US1991834A

US1991834A - Method of grinding valve seats

Info

Publication number: US1991834A
Application number: US643584A
Authority: US
Inventors: Frans O Albertson
Original assignee: Albertson and Co Inc
Current assignee: Albertson and Co Inc
Priority date: 1932-11-21
Filing date: 1932-11-21
Publication date: 1935-02-19
Anticipated expiration: 1952-02-19

Description

1935- F. o. ALBERTSON METHOD OF GRINDING VALVE SEATS Filed Nov. 21, 1932 7 9 6 a 5 a 75!] 1 f 2 %2 1 5 5 5m 7 24 a I a 9 52515 7 212%? WW v w gg a u x Patented Feb-19,1935 I UNITED STATES? 'mz'rnon or. GRINDING vALvE SEATS Frans 0. Albertson, Sioux City, Iowa,.assignor to Albertson a Company, Inc., Sioux City, Iowa, a corporation oi. Iowa Application November 21, weasel-n1 No. 643,584

1 Claim.

5 valve seats of internal combustion engines.

However, the methods and apparatus are of general application and may be utilized for valves of different 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.

the grinding wheel in an orbit to engage all parts of the valve seat with a grinding wheel which is of a smaller diameter. A full seat contact between the grinding wheel and the valve seat results in the clogging or loading of the wheel 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 off 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 grindof labor.

seats for internal combustion engines is toward ing tool.

One of the objects of the invention is the provision of an improved method of reconstructing.

. valve seats by means of which the extremely hard seats of stellite, tungsten steel, or other hardened alloys can be ground quickly and uniformly to produce a finished seat, with a minimum amount The tendency in construction of valve Another object of the invention is the provision of an improved method of handling a grinding tool which is adapted to disperse the cuttings continuously and prevent loading of the wheel or filling ofthe interstices between the abrasive 5 particles of the wheel at the surface with the cuttings, the cuttings 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 pointe where the wheel does not actually engage the seat.

Another object of the invention is the provision of an improved method of 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 finished seat, the quality of which is commensurate with the quality of a seat secured by a handlapping operation.

The present application relates particularly to the method of grinding valve seats and to the complete combination of apparatus used therefor, and a co-pending application, Serial No. 648,564, relates to certain novel elements of the complete combination, comprising the valve seat grinding machine. 1

Otherobjects and advantages of the invention will be apparent from the following description and from the accompanying drawing, in which similar characters of reference indicate similar partsthroughout the several views Referring to the drawing, of which there is but one sheet,

Fig. 1 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 of the guide, the assembly including the motor driver, tool holder, grinding wheel and pilot;

Fig. 2 is a fragmentary view similar to Fig. 3, showing an elevational view of the grinding wheel with the parts in proper position for grinding, and showing the angular relation between the frusto-conical surface on the grinding wheel and the valve seat.

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

As an understanding of the apparatus is neces-, sary to an explanation of the method, the grinding and dressing apparatus will first be described in sufllclent detail to explain the method.

to confine the lubricant between the races.

Referring to Fig. 1, the complete assembly of grinding apparatus preferably includes a motor driver 20, a tool holder 21, a grinding wheel 22, and a pilot stem 23.

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, which is provided with a valve stem guide 26.

The pilot 23 is of the type having a lower cylindrical part 27 which fits the substantially cylindrical part of the valve stem guide 26 very closely, within one one-thousandth of an inch, for the purpose of centering the pilot 23 in the guide.

The pilot is also provided with a very gradually tapered wedging portion 28 which extends 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 the pilot in place.

Any other type of pilot which is capable of being accurately centered in the valve stem guide 26 and fixedly secured therein may be used, such as the expanding pilot covered by my prior Patent, No. 1,806,189.

The apparatus is provided with a. suitable m0- tor driver, one type of which is shown in Fig. 1.

It has been found that in order to obtain a proper grinding action with grinding wheels of this type the wheel must have a minimum speed.

of 3500 linear feet per minute, and a maximum of 6,000 linear feet per minute, at the grinding surface. The electric motor, for examplemay have a speed of 3600 revolutions per minute, and in order to provide for grinding wheels of the various predetermined sizes, I prefer to provide a 6,000 R. P. M. driver and a 9,000 R. P. M.

driver, the latter being used for smaller whee1s.-

Referring to Fig. 3, this is a vertical sectional view through the tool holder. The pilot 23 is provided with a substantially cylindrical upper part 100, which may be provided with an aperture 101 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 21 is also provided with a tubular metal member 102 having an elongated and accurately machined bore 103 for slidably and rotatably receiving the cylindrical portion of the pilot 23.

