US2003269A - Automatic grinding machine - Google Patents

Description

May

H. AR TER' El AL AUTOMATIC GRINDING MACHINE Filed March 25, 1933 7 Shets-Sheet 1 INVENTOR ATTORNEY.

May 28, 1935. H. ARTER El Al.

I AUTOMATIC GRINDING mourns Filed March 25, 1933 7 Sheets-Sheet 2 lNg/ENTORS I BY H. ARTER ET AL AUTOMATIC GRINDING CHINE May 28, 1935.

Filed Marh 25, 1933 7 Sheets-Sheet 5 Y lNV NTORS Ma 28, 1935. H. ARTER EI'AL I 003,269

' AUTOMAflIG GRINDING momma 7 Sheets-Sheet 4 Filed March 25, 1933 .mn mm a m I M 7 TO R$,

' ATTORNEY.

. May 28,- 1935. H. ARTER El AL AUTOMATIC GRINDING MACHINE Fil'ed March 25, 1933 7 Sheets-Shet 5 Ill/Ila! INVEETOR 5 May 28; 1935. H. ARTER El AL 2,003,269 7 AUTOMATIC GRINDING MACHINE Filed March 25, 1933 7 Sheets-Sheet 6 INVENTORS W M Y y 8 1935. H. ARTER ET AL W 7 2,003,269

AUTOMATIC GRINDING MACHINE Filed March 25, 1933 7 Sheets-Sheet '7 INVENTORS .ATTORNEY,

Patented May 2a, 1935 UNITED STATES PATENT OFFICE,

Westboro, Maas.,

assignorstoArtei-Grlnding Machine Company, WorcestenMassq a corporation of Massachusetts Application March 25,

20 Claims.

This invention relates to automatic grindingv machines and is more especially concerned with machines of the general character disclosed in the Arter and Fraser Patent No. 1,888,710, grant- -5 ed November 22, 1932 and assigned to the assignee of the present invention. Y

The present invention aims to simplify the organization of machines of this general type and to adapt such machines for handling a wider range of work by making relatively simple ad- .iustments.

The nature of the invention will be readily understood from the following description when read in connection with the accompanying drawings, and the novel features will be particularly pointed out in the appended claims. v

In the drawings,

Figure 1 is a plan view of those parts of auinvention is more especially concerned;

Fig. 2 is a side elevation of the mechanism shown in Fig. 1; A

Fig. 3 is a view, partly in side elevation and partly in vertical section, illustrating more particularly'details of the turret construction and the manner in which it is mounted;

Fig. 4 is an end view of the parts. shown in Fig. 2; 1 30 Fig. 5 is a vertical, sectional view approximately on the line 5-5, Fig. 3;

- Fig. 6 is a vertical, sectional view through the machine;

Fig. 7 is a similar view through one end of the cylinder of the mechanism for reciprocating the turret;

Figs. 8 and 9 are views chiefly in vertical section of certain of the main valves for controlling the operations of the machine;

Fig. 10 is a transverse, vertical, sectional through the turret and the in therefor; v

Fig. 11 is a view similar to Fig. 10 but taken in a different plane I or the purposeof illustrating the piston valve associated acting on the turret; Figs. 12 and 13 are sectional and 'end views, respectively, of the clutch parts which are included 0 in the turret indexing mechanism;

Fig. 14 is a plan view, of the valve mechanismdirectly associated with the turret indexing piston and cylinder; I ,i

. Fig. 15 is a sectional view of said piston, cylin- I der and valves; and

view deiring mechanism tomatic grinding machine with which the present with the stop pawl for 1933, Serial No. 662,754

Fig. 16 isa-diagrammatic view of the fluid pressure system.

