US2594704A - Conveyer mechanism for printing presses - Google Patents

Description

April 29, 1952 R. F. ABERLE CONVEYER MECHANISM FOR PRINTING PRESSES Original Fild Sept. 20, 1946 9 Sheets-Sheet l April 1952 R. F. ABERLE 2,594,794

CONVEYER MECHANISM FOR PRINTING PRESSES Original Filed Sept. 20, 1946 9 Sheets-Sheet 2 A ril 29, 1952 RF. ABERLE CONVEYER MECHANISM FOR PRINTING PRESSES Original Filed Sept. 20, 1946 9 Sheets-Sheet 3 April 1952 R. F. ABERLE 2,594,704

CONVEYER MECHANISM FOR PRINTING PRESS ES Original Filed Sept. 20, 1946 9 Sheets-Sheet 4 7 [750672507 20 fif yer Ze April 29, 1952 R. F. ABERLE CONVEKER MECHANISM FOR PRINTING PRESSES Original Filed Sept. 20, 1946 9 Sheets-Sheet s wwm w fry/yew? merle M 71% April 1952 R. F. ABERLE 2,594,704

I CONVEYER MECHANISM FOR PRINTING PRESSES Original Filed Sept. 20, 1946 I 9 Sheets-Sheet 6 April 29, 1952 R. F. ABERLE CONVEYER MECHANISM FOR PRINTING PRESSES Original Filed Sept. 20, 1946 '9 sweets-sheet 7 Ap 1952 R. F. ABERLE r 2,594,704

CONVEYER MECHANISM FOR PRINTING PRESSES Original Filed Sept. 20, 1946 9 Sheets-Sheet s f 4 a U" 71 l b t, N I,

Q I m NI Q! April 29, 1952 R F. ABERLE 2,594,704

CONVEYER MECHANISM FOR PRINTING PRESSES Original Filed Sept. 20, 1946 9 Sheets-Sheet 9 Patented Apr. 29, 1952 CONVEYER "MECHANISM FOR PRINTING PRESSES Roy F. Aberle, Portla Southworth Machine Maine, a corporation of Original application September No. 698,252, now Patent No.

nd, Maine, assignor to ompa y, Port and,

Maine 20, 1946, Serial 12,542,073, .dated February 20, 11951. Divided-and this application April 9, 1948, Serial No.

September 18,1947

Claims.

This invention relates to printing presses and is most particularly applicable tosheet-fedjlithographic offset presses of the kind described in my copending application for printing press, Serial No. 698,252, filed September 20, 1946, now Pat. No. 2,542,073, dated February 20, 1951, of which this is a division.

The principal objects of this invention are to improve the sheet feeding, transfer and delivery conveyors of the press and their cooperative action. As illustrated in the foregoing machine, sheets are fed successively by feeding mechanism consisting of a first set of grippers which draw the sheet into the 'bight between the offset roll and a main cylinder where the sheet is printed, a second set of grippers which are timed in their relation with the first set so as to grip the'leading edge of the printed sheet simultaneously with release thereof by the first set of grippers to take the printed sheet from the offset roll, and a third set arranged to take the sheets from the second set and to transfer them to a point of delivery. The present invention is concernedprimarily with the construction and operation of the second set of grippers and, as illustrated, they consist of cooperating traveling gripper jaws and means for moving one of the jaws in a helical path into and out of gripping relation with the other jaw.

Further objects of the invention and features of improvement will be apparent from this specification and its drawings wherein the inven tion is explained, by way of example, by the description of a specific mechanism embodying the invention.

In the drawings:

Fig. 1 is a diagram showing the main rolls of the press;

Fig. 2 is a diagram, looking in the same direction as Fig. 1, showing certain of the driving con nections and showing the pile delivery;

Fig. 3 is a vertical sectional.view,looking in the same direction as inFigsl and 2, showing sheetconveying mechanism and mechanism for printing upon (more specifically, numbering) the previously-printed sheets that are carried by the sheet-conveying mechanism;

Fig. 4 is an assembly view showing the side jogger mechanism, paper stop. the chain of the first conveyor means, and the between these parts;

Fig. 5 is a fragmentary view ofithe gripper bar of the first conveyor means,.showing a fragment of the chain of the first conveyor means;

Fig. 6 is a fragmentary vertical sectional view taken on the line 6BofFig. 5; showing the paper interconnections.

