US1880374A - Automatic positioning mechanism for billets and the like - Google Patents

Description

IKE

Oct. 4, 1932. F. P. DAHLsTRoM AUTOMATIC POSITIONING MECHANISM FOR BILLETS AND THE L .R N N u Fhu Q gf STQ e E R f w 4 m u 4, w A mini. Q A d m l m m @w TMR @uw N Jh 4 Y NVHWMHMUIMH .N NW WNW m, H

Oct.' 4, 1932.

F, .V DAHLsTRoM 1,880,374

AUTOMATIC POSITIONING MECHANISM FOR BILLETS AND THE LIKE Filed Aug. 4. 1930 3 Sheets-Sheet 2 'mi fig@ Oct. 4, 1932.A F. P. DAHLSTROM AUTOMATIC POSITIONING MECHALNISM FOR BILLETS AND THE LIKE s sheets-sheet 5 Filed Aug. 4, 1950 ill) iid

Patented Oct. 4, 1932 rssu FRANK IP. DAHLSTROM, F WORCESTl-llR, MASSACHUSETTS, .ASSG-NOB TO coNsTnuoTIoNr COMPANY, MASSACHUSETTS AUTOMTIC POSITION'ING MECHANSM FOR BILLETS AND THE LIKE Y Application inea August 4, 1930.` serialY 110.473,099.

The present'invention relates to the mechanical handling and positioning of elongated pieces of stock. The principles of the inven-tion can be made use ofvin a variety of ways, but they are 'particularly applicable to `the mechanical handling -and symmetrical positioning of unequal-length billets vor the like, such as are presented' successively for charging .into a furnace or other chamber.

For the charging of billets into :a furnace, one 'well known type of apparatus provides a mechanical pusher which engages the rear end .of each billet to move the same longitudinally through an opening in the furnace wall, until the entire length of the Abillet is within the furnace chamber; thereupon, the thuscharged billet and those preceding it in the furnace) is pushed broadside toward the -di'scharge end of the yfurnace to make room for the next'billet to be delivered longitudinally by the charging pusher. Ifthe strokes of the latterare of uniform amplitude, it follows that inequalities in the lengths of the billets charged thereby will produce an unsymmetrical and unbalanced arrangement-of the billets within the furnace chamber, giving rise to unequal heating eects and also to the possibility 'of disarrangement `ofthe charged material. by the action thereon of the broadside pushing devices. Moreover, these difficulties cannot be overcome by using Aa charging pusher Whose stroke is variable at the will of an operator, since the operator who would make such adjustments is'unable to observe the progress across the furnaceriloo'r ofthe front end of any billet being charged; therefore any manual adjustment of the pushers strokes would be purely a matter of guesswork. w

This invention overcomes the above-'mentioned di'iiicultiesby the provision of mecha- Y nism which, in the handlingof successive billets or other pieces of varying lengths. automatically procures the advance ofeach piece through such a distance as will bring the 'longitudinal center of every piece vto the same point in the furnace or other chamber; in this way, regardless of variations in the lengths ofthe charged pieces, a symmetrical arrangement fof the same, with respect to the center line of the receiving chamber is obtained, thereby assuring, in the case of a furnaceV chamber, uniform heating efects,and also the proper operation of the broad-side pushers against the mass of charged lpieces within the' l furnace. 'According to the inventiomeach or WORCESTER, Messacnusn'rrsn CORPORATION or operative movement of the charging pusher, Y

always fromithe same starting point, 'serves' initially to carry each piece into contact with a flag Vor trigger having 'a fixed location; the distance through which'tlie pusher moves vto effect this initial contact isa variable, bearing an inverse relation to the length of the piece;

and thereafter, Vthe amplitude of the pushers I further movement, to complete the charging and positioning operation on the piece,.is detcrminedm response' to saidV flag contact, by the amplitude of said variable initial movement so as to'reverse the pusher when its vdistance from a predetermined point (onthe center line ofthe furnace) is one-half the length of the piece being charged. I

An adaptation of the Vforegoing principles to a furnace charging mechanism, operating Fig. 5 is a sectional view on the line 5 5 Y of Fig. 4. p

Figs. 6 and 7 are wiring diagrams. illustrating the electrical rcircuits wat. Ydierent stages in the operation of the charging Vmechani sm.