General organisation An understanding of the machine illustrated in the drawings will be facilitated by a brief description of its general organization and the functions which it performs. Referring more particularly to Figs. 1 and 2 it will be observed that the machine includes a grinding wheel 2 and a 10 turret 3 carrying a series of chucks or colletts l for holding articles of work while the grinding wheel 2 acts on-them. The machine is adapted more especially for operationon rolls, pins, poppet valves, and similar articles where the grind- 1 ing operations are to be performed upon the end portion of each article of work. Consequently, a loading mechanism of any suitable type is providedfor the purpose of forcing apiece of work into each chuck as it arrivesin loading position, 2 an additional mechanism rotates the turret intermittently or indexes it to move the chuck-successively through their diflerent podtions, in-- cluding particularly the loading and working poturret are performed hydraulically or through some other type of fluid actuated mechanism. Preferably, also, the chucks are similarly operated. The indexing operation involves not only the rotative movement of the turret but the gradso ual arresting of that movement without undue jar or strain on the parts and the locking of the turret in its indexed position. At the beginning of the grinding operation on each piece of work the wheel 2 is moved toward the chuck located 85 in working position and at the completion of this movement it remains stationary, empt for its rotary motion, while the entire-turret is moved in .a direction parallel to the axis of the grinding wheel to traverse the work across the face of the 40 wheel.

.Wheel head structure and operating mccha therefor The grinding wheel I is mounted in suitable bearings. carried by a wheel slide I, Fig. 1. the shaft 6/0! the wheel being\belt connected or driven in any other way from a suitable of power. For the purpose of giving the eel the movements above described toward and the work, theslide i is mounted to reciprocate in the frame of the machine and an operating mechanism substantially like that shown in the Fraser Patent No. (1,873,751, granted August 23, 1932, is provided. This mechanism is operated 65 sitio'ns. Preferably all of the movements of the g5 by a cam il, Fig. 6, on the cam chaft i8, both of these parts corresponding to those designated by the same numerals in the patent just mentioned. This operating mechanism is so designed that it moves the wheel 2 in rapidly toward the work during the first part of the approachin movement, then completes this movement very gradually, and finally moves the wheel quickly away from the work again when the grinding out operation has been completed. I

Turret indexing mechanism The turret 3 is mounted in suitable hearings to revolve around a horizontal axis and it carries the four equally spaced chucks 4 previously mentioned. For the purpose of producing the indexing movement it is encircled by a worm. wheel 8, Fig. 10, secured rigidly thereto and arranged to be driven by a worm 9 keyed on a horizontal shaft III which extends under the turret transversely thereto. At one end this shaft carries a pinion l2 which meshes with a gear it fast on the end of a horizontal shaft I. At predetermined times'in each cycle of operations of the machine this shaft is revolved by a fluid actuating mechanism best shown in Figs. 10 and 15. It comprises a trunk piston I! mounted to reciprocate horizontally in the bore of a cylin der block it. At one side this piston is cut away and has a rack l5 secured to it which meshes with and drives a pinion I! which is secured to, or is made integral with, a hollow pinion l9.

shaft 29 through which the shaft ll extends.

In order to control the driving connection between the piston and the turret, a'clutch, which is indicated in general at 2!, is interposed between the two shafts i4 and 20. It consists. as best shown in Figs. 12 and 13, of a flange 22 rigid with the shaft 20 and provided with two lugs 23 projecting axially therefrom and adapted to enter slots 24 formed in a circular flange 25 which projects'axially from the right-hand face of the gear l3. Due to this'co'nstruction the clutch can be engaged in one position only of the two shafts. A spring 26, Fig. 10, acts on the shaft I in a direction tending to slide it toward the right, Fig. 10, and thus to hold the clutch parts in operative engagement with each other, in which condition the gear II will be connected positively with the hollow shaft 20 and The movements of the trunk piston I! are controlled by a main valve mechanism operated by cams on the cam shaft l8, previously referred to, and which presently will be described more in detail, but the clutch 2! is controlled by a secondary or auxiliary valve under-the control of one of the main valves and indicated in general at D.' This valve is of the piston type and the piston rod 21 is extended, as shown in Fig. 10, and arranged to operate a bell crank lever 28,

the lower end of .which is forked to straddle a collar 30 secured on the end of the shaft l4, two pins or rolls carried by the lever entering the groove in the collar. The movementof the trunk piston ii in one direction only is utilized to index the turret, its movement in the opposite direction being simply an idle return movement preparatory to performing the next indexing operation. The main control-valve which governs the movements of this piston is so connected with the secondary valve D that it controls its operations also and its movements are so timed that it dlsenga'ges the clutch at the completion of the indexing movement and causes aooasee it to re-engage again at the beginning of the next indexing movement, the idle return stroke of the piston taking place in the meantime. The mechanism just described is so timed that one complete revolution of the gear l3 completes an indexing movement of the turret, or, in other words, moves the 'turret through an angle of 90.

