US2163246A - Grinding machine - Google Patents

Description

June 20, 1939.

7 G. F. MAGLOTT.

GRINDING MACHINE 5 Sheets-Sheet 1 I I I H] hlllll Filed May 18, 1937 June 20, 1939. G. I? MAGLOTT 2,163,246

GRINDING MACHINE.

Fild May 18, 1937 5 Sheets-Sheet 2 June 20, 1939.

G. F. MAGLOTT GRINDING MACHINE Flled Ma 18, 1957 Fig.

5 Sheets-Sheet 3 Patented 1...... 20, 1939.

UNITED STATES GRINDING-HACKNE- George F. Kaglott, Wrentliam, Masa, ass'ignor to Brown and Sharpe Manufacturing Company, a corporation of Rhode Island Application May 18, 1937, Serial No. 143,314

2-: claim."

wheel, a reciprocating work support, and a cross feed carriage support on which the grinding wheel is carried for movements toward and away from the work.

It is the principal object of the present invention to provide novel and improved hydraulic driving and controlling devices for the work support .and cross feed which are well adapted for the performance of either traverse or plunge cut grindingoperations, and thereby to secure a simplified and more emcient operation of the machine.

More specifically, it is an object of the invention to provide novel and improved hydraulic driving and controlling .devices for producing alternative continuous or intermittent relative cross feeding movements of the grinding wheel and work.

It is a further object-of the invention toprovide an improved hydraulically operated control 25 mechanism for reversing the direction of table travel, and .for controlling the operation of the cross feed motor therefrom to produce a carefully regulated and accurate cross feeding movement at each reversal of' table travel. 1 With these and other objects in view as may hereinafter appear, the several features of the invention consist also in the devices, combinations and arrangement of ,parts hereinafter de-' scribedand claimed, which together with the advantages to be obtained thereby, will be readily understood by one skilled in the art from the following description taken in connection with the accompanying drawings, in which Fig. 1 is a view'in front elevation of a cylindrical grinding machine; Fig. 2 is an enlarged detail view in front elevation partly in section, illustrating particularly the hydraulic unit including the-tableand cross feed fluid motors and the several control valves and connections associated therewith;

45 Fig. 3 is a sectional plan view taken on the line 3-3 of Fig. 2, illustrating particularly "the reversing lever booster piston, the cross feed motor, and the cross feed starting piston; Fig. 4 is a sec-' tional view in left side elevation takenpn the line I 50 4-,-4 ,of Fig. 2, illustrating particuiarlythe-reversing lever and certain of its actuating connectionsrandthe selectorvalve'; Fig. 5 is a detail view in front elevation of the controls illustrated in Fig. 4 Fig. 6 is a'sectionalpla'h view taken on the line $8 of Fig. 4, illustrating particularly the table reversing valve; Fig. 7 is a detail sectional plan view of the selector valve taken on the line l of Fig. 2; Fig. 8 is a detail sectional view taken on the line 8-8 of Fig. '7: Fig. .9 is a sectional view in left sideelevation taken on the line 99 of Fig. 2, illustrating particularly the cross feed fluid motor and the connections therefrom for actuating the cross feed; Fig. 10 is-a detail sectional view taken on the line Ill-J0 of Fig. 9, to illustrate particularly the valve control for producing an intermittent drive of the cross feed member; Fig. 11 is an enlarged detail sectional view taken. on the line llll of Fig. 2, illustrating particularly the table start and stop valve and actuating connections therefor; Fig. 12

is a detail view in front elevation illustrating certainof the connections shown in Fig. 11; Fig. 13

is a sectional view taken on the line l3-l3 of Fig. 11; Fig. 14 is adiagram of the hydraulic driving and control system for the machine; and Figs. 15 and 16 are sectional views of the start and stop valve respectively on lines li-li and l6--l6 of Fig. 14.

The invention is herein disclosed as embodied in a cylindrical grinding machine which may be of ordinary description, comprising a base 2|! having supported thereon a longitudinally reciprocable work table 22 and a transversely movable carriage support 24 for a rotary grinding wheel 26. The machine, is also provided with a tail stock 28 and a headstock 30 which is driven by means of an electric motor '32 supported as an integral part of the headstock unit.

In the preferred construction illustrated, power operation of the work supporting table 22 and of the cross feed mechanism for imparting feeding and retracting movements to the carriage support 24 and grinding wheel 26 is achieved by means of hydraulic actuating and control devices which form specifically thesubject-matter of the present invention.

The hydraulic connections for driving the table, as best shown in Figs. 1 and 2, comprise a cylinder 34 rigidly secured to the base 20, a piston 36 and a piston rod 38 which passes through packings formed in opposite ends of the cylinder 34, and is secured at its opposite ends to brackets 40 and 42,611 the under side of the work supporting table 22. Oil under pressure is supplied for driving the table from a reservoir N in the machinevbase, by means of a pump 46 (see Figs. 1 and 14) passing upwardly through a pipe connection 48 to a selector valve 50, thence through a pipe connection 52, through-a throttle valve I4 and pipe connection 56 to a reversing valve 58, from which fluid under pressure is directed alternatively through pipe connections or 62 to the left hand or right hand end of a table driving cylinder 34 as desired.

The throttle valve 54, as best shown in Figs. 4 and 5 of the drawings, comprises a cylindrical valve member having formed therein a conventional V-shaped opening 55 for throttling the rate of admission of fluid pressure from the inlet pipe 52. The throttle valve 54 is controlled through connections which include a valve stem 51' having mounted on its forward end a gear 50 which meshes with a gear 8| connected to turn with a table speed knob 84 on the control panel 68 of the machine.

