US2287697A - Valve seat grinder - Google Patents

Description

June 23, 1942. H. G. MILLER VALVE SEAT GRINDER Filed Feb. 7, 1941 2 Sheets-Sheet l WW; M

June 23, 1942. H. G. MILLER VALVE SEATGRINDER Filed Feb. 7, 1941 2 Sheets-Sheet 2 whereby a liquid lubricant and Patented June 23, 1942 UNITED STATES AT ENT *o FFIC'E 9 Claims.

This invention relates to valve seat grinding machines, and more particularly to a machine for grinding hardened valve seats in one-piece cylinders of internal combustion engines such as the radial air-cooled engines now commonly in use.

It is now common practice to provide the valve ports of internal combustion engines with valve seat inserts of hardened metal whereby wear at this point is reduced to a minimum. In servicing these hardened valve seatsit is necessary to employ an abrasive wheel which is applied to the valve seat and is preferably rotated at high speed.

It has been found that in use abrasive wheels operated at the desired high speed have a tendency to glaze over and lose their cutting edge, thereby rapidly becoming worn and tending to create an irregular surface on the valve seat. Also the valve seat overheats, and the process must be interrupted or the speed of operation reduced.

To overcome the above difficulties encountered in this type of grinding, and particularly to accomplish this in the grinding" of normally inaccessible valve seat inserts in one-piece cylinder heads, the present invention includes .means coolant may be supplied to the cutting edge'ofthe abrasive wheel during the grinding operation, and also automatic means whereby the" grinding wheel or other tool mayintermittently be lowered to and raised from the valve seat in a predetermined cycle of movement so that said" lubricant and coolant is permitted to reach the contacting surfaces of said tool and work and prevent excessive wear or overheating.

The coolant serves to keep down the temperature of the grinding wheel and washes the metal grindings and the like out of the path of the tool, thus aiding in the prevention of glaze and permitting a higher cutting speed.

As heretofore more specifically set forth in my prior Patent No. 2,208,680, it is essential that a proper alignment of the respective parts be accomplished throughout the grinding operation whereby the grinding wheel is retained in proper axial alignment with the valve stem passage of the cylinder to be ground and proper seating of thevalve'at all times may be assured. To accomplish this the present invention includes a pilot of particular design having a drive shaft journaled therein and a grinding wheel driven by said drive shaft and supported upon and accurately aligned by said pilot during rotation.

For'most accurate alignment of the'tool' during the grinding operation it is desirable that a suflicient aligning surface be provided immediately adjacent the.cutting surface of the tool and as close as possible to the plane of its operation. To accomplish this in the limited space incident to the use for which this device is intended, the present invention employs a plurality of interfitting guide surfaces which assure proper alignment of the valve seat grinding tool during both rotary and axial movement thereof.

In the drawings:

Fig. 1 is a vertical sectional view of the machine taken on a line substantially corresponding to line l-l of- Fig. 4, most of the operating mechanism being shown in elevation.

Fig. 2' is an enlarged vertical axial section through the mechanism shown in Fig. 1, and revealing details of the pilot arrangement.

Fig. 3 is a detail sectional view taken on a line substantially corresponding to line 3-3 of Fig. 2.

Fig. 4 is a sectional view of the structure shown in Fig. 1 and taken on a line substantially corresponding to line 44 of Fig. 1.

Referring to the drawings in detail. As hereinbefore stated it is important that the pilot be accurately and immovably secured in place in the cylinder block valvestem passage throughout the entire valve seat surfacing operation. This is accomplishedin the present invention by the use of the special guiding'means shown, which comprises a pilot 'I having an enlarged head portion 2- and a tubular shank'3' which latter has a threaded end 4. This pilot has a tubular bore 5 which is coaxial with the head 2 and the shank 3. From several suchpilots of assorted shank sizes, one is selected; the shank of which will closely fit the inside of the valve stem passage of the cylinder whose-valveseats ar'eto be ground. This valve'stem passage may have'a guide bushing 6 which may have beenreamed or otherwise prepared as described in my prior patents above cited. 1 The pilot I is then inserted in place in the valVestem guide with the shank passing through the valve stem guide and extending msmeorme cylinder. A" suitable internally-threaded lock nut 1' having a tubular dependingportion 8 maythen' be screwed onto the threaded end'of the pilot and the valve stem guide 6 is" thus securely clamped between the head 2 of the pilot andthe lock' nut I. All of the above may be done-on thework benchaway from the rest of themachin.

With the pilot secured iii-place; the cylinder may then be taken to themachine and be bodily lowered over a drive shaft 9 which enters the the threaded end 4 of spanner nut 22 having axial bore 5 of the pilot and extends entirely therethrough. This drive shaft 9 is already in place in the machine, and, after the cylinder is in place the drive shaft may be extended or retracted as hereinafter described, so as to project slightly above the end of the pilot head 2.