- As above stated, it is necessary to bring the turret to a stop in a deflnite position atthe end of each indexing movement, and for this purpose a stop pawl 3|, Figs. 10 and 11, is provided and is arranged to enter any one of four recesses or notches 32 formed in a cam ring 33 which encircles the turret and issecured rigidly thereto. This pawl is fulcrumed on a lug projecting from the cylinder block i6 and is connected by a link St to a lever 35. A spring 35 acts on this link to hold the pawl in its turret locking position. It may be moved out of this position, however, by means of a piston valve, indicated in general at E, which is under the control of one of the main valves operated by a cannon the main cam shaft l8. It will be evident from an inspection of Fig.

11 that if fluid under pressure is delivered to the left-hand end of the cylinder E it will force the piston to the right, thus operating through the connections just described to swing the pawl out of the notch 32 in which it is located, leaving the turret free to be rotated by the indexing mechanism. This action occurs immediately prior to the commencement of each indexing movement.

Control mechanism valve c is extended through the cylinder head and bears against the end of a lever ll carrying. a roll which runs on the periphery of the cam II. The cam operated lever thus oppom the action of the spring. Each of the other valves A and B is operated in the same manner. -All of these valves are essentially alike except for the arrangement' of the. ports, such arrangement being determined by the functions required of the respggtive valves.

Each of the valves D and E is of a similar construction in that it includes a piston which is slidable in a cylinder, controls properly spaced and dimensioned ports, and is normally held against one end of the cylinder'by a spring. Each of these valves, however, is arranged to be operated by fluid admitted through one of the main. valves to the end of the cylinder opposite to the spring.

The general arrangement of the hydraulic system will be readily understood from an inspection of Fig. 16. This system includes a supply tank 42 for the oil or other fluid used, a pump 43' -for taking oil from the tank and forcing it under pressure to the various units of the system, a

observed'that the main valve A controls the supply of oil to the secondary valve D which, as previously stated, operates the clutch. Through this arrangement the valve A exercises a joint control with the valve D over the starting and stopping of the indexing movement. The main valve B controls the operation of the valve E which, as above stated, operates the pawl Ii.- Both the valves D and E are connected with the opposite ends of the turret indexing cylinder it 1 through suitable piping. .The arrangement is such that oil under pressure can be forced into either end of the cylinder, as desired, for the purpose of reciprocating the piston II, both the inflow of oil and the discharge of'the exhaust oil being maintained under control so that the rate of movement of the piston is properly governed.

A shunted check valve 45 is included in the conpiston is toward the right. During this movement the oil discharged from the cylinder i0, flows through the valve E around the neck of the piston and then through the valve D, the piston of which at that time is at the upper limit of its stroke, and back to the supply tank 42. Oil under pressure now flows through the valve D into the left-hand end of the cylinder. At this time the pressure ports of the valve A are closed but the valve B is admitting oil to the secondary valve E, thus acting to hold the pawl 3| out of the notch 32. After the indexing movement has started, the valve B is moved to permit the ex-.'

haust of the oil from the secondary valve E, but there is no pressure on the piston of this valve at this time tending to reverse it due to the fact that the'roll on the end of the pawl 3| is riding on the raised surface of the cam 33. As soon as the indexing movement has proceeded far enough to allow the roll to start down the incline into the next notch 32, the spring 36, Fig. 11, acts both to force the pawl into its notch and'also to move the piston Al in the valve E toward the left, Fig. ll,'where it will begin to close the ports 48 through which the oil expelled from the cylinder.

36 is being forced. This movement of the valve is under the control of the cam rotating with the turret, and the cam is so designed and the parts are so adjusted that the motion of the turret is decelerated upon the entrance of the roll 46 into the notch 32 at such a rate that it is moving at a very slow speed when it is finally stopped by the pawl.

