US2819073A - Sheet feeding apparatus - Google Patents

Description

Jan. 7, 195% L. G. MURRAY 2,319,073

SHEET FEEDING APPARATUS" Filed April 20, 1955 5 Sheets-Sheet l INVENTOR. Z10 YD 6- Mummy BY JW, HMM +Mv ATTORNEYS Jan. 7, 1958 L. e. MURRAY 2,819,073

SHEET FEEDING APPARATUS Filed April 20, 1955 5 Sheets-Sheet 2 IN VEN'I'OR. [10m 6 MUERA v ATTOPNQYS Jan. 7, 1958 1.. G. MURRAY 2,819,073

SHEET FEEDING APPARATUS Filed April 20, 1955 5 Sheets$heet 3 4 J J INVENTOR.

[Zora 6. Maze/PAY 'ay g d jw Jan. 7, 1958 L. G. MURRAY SHEET FEEDING APPARATUS 5 Sheets-Sheet 4 Filed April 20, 1955 JNVENTOR. [Zora a. MUIEEA Y dZW M, M,

A TTOE/VEYS' Jan. 7, 1958 L. G. MURRAY SHEET FEEDING APPARATUS Filed April 20, 1955 5 Sheets-Sheet 5 JNVENTOR. [Zora GJVUEEAY Wm M A 7 TOE/V575 SHEET FEEDKN'G APPARATUS Lloyd G. Murray, Youngstown, @hio, assignor to The Aetna-tandard Engineering Company, Pittsburgh, Pa, a corporation of @hio Appiication April 2d, 1955', Serial No. 5132,6155

l Ciainrs. (Cl. 271-41) This invention relates to the handling of steel sheets or the like and more particularly to an improved apparatus for removing such sheets from one or more stacks or piles and feeding them to other processing apparatus, such as a tinning machine or pickling tanks.

After sheet steel material leaves the forming rolls it is usually cut into individual units of the desired length and these units or sheets are arranged in stacks or piles. Further processing operations, such as tinning, are commonly performed on such sheets and problems are encountered in feeding them in the proper and most efiicient manner from the stacks to the tinning machine or other apparatus. As the sheets must pass through the tinning machine or the like individually and spaced apart, i. e., not overlapped or doubled, it is necessary to provide means for removing them from the stacks one at a time and transmitting them as rapidly as possible to the feed rolls which carry them along to the next processing apparatus.

The width of the stacks of sheets that are to be handled by the feeding apparatus necessarily varies from time to time, depending on what size sheets are being processed, and accordingly it is an object of this invention to provide apparatus whereby either single relatively wide sheets or sets of several relatively narrow sheets may be fed to the next machine from one or several stacks automatically and without change or adjustment of the feed apparatus.

Other objects of my invention include the provision of sheet feeding apparatus of the type referred to whereby single sheets will be removed from each of one or several stacks of sheets and fed to the succeeding processing apparatus with a minimum delay between successive sheets or sets of sheets, and in such a manner that a new cycle of the feeding apparatus will not start until the sheets being fed are completely out of the way; the provision in sheet feeding apparatus of the type described of means whereby the feeding apparatus may not be started unless a suitable current supply is available, and whereby the feeding cycle will automatically repeat promptly after a given sheet or set of sheets has been fed; the provision of sheet feeding apparatus which will automatically adjust for sheets of various lengths so that, regardless of the length of the sheets being fed, the cycle will repeat immediately after the sheet, or set of sheets, being handled has moved out of the path of the feeding apparatus; and the provision of a fully automatic sheet feeding apparatus which is efiicient in operation, requires a minimum of maintenance and repair, and will operate continuously over long periods of time without attention or adjustment.

The above and other objects of my invention will appear from the following description of one embodiment thereof, reference being had to the accompanying drawings in which:

Figure l is an illustrative side elevational view of my feeding apparatus, the pickup arms and suction heads being shown in fully advanced positions;

arrests Patented use. 7, 1958 Figure 2 is a view similar to Figure 1 but illustrating the pickup arms and suction heads in fully retracted position, a sheet being shown in engagement with the magnetic rolls and being advanced toward the succeeding processing apparatus;

Figure 3 is a diagrammatic illustrative elevational view showing several stacks of sheets in feeding position, the upper magnetic roll, the contactor rings on the upper magnetic roll shaft, and the electrical connections leading from the rings to the control mechanism;

Figure 4 is an illustrative wiring diagram showing the electrical controls and the solenoid which operates the valve means for controlling the advancing and retracting movements of the pickup arms, the various elements being shown in their completely off or non-operating positions and conditions;

