US1998603A - Grinding machine - Google Patents

Description

April 23, 1935. w. D. ARCHEA GRINDING MACHINE Filed Feb. 3, 1933 4 Shgets-Shget (Halter D. Avchea m Maw April 23,1935. w. D. ARCHEA 1,998,603

- GQINDING MACHINE Filed Feb. 3, 1953 4 Sheets-Sheet 2 F v wf Siwi l z/hw [Ualter D. Archer:

Patented Apr. 23, 1935 UNITED STATES PATENT OFFICE The Heald .Machlne Company,

Worcester,

Mass, a corporation of Massachusetts Application February 3, 1933, Serial No. 655,069

11 Claims.

The present invention relates to grinding machines and particularly to a surface grinder for use especially in the grinding of the faces of discshaped articles such as clutch discs and the like.

In prior devices of this character. the grinding wheel is moved into and out of operative position and the relative feeding movement of the workpiece is procured either manually or in certain cases at a predetermined constant rate by me' chanically controlled mechanism. One of the principal objects of the present invention is to provide a feeding movement which advances the workpiece toward the grinding wheel at a constantly diminishing rate. In this manner. the grinding operation begins with a relatively coarse feed and is gradually reduced to a very fine or slow feed which results in a smooth polished surface. I

A further feature of the invention resides in the provision of a machine of the surface grinder type, the cycle of which is automatically controlled. the machine being brought to rest at the completion of a grinding operation. In this machine, the grinding operation is discontinued in response to rotation of the workpiece or the workholding member in which the workpiece is mounted.

Other objects and advantages of the invention will more fully appear from the following detailed description taken in connection with the accompanying drawings in which:-

Fig. i is a front elevation of a machine embodyingthe invention.

Fig. 2 is a plan view of the machine of 'Fig. 1.

Fig. 3 is a vertical section along the line 3-3 of Fig. 2, showing the construction of the workholder. r

Fig. 4 is a vertical section along the line 4-4 of Fig. 3 showing the driving mechanism for the workholder.

Fig. 5 is a vertical section along the line 3-4 of Fig. 4.

Fig. 6 is an enlarged fragmentary view of-the clutch and brake unit shown in Fig. 4.

v Fig. 7 is a vertical section substantially along the line 'I-'i of Fig. 2.

Fig. 8 is an enlarged detail of the structure of Fig. 7 as viewed along the line 8-8 of this figure.

Fig. 9 is a sectional view along the line' 9-9 of Fig. 'I.

Fig. 10 is a vertical section substantially along the line lliill of Fig. 7 showing the fluid pressure mechanism for actuating the workhead.

Fig. 11 is a vertical section along the line I l-i I of Fig. 1.

Fig. 12 is a vertical section along the line l2-l2 of Fig. 11 showing the control valve for the workhead. i

Fig. 13 is a section along the line l3l3 of Fi 12.

Fig. 14 is a section along the line l4--l4 of Fig. 13.

Fig. 15 is a detailed section along the line l5-I5 of Fi 12.

Fig. 16 is a fluid pressure diagram. 10

Like reference characters refer to like parts in the different figures.

Referring to Figs. 1 and 2, the machine comprises a base i on which is mounted a housing 2 for agrinding wheel 3, the spindle of which is 15 Journaled in horizontal bearings I also mounted on the base. The base also provides ways 5, see Figs. 4 and 11. on which a table or carriage 6 is horizontally movable toward or away from the grinding wheel and perpendicularly to the axis 20 thereof. The carriage 8 has. as an integral part thereof, a workhe'ad or housing I which provides a support for a rotary workholder 8 in which a workpiece a. is mounted. Said workpiece, which is shown as a disc having an annular fiat surface to be ground, is positioned with thesurface to be ground in opposed relation to the periphery of the grinding wheel and the latter, as will be apparent. is at least as wide as the width of the annular surface of the workpiece between the inner and outer edges thereof in order that the wheel may grind over the entire width of the surface 01 the workpiece without a reciprocatory traverse of said wheel.