The reversing valve 58, as best shown in Figs. 2, 4, 6 and 14, is of the rotary type comprising a cylindrical valve member 88 having formed therein a duct I0 which is adapted to connect the pressure line 56 alternatively, with lines 80 or 62 leading to opposite ends of the cylinder 34. The valve member 68 is also provided with a duct I2 which is arranged simultaneously to connect the other of said lines 80 or 82 to an exhaust pipe connection I4, which forms an extension of the main exhaust line 15 through which liquid is returned to the reservoir 44. A relief valve 11 is provided in the exhaust line I5 to maintain the liquid in the system at all times under a certain minimum pressure.

In accordance with one feature of the present invention, there is provided an improved table start and stop valve which is simple in construction, and is adapted to operate in a novel manner when shifted to stop position, to positively arrest table movement, and thereafter to connect the two ends of the piston with one an other and to pressure, while at the same time a connection is made between pressure and exhaust so that the table may be readily moved by manual operation to any desired position. The valve operates in stopping the table to shut off the supply and exhaust connectionto one end only of the table cylinder 34, acting when liquid is being admitted at feed pressure to stop the table against a vacuum and when fluid is being exhausted from that end of the cylinder to stop the table against a solid column of liquid. The table start and stop valve, as best shown in Figs. 2, and 11 to 16 inclusive, comprises a rotatable valve member 16 having formed therein a T-shaped duct 18 which is arranged for the operative position of the valve illustrated in Fig. 14, to connect pipe 60 and an extension 80 of pipe 80 to the left hand end of the cylinder 34. For the inoperative or stop position of the valve, the T-shaped duct I8 provides a connection between the pipes 80 and 80 and also provides a direct connection through an additional pipe line 82 and pipe line 82 between the two ends of the. cylinder 34. There is also provided in the start and. stop valve member I6, a duct 84 which operates when the valve is moved to stop position, to provide a connection between an extension 86 of pressure line 52 and a pipe connection 88 forming an extension of the exhaust line I5, and thereby to reduce the pressure in the entire-system to a low exhaust pressure as determined by the setting of a. relief valve II in the line I5. As best shown in Figs. 2 and 13 of the drawings, the reversing valve member 58 and the start and stop valve member I6 are mounted in cylindrical bores formed in a single casing or block member 80 which is secured by means of bolts 82 and 84 to the under side of the cylinder 34. The block 80 has secured thereto, an additional block or casing member 88 housing certain others of the operating and control valves of the machine. The position of the start and stop valve is conveniently controlled, as best shown in Figs. 11 and 12, through connections which include a rotatable shaft 98 forming an extension of the valve member I6, and provided at its outer end with a spiral gear I00 which meshes with a gear I02 on. an upwardly extending shaft I04. The shaft I04 is connected by a coupling I05 to turn with a control shaft I06 which carries on its upper end a knob I08 for convenient manipulation by the operator.

The operation of the start and stop valve to control the starting and stopping of the machine will be readily understood in connection with Figs. 14, 15 and 16 of the drawings. Assuming that the valve is in running position, fluid pressure is freely admitted or exhausted as determined by the position of the reversing valve 58 from the right hand end of the table cylinder 34 through pipe connection 62, and is similarly admitted or exhausted from the left hand end ofthe cylinder 34 through pipe connection 60, duct I8 and connection 88. The duct 84 is at this time turned to a position to shut off the connection between the pressure line 86 and exhaust line 88. the operation of the machine, the valve is turned in a counterclockwise direction as viewed from the front of the machine, through a angle. Dur-- ing this movement, the T-shaped duct I8 will pass through the dot-and-dash position shown in Fig. 14, thus for an instant completely shut ting off all connection with the left hand end of the cylinder 34, and causing the table to come to a full stop. The continued movement of the valve to its stop position then causes the left hand end of the cylinder including the pipe connection 80 to be again connected with the line 60 and reversing valve 68, while at the same time a connection is made through line 82 with pipe line 62 and the right hand end of the cylinder 34. For this stop position of the valve, the left hand end of the cylinder 34 is therefore connected to the right hand end of cylinder 34 independently of the position of the reversing valve 58. At the same time the duct 84, will have been moved to apostion to open the connection between the pressure line 88 and the exhaust line 88, thus reducing the pressure throughout the entire system to the exhaust level, as determined by the setting of the exhaust pressure relief valve 'II (see Figs. 1 and 14).

In accordance with another feature of the present invention, there is provided a novel and improved control mechanism for operating the reversing valve to produce a certain and accurate reversal of the table at the end of its travel in each direction. As best shown in Figs. 1, 2 and 4, the reversing valve is controlled by means of a reversing lever II2 supported on a forwardly extending rock shaft H5. The reversing lever H2 is pivotally mounted for forward and back movement on a pin II4 carried on the rock shaft H5, 4 being normally held in a rearward position, in

which the offset upper end II8 will be located in the path of table dogs I20 and I22, by means of a spring-pressed plunger I24 mounted within the lever, and arranged for engagement with a lug I28 secured to the forward end ofthe rock shaft IIG. At its rear end the rock shaft H8 is provided with a downwardly extending lever arm I28 having formed at its lower end a slot ing valve member 68. The cam plate I30 for engagemenfwith a pin I32 on a cam plate I34 which is supported to turn on a pin I38 forming a forward extension of the revers- 34 is connected to control the operation of the reversing valve member 68 througha loose connection whlc is constructed and arranged to providea certain amount of lag in the movement of the reversing valve. This connection comprises a lever arm I40 secured to the reversing valve member 68, and having mounted thereon a pin I42- arranged to engage in-an elongated slot I44 in the cam plate I34, The cam plate I34 takes the form of an arrowhead cam having a V-shaped tip which is arranged for engagement with a follower roller I46 on a downwardly extending lever I48 pivoted at its upper end to an adjustable eccentric pin I50 .on the valve block 80, and at its lower end provided with a. contact Din I52. for engagement with a hydraulically actuated booster piston I54. set forth, the piston I54 is maintained by fluid pressure at all times in a fully advanced position to hold the lever I48 and follower I46 in contact with the arrowhead cam. I34.

