US2778163A - Valve grinding machine - Google Patents

Description

Filed Nov. 29, 1954 C. G. FLYGARE VALVE GRINDING MACHINE CARL BY 5 Sheets-Sheet l INVENTOR.

ATTURNE Y C. G. FLYGARE VALVE GRINDING MACHINE I Jan. 22, 1957 Filed Nov 29, 195.4

'5 SheetsSheet 2 INVENTOR. CA R L. G. F

BY MU.eJ-an ATTDR'NEY C. G. FLYGARE VALVE GRINDING MACHINE Jan. 22, 1957 Filed Nov. 29, 1954 5 Sheets-Sheet 3 hm J \mm @W NW VW M NQ bmw V. WWW Lb k y mmw n 0 mm m6 mm M x & 2 m 0 J j Vb mm mw m fi Egg? Mm :3 im 9v aw? F N n \N@ \%m m m Wm Rwq G 8 Mm R\ INVENTOR EARL [3. FLYGARE BY v ATTUFNEY Jan. 22, 1957 c. s. FLYGARE 'YALVE GRINDING MACHINE 5 Sheets-Sheet 4 Filed Nov. 29, 1954 bin Vb INVENTOR. CARL G.FLYGAR'E ATTORNEY A Jr .Fan. 22, 195? c. G. 'FLYGARE VALVE GRINDING MACHINE 5 Sheets-Sheet 5 Filed Nov. 29, 1954 lil? INVEN TOR.

CARI. G". FLYG'AR'E ATTUE'NEY 2,778,163 VALVE GRINDING MACHINE Carl G. Flygare, Worcester, Mass, assignor to Norton Company, Worcester, Mass, a corporation of Massachusetts Application November 29, 1954, Serial No. 471,632 10 Claims. (Cl. 51-3) This invention relates to grinding machine, and more particularly to a valve grinding machine.

One object of the invention is to provide a simple and thoroughly practical valve grinding machine. Another object is to provide a grinding machine having a shaped grinding wheel which is arranged 'so that an axial feeding movement of the grinding wheel serves to grind a frusto-conical face on the valve being ground. Another object is to provide a grinding machine having a grinding wheel provided m'th a frusto-conical and an adjacent cylindrical face whereby an axial feeding movement of the grinding wheel serves to grind a frusto-conical face on the valve being ground. Another object of the invention is to provide a grinding wheel having a taper and a cylindrical face which is arranged so that an axial feeding movement of the grinding wheel serves to grind a cylindrical face on a valve being ground. Another object is to provide a grinding machine having a shaped grinding wheel which is arranged so that an axial feeding movement of the grinding wheel serves to grind a cylindrical face on the valve after which a swivelling movement of the grinding wheel serves to grind a bevelled face adjacent to the cylindrical portion on the valve. Another object is to provide a grinding machine having a pair of grinding wheels alranged on opposite sides of a valve to be ground both of which are shaped so that a simultaneous axial feeding movement of the wheels serves to grinda frusto-conical valve face and an adjacent cylindrical face thereon after which a swivelling movement of one of the wheels serves to grind a bevelled face adjacent to the cylindrical face. Another object is to provide means actuated by and in timed relation with the axial feeding movement of one of the grinding wheels automatically to initiate a swivelling movement thereof so that the cylindrical face is first ground after which the wheel swivels automatically to grind an adjacent bevelled face. Other objects will be in part obvious or in part pointed out hereinafter.