To retain the pilot and cylinder head assembly in place the tubular depending portion 8 of the lock nut is grasped and held by the jaws of a split collet ID. This collet is provided with a closing sleeve H which may be keyed thereto to secure it against rotation, and is itself secured against rotation in a supporting member l2. The usual threaded portion l3 of the collet is engaged by an internally threaded central opening in a worm gear M, which is secured against axial movement by the bearing surfaces l5 and IE on each side thereof. This worm gear may be manually rotated by a suitable hand wheel (not shown) driving through a shaft I1 and a worm IS. The collet l0 securely clamps the lock nut, pilot and cylinder in vertical position and holds them against rotation during the entire refinishing operation.

The grinding head may next be placed in the cylinder and lowered over the enlarged portion 2 of the pilot and may be secured to the upper end of the drive shaft in a manner subsequently described in detail. The grinding head is an important feature of the present invention, and is preferably constructed as shown in Fig. 2 wherein an annular abrasive wheel l9, having the desired metal cutting characteristics, is secured to a downwardly extending reduced portion 20 of a grinding head rotor 21. The stone may be secured in place upon the head by an annular holes 23 for engagement by a suitable spanner wrench.

The grinding head rotor 2| has a hollow interior forming an annular oil reservoir 24 which may be provided with a filler opening and plug 31. This rotor is secured at the top to a driving disc 29 which is keyed to the splined upper end of the drive shaft 9, and the rotor, driving disc, and drive shaft rotate as one.

The rotor is also provided with an axially aligned bearing bushing 21 upon which it is guided in its rotation and which may be secured in the rotor by a press fit or by other suitable means. This bearing bushing may be provided with small oil feeding openings 28 leading from the annular oil reservoir to the inner surface of said bushing.

A second bearing member is provided comprising a stationary sleeve 29 having a peripheral collar 30 at one end. The outside of this sleeve has a smooth bearing contact with the inside of the rotor bushing. The sleeve 29 is secured to the head of a stator member 3| which may be provided with a splined depending portion engaging companion splines in the enlarged bore of the pilot head 2. These splines engage each other with a sliding fit. This stator also has an axial bore 32 through which the drive shaft 9 passes and which may be journaled therein. With this construction the splined stator and sleeve may be axially moved without rotation or loss of alignment with the pilot. Fig. 3 shows the details of these parts and the manner in which they are interrelated.

Several important benefits will be noted from the above construction. 7 Thus, the bearing surface between the rotatable bushing 21 and the stationary sleeve 29 is protected at all times from grit, abrasives, and cuttings.

In addition, this bearing surface is kept supplied with lubricant from the reservoir 24 and, also, the bearing surfaces are not disturbed or disassembled when the unit is transferred from cylinder to cylinder and therefore the possibility that it will be exposed to grit and abrasives is reduced to a minimum. This latter is achieved without loss of accuracy in alignment of the abrasive tool with the pilot, for the long splined surfaces assure that when assembled the parts will be in coaxial alignment.

The rotor 2| and drive disc 26 may be secured to the splined upper end 33 of the drive shaft by means of a drive plate 34, provided with a splined central aperture corresponding to the splines of the upper end of said shaft. The shaft has a circumferential groove 35 interrupting said splines so that by placing the drive plate 34 over the end of the drive shaft, aligning it with the circumferential groove 35 and bodily rotating it out of alignment with said splines, it is secured against axial movement and when the discs 26 and 34 are then fixed together, the entire head is secured in place and becomes axially movable and rotatable with said drive shaft. A ball and spring detent 36 may be employed to automatically retain the parts in adjusted position and a screw 25 operating in a suitable slot may be used to lock the discs 26 and 34 in the selected adjustment.

An intermittent axial movement of the drive shaft 9 is provided by means of an automatic mechanism comprising a beam 38 (Fig. 1) pivoted at one end and having at the other end a roller 39 which rests upon the irregular upper surface of a rotatable cam 40. In operation, rotation of this cam raises and lowers the roller 39 and the adjacent end of the beam 38.

As shown in Fig. 4, an intermediate portion of the beam 38 is formed to provide a yoke 4| having a pair of upwardly opening slots 42 in which a drive shaft thrust bearing is pivoted by means of laterally extending bearing pins 43. With this arrangement, the drive shaft may be axially reciprocated at each revolution of the cam, and, inasmuch as the grinding head is axially movable with said shaft it is also raised and lowered so that the grinding wheel I9 intermittently engages the valve seat.