Referring now to Fig. 3, the workholder 8 is 85 carried on the end of a hollow spindle 8 which is ioumaled in bearings 10 provided by the housing I. A worm gear ii is secured against rotation and against axial movement on said spindle and is in engagement with a worm I! carried by 40 a shaft l3 journaled as shown in Fig. 4 in the housing 1. Said shaft I! is connected through a clutch and brake mechanism i4. shown in detail in Fig. 6 and hereinafter more fully described. to a pulley i 5 in a housing It secured to the hcusing Said pulley i5 is connected by a suitable belt H to a pulley IE on the shaft of a driving motor It, said belt l1 and pulley l8 being also mounted in the housing It.

A draw rod 20 is longitudinally slidable in the hollow spindle 9 and is connected in any suitable manner to the jaws ii of the work-supporting member or workholder 8. the latter being of any desired type in which a movement of the draw rod to the right, Fig. 3, operates to close the jaws for clamping a workpiece therein, and movement of said draw rod to the left operates to open the jaws for releasing the workpiece. For actuation of the draw rod 20, the spindle 9 carries a flange 22 on the right hand end thereof, and said flange has secured thereto a cylinder 23 in which a piston 24 is slidable, said piston being connected by a pistonrod 25 to the end of the draw rod 20. Fluid under pressure is admitted selectively to opposite sides of the piston for opening or closing of the jaws of the workholder.

Referring now to Fig. 16, fluid under pressure is supplied by a pump 26 which draws fluid from a tank 21 in'the base of the machine. From the pump, fluid under pressure is conducted by a pipe 28 to an inlet port 30 in a valve casing 3|, the latter being positioned on the front of the machine, as shown in Fig. 1. Said casing is provided with an exhaust port 32 connected by a conduit 33 to the tank and is also provided with outlet ports 34 and 35 connected by pipes on either side of the piston. The jaws of the workholder may thus be opened or closed as desired by movement of the lever 46 which, as willv be apparent, is accessible on the front of the machine.

As above stated, the hollow work-supporting spindle 9 is brought to rest or set in rotation by actuation of the clutch and brake mechanism |4 without stopping the driving motor l9. Referring now to Fig. 6, in which this mechanism is shown in detail, the shaft l3 by which the spindle 9 is rotated is recessed at one end thereof to provide a journal for the left hand end of the shaft 4| on which the pulley I5 is mounted, said shaft 4| being journaled in the housing 1 in axial alinement with the shaft l3. The shaft 3 has secured thereto a member 42 adjacent the right hand end thereof and within the opening 43 provided in the housing I for the clutch and brake mechanism. Said member 42 has a plurality of projecting pins 44 which extend parallel to the axis of the shaft l3 and provide a support for an annular friction or clutch disc 45, the latter being axially slidable on said pins.

The end of the shaft 4| adjacent the end of the shaft l3 has a member 46 secured against rotation thereon and the member 46 provides an annular surface 41 on which a pair of annular friction or clutch discs 48 and 49 are longitudinally slidable and supported against rotation thereon. Said member 46 also provides a-plurality of bell crank levers 50 mounted in slots provided by said member and pivoted on pins 6| therein. One end of said bell crank levers engages the outer of the two friction discs 46 and 49 for urging said discs toward each other and into engagement with the friction disc 45 which is positioned between them to prevent relative rotation between said disc 45 and the other discs to procure in response to rotation of the member 46 a corresponding rotation of the shaft l3.

The member .48 providm a shoulder 5| against.

which the friction discs are urged by the bell crank levers, said shoulder preventing movement of said discs to the right.

An actuating member 52 for the bell crank levers 50 which is slidably mounted on the shaft 4| and secured against rotation thereon has an annular cam-shaped surface 53 for engagement with the free ends of the bell crank levers 56 for supporting said levers in the position shown with the friction discs in positive driving engagement. Movement of the actuating member 52 to the right from the position shown releases the bell crank levers to permit separation of the several friction discs, thereby breaking the drive connection between the shaft 4| and the shaft |3 so that the latter may be brought to rest. Movement of the member 52 to the left reengages the clutch disc to procure rotation of the shaft l3 and accordingly rotation of the workholder 8.

The actuating member 52 is provided with an integral annular flange 54 on which a grooved ring 55 is rotatably mounted, said ring being split to permit mounting of the latter upon said flange. Said ring 55 is provided with projecting pins 56. in diametrically opposed relation and said pins are received in notches 51 in the ends of a bifurcated member 58 which is mounted on the lower end of a rod 59. The latter is provided with an enlarged spherical portion 60 which is journaled in a cover plate 6| suitably secured over an opening 62 in the housing I, said spherical portion providing for rocking movement of said shaft.