In the accompanying drawings in which is shown one of various possible embodiments of the mechanical features of the invention, A

Fig. 1 is a plan view of the improved valve grinding machine,

Fig. 2 is a side elevation of the machine,

Fig. 3 is a fragmentary vertical sectional view, on an enlarged scale, taken approximately on the line 3-3 of Fig. 1, through one of the grinding wheel slides;

Fig. 4 is a fragmentary vertical sectional view, taken approximately on the line 4-4 of Fig. 3;

Fig. 5 is a fragmentary horizontal view, on an enlarged scale, taken approximately on the line 55 of Fig. 2, through one of the wheel feeding mechanisms;

Fig. 6 is a fragmentary vertical sectional view, on an enlarged scale, taken approximately on the line 66 of Fig. 1, through the work supporting spindle;

Fig. 7 is a fragmentary vertical sectional view, on an type wheel enlarged scale, taken approximately on the line 7-7 of Fig. 2, through the work head traversing and positioning mechanism;

Fig. 8 is a diagrammatic view showing the relative positions of the grinding wheels and the faces of the work piece to be ground; and

Fig. 9 is a combined electric and hydraulic diagram of the actuating and control mechanisms of the machine.

on an automotive engine valve. mat cally in Fig. 8 a valve 10 is ing 40 for supporting the grinding wheel 17. ing wheel 17 is partially surrounded by a conventional guard 41. A multiple V-groove pulley 42 is mounted on the right hand end of the wheel spindle 39 and is drivingly connected by multiple V-belts 43 tip le V-groove pulley (not shown) the upper surface of. the wheel slide 32.

A suitable feeding mechanism is provided for adjusting the Wheel slide 32 to position the operative faces of the grinding wheel 17 into the desired relationship with the work piece being ground. This mechanism may comprise a manually operable feed wheel 50 which is operatively connected to rotate a gear 51 (Fig. 2) mounted on the right hand end of a rotatable shaft 52. The left hand end of the shaft 52 is provided with a bevel gear 53 which meshes with a bevel gear 54 which is rotatably journalled within the wheel slide base 85 of the machine and is slidably keyed to a cylindrical portion 55 of a rotatable feed screw 56. The feed screw 56 meshes with or engages a half-nut. 57 depending from the underside ofthe wheel slide 32. It will be readily apparent from the foregoing disclosure that a rotary motion of the feed wheel 50 will be imparted through the mechanism above described to cause a transverse movement of the wheel slide 32, that is, in a direction normal to the axis of the wheel spindle 39; This feeding mechanism is utilized in the present machine merely for positioning the grinding wheel 17 and for compensating for wheel wear thereon.

The axial grinding feed of the wheel 1'7 for grinding the cylindrical face 12 of the Valve 1'8 is accomplished by an axial movement of the grinding Wheel spindle 3-9.

A hydraulically operated mechanism is provided for axially moving the spindle 39 which preferably comprises acylinder 66 (Fig. 3') which contains a slidably mounted piston 61 fixedly mounted on the right hand end of a piston rod 62. The piston rod 62 is opcratively connected to a vertically arranged stud 63 carried by a rock arm '64. The rock arm 64 ispivotally supported by a shaft 65 within the wheel slide 32. The rock arm 64 is provided with a yoked shaped' portion having a pair of diametrically arranged studs 66 and 67 which engage apertures ina thrust ring- 68which rides between a thrust surface 6% and a thrust collar 70 carried by the wheel spindle 39 (Fig. 3).

When fluid under pressure is'passed' through a pipe 71 into a cylinder chamber 72, the piston 61 will be moved toward the leftto rock the rock arm 64 in a clockwise direction to axially move the wheel spindle 39 toward the left so that faces 13 and 19' of the grinding wheel 17 will grind the cylindrical face 12 of the valve to the desired and predetermined extent. During this movement oi the piston 61, fluid within a cylinder chamber 73 may exhaust through a pipe 7d, through a throttle valve 75 which controls the rate of movement of the piston 6 toward the left (Fig. 9). A throttle valve 76 is provided in the pipe line. '71 which serves to control the rate of flow of fluid through the pipe 71 when passed to or exhausted from the cylinder chamber 72.; A check valve 77 is provided in the pipe line 74 which'isarranged so that fluid. passing through a pipe 78 into the cylinder chamber 73 may lay-pass the throttle valve 75"and thereby move the piston '61 toward the right at a rate controlled by the-throttle valve. 76.