After the indexing operation has been completed, and prior to the initiation of the next indexing movement, the clutch II is disengaged and the piston l5 makes its return stroke. The range of movement of this piston and the points at which its movements terminate may be determined by the adjusting screws threaded through the cylinder heads, as shown in Fig. 15.

Turret reciprocating mechanism N, Fig. 3. which is supported in suitable ways on the machine base or frame I, and a fluid actuating mechanism is provided tomove the slide Il backward and forward on said ways. This mechanism comprises a cylinder F, Figs. 6 and 16, mounted on a bracket that is secured rigidly to one side of the machine frame. A piston I3 slides in said cylinder and is secured rigidly to a rod 54 which is fastened to the slide 50 by means of a screwtlireaded adjusting mechanism of a well known type arranged to be'operated by a hand wheel '55. The flow of fluid to and from the cylinder F is controlled by a valve C arranged to be operated by the cam on the cam shaft II. It

admits oil under pressure, first to one end and then to the other, of the cylinder and thus operates through the connections just described to slide 50 take place rapidly while the working or grinding stroke should be made relatively slow. Accordingly, the oil conducting pipe 56, which connects the right-hand end, Fig. 6, of the cylinder F with the main control valve 0, is arranged to discharge into a passage Il, Fig. 7, having communication with the cylinder F both through a check valve 58 and also-through an adjustable needle valve 60. Consequently, when oil is being forced under pressure through the valve C and pipe 56 to the passage Bl, it flows freely past the check valve 58 into the right-hand end of the cylinder F and produces a quick return movement of the piston and slide. An instant later this supply of oil is cut off by the valve C and oil then is admitted through the pipe I, Fig. 6, to. force the piston in the opposite direction. The oil in the right-hand end of the cylinder cannot escape through the check valve and finds an outlet only through the needle valve. Consequently, by properly adjusting this valve the speed of the grinding movement can be varied within relatively wide limits.

'It should be noted that all of the parts for operating the turret and the chucks are mounted on the slide Bl so that the entire turret operating mechanism is reciprocated with the turret and the relationship of this mechanism to the turret is not disturbed by the reciprocating movement. It may also be pointed out that both the turret and its supporting and operating mechanism are all mounted on. a plate 62, Figs. 1, 3 and 6, which is connected with the slide 50 by a pivot pin 83 and by bolts that extend through slots 83-46, Fig. 1,

Chuck construction and operation While chucks of any suitable type can be used in the machine, and the nature of them neces; sarily will be determined by the requirements of different articles of work, chucks of the general type shown in the Fraser and Arter patent above mentioned are welladapted for use in this machine when it is employed for grinding the ends of rolls, pins, and the like. Each chuck includes an expansible work holder 65, Fig. 3, mounted in a suitable barrel and associated with a slidable plunger 88 that is urged rearwardly by a spring 81. Slidably mounted inside the plunger 8 is an ejector II arranged to be operated by a coiled spring II. This whole chuck body i mounted on roller bearings to revolve rapidly in the chuck barrel I2 thatis clamped securely in the turret.

the purpose of closing the chuck a fluid actuatedmechanism is provided. comprising a flexible bellows l3 -mounted in the hollow body or cylinder H which is secured rigidly to the-endofthe chuck body.- When fluid under pressure is admittedto this cylinder it collapses the bellows and moves the plunger 86 forward, thus forcing the externally taperedsurfaces of the work holder 55 outwardly in contact with the internally tapered surfaces of the nose pieces 68 of the chuck. This contracts the work holder suihciently to cause it to clamp an article of -work positioned in it. A light coiled spring-l6 is interposed between the cylinder 14 and the-chuck body to take up constantly any lost.motion in the hearings, or, in other words;v to keep the roller bearings under a slight load. Obviously the bellows 13 could be replaced by a piston and such a construction is sometimes used;

.Thelpressure actuatedmechanism of all four chucks is under the control of a single valve G located at the end of the turret-and in axial alinement with the turret. It comprises a spider-like valve body having four armswhich are secured to-connectors Tl projecting rear'wardly from the ends of the cylinders 14, and an oscillating tapered-.valve plug ii fittingina central, hole in said body. Oil under pressure is conducted from the pump 43, Fig. 16, through'a flexible pipe I8, Fig. 2, to they lower or inlet chamber 88,-Fig. 3,

- of the-valve G, while another pipe 81 carries the exhaust oil away from theoutlet chamber 8!.