8 is a diagrammatic view, by which the operation of the invention may be demonstrated.

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

l shows in sectional plan view a furnace l Ahaving a charging opening 2, through :sov

preceding it in the furnace) "a broadsidel movement of approximately the width of a billet; in this manner, the way is cleared each time for the charging ofthe next billet, and the farthest-advanced billet in the vfurnac'eis brought into line with a. discharging pusher- 4 at the other end of the furnace, which is operated to procure the endwise delivery of the successive billets through an opening 5.

The endwise charging movement of each billet, through opening 2, is effected in the present instance by a pusher head 6, suitably mounted in overhanging relation'upon a reciprocatory carrier 7, the head 6being adapted to pass through opening 2 well-into the furnace when the carrier lapproaches theV left hand limit of its movement, Fig. 1. The carrier 7 runs on suitable guides or rails 8,- 8, being moved in any suitable way as by a cable or chain 9 attached thereto and passing around the; pulleys 10, 10', the last named, as

I here shown, being the driving pulley for said cable, and for this purpose being suitably connected, as by reduction gearing 11, to the shaft of areversible electric motor 12. Other reduction gearing 13 connects said motor shaft to the shaft 14 of a control device 15, the latter being of the General construction shown in Fig. 2.

Referring to-Fig. 2, and also to Figs. 3, 4 and 5, the shaft 14 providesl oppositelythreaded portions 16 and 17, the former fitted with a nut 18 which is compelled alwaysto travel longitudinally when the shaft 14 rotates by reason of being. restrained against r0- tation, as for eXample,-by thereceptionofa .l tongue 18 thereon in an elongated slot or guideway 19.- The travelling nut 18 carries a normally-closed switch 20, contained in an electric circuit herein after to be described that controls the reversal ofl motor 1 2. i

The other oppositely threaded portion 17 of 4shaft 14 has iitted'thereto, a nut 21, normally free to rotate in unison'with said shaft when disposed adjacent to a collar or stop 22 thereon, as shown in Fig. 2. The periphery of i, nut 21 provides equally spaced ratchet teeth 23, as shown in Figs. 3 and 5, with which a pawl24, pivoted at25, is adapt-ed to cooperate,

, when the nut 21 is at the outer end of screw q portion 17 against the collar' 22 and directlv over said pawl, asshown in Fig; 2. Under these conditions, so long as thepawl remains out of engagement with teeth 23, the -nut21 will turn in unison with the shaft, in the absence of endwise movement thereon;l when the pawl 24 is rocked, so as to eneagethe teeth,

the nut 21 cannot rotate in the direction of arrow 26, Fig. 3, and if this be the direction of rotation of the shaft, said nut will start to move inwardly on the screw portion 17. Such inward movement will continue, even after the teeth 23 have left the pawl 24, because said teeth will then be in engagement with an elongated stationary projection 27 (see Fig. 5)` which holds saidY nut against rotation. If the directionof rotation of shaft 14 is that ofthe arrow 28, Fig. 3, when the 'pawl' 24 engages with teeth 23, the nut 21, when disposed against the collar 22, will turn with said shaft, because the teeth 23 can ratchet past the pawl 24.l