The movement of the wheel spindle 39 toward the left continues until the face 19 of the grinding wheel 17 has ground the cylindrical face 12 of the valve it! to the desired and predetermined extent at which time the stud 63 engages an adjustably mounted stop screw 30 which is supported by a boss 81 projecting upwardly from the wheel slide 32. The piston rod 62; is provided with a head portion 32 which is operatively connected by an elongated slot. 32a with the upper end of the stud 63. The head 82 is provided with an upwardly projecting bracket 83 carrying an adjustably mounted stop screw 84 which is arranged to engage the actuating plunger of a normally closed limit switch LS1.

A swivelling mechanism is provided. for swivelling the axis of the wheel spindle 39 in a horizontal plane so that the operative faces 26 and 21 on the grinding wheel 17 will grind the frusto-conical face 13 on: the valve lit}. The wheel slide 32. is preferably supported on a wheel slide base 85 which is arranged to swivei about the axis of a stud 85a on the machine base 30 (Fig. 1). A hydraulically operated mechanism is provided for swivelling the wheel slide base 85 comprising a cylinder 86 containing a slidably mounted piston 87. The cylinder 86 is fixedly mounted on the base 3%. The piston 37 is operatively connected to a piston rod 83, the left hand end of which is connected by a stud 39 with a pair of spaced links 9t. The links 9% are connected by a stud 91 with a bracket 92 which is fixedly mounted on the rear of-the wheel-slide base 85 An adjustably mounted stop screw 93 carried throttle' valves ltlil'an'd res the rate by a. bracket 94 fastened to the base 30 of the machine serves to limit the movement of the piston 87 toward the left.

The piston rod 88 extends toward the right and is arranged in the path of an adjustably mounted stop screw 95 carried by a bracket 96 fastened to the base 30 of the machine. A piston type control valve 97 is provided for controlling the'admission to and exhaust of fluid from the cylinder 86. The valve 97 is normally held in a left hand end position by a compression spring 98. A solenoid S1 is provided for shifting the valve 97- toward the right into a reverse position. In the position of the valve 97 (Fig. 9), fluid under pressure passing through apipe 99 passes through a throttle valve 1% and also through a check valve 1'31, through a pipe 192 into the cylinder chamber 1% to move the piston 57 toward the left to shift the bracket ilz'linto engagement with the stop screw 93 to maintain the wheel slide in a normal position with the axis of the wheel spindle 39 substantially parallel to the axis of the work piece being ground. During this movement of the piston 87 toward the left fluid within a cylinder chamber 1% may exhaust through a pipe 195, through a throttle valve 1G6 and through a pipe 107. A check valve 103' is provided between the pipes 105 and 1M so that when fluid under pressure is passed through the pipe 107, it may by-pass through the throttle valve Hi6 and also through the check valve 108. During this movement th-e throttle valve 1% will' control the rate of movement of the piston 87 toward the right. The throttle valve 1% serves to control the rate of movement of the piston 87 toward the left. "it will be readily apparent from the foregoing-disclosure that bymanipulation of the of movement of the swivelling of thewheel slid'eb'a'se'SS may beind'epend'ently controlled in both directions.

As illustrated in Fig. 9, the position with the grinding wheel valve 97 is shown in a 17 positioned for grinding the cylindrical face 12 on the valve 10. During the movement of the wheel spindle 39 toward the left, as it aproaches the left hand end of its stroke the stop screw 84 engages the actuating. plunger of the limit switch LS1 to close the contacts therein so as to energize the solenoid SI thereby shiftin'g'the' valve 97 toward the right swivelling the wheel slide so that fluid under pressure will be passed through the pipe 107, through the throttle valve 166 and the check valve 108, through the pipe into the cylinder chamher 164 to move the piston 87' toward the right thereby direction to shift the grinding wheel 17' from the full line position (Fig. 8) into the broken line position 17a, during which movement the operative faces 29 and'Z'lon the grinding wheel 17 will grind the frusto-conical' face 13 to the desired and predetermined extent. The swivelling movement of the wheel slide base in a counterclockwise direction continues untilthe piston rod 88 engages the stop screw 95.