.0.9.81- .11 Ca ada stop and mechanism for opening and closing the grippers of the gripper bar of Fig. 5;

'7 is a vertical sectional view taken on the line 'l-. l ofFig. '5 showing one of the grippers of the f rst conveyor means Fig. 8 a yiew similar to Fig. '7 showing the jaw of one of the grippers of Fig. 7 in an open position;

Fig. ;9 is a diagrammatic view taken from the same point of view as Figs. 1. 2 and 3, and on a larger scale, showing the first conveyor means transferring a sheet to the second conveyor .8 1

Fig.1!) is a view similar to Fig. 9 showing the second conveyor means transferring a sheet to the third conveyor means;

Fig. 11 is an assembly view of a portion of the second or'transfer conveyor means, all except one of the several grippers 'being omitted for simplicity of illustration and this gripper being shown in the open position;

Fig. 12 is an end view of the second conveyor means;

Fig. '13 is a vertical sectional view taken generally on the line 13-43 of Fig. 11;

.Fig. 14 is a fragmentary sectional view taken on the line-M-M of Fig. '13 showing a movable jaw of one of the grippers means;

Fig. '15 is a vertical sectional View taken on the line 1 5-f5 of Fig; 14, showingalso' in brokenlines the closedposition of. the gripper jaw;

Fig. 16' is a view taken on the line 3|6'l6 of Fig.3 showingone oi thegripper bars of the third conveyor means;

Fig. 17 is a'fragmentary sectional view taken on the line l 7-41 of Fig. 1'6

Fig. 18 is a fragmentary sectional view taken cn-theline l' 8',l"8 of Fig. 16 showing one of the movable jaws of thegripper 'bar of Fig. 16; and

Fig. 19 is a side elevation, taken from inside the main frame of the press, looking in the same direction as nFies- 1 and showing one side of the dampening mechanism.

of the second conveyor Outline: ofigeneral; organization of machz'ne Serial. No. 590,22,5,' .fi1ed April 25, 1945, .now Pat.

No. 2,519.7,849 dated February 21,. 1950, a continuationeinepart. of application .Serial No.

4 4'90;55'6,'filed'June 12, 1943, now abandoned,

laterally aligned by side jogger mechanism indicated generally at SI in Fig. 4, and are then gripped by gripper fingers 32, Figs. and '7, on a gripper bar 33 carried by chains I00. The course of chains I09 is indicated in Figs. 1, 2 and 3.

The sheet is carried by the traveling gripper bar 33 to and partly around a rubber covered offset cylinder 00, the offset cylinder having a recess adapted to receive the gripper bar.

As shown in Fig. 1 offset cylinder 40 cooperates with a main cylinder indicated generally at 42. Main cylinder 42 comprises opposite end portions I22 mounted on a shaft I66, a lithographic plate holder segment 43 having hub portions 43 also mounted on the shaft I65, and an interchangeable impression segment 44 detachably secured to the opposite end portions 42 Depending upon the character of the work being done, impression segments having surfaces of various materials may be used as more fully'described hereinafter.

As explained in the above patents, a lithographic plate on segment 43 offsets an image onto the offset cylinder 40, the sheet is then carried in between the offset cylinder and the impression segment 04 of the main cylinder, which results in the image being printed from the ofiset cylinder :30 onto the lower surface of the sheet.

The timing and arrangement of the main and offset cylinders and the feeding mechanism, paper stop fingers, side jogger mechanism and gripper bar 33 is such that a sheet to be printed is presented to the nip between the offset and main cylinders at each revolution of the main cylinder, or in other words, at each second revolution of the offset cylinder.

The main cylinder 42 is provided with-plate dampening mechanism indicated generally at 50 and plate-inking mechanism indicated generally at 55 so as first to dampen the water-receptive blank portions of the lithographic plate and then to ink the ink-receptive image-carrying portions during the time that the impression surface 44 is cooperating with the offset cylinder 40. Further rotation of the main cylinder then brings the dampened and inked lithographic plate on segment 43 into position to offset itsinked image onto the rubber surface of the ofiset cylinder 49.

