US2651990A - Sheet controlled rotary printing press - Google Patents

Description

Sept. 15, 1953 c. w. JOHNS ON 2,651,990

SHEET CONTROLLED ROTARY PRINTING PRESS Filed July 15, 1948 5 Sheets-Sheet 1 Sept. 15, 1953 CSWJSJOHNSON 2,651,990

SHEET CONTROLLED ROTARY PRINTING PRESS Filed July 13, 1948 3 Sheets-Sheet 2 y, Maw/A 96 Se t. 15, 1953 c. w. JOHNSON SHEET CONTROLLED ROTARY PRINTING PRESS 3 Sheets-Sheet 3 Filed July 13, 1948 Patented Sept. 15, 1953 2,651,990 SHEET CONTROLLED ROTARY PRINTING PRESS Clyde W. Johnson, Islington, Mass., assignor, by mesne assignments, to A. B. Dick Company, Niles, 111., a corporation of Illinois Application July 13, 1948, Serial No. 38,465

Claims. 1

This invention relates to printing machines and more particularly to printing machines wherein an ink impression is transposed from a lithographic plate to a printing cylinder and then further transposed from the printing cylinder to a sheet of paper.

In lithographic printing the impression or image to be reproduced is placed on a lithographic plate using a greasy ink or crayon. The plate is then chemically treated to fix the impression if such is necessary depending upon the type of ink or crayon used in applying the impression. Printing from this plate is carried out by first moistening it and then applying printing ink Y to it. During the moistening phase the liquid does not adhere to the ink or crayon image, and during the inking phase, the printing ink adheres only to the original ink or crayon impression. The plate is then ready for printing and is impressed upon a printing blanket which retains the ink impression and finally serves to print the impression upon a sheet of paper. This process is analogous to true printing as distinguished from duplicating, multigraphing, mimeographing, etc., because printing ink is applied to the face of the plate, and does not pass through the plate, or come out of the plate itself as in the other processes. Furthermore, this process does not require a special type of paper as the others do.

Conventional printing machines heretofore employed for this type of printing have numerous inconveniences. First, they are bulky. Due to the pressures involved and the centrifugal forces developed when printing at high speed, heavy metal cylinders have been used universally. These cylinders and the heavy metal frames used to support them have rendered the conventional machines inordinately heavy. Secondly, the conventional machine of this type takes up considerable space. Usually the paper sheets go in the front and shoot out at the back into a pan. This necessitates placing the machine in the middle of theworking space, or at least, lengthwise along a wall, and it means that the operator must walk around the machine to obtain test samples. A third undesirable aspect of the conventional machine is the lack of handy control mechanism governing the relative amounts of water (or liquid grease repellent) and ink being applied to the rolls. These relative amounts are usually fixed by permanent design features or can be changed only by laborious adjustment. A fourth disadvantage lies in the use of mechanical trips for the purpose of preventing the press cylinder from contacting the printing cylinder Without a sheet of paper between them. These mechanical trips are not well adapted to respond to extremely fine paper, they involve numerous moving parts, they are noisy and hard to keep in repair. Still another inconvenient aspect of the conventional machine is the mechanism used in attaching the lithographic plate to the plate cylinder. Unlike mimeograph procedure the plate in a lithographic machine must be secured at both ends and drawn tight. In the past this has been accomplished by placing the lithographic plate on hooks and then tightening up by means of screws.

An object of the present invention is to provide a lithographic printing machine which is light, which can be operated in the corner of a room without taking up space, and which can be operated by a person standing in one position. Another object of the invention is to provide convenient ink and moisture controls within reach of the operator in the said position, which controls will allow both quantity adjustment and complete disconnection of either the water or ink from the lithographic plate.

A further object is to provide a simple mechanism for securing the lithographic plate tightly to the plate cylinder Without the necessity for screw adjustments. Still another object of my invention is to provide an extremely sensitive electrically operated trip to detect the presence of paper ready to enter between the printing cylinders. Another object is to provide a control mechanism whereby the pressure of the printing blanket against the lithographic plate can be conveniently regulated or the printing blanket completely disengaged from the lithographic plate.

