US1233670A

US1233670A - Grinding-machine.

Info

Publication number: US1233670A
Application number: US14741717A
Authority: US
Inventors: Tom H Jarvis
Original assignee: Individual
Current assignee: Individual
Priority date: 1917-02-08
Filing date: 1917-02-08
Publication date: 1917-07-17
Anticipated expiration: 1934-07-17

Description

T. H. JARVIS.

GRINDING MACHINE.

APPLICATION FILED FEB. B. 1912.

Patented July 17, 1917.

4 SHEETSSHEET 1.

' INVENTOR JZZr/z 6'.

WITNESSES i; Q- b T. H. JARVIS..

GRINDING MACHINE.

1,233,670. MPHCATION FILED FEB. 8, 1.9M. Patentefi l7 I V 4-$HEETSSHEET 2.

' INVENTOR fem,

WITNESSES AZLZErIQ5.

' ATTORNEY TLH. JARVIS. GRINDING MACHINE.

Patented July 17, 1917.

4 QIEETS-SHEET 3 1 M I nm E. E. F D E L H N o n A c U P DI A I.- O 7 6 3 3 '2 I 1 INVENTOR ATTORNEY WITNESSES (5 22 11. W'JJ. W

T. H. mavqs. GRlNDHG MACHINE.

APPLICATION FILED FEB. 8. 1917- Patented July 17, 1917.

4 SHEETS-SHEET 4-- UNITED STATES PATENT OFFICE.

TOM I-I. JARVIS, OF HUNTINGTON, WEST VIRGINIA.

GRINDING-MACHINE.

Application filed February 8, 1917.

To all whom it may concern:

Be it known that I, TOM H. JARVIS, a citizen of the United States, residing at Huntington, in the county of Cabell and State of West Virginia, have invented certain new and useful Improvements in a Gririding-Machine, of which the following is a specification.

This invention relates to grinding machines, and more particularly to a machine specially adapted for grinding table glasses and similar articles.

One of the main objects of the invention is to provide a machine of the character stated of comparatively simple construction and operation in which a cooling liquid, such as water, is continuously supplied to the grinding element during the grinding operation, the supply of water being cut off simultaneously with the cessation of the grinding operation. Another object is to provide a machine having a grinding head and a work-holding head, together with means for normally forcing the workholding head toward the grinding head, this means being adjustable so as to vary the pressure exerted on the article being 0perated upon thus rendering itpossible to adjust the machine to suit articles of different textures. Another object is to provide a machine having means for automatically removing the work from the work-holding head as the head is moved away from the grinding element. A further object is to provide a shaft for supporting the grinding elementwhich is adjustable axially so as to take up wear, the bearings for the shaft being im-losed so as to exclude grit or the like. A still'turther object is to provide means for moving the work-holding head into inoperative position and simultaneously cutting otl' the supply of water to the grinding element. Further objects will appear from the detailed description.

In the drawings:

Figure 1 is a front view of the machine;

Fig. 2 is a top plan view;

Fig. 3 is a central vertical longitudinal section through the work-holding head and.

the adj aeent parts of the machine;

Fig. 4 is a similar view of the grinding head;

Fig. 5 is a detailed central vertlcal section through the grinding stone and the holding head therefor;

Fig. 6, is a sectional detail view of the Specification of Letters IPatent.

bearing sleeve 8.

Patented July 17, 1917.

Serial No. 147,417.

rollers for supporting the work-holding head supporting rods;

Fig. 7 is a detailed plan view of the multiple-armed sleeve for connecting the water control valve and the work-holding head lever and the operating lever;

Fig. 8 is a detail of one of the foot levers;

Fig. 9 is a detail of the means for holding the work-holding head supporting rod in retracted position;-

Fig. 10 is a detail of the water main and the main supply control valve;

Fig. 11 is a detail of the means for adj usting the spring containing sleeves longitudinally; and

Fig, 12 is a detail of the gripping means for the work-holding head.

