US2723119A - Blank inverting apparatus for printing presses - Google Patents

Description

1955 E. L. ENGEBRETSON ET AL 2,723,119

BLANK INVERTING APPARATUS FOR PRINTING PRESSES Filed Sept. 25, 1950 3 Sheets-Sheet l meg W 31i INVENTORS E url L- Enqebregon Rlckov-d A. HqHeL Rokerl d. HaHeq ATTORNEY Nov. 8, 1955 E. L. ENGEBRETSON ET AL BLANK INVERTING APPARATUS FOR PPPPPPPPPPPPP ES Filed Sept. 25, 1950 i llllllmmmmmlllllnfl IHEQ I26 @A ZLW, I

ATTORNEY Nov. 8, 1955 Filed Sept. 25, 1950 E. L- ENGEBRETSO BLANK INVERTING APPA ATUS FOR PRINTING PRESSES ETAL 3 SheetsSheet 3 INVENTOIG Eur! Enqebreison, k-J-mrd A- HuHeq Robevl" \J. Haueq ATTORNEY United States Patent BLANK INVERTING APPARATUS FOR PRINTING PRESSES Earl L. Engebretson, Richard A. Halley, and Robert J. Halley, Chicago, Ill.

Application September 25, 1950, Serial No.186,'624 12 Claims. (Cl. 271-45)- (Granted under Title, 35, U. S. Code (1952), see. 266) The invention described herein, if patented, may be manufactured and used by or for the Government'for governmental purposes, without the payment to us of any royalty thereon.

The present invention relates, to printing machines, and, more particularly, to a machine for printing in a single operation upon both sides of sheet material or for doing m'u'lti-color work upon one side thereof, and to "mechanism for adapting conventional machines, such as duplicating machines, for performing these operations.

Conventional duplicating machines commonly are of the single couple offset lithographic or of the single couple direct printing type. Due to the demands of the printing processes carried out in these machines, they are capable in a single operation of printing on one side of a sheet only. In the past, therefore, when sheets were to be printed on both sides, it commonly was necessary to print first one side of a sheet and then the other in separate operations. This required the use of two machines or at least changing of the plate cylinder if a single machine was used for this purpose. In either event, there was a duplication of elfort on the part of the operator in twice loading the machine, twice running the material through it, and in twice unloading the machine. At least twice as much of an operators time was therefore occupied in printing. upon both sides of a sheet rather than one, or in doingmulti-color work upon one side of the sheet material rather than monochrome work. In addition, serious problems arose in securing proper registration of the printed material when more than one impression was made on a blank in separate operations. The present invention. is concerned with mechanism for overcoming these disadvantages of the duplicating machines presently 1n use.

Accordingly, an object of the invention is to provide a new and improved printing machine for printing; in a single operation upon the opposite sides of sheet material or upon one side in a plurality of colors.

Another object of the invention is to provide a new. and improved means for automatically and mechanically tinverting flexible material in sheet or blank form.

.A further object of the invention is to provide a new and improved attachment for duplicating machines or like printing machines to adapt these machines for use in. printing on both sides of a sheet or on one side in a plurality of colors in a single operation, and which may readily be adapted to perform either type of operation;

A more specific object of the invention is to provides. new and improved means for inverting fiexible sheet material including a sheet transportingmeans. which reverses thesdire'ction of translatory movement of a sheet incident to inverting the same and means operating/in conjunction with the sheet inverting means for restoring translatory movement to the sheet in the direction it moved its inversion.

A more general object of'the inventionis to provide a new and; improved. device asssetgforth .in the foregoing priorto 2,723,119 Ce Patented Nov. 8, 1955 2 objects which is simple and sturdy in 'constme-tion "and therefore inexpensive to manufacture and install, easy to adjust, and free from liability of frequent breakdown or rapid wear.