For purposes of illustration the novel features of this invention are herein shown as embodied in a lithographic printing machine basically similar to that disclosed in my copending application Serial No, 755,065, now U. S. Patent No. 2,590,179. A majority of its cylinders and its side plates are made of aluminum greatly reducing the overall weight of the machine. The ink, moisture and printing blanket cylinders are mounted by use of roller hearings to rotate on eccentric shafts which can be adjusted by hand to disengage their respective cylinders from the lithographic plate cylinder or to regulate their pressures against the lithographic plate cylinder. On the lithographic plate cylinder, I employ a novel clamping device which secures the plate and holds it tightly to the cylinder and which may be operated Without laborious adjustment. I provide an extremely p 3 sensitive micro-switch located in the path of the paper sheet as it approaches the rolls and through its operation, I prevent the pressure cylinder from coming into contact with the printing blanket cylinder in the absence of a sheet of paper between them. In order to return each printed sheet to the front of the machine, a set of gripper jaws is placed behind the bite between the two cylinders and arranged to operate in timed relation with the said cylinders. These jaws engage the leading edge of the sheet and guide it rearwardly for a short distance after which the sheet slides onto a series of conveyor belts which return it to a receptacle at the front of the machine.

An additional feature of my invention is a set of cooperating rolls which engage the sheet prior to its entry into the printing mechanism. These rolls operate in timed relation with the gripper jaws and cause the sheet to pass between the blanket cylinder and pressure cylinder, and enter the gripper jaws just before the instant when the blanket cylinder and pressure cylinder come into contact with each other.

Still another feature of my invention consists in'a prong of novel shape for stripping the sheet from the gripper jaws. It is provided with a protruding belly shaped surface which has the effect of preventing the successive sheets from diving into the forward conveyor, and coming out wrongside up.

These and other objects and features of my invention will best be understood and appreciated from the following description of a preferred embodiment thereof, selected for the purpose of illustration and shown in the accompanying drawings in which:

Fig. 1 is a view in perspective of the entire machine as seen from the front right,

Fig. 2 is a View in cross section of the righthand end of the plate cylinder, shaft and bushings,

Fig. 3 is a view in perspective of the plate cylinder, the blanket cylinder, and the pressure cylinder as seen from the front left with the left side plate broken away,

Fig. 4 is a sectional view in side elevation from the right, thrOugh a plane coinciding with the left ends of the cylinders,

Fig. 5-is a sectional view in side elevation from the right showing the paper stops and the pressure cylinder operating micro-switch,

Fig. 6 is a fragmentary view in perspective showing the micro-switch and its working arm,

Fig. '7 is an exploded view in perspective showing in detail the feed control mechanism as seen from the right front,

Fig. 8 is a view in side elevation showing the paper stop arm and upper feed roll,

Fig. 9 is a view in section from the left showing in detail the gripper mechanism which guides the paper rearwardly from between the cylinders,

Fig. 10 is an enlarged view of the gripper jaws showing them at the top of their forward stroke, and

Fig. 11 is a sectional view of the left hand end of the plate cylinder shaft.

Before going into a description in detail of the preferred embodiment of my invention, a brief survey of its principal parts and their operation will best serve the needs of clarity. A lithographic plate or sheet 30 is wrapped around a cylinder 15 mounted between the main frame side plates 10 and I2. Adjacent and parallel to the cylinder [5 is a cylinder 10 upon which a 4 rubber printing blanket is mounted. These two cylinders are contiguous, are of the same diameter and have intermeshing geared drive as will be explained presently, the point of interest here being that they rotate in unison. Ink and water are applied to the lithographic plate 30 by rolls to be described later, .and'the plate 30 rotates and deposits an ink impression upon the surface of the printing blanket 60. Below the printing cylinder 10 is a pressure cylinder which is mounted for vertical movement in its journals 9| to enable it both to press a sheet of paper against the blanket cylinder and to withdraw from the blanket cylinder when no paper is in between. ln'front of these cylinders is a paper feeding device which employs endless belts Hill to carry successive sheets of paper up to the bite between the cylinder 10 and the pressure cylinder 90. When a sheet of paper reaches position, stops I01 operate to release the sheet and the pressure cylinder 90 automatically rises in exact timing with the blanket cylinder I0. Thereupon the sheet .passes between the blanket cylinder l0 and the pressure cylinder 90 at which time the ink impression on the printing blanket 80 is transposed onto the sheet of paper. The sheet is guided rearwardly by gripper jaws acting in unison with the blanket cylinder 10, and finally, the sheet is dropped and conveyed to th front again by endless belts 1 5| (shown only in Fig. 1).

