US3176440A

US3176440A - Method and apparatus for grinding a cylindrical surface

Info

Publication number: US3176440A
Application number: US31325A
Authority: US
Inventors: Earl A Thompson
Original assignee: Individual
Current assignee: Individual
Priority date: 1960-05-24
Filing date: 1960-05-24
Publication date: 1965-04-06
Anticipated expiration: 1982-04-06

Description

April 6, 1965 s. A. THOMPSON 3,176,440

METHOD AND APPARATUS FOR GRINDING A CYLINDRICAL SURFACE Filed May 24, 1960 '7 Sheets-Sheet 1 IN V EN TOR.

EAFg L ATHOMPSON @267 jM ATTORA/B APril 5, 1955 E. A. THOMPSON 3,176,440

METHOD AND APPARATUS FOR GRINDING A CYLINDRICAL SURFACE Filed May 24, 1960 7 Sheets-Sheet 2 F I Z INVENTOR. j EARL A. THOMPSQN W 6- AMM A ril 6, 1965 A. THOMPSON 3,175,440

METHOD AND APPARATUS FOR GRINDING A CYLINDRICAL SURFACE Filed May 24, 1960 7 Sheets-Sheet 3 IN VEN TOR.

EAR% A. THOMPSON ATTORNEY April 6, 1965 E. A. THOMPSON 3,176,440

METHOD AND APPARATUS FOR GRINDING A CYLINDRICAL SURFACE Filed May 24, 1960 7 Sheets-Sheet 4 IN V EN TOR.

EAQ L A. THOM PSON A TTOR/VEV April 1965 E. A. THOMPSON 3,176,440

METHOD AND APPARATUS FOR GRINDING A CYLINDRICAL SURFACE Filed May 24, 1960 7 Sheets-Sheet 5 2 i2; F i 66 a l 1 sgfi/ x V A 60 I i l Wit. r

fjys

IN V EN TOR.

EA L ATHOMPSON Mam ATTORNEY April 6, 1965 E. A. THOMPSON 3,

METHOD AND APPARATUS FOR GRINDING A CYLINDRICAL SURFACE Filed May 24, 1960 '7 Sheets-Sheet 6 IN V EN TOR.

ATTORNEY April 6, 1965 E. A. THOMPSON METHOD AND APPARATUS FOR GRINDING A CYLINDRICAL SURFACE '7 Sheets-Sheet 7 Filed May 24, 1960 INVENTOR. EARL ATHOMPSON ATTORNEY BY WK /Z surface on the wheel.

United States Patent 3,176,440 IVIETHOD AND APPARATUS FOR GRINDENG A CYLINDRICAL SURFACE Earl A. Thompson, 1300 Hilton Road, Ferndale, Mich. Filed May 24, 1960, Ser. No. 31,325 Claims. (Cl. 51-281) This invention relates to face grinding, and more particularly to a method and apparatus for grinding a curved surface on a workpiece and particularly on a ledge projecting part or shoulder of a workpiece such as a valve rocker arm of an automotive internal combustion engine.

In grinding such pieces by prior methods on known machines, one of the major problems encountered is the difficulty of dressing the complement of the desired The surface dressed in the wheel must be very accurately formed as it will be accurately reflected on the work. To form such an accurate surface on the wheel, a great deal of grit must often be removed from the wheel during each dressing operation, and the dressing operations must occur frequently because the grinding operation is concentrated on a wheel area of limited width.

Accordingly, it is an object of the present invention to i provide a method of grinding a cylindrical surface of small radius with a face grinding wheel which may be dressed straight across with a minimum of wastage. The term cylindrical surface as used herein includes a surface defined by the usual geometrical definition. That is, it is a surface which is generated by moving an are or curved line (not necessarily a circular are) along a line transverse to its own plane. This line become the axis of the cylindrical surface. One characteristic of such a cylindrical surface is that it can be developed or unrolled into a plane, as distinguished, for example, from a spherical surface which cannot be so developed.

Another object of the present invention is to provide a method of grinding a cylindrical surface of comparatively small radius by means of a straight face grinding wheel having an effective working width considerably greater than the surface and in which the entire face is utilized during each grinding operation.

A further object of the present invention is to provide apparatus for automatically accomplishing the grinding method of this invention.