A fluid pressure system is provided for supplying fluid under pressure-to thevarious mechanisms of the machine comprising a motor driven fluid pump 1T0" which draws fluid through a pipe 111 from a reservoir 112 and'pa'sses fluid under pressure through a pipe 113 to the various mechanisms of themachine. Apressurc relief valve 114 is'provided in the pipe line 113' t'o'fac'ilitate"by-passing excess fluid under pressure to the reservoir 11250 as to maintain the d es'ired op'erati-ng pressure withinthe system.

The wheel slide 31 is' similarly supported on a V-way and a flat way (notshown formed onthe upper surface of a wheel: slide base 122 which" is fiitedly'rnounted on the base 30 of the machine. The wheelslide 31 is provided with a rotatablewheel spindle 123 for supportingthegrinding wheel 14; The spindle-1 23 is driven by an: electric motor 114 mounted on the upper surface of the wheel slide= 31. A belt drive the same asthat described in co'nnection with wheel slide 32 is provided within-a-belt: guard- (.Fig; I to transnrit- .powe'r 'frorn the motor 124 to the wheel spindle 123.

base 85' in a counter-clockwise A feeding mechanism is provided for the wheel slide 31*which is identical in construction to that previously described in connection with the wheel slide 32 and comprising a manually operable feed wheel 126 which is connected to rotate a gear 127 carried by a rotatable shaft 128. The shaft 128 is provided with a bevel gear 129 which meshes with a bevel gear 130 which is operatively connected to rotate a feed screw 131. The feed screw 131 meshes with a half-nut 132 depending from the underside of the wheel slide 31. It will be readily apparent from the foregoing disclosure that manual actuation of said wheel 126 will be transmitted through the mechanism just described to adjust the position of the wheel slide 31 relative to the base 30. This mechanism is utilized in the present case merely for the purpose of positioning the wheel 14 in setting up the machine and to facilitate compensation for wheel wear.

A hydraulically operated mechanism is provided for moving the wheel spindle 123 axially to impart a grinding feed to the Wheel 14 so that the tapered face 15 first grinds the face 11 of the valve after which the face 16 completes the grinding to the desired size. This hydraulically operated mechanism comprises a cylinder 135 which contains a slidably mounted piston 136. The piston 136 is connected to the left hand end of a piston rod 137 (Fig. 9). The piston rod 137 is provided with a head 138 at its right hand end having a transversely extending slot 139 which straddles a stud 140. The stud 140 is mounted on a rock arm 141 which is pivotally supported by a stud 142 within the wheel slide 31. The rock arm 141 is provided with a yoked portion having diametrically opposed studs 143 to operatively connect the arm 141' to a thrust collar 144 by means of which the swinging movement of the arm 141 may be transmitted to produce an axial feeding movement of the wheel spindle 123. An adjustably mounted stop screw 145 carried by an upwardly projecting boss 146 on the wheel slide 31 is arranged to engage the right hand end face of the head 138 positively to limit the movement of the piston 136 toward the right. When fluid under pressure is passed through the pipe 78, it may pass through a throttle valve 147 and also through a check valve 148 into a cylinder chamber 149 to move the piston 136 together with the Wheel spindle 123 toward the left into an initial position. During movement of the piston 136 toward the left fluid Within a cylinder chamber 150 may exhaust through a pipe 151, through a throttle valve 152 into the pipe 71. The valve 152 serves to control the exhaust of fluid from the cylinder chamber 150 and thereby to control the rate of movement of the piston 136 toward the left.

When it is desired to start a grinding feed of the wheel 14, fluid under pressure is passed through the pipe 151 into the cylinder chamber 150 to cause the piston 136 to move toward the right thereby imparting an axial movement to the wheel spindle 123 toward the right so that he frusto-conical face of he wheel moves into grinding engagement with face 11 which continues until the cylindrical face 16 moves into engagement with the face 11 of the valve 10 to grind the same to the desired and predetermined extent. During this movement of the piston 136 toward the right fluid within the cylinder chamber 149 may exhaust through a pipe 153, through the throttle valve 147 into the pipe 78. In this case the check valve 148 closes and the throttle valve 147 controls the rate of axial grinding feed of the wheel spindle 123.