The operation of the reversing lever and connections actuated thereby to effect the reversal of the table are as follows:

As the table reaches the .limitof its travel in either direction,' the reversing lever H2 is engaged by one or the .other of the dogs I20,-. I22, causing the arrowhead cam I34 to be rotated so that the follower I46 riding onto the tip portion of the cam, will operate to depress or retract the booster piston I54. Owing to the lost motion between the pin I42 and slot I44, the rotation of the reversing valve'member 68 will lag suflif ciently to prevent' the'closing 011- of the supply of pressure to one end of the cylinder 34 until after the follower I46 has passed the point or tip of the arrowhead cam. The booster piston .I54 actuated by fluid pressure now operates through the engagement of thefollower I46 with the arrowhead cam I34 to complete the movementof the arrowhead I34, reversing lever. H2 and reversing valve member 68 to their fully reversed position to start table movement in the opposite direction. I

In order to insure'the maintenance of the desired relative positions of the reversing valve member 68 and arrowhead cam I34 during reversal. and thus to insure the movement of the arrowhead past center position before the reversingvalve member has operated to fully close the pressure line to the feeding end of the cylinder 34, with a resulting possibility of stalling the table,'a friction drag is provided .to resist movement of the reversing valve member 68. As

. best shown in Figs. 4 and 6.0f the drawings, the

versing valve member 68 during reversal, to effect a smooth and accurate reversal in the direction oi table travel. These connections more specifically are constructed and arranged to permit the retraction of the piston by the reversing lever and arrowhead cam against a yieldingpressure,

As hereinafter more fully is arranged to admit additional sure, from a pressure line 248, hereinafter de-' and thereafter to advance the piston at a slow rate which may be readily adjusted in accordto insure a smooth pick-up of the table drive in the opposite direction. I

' drical bushing I10 for the piston I54. When the piston I 54 is moved to its fully retracted position, shown in Fig. 14, the port I68 is closed, liquid then passing along the-thread of the external screw threaded rear end of the cylindrical bushing I10, and thence through a radial groove I69 (see Fig. 2) into an expansion chamber I13 formed by the bushing I10 at the rear end ofthe piston I54. In this manner, a very slow admission of fluid pressure is obtained t'oinsure a relatively slow advanoe'of the piston I54 during the first portion of its upward stroke, while the'reversing valve is being fully closed oil to arrest further movement of the table, and while liquid pressure is being admitted to the cross feed-starting cylinder, as hereinafter more fully set forth. The rate at which the booster piston I 54 moves upwardly during this first portion of its. stroke is' further controlled by the adjustment of the needle valve I66. The. port I68 then opens, causing. the booster piston I54 to move upwardly at a somewhat fasterrate. The continued upward movement of the booster piston I54 operates to uncover a port I15 which fluid, under presscribed,- to still further increasethe rate of movement of the booster piston I54 to move the rebooster-piston I54 from the position at which the port I88 opens to the position at which the port I15 opens,:the reversing valve 68 remains fully closed ofl, so that a dwell period is provided in the table reversal which is determined by the rate of movement of the booster piston between these two positions. A screen I14 in the pressure line. I84 insures the removal of any impurities which might otherwise operate to obstruct the threaded portions I12 of.the feed line, to preventproper operation of the piston I54. I In order to. permit the retracting movement of the" piston I54 by the arrowhead cam I 34 as the reversing lever H2 is moved'by the engagement of the table dog, an exhaust connection I16 is provided to the pressure line I64 from the exings is provided with a crossfeed mechanism which may be of ordinary description, comprising a handwheel I 82 supported to turn with a rearwardly extending shaft I84 which operates through a screw and nutmechanism (not shown),,tomove the wheel spindle carriage 24,- toward and away from the lwork. flnasmu'ch as ance with operating conditions in themachine,

the details of thiscross feed mechanism form no part of the present invention, and may take the form of any one of several mechanisms well known in the art, no further illustration or description thereof is believed necessary.

In the preferred construction illustrated in the drawings, power actuation of the cross feed mechanism above outlined, is secured through connections which comprise a ratchet I86 formed on the periphery of the hand wheel" I82 which is arranged to be engaged by a pawl I88 on a pawl lever I90 which is connected through a link I82 to an adjustable crank arm I94 on a. rearwardly extending drive shaft I96. As best shown in Fig. 9 of the drawings, the shaft I96 is coupled to a shaft I98 which carries at its rear end one of two gears 200 and 202 of a gear type fluid motor 204.