A further object of the present invention is to provide ,a mechanico-hydraulic drive system for powering and controlling the apparatus of this invention.

Further objects and advantages of the present invention will be apparent from the following detailed description, with reference to the accompanying drawings in which like reference characters refer to the same parts throughout the several views, and in which:

FIGURE 1 is a side view of the grinding machine of this invention;

FIGURE 2 is a plan view of the machine shown in FIG URE l;

FIGURE 3 is a semi-schematic plan view of a portion of the structure shown in FIGURE 2 on an enlarged :scale illustrating the manner in which the grinding wheel is moved to generate a cylindrical surface on a ledged 1 FIGURE 6 is a sectional view taken along line ti-fi to fully expose its wide working area to the surface to be ground; and

FIGURE 7 is a view in schematic fashion of the mechanico-hydraulic motivator of this invention.

While the disclosed grinding method and apparatus can readily be adapted to grind a curved surface on a variety of workpieces in a variety of environments, for purposes of illustration the invention will be disclosed in relation to the grinding of a relatively small (approximately cylindrical surface on the valve stem-contacting end of an automotive internal combustion engine rocker arm. Such a rocker arm W is shown in FIGURES 3 and 4 fixedly positioned for the grinding operation. The cylindrical surface 19 to be ground is on a ledge which projects laterally from an arm which projects move or less radially from a larger central cylindrical portion and is relatively inaccessible for grinding by ordinary methods and apparatus. The reference character 12 represents the axis of the cylindrical surface. This shows in the drawings as the phantom line 12 in FIGS. 1 and 4 and the point 12 in FIG. 3. The latter is the trace of the axis in the plane of FIG. 3. The workpiece to be ground has a rough surface generally following this cylindrical surface, which in the grinding operation, is accurately finished by the Wheel.

Referring to FIG. 2, the rocker arm workpiece W is fixed during grinding on a rotary indexing table 14 having a plurality of workpiece gripping mechanisms 16 equidistantiy positioned in a circle near the periphery of the table. A single workpiece may be loaded upon and loosely received by one of the gripping mechanisms at a loading station 18, after which the table is indexed to present the workpiece to a locating and gripping station 2% where the workpiece is accurately positioned by means of a rigid abutment 22 on a horizontally swinging arm 24 which also contains a spring-loaded plunger 26. The arm 24 is swung into contact with the loosely supported workpiece to a predetermined location where the abutment 22 accurately positions the surface it) which is to be ground, and the spring-urged plunger 26 may give way as it pivots the face 19 against the abutment 22.

vilh the arm in the desired position, a gripping mechanism (not specifically shown) such as an expanding collet 28 upon which the workpiece has been pivotally positioned is operated to grip the workpiece firmly in the exact position determined by the arm 24. When the workpiece is thus gripped, the arm is retracted and the area 10 to be ground is accurately located with respect to the edge of the table 14. Two more indexing movements of the table bring the workpiece past an idle station 30 and to the grinding station 32, where the table is securely clamped to hold the workpiece securely in a stationary position for the grinding operation. Upon completion of the grinding operation the table may again be indexed to position the-finished workpiece at an unloading station 33.

The grinding wheel used by this invention is of the face grinding type wherein a plane side face 34 between an inner and outer diameter of a cup-shaped wheel 36 is the working face. Such a wheel 36 may be supported by a spindle 38 driven by a pulley 40 through a belt (not shown) from a motor 42. The wheel, wheel spindle, and motor are mounted on a movable housing 44 which both slides and rotates on a horizontal pivot bar 46 (FIG. 1).

The pivot bar 46 is rigidly secured in the upper end 48 of a vertical pivot bar 50 rotatably mounted in a fixed housing 52 on the base 54. An additional strut support 56 extends between the lower end of the pivot bar 5i) and the outer end of the horizontal pivot bar 46. Oscillatory motion of the upright pivot bar 50 about its axis swings-theworking face of the grinding wheel 36 r 3,176,440 r a about the vertical line 12 which is the center line or axis of the cylindrical surface to be ground as well as the center line of the pivot bar 50.