A piston type control valve 160 is provided for simultaneously controlling the passage of fluid to and exhaust of fluid from the cylinders 60 and 135. The valve 160 is normally held in a right hand end position by a compression spring 162. A solenoid S2 is provided which when energized serves to shift the control valve to the left thereby reversing the flow of fluid under pressure to the cylinders 60 and 135.

A longitudinally movable work supporting carriage 170 is mounted on a dove-tailed slideway 171 formed on the I mounted on a rotatable shaft 173 (Fig. 7). The right hand end of the shaft 173 is provided with a gear 174 which meshes with a rack'bar 175 depending from the underside of the carriage 170.

The carriage 170 serves as a support for a rotatable work spindle 176 (Fig. 6) which is supported by a pair of spaced anti-friction bearings 177 and 178. An electric motor 1.80 supported on the carriage 170 is connected by.

a belt drive 131 with a back shaft 182 having a pulley 183 which is connected by a Vsbelt 184 with a pulley 185 keyed onto the spindle 176.

A work receiving collet or chuck is right hand Anon-rotatable housing 188 is supported by a cyhndncal member under pressure to and exhaust fromthe cylinder 193. When fluid is passed under pressure through a pipe 196,

it passes through a passage 197 into a cylinder chamber 198 to move the piston 192 toward the left so as to actuate the collet to clamp a valve to be ground therein. During this movement, fluid within a cylinder chamgroove 201 and out through a pipe 202. A drain pipe 203 is provided for draining fluid fromthe chamber 204.

valve 205 is provided for con- 209, through the pipe 196, through the passage 197 into the cylinder chamber 198 to clamp the work receiving 202, into a valve chamber 210, through a valve passage 211, through v of the valve 205 is provided with an arm 215 which is arranged so that when the control lever is shifted in a counter-clockwise direction into the full line position in Fig. 9, the arm 215 will The operation of the valve grinding machine will be readily apparent from the foregoing disclosure. it IS desired to start a grinding is then shifted from the broken line position 207a (Fig. 9) in a counterclockwise direction into the full line position 207 to clamp the valve 10 within the collet 190. The arm 215 on the control lever swings to close the normally open limit switch LS2. A cycle start switch 220 is then closed to the left hand end of p a passage 200 into an annular pressure pipe 113 passes into a valve chamber energize an electric timer 221 which is arranged to control the grinding cycle; The timer 221 may be any of the well known commercial varieties such as for example the Microfiex eleetrictimer manufactured by theSignal Electric Corp. of- Moline, Illinois. e energizing of the timer 221 serves to en'- ergize the solenoid S2 to shift the valve 160 toward the left so that fluid under pressure is simultaneously passed to the cylinders 60 and 135 to start an axial movement of the grinding wheel 14 toward the right and the grinding wheel 17 toward the left simultaneously to grindthe frusto-conical valve face 11 and the cylindrical face 12 in a manner above described, The movement of the grinding wheel 14 toward the right continues until the stud 140 engages the stop screw 145 which serves to positively limit the infeedthereon. Similarly the feeding movement of the grinding wheel 17 toward the left continues until the stud 63-engages the stop screw 80 positively to limit the feeding movement of the grinding wheel 17.

At the same time the stud- 63 engages thest'op screw 80, the stop screw 84 actuates and closes the limit switch LS1 which energizes the solenoid S1 to shift the valve 97 toward the right so as" to pass fluid under pressure to the cylinder 86 to start a swivelling movement of the wheel slide base 85- in a counter-clockwise direction so-that the faces 20 and 21 on the grinding wheel 17 will grind the bevel face 13 of the valve to the desired and predetermined extent. The swivelling' movement of the wheel slide base 85 continues until the right hand end of the piston rod 88' engages a stop screw 95 positively to limit the swivelling of the grinding wheel 17.