In accordance with the present invention, valve mechanism is provided which may be rendered operative for controlling the admission of fluid to drive the fluid motor 204 either continuously as for plunge cut grinding, or intermittently to produce one reciprocation of the cross feed pawl I88 at each reversal of'table travel. The valve mechanism for controlling the operation of the cross feed fluid motor 204 comprises specifically a valve member 206 secured to the shaft I98, and arranged to turn within a valve casing 2I0. Associated with the valve 206 are two pressure inlet connections 2I2 and 2I4, the connection 2I2 having a port opening through the casing 2I0 in alignment with the valve 206 which, as best shown in Fig." 10, is provided with a high portion 2I6 adapted for one angular position of the shaft I98 and valve member 206 to close the pressure inlet 2I2. The pressure inlet 2 I4 is provided'with a port opening through the casing 2I0 which is located out of alignment with the valve member 206, and therefore, provides a continuously open passageway through the valve chamber designated at 2I3. Fluid pressure is admitted from the valve chamber 2I3 to drive the fluid motor gears 200 and 202 through a duct 2I8 (see Fig. 3).

The admission of fluid under pressure through ports 2I2 and 2| 4 and valve chamber 2'I3 is controlled by means of hydraulic connections which are constructed and arranged to control the operation of the cross feed motor to produce either an intermittent or continuous operation of the cross feed as desired. Fluid under pressure is admitted from the main pressure line of the machine through the inlet port 2I4 to produce a continuous operation of the cross feed motor. For intermittent operation of the cross feed, fluid pressure isadmitted from the main pressure line to the inlet port 2 I2, the pressure connection with port 2I4 being closed so that the cross feed motor can be driven through not more than one revolu-' tionbefore the supply of fluid pressure is cut off by the operation of the valve member 206. 'Hydraulic connections are provided, as hereinafter more fully set forth, for admitting at each reversal in the direction oftable travel, a limited amount of fluid under pressure through the valve port 2I4 which serves to turn the motor gears I and I02 and the valve member I06 sufficiently to uncover the port 2| 2.

The hydraulic connections through which the admission of fluid pressure to the cross feed valve ports 2I2 and 2I4 is controlled, include the selector valve 50 which takes the form of a valve member (see Figs. 2, 4. and 8) which is journalled in the lower casing block 96, and has formed therein a T-shaped duct 224 through which fluid pressure passes from the pressure line 48 to an axial bore forming a chamber 226 within the valve member 50, and for certain positions of the valve 50 to the main pressure feed line 52. At the rear end of the bore 226 there is formed a duct 228 which is arranged to connect alternatively with an intermittent cross feed port 230 (see Figs. 7, 8 and 9), a continuous cross feed port 232, or an exhaust port 234. Fluid pressure is directed from the port 230 through a feed line 236 to the intermittent cross feed port 2I2 associated with the cross feed motor valve 206. From the continuous feed port 232, fluid under pressure passes through a feed line 238 which is connected to admit fluid under pressure to the continuous feed port 2I4 of the cross feed motor valve 206. The exhaust port 234 opens into the main exhaust line I5.

The selector valve 50 above described, has three different operating positions which include a traverse grind position, a plunge cut position, and a stop position. In the traverse grind position specifically illustrated in Figs. 2, 4, 7, 8 and 9, fluid pressure is directed from the pressure line 48 through the T-shaped port 224 to the main distributing feed line 52 for driving the table 22, and through the bore 226 and duct 228 to port 230 and the cross feed fluid motor valve pressure inlet 2I2 for intermittentoperation of the cross feed. For the plunge cut grinding position, the selector valve member 50 is turned through 90 in a counterclockwise direction, shutting off the supply line 52 for driving the table and the intermittent cross feed port 230, and connecting the duct 228 to the continuous feed port 232, so that fluid pressure is admitted through pipe connection'238 to the cross feed valve pressure inlet 2I4. For stop position, the valve is turned through another 90, so that the pressure line 48 is again connected to the main supply line 52, while at the same time the duct 228 is brought into alignment with the exhaust port 234, thus reducing the pressure in the entire system to the relatively low value determined by the setting of the exhaust relief valve 11,

The duct 228 takes the form' of a throttle opening which is arranged to cooperate with the conin the rate of continuous cross feed. This adjustment is secured by controlling the exact angular position of the selector valve when set to the continuous feed position, in accordance with the calibrations on the selector valve adjacent the word continuous (see Fig. 5).

In the preferred form of the invention illustrated, hydraulic connections are provided which are rendered operative by the movement of the booster piston I54 at each reversal, to supply a limited amount of fluid under pressure through the inlet port 2I4 to the cross feed motor valve 206, so that the motoris turned through a suf flcient angle to open the pressure inlet port 2I2. The motor is then driven through substantially one revolution until the land 2I6 of the valve member 206 again operates to close off the port 2I2. The connections referred to comprise a starting cylinder 240 having mounted therein a piston 242 which is spring-seated against the inlet end of the cylinder by means of a compression spring 244.. Movement of the piston 242 against the pressure of its spring 244 causes fluid under pressure to be expelled from the starting cylinder through a port 246 into the continuous feed line 238 and inlet port 2I4 to the cross feed motor valve 206, thus causing the motor to be logged su'fllcientlyto uncover the inlet port '2l2, so that-the motor is rotated through one revolution as above described. -Fluid I pressure is admitted to actuate,the piston 242 upon actuation of the booster piston I54 through connections which include a supply line 248 and port 258 connecting with a chamber 252 formed by a reduced portion of the piston I54 and port 254, and pipe connection 256 connecting with the inlet end of the valve 240. The retracting movement of the booster piston I54 upon actuation of the reversing lever H2 and arrowhead cam. I34, operates to uncover the port 250. admitting fluid under pressure through the valve chamber :32 and pipe connection. 256 to operate the measuring valve piston 242 as above de scribed. As the piston I54 is again moved forwardly to itsnormal position to complete the operation of moving the reversing valve 68 'to its fully reversed position, the inlet port 258 is again closed, and fluid pressure is permitted to escape from the inlet. end of the valve 240 and pipe line 258 through the opening of exhaust port 258, so that the liquid is permitted to exhaust through chamber 252, port 258 and a pipe connection 268 to the main exhaust line I5.