Y The pawl 24, as shown inFig. 3, has a link connection 29 with the plunger of a solenoid 30 ,when the' latter is energized, said pawl is prevented from engaging the teeth'23; decnergization of said solenoid, as by breakingof the electrical circuit iny which it is contained, renders said pawl operative to hold the nut 21 against rotation, `as above described. As shown in Fig. 1, apivoted flag or trigger 31 is disposed adjacent the charging opening 2 in position to be struck androcled lby the front end of each billet successively acted upon by the charging pusher 6. v In its normal position,.in the absence of billet engagement, said iag or trigger 31 engages with a stationary Contact 32, thereby to close an electrical .Cire

cuit which, as hereinafter described, contains the solenoid 30, whose energization keeps the pawl 24 out of action. At arcertain'pointin each charging movement'of pusher 6, the billet being charged strikes the trigger 31, and opens this circuit at the `contact 32, thereby deenergizing the solenoid 30and, .through pawl 2 4, inaugurating theinward travel of nut 21-along screw portion 17 this .point comes at different times, dependingupon the length of the billet being charged; with a long billet, it `comes early*l in the chargingmove ment of the pusher, and with a short billet it comes later. A A.

Referringfnowto the wiring diagram of Figs. 6 and 7 ,the motor 12, switch 20, solenoid 30 andV flag switch 31, 32 are shown in their respective circuits in connectionA with a control switch 33 and a double pole reversing switch 34, the -electrical current supply having its plus and minus sides at 35, 36, respectively. The master switch carries three'bars 37, 38 and 39 which, in the on position of said switch shown by Fig. 7, connect respectively the pairs ofspaced stationar7 contacts 40, 40, 41, 41,.and 42,42; in the olf position of saidswitch shown in Fig. 6, the bar 37 connects the pair ofspaced stationary contacts 43, 43. vThe reversing switch y34 comprises members 44 and 45, pivoted respectively at 46 and 47, and connected by a link 48 for movement iii-unison. Said movement is effected by the plunger 49 of a solenoid 50; when the latter is energized, the switch bars 44 and 45 nthis position the pairs of spaced stationary` contacts 56, 56 and 57, 57, respectively; also in this position, the member 45 connects a stationary contact 58 with the pivot 47, the

` latter having a conductor 59 running to the motor V12'. In the other position of reversing switch 34, the bar 51 connects a fixed contact 60 with pivot 46, andthe member 45 connects a Xed contact 61 with pivot 47.

Let it be assumed that the pusher 6 is in its full retracted position shown in Fig. 1, this corresponding to the maximum separation of the nuts 18 `and 21, as indicated on Fig. 2, the motor 12 being inoperative, and the shaft 14 at rest. By any suitable means, not shown, one of they billets z is deposited in the path of pusher 6, in line with opening 2, for charging into the furnace. In order to initiate-a single cycle of pusher operation, the control switch 33 is first moved into the olf positionshown by Fig. 6; this establishes a circuit for the energization of solenoid 50, the current flowing by conductor 35 to contact 52, throughv 'gthe solenoid 50, and thence by way` of bridged contacts 43, 43 to the minus side 36 of the supply. y With the solenoid 50 thus energized, the reversing switch 34 moves intothe position shown in Fig. 6, and this establishes a holding circuit for solenoid 50, in parallel with the bridged contacts 43, 43, the flow of current from said solenoid being through the bridged contacts 56, 56, and then through the closed switch on nut 18' and the closed switch 63 back to the minus side 36 of the electrical supply. Inthis position of the reversing switch, the motor 12, when its circuitr is completed, will run in the direction that produces the charging stroke of pusher 6, being the direction corresponding to rotation of shaft 14 in the direction of arrow 26, which causes the nuts 18 and 21 to approach each other. V

To inaugurate the operation of motor 12 and its control device 15, the switch 33 is shifted into the on position shown in Fig. 7 by this movement, notwithstanding the opening of contacts 43, 43, by disengagement of the bar 37, the energized condition of sole- 2 noid 50 remains undisturbed, because ofthe holding circuit established forsuch solenoid through the Ybridged contacts 56, 56, and closed switch 20. Hence, initially,the reversing switch 34 maintains the position shown in Fig. 6, notwithstanding movement of control switch 33 to the on position. 'Referring to Fig. 6, and assuming control switch 33 in its on position, two circuits are established; one of them energizes the solenoid to draw the pawl 24 away from the nut 21,

the iiow ofcurrent, in this instance.being through the bridged contacts 41,41, bridged contacts. 57, 57, closed flag switch contacts 31,

32, solenoid 30, and bridged contacts 40, to,

the minus side 36 of the electrical supply; The other circuit so established is through the. motor 12, to inaugurate the latters operation; theiow of current in this instance is by conductor 35 to contact 52, thence through bar 51, pivoty contact 46, conductor 53, .7

bridged contacts 42, 42 through the motor 12 and then byy way of conductor 59, pivot contact'47', switch member 45 and contact 58 to therminusA side 36 ofthe supply line.