This motion is obtained by means of a double hydraulic motor'associated with houisng .52 and clearlyff shown in FIGURE 5. A gearSS keyed at 60 to the pivot bar 50 meshes with opposed racks 62, formed integral with pistons 66, 68 which reciprocate in opposite. directions in

parallel cylinders

70, 72, respectively, in the pivot bar housing 52. Pressurized 'fluid'admitted to cylinder 70' through connection 74-serves to rotate pivot bar 50 in a counterclockwise direction in.FIGURE-5, as can be understood, and fluid admitted through aconnection 76 to cylinder 72 will rotate the pivot bar 50 oppositely.

This oscillatory motion will, as. seen in FIGURE 3, rotate the working face 34 of the off set grinding wheelthrough an are from the position a't 34' shown-in dashed lines to the position shown in dash-dot lines at 34" about the center line 12 to generate the cylindrical surface on the workpiece W. During this arcuate motion, the working face ofthe wheel is always tangent to the cylindrical sur-' face, and does not extend radially far enough to interfere a connection 112 acting on'theleft-hand face of a piston 114 reciprocable in a cylinder 116 and to which the abut- 'ment member is attached: When it is desired to obtain a further-than ordinary clockwise rotation of wheel head "44 for purposes of dressing" the, grinding wheel, fluid throughjafconnection117 moyesvpiston 114 to the 'left,

' retracting abutment member 110' toallow a longer stroke of piston 86, The amount of retraction of abutment member 119 is governed by another adjustable stop memher 118 which limits the leftwardstroke of pistons 86 and 114. r I

' The oscillating motion ofthe motors in the housing 1 44 which rotate the grinding wheel about-fixed pivot bar is located 'on the dashed radial line 122" may be very working face 34 into contact'with the workpiece.

with the enlarged cylindrical, central portion of the rocker arm workpiece held by the collet 28.

In addition to the arcuate motion about the centerline 12 the rotating grinding wheel of this invention partakes e of another motion during the grinding operation which is in the plane of its working face, and may be, for example, an arcuate motion about the horizontal pivot. bar 46.

This'exposes the entireieifective working face of the wheel to the relatively small surface to be ground, and is accomplished by a second double acting fluid motor in the housing 44, as best seen in FIGURE, 6. p 7

As previously mentioned, the bar 46 is rigidly mounted at the upper portion 48 of the bar 50, and the housing 44 is rotatably mounted about the horizontal bar. Fixedly secured to the horizontal bar 46, as shown in PIC-L6 is a gear 80 engaging opposed racks 82, 84 associated with

pistons

86, 88 reciprocable respectively in parallel cylinders 90, 92.

The weight of the the righthand side of the bar 46 in FIGURE 6 tends to move the housing 44 in a clockwise directionurging upper' piston 86 to the left and lower piston 88'to the right in their respective cylinders. This tendency is counter 46 is schematically illustrated in FIGURE 4 where the fullwidth of the face 34 'of'the grinding wheel 36 is visible adjacent the endof the workpiece W upon which a cylindrical surface is to be ground. With the wheel in a starting position its center- 120 is located on the solid radial line 122. .Motion in' a counterclockwise direction about pivot bar; 46 to a position in' which the wheel center 120' i .is accomplished within a'time equal to the time required for generating thecylindrical surface from position 34' to 34 in FIGURE 3. The position of the axis of bar 46,

s the trace of which'in FIG. {Us at the intersection of lines grinding wheel, spindle, and motor .on

122,122, is illustrative of-any linelying in a plane which plane is perpendicularto the line 12,.which latter is the center of the cylindrical surfaceto be ground. 7

Dressing apparatus 150 for the grinding wheel is fixedly located with respect to the" horizontal pivot bar 46 and theupper portion 48 or the vertical pivot bar 50. During ordinarymass production grinding, the wheel may grind a large number of workpieces before dressing of the wheel is required. When dressing: is required, the'adjustable abutment member 110 isretracted by means of pressuracted to some extent by a counter balancing fluid spring mechanism 94' on the left-hand end of'the lower portion of the fluid motor. a The hydraulic counter balancing device comprises a relatively large piston 96'oontinu'ally' izing fluid through connection117, and the wheel is allowed to pivot clockwise until its center reaches a point 152 (FIGURE 4) on the dash-double-dot radial line 154,

urged to the 'left end of a cylinder 98 by ipressurizedl fluid from a source R0, to be described, admitted 7 through a connection 100. The rod 102 of piston 96 is secured by a bolt ,104 or other siutable means to the;

smaller arealpiston' 88'to continually bias the housing 44 in a counterclockwise" direction about pivot bar 46.]