Referring now to Fig. 4, the upwardly projecting end of the rod 59 beyond the spherical portion 60 has secured thereto a U-shaped member 63, the ends of which are provided with alined openings for the reception of a pin 64 carried by the end of a rod 65. The latter forms an extension of a piston rod 66 projecting from a piston 61 which is movable in a cylinder 68 mounted on the housing I and which is actuated in response to fluid under pressure admitted selectively to the cylinder on either side of the piston. Movement of the piston 61 to the left procures a corresponding movement of the actuating member 52, Fig. 6, to the right to separate the clutch discs, and movement of said piston to the right procures, through movement of the. member 52 to the left, reengagement of said clutch discs, thereby procuring rotation of the workholder 8 in response to-rotation of the shaft 4|.

When the connection between the shafts l3 and 4| is broken, the workholding member 8 is brought to rest by a brake mechanism, the construction of which is best shown in Figs. 5 and 6. Referring to these figures, the member 42 which, as above stated, is secured to the end of the shaft I3, is provided with a, cylindrical surface 10 which is encircled by a brake band II. The opposite ends of said brake band are provided with suitable lugs 12 and 13 through which a rod 14 projects, said lugs being urged apart by a spring 15 which encircles said rod. One end of said rod 14 is slidable in a sleeve 16 secured in-the housing I and the opposite end of said rod is slidable in a cap 11 forming one end of a cylinder I8 in which a piston 80 secured to the end of said rod 14 ismovable, said cylinder being suitably secured to the housing I. The rod I4 carries a collar 6| adjustable thereon and in a position to engage with the lug 13 during movement of said rod to the left, Fig. 5. The opposite lug 12 engages the end of the sleeve 15 so that a movement of the rod I4 to the left tightens the brake band around the surface 18 to bring the shaft I8 and accordingly the workholder 8 to rest. Movement of said rod 14 to the right from the braking position releasesthe lug 18 and the spring 18 procures separation of the lugs 12 and 13 to release the brake band. Shifting movement of the rod 14 is procured by admission of fluid under pressure selectively to the cylinder 18 on opposite sides of the piston 88, as will be pointed out hereinafter, for shifting of said piston to one end or the other of the cylinder, thereby procuring 9. corresponding movement of the rod 14 secured thereto.

With a workpiece a mounted in the workholder 8 and rotated from the driving motor I8, a movement of the workhead to the left, Fig. 1, is procured by fluid under pressure for a movement of the workpiece into grinding position and for a feeding movement of said workpiece against the grinding wheel, said movements being procured by movement of the table 8 on which the workhead is mounted. Referring particularly to Fig. 'I, the housing 1, of which the table Ii is a part, has secured thereto a housing 82 in which an internally threaded sleeve 88 is journaled, the latter being supported against axial movement in said housing. Said sleeve 88 receives a threaded rod 84, the right hand end of which is provided with a' U-shaped member 85 secured thereto by a set screw 88. The ends of said member 85 are connected by, and provide a support for, a pin 81 on which one end of a link 88 is pivotally mounted, The opposite end of said link 88 is mounted on a pin 88 carried by an enlarged portion SI of a shaft 82 (see Fig. 10) journaled in a bracket 83 which is secured by bolts 84 to the base-of the machine. The pin 88 is eccentric' to the axis of the shaft 82 so that turning movement of said shaft procures a longitudinal movement of the member 88 and corresponding feeding movement of the housing 1 to the left.

Rotation of the shaft 82 is procured in response to fluid under pressure. Referring to Figs. 7 and 18, the shaft 82 carries, at the end remote from the enlarged portion 8i, a gear 85 secured against removal and against rotation on said shaft by a nut 88. Said gear which is positioned withina recess 81 in the bracket 88 engages a rack 88 verticallymovable in a bore I88 provided in said bracket. Said rack 88 is secured to and forms an extension of a piston rod IN and the lower end of the latter is secured to a piston I82 in a cylinder I88 secured to the bracket 83. The piston rod I8I just above the piston I82 is provided with an enlarged cylindrical portion I84 and a projecting portion I85 on the lower end of said rod extends a short distance below the piston; 'said portions I84 and I88 control the rate of movement of the piston within the cylinder as will hereinafter appear.