As'the carrier 7 vstarts to travel inwardly from its full-retracted.position, Fig. 1, a proj ection 7 Y thereon moves into closed position a switch62 (Figs.`6 and 7): which connects the open contact 61 withtheplus side 35 of the electrical supply.. The inward movement of carrier 7 isv accompanied by rot-ation of shaft 14 in the direction: of arrow 26, and this produces inward movement of nut 18, but not of nut 21, the latter having been released by pawl 24, so that it rotates initially in unison with shaft 14. However, when the `billet t", under the influence of inwardly moving pusher 6, contacts at its front end with the trigger 31, the latter is moved away from contact 32, thereby vopening the circuit of the solenoid 30; thereupon, by the deenergiza-A tion of said solenoid, the pawl 24 becomes operative to?. hold the nut 21'against rotation, whereby inward movement of'said nut along the threaded portion 17 of 'shaft V14 is inaugurated. From this point on, in the charging stroke of pusher 6, both nuts-18 and 21 participatein the approach toward each other; finally, at some point (the location of which depends upon how soon the nut 21 may have started its inward movement) ,the nut 21 con-l tacts with the movable member'20 of switch 2() on nut 18, thereby opening said switch, and breaking the circuit of the solenoid 50.

Thereupon, by the deenergization ofsole v noid 50, the reversingswitch 34 shifts into the position shown by Fig.v 7, procuring reversal of the direction of current through motor 12, the flow ofcur'rent now being from conductor`35 through closed switch 62 to coni' tact 61, thence by switch member' 45, pivot contact 47 and conductor 59 to the motor, with Y return to the minus side 36 of theelectrical supply through vcontacts 42, 42, bar 39, conductor 53 and contacts 46 and'60. In this way, by reversal of motor 12, the inward stroke of pusher 6 is terminated and its outward or return strokeis begun,-the shaft l14 alsobeing reversed, so that the nuts 18 and'21 begin to recede from each other. Although this recession permits the switch 20 vto closev (under the action, fOr'eXample, of a spring 20"), there is no ensuing reenergization of solenoid 50 to shift the reversing switch 34, since the holding circuit of said Vsolenoid 50 has been opened atthe contacts 56, 56 by the aforesaid reversal of switch 34. Also,notwithstanding the return of switch 31, 32 to closed Aposition (in consequence of billet t moving completely lpast the same), there is no effect on the solenoid 30, sincethe reversal` of switch 34 has brokenlthe circuit of said solenoid at the contacts 57,57, while the nut 21. is being held against rotation by .projection 27; hence towardtheend of the return 7 strikes'thesw'itch 62to open the same,

thereby breaking the circuit of motor 12 and causing stoppage ofthe mechanism 'at the completion of a single cycle of .operations thereof. ln order to repeat the cycle, for the charging of the next presentedV billet '15,- the control switch 33 must firstbe moved into itsfoff position (Fig. 6) to energize the solenoid and thereby restore the reversing switch 34 to the position shown in-rFig. 6; thereafter, the controlswitch 33is shifted to the on position (Fig. 7) tostart the motor 12.