As the piston 242 of the measuring valve 240 is returned to its normal position upon the opening of the pressure line 256 to exhaust, the exhaust end of the measuring valve 240 is refilled with liquid under pressure which is supplied through the intermittent cross feed, pressure line 235 and inlet port 2I2 to the cross feed valve chamber 2|; from which it passes in a reverse direction through the valve port 2 and pipe connection 238 back into the valve 240.'

It has been found under certain operating con ditions as, for instance, when the machine is first started, that the viscosity of the oil in the control system is likely to be greater so that a greater amount of-time will elapse upon each reversal before a suflicient amount of liquid can be forced through the screw thread I12 to move the piston I54 sufficiently to close off the supply of fluid pressure to the measuring valve 248 and to open the exhaust port 258. If this period lasts beyond the time required for one complete revolution of the cross feed motor 204, and the measuring valve member 242 has in the meantime been returned to its initial position by the admission of fluid pressure to the exhaust end of the valve 240, the closingbfi' of the inlet port 2I2 to the cross feed valve chamber 2I3 will operate to again actuate the measuring valve, and thus cause two or morerevolutions of the cross feed fluid motor to take place at each table reversal instead of one. In order to overcome this condition, a restriction indicated generally at 256 has been placed in the intermittent feed line 236,

so that a relatively slow operation of the piston |54 caused by any variation in the viscosity of the oil will be compensatedfor by a similarly slow admission of fluid pressure through the cross feed motor valve inlet 2 and chamber What is claimed is: 1. In a grinding machine having a rotary grinding wheel, a wheel support and a work support,

the combination of driving. and reversing mechanism for reciprocating one of said supports, a cross feed for imparting relative feeding movements to the grinding wheel and work compr is ing a ratchet and pawl, a rotary fluid motor connected to reciprocate the pawl, means including a pressure connection to the motor for continuously driving the motor to eifect a continuous .operation of said cross feed mechanism, and

connected to reciprocate the pawl, means ineluding a pressure connection to the motor for continuously driving the motor to eflect a con-' tinuous operation of said cross feed mechanism, means including a fluid pressure admission valve associated with the motor for imparting a limited rotational movement to the motor, and means controlled from said reversing mechanism to render said partial rotational means operative to ifect an intermittent operation of said crossfeed mechanism.

3. In a grinding machine having a rotary grinding wheel, a wheel support and a work support, the combination of driving and reversing mechanism for reciprocating one of said supports, a cross feed mechanism forimparting relative feeding movements to the grinding wheel and work comprising a ratchet and pawl, a rotary fluid motor connected to reciprocate the pawl, a fluid pressure connection to the motor for efiectlng an intermittent cross feed including a valve operable to close said connection to stop the motor at the completion of one reciprocation of the ratchet pawl, means controlled from the reversing mechanism for renderingtsaid intermittent cross feed connection operative to reciprocate the pawl, a continuous cross feed connection to the motor, and a selector device movable to render operative one or the other of said intermittent or continuous actuating connections for .the cross feed. 5

4. In a grinding machine having a rotary grinding wheel, a. wheel support and a work support,

the combination of driving and reversing mechanism'for reciprocating one of said supports, a

cross feed mechanism for imparting relative feeding movements to the grinding wheel and work comprising a rotary fluid motor, a rotary valve member driven by the motor, afluid pressure connection controlled by the valve member to admit fluid pressure to the motor during a portion only of thevalve rotating cycle, and means actuated by the reversing mechanism for starting the motor and valve member to open said fluid pressure connection.

5. In a grinding machine having a rotary grinding wheel, a wheel support and a work support, the combination of driving and reversing mechanism for reciprocating one of said supports, a cross feed mechanism for imparting relativefeeding movements to the grinding wheeland work comprising a rotary fluid motor aro tary valve'member driven by the motor, a fluid pressure connection controlled by the valve member to admit fluid pressure to the motor during a portion only of the valve rotating cycle, a pressure connection independent of said valve member for driving the motor, and means rendered operative at reversal for admitting a limited amount of fluid under pressure through said independent connection to start the motor and valve member.

6. In a grinding machine having a rotary grinding wheel, a wheel support and a work support, the combination of driving and reversing mechanism for reciprocating one of said-supports, a cross feed mechanism for imparting relative feeding movements to the grinding wheel and work comprising a rotary fluid motor, a rotary valve member driven by the motor, a fluid pressure connection controlled by the valve member to admit fluid pressure to the motor during a portion only of the valve rotating cycle, a pressure connection independent of said valve member for driving the motor, means rendered operative at reversal for admitting a limited amount of fluid pressure through said independent connection to start the motor and valve member, means for supplying fluid under pressure continuously to said independent connection, and a selector valve having alternative traverse grinding and plunge cut positions operable for the plunge cut position to supply fluid pressure continuously to said independent connection to the motor and for traverse grinding position to disconnect said continuous fluid pressure supply means.

7. In a grinding machine having a rotary grinding wheel, a wheel support and a work support, the combination of driving and reversing mechanism for reciprocating one of said supports, a cross feed mechanism for imparting relative feeding movements to the grinding wheel and work comprising a rotary fluid motor, a rotary valve member driven by the motor, a fluid pressure connection controlled by the valve member to admit fluid pressure to the motor during a portion only of the valve rotating cycle, a pressure connection independent of said valve member for driving the motor, means including a starting cylinder and piston connected to admit a limited amount of fluid under pressure through said independent connection to start the motor and valve member, means actuated by said reversing mechanism for actuating the piston,

spring means for returning the piston to its initial position, and a connection with said valve controlled pressure connection to reflll the starting cylinder.