Figure 5 is a view similar to Figure 4 but illustrating the elements of the control mechanism in the positions they assume after the main switch and starting button have both been moved to the on position, but While the pickup arms and suction heads are still fully retracted, ready to start their advancing movement;

Figure 6 is a view similar to Figure 4 but illustrating the positions and conditions of the elements after the pickup arms and suction heads have advanced to their final forward position and are just ready to start retracting to remove the top sheet from each stack;

Figure 7 is a view similar to Figure 4 but illustrating the positions and conditions of the elements after the pickup arms and suction heads have retracted to a point just beyond where the suction heads release the sheets but before the arms have reached fully retracted position; and

Figure 8 is a view similar to Figure 4 but illustrating the circuits, etc., when the pickup arms and suction heads are in their fully retracted positions; the sheet or sheets being still engaged and fed by the top magnetic roll while the pickup arms are held in retracted position ready for repetition of the feeding cycle immediately after all the sheets have left the magnetic roll.

As will be seen from Figures 1 and 3, my sheet feeding apparatus is mounted in a frame structure or housing F having spaced end panels 1 and 2 suitably supported on the floor or foundation and maintained in proper relationship to each other as by transverse members 3 (Figure 3). In Figure 1 the upper portion of the end panel 2 has been broken away more clearly to illustrate the structural arrangement of the apparatus.

Extending across between the end panels 1 and 2 is an angularly mounted stack support structure 4 on which one or more stacks or piles P, P and P" of sheets are supported in slightly inclined position. Also extending between and supported by the end panels 1 and 2 are the main pickup arm support shaft 5, the shaft 6 for the lower magnetic rolls 7, the shaft 8 for the upper magnetic rolls 9, and the drive shafts for the two sets of takeoff rolls lit-l1 and 12-13. The sheet guides or deflectors 14 and 15 are also suitably supported between the end panels 1 and 2. p

In Figure 2 a single sheet S has been removed from the stack P and moved into engagement with the magnetic rolls 7 and 9 by the mechanism and in the mannor to be later described. As the magnetic rolls, during operation, are continuously driven in the directions indicated the sheet S will be fed upwardly thereby and its upper end will engage the guide or deflector 14 which, in cooperation with the lower deflector or guide 15, will direct the leading edge of the sheet S into the takeofi rolls ltd-ll which will carry it on to the second set of takeoff rolls 12l3 and thence to the next processing apparatus. In Figure 2 a sheet S, which has been removed from the stack P and advanced by the magnetic movement the collar 23, at first, merely slides on the tubular stem 24 and the spring 26 holds the lip 25 of the vacuum head H firmly against the sheet S. During this initial movement of the arm 16 the piston 52 will be moved to the right in the cylinder 51. This movement will, because the pipe connections are air-tight and because the valve 59 is closed, produce a reduced pressure in the piping connections 4-9, 59, 48, d6, d5, 44 and 24 which lead to the suction grip member 25. Thus, by the time the end face of collar ZSengages the adjustable stop nuts 24' on the tubular stem 24 sutficient vacuum will have been produced within the suction grip member 25 to firmly adhere the sheet S thereto. Now, as the arm 16 continues its retracting movement it, together with one or more of the other pickup arms and suction heads, will pick the single sheet S off of the stack P and move it bodily into engagement with the magnetic rolls 7 and 9. During this transfer movement the sheet S is, in effect, hung or suspended from the suction heads and is generally vertically disposed.

At the time the sheet 8 reaches a plane extending tangent to both of the vertically spaced magnetic rolls and engages these rolls, or very shortly thereafter, the valve 59 is opened by engagement of the contactor finger 62 with the operating stem or plunger 61 of the valve. The exact timing of the opening of the valve 59 may be regulated by suitable adjustment of the position of the finger 62 at the end of the extension 55 of the operating arm 55, it being seen in the drawings that finger 52 is provided with a screw slot connection to permit such adjustment.

As soon as valve 55 is opened, the vacuum system is vented to atmosphere and the suction at the head H is broken. This, of course, causes the lip portion 25' to be released from its grip on the sheet S and the pickup arm to then continues to move in retracting direction until it reaches the fully retracted position shown in Figure 2. fully retracted and fully advanced positions of the arm 16 may be established and controlled by any suitable stop means which may be within the cylinder 25 or at any other suitable location.