Fluid under pressure is admitted to either end of the cylinder above or below the piston to procure movement of the same for actuating the :workhead. As'the piston mcfves upwardly in response to fluid under pressure entering below the piston, the rack is moved upwardly therewith,

procuring a turning movement of the shaft 82 (as seen in .Fig. 7) and corresponding longitudinal movement of the workhead 1 toward the grinding wheel to ladvance the workpiece into grinding position and to feed the workpiece against the grinding wheel when in grinding position. The workpiece is withdrawn from the grinding wheel during the downward movement of the piston to provide for removal of thecompleted workpiece 'bore II8 connecting said horizontal channel to and positioning of an unground workpiece in the workholding member 8. As will be pointed out hereinafter, the crank motion for feeding the workpiece against the grinding wheel results in a rapid feeding movement at the beginning of the grinding operation which is gradually reduced during that operation until, in the forward position of the carriage which supports the workpiece, there is no forward feed and a very smooth finish is accordingly produced on the workpiece.

The movements of the piston I82 are under the control of valves best shown in Fig. 10. Referring to this figure, the cylinder head I88 at the upper end of the cylinder I88 is providedwith a horizontal channel I81 which extends from an inlet port I88 and intersects a vertical cylindrical bore I88 surrounding the piston rod. Said bore is of,"

valve III provided in said horizontal channel. 5

An additional vertical bore H2 is provided in the cylinder head I88 and intersects the horizontal channel I81. The bore H2 is provided with a suitable check valve II8, the latter being, for example, in the form of a ball urged against the valve seat by a spring, said valve being of wellknown construction. The check valve H3 is positioned to permit free passage of fluid into the cylinder during downward movement of the piston and to prevent exhaust of fluid through said bore II2 during upward movement of said pis ton. The lower cylinder head II4 for the cylinder I88 is similarly provided with a port II! from which extends a horizontal channel H8 intersected by a vertical bore II1 which is of the proper size and in a position to receive the projecting end I88 of the piston red as the piston approaches the lower limit of movement. Said horizontal channel I I8 is also intersected by a vertical the interior of the cylinder, and the fluid supply through said vertical bore is limited by a needle valve I28 similar to the valve III and of any suitable construction. An additional vertical bore I2I which intersects the horizontal channel is provided with a check valve' I22 similar 'to the check valve I I3. The check valve I22 is arranged to prevent exhaust of fluid'through the bore I2I from within the cylinder, although admitting fluid freely into the cylinder during upward'movement of the piston.

As fluid enters the cylinder I88 beneath the piston I82 for advancing the workpiece toward the grinding wheel, the piston moves upwardly to the position shown in Fig. 10 at a rapid rate. fluid being admitted freely to said cylinder past the check valve I22. As soon as the piston is advanced far enough to withdraw the projecting end I85 of the piston rod from the vertical bore II1, the fluid under pressure may enter through said vertical bore for procuring a continued up-- ward movement of the piston. At the same time, fluid from above the piston exhauststhrough the vertical bore I88 surrounding the piston rod so that the exhaust of fluid is unthrottled.

The rapid movement of the piston upwardly procures a rapid advance of the workpiece from inoperative position into operative or grinding position andthis movement would, if not suitably checked, cause the workpiece to engage the grind- .operation on the workpiece.

ing wheel too rapidly. To avoid this condition, the rate of movement of the workpiece toward the grinding wheel is materially reduced just as the workpiece comes into contact with said wheel. At this point in the advancing movement of the workpiece, the piston is approaching the upper end of its movement. Just before the workpiece engages the grinding wheel, the enlarged portion I04 enters and closes the'vertical bore I08 so that further exhaust of fluid from above the piston during the remainder of the upward movement of said piston occurs at a very slow rate past the needle valve, escape of fluid through the bore II2 being prevented by the check valve. This material reduction in the rate of exhaust of fluid from the cylinder causes the piston to travel at a very reduced rate of speed during the remainder of its upward movement for a slow feeding movement of the workpiece against the grinding wheel. The crank motion by which the movement of the workhead is procured in response to the rotation of the shaft 82 results in a constantly diminishing rate of feed in response to the movement of the piston at a uniform rate. The feeding movement of the workhead is discontinued when the piston reaches the upper end of its movement at which time the eccentric pin 90 is in horizontal alinement with the shaft 92 and theworkhead remains in the forward position with the workpiece in engagement with the grinding wheel for a short period in order to procure a finish grinding The workhead is then retracted into inoperative position at a rapid rate, as will hereinafter appear.-

Upon reversal of the flow of fluid to the cylinder I03 the piston I02 moves downwardly to withdraw the grinding wheel from the work piece.