In this machine the loading mechanism is arranged to force an article of work into each chuck as it arrives in'the position indicated at'l' in Figs.- 1 and 5. It will be seen from an inspection of these figures that the inlet and outlet chambers in the valve G are so positioned as to maintain pressure normally on the chuck which is in grinding or working position and also on that immediately following it, but that no pressure is maintained-on eitherthe chuck in loading position oron the uppermostchuck shown in these two figures. Immediately after a piece has been leaded into the chuck 4'- the indexing movement starts and it carries the piece of work just forced into the chuck away from the loader and behind a guard 83, Fig. 1, which prevents the ejector plunger ,1! from.f orcing thearticle out of the chuck. Atthe end of the guard 83 is a positioning roller intocontact with .which the end of the work is carried immediately after leaving the guard and which serves to force the work backwardly so that its end projects into a fixed and predetermined position. This action occurs approximately as the .chuck arrives at the end of an indexing movement. At the end of the indexing operation theiyalve plug II is rotated backwardly far enough apply pressure to the chuck in which the vorbhgs just been positioned by the roll at, andglater, during the indexing operation, it is swung forwardagain, i, e., with the direction of'rotation of the turret, in order to clamp this piece ofwork securely and also to release the finishedplece of work held in the lowermost chuck.

Fig. 5 shows the valve plug in the position which it occupies at the end of the indexing movement and just before. beginningits backward swing. For the purpose of operating .the valve in this manner and in timed relationship to the indexing 75, movement, valve plug I6 is connected by a link 85; Figs. 1 and 2, with an arm 88 secured rigidly on the rock shaft ll. Another arm ll also secured to this rock shaft carries a roll running in the-groove of a cam 80' which is secured fast on the hollow shaft 2G that is revolved directly by the'trunk piston I5. Since this piston produces the indexing movement. the timing of the operation of the valve 6% with reference to said movement can be made very accurate by the arrangement just described.

It will be observed that since the movement of the valve IS in a clockwise. direction, Fig. 5, is coincident with the indexing movement of the turret, the'port 80 in said valve will move in such a manner that pressure will always be maintained upon a chuck holding an article of work during the entire period in which said chuck travels from the grinding position to the discharging position. In fact, the work is not released until the valve I6 is rocked in a counter-clockwise direction, Figs. 2 and 5, following the completion of the indexing stroke. Upon the backward or counter-clockwise movement of the valve it the discharge port 82 is brought into communication with the port leading to the chuck then in discharging position and thus relieves the pressure on the bellows "i8, permitting the spring -37 to open the chuck and release the work. The

ejector 10 immediately forces the work out of the chuck so that it is empty when it arrives at the loading station. lihus any possibility of diacharging the work while 1th within the none of operation of the grinding wheel is prevented, and its discharge is permitted only after the chuck has arrived at the extreme lowermost position of its range of movement.

For the purpose of revolving each chuck while it is in its working position the cylinder M of that it is not driven. at this time.

In this machine the loading operation may conveniently be performed hydraulically, and a cylinder H, Fig. 16, is provided for this purpose, this cylinder being connected with one of the main control valves A which, as above stated, is the valve that operates the turret clutch, Figs. 12 and 13. Any suitable mechanism may be provided for delivering the work to the loader, such, for example, as the chute 94, Fig. 1. Usually the loading operation consists simply in forcing an article of work endwise into the open chuck against the pressure of the ejector.