A supplemental roll 00, for instance carrying a rubber plate having raised letters, is arranged to offset onto the otherwise blank surface of-the impression segment 44 of the main cylinder. The image thus transferred to the impression surface id is then printed onto the upper surface of the sheet simultaneously with the printing onto the lower surface of the sheet by offset cylinder 40.

Leaving the nip between the offset cylinder 49 and the impression segment 44, the printed sheet is released by the grippers of bar 33 and simultaneously gripped by a circularly moving second set of grippers 10 (Figs. 3 and 9), which move around axis 1I (Fig. l), and at the end of an approximately 90" circular travel release the sheet and transfer it to third grippers 80 (Figs. 3and 10), which are carried by chains I42 in a generally triangular path, as shown in Figs. 1 and 3.

On the first or downwardly inclined portion of this triangular path away from the offset cylinder, the sheet may be subjected to a further printing operation. Mechanism for such further printing preferably comprises, as shown in Fig. 3, one or more rotating serial numbering units 90 and cooperating platen rolls 9I between which the sheet is carried (Fig. 3) so that the sheet is numbered on its lower surface upon which it had previously received an impression from the offset cylinder.

The chain-carried third grippers 80 then carry the sheet onto the lower horizontal run of their triangular path, in which the grippers are caused to open and drop the sheet, with its ofiset printed and numbered surface uppermost, onto an automatically lowered stack I00 (Fig. 2) on a platform IOI on-which the newly arrived sheet is aligned both longitudinally and transversely by cornerjogging mechanism indicated generally at I20.

The driving connections to many of the main parts of the machine are shown diagrammatically in Fig. 2. An electric motor I is connected by a V-belt I2I to drive a variable-diameter V-pulley I22 .on a counter-shaft I23. A similar variablediameter V-pulley on counter-shaft I23 drives a further V-belt I25 which in turn drives a pulley I23 on counter-shaft I21. Axial adjustment of the pulley sections which comprise the V-pulleys on counter-shaft I23 thus varies the speed of counter-shaft I21 and the further driving connections therefrom.

Counter-shaft l21 is connected by a sprocket I29 and chain I30 to a sprocket I3I on a countershaft I32, which in turn is connected by a pinion Q34 and gear I35 to a shaft I31. At each end, shaft I31 carries sprockets I (Figs. 1 and 3) meshing with and driving chains I42 which carry the third paper grippers 80.

Gear I35 on shaft I31 in turn meshes with a gear I on the shaft 1I, Figs. 1, 2 and 3. Shaft 1I carries a plurality of disks I54 which carry the second grippers 10.

Gear I50 on the second gripper shaft II in turn meshes with a gear I on a shaft I62 which is the shaft on which the offset cylinder 40 is mounted.

Gear I50 on the offset cylinder shaft in turn meshes with and drives a gear I55 which is fast on the shaft I06 of the main drum. Gear I65 also meshes with and drives several other gears which drive various other mechanisms of the press, as subsequently explained.

The offset cylinder shaft I62 carries at its opposite ends sprockets I10, each of which meshes with and drives an endless chain I80, the two chains I carrying the gripper bar 33 on which the gripper fingers 32 are mounted.

The gripper chains I80 at the right end of their path run around sprockets I90, Fig. 3, which are fast on a shaft I9I. Referring to Fig. 4, a gear I92 on shaft I9I meshes with. a gear I93 on a shaft I94 which carries a cam I95. A slidable member I96 which is forked at one end to extend over the shaft I94 carries a cam follower roller I91, with the result of reciprocating this member I96 as the shaft I94 and cam I95 rotate. The upper end of member I96 is also forked to extend over a pinion 201 on a shaft 206, and is provided with a rack section 208 meshing with pinion 201. The paper stop fingers 30 are mounted on shaft 206, and the train of gearing from shaft I9I to shaft 206 is timed so as to retract the paper stops 30 from the leading edge of the sheet at the-moment that the leading dge .of the sheet is ripped by the firstsrinne 32. .A torsion;springtim .onshaftflIi is-adapted to return the shaft .205. pap stop fingers 30 and slidable member I86 to the positions :shown in Fig. 4, as permitted byrotation of the cam el 95.