These and other objects, advantages and capabilities of the invention will become apparent fromv the following description wherein reference is hadto the accompanying drawings, in which:

Fig. 1 is a diagrammatic view in side elevation of "a pair of printing couples arranged in tandem for printing upon both sides of sheet material or doing multi-co'l'or work on one side and also showing the improved inverting mechanism of the present invention;

Fig. 2 is a view similarto Fig. 1; but'takenon the opposite side of the machine from that on which Fig. l was taken showing the printing couples arranged for doing multi-color work on one side of a blank;

Fig. 3 is a vertical sectional view on an enlarged scale of the improved invertingjmechanism of the present invention;

Fig. 4 is a top plan view of'the improved'inverting mechanism of the present invention; and

Fig. 5 is a fragmentarydiagrammatic top plan view of a portion of the reversing mechanism of the present in.- vention.

in order fully to disclose the construction and operation of the present invention 'andits relationship with a printing mechanism both in an operational and constructional sense, a pair of printing units or couples, indicated as a whole by'thenumbers ltland 12, is diagrammatically shown in Fig. 1, arranged in tandem, with the improved inverting mechanismv indicated in its. entirety by. the .number 14 arranged in operative relationship with these printing couples. In the tworprinting couples. I0 and 12 the operating cylinders are arranged for offset. lithographic printing as carried out in a common form of duplicating machine of the type with. which the present invention is particularly adaptable for use.

Each of the couples shown inFig. 1 includes a plate cylinder 16, a. blanket cylinder 18 andan impression cylinder 20, all rotatably supported by av stationary frame shown in outline at 22 in. Fig. 1. Associated with the plate cylinders '16 is a dampening-mechanism '24 and. an inking mechanism '26. of suitable construction carried upon the frame '22.

Blanks of sheet material such as paper are fed by conventional blank separating and feeding means. (.notshown.) to. a conveyor or feedboard 28 which delivers the blanks to the receiving end of the first couple. The blankseparating. and feeding meansis provided with conventional mechanism for feeding. blanks to .the feedboard28 and conventionally operated stop fingers 130. are provided to release blanks to the operating cylinders. 'These two means. cooperate. to. feed blanks. to the operating cylinders in timedrelation to the cycle of the'first printing couple 10. Blanks printed upon one side (the outwardly facing side). are stripped from. the impression cylinder 20 by a plurality of strippers 32 supported upon. a. bar extending transversely of the couple 10.v A plurality of ejector rollers, one-of whichis shown; at 34, cooperate with an ejector roll 36. to deliver printed. blanks. from :the first couple to the receiving end of the improved. blankinverting mechanism 14.

The various operating mechanisms. above, described, comprising the first printing couple '10,, are driven by a motor '38 (Fig. 2) housed in a base 40 upon which the couple '10 is mounted; This motor is operatively connected to a main-drive shaft 42 (Fig. 2) through abelt M reeved over a pulley on the motor shaftand a pulley 48 on the drive shaft 42-. A second 'pulley' 50' on the latter" shaft has abelt 52 reeved thereoverby means of which the tapes onthe conveyor or feedboard Zli are 3 driven, while a third pulley 54 on the drive shaft 42 drives a shaft 56 through a belt 58 and a pulley 60 on the shaft 56.

The drive means thus far described is set forth by way of example only and may include a pinion 57 (Fig. l) on the shaft 56 meshing with a ring gear 59 on the impression cylinder for driving the latter. In order to effect positive delivery of printed blanks from the first couple 10 a pinion 62 is provided which is driven from the ring gear 59 and drives ejector roll 36 through a suitable pinion 64 on the ejector roll shaft with which the gear 62 meshes. The plate and blanket cylinders 16 and 18, respectively, may be directly driven by suitable gearing from the impression cylinder 20, and other gearing (not shown) may be provided to drive the inking and dampening mechanisms. The mechanism thus far described may be more or less conventional in construction and operation and is disclosed for the purpose of orienting the present invention and disclosing its utility.