Motionin this direction is limited by an adjustable abutment means 106 threaded in' the, left-handend of the cylinder 98. V 7

When it is desired to rotate" the housing 44- andits grinding wheel'34 in a counterclockwise direction, the

biasing power of the mechanism 94 is amplified by, ad-j,

mitting fluid under pressure through a connection 108 to the upper cylinder to move piston86 to the right until the'lower piston assembly contacts the abutment 106. 1 Clockwise motion of the housing .44, and wheel-36 about the pivotibar 46 is also limited byan adjustable abutment member 110 which halts the leftward. strokeofpiston 86.

For purposes .of dressing the'wheel'36,"in a manner later to be described, the abutment member 110 may "be retracted to the left (to the position shown, in phantom ment of Y the grinding wheel.

pressure of fluid from the source R0 admitted through outline) to allow more, than the ordinary clockwise move- 7 i V The'abutment member 110 7 is ordinarily held in .its normal, extended position by the v a distancesufiicient to traversethe face of the wheel across the point of the dressing tool. This method of dressing, often referred togas diamond-sizing, is-a quick and extremely accurate manner of dressing a straight face on a wheel with a minimum of grit wastage.

Y Prior to each clockwise dip of the wheel for dressing purposes, the housing 44 isadvanced longitudinally along the horizontal pivot barf46 toward theworkpiece, preferably by an automatic, fluid motor actuated, ratchet fed 156 on theouter end of the'bar 46; f V

For the purpose of' operatin'g the" various operating lead screw device indicated schematically in FIG. 1 at 'means for the table, the grinding-head, and the dressing operation inzthe" proper time ';relationship, are two *mechanico-hydraulic programming units provided for producing a cycle. of ,coordinatedmovement, illustrated diagrammatically in FIGURE 7. "Each system may be constructed as a self-contained unithaving its own housing; not illustrated, which may be positioned at any con-' 7 venient location on or adjacent the machine and connected to the various hydraulic cylinders by suitable flexible piping. One programming. unit powers and controls movement of the grindingpwheel during the dressing operation, and the other or main unit controls the'loading, orienting, and-unloading of workpieces on the table astwell as indexing motion of the table and the 'movement motor 272 for engaging the brake.

of the grinding wheel during regular grinding operations. The two units operate in turn under the control of a counting device.

The cam-driven liquid column type motion transfer unit 202 for dressing is shown in the upper left portion of FIGURE 7. It includes a prime mover 2% driving a belt 266 which rotates a worm shaft 298. Shaft 208 runs through a hydraulic clutch 210 and has mounted thereon worm 212 for rotating a cam shaft 214 by means of a Worm wheel 216. Fluid for the hydraulic clutch 210 is pumped from reservoir 220 by a pump 222 and through a spring loaded, solenoid actuated valve 224. When the valve is in its spring urged rest position (designated by the unhatched rectangle with the single head flow-direction arrow), fluid will be allowed to flow back to the reservoir through line 218 from clutch 2317i), thus disengaging the clutch and stopping cam shaft 214. When the valve 224 is in its solenoid actuated position (designated by the cross-hatched rectangle with the double head flow direction arrow), pressurized fluid will be allowed to flow from the pump 222 to the clutch 210, thus engaging the clutch and driving cam shaft 214.

Cam shaft 214 has two pulsator or transmitter sections each comprising a rotary cam 226, the follower of which operates a piston 228 reciprocable in a cylinder 234). Each pulsator forms part of a liquid column type motion transfer device which further includes a liquid column 232 and a low pressure reservoir 234. The operation of this system will be fully apparent from the description of the main motivator unit 200, which follows.

The main mechanico-hydraulic drive unit 206 for driving the machine while grinding comprises a master camshaft 236, in the lower right of FIGURE 7, carrying a plurality of cams 238 (only three shown), the followers of which operate the transmitter pistons 24 0, each of which forms part of a liquid column type motion transfer device of which there are three shown in the diagram of FIGURE 7. Each piston reciprocates in a cylinder 242 having a head 244 which contains a suitable inlet replenishing check valve 293 and a high pressure relief valve 295 both of which communicate With a low pres- I sure oil reservoir 296 preferably formed in a housing enclosing each drive unit.