Broadly stated, my machine comprises a bed, a grinding head mounted thereon, a work-holding head mounted in axial alinement with the grinding head and movable toward and away from the same, and means -cured to the bed 1 by the bolts 5 passed through the flange and threaded into the bed. The uprights 3 at the outer end of the base 2 support an integral semi-cylindrical ournal member (3. A semi-cylindrical-journal cap 7 is secured to the journal member 6, these two members cooperating to form a cylindrical journal in which is mounted a This sleeve is provided at one end with an integral annular flange 9 which engages the outer end of the journal sleeve and, at the other end, with a flange 10 which engages .the other end of the journal sleeve. vent movement of the bearing sleeve longi' tudinally through the journal. The-bearing sleeve 8 is further provided, at its outer end, with an integral inwardly extending annular flange or shoulder 11. ring 12 is rotatably mounted in the sleeve 8 adjacent the inner face of flange 11, and a similar ring l3-is mounted concentric with These two fianges.pre-

A bearing an annular groove, vand the ring 13 is provided in its outer face with a similar groove, these two grooves cooperating to form a race-way for the bearing balls 14. Two rings 15 and 16 are mounted near the other end of the bearing sleeve 8 and are grooved to form a race-Way for the bearing balls 17 The .rings 13 and 16 are mounted about a tubular shaft 18 which extends througlrthe bearing sleeve 8 and serve to provide a ball bearing mounting for this shaft so as to facilitate easy rotation of the same. A spacing sleeve 19 is mounted about the shaft between the rings 13 and 16 and serves to hold these members in proper spaced relation. The inner end of bearing sleeve 8 is provided with an enlarged chamber 20. This provides an inner annular shoulder a short distance from the inner end of the sleeve on which is seated a bearing collar 21. This collar is mounted about a ring-22 mounted on the shaft 18 with its outer end bearing against the inner face of the bearing ring 16 and its inner end in engagement with the annular shoulder formed by the end of the annular enlargement 23 of the shaft. A second collar 21 similar to collar 21 is mounted about the ring 22 adjacent the inner end thereof, and the inner face of each of these two rings is provided with a concentric groove, these two grooves cooperating to form a racc-way for the boaring balls I This provides a ball bearing which takes the end thrust of the shaft toward'ihc bearing sleeve A suitable pulley 26 is secured at the center of shaft 18 on the annular enlargement 23 thereof. This pulley is adapted to be connected by a belt to a suitable source of power so as to cause rotation of the shaft.

The two standards 3. at the inner end of the base 2 support, a scmi-cylimlrical journal member 27 similar to member (3. A journal cap 28 is secured on the member 27, these two members cooperating to form a cylindrical journal sleeve. A hearing leeve. 29 similar to sleeve 8 is mounted in this journal. This bearing sleeve is provided at call: cud with ball bearings 30 which rotatably sup o t th shaft 18 and are held in spaced relation by a spacing sleeve 31. The sn'cvc all is provided. at its outer end, with an culargcd annular chamber 32 in which is mountcd the bearing collars Ill) and ill the inncr faces of uhich are grooved to rcccivc the bearing balls 35. This provides a ball hearing which receives the end thrust of llic shall in the other direction.

The inner cud portion of the bearing slccvc, il which projects through the journal menibcr composed of the chpncnts :27 and 2 is cxtcriorly threaded to rc civc an intcl'ivu'h lhr'raulcd collar Il i lhrcadcd thcrcon. This collar 'is providcd. in its periphery, with a plurality of equally spaced inwardly extending radially disposed slots 3 1. These slots are adapted to receive the vertical arm. of a rectangular locking member 37 secured on the top of the bearing sleeve adjacent one end thereof. By this means the collar is securely locked against rotation. The inner portion of the annular shoulder 29 at the inner end of sleeve 29 is exteriorly threaded to receive a similar collar 38 which is locked in adjustment by a locking clamp 39 secured to the top of the journal member adjacent the outer end thereof. By adjusting these

collars

36 and 38 the bearing sleeve 29 may be moved through the journal member composed of the elements 27 and 28 in either direction, thus rendering it possible to adjust the shaft 18 axially so as to take up wear in the hearings or of the grinding stone.