Proceeding now to a detailed description of the preferred embodiment of the invention as herein shown, the illustrated machine consists in a main frame made principally of aluminum with transversely spaced right and left side plates [0 and 12 respectively, which are connected to each other and held in properly -spaced relationship by tie rods and other parts which are supported in a suitable base indicated generally at M.

An aluminum cylinder 15 is mounted horizontally between the side walls I 0 and I2 upon a fixed shaft is. The cylinder I5 is cut away on one side and provided with a recess 3| into which the ends of a flexible lithographic plate 30 fit as will be described presently. The shaft I8 is held in bushings 20 and-2| which are in turn secured to the side walls Ill and I2. The cylinder 15 rotates freely upon the said shaft It by means of roller bearings l8 located in hubs I! at each end of the cylinder l5. In order to allow free rotation of the cylinder l5'but at the same time preventing it from slipping laterally, the shaft !8 is provided with a flange 22 at its left end and a shoulder 23 near its right end. The distances between the flange 22, the shoulder 23, and the bushings 20 and 2| are accurately machined such that when the bushing 20 is drawn up tight against the shoulder 23 by the lock-nuts l9, and when the flange 22 is lodged in the counterbore 25 provided for it in-the bushing 2|, the distance between the inside walls of the bushings 20 and 2! will be no more than is suflicient to allow free rotation of the cylinder 15.

Inasmuch as the hubs I! are made of aluminum, two steel caps 25 are placed over the hubs IT and present a steel face opposing the inside walls of the bushings-20 and 2|.

At the base of thehub l! in the right end of the cylinder 15 a ear 26 concentric with the cylinder i5 is held between an upstanding flange on an annular sleeve 21 and an annular ring 23. The sleeve 21 is secured to thecylinder 5 by machine screws and the annular-ring 28 is threaded on its inside to screw onto the inner end of the sleeve 27, and when tightened by use of a spanner cular groove.

wrench the annular ring 28 holds the gear 26 rigidly against the flange of the sleeve 21. This latter described mechanism allows the cylinder l5 to be given minor rotational adjustment when it is desired to raise or lower the printed impression upon the printed page.

The lithographic plate 30 is secured to the outer surface of the cylinder I5. As herein shown, the lithographic plate 3!] comprises a sheet of paper prepared to be receptive of an impression formed by the application thereto of ink or other printing material of greasy character. During the printing process the lithographic plate is maintained in a moist condition and printing ink is applied thereto as will be described in detail presently. The moisture which is applied first does not adhere to the greasy ink impression and conversely when the printing ink is applied it only adheres to the greasy ink impression. Thereafter the ink impression is transferred to the printing blanket so and printed upon the paper sheet as will also be described presently.

The mechanism for securing the lithographic plate 39 to the cylinder l5 will now be described. A flat bar 33 is secured to the cylinder |5 by screws and located in the recess 3| within the radius of the said cylinder. A shaft 34 passing through journals in the ends of the plate cylinder i5 is located under the fiat bar 33 and parallel to it. The shaft 34 is provided with upstanding lugs 35 which are located to touch the bar 33 when the shaft 34 is rotated. At each end of the shaft 34, helical springs 36 are provided which hold the lugs 35 in restrained relation against the flat bar 33. A thumb lever 31 is provided at the left end of the shaft 34 for the purpose of rotating the said shaft and thereby allowing the lithographic plate 33 to be inserted between the fiat bar 33 and the lugs 35. A peep hole 38 is provided in the flat bar 33 for the purpose of observing whether or not the lithographic plate 30 is fully seated.

After insertion under the bar 33, the lithographic plate 38 is wrapped around the cylinder |'5 until it meets a second flat bar 4|] disposed parallel to the flat bar 33 and which has inwardly extending arms 4| pivotally connected near the core of the cylinder |5. The fiat bar 40 is likewise located within the recess 3| and at no time does it project outside of the circumference of the cylinder l5. A shaft 42 similar to the shaft 34 is mounted parallel to the bar 40 and likewise carries lugs shown only at 43 in Fig. 4. The shaft 42 is also provided with springs (not shown) similar to the springs 36 and which rotate the shaft 42 such that the lugs 43 are urged always against the bar 43. Two tension springs 44 are secured at one end to the cylinder |5 at the base of the flat bar 33 and at the other end of the springs to the arms 4| of the bar 40. These latter springs tend to swing the bar 40 towards the bar 33.