Referring to Figs. 3 and 4 it will be seen that the inverting mechanism 14 comprises essentially an endless conveyor including spaced rollers 66 and 68 over which a plurality of conveyor tapes 70 are reeved. Rollers 66 and 68 are rotatably supported in a fixed framework in cluding opposed upwardly inclined lateral frame members 72 of generally rectangular cross-section fixed at their lower ends by welding or the like to angle brackets 74. The lower end of the inverter frame is slotted along the longitudinal axis of the lateral frame member 72 so that this inverter frame may be anchored to the frame 22 of couple 10 by means of shouldered locking screws 76 (Fig. 4). These screws are threaded into the frame 22 of couple 10, and the slotted ends of the inverter frame may be engaged upon the same properly to locate the inverter on frame. The locking screws 76 may be provided with hand knobs at some readily accessible place to facilitate tightening or loosening of the locking screws so that the inverter may readily be removed or replaced. The inverter frame also includes a reinforcing cross-bar or spacer 78 to which the frame members 72 are fixedly secured rigidly to maintain the inverter frame in assembled relation.

The lower roller 66 is rotatably suported upon a fixed axis adjacent the lower end of the inverter framework, while the upper roller 68 is rotatably journaled upon pins 79 carried in bearing plates 80 adjustably secured to the upper ends of lateral frame members 72 so that the tapes 70 may be tensioned or slackened by adjusting the hearing plates 80 longitudinally of the lateral frame members 72. This adjustment may be secured by providing the bearing plates 80 with an elongated slot 82 (Fig. 3) through which pass a pair of anchor screws 84, these latter screws being threaded into the lateral frame members 72. Suitable means are provided on the lower roller 66 to guide the tapes 70, such as snap rings 86 which resiliently grip the periphery of roller 66 so that they may be adjusted longitudinally thereof.

The lower roller 66 is rotated to drive the tapes 70 by means of a pinion 88 (Figs. 3 and 4) rotatably carried by an arm 90 adjustable relative to an angle bracket 92 welded or otherwise suitably fixed to the top side of the right hand lateral frame member 72 (Fig. 4). Arm 90 is fixed to this bracket by means of a pair of screws 94 passing through a slot 96 in the arm and threaded into the angle bracket 92 so that adjustment of the arm and pinion 88 may be obtained in an obvious manner. Pinion 88 is driven by the gear 64 previously mentioned and drives the lower roller 66 through a pinion 98 (Fig. 4) fixed relative to the latter and in mesh with the pinion 88.

As indicated in Fig. 1, the ejector mechanism comprising rollers 34 and roll 36 positively delivers blanks from the delivery end of the first couple 10 to the upper reach of the conveyor tapes 70 in the inverting mechanism 14. A guard 100 is provided on the forward end of the inverting mechanism, this guard comprising a grill which extends around the upper end of the upper roller 68 to the underside thereof (Fig. 3). Guard is supported from the outer end of the lateral frame members 72 by means of plates 102 (Fig. 4) welded or otherwise suitably anchored to the top side of the lateral frame members 72, and supporting blocks 104 removably secured to the plates 102 by means of screws 106. The lateral edges of the guard 100 are received in slots in the sides of the anchor blocks 104 and are held therein by tightening thumb screws 108 against these edges. A sheet-metal plate or tray 110 is provided on the underside of the inverting mechanism 14 and is supported from the lateral frame members 72 by screws threaded into the underside of the lateral frame members. One of these screws is shown at 111 in Fig. 3 and as there indicated springs 112 on the screws bias the forward end of tray 110 away from the lateral frame members. This mounting of the tray permits adjustment thereof toward and from the lower reach of the feed tapes 70.