The tubular member 102 is preferably provided with the reduced end portions 104, 105, each of which is slightly tapered to effect a close frictional fit with the

inner race rings

106, 107 of the self-aligningball bearings. The ball bearings also comprise the

balls

108, 109, and the outer rings 110, 111. Each of the outer race rings is preferably spun over at one end and at the inner corner 112 to secure an oil seal ring 113 to the bearing. Appropriate packings 114 prevent the lubricant from leaking out of the bearings beyond the oil seal. 113.

Metal plates

115, 116 slidably mounted on the tubular member 102 are located below the upper ball bearing and above the lower ball bearing, As lubricant is not required in the annular space 117, a spacer sleeve 118 is located in the tool holder casing 119 between the

plates

115, 116 to hold the plates in proper position against the lar metal member, such as a steel member, which is provided with a cylindrical bore 120 adapted to receive the outer races 110, 111 and the spacer sleeve 118.

The lower end of the tool holder casing 119 is provided with an annular inwardly extending flange 121 forming an annular shoulder 122 against which the lower ball bearing rests, and the lower end of the tool holder casing 119 is provided with a reduced tubular boss 123 for supporting a. grinding wheel. The tubular boss 123 has a bore 124 of suflicient size to provide a clearance between the walls of the bore 124 and the tapered pilot 23, since the tool holder is to be guided on the pilot by the sleeve 102 and the ball bearings at each end of the sleeve.

The tubular boss 123 is provided with threads 125 for receiving the threads on the inside of a metal hub 126 which supports the grinding wheel 127 of carborundum or other solid abrasive 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

v the smooth dressing for finishing.

The lower end of the tool holder 21 is provided with a flat annular surface 128 which extends at right angles to' the axis of the tool holder, and it is also provided with a cylindrical surface 129 serving as a guide for receiving the cylindrical flange 130 on a collar 131.

This collar will be called the Dress-grind collar, and its function and structure will be described in detail hereinafter. The collar comprises the cylindrical flange 130 slidably fitting upon a cylindrical part 129 of the tool holder body 119, and the collar comprises an end plate 132 which tapers in thickness from the left side toward the, right, as shown in Fig. 3. The end plate 130 hasan enlarged bore 133 which may be threaded so that the Dress-grind collar can be threaded over the threads 125, but it is loosely supported at the unthreaded part 134 between the threads 125 and the flat end 128 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 onthe end of the tool holder, but the collar does not fall off the tool holder due to the threads 125, and the parts of the tool holder are thus permanently assembled together in such manner that no part is apt to be lost.

The grinding wheel 127 comprises the metal vhub 126, previously described, and the grinding wheelbody of abrasive material, which is preferably provided with a fiat top 135, a cylindrical outer surface 136, and a frusto-conical grinding surface 137. The bottom 138 of the grinding wheel may be fiat or take any appropriate shape. The cylindrical surface 136 of the grinding wheel is merely present on account of a desire to make the grinding wheel of suflicient thickness so that it may be dressed and-used over again for a longer period of time until the stone becomes too thin. As the stone is dressed and used up, the length of the cylindrical surface 136 will diminish, and the stone will become thinner in a vertical direction.

On the small stones it is unnecessary to provide a guard,v as the speed at which the stones are rotated is not suflicient to cause any danger,

diameter.

- The guard comprises a stamped steel cup haying a flat end portion 139 and having a down-, wardly extending cylindrical border flange 140 encasing the end and a part of the periphery of the, stone. The guard may be secured to the hub 126 by spinning over the upper edge of the hub outside the body of the guard.

A fiber washer 141 is preferably interposed between the Dress-grind collar 131 and the end of the tool holder so as to facilitate the unscrewing of the grinding wheel from the tool holder,

together so tightly that difliculty is encountered in taking the grinding wheel off again.

The complete assembly preferably includes a helical coil spring 142 which is interposed between the upper end of the valve stem guide 143 and the lower end of the tool holder.