During the advancing movement of the arm 16 from the position shown in Figure 2 to that shown in Figure 1, the piston is moved to the left in the vacuum cylinder 51. As the valve 59 is closed at this time this will cause air to be discharged out through the open lip portion 25' of the suction head H. When the lip 25 engages the sheet S on the outer face of the stack l its advancing movement is of course stopped. However, the arm 16 continues to advance during the time the spring 26 is being compressed. Due to the form and natural characteristics of the lip portion air will be discharged between the lip and the sheet without excessive resistance until. the final advance position of the arm 16 is reached as seen in Figure 1. However, during the retracting movement of the arm, as previously explained, reduced pressure is immediately created within the vacuum head H and this reduced pressure is immediately eifective to produce the required grip on the sheet. The provision of the spring as not only ermits the arm to to continue to move after the va" engages the sneet so that there may n it be an initial movement in the reverse direction to create a vacuum to cause the sheet to be attached to the head H, but also automatically compensates for the varying position of the top sheet of the stack P as sheets are removed one by one therefrom.

For control purposes to be later described, a reverse limit switch 65, diagrammatically indicated on Figures 1 and 2, is supported on the end panel 2 and has an operating member d projecting outwardly therefrom and adapted to be engaged by a pin 66 on the arm 55 when said arm reaches its fully retracted position (Figure 2). In like manner a forward limit switch 67 is mounted on end panel 2 and has an operating member 67' which, as seen in Figure 1, is engaged by the pin 66 when the arm 16 reaches its fully advanced position.

Having described the pickup and feeding portions of my apparatus and explained generally their mode of operation, the mechanism for controlling and timing the functions and operations thereof will now be described.

The electrical circuits and the various elements of the control apparatus are diagrammatically shown in Figures 4 to 8 inclusive, the several views being similar but illustrating the connections, etc., which are established during several different phases of the operating cycle. Figure 3 illustrates schematically the contactor rings (to be later described) on the upper magnetic roll shaft 8 and the connections thereto.

in Figure 4 the control mechanism is shown in full off or non-operating position. The main current supply to the apparatus comes through power lines 70--71 which are connected to a suitable source such as 220 volts A. C. The main switch 72, when open as seen in Figure 4, breaks the main power supply and accordingly the apparatus is completely inoperative. A transformer 73 having a primary 73 and a secondary 73" may be considered as the source of solenoid energizing current. The secondary "73 supplies a reduced voltage (for example 110 volts A. C.) to the lines or conductors 74 and 75 in the operating circuit. These conductors 74 and 75 extend to the primary 76 of a second transformer 76, the secondary '76 of which provides the source of control current and is connected to lines or conductors 77 and 78 in the control circuit.

Connected across the lines 74 and 75 is the energizing coil of a relay [9. This relay 79 has two normally open (i. e., open when the relay is de-energized) contacts 79 and 79". The connection 86, which includes the energizing coil of relay 79 and extends between lines 74- and 75, also includes the starting push button or switch 81, a stop push button or switch 82 and the contacts 83 of a relay $3 the energizing coil of which is connected across between lines '77 and 78 by a conductor 84. It will be understood that although the various relays included in Figures 4-8 are shown with their energizing. coil portions spaced from their contact portions there are the usual operating means whereby these contacts are opened or closed when the relays are energized or tie-energized.

Another relay 85 has its energizing coil connected across lines 74 and 75 by a conductor 68. Relay 85 has a normally open contact 85 disposed in the conductor 68 which also has, in series arrangement therein, the normally closed forward limit switch 67, the contact 79" of relay 79, and the normally closed contact 86' of relay 86. Connected around the contacts 35' and 86 by a conductor 87 are the normally open reverse limit switch 65 and the normally closed contact as" of relay 86.

As best seen in Figure 3, the upper magnetic roll shaft 8 carries three pairs of contactor rings, to'wit: 37-88, so 9d, and 91-92. These contactor rings are of a diameter equal to or just slightly larger than the diameter of the magnetic rolls 9 and are adapted to be engaged by the sheets being handled when these sheets are held against the magnetic rolls. it will be understood that the sheets will effect electrical connection between the adjacent rolls of each pair so long as they are in contact therewith. Brushes 37, S8, 8?, My, )1 and 92 make electrical contact with their respective contactor rings. These brushes are also shown on Figures 4-8 and it will be seen that one brush of each pair, namely brushes 88', and @2, are connected by a conductor 93 to the .line 77 while the other brush of each pair, namely brushes $7, 89, and $1, are connected to line 73 through conductor 94 in which the energization coil of relay 86 is disposed. Conductor 77 is connected to the machine frame P which in turn is grounded at ran for purposes which will be later explained. The solenoid M is, of course, in the operating circuit and is connected around the energizing coil of relay 85 by conductors 95 and 96. As has been previously explained this solenoid M actuates the control valve V of the fluid pressure cylinder 27.