8. In a grinding machine having a rotary grinding wheel, a wheel support and a work support, the combination of driving and reversing mechanism for reciprocating one of said supports, a cross feed mechanism for imparting relative feeding movements to the grinding wheel andwork comprising a rotary fluid motor, a

rotary valvemember driven by the motor, a fluid pressure connection controlled by the valve member to admit fluid pressure to the motor during a portion only of the valve rotating cycle, a second pressure connection independent of said valve member for driving the motor, and means actuated by-the reversing mechanism to start the motor and valve member including a starting cylinder. and piston connected toadmit a limited amount of fluid under pressure through said second connection to the motor, meansacting normally to maintain said piston in a retracted position, and a fluid pressure connection actuated by said reversing mechanism to advance the piston to start the motor.

9. In a grinding machine having a rotary grinding wheel, a wheel support and a work support, the combination of driving and reversing mechanism for reciprocating one of said supports, a cross feed mechanism for imparting relative feeding movements to the grinding wheel and work comprising a rotary fluid motor, a rotary valve memberdriven by the motor, a fluid pressure connection controlled by the valve member to admit fluid pressure to the motor during a portion only of the valve rotating cycle, a second pressure connection independent of said valve member for driving the motor, and means actuated by the reversing 'mechanism to start the motor and valve member including a starting cylinder and piston connected to admit a limited amount of fluid underpressure through said second connection to the motor, means acting normally to maintain said piston in a retracted position, a fluid pressure connection actuated by said reversing mechanism to advance tlie piston to start the motor, and a selector valve having alternative traverse grinding and plunge cut positions operable for the plunge cut'position to supply fluid pressure continuously to said independent connection to the cross feed motor, and for traverse grinding position to shut ofl the continuous supply of fluid pressure to said independent connection.

10. Reversing mechanism for the work support of a grinding machine comprising a motor for operating said. support, a reversing valve controlling admission of fluid to said motor, dogs on the support and a reversing lever actuated thereby, a cam associated with the lever, and a fluid actuated piston engageable therewith for continuing the movement of the reversing lever past central position, a lost motion connection between the lever and the valve to reverse the valve only upon movement of the lever and cam past middle position, means including a restricted inlet for moving the piston to continue the movement of the lever and valve to reverse position at a controlled rate, and means including a pres sure exhaust outlet to permit the retraction of the piston by the cam.

11. In a machine tool having a reciprocating support and a reversible hydraulic support drive mechanism, a reversing valve for said mechanism, a reversing lever, a cam connected to move with the reversing lever, and a fluid actuated piston engaging with the cam to continue the movement of the reversing lever past middle position, means including a restricted inlet for moving the piston to continue'the movement of v the lever and valve to reversing position at a controlled rate, and means including a check valve for exhausting fluid against a substantial pressure during retraction of the piston by the cam.

12. Reversing mechanism for the work support of a grinding machine comprising a motor for operating said support, a reversing valve controlling admission of fluid to said motor, dogs on the support and a reversing lever actuated thereby, a cam associated with the lever, and a fluid actuated piston engageable therewith for continuingthe movement of the reversing lever past central position; fluid pressure connections ior forcing the piston against the cam including a needle valve and a restricted pressure inlet in pressure during retraction of the piston by the cam.

13. In a grinding machine having a rotary grinding wheel, a wheel support and a work support, the combination of driving and reversing mechanism for reciprocating one oft said supports including a fluid motor for operating the support, a reversing valve for the motor, dogs on said reciprocable support, a reversing lever actuated thereby, a cam associated with the lever,-

and a fluid pressure operated piston engaging the cam for continuing the'movement of the lever past middle position, a .lost motion connection between the lever and the valve to reverse the valve only upon movement of the lever and cam past middle, position, fluid admission means for the piston constructed and arranged to permit the retraction of the piston by the cam, and thereafter for advancing the piston to continue the movement ofthe reversing lever and valve to reversing position, cross feed mechanism for imparting relative feeding movements to the grindin'g wheel and work comprising a rotary fluid motor, a rotary valve member driven by the motor, a fluid pressuraconnection controlled by the a valve member to admit fluid pressure to the motor during a portion only of the cross feed motor valve rotating cycle, and fluid pressure admission means rendered operative upon movement of the piston by the cam for admitting a limited amount of fluid under pressure to start the cross feed motor and valve member.

14. In -a grinding machine having a rotary grinding wheel, a wheel support and a work support, the combination of driving and reversing mechanism for reciprocating one of said supports including a fluid motor for operating the support,a.reversing valve for the motor, a flnid actuated plunger operable upon reversal to move the reversing valve to reverse position, a fluid pressure connection to the plunger having a re? striction therein for controlling the-rate of movement of the plunger, .cross feed mechanism for imparting relatiue feeding movements to the grinding wheel and work comprising a rotary fluid motor, a rotary valve member driven by the motor, a fluid pressure connection controlled by the valve member to admit fluid pressure to the motor during a portion only of the rotating cycle, a starting cylinder and piston connected to admit a limited amount of fluid under pressure to start the motor and valve member, a valve connection actuated by the movement of the plunger upon reversal for supplying fluid under pressure to actuate the piston and thereafter for exhausting fluid therefrom, springmeans operable during rotation of the motor and valve member for returning the piston to,itsinitial position and to re-flll the cylinder, said valve controlled pressure connection having formed therein a restriction to retard the rotation ofifthe cross feed motor and valve member to stop position during the move.- ment of the plunger and valve connection actuated thereby. e 15. In a grinding machine having a, rotary grinding wheel, a wheel support and a work support, the combination of driving and reversing mechanism for reciprocating one bfsaid sup-s ports including a fluidmotor for operating the support, a reversing valve for the motor, a reversing lever, a cam associated with the lever,-