A short collar 40 is mounted about the shaft 18 within the flange 11 of the bearing sleeve 8. A similar sleeve 41 is mounted about the shaft within the flange 29 of the bearing sleeve 29. The end portion of shaft 18 adjacent the collar 40 is exteriorly threaded to receive the jam nuts 42 threaded thereon. The other end portion of the shaft is similarly threaded to receive the jam nuts 43. The nuts 42 and 43 and collars -10 and 41 cooperate to normally prevent axial movement of the shaft, and may be quickly and easily adjusted to permit this movement of the shaft for axial adjustment by means of the

collars

36 and 38. The bearing sleeve 8 is normally secured against rotary movement by means of a key 44 passed through a key-way in the sleeve and in the lower hearing (5, -and the bearing sleeve 29 is similarly secured against rotary movement by a key 45. The. bearing sleeve 8 and the upper member 7 of the outer journal 2 are provided with alined bores 40 and 4-7, respectively, which provide an inlet for injecting oil into the bearings, the oil being placed in the sleeve 8 so that the. bearings operate in an oil bath. The inner journal sleeve and hearing sleeve are provided with similar opcnlugs for oiling purposes.

The inner end portion of shaft 18 is reduced and extcriorly threaded as at 48. A cylindrical hood 4!) is provided with an integral neck 50, aml an intermediate inner annular shoulder 51. The neck lits about the jam nuts 43 aml engages the inner end of the bearing sleeve 29. The interiorly lhriaded neck 52 of a recessed cylindrical holdinghead 53 is threaded onto the reduced portion 48 of the shaft 18, and the annular shoulder 51 of the hood 4) rests snugly about the periphery of this neck, the shouldcr 51 being provided with an inner aunularclmnncl in which is placed a suitable fabric such as fclt 53 which is saturated with a suitable. lubricant so as to rcducc l'riction. The. intogral annular llange 54 of thc head 53 is cxteriorly threaded to receive a securing collar 55 threaded thereon. This collar is provided, at its outer edge, with an integral inwardly extending flange 56 which extends inward beyond the inner face of the flange of the head. This flange 56 engages the outer face of a wedge ring 57 mounted in the head 53 and having its inner face beveled to engage the peripheral surface of a frustoconical grinding element or stone 58 mounted in the head. By this means the stone is firmly secured in the head and may be quickly and easily released therefrom. The

collar 55 is exteriorly threaded to receive a securing angle ring 59 threaded on to. the same and engaging the inner face of head 53. This ring acts as a locking element to prevent movement of the collar .54. The hood 49 is provided with a circular opening 49 in front of, and concentric with, the stone 58, so asto permit the work to be moved toward and away from the stone.

The grinding stone 58 is provided with an axial bore 58 and a conical inlet 58 communicating therewith and in register with the bore 60 extending through the shaft 18. By this means, Water which is supplied to the outer end of the shaft, by means tobe later described, is fed to the stone axially from which it flows into the article being operated upon by the stone. A nipple 61 is threaded into the hood 49 at the top thereof and is inclined downwardly and inwardly so as to direct a jet of water on to the peripheral surface of the stone, the stone and the nipple cooperating to direct water on to the stone both axially and peripherally so as to facilitate the grinding operation.