First conveyor and primers As previously described,.a gripper bar 33 provided with gripperfingers 32is carried by-chains I80 which run on sprockets I110 on the shaft I62 of the ofiset cylinder ,and'on sprockets 190 on the shaft I9 I. The gripper bar 33 isof wedgeshaped cross-section indicated in Figs. ;1 and 6) near its two ends, and outwardly of the wedgeshaped cross-section and asymmetrically therewith isattached to one of thelinks .of each'chain (Fig. .5) so as to follow generally the traveling and .turning movements .of the chain.

The wedge-shapediportions of the gripper bar fit accurately into corresponding -.wedgeshaped openings 300 in a pair of .disksfillll-mountedon the ofiset cylinder shaft I62 .and insimilar corresponding openings in a pair .ofdisks .3IJI .mounted on the shaft I9I. notwithstanding any slight slack which may developin the chains 180, the gripper bar 33 and the .forwardedge of the sheet carried thereby will .always .be accurately registered with the surface-.of the-cflsetcylinder 49. Moreover the gripper bar, through .its engagement with .the wedge-shaped :recesses vin disks 3!", will always occupy :a predetermined position at the instant of retractionof the paper stop fingers 30 and closureof thegripperfingers 32, so that theiorward edges of sheets fed to the gripper bar will occupyapredetermined place on the gripper bar and hence, subsequently, on the offset cylinder 40. Accurate timing of the retraction of the paper stops withrespect to the location'of the gripper harand closure of the gripper fingers is assured by the close mechanical connection (Fig. 4) between shaft I9I which carries the recessed disks 30I land the .shaft 206 which carries the paper .stop fingers 30.

It will be observedfrom the relative positions of the axes of shafts I91, I62 and I66 in Fig. 1 that the line of travel of assheet carried bygripper'bar 33 becomes tangent to .ofiset cylinder 40 and disks 300 a substantial distance ahead of the line intersecting theaxes .of offset cylinder 40 and main cylinder .42, so-that the gripper bar 33 which carries the .sheetis well settledin the Wedge-shaped notches 300 of disks 300 .before the sheet becomes squeezed between the offset cylinder and the impression segment of the main cylinder.

As indicated at Fig. the gripper .bar 33 throughout most of its lengthiscutaway to receive a shaft 304 upon which'the gripper fingers 32 are individually clamped by clamping nuts 394 Coil springs 305 of which one isshown in Fig. 5 yieldingly urge the shaft 304 to-carry the gripper fingers 32 to their closed positions in which their trailing ends enga e with'thelgripper bar.

A small diameter pinion 306 carried at the end of shaft 304 .meshes with an internally toothed rack segment 30! which is .pivotally mounted on the gripper bar-end .at308. Rack segment 30'! is provided with a.crank arm 309 integral therewith,.,carr.ying,acam .follower roller 3H! adapted to engagestationary-camsato.swing the rack and hence turn the pinion.,-306 to hold the gripper fingers temporarily open.

As shown in Figs. .3..and .6 the machineis provided with one such cams III ,partiallysurrounding the shaft I91 this cam-bein iadantedrtonneii th r pp r fin rs. hold them openioran fin stant as the gripper :bar approaches theinejn stop fingers 30, and then allow .theesripnerifin srs quickly to :close upon the fQEWfijIQIfiQEQtOf sheet. .Inliig. 6 the cam iiollower roller 0.21s shown as v.iusthav n dropped. :offircm the :hieb part of the cam -;3 II and allowed th fingered to close. .Also, asindicatedin Fig. 3 .themachine is provided with another such cam 13 $1 5 rounding the shaft 1.62 .of theioffs tzcrlinder. In Fig. 3 the Jgripper :bar is shown at the point pi transfer of the sheet, and the cam :followeiir ller 3 I 0 is about to enga e the .high part pfithergsm 3 I2 to open the gripper fingers.