'51! r As enn Figu 4 he main w tch 22. s. onaa- T b isa sc pen... W enthis does not flow t ro h he pe .e 1 1 d 1 e c). or hro gh h n r es 717. and 18;, etc.) and the relays 7'19, 83, 35, al ude-energized, However, because the pickup acted position n h p n 6 e op rating e er .5 c t e ch. w ich s. n r ally- ;ble; spr ng means, is; closed as is indi- The forward limit switch, and all of the relay contacts are in their normal positions which have ee noted ab ve.

a ame the Q0 m hani m, is illustrated in h conch on which obta -S fierthemainswitch 72 has been .l ses an aft r he aring pu h butt n h n Operatedto, complete its contacts in the conductor b ll. The pickup; arm, 16 has, however, not yet left its fully etra te position; f F gure. but is ju t a ou to do. so.

As,- soon as the, main switch, 722 is closed the circuit through the primary 7.6 of transformer 76 is completed causing current of reduced voltage (for example 24 volts) iromthc secondary 76" to be applied to. the concluctors and; 7:8; and toiiow through conductor 84 and the, actuating coil of relay 83. Upon relay 8,? being thus energized its normally. opened contact 8-3 immediately closes as seen in Figure 5. The start push button 81 and the stop switch 82 also now being closed, the circuit is completed through the energizing coil of relay 79 and the normally open contacts 79 and 79" thereof imn1edi-. ately close, as. is. also seen inv Figure 5. When contact 7% closes it locks in. the. relay 79 so, that this relay continues to, be energized even after pressure on the start push button 31 is removed and it returns to its open or off position. When, the contact 79. in conductor 68. closes the circuitto. the energizing coil of relay 85 is completed from conductor '24: through the still closed reverse limit switch 65, the normally closed contact 86" of relay 36, the. conductor 8:75; the. closed contact 79", the conductor 6& and the normally closed forward limit switch 67 to conductor 75-. As soon as relay 85. is energized its contact 85., which lies in conductor 68, immediately closes thus locking in relay 35. and holding it energized even after .thepickup arm 16. moves away from. the reverse limit switch 65, thus permitting switch 65. toreturn to its normally open position. This movement of the pickup arm 16. occurs as soon as. contact 79." closes as this, in additionv to energizing-the relay 85, also completes the circuit to. and energizes the solenoid M, causing it immediatelyto shift the valve V irom the position of Figure 2, .in which fluid pressure. is applied to hold the arm is in retracted position, into the position of Figure l in which fluid pressure is applied to movepiston- 23, piston rod 29, and pickup arm 16 in advancing direction. As noted above, as soon as arm 16 moves forward a very slight distance the reverse limit switch 65 will return to its normal or open position but relay 85 stays energized, being locked in by its contact 85, and the solenoid M continues to be energized.

Thus the pickup arms will continue to advance until they. reach fully. advanced position (Figure l) at which time the pin 66 on arm 16 engages the operating member 67" of'ncirmally. closed for-ward limit switch 67, moving same into open position. When this occurs the condition shown in Figure 6 will be produced.

As the circuit to. the solenoid M is broken upon the opening of the forward limit switch 67 the valve V will be moved by the spring43 from the pickup arm advancing position of Figure 1 into the pickup arm retracting positiou f Figure It will, be understood that in the conditionofFigur 6 the start push button til will be open as the opera s, pressure thereon will have been released. H ver elay 1 be energized, being locked in by contact 79". When fiorwapdiimit switch 67: opens,

(ill

W153? 3 5 s tiene gize a t con act 85 will return to its icrma v ac posi ion. The no mal y pen reverse im w t h 51 il r ma n uri g r ac ingmovehe arm in, relay will, remain energized thus hold its contact 33' closed, and. until the sheets engage the contactor rings $72., relay 86 will remain. de energized holding its normally closed contacts 86, and 36/ in closed position.

As has been previously explained, the suction heads pick up the top sheet from the stack P because of the suction produced by movement of the piston 52 in the vacuum cylinder 51-, As, the pickup arms retract the sheet, or sheets, are lifted and carried into contact with the magnetic rolls '2' and 9. Just as. the sheets engage these rolls the contactor finger 62 on arm 55 opens the vacuum relief Valve 5??- thus releasing the suction heads H from the sleets and permitting the pickup arms to. continue to retract.