The movement of said piston occurs at a relatively rapid rate, the fluid from beneath the piston exhausting through the bore I "until the piston approaches the end of its downward movement. At this time, the projecting end I05 of the piston rod enters and closes the vertical bore III to prevent further exhaust of fluid through said bore, the fluid thereafter exhausting slowly past the needle valve I 20 so that the remaining downward movement of the piston is procured at a relatively slow rate. The workhead is thus brought to rest in inoperative position when the piston reaches the lower end of its movement without any excessive jarring of the parts which would occur if the rate of movement of the piston were not decreased.

The workholding member 8 is set in rotation at the beginning of the forward movement of the workpiece toward the grinding wheel. Referring now to Fig. 16, the admission and exhaust of fluid under pressure to and from the clutch cylinder, the brake cylinder, and the work-feeding cylinder is controlled by a single valve I23 in a casing I24. During the movement of the -workpiece toward the grinding wheel the valve I23 is held in the left hand position shown by a latch I25 against the tension of a spring I26. An inlet port I21 in the valve casing I24 is connected by a conduit I28 to the pressure side of the pump, and exhaust ports I30 and I3I in said casing are connected by conduits I32 and I33 to the tank 21. An outlet port I34 in said casing is connected by a conduit I35 to the left hand end of the clutch cylinder 68 and byconduits I36 and I3I to the left hand end of the brake cylinder I8 and to the lower end of the work-advancing cylinder I03 respectively. Another outlet port I38 is connected by leads I40, I and I42 to the right hand end of the clutch cylinders, the right hand endof the brake cylinder and the upper end of the wdrkfeeding cylinder respectively.

With the. valve I23 in the position shown, fluid under pressure is admitted to the left hand end of the brake cylinder I8 for shifting the piston 80 therein to the right, thereby releasing the brake to permit rotation of the work-supporting member. At the same time, fluid under pressure is admitted to the left hand end of the clutch cylinder 68 to procure engagement of the clutch discs and thereby to cause rotation of the worksupporting member. Fluid under pressure is also admitted at this time to the under side of the work-advancing piston I02 for advancing the workpiece from inoperative position into operative relation to the grinding wheel and for a feeding movement of said workpiece against the wheel.

The valve I23 is supported in the left hand position shown for a predetermined period and is then released from the latch for movement to its right hand position under the influence of the spring I26. In this position of the valve, fluid under pressure is directed to the right hand ends of the clutch and brake cylinders and to the upper end of the work-advancing cylinder for retracting the workpiece from the grinding wheel, for disengaging the clutch discs, and for bringing the workholding member to rest. The valve I23 in its right hand position also connects the opposite ends of said cylinders to the exhaust port of the casing I24 to permit discharge of fluid from within said cylinders.

The grinding operation is controlled by the rotation of the workholding member, and after a predetermined rotation thereof, the above noted valve I23 is automatically shifted to the right hand end position to bring the grinding operation to a close. Referring now to Fig. 3, the spindle 9 for the work-supporting member 8 has a sleeve I43 secured against rotation thereon and provided with gear teeth I44 engaging with similarly formed teeth on a gear I45 keyed to a shaft I46 journaled, as shown in Fig. 11, in bearings I4'I secured in the workhead. Said shaft I46 has an enlarged end I48 remote from the gear I45 and this end is provided with a slot I50 for the reception of a tongue I5I formed on the end of a shaft I52 joumaled in a housing. I53 which is secured to the workhead. The shaft I 52 carries a worm I54, Fig. 12, which engages with a worm gear I55 carried by a shaft I56 also journaled in the housing I53. I An annular member I5'I surrounds said shaft I56 and is secured to the worm gear I55 by bolts I58 for rotation therewith. One end of said annular member I51 provides a star wheel I60 (Fig. 13) for engagement with one end of a plunger I6I longitudinally slidable in a bearing I62 provided by a cap I63 secured to the housing I53. A threaded rod I64 engages a threaded bore in the end of said plunger I6I and carries on the outer end thereof a projecting arm I65 which is secured against rotation on said rod. The plunger I6I is held against rotation in the bearing I62 by a suitable key and thus supports the arm I65 in a position for engagement with the projecting arm I66 of a member I61 secured against rotation on a shaft I68 by a set screw I10, said shaft being journaled in the housing I 53.