At the left end of the shaft 42 a control lever 45 is provided for the purpose of rotating the shaft 42 to disengage the lugs 43 from the bar 40. The control lever 46 is provided with a slanting end and a circular groove set back from the end. Directly facing the slanting end is a steel pin 41 located so that the slanting end of the control lever will engage it. Thus when the fiat bar 40 is rocked toward the pin 41 the control lever 46 is raised by the'pin 41, the shaft 42 is rotated, the lugs 43 separate from the under surface of the flat bar 4|] and the control lever 46 locks with the pin 4'! by means of the above mentioned cir- In this position the lithographic plate 30 is inserted between the lugs 43 and the flat bar 40. Thereafter the final clamping step merely involves pulling the bar 40 toward the bar 33. The control lever 46 then disengages from the pin 41 and the lugs 43 snap up against the lithographic plate 30 holding it firmly against the bar 43. 'I'hereupon the springs 44 acting to pull the bar 4|] toward the bar 33 pull the lithographic plate tightly around cylinder l5.

Above the cylinder I5 is the moisture applying apparatus. It comprises a frame including aluminum side plates 50 and 5| maintained in spaced relationship by suitable tie rods. The side plates 50 and 5| are secured to the upper edge of the side plates I0 and I2 and render the moisture applying apparatus detachable as a complete unit.

A tubular flask 52 containing water or other grease repellant liquid is supported horizontally across th top of the frame by braces 53 which are in turn connected to the side plates 50 and '5 The liquid is then fed into a trough (not shown) from which it is picked up by a metal cylinder 54, which has a knurled surface that is wetted by the liquid. The liquid is then transferred to an intermediate spreading cylinder 55 which presents a felt or similar fabric surface, thence to another similar cylinder 56 and finally to the moisture applying or molleton cylinder 51. The cylinder 51 which is at all times parallel to cylinder I5 is mounted for free rotation upon an eccentric shaft 58 by roller bearings (not shown) similar to those used in connection with the cylinder |5 (Fig. 2), and is driven by a gear 60 which is secured to its right end and which intermeshes with the gear 26 of the cylinder IS. The shaft 58 is eccentric by being oifset uniformly at each end of the cylinder '51, but it is to be understood that the cylinder 51 rotates uniformly about its own axis. A hand knob 6| is provided at the left hand end of the shaft 58 and when it is used to turn the shaft 58, it operates through the eccentricity of the shaft 58 to bring the cylinder 51 into contact with the lithographic plate 30. By this knob 6| greater or less pressure between the cylinders l5 and 5! can likewise be regulated.

The cylinder 56 is disposed parallel to the molleton cylinder 51 and touches it at all times thereby being rotated by the friction between them. In order to account for change of position of the molleton cylinder 51 however, the cylinder 56 is mounted to slide in vertical channels 63. The other cylinders 55 and 54 are likewise contiguous in succession and are mounted in suitable bearings in the side plates 50 and 5|.

The printing ink applying apparatus will not be completely described inasmuch as it comprises conventional spreading rolls and a final applying roll which rotates in unison with the cylinder I5. It is of note however that the ink applying apparatus is mounted upon a frame which is provided with an eccentric shaft of the same shape as the shaft 58. This latter shaft can be rotated to allow either a complete disengaging of the ink applying roll from the cylinder IE, or varying degrees of pressure between the cylinder l5 and the ink applying roll.

Proceeding now to the printing apparatus, it consists in the cylinder 10 which lies below and parallel to the cylinder l5. The cylinder 10 is recessed on one side at II. It is mounted by means of roller hearings to rotate freely upon a shaft 12 (see Fig. 4). The shaft 12 is ofiset at each end of the cylinder 10 rendering it eccentric and by use of a hand lever I3, serves to move the cylinder 10 into contact with the cylinder l5 and inder 90 away from the "blanket cylinder .10.

plate cylinder I5.

also to: regulatethe,pressure betweenzthe twosaid cylinders. Itisto ibenotedzthat the cylinder-10, aswell as the roll.58, rotateifreely .uponthe shafts which support them, and :eccentricity of the shafts becomes eifective only whenwthe *sidecontrols are turned.