The construction 40f the mechanism flier con trolling the fingers, comprising the in ion r3116 and the internally .toothedr-racks 1301 an ovidcs a very compact mechanismzcarried'by thegrip er bar and-.capableof imparting :annick opening and closing :movement to the fin ers. s 3113 especially advantageous in ithe closing tot he fingers at the point .of reception of the paper, The gripperbar comesinto pqsitionheneaththe leading edge of the sheet-with itsgripper fingers open to approximately theextent shownin Bi 8, and the-closing movement: of the gripper fins to the position of Fi hamountsato approximately 18.0".

vAs indicated above, in the normal or 41Q1 positionbfthe gripnerfin erscliz they at set to this closed position by theacoil sprin s :35. The resiliency of grip of Y the fin ers Q11 mana er is .furtherincreased by the fact that the fingers themselves are of resilient spring steel and re of :reduced thickness throughout most of their l n th as shown :at 32 in Fig. .7.

,It will .be observed that whereas in in-y prior Patent No. 2,257,490 the chains carrying the pap r t th riest ylinder also carried t p p r away f m th ofis t cy inder andhence needed to :be :provided :with a-plurality .efgripper bars, the press described .herein em lo s chains I which carry the paper no farther than the'ofiset cylinder vandrhence -:reqni re only a single gripper bar. This :feature is 0f considerable advantage since in the ,press described herein each sheet is carried to the -.ofiset;cyli nder by the samelgripper 'bar and there is thus no possibility of any difierencein:registryz of alter-.- nate or successive sheets withtheofiset cylinder.

Second or transfer conveyor and grippers It has been mentioned above that it is desira'ble for the chains I80 that carry-the-gripper bar 33 and first grippers-to carry the paper no farther than the'oifset cylinder and to-carry only a single gripper bar so that-all of the sheets ean be carried to the offset cylinder bythesame set of grippers. It is also an advantageto'deliver the printed sheets in a pile with the side of-the sheet that has received an image from the offset cylinder uppermost.

With these objects in view the machine is provided with a set of secondcrztransfer grippers adapted to transfer the sheet at the offset Y Oyli' inder from the first grippers to a third ordelivery set of grippers. The transfer grippers indicated generally at "70 are respectively mounted upon disk I54 that. are fast on the previously mentioned shaft II, 'Figs. .1 and .11. Fi s, and 9 show the transfer grippers '10 in the act of receiving the sheet .from the first grips pers 32 and Fig. .10 shows the .transferrgrippers as having moved approximately .9.0:.around the shaft H and in the act of delivering the sheet to the delivery grippers 80.

It is an object of the invention to construct the second or transfer grippers so that they can enter into relatively small recesses in the gripper bar 33 as the latter lies in the recess of the offset cylinder. It is, of course, further necessary that this second set of grippers should close quickly upon the forward edges of the sheets presented by the first set of grippers at the point of tangency of the paths of these two sets of grippers. The second set of grippers is accordingly constructed to operate in a different manner from ordinary grippers and more particularly to close upon the sheet by movement about an axis perpendicular to the sheet instead of about an axis parallel to the sheet.

' Each gripper of the second set of grippers is shown as including a bracket 406, Figs. 11, 13 and 15, fastened to one of the disks I54 and including as an integral part a relatively stationary jaw or anvil 401 adapted to engage the sheet. The gripper also includes a movable jaw 4H1 which projects transversely from a rotatable element 4 contained within the bracket 406, the axis of rotation of element 4 and of movable jaw 418 being approximately perpendicular to the paper and its path of travel. Fig. shows the movable gripper jaw 4I0 in full lines in its open position, and in broken lines in its closed position overlying the stationary jaw 401. In its rotation from the open to the closed position the jaw M0 is further given a slight movement in the direction of the axis of the rotatable member 4 to cause it to approach toward the plane of the fixed jaw 401. The combined rotating and axial movement of the movable jaw 4 I 4 thus amounts to a helical movement.

A preferred means for imparting this helical movement includes a helical groove 4I5 developed in the surface of the rotatable member M I, and aholding member in the form of a ball 4I6 positioned in helical groove 4I5 by a threaded pin 4I1. The inner end of the rotatable member 4II of each of the second grippers is provided with a pinion M8 and the several grippers are rotated through their pinions by a rack 420 movable at right angles to the several disks I54. A stationary cam 425 surrounding the shaft 1I engages a cam follower roll 426 on a bell crank 421, the bell crank engaging a collar 428 on the rack 42!] to shift the rack and rotate the grippers. A tension spring 429, connecting the rack to one of the disks I54, yieldingly urges the rack to the left in Fig. 11 in opposition to the action of cam 425, urging the rack to close the gripper aws.