As shown in Fig. 14, the end of the shaft I68 remote from the member'I6I has an enlarged valve I28 is held in the left hand position shown. Thus, as the star wheel I88 is rotated, in response to the rotation of the work-supporting member, to carry a point of said wheel beneath the end of a plunger i8 I, said star wheel shifts the plunger to the left to rock the shaft I88 and thereby withdraw the iach I25 from the collar I18 on the valve I23 with which the latch engages. As the latch is withdrawn, the valve I28 is shifted by the spring I26 into its right hand position, thereby withdrawing the workhead from grinding position and stopping rotation of the workholding member. 'The control valve I28 has a projecting stem I14, Fig. 12, provided with spaced collars I18 for the reception of a pin I18 carried on the end of an arm I11. The latter is secured against rotation on the inner end of a shaft I18 journaled in the workhead (see Fig. 11), and the forward endof said shaft projects beyond the forward surface of the workhead and carries an upwardly extending lever I88 by which said valve'may be manually shifted to the left for starting a grinding operation.

During the grinding operation, the pressure of the grinding wheel against the workpiece exerts an axial thrust on the workholding member and, as shown in Fig. 3, the worm gear II, which is secured to'the spindle 8, is provided with a flat annular surface I8I for engagement with a wear ring I82 secured, as by pins I88, to a portion of the workhead to prevent axial shifting of the spindle within said workhead.

To compensate for the reduction of the diameter of the grinding wheel resulting from wear thereon, as well as from dressing operations by which the surface is maintained in proper cutting position, the position of the carriage relative to the advancing mechanism is shifted by a mechanism best shown in Figs. 7 and 9. Referring to these figures, the sleeve 88 which, as above stated, is journaled in the housing 82, is provided with an integrally formed worm gear I84 which isengaged by a worm I88 mounted on a shaft 188, the latter being journaled in the housing 82. Said shaft is held against longitudinal movement in the housing 82 by collars I81 and I88, Fig. 9, secured in spaced relation to said shaft and engaging the housing 82. One end of said shaft I88 projects beyond the housing and has a hand wheel K90 secured thereto, the latter having a handle I9I by which to procure rotation of the worm I88 and corresponding rotation of the sleeve 88. Rotation of said sleeve, as will be apparen procures advance or retraction of the threaded rod therein and accordingly shifts the position of the carriage 6 relative to the carriage advancing mechanism. A set screw I92 which extends through a cap I98 carried by the housing engages the shaft I88 to prevent unintended rotation thereof.

Assuming the parts are in the position shown in the flgures, the workhead is in its advanced position at the completion of the forward feeding movement between the grinding wheel and the workpiece, the workholding member is being rotated by the motor l8, and the grinding wheel is in contact with the workpiece therein for completing the grinding operation. The rotation of the work-supporting spindle 8 procures a slow turning movement of the star wheel which, after a predetermined period, shifts the plunger I8I, thereby to release the valve. I28 from the latch I25, said valve then being automatically shifted to the right to supply fluid under pressure to the upper end of the work-feeding cylinder to retract the workpiece from operative engagement with the grinding wheel. Said valve also, upon movement to the right, directs fluid under pressure to the right hand ends of the clutch and brake cylinders so that, as the workpiece is withdrawn from the grinding wheel, the driving motor is disconnected from the work-supporting spindle 9, and the latter is brought to rest by the brake mechanism. The machine come; to rest with the workhead at the right hand end of its movement in which position the workpiece is spaced from the grinding wheel.

With the workhead in this right hand position, the lever 40 is manually oscillated to admit fluid under pressure to the right hand end of the chuck actuating cylinder for opening the jaws of the chuck to permit removal of the finished workpiece and the substitution of an unground workpiece therein. The lever 40 is then again actuated for directing fluid under pressure to the left hand end of the chuck controlling cylinder, thereby clamping the unground workpiece in said workholder. A grinding operation is then procured on the unground workpiece by rocking movement of the lever I88 which shifts the control valve I28 tothe left into the position shown, thereby procuring rotation of the work-supporting member and advance of the workpiece toward the grinding wheel. The work-supporting member then advances rapidly toward the wheel until the workpiece is substantially in engagement with said wheel, when the rate of movesurface on said workpiece. After an interval, the

star wheel which is rotated from the work-sup- ,porting spindle again procures shifting move-.

ment of the valve I23 to the right and the abovedescribed operation is repeated.