The flanged water head (52 is secured to the outer end of the bearing sleeve 8 and is provided with an interior rectangular duct (33 which communicates with the outer end of the bore 60 of shaft 18. A valve casing ($1- is threaded into the lower end of the duct 63, and is connected to a pipe 65 threaded into a boss, 66 formed integral with the bed 1. An elbow ($7 is threaded into the lower end of this boss and communicates with a horizontal pipe 68 the other end of which is connected to a pipe 69 threaded into the boss 70 formed integral with the bed adjacent the hood 49. A suit able control cock 71 is secured on the upper end of pipe 9 and communicates with a flexible tube 72 the other end of which is securedover the nipple (31. A control valve (5 t is mounted in the valve casing (34. The valve (34 and control cock 71 provide means whereby the supply of water to either the hood or the shaft may be cut oil. as desired. A T 73 is intcrposedin the pipe (38. The vertical arm of this T is connected by a nipple 74 to a valve. casing 75 which communicates by a branch pipe 76 with a main supply water pipe 77. A slide valve 78 is slidably mounted in casing 75 and is adapted to be moved into or out of operative position so as to control the supply of water from the main 77 to the horizontal pipe 68. The stem 79 of this valve extends through the casing and is connected by pin and slot connections to the upper end of a lever 80 pivotally mounted intermediate its ends on an arm 81 extending downward from the valve casing 75. The lower end of this lever is pivotally secured in the shackle 82 which is secured on one end of a connecting rod 83. By moving the rod 83 longitudinally in one direction or the other the supply of water from the main supply pipe to the grinding head may be controlled as desired.

A work-holding head 13 is mounted on the bed in axial alinement with'the shaft 18.

This head has the approximately cylindrical body 84 provided with the integral tapering neck which is releasably secured in a sleeve 86 formed integral with the supporting standard 87. The inner portion of body 84 is exteriorly threaded to receive a clamping collar 85 threaded thereon. The inner surface of this collar is beveled to engage the outer beveled faces of the clamping jaws 86*. These jaws are mounted for sliding movement in radially extending slots 87 formed at the forward end of the body 84 of the head, each jaw being provided at its inner end with integral laterally extending arms 88 which fit into grooves 89 contiguous with the grooves 87. The arms 88 and grooves 89 cooperate to prevent movement of the clamping jaws outward of the head, while permitting radial movement of these members. Each of the clamping jaws 86 is turned inward at right angles, at its forward end, to form an integral gripping finger 89. These fingers engage the outer edge of a resilient gripping ring 90 which is mounted in the clan'iping ring 85 inside of the jaws 86", being formed .of a. plurality of sections which cooperate to form a continuous cylinder. as indicated in Fig. 12 of the drawings. The various sections of the gripping head are normally held together by a sprin 91 passed about the same. By threading the clan'iping collar 85 on to the body 84, the jaws 86 will be forced inward so as to force the sections of the clamping ring 90 into tight frictional engagement with the article to be held, such as the tumbler or glass 92 shown in Fig. 3 of the drawings. A, jam-nut ring 93 is threaded on to the body 84 of the head and is adapted to move into tight frictional contact with the inner end of the clamping collar 85 so as to prevent movement of the same. liy this means the article to be operated upon may be quickly and easily secured in the holding head, and this head may be easily adjusted to accommodate articles of various sizes and shapes.

A bracket plate 94 is secured on the bed 1 by means of binding screws 95 passed through the central longitudinally extending slot 90 formed in the plate and threaded into the bed. By this means the plate is secured on the bed and may be quickly and easily adjusted longitudinally thereof. The plate 91 is provided, at each end, with a pair of spaced standards 97 on each of which is secured a cap 98. Each pair of standards supports a guide roller 99 which is provided adjacent each end with an annular groove 100. A similar roller 101 is mounted in the cap 98 with its grooves in vertical alincment with the grooves 100 of the roller 90. These two sets of rollers provide antifriction bearings for a pair of spaced rods 102 which are slidably mounted through the rollers. The standard 87 is secured to these rods by means of binding screws 87 so as to be movable therewith and adjustable longitudinally of the rods. An operating rod 103 is pivotally secured to the standard near the lower end thereof by a shackle joint 104, the other end of this rod being pivoted to the upper end of an operating lever 104 which is loosely secured on a transversely extending shaft 105 supported by integral bracket arms 100 extending from the legs 2 at one end of the table. An operating rod 1.07 is secured at one end to the lower end of lever 101 by a shackle joint 108. The upper end of this rod is secured by a shackle joint 108 to the lower end of an arm 109carried by a sleeve 110 rockably mounted on a shaft 111 carried by hangers 112 secured to the under face of bed 1. A short arm 113 extends downwardly from, the sleeve 110 in advance of arm 109 and is connected by a shackle joint 11a to the other end of the rod 83. A short arm 11!") extends from the sleeve 110 oppositely to, and spaced from the arm 113. The outer end of this arm 115 is secured by a shackle joint 116 to the upper end of an operating rod 117 the lower end of which is secured by a shackle joint 118 to a foot lever 119 which is pivotally mounted at its inner end in a supporting bracket 120 suspended from the table 1, the connection of the rod 117 to the lever being in advance of the pivotal axis of the lever. By this means, when the outer end of lever 119 is depressed, the work-holding head B will be moved away from the grinding head A, and the rod 83 is simultaneously operated so as to cut oil the supply of water to the grinding head.

