US2191930A - Work feeding mechanism - Google Patents

Description

Feb. 27, 1940. M. H. ARMs Er Al.

WORK FEEDING MECHANISM Filed Jan. 28, 1958 5 Sheets-Sheet 1 M 5,1, www5@ m W w j.

Ilr VIIMw, Vf w @C Fveb.` 27, 1940. M. H. ARMs E'r AL WO'RK FEEDING MECHANISM 5 Sheets-Sheet 2 Filed Jan. 28, 1938 IIIIAIIIJN Feb. 27, 1940.r yM H, ARMS ET AL 2,191,930

WORK FEEDING MECHANISM Filed Jan. 28, 193B 5 Sheets-Sheet 5 Feb. 27, 1940. M. H. ARMS ET AL WORK FEEDING MECHANISM Filed Jan. 28, 1958 5 Sheets-Sheet 4 NS IMJ l l n llfM -IILVII Feb- 27, 1940- M. H. ARMs E1- AL WORK FEEDING MECHANISM Filed Jan. 28, 193B 5 Sheets-Sheet 5 f Q @Q N Sw Q E Q Mw LJ@ Q QS www s m f 1,1 4 NN M W N Q Q NQ .MJ f, MMMW, @m2 ,w

`Patented Feb. 27, 1940 UNITED STATES PATENT 'l OFFICE WORK FEEDING MEcHANisM Application January 28, 1938, Serial No. 187,462

24 Claims.

This invention relates. to the feeding of work to be operated upon and more particularly to the feeding of individual work pieces, and has for an object to provide means for the feeding of such pieces through a hollow spindle and into achuck adapted to, grip the work pieces as they are fed intov it land to` release them after the desired work has been done thereon.

The invention fur-ther relates to a chuck construction especially designed for cooperation with the work feeding means.

For a ymore complete understanding of this invention, reference may be had -to `the accompanying ydrawings in which Figure 1 is a fragmentary View partly in side elevation `and partly in section of an internal grindingy machine illustrating one embodiment of this invention.

Figure 2 is a left end elevation of a portion of the mechanism shown in Figure l.

Figures 3 and 4 is a section to a larger scale on line 3 3 of Figure 2, Figure 4 showing the chuck.

Figure 5 is a section to a larger scale on line 5--5 of Figure 1.

Figure 6 is a section on line 6--6 of Figure 3.

Figure 7 is a perspective View of the Work-engaging portion of the feed mechanism.

Figure 8 is a fragmentary perspective View of the stock tube.

Figure 9 is a front elevation of the chuck.`

Figure. 10 is a view similar to Figure 4, but showing a modified construction.

Figure 11 is a front end elevation of the mechanism shown in Figure 10.`

Figure 12 is a view similar to Figure 3, but showing the modified construction of Figures 10 and 11.

Figure 13 is a fragmentary side elevation of an internal grinder provided with the work feeding mechanism of Figures 10 to 12.

Figure 14 is a detail section on line I4I4 of Figure 13.

Figure 15 is a view similar to Figure 4, but illustrating a modified construction and showing the chuck closed.

Figure 16 is a view similar to showing the chuck open'.

Figure 17 is a section on line ure 15.

50 Figure 18 is a fragmentary perspective view of the feed bars used in the construction of Figures 15 to 17, inclusive.

Referring Ifirst to the construction shown in Figures 1 vto 9,inc1usive, at I is indicated a hollow 55 work spindle, which is journaled in bearings at 2 sie Figure 15, .but

`11-11 of Figin a portion 3 of the machine. The spindle may be rotated by any suitable means, as, for example, by .a belt 4 passing about a pulley 5 keyed to the spindle, and, as shown,provided with a brakel drum extension 6 for receiving a brake shoe I by *5; whichv the rotation of the spindle may be stopped quickly when desired. The spindle I carries at one end a chuck I0. This chuck has a tapered internal face Il with which cooperate jaws lI2 having work-engaging blocks I3. These jawsI2 are carried at the outer ends of spring fingers I4 projecting from the forward end of a sleeve ,I5 axially slidable within the spindle I so that as the sleeve I5 is moved to the left, as viewed in Figure 4, the clamping blocks I3 are brought toward the axis of the spindle, thus to firmly clamp the work. By moving the sleeve to the right the blocks I3 spring outwardly and release the work. The sleeve I5 has attached to its free end shoes, such as IGa, which are positioned to guide the Work in between the clamping jaws I 3 so that work pieces may be fed into the chuck from within the hollow spindle. o