The rack 428 is provided adjacent to its ends with portions 423 of rounded section at each of which the rack is slidably mounted in a sleeve 420 (Fig. 11) which extends through a supporting disk 424 on shaft 1|. A threaded portion 425 carries a stop nut 42$ which may be adjusted to abut against the end of sleeve Hi? to limit the left or jaw-closing movement of rack 420.

In Fig. 9 in which the second grippers 10 have just closed upon the sheet at the offset cylinder, it will be observed that the second gripper jaws 4I0 are enabled to enter into a relatively small recess in the first gripper bar 33 and do not require any enlargement of the opening or gap in the offset cylinder 40 beyond that which receives the first gripper bar.

Simultaneously with the engagement of the sheet by third grippers carried by a delivery chain I42 (Fig. 10) the rack 420 operates to open the second gripper jaws 4I0 and carry them beyond the forward edge of the sheet.

Third or delivery conveyor and grippers As indicated above, the delivery conveyor comprising thechains I42 carries two sets of third grippers, indicated generally at 80 which alternatively receive sheets from the second or transfer grippers 19.

Referring to Figs. 10, 16, 17 and 18 each set of grippers includes a gripper bar I46 attached at opposite ends to pivots of the chains I42, the bar I46 having a central portion I46 of narrow section on which raised portions I46 (Fig. .18) serve as stationary jaws for the plurality of movable gripper jaws. A shaft 44I extending from end to end of the gripper bar and mounted in brackets 442 carries movable jaw members 445 freely rotatable thereon. Each movable jaw member 445 is forked in the region of the shaft 440, and an operating lever 441, fast on shaft 44 I is received between the two branches of each movable jaw member 445. A spring 448 is interposed between the operating lever 441 and a tail piece 445 which is integral with the movable jaw 445, and spring 448 thus connects the operating lever and movable jaw so that rotation of the shaft 44! clockwise in Fig. 18 acts through the lever 441, spring 448 and tail piece 445* to move the jaw 445 yieldingly toward engagement with the stationary jaw I46". Rotation of the shaft 440 counterclockwise causes the operating lever 441 to engage a pin 449 (Fig. 18) secured to the movable jaw member 445 and consequently elevate the jaw positively to an open position.

The shaft 442 is yieldingly urged in clockwise direction as viewed in Fig. 18 by a spring 458, Fig. 16. A crank arm 453 at an end of the shaft 441 carries a cam follower roller 454 adapted to engage a plurality of stationary cams to retain the gripper jaws temporarily open. One such stationary cam is shown in Fig. 3 at 455 surrounding the shaft I31 and adapted to present the third grippers to the second grippers in open condition and then close at the position of Fig. 10. Another such cam is shown in Fig. 3 at 451 located adjacent to the lower horizontal run of chain I42 and adapted to open the third grippers and retain them open a short time while the sheet is being discharged from the third grippers onto a pi e.

The discharge of the sheets from the third grippers, accomplished at the lower run of the generally triangular course of the chains I42, drops the sheets onto the pile with their sides which have received an image from the offset cylinder uppermost.

I claim: v

1. Sheet conveyor mechanism comprising a gripper element for receiving and gripping the leading edge of a sheet delivered thereto at a predetermined place, a support on which said gripper is mounted for movement so as to present said gripper element to said place of sheet delivery, and means for effecting movement of the support, said gripper. element including a pair of sheet gripping jaws, one of said jaws being fixed on the support in a position to have surface contact with the leading edge of the advancing sheet at one side at said predetermined place, the other of said jaws being mounted on the support for movement in two directions relative to the jaw, said shaft having threaded engagement the support for axial movement parallel to a pendicular to the face of the fixed jaw, and rotational movement about its axis, a gear to said shaft, a rack on the support in. mesh said gear, said rack being movable thereon directions to rotate the shaft hence to r the movable jaw to and from the fixed jaw, means normally holding the rack at that extrern-- ity of its movement wherein the jaws are engaged, and cam operated means for effecting movement of the rack in a direction to disengage said jaws, said cam operated means being operable to separate the jaws prior to their movement into said predetermined sheet receiving position.