The work-holding head is normally forced inward toward the grinding head by resilient means s'o as to hold the article to be operated upon in contact withthe grinding stone. For this purpose, a sleeve, or tubular casing 121 is mounted at each side of the grinding head, this sleeve being slidably supported in rings 122 formed integral with the stamiards 3. The sleeves 121 are each provided, near its outer end, with an. integral inwardly extending boss 123. This boss is centrally recessed to receive a gudgeon 12 1 carried at the inner end of the arm 125 ofa yoke 126. By this means the yoke is pivotally connected to the sleeve. The cross bar 126 of the'yoke is provided with a central aperture adapted to be brought into register with any one of a series of recesses 127 formed in an integral enlargement 128 of the bed 1. By inserting an adjusting pin 129 through the cross bar of the yoke into any one of the recesses 127, the sleeves 121 may be secured in longitudinal adjustment.

The sleeves 21 are mounted in axial alincment with the rods 102 which are slidable through the sleeves. Each rod is provided with a collar 130 which is adjustably secured on the rod by a set screw 131. The collar 130 is of such size as to be slidable through the sleeve 121, and an expansion coil spring 132 is mounted about the rod 102 within the sleeve 121 and confined between collar 130 and the inwardly projecting flange 121-formed at the inner end of sleeve 121. The coil spring 132 acts to force the workholding head toward thegrinding head so as to hold the tumbler 92 carried thereby in contact with the grinding stone 58 which is of such diameter as to tit into the end portion of the tumbler. The springs 132, due to their resiliency, permit a certain amount of give of the tumbler away from the grinding stone thus preventing binding of the stone in the tumbler. The streams of water which are directed on to the stone and into the tumbler serve to efi'ectually prevent burning of the tumbler and facilitate the grinding operation. By adjusting the collars 130 on the rods 102, and adjusting the sleeves 121 longitudinally, the amount of pressure exerted by the springs 132 on the rods may be varied so as to vary the pressure with which the article being ground is held in contact with the grinding stone. This renders it possible to efl'ect a comparatively wide range of adjustment of operative pre sure, and a very delicate adjustment of the pressure exerted on the article being ground may be obtained thus rendering it possible to use the machine for a great variety of articles of different types and textures.

To prevent injury to the grinding stone from the supporting or work-holding head in'the event of breakage of an article held by the chuck, I provide means for positively limiting the inward movement of the rods 102. For this purpose a pair of plates 13;; are securely clamped about the rods ill-LI so as to be held in tight il'ictional ngagement therewith. These plates are adapted to engage theouter standards J7 so as to positively limit the inward movennmt of the rods 102. By this means the movement of the \vorkdiolding head toward the grinding stone may be positively limited so as to prevent contact of the head with the stone in the event of the tumbler, or other article carried by the head, being broken. This plate may be quickly and easily adjusted longitudinally of the rods so as to vary the amount of inward movement or the rods to suit the particular work being ground. A push bar 134 is mounted in a sleeve 135 provided with a cap plate 136 secured ,to the body of the sleeve by bolts or machine screws. This head or sleeve is supported by arms 137 secured to the outer standards 97, and is in axial alignment with the work-holding head B. The bar 134 is in alignment with a central bore 134 extending through the neck 85 of the body 84 of the work-holding head.