The cylinder '10.-is drivemby. meansaof a gear 14 which is secured to the end of thescylinder 10 by screws and which :intermeshes with .thezgear Incidentally, although the turning f .the eccentric shaft 12 ;disengages-thecylinder 10. from contact with the cylinder-I5, it -.does-not.totally separate the gear teeth. This:islikewisetrue of the other gears .above described which .are mounted on eccentric shafts.

In order to allowifreeerotationofthe-cylinder but at thesame time to preventiit from:slip ping laterally .on :theshaft -12, .cams 1-5, which serve: an additional: purpose to:be: explained presently, are secured 1 to the shaft 1-2 by :taper pins and are located in suchzposition on thesaid'shaft that .their inner walls are :exactly far enough apart to allow cylinder 10 to rotate freely butnot to'slide horizontally. Ascrew'ifi is threaded into the left hand end of ithe shaft 12zandrserves to hold the lever 13 in;place vupcn'thesquared end of the shaft 12. The-right hand-end of the shaft 12 then fits freely in aabushing 1'8" (see-Fig. .1 outside), the lateralplay of -the'shaft beingtaken care of .by thecams 15-:fitting snugly between the shaft bushings on each: end.

A sheet of porousor -resilient material conveniently termed a printing blanket 80. is. secured to the face of the .cylinder'1'0 being hookedwithin the recess 1I ationetof. its edges. wrapped-around the cylinder face, vand-hooked.a'gain at its other edgewithin' the recess 1| by the'hookszm. .-On one side of the recess 1|, "the hooks .0! are mounted on the cylinder;10, but .on the otherside of the recess 1i they. are mounted ongatransverse bar82-whieh is held in: position anddrawn'toward the center of the cylinder 10 to-tightenithe blanket 00 by the screws --83 which aresconveniently threaded to the core oftheacylinder 1-0.

Directly beneath the blanketscylinder .1 0 ,a steel pressure cylinder 00 ismounted parallel to :the blanket cylinder 10,.injournals 9| which .are arranged to slide vertically in 'guides'02. .A.comression spring .93 is located.under eachsjournal .9I and tends to pressthe cylinderz00 .up-iagainst the blanket cylinder '10. The pressure of the springs-03 is adjustably controlled .by set "screw .04. A flat hardenedmlate v95is5secured to'the top of each journal QI-by screws and; cooperating with the cams 15, serves to hold'thetpressure. cyl- .It is to be noted, however, that the camsllifonly engage the plates 95and depress the-pressure cylinder 90 at times when .the shaft 12:is rotated by means of the hand lever" for the purpose of disengaging the :blanket cylinder 10 :from the Thejjournals 9| are each .provided with a.notch.intheir-forward wallsifor the purpose of holding the cylinder-90 in-the lowered position as will be explained presently.

In addition to the cams 1.5, thereis another .pair of cams BB-Which-depress thecylinder 90 against the compression of-theesprings' 93. latter mentioned pair of cams:9.6 are mounted on This the ends of the-cylinder .10 andsecured to it by screws. lUnlike thecamslfi whichforce the jourpress the :pressure cylinder flllduring .the partof the cycle of the blanketcylinder when the recess 11 ,passes-the pressure cy1inder90.

' Thepressurecylinder 90 is driven in rotation by-a. ear 91 which issilver solderedtoit and the teeth of which intermesh in-the teethofthegear 14. Although the .gears 91 and 14 move sufficiently apart to (allow their respective cylinders to.-separate,- this movement is not enough to disengage the gear teeth.