The pivot comprises a .pin 44 journaled in the end 45 of the beam 38. The pin may be suitably mounted for vertical adjustment as by being secured to a cross head block 46 or the like which may be adjusted to a raised or lowered position by a vertical shaft 41 provided adjacent its upper end with a hand wheel 48 threaded to said shaft. Rotation of this hand Wheel raises or lowers the shaft and cross head block 46 and the pivot 44 and therefore raises or lowers the pivot point of the beam 38. It will be apparent that adjustment of the hand wheel 48 will vary the limit of. operation of the grinding stone l1. 7

During the grinding operation drive shaft 9 may be grasped and rotated by means of a readily releasable coupling assembly comprising a split collet member 49 having a threaded intermediate portion 50 and, an enlarged hand wheel portion 5|. This, collet member may be screwed into a threaded extension 52 on a drive shaft pulley 53, this pulley being provided with an inclined inner hub surface 54 against which the inclined split colletend 55 bearswhen the split .collet member 49 is threaded. intoplace. This inclined surface serves as a closing ring to cause the split ends to engage the drive shaft when the enlarged hand wheel part is turned to thread the split collet into the pulley extension 52. The outer surface of the drive pulley extension 52 is housed within and supports the inner race 56 of a ball bearing, the outer race 51 of which is cradled in a ring-like bearing housing 58 having the laterally extending pins 43.

By the above described arrangement a floating thrust bearing assembly is provided sup- -ported by the beam 38 and movable therewith.

The slots 42 in the yoke 4| are of sufficient size to permit slight lateral accommodation of the bearing during movement of the beam.

A coiled compression spring 59 is positioned around the drive shaft 9 and has collars 60 and SI adjacent each end. These collars are urged apart by the compression. spring which also resiliently urges the drive pulley and bearing housing downwardly, preventing any play between those parts and the beam 38 and assuring that the roller 39 will always be in contact with the irregular upper surface of the cam 60; The upper collar Bllperipherally engages a sealing ring 62 by which the bearing 63 is protected from grit and foreign matter.

In the embodiment shown, the nut l is provided at its upper end with a sleeve 64 0f hardened material recessed in the upper end of the nut and positioned to engage the valve stem guide of the cylinder. With this construction, wear at this point is minimized.

The grinding head may be driven at a high rate ofspeed by an electric motor 65 having a large drive pulley 06 which is connected by a suitable belt to the smaller drive pulley 53 on the drive shaft. This same motor may be provided with another pulley 6! which may rotate the drive shaft 68 of a pump 69. From the pump shaft another belt may drive a countershaft 10 which in turn is connected to pulley H on a camshaft 12.

With the embodiment illustrated, it has been found that satisfactory results ca be obtained with a H. P. motor rotating at 3600 R. P. M. and suitably connected so as to rotate the drive shaft at a speed of 8000 R. P. M. By rotating the cam shaft at 60 R. P. M. the grinding head is axially reciprocated once each second, and, by rotating the pump shaft at a speed of 900 R. P. M., a suitable volume of lubricant and coolant may be supplied with the usual pumps which are applicable to such use.

Th pump 69 provides a constant flow of cooling and lubricating fluid which may be conducted by a supply pipe 72a to the top of the inverted cylinder and into which it may be discharged to fiow out of the valve port having first passed between the grinding wheel and the valve seat being ground. As this coolant falls from the valve port it is collected on the trough-like top 13 of the machine. It then returns through the drain pipe 14 to the pump 15, first passing through a'suitable strainer 76 positioned under the outlet of the drain pipe to remove solid impurities therefrom.

In operation the cylinder is first provided with the pilot and lock nut as hereinbefore described. This assembly is then looked in place by the split collet. The grinding head is then lowered into place over the drive shaft and pilot inside the cylinder and, with the cam 40 turned until the roller carrying the free placed on the machine and end of the beam is resting on the lowermost point of the cam in the position shown in Fig. 1, the grinding head is locked in place. The drive shaft may then be locked into place by tightening the hand wheel 5|.

With the machine in operation the amount of material removed from the valve seat may be governed by adjustment of the hand control Wheel 48 which is gradually turned to lower the pivot point of the beam 38, and therefore lower the lower limit of movement of the grinding head.

With the construction shown it is obvious that the operation may be interrupted and the grinding head readily removed and the progress of the operation observed and tested without disturbing the lignment or setting of the parts in the machine. This is an important feature of the present invention.

Further modifications will be apparent to those skilled in the art and it is desired, therefore, that the invention be limited only by the scope of the appended claims.