When the work-holding head is moved outward away from the grinding stone the bar 134 engages the inner end of the tumbler 92, or other article, so as to force the same outward through the holding ring 90. Bythis means, when the Work-holding head is moved into inoperative position, the supply of water to the grinding head is out off simultaneously therewith andthe Work is forced outward from the holding head so as to be quickly and easily removed therefrom. To permit this outward movement of the article the holding ring 90 is flared outward slightly as.

in Fig. 3 of the drawings, the adjustment of the clamping ring 85 being such as to normally prevent rotary movement of the tumbler but permit it to be moved outward when engaged by the push bar 134. The push bar may be adjusted longitudinally to suit articles of different sizes, and the bracket plate 94 may be also adjusted longitudinally, thus permitting a wide range of adjustment so as to vary the effective length of the push bar to suit the particular article being ground.

The hood 49 incloses the head for holding the grinding stone 58 thus insuring that all water which is thrown from the grinding stone by centrifugal force will be retained within the hood. This water flows downward through the tubular standard 138 car,- ried by the hood 49 and communicating with the interior thereof. This standard is provided with an opening 138 through one side which permits the water and the particles of glass and abrasive material mixed therewith to flow outward on to the upper surface-of the bed 1. The bed 1 is provided with an internal, upwardly extending peripheral flange 139 and, at its approximate center, with a drain opening 140 which com-' municates with a suitable drain pipe 141.

By this means the water is draind off the table continuously and all splashing or throwing o-f-the water is eliminated.

The main water supply pipe 77 is pro-I rotating this hand wheel the supply of water to the various grinding heads may be cut off, or regulated, as desired.-

In actual practice I provide each table with a plurality of grinding heads and workholding heads, these members being mount ed in step order, as in Fig. 2 of the drawings. In this figure I have provided four grinding heads and four opposed work-holding heads, independent means being provided for operating each of the heads and for cutting off the supply of Water to each of the grinding heads. In this figure of the drawingsthe lower unit C of the machine is shown with the work-holding head being moved into operative position. The next unit I) is shown with the work-holding head in operative position with the tumbler in contact with the grinding stone. In unit E the work-holding head is being moved outward into inoperative position, and in unit F the work-holding head is in inoperative position with the tumbler 92 forced outward by the push bar 134 in position to be quickly and easily removed from the securing ring. By arranging the units in step order as shown, work may be quickly and easily inserted into, or removed from, any one of the units without affecting the work in the other units. The water is supplied to each of the grinding heads of the machine by means of the branch pipes 76 which are connected to the main 77. By means of the valve 142 the supply of water of all of the grinding heads may be shut offsimultaneously, or the supply of water to the heads may be controlled independently, in the manner previously described.

It will be evident that there may be slight changes made in the details of the construction and arrangement of the different parts of my invention without departing from the field and scope of the same, and I intend to include all such changes, as fall within the scope of the appended claims, in this application in which a preferred form only of my invention is disclosed.

What I claim is:

1. In a grinding machine, the combination of a rotatable shaft, a grinding element carried thereby, means for supplying water to said grinding element axially and peripherally, a work-holding head movable toward and away from the grinding element, means for normally forcing said headtoward the grinding element, means connected to the head for moving the same away from said grinding elements and means for cutting off the supply of Water to the grinding element simultaneously with the movement of the holding head away from the said element.

2. In a grinding machine, the combination of a rotatable tubular shaft, a grinding stone secured to the shaft at one end thereof and P y P p provided with a centralbore in register with the bore of the shaft, a work-holding head movable toward and away from the grinding stone, resilient means for normally forcing the head toward the stone, means for supplying water to the interior of the shaft at the other end thereof, a valve for controlling the supply of water to the shaft, a foot lever, connections between said lever and the head for moving said head away from the grinding stone into inoperative position when the lever is depressed, and connections between the foot lever and the valve for out ting off the supply of water to the shaft simultaneously with the moving of the holding head into inoperative position.