2. Sheet conveyor mechanism according to claim 1 wherein there is means for adjustably controlling the movement of the rack in its direction for efiecting closing movement of the jaws hence to limit movement of the movable jaw toward the fixed jaw.

3. Sheet conveyor mechanism comprising a plurality of gripper elements distributed at uniform intervals along a common straight line for receiving and gripping the leading edge of a sheet delivered thereto, a common movable support for said gripper elements. means for effecting movement of the support to convey the sheet in an appropriate direction after its leading edge is gripped by said gripping elements and then return them for a succeeding sheet, each gripper element having a pair of sheet gripping jaws, one of said jaws being fixed on the support in a position to be moved into contact with the leading edge of the advancing sheet at a given place, the other of said jaws being movably mounted on the support for movement relative to the fixed jaw, means for effecting angular movement of the movable jaw into registry with the fixed jaw, and concomitantly perpendicular movement toward the sheet engaging face of the fixed jaw, said means including a shaft carrying the movable jaw, said shaft having threaded engagement with the support for axial movement parallel to a perpendicular to the face of the fixed jaw and rotation about its axis, a gear fixed to said shaft, a rack slidably mounted on the support in mesh with the gear of each of the gripper elements, a fixed cam, means operably connecting the rack and cam to effect movement of the rack in a direction to disengage the movable jaw from the fixed jaw, and yieldable means normally operating to move the rack in the opposite direction.

4. Sheet conveyor mechanism comprising a rotatable shaft, means for effecting rotation of the shaft, a plurality of discs spaced along said shaft and rotatable therewith, a gripper fast to each disc close to the perimeter, said gripper including a pair of sheet gripping jaws, one of said jaws being fast to the disc with its sheet engaging face facing outwardly from the periphery of the disc and raised therefrom, and the other of which is movably mounted on the disc and has an inwardly facing sheet engaging surface for registered engagement with the surface of the fixed jaw, said movable jaw being positioned forwardly of the fixed jaw in relation to the direction of rotation of the shaft, being angularly movable rearwardly relative to the fixed jaw to bring it into registry therewith and movable inwardly perpendicularly to the fixed jaw to bring it into engagement therewith, and means for effecting said angular and perpendicular movement of the movable jaw, including a stem to which the movable jaw is fast, said stem having a helical groove therein and being rotatably journaled in a bearing on the support, means in the bearing engaged with the groove permitting rotation of the shaft and effecting axial movement thereof during rotation, a gear fast to said stem, a rack on the support with which the gear is in mesh for effecting rotation thereof, means yieldably urging the rack in one direction to rotate the gear in a direction to effect engagement of the jaws, and means for effecting movement of the rack in the opposite direction to effect disengagement of the jaws.

5. Sheet conveyor mechanism according to claim 4 wherein the discs have registering ways, the rack; is mounted on said ways on said discs for rotation with the shaft but is movable parallel to the axis of the shaft in said ways, the gears of the several grippers meshing with the rack, a cam surrounds the shaft, and a lever is piv otally mounted on the shaft for rotation therewith relative to the cam, said lever having a follower thereon engaged with the cam and being rcckable by rotation of the shaft relative to the cam to effect longitudinal movement of the rack bar in a direction to separate the jaws.

ROY F. ABERLE'.

REFERENCES QETED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 930,097 Sheldon Aug. 3, 1907 1,092,993 Kelly Apr. 14, 1914 1,495,257 Dudley May 27, 1924 1,879,095 Claybourn Sept. 27, 1932 1,920,715 Sager Aug. 1, 1933 1,957,880 Fankboner May 8, 1934 2,024,140 Belluche Dec. 17, 1935 2,025,481 Stussi Dec. 24, 1935 2,063,251 Hertz et a1 Dec. 8, 1936 2,237,877 Fulk Apr. 8, 1941 2,339,310 Wise et a1 Jan. 18, 1944

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