, The diagram of Fim'8, taken in'connection with Fig. 1, establishes the capacity-of the above described mechanism to centralize different-length billets in the furnace 1, so'that invariably each billet is brought to` rest in the furnace with its longitudinal center on the center line -ZJ of said furnace. Assume L as the length of the longest billet receivable in the furnace, c vas the distance the retracted pusher 6 musttravel before billet L strikes the switch 3 1, 32, and a as the distance from switch 31, 32-to the stopping point of pusher 6 when the latter centers billet Lin the furnace. Thus the total pusher movement,in the case of billet L, is c +Lla,'-0 representing the initial independent travel of nut 18, and L-l-arepresenting the joint travel of the two nuts 18 and 21. On Fig. 8, line lw-fw represents the full retracted position of Ypusher 6, and also the corresponding position of nut 18; line 2 2 represents the outermost position of nut 21; line afm representsfor billetL the travel of pusher 6 through distance c to open switch 31, 32, said distance c measuring theindepenednt travel of nut 18; and line g/-y, midway between e-.e and 'ca -m, represents the meeting point of the nuts 18 and 21, to open switch 20,+the travel' of each nut in this case being measured by the distance L-l-a.

For a shorter billet Z, the travel of pusher 6 required to effectopening of switch l31, 32,

is-o-l- (L -Z 5 on Fig. 8, this distance is repre- Z+ a -im. i

N ow the total travel of the two nuts 18 andl sented as requiring initial pusher movement from line .'w-fw to linen-m', and this disq tance, c-l- (ZI-Z), is a measure ofthe inde pendent movement of nut 18 when the shorter billet Z is being charged. The line yl-Jy', midway between e-z and :1f-', represents the meeting point of the two nuts 18 and-21 Vin their joint movements, to complete the charging of the shorter billet Z.

i Now the pusher 6, after moving a distance 0+ (L ,Z) to engage the short billet Z with switch 31, 32, wouldthereafter move the d istance Z-la to travel to the point of its reversal for the long billet L. But as shown in Fig. 8, the pusher goes farther always for the short billet than for the long billet, the excess of travelbeing represented in Fig. 8 by the distance m between the median lines -y-'g/ andrye-g/C In Vother words, as shown Tin Fig. 1, the pusher travel to complete the charging of the short billet Z, after engaging the latter with the yswitch 31, 32, i is first through a distance Z-l-a (to the point of pusher reversal -for the long billet L), and then through a certain further distance, here called m. Therefore on Fig. 8, the travel of each nut 18 and 21, in the period of their joint approach, lis measured by the distance 21, from rest position to meetingposition in always be the'sam'eg-therefore, from Fig. 8,

kin Vterms of total nut travel for the two cases comes the equation Solving this for m, I have @+aL-t2a=0+z+z+e+2m Inother words, the distance/m, Fig. 1, is

alwaysnone-half the differencey of the lengths a distance consequently each such shorter billet will come lto rest with-its longitudinal center coincidin with the center line Z -Z of the furnace, (the same as assumed for billet L), because that is theonly condition which establishes4 -g ,as the projection of length L beyond length Z. 1 j i the cases of the two billets Ll and Z, must e 6 5 pieces, and means controlledbythe length of In the operation of the' above. described mechanism, if at any time it is desiredto interrupt the action of'pusher 6 on any piece of stock, the operatorcan simply move the control switch 33 to an intermediate position, between the oil position shown in Fig.. 6 and the on. position. shown in Fig.i7,' Vthereby breakingthe circuit of motor 12; Also, before thef charging movement of anypiece of stock isV completecL/the pusher 6 can,.ii` desired, be reversed by the manual opening of a normallysclosedswitch 63, Figs. 6 and 7 in the circuit of the switch 20, -such opening breaking said circuitA and procuring deenergization of the solenoid to throw the reversing switch 34.. Y

I` claim, r 1 l. In mechanism of the class described, a charging. member, meansfor reciprocating said member -to produce, by its travel in one direction, the endwise charging movements ofv successively-presented pieces of different lengths, and automatic means for reversing said charging member in response to its ari, rival, on each charging movement, at a. point whose distance Jfrom a predetermined point is substantially one-halt1 the length of the piece being charged.

2. In mechanism, of the class described,a charging member, means for reciprocating said member toproduce, by its travel in one direction, the endwise charging movements of successively-presented pieces of different lengths, and means responsiveto the length of each piece or establishing the amplitude of the charging movement of said member for said piece. s

3. In mechanism of the class described, a reciprocatory member whose movements in one direction producethe endwise charging movements of successively-presented pieces of dilerent lengths, and means for varying the amplitude of such movements inverse ratio tothe lengths of saidfpieces.