The hydraulic system is subject to fluctuations in pressure due to sudden demands placed upon it, and in'order to avoid any possibility of having the work ejected from the chucks because of some sudden but temporary drop imiluld pressure, the

supply pipe leading to the valve G is equipped with a check valve OI, Fig. 16, which prevents return flow of the fluid-through this supply line, and a pressure stabilizing or compensating device 98 is connected to the line between this check valve and the valve G. This device may'consist simply of a cylinder with a spring pressed piston mounted in it, thespring being fully compressed when the pressure is normal, but expanding and forcing the piston forward immediately when drop in pressure occurs. The cylinder holds a.

considerable body of oil so that it will serve to maintain pressure on the chucks for a substantial interval of time during which sub-normal pressure may exist in other parts of the system.

Operation The operation of the machine and the relativ timing of the functions of its various units have been so completely set forth in connection with itself readily to re-tooling to adapt it for different articles of work.

While we have herein shown and described a preferred embodiment of our invention, it will be understood that this disclosure has been made rather by way of illustration than limitation and that the invention is susceptible of embodiment in other forms without departing from the spirit or scope, thereof.

Having thus described our invention, desire to claim as new is:

1. In a grinding machine, the combination of a turret carrying a series of work supporting chucks, a grinding wheel for acting on the work what we supported in said chucks, means for indexing said turret to bring said chucks successively into working and loading positions, fluid actuated mechanism for operating said chucks, andcontrolling means for said mechanism operative to cause the chuck leaving the working position to remain closed and to close the chuck approaching said position while leaving the chuck at the loading position open.

2. In a grinding machine, the combination of a turret carrying a series of work supporting chucks, a grinding wheel for acting on the work supported insaid chucks, fluid actuated mecha-' nism for indexing said turret to bring said chucks successively into loading and working positions, a fluid actuated operating mechanism associated with each individual chuck for controlling the clamping and releasing of the work, an oscillating valve common to all of said fluid actuated chuck operating mechanisms for controlling their operation, and means for oscillating said valve during the indexing movement, and subsequently returning said valve to its normal position again preparatory to the next indexing movement.

3. In a grinding machine, the combination of a turret carrying a series of work supporting chucks,

' a grinding wheel for acting on the work supported in said chucks, fluid actuated mechanism for 'indexing said turret to bring said chucks successively into loading and working positions, a fluid actuated operating mechanism associated with each individual chuck for controlling the clamp-' ing and releasing of the work, an oscillating valve common to all of said fluid actuated chuck operat-- ing mechanisms for controlling their operation, and connections between said valve and said indexing mechanism for oscillating the vali re in a definite timed relationship ments of the turret.

4. In a grinding machine, the combination of a turret carrying a series of work supporting chucks, a grinding wheel foracting on the. work supported in said chucks, fluid actuated mechanism for in dexing said turret to bring said chucks successively into loading and working positions, a fluid actuated operating mechanism associated with each individual chuck for controlling the clamping and releasing of the work, an oscillating valve common to all of said fluid actuated chuck operating mechanisms for controlling their operation, a slide on which said turret is mounted,

to the indexing move-'-- means supporting said slide for reciprocating movement, fluid actuated mechanism for reciprocating said slide, and controlling means for automatically eflecting the operation of all of said fluid actuating mechanisms in definite timed relationship to each other. 1

5. In a grinding machine, the combination of a turret carrying a series of work supporting chucks, a grinding wheel for acting on the work supported in said chucks, fluid actuated mechanism for indexing said turret to bring said chucks suc- 5 oessively into loading and working positions, a fluid actuated operating mechanism associated witheach individual chuck for controlling the clamping and releasing of thework, an oscillating valve common to all of said fluid actuated chuck operating mechanisms'for controlling their operation, a slide on which said turret, together with said fluid actuated mechanisms and said valve are mounted, means supporting said slide for reciprocating movement, fluid actuated mechanism for reciprocating said slide, and controlling means for automatically effecting the operation of all of said fluid actuating 'mechanisms in definite timed relationship to each other.

6. In a grinding grinding wheel; mea for driving said wheel; a turret carrying a plurality of chucks each adapted to support a piece of work for the operation thereon of said wheel; fluid actuated mechanism for inhine, the combination of a 40 dexing said turret to carry. the chucks successive- 1y into different operative positions including a working position and a loading position; said mechanism comprising a cylinder, a piston working therein, means for transmitting the movements of said piston to said turret to rotate the turret intermittently; fluid operated valve means for controlling the admission of fluid under pressure to said cylinder and the escape of fluid therefrom, and a primary controlling mechanism for operating said valve means. i 5 7. A machine according to preceding claim 6 including a clutch controlling the operative connectlon between said piston and said turret, and means under the control of said. primary controlling mechanism for operating said clutch at pre- 0 determined points in each cycle of operations of the machine.