When the timer times out, the solenoids S1 and S2 are deenergized so that the valve 161} returns to the position illustrated in Fig. 9 to return the grinding wheels 14 and 17 to their initial positions as illustrated in- Fig. 8. At the same time deenergizing the solenoid S1- shifts the valve 97 into the position illustrated in Fig. 9 to swivel the wheel slide base 85 in a clockwise direction into its initial position. The ground valve may then be released from the collet 190 by shifting the control lever 207 in a clockwise direction into position 207a. The ground valve may then be removed and a new valve tobe ground insertcd in the collet chuck 190.

A stop switch 222 is provided to-facilitate' stoppingthe grindingcycle at any time during the grinding operation if desired. Actuation ofthe stop switch 222 will serve to dcenergize the timer 2211 thereby deeuergi'zing the sole noids Sland S2 to immediately return the grinding wheels to their initial positions as illustrated in Fig. 8.

It will thus be seen that there has been provided by this invention apparatus in which the various objects hereinabove set forth together with many thoroughly practical advantages are successfully achieved. As many possible embodiments may be made of the'above invention and asmany changes might be made in the embodiment above set forth, it is to be understood that all matter hereinbefore set forth, or shown in the accompanying drawings is to be interpreted as illustrative, and not in a limiting-sense.

I claim:

1. In a valve grinding machine having a base, a rotatable work supporting spindle for supporting a valve to be ground, a transversely rn-ovablewheel headon-said base, a rotatable grinding wheel spindle thereon, spaced bearings on said head to support said spindle, said spindle being arranged for an axial movement within-said bearings, a grinding wheel on saidspindle, the axis of said spindle being arranged parallel to an element of the finish ground work piece, an operative face on said grinding wheel which is shaped so that a portion of the operative element of said wheel face is at an-acute angle to and the remainder of said wheel element is' aligned with anelement of the-surface to'be ground,-means op'er'- atively connected to impart an axial feeding-movement to the wheel spindle so that the first portion of said wheel face gradually grinds the the desired extent after which the second portion ofsaid face finish grinds the work piece, and meansto stop the axial feeding movement of the wheel spindle when the work peice has been ground to a predetermined size 2. in a valve grinding machine as claimed in claim 1, in combination with the parts and features therein specified of means to adjust said wheel head transversely to facilitate compensation for wheel wear and wherein said step means comprises an adjustable stop.

3. in a valve grinding machine having'a base, a rotatable work supporting spindle for supporting a valve to be ground,. atransver'sely movable wheel head on said base, a rotatable grinding wheel spindle, spaced hearings on said head to support said spindle, said spindle being arranged for an axial movement within said bearings, a grinding wheel on saidspindle, the axis of said spindle being arranged parallel to an; element of the finish ground work piece, an operative face on said grindingwheel which is shaped so that a portion of the operative element of said wheel face is at remainder of said wheel element is aligned with an element of the surface to be ground, means'inc-luding a piston and cylinder operatively connected to impart an axial feeding movement tosaid wheel spindle so that the first portion of said wheel face grinds the Work piece and the second portion of said face sizes the work piece, and means to stop the axial feeding movement of the wheel spindle when the workpiece has been ground to the desired extent. I p

4. in a grinding machine having a base, a transversely movablewheel head thereon, swivel support for said head for swivelling said head ina horizontal plane relative to the base, a rotatable wheel spindle on said head, spaced hearings on said-head'to support said spindle, said spindle being arranged for an axial movement within said bearings, a grinding wheel on said spindle having a frustoconical and an adjacent cylindricalr'ace to facilitate grinding a surface on the work piece when the wheel spindle is moved in an axialdirection, means to feed said spindle axially to grind said surface to the desired and predetermined extent, a second portion of the operative face of the grinding wheel having a pair of adjacent frustoconical portions, and means to swivel said head in a horizontal plane after one portion of the work piece has been ground so that the adjacent frusto-conical faces of the wheel swings into engagement with a second portion of the work piece to grind the same to the desired and predetermined extent. Y

5. In a grinding machine as claimed inclaim 4 in combination with the parts and features therein specified of a piston and cylinder mechanism operatively connected to move said spindle; axially within its bearings, and an adjustable stop to limit said axial feeding movement when the work piece has been ground to the desired and predetermined extent.