and a fluid, pressure operated pistonengaging the cam for continuing the movement of the lever' past middle position, fluid admission means having a restriction therein for moving the pistonagainst the cam at a controlled rate, cross feed mechanism for imparting relative feeding moveing a rotary fluid motor, a rotary valve member driven by the motor, a fluid pressure connection controlled by the valve member to admit fluid pressure to the motor during a portion only of the rotating cycle, a starting cylinder and piston connected to admit a limited'amount of fluidunder ments to the grinding wheel and work comprispressure to start the motor and valve member, a

valve connection actuated by the movement of the plunger upon reversal for supplying fluid under pressure to actuate the piston and thereafter for exhausting fluid therefrom, spring means operable during rotation of the motor and valve member for returning the piston to its initial position and to re-flll the cylinder, said valve controlled pressure connection having formed therein a restriction to retard the rotation ofythe cross feed motor and valve member to stop position during thev movement of the plunger and valve connection actuated thereby.

for the machine havingmeans operable upon movement of the valve'from running to stop position to close the supply and exhaust connectionto one end of the cylinder to arrest support movement, and thereafter to connect both ends of the cylinder to pressure,- and further arranged in stop position to provide a direction connection between the pressure supply and exhaust connections.

l7. In a grinding machine having a rotary grinding wheel, a wheel support and a work support, the combination of driving and reversing mechanism for reciprocating one of said supports comprising a' driving cylinder and piston, a reversing valve and connections between the v'alve. and opposite ends of the cylinder, a by-pass connection between opposite ends of the cylinder, fluid pressure supply and exhaust connections to the reversing valve, and a starting and stopping valveforithe machine located in one of said con-- nections between the reversing valve and cylinder having ducts arranged for the running position of the valve to provide a passage for fluid-through one of said connections between the reversing valve and the cylinder, and to close said by-pass connection, for an intermediat position of said valve to close said connection from one end of the cylinder, and for the stop position of the valve to open said connection and said by-pass connection to the opposite end of the cylinder.

18. In a grinding machine having ,a rotary grinding wheel, a wheel support and a work support, the combination of driving and reversing mechanism for reciprocating one of said supports comprisingw, driving cylinder and piston, a' reversing valve and connections between-the valve and opposite ends of the cylinder, fluid pressure supply and exhaust connections to the reversing valve, a by-pass connection between opposite ends of the cylinder, and a starting and stopping valve for the machine located in one of said connections between the reversing valve and cylinder having ducts arranged for the running position of the valve to provide a passage for fluid through one of said connections between the reversing valve and the cylinder, and to close said by-pass connection, for an intermediate position of said valve to close said connection from one end of the cylinder, and for the stop position of the valve to open said connection and said by-pass connection to the opposite,end of the cylinder, and a second duct arranged for the stop position of the valve to provide a direct connection between the fluid pressure supply and exhaust connections.

19. In a grinding machine having a rotary grinding wheel, a wheel support and a work support, the combination of a reversible fluid pressure drive mechanism for reciprocating one of said supports including a fluid motor for operating the support, a reversing valve controlling admission of fluid to said motor, a cross feed mechanism for imparting relative feeding movements to the grinding wheel and work support comprising a rotary fluid motor, a rotary valve member driven by the motor, afluid pressure connection controlled by the-valve' member to admit fluid pressure to the motor during a portion only of the cross feed motor valve rotatingcycle, a second fluid pressure connection to the motor, a pressure connection independent of said valve member for driving the motor, means controlled by said reversing mechanism for admitting a limited amount of fluid pressure through said independent connection to start the cross feed motor and valve member, and a selector valve constructed and arranged for a traverse grinding position of the valve to supply fluid pressure to the reversing valve and support motor and to said cross feed rotary valve member, and for an alternative plunge cut grinding position of the valve to shut off the supply of fluid pressure to the support motor and to supply fluid pressure continuously through said independent connection to the cross feed fluid motor.

20. In a grinding machine having a rotary grinding wheel, a wheel support and a work support, the combination of a reversible fluid pressure actuated driving andreversing mechanism for one of said supports including a fluid motor, a reversing valve and connections for controlling admission of fluid to the motor, a cross feed mechanism for imparting relative feeding movementsto the grinding wheel and work support comprising a cross feed fluid motor, fluid pressure connections for continuously driving the cross feed motor to efi'ect a; continuous cross feed, .fluid pressure connections rendered operative by said reversing mechanism for intermittently driving said cross feed motor to effect an intermittent cross feed, and a selector valve including fluid pressure supply and exhaust connections thereto for controlling the admission of fluid pressure to each of said work support and cross feed motor connections arranged for plunge cut grinding position to connect said continuous cross feed connection to supply; for traverse grinding position to connect said intermittent cross feed and reversing valve connections to supply, and for stop position to connect said reversing valve and exhaust connections to supply.