In order to constrain a blank on the upper reach of the feed tapes 70 for movement around roller 68 to the lower reach of the tapes, there is provided, in addition to the guard 100, two pairs of disc shaped rollers 113 and 114 pivotally mounted respectively upon shafts 115 and 116 between collars 117 fixed on these shafts. The shafts 115 and 116 are suitably mounted adjacent their opposite ends in arms 118, rockably carried at one end of a pair of links 120 which have their opposite ends rockably fixed to mounting blocks 122 rigidly fixed to the underside of the guard 100 adjacent its lateral edges. A pair of tension springs 124 fixed at opposite ends respectively to the arms 113 and the mounting blocks 104 bias the articulate linkage above described upon which the shafts 115 and 116 are mounted in a direction to hold the guide discs 113 and 114 in firm engagement with the periphery of roller 68 on the upper and underside thereof as shown in Fig. 3. Thus, a blank on the upper reach of feed tapes 70 carried forward thereby is guided by the guard 10% and guide discs 113 and 114 around the forward end of the roller 68 to the underside thereof and the lower or return reach of feed tapes 70. Preferably the roller 63 has a friction surface so as positively to move blanks held in contact therewith by guide discs 113 and 114.

It will be apparent that a blank traveling along the lower reach of the tapes 70 will be inverted, i. e., the

printed side will be facing downwardly, and it will be traveling in a direction opposite to the direction in which it was fed to the first couple 10.

Movement of blanks in this direction is assisted by an auxiliary or directional feedboard indicated in its entirety by the number 126. Auxiliary feedboard 126 comprises a pair of rollers 128 rotatable upon axes carried in a frame comprising spaced members 130 (Figs. 3 and 5). This frame is supported at one end only upon a transverse shaft 132 supported at opposite ends in opposed anchor blocks 134. These blocks 134 are adjustably fixed upon supporting rods 136. At one end these rods are supported by opposite plates or brackets 138 fixed adjacent the delivery end of the first couple 10, while at their opposite ends they are supported by posts or bars 140 (Fig. 1) extending upwardly from the base of the second couple 12 adjacent its receiving end. By reason of this mounting of the auxiliary feedboard it may be rocked between the operative position shown in Figs. 1 and 3 and the inoperative position shownin Figs. 2 and 5 for a purpose to be described.

The auxiliary feedboard 126 is provided with a plurality of tapes 142 spaced from each other a distance corresponding substantially to the spacing of the tapes or certain of the tapes in a connecting conveyor or feedboard 144 similar to the feedboard 23 and extending from the delivery end of the first printing couple 10 to the receiving end of the second couple 12. Connecting feedboard 144 is suitably supported at opposite ends upon the opposite brackets 138 and the uprights 140 from which the auxiliary feedboard 126 is supported. Since the auxiliary feedboard 1 26. is supported only at its forward end, the rear end thereof will rest upon the tapes of the connecting conveyor 144 when the auxiliary board is in the operative position shown in Figs. 1 and 3. Suflicient frictional restraint will be generated between the two sets of tapes to cause the tapes on the auxiliary feedboard 126 to be operated when the tapes on the connecting conveyor board 144 are operating. Since the upper reach of the tapes on the connecting conveyor board 144 travel from right to left in Fig. l, the tapes on the upper reach of the auxiliary feedboard 126 will be caused to travel rearwardly or from left to right in Fig. 1.

Preferably, shaft 132 supports the rear end of auxiliary feedboard 126 elevated slightly above the connecting conveyor 144 so that the roller 128 at the rear of this auxiliary board will be maintained elevated slightly above the tapes on the connecting conveyor 144, and thus blanks may pass under this roller undisturbed when the auxiliary feedboard is tilted to the inoperative position shown in Fig. 2.

Since the direction of translatory movement of the blanks is reversed while they are being inverted, it is necessary to provide mechanism for restoring to the blanks the direction of translatory movement which they had prior 'to inversion. Referring to Fig. 1, it will be seen that inverted blanks are delivered by the combined action of the inverting and auxiliary feed tapes to a tray 146 below the impression cylinder 20 in the first couple 10. A plurality of stops 148 upstanding from this tray arrest rearward movement of the inverted blanks. Resilient holddown blank retaining strips 149 are provided to assist in movement of blanks into and out of tray 146.