6. In a grinding machine as claimed in claim 4, in combination with the parts and features therein specified of a piston and cylinder mechanism operatively connected to cause an axial feeding movement of the grinding wheel spindle to grind a portion of the work piece to the desired and predetermined extent, an adjustable stop to limit said axial feeding movement, means including a piston and cylinder mechanism operatively connected to swivel said wheel head, a solenoid actuated control valve therefor, and a limit switch actuated in timed relation with the axial feeding. movement of the grinding wheel to initiate a swivelling movement of the Wheel head after the first surface has been ground to the desired and predetermined extent to grind a second surface on the work piece.

7. In a valve grinding machine having a base, a 1'0- tatable work support spindle for supporting a valve to be ground,- a pair of angnlarly disposed transversely movable wheel head-s onsaid-b'asearranged on opposite sides of the work spindle, a rotatable grinding wheel spindle work piece to approximately an acute angle to and the on each of said heads, spaced spindle bearings on each head to support said spindles, said spindles being arranged for an axial movement Within said bearings, a grinding wheel on each of said spindles, the axis of each of said spindles being arranged parallel to spaced elegronnd work piece, an operative face on each of said grinding Wheels which is shaped so that a portion of the operative element of each of said faces is at an acute angle to and the remainder of the said element is aligned with an element of the surface to be ground simultaneously to grind adjacent portions on a work piece, and means on each of said wheel heads to impart an axial feeding movement to said spindles so that the first portion of each of said Wheel faces rough grinds a surface on the work piece and the second portion on each of said faces finish grinds the work piece to the desired and predetermined extent.

8. In a valve grinding machine having a base, a rotatable work supporting spindle for supporting a valve to be ground, a pair of angularly disposed transversely movable Wheel heads on said base arranged on opposite sides of the Work spindle, a rotatable grinding Wheel spindle on each of said heads, spaced spindle bearings on each head to support said spindles, said spindles being arranged for an axial movement within said bearings, a grinding wheel on each of said spindles, the axis of each of said spindles being arranged parallel to spaced elements of the finish ground work piece, an operative face on each of said grinding wheels which is shaped so that a portion of the operative element of each of said faces is at an acute angle to and the remainder of said element is aligned with an element of the surface to be ground simultaneously to grind adjacent portions on a work piece, means including a piston and cylinder on each of said wheel heads to impart an axial feeding movement to said spindles so that the first portion of each of said wheel faces grinds a surface on the work piece and the second portion on each of said faces sizes the work piece to the desired extent, and means including a solenoid actuated control valve simultaneously to control the admission to and exhaust of iluicl from each of said cylinders so as'to impart asimultaneous axial feeding movement to each of said spindles to facilitate simultaneously grinding adj acent portions on a work piece.

9. In a grinding machine as claimed in claim 8, in combination with the parts and features therein specified of means including an independent piston and cylinder to swivel one of said heads in a horizotnal plane, a pair of adjacent frusto-conical faces on the grinding wheel on said latter head, a control valve therefor, and means actuated by and in timed relation with the axial movement of said spindle on the head that swivels to initiate a swivelling movement of said head to grind an adjacent third face on the work piece being ground.

10. In a grinding machine as claimed in claim 8, in combination with the parts and features therein specified of an electric time delay relay to control said solenoidactuated valve so as to control the duration of the grinding operation, means including an independent piston and cylinder to swivel one of said plane, a pair of adjacent frusto-conical faces on the grinding wheel on said latter head, a solenoid-actuated control valve to control the admission to and exhaust of fluid from said latter cylinder, and means including a limit switch actuated by and in timed relation with the axial movement of said spindle to initiate a swivelling movement of said head to grind an adjacent third face on the work piece being ground.

References Cited in the file of this patent UNITED STATES PATENTS heads in a horizontal

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