21. In' a grinding machine having a rotary grinding wheel, a wheel support and work support, the combination, of a reversible fluid pressure actuated driving and reversing mechanism for one of said supports including a fluid motor, a reversing valve and connections for controlling admission of fluid to the motor, a cross feed mechanism for imparting relative feeding movements to the grinding wheel and worksupport comprising a cross feed fluid motor, fluid pressure connections for continuously drivingthe cross feed motor to effect a continuous cross feed, fluid pressure connections rendered operative by said reversing mechanism for intermittently driving said cross feed motor to effect an intermittent cross feed, and-a selector valve having a fluid pressure supply and exhaust connections thereto for controlling the admission of fluid pressure to each of said work support and cross feed motor connections arranged for plunge cut grinding position to connect said continuous cross feed connection to supply and for traverse grinding position to connect said intermittent cross feed and reversing valve connections to supply, said pressure supply connections including a throttle controlled by the position of the selector valve for throttling the supply to said continuous cross feed connection.

22. In a grinding machine having a rotary grinding wheel, a wheel support and a work support, the combination of driving and reversing mechanism for reciprocating one of said supports including a fluid motor for driving the support, a reversing valve movable to reverse the -flow of fluid pressure to the motor and having an intermediate dwell position, dogs on the reciprocable support and a reversing lever actuated thereby, a cam associated with the lever, a fluid actuated plunger engageable with the cam for continuing the movement of the reversing lever past middle position, means including a pressure exhaust outlet to permit the retraction of the plunger by the cam, and fluid pressure admission means operable for advancing the plunger at a slow rate to fully close the reversing valve, for continuing saidadvance at a faster rate tomove the reversing valve through dwell position, and for continuing said advance at a still faster rate to move the valve to fully reversed position.

23. In a machine tool having a reciprocating support and a reversible hydraulic support drive mechanism, a fluid motor for driving the support, a reversing valve controlling admission of fluid to said motor arranged for an intermediate position of said valve to fully shut off the supply of fluid to both ends of the motor, dogs on the support and a reversing lever actuated thereby, a cam associated with the lever and a fluid-actuated plunger engageable therewith for continuing the movement of the reversing lever past central position, a lost-motion connection between the lever and the valve to reverse the valve only upon movement of the lever and cam past middle position, means including a pressure exhaust outlet to permit retraction of the plunger by the cam, pressure admission means including a restricted inlet for moving the plunger to fully close the reversing valve, a second restricted inlet for continuing the movement of the plunger at a faster rate to move the reversing valve past dwell position, and a third inlet rendered operative for continuing the movement of the plunger at a still faster rate {or moving the reversing valve to full reverse posiion.

24. In a grinding machine having a rotary grinding wheel and a work support, the combination of driving and reversing mechanism for reciprocating the support including a fluid motor for driving the support, a reversing valve movable to reverse the flow of fluid pressure to the motor and having an intermediate dwell position, dogs on the support and a reversing lever actuated thereby, a cam associated with the lever, a fluid actuated plunger engageable with the cam for continuing the movement of the reversing lever past middle position, means including a pressure exhaust outlet to permit the \retraction of the .plunger by the cam, and fluid pressure admission means including a restricted inlet for advancing the piston to move the reversing valve to dwell position, and a second pressure inlet for thereafter advancing the piston at a faster rate, a cross feed mechanism for imparting relative feeding movements to the grinding wheel and work comprising a rotary fluid motor, a rotary valve member driven by the motor, a fluid pressure connection controlled by the valve member to admit fluid pressure to the motor during a. portion only of the rotating cycle, a starting cylinder and piston connected to admit a limited amount of fluid under pressure to start the motor and valve member, a valve connection in the plunger operable during the first stage only of the advance of the plunger for supplying fluid under pressure to actuate the piston and during the second stage in theadvance of the plunger for exhausting fluid from the piston, said valve controlled pressure connection having formed therein a restriction to retard the rotation of the cross feed motor and valve member to stopped position during the movement of the plunger and valve connection actuated thereby.

25'. In a grinding machine having a rotary grinding wheel, a wheel support, and a work suprate to move the reversing valve through dwell position, and for continuing said movement at a faster rate to move the valve to fully reversed position.

26. In a grinding machine having a rotary grinding wheel, a wheel support, and a work support, the combination of driving and reversing mechanism for reciprocating one of said supports including a fluid motor for driving the support, a reversing valve movable to reverse the flow of fluid pressure to the motor and having an intermediate dwell position, a reversing lever, a cam connected to move with the reversing lever and a driver engaging therewith for continuing the movement of the reversing lever past middle position, said driver having means associated therewith operable to advance the driver at a slow rate to fully close the reversing valve, for continuing said advance at a faster rate to move thereversing valve through dwell position, and for continuing said advance at a still faster rate to move the valve to fully reversed position.

27. In a grinding machine having a rotary grinding wheel, a wheel support and a work support, the combination of a reversible hydraulic support driving mechanism, a reversing valve for said mechanism, a reversing lever, a cam connected to move with the reversing lever, and a fluid actuated plunger engaging with the cam to continue the movement of the reversing lever past middle position, means including a pressure exhaust outlet to permit retraction of the plunger by the cam, and fluid pressure admission means operable to continue the movement of the. lever and valve to reversing position, a cross feed mechanism for imparting relative feeding movements to the grinding wheel and work comprising a rotary fluid motor, a rotary valve member driven by the motor, a fluid pressure connection controlled by the valve member to admit fluid pressure to the motor during a portion only of the valve rotating cycle, and a'second fluid pressure connection controlled by movement of said plunger for starting the motor and valve member to open said first-mentioned fluid pressure connection,

GEORGE -1 MAGLO'IT.

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