grinding wheel carried` by said casing, resilient means interposed between a valve stern guide and said sleeve for lifting said tool holder and grinding wheel od a valve seat, and'a spacing collar engaging said sleeve about said pilot and extending outward from said casing into engagement with said resilient means.

6. In an apparatus for grinding valve seats, the combination of a valve stein pilot with a sleeve slidably mounted on said pilot, a tool holder comprising a casing embracing said sleeve, antifriction means interposed between said casing and sleeve, a grinding wheel carried 'by said casing, resilient means interposed between a valve stemguide and said sleeve for lifting said tool holder and grinding wheel ofi a valve seat, and a spacing collar engaging saidsleeve about said pilot and extending outward from said casing into engagement with said resilient means, said spacing collar having a retaining shoulder at its upper end and being split rhto' permit said shoulder to spring inward for the removal of said spacing collar from said tool holder.'

7. In a valve seat grinding apparatusthe com- 'bination'of a valve stem pilot with a tool holder rotatably and slidably mounted with respect to said pilot, a. grinding wheel carried by the end of lsaid tool holder and positioned to engage a valve seat, and a tapered spacing member interposed between said grinding wheel and said tool holder to tilt said grinding wheel with respect to said tool holder. i

8. vIn a valve seat grinding apparatus, the combination of a valve stem pilot with a tool holder of said tool holderand positioned engage a valve seat, and a tapered spacing member interposed between said grinding wheel and said tool holder to tilt said grinding wheel with respect to said tool holder, said spacing member compris- 5 ing a collar having a cylindrical iiange embracing said tool holder and indicia carried by said tool holder for indicating predetermined positions of the collar for dressing and grinding operations.

9. In a valve seat grinding apparatus, the combination of a tool holder with a rotatably mounted spacing member carried by the lower end of said tool holder, said tool holder having a reduced threaded portion passing through Said l5 spacing member, and said spacing member having an enlarged aperture, said spacing member being of greater thickness at one side than the other side, and a grinding wheel carried by the reduced threadedv end of said tooi holder, said 20 grinding wheel having a threaded bore loosely` fitting said threaded end whereby said grinding wheel may be tilted on said tool holder when threaded home, due to the dierent thicknesses of the parts of said spacing member.

. 10. In a valve seat grinder, the combination of a pilot adapted to be lxedly mounted in a valvev stem guide, said pilot having an upper cylindricai portion, a tool holder slidably and rotatably mounted on said cylindrical portion and guided 3o thereby, a grinding wheel carried by said tool holder for engaging a valve seat, said tool holdeil having an aperture in its 'upper end for receiving. a driving member, complementary non-circuiar formations on said driving member and seid tool 35V holder at said upper end whereby a limited universal joint connection is formed between said driving member and said tool holder, and a. spring located in said tool holder below said driving member and engaging said driving member for 40 absorbing the shocks caused b5 said driving member on said tool holder.

il. In a valve seat grinding apparatus tool holder comprising a body having a cylindrical part adapted to slidably engage a 'valve stem 45 pilot, a grinding tool carried by saidtool holder and adapted to be rotated and reciprocsted on said pilot by said tool holder, said tool holder having a. drive socket in its upper end, a driving member having a driving connection with said socket, and a resilient member 'located insaid socket and engaging said driving member to absorb shocks and to permit said grinder to ride upward over grindings between the grinding wheel face and the valve seat, said tool holder socket and driving member connection comprising engaging non-circular formations in said socket and on said driving member and having sufliclent clearance for a limited universal movement between said driving member and said tool holder at said socket.

FRANS 0; AlZiBEiRTSON.V

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