It was found that the friction of the tubular boss 123 against the coil spring 142 at the high rates of speed used was so great as to heat the spring and draw the temper from the spring and also melt the sulphur in the grinding wheel. In order to prevent this friction, the tool holder is preferably provided with a thrust sleeve 144 having a bore 145 of sufllcient size to receive the cylindrical part 100 of the pilot, and having an annular flange 146 engaging the end 147 of the guide sleeve 102. The, thrust sleeve 144 is preferably split longitudinally to permit it to be sprung together, and the flange 146 is sufficiently narrow so that when the split end is sprung together it will pass through the bore 124. The flange 146, however, retains the sleeve in the bore 124 when the spring is removed. The thrust sleeve144. has a clearance with the bore 124 in the tubularv boss 123, and the thrust sleeve extends outward beyond the grinding wheel into engagement with a sheet metal cup shaped member 148.

The cup shaped member 148 provides a seat for the upper end of the spring 142. Springs of various length should be used, depending upon the distance from the end 143 of the valve stem guide to the valve' seat 149. For instance, the top of the spring should be about three-fourths to one inch above the valve seat when the tool holder is removed, to provide suflicient compression for lifting the grinding wheel off the seat. Several lifting springs of different lengths are included as regular equipment.

In the operation of the device, the pilot stem 23 is, of course, fixed in the guide 26. The guide sleeve 102 is slidably mounted upon the pilot stem and could rotate, but the friction between the guide sleeve 102 and the pilot is greater than the friction between the inner and outer races of the ball bearings. Therefore, the guide sleeve 102 does not rotate.

There is no friction between the grinding wheel and the spring when the thrust sleeve 144 is utilized. The heating of the spring is thereby avoided and the temper of the spring is not drawn. Referring to the Dress-grind collar 131, one side of the collar bears thenotation Dress on the cylindrical flange 130, while the other side of the collar bears the notation Grind", and the cylindrical casing 119 of the tool holder has a mark and the indicia zero. This indicia is used for setting the collar for the dressing or grinding operations respectively and the theory and 0peration of these elements will be described in detail hereinafter.

It should also be noted that the threads 125 are sufficiently loose with respect to the hub 126 so that the position of thegrinding wheel 127 is determined by the tapered thickness of the body 132 of the "Dress-grind" collar 131; that is, the. plate 132 being thicker at one side than the other, the grinding wheel 127 engages plate 132 and is secured against the plate by the threads 125 in a tilted position, so that the grinding wheel enages the seat 149 at one side, as shown in Fig. 3, but only comes into close proximity to the seat at the other side of the grinding wheel.

The looseness of the threads 125 permits this tilting of the grinding wheel on the tool holder. as the metal surfaces otherwise become screwed The upper end of thetool holder body 119 is provided with threads 150 which may be right hand threads, and the tool holder cap 151 may vbe provided with threads 152 in a left hand di-- 'rection.

Connecting sleeve 153 is provided with complementary threads and threaded into the casing 119 and the cap 151.

Connecting sleeve 153 is provided with an inwardly extending collar flange 154 forming a seat for a relatively heavy coil spring 155. At its other end the coil spring 155 is seated against. a flat steel plate 156, slidably mounted in a bore 157 in a universal joint sleeve158. The cap 151 comprises a cylindrical member having an inwardly extending annular flange 159 provided with a bore 160 having a curved surface for engagement with the ball 161. The cap is also adapted to receive the universal joint sleeve 158, which comprises a hardened steel tubular member, having four axially extending slots 162 located ninety degrees apart.

The lower end of the universal joint sleeve 158 is provided with. axially extendingslots 163 for receiving the axially projecting ridges 164 carried by the connecting sleeve 153. Slots and ridges 163, 164 provide a driving connection between the

sleeves

158 and 153. A driving connection is provided between the ball 161 and the sleeve 158 by four transversely outwardly projecting cylindrical steel pins 165 engaging in the slots 162.

The slots 162 are of suflicient length so that the pins 165 may move upward and downward in the slots as the ball 161 rotates in the socket provided in the end of the cap 151. Ball 161 is preferably provided with a threaded bore 166 for receiving the reduced threaded end 167 of the ball shank. The ball shank is tapered at 88 for reception in the drive sleeve of the motor driver, and is provided with a transverse pin 87. to be received in the groove 85 of the motor drive shaft. The motor driver, therefore, rotates the shank 88 and ball 161, and with it sleeve 158, sleeve 153, cap 151, casing 119, and grinding wheel 127.

The guide sleeve 102 and pilot, with the inner races of the ball bearings, do not rotate, and the self'ali'gning 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 seat 149.