As soon as a sheet is, caused to engage the upper mag.. nctic roll 9, and thus to complete the circuit between. adjacent pairs of the contactor rings 8Z 3$, til.9tl, or 911x412, the condition shown in Figure 7 is produced. As the arm 3.6, together with the arm 55 and pin 66, thereon have moved away from and out of engagement with the operating member 67 of forward limit switch 6 7, this switch has, returned to its normally closed position. The circuit to the energizing coil of relay 86 has however been completed from conductor 7'7 through the conductor 93, the brushes till, 96, 92, contactor rings 88, 89, Sit), the sheet or sheets, conductor rings 87, 33, $9 brushes S57, 89., 91", and conductor Q4 to conductor "73. it will be understood that the circuit to relay as will be completed whether there are three sheets, S, S and S, in engagement with the respective pairs of contactor rings illustrated in Figure 7 or only a single sheet is being handled and is. in engagement only with one pair of con tactor rings.

The machine frame F is connected to the conductor 77 and is also. grounded at 10%, and thus the sheetsS, S and S" are also grounded through engagement with the magnetic rolls?" and 9. Contactor rings 8'7, 89' and 91, which are. connected; to, conductor 94'. and thence to conductor 8: through relay 86, are electrically connected to the upper magnetic roll shaft 8. which is also grounded through the machine frame. Contactor rings 88, l d and 92, which are connected to conductor 77 through conductor 93 are insulated from. the shaft 8. Thus when sheet engages one of the magnetic rolls and one of the contactor rings $57, 89 or 91, the circuit through relay 86 will be cornpleted even though contact is not made or maintained between the sheet and another-contactor ring of any of the three pairs.

The condition illustrated in Figure 7 is that which obtainsjust after asheet or several sheets have been brought into engagement with the magnetic rolls but before the pickup arms have moved to their fully retracted positions. in Figure 8; the condition is shown after the pickup armto, has reached fully retracted position as seen in Figure 2. Normally open reverse limit switch has now been closed by engagement of pin 66 with the operating member- 65 of the, limit switch. However, as sheet or sheets are still; in contact with the upper magnetic roll 93nd with one or more pairs of the contactor rings ill-92, the relay as, is still. energized and its contacts 66 and 36" are still open. Thus the circuit to relay is held open and the solenoid M remains de energizcd. Accordiuglythe valve V remains in the position of Figure 2 and the operating fluid, pressure in cylinder .27 holds the pickup arms and associated. parts in their fully retracted positions as long as. the circuit to relay 36 remains closed. This occurs until the trailing edge of the last sheet being handled leaves the upper magnetic roll 9 and breaks all connec tions, either between a pair of contactor rings or one 02 the. contactor rings 87, 89. or 975. and the ground, to relay 86. When the last sheet so. leaves the contactor,

rings the relay 86 is immediately de-energized permitting its normally closed contacts 86' and 86" to reclose. This action will return the mechanism and the circuits to the condition shown in Figure (except that push button 81 will be open) in which the solenoid M is energized to shift the valve V into arm advancing position and is locked in by contact of relay The cycle above described then automatically repeats itself.

It will be observed that unless there is a suitable supply of low voltage current between the conductors 7'7 and '73 it will be impossible to start the feeding apparatus even though the main switch '72 and starting button S1 are both closed. This safety feature results from the fact that unless the relay $53 is energized by current in the circuit 77-'73 its contacts 233 will be open and it will be impossible to energize relay 79 and start the cycle of operation even though the push button start switch 81 is actuated. By providing the contactor ring arrangement advancing movement of the pickup arms from their fully retracted positions is positively prevented until after the last sheet being handled has moved upwardly away from the top magnetic roll and thus out of the path of the vacuum heads, etc. My control mechanism not only prevents the pickup arms from advancing while a sheet is in the way but also insures that the pickup arms do advance immediately after the path is cleared so that there is a minimum of time delay feeding the sheets to the next processirr apparatus.

The function of the contact 36 of the relay 86 is to reduce the possibility of cobbling which might occur if only the contact as" were actuated by relay 86. if only a single contact as" were employed and, with the arm 16 in retracted position and the reverse limit switch 65 ield closed, the sheet should inadvertently and accidentally be jarred or moved out of circuit completing contact with the contactor rings, the relay 86 would immediately be die-energized and its contact d6" would reclose. This would complete the circuit to the solenoid M which would be energized moving the valve V and starting the arm in to advance. However as soon as this advance started reverse limit switch 65 would be opened thus breaking the circuit to the solenoid M and causing the arm to to be returned to full retracted position and the reverse limit switch to again be closed. This cycle would repeat and oscillating or cobbling action would occur as long as the sheet did not complete the circuit to the relay By providing the contact 86 as illus hated, it all contact between the sheets and the contactor rin s is momentarily broken with the pickup arms in full retracted position and reverse limit switch 65 closed, both the contacts dd and 36" would immediately close because of tie-energizing relay When this occurs solenoid M will be energized as will also relay 85 which will close l'lCl become sealed in by closing of the contact 85. Now the solenoid M will remain energized even after the arm lid starts to advance and reverse limit switch 65 opens. However, as soon as the sheet resumes contact with the contactor rings the solenoid M will be de-energized and the pickup arms again retracted. Thus with the dual contacts as and 36 there will be only one movement of the contact arms out of full retracted position and back to retracted position during any one given time that the sheets are momentarily out of engagement with the contactor ring, and rapid vibration or cobbling is prevented.