Ll. In mechanism of the class described, a charging member, means for reciprocating said member to produce, byits travel in one direction, the endwise charging movements" of successively-presented variable 4,length pieces, and means responsive to the length of each piece for establishing the amplitude of the 'charging movement of said member on said piece. n

` 5. In mechanism of the class described, a reciprocatory member `whose movements in one direction procure the` endwise charging and positioning of Vsuccessively-presented pieces, and means controlled by the length of each piece for establishing the point atv which p the charging movement of said'member on said piece is terminated. A

6. In mechanism of the class described, a reciprocatory member for the endwise Acharging and .positioning of-successively-presented ositionino` of successiveli resented each piece for establishing the point atwhich the charging movement of said'member on said piece isreversed.V 7. In mechanism of the .class described, a reciprocatory member for the chargingr and pieces, adevice engaged byeach piece in its charg-V ing movement, and means responsive to the distance moved by said member in engaging each piece with said device for determining they amplitude of the subsequent charging movement of said Vmember on .said piece.

8. In mechanism ofthe class described, la reciprocatory member for the endwise charging and Vpositioning of successively-presented pieces or" different lengths, a device adapted to be operated by each piece in its charging movement, and means yfor proportioning the charging movement of said member, Jfollowing operation of said device by a piece being charged, to the amplitude of the charging movement that produced such engagement.

9. In mechanismV of the class described, a reciprocatory member for the charging and positioning of successivelyfpresented pieces of different lengths, and controlling means operative on each charging stroke of said member, toestablish the amplitude of said stroke in relation to the length of the piece being charged.` s f 10. In mechanism of the-class described, a reciprocatory member for the endwise charging and positioning successively-presented pieces of dierent lengths, controlling means operative oneach charging stroke kof said member for varying the length of saidstroke in relationto the length of the Vpiece being charged, and means for terminatingeach return stroke of said member always at the same point. v

v 11. In mechanism of the class described, a reciprocatory member for the endwise charg-Y ing and positioning successively-presented pieces of ditlerent lengths, the charging strokes of said member being variable in length, and thereturn strokes of said member terminating always at the same point, a device adapted to be engaged by each piece in its charging movement, said engagement requiring greater or less movement of said member Jrrom said terminal point, depending upon the length of ythe piece being charged, and means responsive to the amplitude oi the. movement producing said engagement for establishing the amplitude of Athe subsequent charging movement, lbefore reversal ofsaid member takes place.

12. In mechanism of the class described, apusher `for the vfeeding and positioning of successive unequal-length pieces, a pair kof membersl for controlling the strokepof said pusher, said members havingtheir maximum separation at the starting point of said pusher, and approachingv each other during said stroke for termination of the latter when izo they meet, and means for restraining thev approach movement of one of said members until the front end of the piece being fed reaches a point at a iiXed distance from said starting point, whereby the meeting pusher stroke, is determinedl by the length of said piece. p

13. In mechanism of the class described,.a

" pusher for the feeding and positioning of successive unequal-length pieces, a pair of controlling members having their maximum separation at the starting point of said pusher, andadapted for approach during the feeding stroke of said pusher to terminate said stroke when they meet, means for moving one of said members during the entire feeding stroke of said pusher, and means responsive to the length of the piece being fed for inaugurating the approach movement of the y other control member. i

14. In mechanism of the class described, a pusher for the feeding and'positioning of sucn cessiveunequal-length pieces, a pair of members movable toward each other during the feeding stroke of said pusher to control the amplitude of said stroke, the latter terminating when said members meet, and means controlled by the length of the piece( being fed for delaying the approach movement of one of said members. l Y

' l5. In mechanism of the class described, a pusher for the feeding and positioning of suc- ,y cessive unequal-length pieces, a pair of members movable toward eachother during the feeding stroke of said pusher to control the `amplitude of said stroke, the latter terminating when said members meet,means for sta-rting the approach movement of one of said members at the commencement of pusher operation, and means for starting the approach movement of the other member when the front end of the piece being fed reaches a point at a `fixed distance from the starting point of said pusher. Y

16. In mechanism of the class described, a pusher for the feeding and positioning of successive pieces of varying lengths, a pair of members movable toward each other during the'feeding stroke of said pusher to control the amplitude of said stroke, the latter terminating when said members meet, and means controlled by the length of a piece being fed for determining the periods of separate and joint approach of said members.