The Work consists of individual pieces as W, which are slidable within a tube 20, which,l,vas shown best in Figure 8, may comprise a pair of y inner and outer sleeves 2| and 23. v`The inner sleeve 2l is slotted, as at 24 (see Figure 8) and within these slots ride feedbars 25 which are shown detached in Figure 7. Each of these bars is provided with a series of spring stock-engaging fingers 2B which are secured to the bars at intervals, with free ends, as 21, projecting inwardly toward the axis of the spindle and positioned to engage between successive spaced apart work pieces W within the inner sleeve 2|, as shown in Figure 3. The outer sleeve 23 is continuous and holds the bars 25 from outward movement; At their rear ends the bars 25 are secured to aftub-u'- lar Iactuating part 28 which has a closed end 29in which is secured, as by a nut 30, the'forward end of a work feeding plunger 3i. This plunger extends into a fluid pressure cylinder 32 where there is xed thereto a piston 33 slidable within the cylinder. The member 28 is provided with a forward extending portion of reduced diameter, as at 34, which may engage the rear end of the last work piece W within the tube120. `It willr be noted that the member 28 with the feed bars 25 is slidable Within the inner sleeve 2|. 1 y

The heads 40 and 4I for the cylinder 37,2r are provided with fluid pressure ports 42 and 43, respectively, with which communicate fluid pressure pipes 44 and 45 by which fiuid under pressure may be admitted .or exhausted to cause reciprocation of the piston 33 and the work feeding fingers 25 to feed the work pieces forwardly within the tube 2U on each inward movement, these work pieces being spaced apart as shown. The inner sleeve 2| is shown as provided with spring fingers 4E having free ends 41 projecting inwardly, yet yieldable to permit the stock pieces W -to be fed therepast toward the chuck, and springing back behind each work piece as it passes by and preventing return movement of the Work pieces during the retraction of the feed bars 25.

The heads 4Iland 4I of the cylinder 32 are secured together and to a stationary member 5I! within which the rear end of the tube 2l) extends, as by bolts 5I, and this member 50, as shown best in Figure 5, is provided with a pair of flanges 53 to which may be secured a flange 54 of a work-holding upwardly inclined chute 55. The work pieces, which are shown as ring members, may be fed into the upper end of the chute 55 from which they may fall through a slot into the rear end portion of the tube 2!) into the position shown in Figure 3 .directly in front of the feeding member 28 by which they may be fed forward into the tube 2i). As shown herein, the tube 2G is non-rotatable, being secured to the member 59, its forward end extending into the spindle I and opening adjacent to the back of the chuck Ill, the sleeve I5 being journaled thereon through an interposed rubber sleeve 55. Fluid under pressure is supplied and exhausted with reference to the opposite ends of the cylinder 32 through the pipes 44 and 45 by means of a valve 65 (see Figure l) the stem 6I of which is provided with the heads 32 and 53 and whose outer end carries a cam roller 64 for cooperation with a cam 65 secured to a shaft 5B. The follower roll 64 is held up against its cam as by means of a spring 650 bearing against the inner end of the valve stem 6I. Fluid under pressure is supplied to the Valve through the pipe I'I and is discharged therefrom through a pipe 68. In the position shown in Figure l, fluid under pressure is admitted from the inlet pipe El past the head 63 and into the pipe 45 so as to hold the piston 33 in its retracted position, but when the high spot 69 of the cam 65 contacts with the follower roll 64, the valve stem is moved to its opposite position where fluid under pressure is'supplied to the pipe 44 and discharged from the pipe 45, thus causing the piston with the feed fingers to be moved in feeding direction.

It will, of course, be necessary that the chuck be open when the feed action takes place in order that the work piece next adjacent tothe chuck may be fed thereinto. This is accomplished, as shown, by the axial motion of a spool I normally spring pressed to its left hand position by the coil spring 7| bearing against its right hand end and against the adjacent end of the spindle I. 'Ihis spool 'ID is secured as by its ange 'I2 threaded thereon to the rear end of the-chuck sleeve I5, and while it rotates with the spindle, it may be moved axially by means of a fork 'I5 having shoes Iwhich may be engaged back of the spool flange TI. Rocking of the fork 'I5 in clockwise direction, asviewed in Figure l, causes the sleeve I to be pushed forwardly, thus releasing the clamping jaws I3 and permitting the stock piece next to the chuck to be pushed thereinto, this, in turn shoving out at the forward end the piece previously in position within the chuck.