I claim,

1. In a grinding machine, a grinding wheel and a workholding member, means for rotating said member, clutch and brake mechanisms between said rotating means and said workholding member, fluid pressure means for actuating said clutch and brake mechanisms, and means responsive to the rotation of said workholding member for controlling the admission and exhaust of fluid under pressure to said fluid pressure means.

2. In a grinding machine, a grinding membe a work-supporting member, means for rotating said work-supporting member, a carriage on which one of said membersf'is mounted, means to actuate said carriage for advancing said members into operative position and for a relative feeding movement between said members, said actuating means also procuring a subsequent retraction of said members, and means responsive to the rotation of said workholding member to. procure the retraction of said carriage for separating the grinding member from a workpiece carried by the work-supporting member.

3. In a grinding machine, a grinding member,

a workholding member, means for rotating said workholding member, a carriage on which one of said members is mounted, fluid pressure means for moving said carriage, and means responsive to the rotation of the workholding member to control the admission and exhaust of fluid under pressure to said fluid pressure means.

4. In a grinding machine, a grinding member and a workholding member, a carriage on which one of said members is mounted, said carriage having an inoperative position and an operative position, fluid pressure actuated means to procure movement of said carriage into operative position, means responsive to movement of said fluid pressure actuated means to reduce the rate of movement of said carriage as the latter approaches operative position, and means for procuring a subsequent feeding movement of the carriage at a continuously changing rate in response to the operation of said fluid pressure ac-v tuated means.

5. In a grinding machine, a grinding member and a workholding member, a carriage on which one of said members is mounted, said carriage having an inoperative position and-an operative position, fluid pressure actuated means to procure movementof said carriage into operative position, and means responsive to movement of said fluid pressure actuated means to reduce the rate of movement of said carriage as the latter approaches operative position, said fluid pressure actuated means thereafter procuring a slow feeding movement of the carriage at a continuously decreasing rate.

6. In a grinding machine, a grinding member and a workholding member, a carriage on which one of said members is mounted, fluid pressure actuated means including a cylinder and'piston, and means providing a connection between said fluid pressure means and the carriage and responsive to a uniform movement of said fluid pressure actuated means to procure a movement of said carriage at a continuously changing rate.

'7. In a grinding machine, a grinding member and a workholding member, a carriage on which one of said members is mounted, fluid pressure actuated means, means responsive to a uniform movement of said fluid pressure actuated means to procure a movement of said carriage at a continuously changing rate", and means to procure a change in the rate of movementof said fluid pressure actuated means during the operation thereof.

8. In a grinding machine, a grinding member and a workholding member, a carriage on which one of said members is mounted, fluid pressure actuated means, means responsive to a uniform movement of said fluid pressure actuated means to procure a movement of said carriage at a continuously changing rate, and means operable in response to the movement of said fluid pressure means to procure a change in the rate of movement of said fluid pressure actuated means during the operation thereof.

9. In a grinding machine, a grinding member workpiece.

10. In a grinding machine,'a grinding member and a work-supporting member, means for m-' tating a workpiece in said work-supporting member, a carriage on which one of said members is mounted, hydraulically actuated means to procure a movement of said carriage for a relative feeding movement between said grinding member and the workpiece in said work-supporting member, and means responsive to the rotation of the workpiece in the work-supporting member for procuring a retraction of the carriage and a cessation of rotation of the workpiece.

11. In a-grinding machine, a grinding member and a work-supporting member, a carriage on which one of said members is mounted, and hydraulically actuated means for procuring movement of said carriage for arelative feeding movement between said grinding member and a work piece in said work-supporting member, said means including a cylinder and piston, a rack on-one of said parts, a pinion engaging said rack, and means providing a connection between said 'pinion and carriage and responsive to rotation of said pinion for. procuring movement of said carriage at a constantly changing rate when the pinion is rotated at a uniform rate.-

WALTER D. ARCHEA.

Images