For turning the camshaft 236, a motor 246 drives an input shaft 248 of a two-speed transmission through a belt drive 250. The input shaft 248 drives a pinion 252 and also the input member of a hydraulically-engaged, spring-released clutch 254. Pinion 252 drives a gear 256 secured to a countershaft 258 which carries a pinion 260 at its opposite end. Pinion 26f) drives a gear 262 and therewith constitutes a set of change speed gears. Gear 262 drives the input member of a second hydraulicallyengaged, spring-released clutch 264. The driven members of clutches 254 and 264 are secured to the opposite ends of a shaft 266, having a worm 268 thereon and a brake drum 27%. The latter has a spring-biased hydraulic Worm 268 drives a worm wheel 274 secured to the master camshaft 236.

For the purpose of automatically controlling the start ing, stopping, and speed of the transmission, there is provided a hydraulic control pump 2'76 driven from gear 262,- which may circulate a body of oil contained in the housing surrounding the transmission. The pump 276 may deliver to a combined accumulator and relief valve comprising a spring loaded piston 27S and also supplies oil to a bank of control valves 28%), 282 and 284. In the diagrams each valve is shown as a two-position valve, spring-biased to the normal position illustrated in which the connections shown in the cross-hatched rectangles are established. Single-headed arrows are used to indicate flow at reservoir pressure and double-headed arrows to indicate flow at pump delivery pressure. Each of the valves, when shifted, establishes the connections shown in the unhatched rectangles immediately below the hatched rectangles.

Valve 280 is arranged to be shifted by a solenoid 286, which may also actuate an open-close dumping valve 287.

Valves

282 and 284 are arranged to be shifted by the adjustable cams 288 and 290, respectively, which are positioned on camshaft 236. In addition, the valve 232 has a hydraulic holding cylinder 292 which holds the valve 282 in its shifted position until it is released by the shifting of valve 284. Valve 280 in the position shown delivers pressure fluid to engage the brake 272 and also exhausts fluid to release the low speed clutch 264. When shifted, valve 280 exhausts fluid to release brake 272 and supplies pressure fluid to engage the low speed clutch 264, subject, however, to a conjoint control by the valve 282.

The latter valve, in the position illustrated, exhausts fluid to release the high speed clutch 254 and places the low speed clutch 264 under the control of valve 280. In its shifted position, valve 282, provided valve 280 has been shifted, delivers pressure fluid to engage high speed clutch 254 and exhausts fluid to release low speed clutch 264-. As previously explained, the valve 284 is merely a reset valve for bypassing the holding cylinder 292 to permit valve 282 to return to its spring biased position.

Thus, energization of solenoid 236 will start the camshaft rotating at slow speed. Thereafter, the cam 288 will shift the transmission to drive the camshaft at high speed, and still later the cam 290 will again shift the transmission to slow speed. So long as the solenoid 286 remains energized, the camshaft 236 Will continue to rotate, first at a slow speed and then at a high speed during each revolution, controlling its own speed changes by operation of the cams 238 and 290.

Tie camshaft 236 as previously mentioned drives a number of cam operated hydraulic pulsator sections; Each section may comprise units duplicating the single acting pulsating cylinder 242, the head 244 of which contains the replenishing check valve 293 and the spring closed relief valve 295. All the replenishing and relief valves are connected to a common oil reservoir 2% formed in the housing of the unit. The reservoir 2% is preferably subjected to a low, super-atmospheric pressure by a body of compressed air or other pressure maintaining arrangements. Check valves 293 allow flow from the reservoir 2% to the cylinder 242, while relief valves 295 allow flow oppositely when the cylinder pressure exceeds a certain value. Thus each of the pairs of

valves

293 and 295 may be referred to as a balancing valve and serve to balance the volume of fluid in each of the liquid column sections, as will be later described. The pulsator sections are connected by closed liquid column lines 298 with the two work performing motors for moving the grinding head.