From the above description of the arrangement and mode of operation of my improved sheet handling appa ratus it will be apparent that sheets or sets of sheets will be fed successively one after another with a minimum space therehetween regardless of the length of the sheets being fed. Furthermore the machine willcontinue to operate as long as there are sheets in the'stacks to be picked up and moved. When it is desired-to stop the operation it is only necessary to operate the stop push button 32 which breaks the circuit to relay 79 which in turn causes the contacts 79 and 7'9 to open. The open- 10 iug of contact 7E unlocks relay '79 and opening of contact 79 tie-energizes relay and solenoid M. De-energizing the solenoid causes the pickup arms to be re tracted while de-cnergizing the relay 85 also opens the contact 85'. Thus the apparatus is rendered inoperative and will not start again until the start button d ll is closed.

Although I have described the illustrated embodiment of my invention in considerable detail it will be understood that modifications and variations may be made in the form and arrangement of the various elements which make up my improved sheet feeding apparatus. I do not therefore wish to be limited to the exact arrangement herein shown and described but claim as my invention all embodiments thereof coming within the scope of the appended claims.

I claim:

1. Apparatus for feeding electrically conductive sheets of magnetic material including, a stack support for holding a stack of sheets in generally vertical position, a magnetic roll adjacent said stack support, a pickup arm having a suction head supported at one end thereof, said pickup arm being mounted for movement in advancing and retracting directions between a position in which said suction head is more remote from said stack support than said roll and a position in which said suction head is closer to said stack support than said roll and is adapted to engage a sheet on said stack support, means for creating suction at said pickup head during a portion of the movement of said arm in retracting direction whereby a sheet will be picked up by said pickup head and removed from said stack, valve means operable by movement of said pickup arm for relieving the suction at said suction head substantially when a sheet carried thereby engages said magnetic roll during movement in retracting direction and before said arm reaches the end of said movement in retracting direction, means for imparting movement to said pickup arm in said advancing and retracting direction, and control means for said pickup arm advancing and retracting means whereby said arm, after being fully retracted, will start movement in advancing direction immediately upon, but not until, contact between the sheet being fed and said magnetic roll is broken.

2. Apparatus for feeding electrically conductive sheets of magnetic material including, a stack support for holding a stack of sheets in generally vertical position, a pair of vertically spaced magnetic rolls adjacent said stack support, a pickup arm having a suction head supported at one end thereof, said suction head having a resilient lip portion, said pickup arm being mounted whereby advancing and retracting movement of said arm will effect movement of said suction head between said rolls toward and away from said stack of sheets, means for creating suction at said pickup head during retracting movement of said arm whereby a shee will be picked up from said stack, automatic means for cutting off the suction at said suction head during said retracting movement when said resilient lip portion thereof is substantially in a plane tangent to both of said magnetic rolls and before said arm reaches the end of said retracting movement, means for advancing and retracting said pickup arm, and control means for said arm advancing and retracting means whereby said arm, after being fully retracted, will start movement in advancing direction immediately upon, but not until, contact between the sheet being fed and the upper one of said magnetic rolls is broken.

3. Apparatus for feeding electrically conductive sheets of magnetic material including, a stack support for holding a stack of sheets in generally vertical position, a pair of vertically spaced rolls adjacent said stack support, magnetic means associated with upper one of said rolls for holding a sheet in engagement therewith, a pickup arm having a suction head supported at one end thereof, said suction head having a resilient lip portion, said pickup arm being mounted whereby advancing and retracting movement of said arm will effect movement of said a, macro l d suction; head,. b etween:said; rolls: toward and away fromv said stack.- of 1 sheets,-, means for; creating-- suction at 1 said: pickup head, during retracting movement of. said; and whereby a sheet will-be, picked up from said-:stack, autos ma-ticmeans for. cuttingrofi the suction at said suction head-during, said-retracting movement when said resilient lipportion thereof is substantially. in a plane tangent to both: ofsa:id,= rolls and'beforethe endnof saidretracting movement, means for advancing and retracting saidpickup armnand-control-means for said: arm advancing and retracting means whereby said: arm; after being fully retracted, will; start movement in, advancing, direction immediately, upon, but not until, contact between the sheet-:bfeing fed-andisaid upper magneticroll is broken;