At intervals synchronized with the cycle of operation of the second couple 12 a shaft 150 rockably mounted in the base of the first couple is rocked counterclockwise with a substantially snap action. This causes a plurality of elongated fingers or kickers 152 fixed thereon and extending through slots 154 in the tray 146 to snap the rear edge of an arrested blank and project the blank forwardly (to the left in Fig. l) with sufficient force to bring the forward edge thereof into engagement with the bite between the tapes on connecting and auxiliary feedboards 144 and 126 respectively.

Shaft 150 is rocked by linkage which may include a bell crank 156 rockable at its intermediate axis upon a fixed shaft 158' and connected at one of its ends to the rockable shaft 150 by means of pivotally inter-connected links 160 and 16 2. Link 162 is fixed on shaft 150, and this shaft is biased in a direction to hold the kickers 152 in inoperative position by a tension spring 163 hooked to an extended end of the pin interconnecting links 160 and 162 and to a clip 165 secured to a suitable fixed part of the frame of the couple 10 as indicated fragmentarily in Fig. 1. Bell crank 156 is rocked by a cam 164 on a camshaft rota-tably driven from the impression cylinder ring gear 5.9 by gearing including a pinion 166 on the camshaft (Fig. 1) and a compound gear 167. The mechanism for rocking shaft 159 obviously is arranged to operate the kickers 152 immediately following each deposit of an inverted blank in the tray 146.

In order that the printed matter appearing on opposite sides of a blank shall register properly the second couple 12 is driven from the first couple 10 in synchronism with the latter by means of a sprocket chain 168 (Fig. 2) or the like. This chain is engaged over a sprocket 170 on the shaft 56 (Fig. 2) in the first couple 1!) and asprocket 172 on the shaft in the second couple 12 corresponding to shaft 56 in the first couple so that the two couples operate together and at uniform speed. Preferably a suitable clutch indicated diagrammatically at 174 in Fig. 2 is provided between sprocket 17.0 and shaft 56 to provide for the adjustment necessary initially to bring the two couples into timed relation or thereafter to bring them into timed relation when the device is changed from two sided to one sided work or vice versa. 7

It will be noted in Fig. 2 that the second eouplelz' is provided with a shaft 176 corresponding to shaft 42 in the first couple 10. This shaft 176 is driven from the shaft upon which sprocket 172 is mounted through gearing (not shown) and has a pulley 178 thereon through which the tapes on connecting conveyor board 144 are driven by means of a belt 180.

Briefly, to describe the operation of the present invention reference will first be had to Fig. 1 which shows the mechanism arranged to print blanks on their opposite sides. Blanks such as sheets of paper are fed by conveyor 28 to the bite of the first couple 10 in timedrelation to the operation of the blanket and impression cylinders 18 and 20 respectively therein so that printed matter registers properly on the outwardly facing side of the blanks passing through this first couple.

As the impression cylinder 20 advances, blanks are stripped therefrom by the strippers 32 and guided by the latter between the ejector rollers 34 and roll 36 which cooperate to deliver the blanks printed side up to the upper reach of the tapes 70 in the inverting mechanism 14. These tapes are driven in the manner previously described in a direction to cause the upper reach thereof to move away from the first couple 10 so that a blank thereon is carried beneath the guard and between the upper roller 68 and the upper and lower guide roller discs 1'13 and 114 respectively which, along with the guard 100,, constrain the blank for movement to the underside of the inverting mechanism onto, auxiliary feedboard 126 whereupon this feedboard directs the blank toward tray 146 where its movement is arrested by stops 148.

It will be apparent that blanks are delivered to the tray 146 inverted, i. e., with their printed sides facing downwardly. Following arrest of movement of a blank in the tray 146 the kickers 152 are rocked counterclockwise by the mechanism previously described and project the inverted blank forward into the bite between connecting conveyor board 144 and auxiliary feedboard 126. Thereupon, the inverted blank is fed by the connecting conveyor board 144 to the receiving end of the second couple 12.