The work piece, which is moved into the chuck, passes by stop member 80, one of which is shown in Figure 4. Each member 80 ispivoted, asat 8l, to the chuck member ID and is normally spring pressed by the spring 82 into position f with its inner rear end engaging with the chuck body at a and back of the rear face of the work piece W Within the chuck, but it may be depressed by the engagement of the work piece W on its rearward inclined face 83 so as to permit the work piece to pass freely therepast. As soon as the work piece passes beyond it, it is pushed into stopping position by its spring' 82. On the subsequent rearward motion of the sleeve I5 to close the chuck the work which has just-been fed thereinto is clamped in position by the jaws I2 carrying the blocks I3 after it has been pushedv back against the stops 8U by spring fingers 86 on the clamping jaws 85. These jaws 35 are fulcrumed as at 81 on `the forward end of the sleeve I5 and are normally urged `outwardly as 4by springs B8 reacting between them and lthe end portion of the sleeve .I5. with inclined faces 39 cooperating with inclined faces 90 on the chuck I0 so that` as `the 'sleeve l I5 is drawn backwardlyfto close the chuck, the fingers 85 are closed. The extent ofthe pressure of the spring fingers 86 against the forward face :alsl

of the work piece may be adjusted as by means i of the screws SI which extend throughholes in the spring ngers Stand are threaded intothe members 85. When the chuck opens, these ngers 86 are removed from their normal positions in which they would prevent the discharge of work from4 the chuck. r f

The actuation of the fork I5 to yfree thework or to permit the spring II t0 clamp'the work is produced by a cam 95, alsoA carriedbythe' shaft 65 and which is provided with a hump 97. When this hump engages the cam follower roll 98 journaled on the arm 99 of thev fork "I5, this fork'is swung about its pivot III() in a; direction i to release the chuck, whereuponthe shift` of the valve stem 6I is keffected to accomplish the feed of the stock. I

In Figure 1 the grinding wheel IUE for operat ing on the work pieces which are successively' presented into the chuck is illustrated, this grinding wheel being driven by any suitable means (not shown).

Another feature of the present invention is the introduction of coolant to the work piece as it f is being operated upon, through the hollow spindle. For this purpose the sleeve 2l is shown as provided with longitudinal grooves I II) in its out- Y er face which lead to ports III (see Figure 4) passing therethrough adjacent to the forward end of the sleeve. These grooves IIIB'are closed off on their outer faces by the sleeve 23 so that coolant passages are formed through the tube 2l] comprising the sleeves 2l and 23 andthe sleeve 23 is provided with holes II2 therethrough coinmunicating with the rearV end portions ofthe grooves III) as shown in Figures Sand 6. The member is also provided with an annular internal groove H3 with whichv the openings H2` register, this passage II3 being extendedon one..

side to form the bore of an inlet pipe I I4 through which coolant may be introduced, as through the supply pipe H5 shown in Figure 1. Y

In Figures l0 to 14 a modiflcationis shown n which the Work pieces are fed to the chuck in 'contacting relationship with each other, instead of in spaced relationship as in the construction. previously described. In this modification the work pieces W are fed through lthe sleeve I30, which is provided with longitudinal external They are provided v,in the mechanism previouslydescribed, vhaving the chute |31 through which stock may be supplied through a slot |38 4(see FigurelZ) into alinement with the work pieces within the sleeve |30.

Within this member |35` they are contacted by the feeding plunger |40 actuated by the piston|4| y inthe uid pressure cylinder |42.