3. In a grinding machine, the combination of a rotatably mounted tubular shaft, a grinding stone secured on the shaft at one end thereof, a hood mounted about the stone, at work-holding head movable toward and away from the stone, a nipple carried by the hood and positioned to direct a stream of water on to the stone, a main water supa branch pipe connected to said main and to the other end of said shaft and the nipple, a valve mounted in said branch pipe, adjustable resilient means for normally forcing the work-holding head toward the grindin stone, means for moving the said head away from the stone into in0pera tive position, and means for simultaneously operating the valve so as to cut off the supply of water to the said nipple and shaft.

4. In a grinding machine, the combination of a rotatable tubular shaft, a grinding stone secured on one end of the shaft and provided with a central bore in register with the bore of the shaft, a hood mounted about said stone, a nipple carried by the hood and positioned to direct a stream of water on to the peripheral surface of the stone, spaced parallel sleeves mounted parallel with said shaft and positioned at each side thereof, rods slidable in said sleeves, a work-holding head carried by said rods in axial alinement with said shaft, fixed standards for supporting the rods, means mounted about the rods and in engagement with said sleeves for normally holding the rods in retracted position within the sleeves, means secured to the work-holding head for moving the same away from the grinding stone into inoperative position, a main water supply pipe, a branch pine connected thereto and to the other end of said shaft and to the nipple, and means for cutting off communication between the said main and branch ipes simultaneously with the moving of the work-holding head into inoperative position.

In a grindingmachine, the combination of a rotatable shaft, a grinding stone secured on one end of the shaft, means for supplying water to the stone axially, a work holding head movable toward and away [from said stone, means for normally forcing the head toward the stone, and 1neans for moving the head away from the stone andsimultaneously shutting off the water sup-- ply. g

b. In a grlndmg machine, the combination of a rotatable shaft, a grinding stone secured on one end of said shaft, a workholding head movable toward and away from the stone means for positively limiting the movement of said head toward the stone, and means for moving the head away from the stone into i operative position.

7. In a griniiing machine, the combination of a rotatable shaft provided with an axially extending bore, spaced elongated sleeves parallel with said shaft, means for securing said sleeves in longitudinal adjustment, rods slidably mounted through said sleeves, expansion springs mounted within the sleeves about said rods and normally holding the rods in retracted position within the sleeves a work-holding head carried by the rods in axial alinement with said shaft, means for supplying water to saidlars and the inner ends of the sleeves for normally holding the said rods in retracted position within the sleeves, a work-holding head carried by said rods in axial alinement with the said shaft, and means for moving the said head away from the shaft into inoperative position.

9. In a grinding machine, a worleholding head comprising a body portion, a plurality of gripping members carried by the body portion and movable radially of the same, and means carried by the said body and engaging with said gripping members for forcing said members toward each other.

10. In a grinding machine, a work-holding head comprising a body having an axially extending bore, a plurality of gripping members slidably mounted in the body for radial movement, a collar threaded on to the body' and adapted to engage said gripping members so as to force the same inward, and a resilient gripping ring mounted in the said body inside of the said gripping members and normally in engagement with the inner faces thereof.

away from the" 11. In a grinding machine, stone securing means comprising a cylindrical recessed head provided with an integral neck adapt ed to receive the end of a shaft, a Wedge ring mounted in the head and having its inner peripheral face beveled inwardly, and means carried by the head and engaging with said ring for forcing the ring; into the head.

12. In a grinding machine, stone securing means comprising a cylindrical recessed head provided With an integral neck adapted to he'secured on the end portion of a shaft, a Wedge ring mountedwithin the head and having'its inner peripheral face bev- 5 eled inwardly, and a flanged ring threaded on to the head and engaging the outer face TOM n. JARVIS.

to force the ring Witnesses:

W. J. ZIHLMANN, Jon H; CHARLES.