Theapparatus for feeding the paper into the machine -will:now bedescribed. It comprises a series of endless belts I00 mounted on suitable rollers and driven by. a belt (not shown) suitably connected to the source ofpower. The belts I00 approach the machine at a slight angle, approximately-Sf, for the'purpose of continuously aligning the successive sheets of paper against the guides IN. A conventional frictionfeeder (not shown) driven .bythe belts I00 may be used to placesuccessive sheets of paper on the belts I00. Proceeding over the belts I00,.the sheet of paper slides betweena lower plate I02 and an upper platel03 which lie-one-on top of the other and arersecured in a horizontal position to the main frame. The plates I02 and I03 are dished to provide space betweenthem for the paper to pass, and spread at their forward edges to provide a funnel shaped entrance forthe successive sheets. The upper plate I03 is provided with a series of transversely disposed-holes for the purposes of permitting the entrance of air, and also to lighten the assembly. Thelower plate I02 extends considerably more towards the rear than'does the upperplate I00, the lower plates rear edge being adjacent to .the bite between the pressure cylinder .90 and the blanket cylinder 10. Midway in the lower plate I02 and to the rear of the upper plate 03, a slot I04 is provided to permit a paper feed roll 05 to extend, upwardly through the said lowerplate I02. Further towards the rear of the lower plate I02, transversely spaced holes I06 are provided to allow stop lugs I01 .to pass upwardly through the lower plate I02, and arrest the passage .of the paper when such is desired. A retainer plate I 08 is secured to the lever plate I02 betweenthe slot I04 and the holes I08 to prevent the paperfrom accidentally hopping over the stop lugs- I01. This function of ,the' retainer plate I08 isaided by notches in'its rear edge which correspond to the holes I00 and allow it to extend somewhat around the stop lugs I01 when they are in the raised position. The forward edge of the retainer-plate I03 is bent upwardly to aid in .guiding the paper between it and the lower plate 1.02. This can be seen in side elevation in Fig. 5.

The paper feed roll I05 is*mounted horizontally in suitable bearings secured to the main .framaand lies parallel to the pressure cylinder '90. The feed roll I05 is provided with a chain drive H0 which is driven in turn by a sprocket (not shown).

The stop lugs I01 are mounted on a cross bar I I I-which inturnis secured to sideblocks I I2 (on 'ea'chend) which are pivotally mounted on pins I I4. The pins IiI'A are secured to the main frame. Twocompression-springs H5 (see Fig. 8) between flanges 5H6 depending from a transverse tie rod H1, and depending ears II3 :of the side blocks 'I'I2tend to ;pivot .the stop lugs I01 upwardly at all times.

An 'upper paper feed roll II 8, mounted horizontally, parallel to, and cooperating with the .feed .roll I05 is supported laterally by journals I20 yvhichslide vertically .in guides I2I. The

guides I2I are silver soldered to the side blocks H2. The upper roll II8 does not touch the feed roll I05 when the side blocks I I2 are pivoted upward so as to project the stop lugs I01 through the holes I06 in the lower plate I02, with the result that there is no compression on a sheet of paper stopped by the lugs I01 and the feed roll I05 merely rotates, sliding under the sheet. But when the stop lugs I01 are lowered to release the sheet, the upper feed roll H8 is lowered simul taneously, engages the sheet, and presses it against the feed roll I05. When this happens, the sheet is caught between the two feed rolls and propelled into the machine.

When the upper feed roll I I8 engages the lower feed roll I05, the journals I slide up the guides I2I and compress a spring I24 held against the journals I20 by cross heads I25. This assures a relatively even feed roll pressure for different thicknesses of paper and renders fine adjustments unnecessary.

An arm I22 extends rearwardly from the left hand side block I I2 and serves the-purpose of pivoting the blocks I I 2 and their connected members. The arm I22 engages a. cam I 23 which is secured to the blanket cylinder 10, and depresses the arm I22 and blocks H2, once each cycle of the blanket cylinder. The cam I 23 is cut and positioned to depress the arm I22 and cause the paper to be released while the blanket cylinder recess II is facing the pressure cylinder 90. More will be said presently about the precise timing of the cam I23 with respect to other cams and to the feeding and printing operations.

When the leading edge of the paper has passed between the cylinders 10 and 00 it is grabbed by gripper jaws which are similar to those described in my copending application serial No. 155,065 and shown in that application in Fig. 5. As shown herein, referring to Fig. 10, they are sup ported on carriers I 26 slidably mounted on shafts I21 connected to the inner face of the side plates I0 and I2, parallel to the said plates and slanting downwardly towards the rear. Each carrier I26 is reciprocated up and down its respective shafts I21 by lever arms I28 which are pivotally connected one to each side wall by pins I30 (see Fig. 9). The arms I28 connect to the carriers I26 by means of pins I3I which slide in appropriately formed slots in the upper end of the arms I20, during the stroke. The arms I28 are in turn reciprocated by action of links I32 connecting to slides I33 mounted in guides I34. The slides I33 are driven by side face cams I35 shown in dotted lines in Fig. 9.