In the event it is desired to do multi-color work on one side of blank material, the lock screws 76 are loosened and the inverting mechanism 14 removed as a unit from the first couple 10. The auxiliary feedboard 126 is then rocked to the position shown in Figs. 2 and 5 clearing its tapes from the tapes on connecting conveyor board 144'. It will be apparent therefore that blanks printed on their upwardly facing side will be delivered by the ejector roll 36 and rollers 34 to the connecting conveyor board 144 printed side up so that they will be printed on this'sa'rne side when they pass through the second couple 12. Thus by using diiferent colored inks in the two couples multi-color work may be done upon blank material in one operation. Delivery of work from the second couple may be elfected by conventional apparatus.

In order to assure passage of the inverted blanks through the second couple 12 properly aligned with the printing cylinders of the latter, a side register jogger (not shown) of conventional construction is provided at the receiving end of the second couple 12. This jogger is operated from the stacker jogger cam shaft of the second couple so that it is always in time with the second couple irrespective of the timing between the first and second couple's.

From the foregoing description of the construction and operation 'of the present invention it should be apparent that a blank invertingmechanism of exceedinglysimple construction has been devised adapting printing units-arranged in tandem for printing on opposite sides of flex-- ible blank material. Furthermore, this mechanism is readily removable so that the printing units may be used for placing a plurality of impressions on one side of a blank as in doing multicolor work. Either type of printing may be done as a single operation thus reducing handling by an operator and reducing the time consumed I by one-half or more.

through the use of substantially the same or equivalent means.

We claim:

l. Mechanism for inverting blanks of flexible sheet material comprising endless conveyor means having reaches moving in different directions, means to guide blanks advanced by said conveyor from one reach thereof to the other so as substantially to invert said blanks and to reverse the direction of translatory movement thereof, means for receiving inverted blanks and arresting translatory movement thereof, a rockable shaft, means for rocking said shaft with a snap action, and a plurality of fingers rocked into striking engagement with the edge of an arrested blank most advanced in the reverse direction of movement in response to rocking movement of said shaft for imparting movement to arrested blanks in a direction corresponding substantially to their direction of movement prior to inversion.

2. Mechanism for inverting blanks of flexible sheet material comprising endless conveyor means having reaches moving in different directions, means to guide blanks advanced by said conveyor from one reach thereof to the other so as substantially to invert said blanks and to reverse the direction of translatory movement thereof, means for receiving inverted blanks and arresting reverse translatory movement thereof, a plurality of fingers mounted for rocking movement into striking engagement with the edge of an arrested blank most advanced in the reverse direction of movement for imparting movement thereto in a direction corresponding substantially to its direction of movement prior to inversion, means to rock said fingers including a bell crank, means including linkage operatively connecting one end of said bell crank and said fingers, and a rotatable cam for rocking said bell crank on its intermediate axis at a predetermined point in the rotation of said cam.

3. Mechanism for inverting flexible sheet m'aterial comprising a rotatably driven roller, means for receiving sheet material and for transporting the same towards said roller, means to guide sheet material over said roller so as to invert the same and to reverse its direction of translatory movement incident to the inversion thereof, a slotted stationary receiver for inverted sheet material, a shaft extending transversely of said receiver and rockably journalled in vertical spaced relation thereto, a

pluralityof fingers fixed upon said shaft and having a free end projecting into the slots in said receiving means, means for rocking said shaft with a snap action in timed relation to the deposit of a sheet in said receiver to cause said fingers to strike the rearwardly facing edge of the deposited sheet and impart motion thereto in a direction corresponding substantially to the direction of translatory movement of said sheet prior to its inversion, and means for receiving the said sheet material from said receiver and transporting the same from said inverter.