As it is practically impossible to hold the motor driver 20 axially above the tool holder 21, the universal joint provided by the ball 161, cap 151, and sleeve 158 permits the driving of the tool holder by the motor driver, although the moor driver is not held in direct axial 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 resilient connection is used, and the compression spring 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 finish. The shocks caused by the use of the universal joint are not transmitted to-the grinding wheel when the spring 155 is utilized, but are absorbed by the spring.

Referring to Fig. 2, this showsthe tool holder and grinding wheel in the grinding position, and the Dress-grind collar 131 has been turned so that the word Grind appears under the mark zero.

The rightsid'e of the grinding wheel is accomplishing the grinding action, as evidenced by the dark mark 168 on the frusto-conical surface of the grinding wheel, and the grinding wheel 22 does not come into contact with the valve seat at the side 169, as shown by the space between the wheel and the seat at 169, this clearance being, however, exaggerated for the purpose of illustration. The grinding wheel is, however, sufficiently 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 finished seat and a more uniform grinding action, because the seat is actually ground to conform to the surface of the grinding wheel and is not marred by the presence of grindings between the wheel and the seat.

The present grinding, wheel is preferably dressed apart from the valve seat 149 so that the abrasive which is dressed off the wheel does not fall on the valve seat. -Any suitable dressing apparatus may be utilized which is adapted to dress the grinding wheel accurately to frusto-conical form.

Referring to Fig. 3, it will be observed that the thick part of the Dress-grind collar 131 is located at the right side-of the stone for grinding, thereby tilting the stone downward at the right in Fig. 3, the stone being in close proximity to the valve seat at the left in Fig. 3.

It should be understood that the proportions of the taper on the spacing plate of the Dressgrind collar may be varied, and I do not wish to limit myself to any particular taper. This taper is preferably made such that the grinding wheel engages only at one side over substantially one-third'of the grinding periphery of the wheel, and the taper is preferably such that the other part of the grinding wheel is located 'in close proximity to the seatso as to effect a cleaning action by virtue of its proximity and by virtue ofthe air current caused by such proximity.

For example, in one embodiment of the invention the taper in the spacing plate of the Dressgrind collar is such that the angle between the upper and lower surfaces of the Dress-grind collar diverges two-tenths of a degree from the parallel.

The grinding wheel is not dressed at the. angularity desired for the seat, but at such an angularity that when the grinding wheel is tilted, that element of the grinding wheel which engages the seat 149 at the right side in Fig. 3, or in Fig. 2, is located at the angle desired.

The method of finishing valve seats or reconstructing valve seats may be carried out by the apparatus described, and is preferably practiced as follows:

A recess is first cut in the seat of the valve in the,engine block, the recess being adapted to receive a new valve seat ring of high carbon steel, stellite, or some other hardened alloy better adapted to withstand the heat and impact to 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 grinding wheel of the grinding machine used in carrying out the present method is provided with a frusto-conical grinding surfacewhich is formed by a dressing tool, and this grinding wheel is tilted with respect to its axis of rotation so that the axis of the frusto-conical surface is .at a slight angle to the axis of rotation by means of the Dress-grind collar on the tool holder.

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 grinding wheel is supported above the valve seat by means of the compression spring. The motor driver is applied to the upper end of the tool holder, and while the motor is operating at a high rate of speed within the range described the motor and tool holder are pressed down lightly until the grinding wheel engages the seat.

The grinding wheel should not be pressed so hard that the speed of the wheel 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 moved up 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 different points rotatively of the seat, and the random engagement between the grinding wheel and the seat will give a more unie form action and permit more finished 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 side 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 seat in the same manner to produce a finished seat, or a relatively smooth stone may bedressed 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.

It will thus be observed that I have invented an improved method, an improved grinding tool assembly, an improved tool holder, an improved grinding wheel, and otherapparatus 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.

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

The present results are all accomplished by means of a very-simple type of apparatus, which does not require but a single drive shaft and the 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 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 scope of the appended claims.

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

The method of reconstructing valve seats which comprises rotating a 'frusto-conical grinding stone upon an axis which is at an angle with respect to the axis of the frusto-cqnical grinding surface, the degree of angularity being such that that part of the frusto-conical surface not in contact with the valve seat is in close proximity to the valve seat to effect a dispersement of the cuttings.

. FRANS O. ALBERTSON.