by lthreading to the sleeve |30. This spool |80 The feed bars |3| havesecuredthereto at their foi-ward ends-resilient feed fingers '|45 (see Figure which extendthrough slots |43 of the sleeve or. tube |30 and engage only the last work piece back ofthe chuck |48. This chuck |48 is somewhat similar to the chuck I0 ypreviously described. It is provided with guide fingers y|50 between which `the work piece maybe guided and supported while in the chuck, and the work pieces` are fed into the chuck successively past the stop dogs |52. Each stop dog is pivoted as at |53 and is spring pressed against a stop |54 as vicy-means of a `spring |55.v `When resting against the' stop |54 a portion |56 of each dog extends in between the work piece in the chuck,H

and the next work piece to be fed thereinto. In this position, also, clamping dogs such as |60 pivoted at |8| have their inner ends at |62 -pressed against the. forward face of the work piece thenin the chuck as by engagement of the blocks |64 against portions |65 of these clamp dogs.y These clamp dogs are secured to the extensions |66 ofthe sleeve |30 and this sleeve is `arranged to bev pulled rearwardly to bring the dogsv |60 down into locking position and to pull them back against the forward face of the work piece. On inward motionof the sleeve |30, the

portion |65 of each -o-f the locking dogs may ridefoutwardly. acrossan inclined face |61 of lthe block |54, thus permitting these dogs to release the Work under the action of their releasing vsprings |158...l The sleeve |30 may be reciprocated 'tothus clamp cr release lthe work..

and close the chuck by motion of a spool |80 having its rear ange member `|8| secured as 'is Y. normally held retracted to hold the work clamped by the chuck and held back against the dogs |56bymeans of a spring |82 (see Figures 12y and 13) and it is moved inwardly to release the work from the chuck so that a succeeding workl piece may be fed thereinto and the work piece in position dischargedfrom the chuck by the feeding motion of the feed bars |31. This is done by the .rocking of a fork |83 having shoes |84 which may be `engaged with the spool flange |85.

.This fork |83 is fulcrumed at |86 and its arm |81 carries a camlfollower roll |88 which rides on the edge cam |89. The two cams and |89 are carried bythe shaftV |90 whichcarries a third edge cam |81 Awhich actuates the valve plunger 6| of the valve 60, 'as heretofore described, to produce the fluid pressure feeding action f the work pieces within the sleeve or tube |30. Thus, after the chuck has lbeen opened the feed fingers |45 are actuated to feed the last work piece in tube |30 into the chuck, dislodgingthe work piece previously therein, the dogs |56 yielding to permit the passage of the work pieces in this direction. This feeding motion of `the fingers |45' eff ects only the last Work piece in the sleeve |30 and spaces it from the next work piece sufficient to permit Vthe dogs |56 to spring in between. Thereafter the closing movement of the `chuck clamps the work piece therein against the stop dogs |56 in the position shown in Figure 10.`

In Figures 15 to 18 is shown a further modification in which the work pieces vare fed spaced apart, as in the structure shown in Figures 1 to 9, but in this modified construction no stops such as 80 of Figure 4 are employed. The work feed bars such as 25a are each extended and provided with a spring 200 forwardly of their feed fingers 25. These springs may ride in grooves in the inner faces of the shoes |6a carried by the sleeve |5, as shown in Figure 15, when the work is in fed position, and they may be retracted to engage the next work piece as shown in Figure 16 ready for a succeeding feeding motion of the bars ct. In the latter position of the parts the sleeve I5 has been moved forwardly to permit the jaws 85 to be released from the work by the springs 88. A succeeding feed motion of the bars 25a then pushes the next piece to bernachined into the chuck, pushing out the finished piece, and then instead of retracting all the way they will be retracted only sufliciently for the springs 200 to retract the work piece in the chuck enough for the jaws 85 and the fingers 86 to swing in without the fingers striking on the periphery rather than on the outer end of the Work piece in the chuck. The work piece is then held between the jaws and the ends of the forward feed fingers 26 as shown in Figure 15, the feed fingers then acting-.as stops in place of the stops 80 of Figure 4, and preferably remaining in .stopped position and pressing the work piece forwardly by fluid 'pressure exerted on the feed piston 33 during the operations on the work piece held in the chuck. Thereafter the feed bars are retracted to the positions shown in Figure 16 preparatory to the succeeding feeding action. The cam for controlling the fluid pressure valve 60 will, of course, be modiiied in contour to produce this different cycle of motions of the feed bars.

From the foregoing description of certain embodiments o f this invention, it should be evident to those skilled in the art that various further changes and modifications may be made without departing from the spirit or scope of this-invention as defined by the appended claims.