4. Apparatus for feeding electrically conductive sheets of magnetic material including, a, stack support for holdingaistackiofs sheets in. generallyverticalposition, a pair ofx vertically,- spaced magnetic; rolls adjacent said stack support,,atpickupiarmhaving a suction head supported atronetendz-thcreof, said:suetion head having a resilient lip portion, said; pickup arm. being mounted whereby advancing: and retracting, movement of said arm will eifectmovement of said'suction head-between said rolls towardandaway from said stack of. sheets, acylindcr,

piston in said cylinder, operating connections between said pistonand said pickup arm, fluid pressure conducting; connections between saidicylinder and said suction head; said pistonbeing adaptedto move. in said cylinder during; retracting movement'of. said arm to produce a reduced-pressure in said fluid pressure conducting connections and 'suction headwhereby' asheet will be picked up frornisaid stack, automatic means for cutting off the suctionatsaid suction head during said retracting movement when said-resilient lipportion thereof is substantiallyqin: atplane; tangent toboth of said magnetic rolls 'and'bcfore the end of said retracting-movement, means for advancing and retracting said pickup arm, and controlrmeansfor said arm advancing and retracting means whereby. saidarm, afterv being fully retracted, will start movementrin advancing direction-immediately upon, but notuntil, contact betweenthe sheet beingfed-and the upper oneof said magnetic rolls is broken.

5; Apparatus for feeding electrically conductive sheets ofmagnetic materialincluding, a stack support for holding astack of sheets in generally vertical position, a pair of. vertically spaced magnetic rolls adjacentisaid stack support, a pickup arm having'a suction head supported atmone end thereof, saidsuction head-having a resilient lip portion, said'pickup arm being pivotally mounted whereby advancing and retracting movement of said arm will"effect movement'of said suction head between said rolls toward and away from saidstack of sheets, a cylinder, a piston in said cylinder, operatingconnections between said piston and said pickup arm, fluid pressure conducting connections between said cylinder and said suction head, said piston being adapted to move in said cylinder during retracting movement of said arm to produce a reduced pressure in said fluid pressure conducting connections and suction head whereby a sheet will be picked up from said stack, a normally closed atmospheric vent valve in said fluid pressure conducting con nections, an operatingarm supported for movement withsaid pickup arm, means on said operating arm disposed to engage and open saidvalve when said resilient lip portion of said suction head is s'ubstantiallyin a plane tangent to both of said magnetic-rolls during retracting movement-of said arm. and before the end of such movement, means for advancing and retractingsaid pickup arm, and control: means for saidJarm: advancing and retracting means whereby said arm, after-being'fully retracted, will be maintained fullyr retracted until f contact between the shect beingfed and the upper oneof said:mag netic= rolls isibroken 6-. Apparatus for feeding; electrically conductivei sheets:

ofv magnetic material, including,- means for supporting; av

stack: of: sheets; in generally vertical position, a pair, of: vertically-v spaced rolls: adjacent; said" stack: support, mag? neticsmeans;associated with the upper one of saidrolls for holding, a sheet inen-gagement therewith, a pickup 1 armhavinga suction BhCEd'SllPPOIlICd at one end thereof,

said" suction: head: having a resilient lip portion, said,

pickup;arm=being: pivotally mounted whereby advancing and retracting movement of saidarm will effect move, ment of; saidsuction head between saidrolls toward and away from saidistaclc of 'sneets,a cylinder, a piston in said. cylinder, operating connections between said piston andisaidnpiclt upcarm, .fluidpressure conducting connections between said; cylinder and said suction head, said pistombeing adapted-to move in said cylinder during retracting: movement ofsaid' arm to produce a reduced pressure in said fluid: pressure conducting connections andzsuctiona head whereby a sheet will be picked up from saidrstack, automatic means'for cutting off the suction,at7said1suctionthead during said retracting movement whenzsaid'resilient lip portion thereof is substantially.in a;plane tangent to. both of said rolls and before theend'iofLsaid 'retracting'movement, means for advanc ir1g=and retractingsaidwpickup arm, and control means for said'iarmzadvancing'and retracting means whereby i saicltarm after being fu-llyrretracted, will be maintained fully retracteduntilcontactbetween the sheet being fed and said .uppermagnetic roll is broken.