8; In a grinding machine, the combination of a grinding wheel; means for driving said wheel;

a turret carrying a plurality of chucks each adaptcluding a working position anda loading position; said mechanism comprising a cylinder, a piston working therein, a shaft arranged to be revolved by the movement of said piston, a worm carried by said shaft, and a worm wheel revolving with said turret and driven bysaid worm; and

valve mechanism operated in timed relationship to other operations of the machine for controlling the rate of movement of said piston in said cylinder.

9. In a grinding machine, the combination of a grinding wheel; means for driving said wheel; a turret carrying a plurality of chucks each adapted to support a piece of workfor the operation thereon of said wheel; fluid actuated mechanism for indexing said turret to carry the chucks successively into difierent operative positions including a working position and a loading position; said mechanism comprising acylinder, a piston working therein, means for transmitting the movements of said piston to said turret to rotate the turret intermittently; a main valve mechanism for controlling the rate of movement of said piston in said. cylinder; a stop device for locking said turret in its indexed position, and fluid pressure actuated means connected with said stop device to operate it, the last mentioned means comprising a. secondary valve under the control of said main valve mechanism and cooperating with it and with said stop device to decelerate the movement of the turret and to bring the turret gradually to a stopat the end of its indexing movement.

10. In a grinding machine,- the combination of a grinding wheel; means for driving said wheel; a turret carrying a plurality of chucks each adapted to support aa-piece of work for the operation thereon of said wheel; fluid actuated mechanism for indexing said turret to carry the chucks successively into different operative positions including a working position and a loading position;

. said mechanism comprising a cylinder, a piston working therein, means for transmitting the movements of said piston to said turret to rotate the turret intermittently, and a clutch for controlling the operative connection between said piston and said turret; fluid actuated mechanism for operating said clutch; and means for controlling the operations of said fluid pressure actuated mechanisms in timed relationship to each other and to causesaid clutch to transmit the movements of said piston in one direction onlyto said turret, said controlling means including cam operated main valves and fluid operated secondary valves under the control oi. said main valves, cooperating both to control the direction of movement of said piston and also to bring the piston gradually to rest at the end of its indexing stroke.

11. In a grinding machine, the combination ofa turret carrying a series of work supporting chucks, a grinding wheel for acting on the work supported in said chucks, fluid actuated mechanism for indexing said turret to bring said chucks successively into loading and working positions, a fluid actuated operating mechanismassociated with each individualchuck for controlling the clamping and releasing or the work, an oscillating valve located at the end of the turret and com- -mon to all of the latter fluid actuating mechanisms for controlling their operations, said valve being constructed to normally maintain the chuck in working position closed and that. in loadin position open, mechanism for automatically oscillating said valve in timed relationship to each indexing movement of the turret to hold the chuck in working position closed while it swings away from the latter position but to open it when in reaches a discharging point, and to close each chuck into which work has just been loaded before the latter chuck arrives in working position.

12. A machine according to preceding claim 11 inwhich the connections for transmitting movement from said piston to said turret includes a clutch, and a fluid actuated mechanism under the control of said valve mechanism for operating said clutch at approximately the beginning and the end of each indexing movement.

13. In a grinding machine, the combination of a grinding wheel; a turret carrying a plurality of chucks each adapted to support a piece of work for the operation thereon of said wheel; fluid actuated mechanism for indexing said turret to carry the chucks successively into different operative positions including a working position and a loading position; a stop pawl cooperating with said turret to arrest the movement of the turret at the end of each indexing operation; a piston valve for operating said pawl; a main valve mechanism for controlling said indexing operation and the operation of said piston valve, said turret having a plurality of cam elements thereon for engaging said pawl; and connections between'said pawl and said piston valve for operating the latter valve to cause it to exercise a control over the operation of said fluid actuated mechanism.