Having thus described my invention, what I claim and desire to secure by Letters Patent is:

1. In a valve seatgrinding machine for refinishing valve seats and valve seat inserts in one piece airplane cylinders by means-of a high speed abrasive tool driven through a valve stem passage, the combination of a pilot having an axial bore and adapted to extend through said valve stem passage and form a guiding fit therein and looking means to secure said pilot in place with a drive shaft extending through said bore and rotatably and axially movable therein, a high speed abrasive tool mounted upon and guided by one end of said pilot and fixed to said drive shaft for rotary and axial movement therewith, an axially movable non-rotating drive shaft bearing member encompassing the upper end of said drive shaft and axially movable therewith and having a non-rotatable connection with said pilot sleeve whereby alignment of said drive shaft and said tool are provided irrespective of the axial posiout interrupting the rotary motion thereof.

2. In a valve seat grinding machine for refinishing valve seats and valve seat inserts in one piece airplane cylinders by means of a high speed abrasive tool driven through a valve stem passage, the combination of a pilot having an axial bore and adapted to extend through said valve stem passage and form a guiding fit therein and locking means to secure said pilot in place shaft for rotary and axial movement therewith, an axially movable non-rotating drive shaft bearing member encompassing the upper end of said drive shaft and axially movable therewith and having a non-rotatable connection with said pilot sleeve whereby alignment of said drive shaft and said tool are provided irrespective of the axial position of said tool, and means to intermittently impart reciprocating axial movement to said 3. An apparatus for automatically controlling the grinding operation of a valve seat grinding head comprising a' tubular pilot adapted to engage the inside of the usual valve stem passage, a drive shaft for said grinding head extending through said tubular pilot to impart rotary and axial movement to said grinding head, and means to rotate said drive shaft to rotate the grinding head and reciprocate said grinding shaft axially and intermittently a sufiicient distance to bring said grinding head into engagement with said valve seat and to move it out of engagement therewith.

4. A valve seat grinding apparatus for one piece cylinder heads having a valve seat and a valve stem passage coaxial therewith comprising a tubular pilot extending through the valve stem passage, a drive shaft extending through an axial bore in said tubular pilot and having a grinding head on one end thereof, and means adjacent the opposite end of said drive shaft for imparting both a rotary movement thereto and for imparting an intermittent reciprocating axial movement thereto sufficient to bring said grinding head into engagement with said valve seat and to move it out of engagement therewith.

5. A valve seat grinding apparatus for one piece cylinder heads having coaxial valve seats and valve stem passages comprising a tubular pilot extending through the valve stem passage, a drive shaft extending through an axial bore in said tubular pilot and having a grinding head on one end thereof and means adjacent the opposite end of said drive shaft for imparting both a rotary and an axial movement thereto, and manually adjustable control means operable on said drive shaft to limit the axial movement thereof.

6. A grinder for a valve seat having a valve stem passage coaxial with said seat in which the valve stem is reciprocated comprising a pilot insertable and securable in said valve stem passage, a rotary grinding tool rotatably mounted on and centered with respect to the valve seat by said pilot and reciprocably mounted on and guided by said pilot, means for rotating said grinding tool, and means for intermittently reciprocating said grinding tool a sufficient distance to bring said grinding head into engagement with said valve seat and to move it out of engagement therewith, the bearing between said tool and pilot comprising a first bearing member non-rotatably and reciprocably mounted on said pilot and reciprocable with said tool, and a second bearing member rotatably engaging said first member, rotatable with said tool and reciprocable with said tool and first bearing member.

'7. A grinder for a valve seat having a valve stem passage coaxial with said seat in which the valve stem is reciprocated comprising a tubular pilot insertable and securable in said valve stem passage, a rotary grinding tool, a drive shaft for said tool extending through and rotatably mounted and centered with respect to the valve seat by said pilot and reciprocably mounted on and guided by said pilot, and means for intermittently reciprocating said grinding tool a sufficient distance to bring said grinding head into engagement with said valve seat and to move it out of engagement therewith.

8. A pilot for use in a valve grinding apparatus of the character described and wherein a valve grinding tool is both rotated and reciprocated comprising a tubular member having a threaded portion adjacent one end and a tool aligning head adjacent the other end, said head having a coaxial enlarged bore and axially parallelgrooves in said bore.

9. An apparatus for automatically controlling the grinding operation of a valve seat grinding head comprising a tubular pilot adapted to engage the inside of the usual valve stem passage, a drive shaft for said grinding head extending through said tubular pilot to impart rotary and axial movement to said grinding head, and means to rotate said drive shaft to rotate the grinding head and reciprocate said grinding shaft axially and intermittently a sufficient distance to bring said grinding head into engagement with said valve seat and to move it out of engagement therewith, the frequency of said reciprocations being less than the frequency of the revolutions of the grinding tool.

HARRY G. MILLER.

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