7. In combination in apparatus for feeding electrically,

conductive sh'eetsof'magnetic material, a stack support for holding.aistacktofzsheets, a magnetic roll adjacent said support, means:for.driving said roll to feed asheet in engagement therewith", a pickup arm having a suction head, at one.- end and supported for advancing and retracting movement relative to said sheet support, power means for efiecting said advancing andretracting movement, asolenoid, reversingmeansfor changing said power means from advancingito retracting movement and viceversa', operating connections from said solenoid to said reversing means, an operating circuit including electrical connections froma source of energizing current to said solenord; a normally open reverse limit switch in said operating circuit, means for closing said reverse limit switch whenisaid pickup arm is in full retracted position,

a normally closed contact in said circuit in series withsaidsolenoid and said reverse limit switch, and means for holding-said'normally closed contact open when a sheet is in-engagement with said'magnetic roll whereby said solenoid may be energized to initiate advancing movementofIsaid' pi-ckup=armonly when no sheet engages .said magnetic roll'and said pickup arm is in full retracted positions 8. In=-combination in apparatus for feeding electrically conductive sheets of magnetic material, a stack support for holding a stack of sheets, a magnetic roll adjacent said support, meansfor driving said roll to feed a sheet in engagement therewith, a pickup arm having a suction head at one-end and supported for advancing and retracting-movementrelative to said sheet support, power means for eifectingsaid advancing and retractingmovement, a solenoid, reversing means for changing said power meansfr'om' advancing to retracting movement and-'vice-versa, operating connections from said solenoid to saidreversing-means,- an operating circuit for'said' solenoid including electrical-connections from a source'- of energizing current to-said solenoid, a normally closed forward'limit-sw-itch insaid operating circuit disposed to be. moved into and held in open position only while said pickup: arm is in fulladvanced position, a normally open. reverse limit xswitchxin'said operating circuit'dis:

posedto, betmovedintozand held in closed position only when;sa1d:: pickupaarrnrz is in: full retracted position, a

controltcircuittfdr;said solenoid including electrical connections: to :aasource; of '1 control :current, normally open contactvmeansninzxsaid 3001111'01'. circuit and supported ad- I. jacent said magnetic roll", said contact means being'dio 13 posed to be engaged and closed by a sheet only while said sheet is being fed by said roll, and a relay in said control circuit adapted to be energized when said normally open contact means is closed by a sheet and deenergized when said contact means is open, said relay having a normally closed contact in series with said reverse limit switch whereby said solenoid may be energized only when said reverse limit switch is closed and said second relay is de-energized.

9. In combination in apparatus for feeding electrically conductive sheets of magnetic material, a stack support for holding a stack of sheets, a magnetic roll adjacent said support, means for driving said roll to feed a sheet in engagement therewith, a pickup arm having a suction head at one end and supported for advancing and retracting movement relative to said sheet support, power means for effecting said advancing and retracting movement, a solenoid, reversing means for changing said power means from advancing to retracting movement and viceversa, operating connections from said solenoid to said reversing means, an operating circuit for said solenoid including electrical connections from a source of energizing current to said solenoid, a normally closed forward limit switch in said operating circuit disposed to be moved into and held in open position only while said pickup arm is in full advanced position, a normally open reverse limit switch in said operating circuit disposed to be moved into and held in closed position only when said pickup arm is in full retracted position, a control circuit for said solenoid including electrical connections to a source of control current, normally open contact means in said control circuit and supported adjacent said mag netic roll, said contact means being disposed to be engaged and closed by a sheet only while said sheet is being fed by said roll, a first relay in said control circuit adapted to be energized when said normally open contact means is closed by a sheet and de-energized when said contact means is open, said first relay having a contact in series with said reverse limit switch, said relay contact being closed when said first relay is de-energized and open When said first relay is energized whereby said solenoid may be energized only when said reverse limit switch is closed and said second relay is de-energized, and a second relay in said operating circuit, said second relay having a contact in said operating circuit in parallel with said reverse limit switch, said second relay contact being open when said second relay is de-energized and closed when said second relay is energized whereby, when both said normally open contact means in said control circuit is closed and said reverse limit switch is closed, said second relay will be locked in and said solenoid will remain energized until said normally closed forward limit switch is opened upon said pickup arm reaching full advanced position.

References Cited in the file of this patent UNITED STATES PATENTS 1,442,718 Free Jan. 16, 1923 1,457,830 Gerhardt June 5, 1923 2,162,580 Hopkins June 13, 1939 2,197,817 Theiss Apr. 23, 1940 2,661,208 Fowler Dec. 1, 1953 2,661,948 Montgomery Dec. 8, 1953

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