In order to insure proper synchronization of the driving and driven elements of each pulsator section, it is desirable to provide slightly more fluid displacement in the driving or transmitting-elements 240-242 than is present in their respective fluid motors at the opposite end of the liquid column line. Thus at the end of each advancing stroke of the transmitter piston 246, a small amount of fluid will be discharged to reservoir 296 through its relief valve 295. This amount plus any amount lost by leakage will be returned to the liquid column at the end of the return stroke by the operation of the replenishing valve 293. I

In FIGURE 7 there are shown several circles marked R0 connected to the end of some of the motive cylinders opposite the liquid column connections. These symbols designate the return oil connections by means of which a pulsator system may be hydraulically biased, as previously mentioned, so as to maintain the follower in close contact with the cam as the falling portion of the cam contour recedes from the follower.

The contours of the

individual cams

226 and 238 are likewise not illustrated in specific detail since they may be formed in accordance with the usual practice to cause the machine. Likewise the speed ratio between the high and low speeds of the cam shaft 236, and the duration of the high speed portion of the cycle, may be selected as desired through use of the appropriate change gears 260-262 and through the adjustment of the cams 208 and 290, if desired. Of course, the two speed feature of the transmission may be omitted andthe .high speed clutch 254, the cams 288 and 290 andthe valves 28 2 and 284 eliminated.

. The units 202 and 200 for powering and controlling the dressingoperation and'the grinding mechanism, re-. spectively,are interconnected by means of a known electrical counting device 300 for beginning the dressing cycle immediately upon completion of the feeding of a predetermined number of workpieces and to stop the dresser motivator and commence .grindingthe instant the dressing operation is complete. The counter 300 contains: a conventional ratchet actuating solenoid, or count coil, 302 and a clutch reset solenoid, or clutch coil, 304. In addition,.the counter contains a switch for making contact between connections 305 and306 while breaking contact between connections 305 and 308'in one position, and vice-versa in the other position. Current for powering the circuitry of FIGURE 7 is provided by lines 310. I

When the main unit 200 is operating and workpieces are being successively ground by the wheel, a cam 312 closes contacts 314 once on each revolution of cam shaft the outer diameter of the working 'face'into contact with one edge of the cylindrical surfaceto be ground. At this instant the counterclockwise motion about the bar'46 is slowed by thecam and the transmission to a suitable speed, and arcuate motionof the wheel about the center line 12 to generate the cylindrical surface '10 is commenced by cam moved liquidconnector 76. Both arcuate motionsthen proceed simultaneously-the motion about vertical pivot bar 50 generating the cylindrical contour and-the arcuate motion about, bar 46 traversing the wheel across the work. vBoth arcuate motions are accomplished with a controlled speed designed so that they are completed simultaneously, afterwhich the grinding oper-' ationis completed and the wheelEis in the position indicated in solid lines in FIGURE 2. The arcuate motion about the, center of bar 46 is illustrative of any suitable traversing motion by which the flat face ofthe. wheel across the surface being ground by the rotating I tio n shown in phantom outline in FIGURE 2. The above operation is repeated by successive revolutions of cam 236 at the end of a cycle. On each momentary closing 2 shaft 236 until the wheel needs dressing, as determined by the counter 300. I

-;Then, the main motivator camshaft 236'is stopped and the shaft 214 is rotated. First, the wheel is advanced by a liquid column pulsator'section under control'of one its ordinary starting'fposition (120 to,152, FIGURE v4) are open and 306 areclosed, providing power for the f solenoid 286 on valve 280, .287. When a preset number of revolutionsof cam shaft 236 (determined by the type of workpiece, etc.) have been recorded in'the counter,

the counter switch is thrownto the position in which contacts 305 and 306are opened and 305 and 308 closed. The instant contacts 305 and: 306 are opened, the brake 270, 272 isiappliedand the clutches 254 and ,264 are'.

disengaged, thus stopping cam shaft 2 36.

Closing or contacts 305 and 30s closes solenoid sew-f.

' ated switch 320 for starting the pnme mover 204 of the a valve 224 toenga'ge hydraulic clutch 210, permittingcam shaft 214 tobe-rotated by prime mover 204.; Thus imdresser drive unit, and also actuates solenoidoperated mediately upon the'counter. recording a"pre'-set number.

in a clockwise direction about bar46 to traverse the diamond dressing apparatus. This is accomplished by backing off the limit stop v110by .moving piston. 114