We claim: y

1. In combination, a hollow spindle, a lchuck at oneend of said spindle, means within said spindle for feeding individual work pieces through sleeve having longitudinally arranged slots therein, work-feeding bars slidable in said slots, workengaging ngers carried by saidbars for engaging work pieces within said tube, means to open and close said chuck, and means actuated in time with said opening and closing meansfor reciprocating said bars to feed work pieces through said tube into said chuck.

3. In combination, a rotary spindle, a stationary ktube within said spindle comprising a pair of concentric sleeves, a chuck carried at one end into said chuck, said sleeves also forming'between them one or more passages for coolant to be delivered to a Work piece held by said chuck.

v4. In combination, a rotary spindle, a stationary tube within said spindle comprising a sleeve, a chuck carried at one end of saidspindle, said sleeve having longitudinally arranged slots tlerein, work-feeding bars slidable in said slots, workengaging spring fingers carried by said bars for engaging work pieces within said tube for feeding said work pieces by reciprocation of said bars, means for preventing backward motion of said work pieces when said bars are retracted, means to open and close said chuck, and means actuated in time with said lopening and `closing means reciprocating said bars to feed work pieces through said tube into said chuck.

5. In combination, a rotary hollow spindle, a tube within said spindle, a chuck carried by said spindle and having work-gripping jaws, and means preventing the discharge of work from said chuck, said tube being positioned at the entrance to said chuck, means for feeding work pieces one by one within said tube toward said chuck, and means for opening said jaws and releasing said preventing means to cause the feeding of said pieces scccessively into said chuck to discharge from said chuck the piece previously fed thereinto, and for positioning said preventing means and closing said jaws to grip the work piece last fed into said chuck.

6. In combination, a rotary hollow spindle, a stationary tube within said spindle, a chuckl carried by said spindle and having work-gripping jaws, and means preventing the discharge of work from said chuck, said tube being positioned at the entrance tosaid chuck, means for feeding work pieces one by one within said tube toward said chuck, and means for opening said jaws and releasing said preventing means to cause the feeding of said pieces successively into saidchuck to discharge from said chuck the piece previously fed thereinto, and for positioning said preventing means and closing said jaws to grip the work piece last fed into said chuck.

7. In combination, a rotary hollow spindle, a stationary tube within said spindle, a chuck carried by said spindle and having work-gripping jaws, and means preventing the discharge of work from said chuck, said tube being positioned at the entrance to said chuck, means for feeding work pieces one by one within said tube toward said chuck, a sleeve between said tube and spindle movable axially for opening said jaws and releasing said preventing means to cause the feeding of such pieces successively into said chuck to cause discharge from said chuck yof the piece previously fed thereinto, and for closing said jaws and positioning said preventing means to grip the work piece last fed into said chuck, and

means for moving said sleeve and said feeding means in proper timed relation.

' 8. In combination,l a hollow spindle, a chuck on said spindle, means movable axially of said spindle for opening and' closing said chuck, uid pressure actuated means for feeding articles successively through said .spindle into and then through said chuck lwhile said chuck is open, a

valve for controlling said feeding means, a rotary 1 shaft, and means actuated by the rotationMOfr said shaft for actuating said opening and closingl means and for controlling said valve.

9. In combination, a hollow spindle, ay cluck `A carried by said spindle, a tube within said spindle ,y

and having longitudinal guide grooves therein, bars slidable in said grooves, work-engaging fingers carried. by said bars for engaginganfd moving` work pieces in said tube axiallyk thereof and into said chuck, chuck-opening and closing means, and means for actuating said opening and closing `means and saidbars in proper timed` relation. l

l0. In combinatioma hollow rotary spindla'a chuck carriedby said spindle, La stationarytube within said spindle and having longitudinalv guide grooves therein, bars slidable in said` grooves, work-engaging iingerswcarried by vsaid bars for engaging and moving work pieces in said -tube axially thereof and into said chuck, chuckopening. and closing means, and means for'actuating said opening and closing means and saidv bars in proper timed relation.

fat

il. In combination, a chuck, stop meansnor- I maliy limiting one extent of motion axiallyof said chuck of a work piece carried thereby, means to n feed work pieces successively into said chuck, means for engagement with said work piece so fed in position to hold saidk work pieceagainst pieces into said chuck therepast.