14. In a grinding machine, the combination of a grinding wheel; a turret carrying a plurality of chucks each adapted to support a piece of work for the operation thereon of said wheel; fluid actuated mechanism for indexing said turret to carry the chucks successively into diflerent operative positions including a working position and a loading position; each 0! said chucks'including relatively movable jaws for gripping the work, a spring normally serving to hold said chuck open and parts arranged to be actuated by fluid pressure for closing said chuck; means in the turret for supporting said chucks for independent rotation about axes parallel to each other and to the axis of rotation of the turret; a valve mounted at the end of said turret to swing about the axis of the turret; and connections for causing said valve to control the flow of fluid under pressure to said chucks to operate them at the desired times.

15. In a grinding machine, the combination of a turret carrying a plurality of work supporting chucks, a grinding wheel for acting on the articles of work supported in said chucks, and fluid actuated mechanism for indexing said turret to bring said chucks successively into grinding position, said mechanism being constructed and arranged to move said turret rapidly during a portion of each indexing movement and including means under the control of the turret for decelerating the motion of the turret to bring it gradually to a stop at the end of said indexing movement,

16. In a grinding machine, the combination of a turret carrying a series of work supporting chucks, a grinding wheel for acting on the work supported in said chucks, fluid actuated mechanism for indexing said turret to bring said chucks successively into loading and working positions,

a fluid actuated operating mechanism associated plied to said chuck operating mechanisms ap- 315 ing with the turret and cooperating with said proximately unaffected by a temporary drop in the pressure in the main fluid supply system.

17. In agrinding machine, the combination of a grinding wheel; means for driving said wheel, a turret carrying a plurality of chucks each adapted to support a piece of work for the operation thereon of said wheel; fluid actuated mechanism for indexing said turret to carry the chucks successively into different operative positions including a working position and a loading position; said mechanism comprising a cyl-' inder, a piston working therein, and means for transmittinglthe movements of said piston to said turret to rotate the turret intermittently; valve means for controlling the admission of fluid under pressure to said cylinder and the escape of fluid therefrom, mechanism for operating said valve means, a clutch controlling the operative connection between said piston and said turret, and an auxiliary cylinder and piston under the control of said valve means for operating said clutch.

18. In a grinding machine, the combination of: a grinding wheel; means for driving said wheel, a turret carrying a plurality of chucks each adapted to support a piece of work for the operation thereon of said wheel; fluid actuated mechanism for indexing said turret to carry the chucks successively into different operative positions including a working position and a loading position; said mechanism comprising a cylinder, a piston working therein, and means for transmitting the movements of said piston to said turret to rotate the turret intermittently; valve means for controlling the admission of fluid under pressure to said cylinder and the escape of fluid therefrom, mechanism for operating said valve means, and a cam secured to and revoiw valve means to so control the fiow of the actuating fluid that the turret will be brought to rest gradually at the end of each indexing movement.

19. In a grinding machine, the combination of a turret carrying a series of work supporting chucks, a grinding wheel for acting on the work supported in said chucks, mechanism for indexing saidturret to bring said chucks successively into loading and working positions, a fluid actuated operating mechanism associated with each individual chuck for controlling the clamping and releasing of the work, a valve comprising a valve body rigid with said turret and having ports communicating with said respective chuck operating mechanisms, said valve also including a valve plug around which said valve body is rotatable,

and connections between said valve plug and said indexing mechanism for oscillating the plug in a definite timed relationship to the indexing movements of the turret.

20. In a. grinding machine, the combination of a turret, a plurality of work supporting chucks mounted in said-turret for rotation about their respective axes, a grinding wheel for acting successively on the articles oi work supported in said chucks, fluid actuatedmechanism for indexing said turret to bring said chucks successively into grinding and loading positions, mechanism for operating said chucks to cause them to grip and release the work at the desired times in the cycle of operations of the machine, and mechanism for relatively moving said grinding wheel and said turret to produce a traversing movement of the wheel on the work in a direction transversely to the axes of rotation of the respective chucks.

HARRY ARTER. WARREN F. FRASER.

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