. through liquid column'c'onnector 117 under control of the other of thecarns 226; With 'the wheel satisfactorily dressed andgretumed to the normal starting position, grinding operations are immediately resumed by stopping shaft 21 4 upon completion of its revolutionand resuming rotation ofcam shaft 236 the manner previously described. 1 7 While -the above described embodiment 'constitutesa preferred mode of carrying out this invention, many other formsmight be-adopted within the scope of the] actual of workpiece grinding cycles, that'mcchanism is idled 7 and the dressing motivator is actuated to begin the dressn y l -x 7 When the dressing cycle has beencompleted, and

before cam shaft 214 has completed: its revolution, a

cam 322 'mornentarily closes contactsf324 and pulses current through the counters clutch coil 304 which resets the counter and moves the counters switch to break contact 8.13398 and again makecontacts 305 and :306'. ,{As

current stops flowing through contacts 305 and 308, solenoid switch 320 will shut off prime move'rj204andf the spring of valve 224 willreturn it to its-rest position disengaginghydraulic clutch; 210, thus allowing camshaft 214 to quickly coast to astop, and the peaked'lobe Q to the surface tobe ground, moving the-'wheel face rapidly of cam 322 to pass justbeyond thefollower. .Closingof Y contacts305 and 306 againgstarts themain s5 by the. table invention-which isvariously claimedasr' 1'. The; method ofgrinding on'a workpiece a cylindrical surface about agiven axis comprising the steps of rigidly locating the workpiece 'adjacenta face grinding wheel, continuously rotating the wheel about its axis, moving the wheel face into grinding contactv with the workpiece, and then pivoting the axis of the wheel about the cylindrical axis'to'move the wheel in an arcuate path about the'giyen cylindrical axis to generate the cylindrical surface while simultaneously moving the wheel in the plane of its face'to expose an extendedi'area of thewheel face to the workpiece.

the workpiece adjacent a face grinding wheel, "continu- .ously rotating the wheel about its axis with its'face tangent from a starting position into grinding contact with the workpiece, rnoving the wheel face. slowly in an arcabout the given line to generate the cylindrical surface while simultaneously moving'the wheel 'face; in another are trolled by cam actuated pulsator sections'on main shaft 1 1 236. Immediately, the grinding wheel pivots rapidly for a short distance, under the influence ofa steep cam rise pulsing fluid' through liquid column 103, in a counter clockwise direction about the horizontal bar 46 to bring about 'a line which remains in a plane which is normal to the given line at aspeedsufficient-to expose theentire effective width of the wheel face to the workpiece during the time" required to generate the-surface, and rapidly j moving the wheel face back to thestarting position out of contact withthe workpiece. 7 I

3. Themethod ofgrinding a cylindrical surface about a given line on a workpiececomprising the steps of fixing the workpiece adjacent a face grinding wheel, continuously rotating the wheel about its axis, moving the wheel face into grinding contact with the workpiece, moving the wheel in a first are about the given line to generate the cylindrical surface while simultaneously moving the wheel in a second arc between a start and a finish position to expose the entire width of the wheel face to the workpiece, repeating this operation on a preselected number of workpieces and then moving the wheel in the second are beyond the start position and into contact with a fixedly positioned dressing tool to re-face the wheel.

4. In a grinding machine, apparatus for grinding a convex curved surface on a workpiece comprising gripping mechanism for securely clamping a workpiece, a face grinding wheel rotating with its face tangent to the surface to be ground, means for moving the wheel face along a first path corresponding to the surface to be ground and with the wheel face tangent to the surface, means for moving the wheel along a second path in the plane of the wheel face and through a distance at least as great as the effective width of the face to shift the point of grinding contact across the face, and control apparatus connected to operate the two moving means together for grinding the surface utilizing an extended area of the wheel face.

5. In a grinding machine, apparatus for grinding a cylindrical surface about a given line on a workpiece comprising gripping mechanism for fixedly locating a workpiece, a face grinding wheel rotating with its face tangent to the cylindrical surface to be ground, means for moving the Wheel in a first arc about the given line to generate the cylindrical surface, means for moving the wheel in a second are about a line which remains in a plane which is normal to the given line and through a distance greater than the effective width of the wheel face to shift the line of grinding contact across the face, and control apparatus connected to cause the two moving means to operate together whereby the rotating wheel grinds the cylindrical surface on a workpiece utilizing the full effective width of the wheel face.