' said stop means, and means for mountil'igsaidV f f stop means to yield to permit the passage of work cessive spaced relation through said spindle and j into said chuck while said chuck is open, a stockv stop, and means for interposing said stop inthe' space between a work piece in said chuckand the next following work piece in each feeding action. l

13. In combination, a vhollow spindle, 'al chuck on said spindle, means for opening and closing cessive spaced relation through said spindle.v and said spindle after 50 said chuck, means for feeding work pieces in suc- 'l1' into said chuck while said chuck is open, a stock stop, means for interposing said stop in the space between a work piece in said chuck and the next 55 following work piece in said spindle after each feeding action, and means for clamping the Work piece against said stop.

14. In combination, a hollow spindle, a vchuck on said spindle, means for opening'and closing said chuck, means for vfeeding work pieces inl abutting'relation step by step throughsaid spindie toward said chuck, means for advancing the work piece adjacent to said chuck an amount.. ff

greater than the extent of said stepby step feed into said chuck when said chuck is open to space said piece from the ,next adjacent piece, a stop, l l and means for interposing said stop in said space after each feeding action.

l5, In combination, a hollow spindle, a chuck .y

on said spindle, means for'opening. `and closing said chuck, means for feeding work pieces in u abutting relation step by step through said spindle toward said chuck, means for advancing the work lpiece adjacent to said chuck an vamountAIV means for feeding work pieces step by step and in contact with each otherl through said tubev toward said "chuck, and means engaging each work piece on its emergence fro-m said portion and feeding it by a further amount into said chuck.

17. In combination, a hollow spindle, a chuck carried by said spindle, a tube within said spindle having one end portion positioned adjacent to said chuck, means to open and close said chuck, means for feeding work pieces step by ste-p and in contact with each other through said tuber toward said chuck, a member positioned within said spindle and .outside of said tubeand having means for engagement with a work piece on its emergence from said portion, and means acting v while said chuck is open and after each step by step feeding movementl of work' pieces within said tube to actuate said member to move the work piece projecting from said portion into said chuck.

18. In combinatiom `a chuck having workclamping jaws and stop means` for limiting the axialv motion of work backward in `said chuck, and means actuable yto feed in an individual work piece from. the back of said chuck and to hold said work piece against said. stop means.

19. In combination, a chuck `having workclamping jaws and spring stop fingers4 carried by said jaws for yengagement with the front end face of a work piece held by said chuckand means actuable to feed a work piece into said chuck from the back andto` hold it against said stop fingers.

20. In combination, a chuck havlngan internal tapered face, a plurality of' work-engaging jaws ,engaging said face and movable axially of said chuck to grip .and release the work therebetween, saidjaws having iingers positioned to engage on the forward face of a work piece carried by said jaws, and means `actuable to feed work pieces thrust. l,

successively into the back of said chuck while said jaws'are open, discharging the work piece previously in position, said feeding means presenting stop portions to a workpiece fed into said chuckagainst which said piece is pressed vby said fingers as said jaws'are moved axially of said chuck into work-gripping positions.

2l. In combination, a hollow spindle, a chuck at one endfof said spindle, means for feeding a plurality of work pieces in said spindle simultaneously toward said chuck and that one'nextback of said chuck into said chuck in spaced relation to the next following work piece in said spindle, means for opening and closing said chuck in timed relation to the .feeding of said work pieces vvand means engageable with the back face of the work piece in saidchuck for holding said work piece against backward movement.

22. In combination, a hollow spindle, a chuck at one end ofv said spindle, means for feeding a plurality of .work pieces in said spindle simultaneously toward said chuck and that one nextv back of said chuck into said chuck in spaced relation tothe next following work piece in said spindle,rmeans for opening and closing said chuck in timed relation to the feeding of said work pieces, yand a work stop moving into and out of position back of theY work piece in said chuck in said space.

23. -In combination, a hollow spindle, a chuck at one end of said spindle, means having parts engageable 'with each of such work pieces for feeding each of a plurality of work pieces spaced apart relation through said spindle and the adjacent one in said spindle into said chuck, and means for opening andclosing said chuck in timed relation to the feeding of work pieces.

24. In combination, a hollow spindle, a chuckl at one end of said spindle, means for feeding `each of a plurality of work pieces in spaced relation through said spindle and the adjacent one in said spindle into said chuck, means for Openingv and closing said chuck in timed relation to the feeding of said work pieces, and means engageable with the back face of the work piece in said chuckr for holding it `against backward y MERTON H. ARMS. JOSEPH B. JOHNSON. ALBERT TURNER.

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