4. Mechanism for inverting blanks of flexible sheet 8 material during the course of their movement in a predetermined direction comprising, a single endless conveyor having forward and rear rollers spaced from each other and one or more endless belts trained over said rollers to provide a first reach for receiving and conveying blanks toward the forward roller and a second reach traveling in the opposite direction, means to guide blanks on the first reach around the forward side of said forward roller to said second reach so as to invert said blanks and reverse the direction of translatory movement thereof, means cooperating with said conveyor to continue movement of inverted blanks in a reverse direction beyond said rear roller, means to arrest and receive inverted blanks to the rear of said rear roller, and means to strike the rearwardly facing edge of an arrested blank in timed relation to the arrest of blanks with sufficient force to propel arrested blanks out of said arresting means.

5. In a mechanism for inverting blanks of flexible sheet material the combination comprising, an endless conveyor including a frame, a forward and a rear roller rotatably journaled respectively in opposite ends of said frame and one or more endless tapes drivingly trained over said rollers, means for rotatably driving one of said rollers, a guard including a flat part extending forwardly from a region forward of the rear roller to define an inlet for receiving blanks to be inverted and an arcuate part concentric with the forward side of said forward roller and terminating in an outlet for inverted blanks on the side of said conveyor opposite said inlet, at least two series of idler rollers, rigid members to support the axis of said series of idler rollers adjacent opposite ends thereof so as to maintain said series in parallel spaced relation, links pivotally connected to an intermediate part of said rigid members and to a fixed axis in said inverting mechanism and means yieldably to urge said links and rigid members in a direction to maintain said idler rollers in frictional engagement with the forward side of said forward rollers at circumferentially and axially spaced points.

6. In a mechanism for inverting blanks of flexible sheet material the combination comprising, an endless conveyor including a frame, a forward and a rear roller rotatably journaled respectively in opposite ends of said frame and one or more endless tapes drivingly trained over said rollers, means for rotatably driving one of said rollers, a guard including a flat part extending forwardly from a region forward of the rear roller to define an inlet for receiving blanks to be inverted and an arcuate part concentric with the forward side of said forward roller and terminating in an outlet for inverted blanks on the side of said conveyor opposite said inlet, and means to cooperate with the guard in guiding blanks from the inlet around the forward side of said forward roller to said outlet so as to invert blanks carried by said tapes including a plurality of idler rollers, articulate linkage to mount said idler rollers for free rotation on axes parallel to the axis of said forward roller and rockable around an axis which is movable in a direction to vary the radial spacing thereof from the axis of said forward roller, and means for biasing said linkage to bring said rollers into frictional engagement with the forward side of said forward roller at circumferentially and axially spaced points.

7. In a device for printing upon the opposite sides of blanks of sheet materal the combination comprising, spaced similar first and second printing couples, an endless connecting conveyor for transporting blanks between the delivery end of said first couple and the receiving end of the second couple, an endless conveyor type inverter to receive blanks from said first couple, invert the same and reverse the direction of translatory movement thereof, said inverter having a lower reach spaced upwardly of the connecting conveyor, a third endless conveyor between said connecting and inverting conveyors including an upper reach driven in the same direction as the lower reach of the inverting conveyor so as to assist the latter in moving inverted blanks reversely and a lower reach traveling in the same direction as the upper reach of the connecting conveyor, means to arrest translatory movement of inverted blanks including means to station arrested blanks opposite the bite of said connecting and third conveyor, means for driving said couples, connecting conveyor, inverting and third conveyors in timed relation, and means driven in timed relation to the sequence of said couples positively to propel arrested blanks into the bite of said third and connecting conveyors individually and in a predetermined sequence.

8. A printing device as claimed in claim 7 wherein said drive means includes a single source of power operatively connected to drive one of said couples and means is provided operatively to connect said two couples for simultaneous operation when said one couple is driven including means to vary the timing between the two couples.