17. In mechanism of the class described, a Y

point of said 'members, and consequently the length of .variable-length. pieces,a member'at a hired distance from thestarting. ploint ofsaid feeding member, and adapted to beengagedLby each piece in its feedingmovement, whereby the length of travel of the feeding member, to effect said engagement, is inversely'related to the length of the-piece being fed, and means responsive to the amplitude of said travel for limiting the further feeding movement of saidfeeding member, .whereby to terminate thev` feeding movement of each piece Whenits longitudinal center arrives at av predetermined point. e Y

Y 19. In mechanism of the class described, a

pusher for operation on successive variablelength pieces, measuring means brought into action by the initial movement of a piece by said pusher, and means controlled by said measuring means to determine the total movement of said pusher in positioning said piece.

20. In mechanism of the class described, a pusher for-operation on successive variablelengthpieces, a reversible motor'for reciprocating said pusher, and'control devices responsive to the length of a piece for reversing said motor, to return said pusher to starting position. f

2l. In mechanism of the class described, a pusher for'operation on successive variablelength pieces, a reversible motor for reciprocating said pusher, a control device responsive to the length of a piece for reversing said motor, to return said pusher to starting position, and means responsive to said pushers return to starting position for stopping said motor. y

22. In mechanism of theclass described, a pusher for operation on succesive variablelength pieces, a reversible motor for reciprocating said pusher, control devices responsive to the length of a piece for reversingsaid motor, to return said pusher to starting position, and rmeans operable by the reversal of said motor to return said control devices to starting position. Y Y

28. In mechanism of the class described, a pusher for operation on'successive variablelengthpiece's, a motor for reciprocating said pusher, a reversing switch for said motor, and a control switch whose movement into one position sets said reversing switch to procure an operative stroke of said pusherby said motor,and Whose movement into another positionestablishes thecircuit of` said motor.

24E. In appartus for the endwise charging and positioning.ofVunequal-length pieces of stock, a charging pusher, -having the same lstarting point for each charging stroke, char- Y pusher for any given piece a total by substantially one-half the length of the piece being charged.

25. In apparatus for the endwise charging and positioning of unequal-length pieces of stock, a variable-stroke charging pusher, havingthesamestartingpointfor each charging stroke, characterized in this that means are provided for imparting to said pusher for any given piece a total charging stroke exceeding that for a longer piece by one-half the difference between the lengths of said' pieces, said means including a control device, at a xed distance from said starting point, adapted to be operated by front-end engagen ment of each piece therewith in the first part of each charging stroke of said pusher.

26. In apparatus for the endwise charging and positioning of unequal-length pieces of stock, a variable-stroke charging pusher, having the same starting point for each charging stroke, characterized in this that means are provided for imparting to said charging stroke exceeding that for a longer piece by one-half the difference between the lengths of said pieces, said means including a control device, at a fixed distance from said starting point,adapted to be operated by front-end engagement of each piece therewith in the first part of each charging stroke of said pusher and a stroke-terminating device, responsive to the operation of said control device, for proportioning the length of the final part of each charging stroke to said first part of each charging stroke.

27. In apparatus of the class described, a reciprocatory member for the feeding and positioning of successive variable-length pieces, a device substantially in the path of feed of said pieces and responsive.. to the arrival thereat of each pieces advancing end, and means controlled by said device for establishing the amplitude of the further feeding movement imparted to said piece by said member.

FRANK P. DAHLsTRoM.

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