6. In a grinding machine, apparatus for generating a cylindrical surface about a given line comprising a grinding wheel rotating with its working face tangent to the cylindrical surface to be generated, means for moving the wheel in an arcuate path about the given line to generate the cylindrical surface, means for moving the wheel in another path in which the wheel remains tangent to the cylindrical surface and moves through a distance greater than the effective width of the wheel face to shift the point of tangency across the face, and control apparatus for the two moving means connected to operate them in overlapping timed sequence whereby the rotating wheel undergoes motion tangent to the cylindrical surface While generating the surface.

7. A dial type grinding machine comprising a base, a rotary index table mounted for step-by-step rotation on the base, a plurality of workpiece holders mounted in equally spaced positions circumferentially of the table, means for indexing the table in intermittent steps, a plurality of operating stations on the base and distributed circumferentially around the table including stations for loading, positioning, grinding and unloading workpieces successively, means at the grinding station connected to traverse a rotary grinding wheel across a workpiece perpendicularly to the axis of grinding wheel rotation and additional cooperating means at the grinding station for simultaneously shifting the grinding wheel in an acrcuate path to grind an arcuate face on the workpiece while utilizing an extended area of the wheel face.

8. A dial type grinding machine comprising a base, a

table mounted for rotary motion on the base, means connected to impart step-by-step motion to the table, a plurality of workpiece holders mounted in equally spaced positions circumferentially of the table, a plurality of operating stations on the base distributed circumferentially around the table including stations comprising means for loading, means for positioning, means for grinding and means for unloading workpieces successively, the means at the grinding station including apparatus connected to transverse a rotating grinding Wheel across a workpiece in the plane in which the wheel rotates and additional cooperating apparatus for simultaneously moving the grinding wheel in an arcuate path to generate a convex surface on a workpiece, a plurality of fluid motors connected to actuate all of the said means, and a mechanico-hydraulic motivator comprising a common camshaft and a plurality of rotary cam powered and controlled liquid column type motion transfer devices connected to operate each of the fluid motors through a coordinated program of movements.

9. A grinding machine for grinding a curved ledge on a workpiece having a raised portion adjacent the ledge and extending radially outward of the projected curved surface of the ledge comprising a base, a grinding wheel mounting having a first pivot about which the grinding wheel may be oscillated to generate the curved surface and a second pivot about which the grinding wheel may be oscillated in a plane containing its working face, a wheel spindle having a face grinding wheel mounted for rotation about an axis parallel to a radius of the curved surface and beyond the end of the first pivot, and means for mounting a workpiece opposite the wheel face and also beyond and in line with the first pivot whereby a curved ledge surface may be ground without interference from the raised portion of the work.

10. In an automatic grinding machine, means for generating a small curved surface on a workpiece having a raised portion laterally adjacent and extending outwardly of the projected curved surface comprising a base, an index member mounted for step-by-step shifting motion on the base, means on the member for carrying a plurality of workpieces during grinding operation, a loading station on the base including means for supplying workpieces individually to the carrying means on the index member, an unloading station on the base including means for removing workpieces individually from the carrying means on the index member, and a grinding station on the base including a rotary grinding wheel, means connected to shift the wheel along a first path in one direction to generate a curved surface on a workpiece and means connected to simultaneously shift the wheel along a second path in one direction to utilize an extended area of the wheel face on the surface, and control means connected to operate the shifting means at the grinding station simultaneously with the supplying means and removing means at the loading and unloading stations and to shift the index member simultaneously with shifting of the grinding wheel in the other direction along the first and second paths.

References Cited by the Examiner UNITED STATES PATENTS 2,544,604 3/51 Mader 51-55 2,821,813 2/58 Degler 51-105 X 2,865,302 12/58 Amiet 51219 2,922,258 l/60 Bass 5155 J. SPENCER OVERHOLSER, Primary Examiner. JOHN C. CHRISTIE, Examiner.

Claims

1. THE METHOD OF GRINDING ON A WORKPIECE A CYLINDRICAL SURFACE ABOUT A GIVEN AXIS COMPRISING THE STEPS OF RIGIDLY LOCATING THE WORKPIECE ADJACENT A FACE GRINDING WHEEL, CONTINUOUSLY ROTATING THE WHEEL ABOUT ITS AXIS, MOVING THE WHEEL FACE INTO GRINDING CONTACT WITH THE WORKPIECE, AND THEN PIVOTING THE AXIS OF THE WHEEL ABOUT