9. In a device for printing upon the opposite sides of blanks of sheet material the combination comprising, spaced similar first and second printing couples, an endless connecting conveyor to receive blanks discharged by said first couple and transport the same to the second couple, a unitary blank inverter, means detachably to mount said inverter at a position to intercept blanks discharged by the first couple, said inverter reversing the direction of movement of the blanks incident to inversion thereof, an auxiliary endless conveyor mounted to assume a position intermediate the connecting conveyor and the inverter when the latter is in position in frictional driving engagement with the connecting conveyor and to be swung when the inverter is dismounted to clear the connecting conveyor for directly receiving the blanks discharged by the first couple, means to arrest translatory movement of inverted blanks including means to station arrested blanks opposite the bite of said connecting and auxiliary conveyors, means for driving said couples, conncting conveyor and inverter in timed relation, and means driven in timed relation to the sequence of said couples to propel arrested blanks into the bite said auxiliary and connecting conveyors individually in a predetermined sequence.

10. Mechanism for inverting blanks of flexible sheet material comprising endless conveyor means having reaches moving in difierent directions, means to guide blanks advanced by said conveyor from one reach thereof to the other so as substantially to invert said blanks and to reverse the direction of translatory movement thereof, means for receiving inverted blanks and arresting translatory movement thereof, a rockable shaft, means for rocking said shaft with a snap action, a plurality of fingers rocked into striking engagement with the edge of an arrested blank most advanced in the reverse direction of movement in response to rocking movement of said shaft for imparting movement to arrested blanks in a direction corresponding substantially to their direction of movement prior to inversion and resilient means for guiding the rear edge of inverted sheets into said inverted blank receiving means and lightly to hold the same in position to be struck by said fingers.

11. Mechanism for inverting blanks of flexible sheet material during the course of their movement in a predetermined direction comprising, a single endless conveyor having forward and rear rollers spaced from each other and one or more endless belts trained over said rollers to provide a first reach for receiving and conveying blanks toward the forward roller and a second reach traveling in the opposite direction, means to guide blanks on the first reach around the forward side of said forward roller to said second reach so as to invert said blanks and reverse the direction of translatory movement thereof, an auxiliary endless conveyor cooperating with said inverting conveyor to continue movement of inverted blanks in a reverse direction beyond said rear roller, means to arrest and receive inverted blanks to the rear of said rear roller, and means to strike .the rearwardly facing edge of an arrested blank in timed relation to the arrest of said blanks with sufiicient force to propel arrested blanks out of said arresting means.

12. In a device for printing upon the opposite sides of blanks of sheet material the combination comprising, spaced similar first and second printing couples, an endless connecting conveyor for transporting blanks between the delivery end of said first couple and the receiving end of the second couple, an endless conveyor type inverter to receive blanks from said first couple, invert the same and reverse the direction of translatory movement thereof, said inverter having a lower reach spaced upwardly of the connecting conveyor, a third endless conveyor between said connecting and inverting conveyors in frictional driving engagement with said connecting conveyor including an upper reach driven in the same direction as the lower reach of the inverting conveyor so as to assist the latter in moving inverted blanks reversely and a lower reach traveling in the same direction as the upper reach of the connecting conveyor, means to arrest translatory movement of inverted blanks including means to station arrested blanks opposite the bite of said connecting and third conveyor, means for driving said couples, connecting conveyor, inverting and third conveyors in timed relation, and means driven in timed relation to the sequence of said couples positively to propel arrested blanks into the bite of said third and connecting conveyors individually and in a predetermined sequence.

References Cited in the file of this patent UNITED STATES PATENTS 517,518 Dummer Apr. 3, 1894 961,586 Dexter June 14, 1910 1,149,573 Garner Aug. 10, 1915 1,272,847 Pertz July 16, 1918 1,725,400 Last Aug. 20, 1929 1,836,856 Lloyd Dec. 15, 1931 1,949,001 Albrecht Feb. 27, 1934 2,002,850 Cross May 28, 1935 2,017,191 Whelan Oct. 15, 1935 2,138,995 Belluche Dec. 6, 1938 2,267,784 Belluche Dec. 30, 1941 2,377,525 Schutt June 5, 1945 2,541,752 Eddy et a1. Dec. 13, 1951

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