The gripper jaws themselves comprise four jaw pieces I4I shown only in Fig. 10, evenly spaced along a cross bar I31 which passes horizontally across the machine and joins the two carriers I26. A shaft I38, mounted for rotation in the carriers I26 adjacent to and rearwardly from the cross bar I31, likewise passes across the machine between the carriers I26. The shaft I30 at each end mounts an arm I which serves to rotate the shaft I38 as will be explained. Along the shaft I 38 the jaw pieces I4I are secured to the shaft I38. Each jaw piece MI is provided with a spring I42 which presses against the cross bar I31 and tends to rotate the shaft I38, holding the lower jaws MI in restrained relation against the forward edge I36 of the cross bar I31. The cross bar I31 is provided with slots I39 into which fits an upstanding flange I49 connected to the jaw pieces MI. The flange I49 serves as a stop for the leading edge of the paper,

The arms I40 serve the function of opening and closing the gripper jaws at the proper time and for this purpose each are provided with a pin I43 which is acted upon by fixed cams I44 and a rocker plate I45, there being but one rocker plate located on the inside of the side plate I0. At the end of the back stroke, the pins I43 ride up on the cams I44, causing the arms I40 to rise thereby pivoting the jaws open. Then as the carriers I 26 start on the forward stroke, the arms I40 leave the cams I44, drop down and the jaws close momentarily but soon the pin I43 on the right hand arm I43 engages a flange I46 on the rocker plate I45 and commences to rise again. The rocker plate I45 is held with its rear edge tilted downward by a spring I41. Thus on the forward stroke, the pin I43 rides up on the flanges I46. Only one rocker plate is necessary because on the forward stroke, there is little tension or other cause for misalignment of the carriers I26. As the carriers I26 near the end of the forward stroke, the arm I40 will have been elevated and the jaws will be fully open. Also during the forward stroke, the rocker plate I45 tilts forward as the weight of the pin I43 passes the pivot point of the said rocker plate, and compresses the spring I41. Just before the end of the forward stroke, the pin I43 passes the forward end of the flange I46 and allows the arm I40 to drop and, consequently, the jaws to close. The jaws then remain closed until the end of the back stroke. It can readily be seen that this mechanism will not oppose a reversing movement of the rolls, a feature of importance when it becomes necessary to clean the rolls or for other reasons to reverse the rotation of the cylinders. Such a reversing action was not feasible with the mechanism of my copending application Serial No. 755,065, now U. S. Patent No. 2,590,179.

The paper is taken out of the gripper jaws at the bottom of the back stroke by a series of prongs or stripper fingers I48 which are supported by a cross bar I50. At this point, the paper passes downward onto a conveyor which first draws the leading edge of the paper rearwardly and then, when the paper is fully separated from the printing cylinders, conveys it into a pan in front of the machine by means of belts I5I (see Fig. 1). The apparatus for conveying the paper forward is fully described in my copending application above mentioned, and therefore, has been omitted here.

It is of importance, however, to prevent the leading edge of the paper from diving after it leaves the gripper jaws because if it does dive, it may enter the forward conveyor improperly and come out upside down. To take care of this, prongs I48 must be carefully designed. A straight slanting surface does not achieve the desired result, but rather it must be given a decided belly. If this is done, the leading edge is at first caused to buckle slightly and then in springing back, to follow around in conformance with the lower contours of the prongs I48.

The mechanism for holding the pressure cylinder in the lowered position will now be described (see Fig. 4). It consists in two pawls I52 pivotally mounted on a shaft I53 which is in turn mounted in suitable journals secured to one of the main frame tie rods. The pawls I52 stand upright and are adjacent to the forward Wall of each journal Ill. The pawls I52 are provided with a hook shaped end whichv engages the above mentioned notch in the forward wall of each of the journals 9|, the said notches being so located as to receive the pawls I52 when the pressure cylinder 90 is in the lowered position whether depressed by the cams 15 or the cams 96. The pawls I52 thereafter hold the pressure cylinder 96 down until they are withdrawn from the notches. The pawls I52, being mounted on the shaft I53, swing in unison. They are controlled at the left side of the machine by a tension spring I54 and a solenoid I55. The tension spring I54 connects between a link I 56 and the main frame. The link I56 is connected to the left hand pawl arm I52 and since the spring I55 tends to draw the link I56 rearwardly, it likewise swings the pawls I52 rearwardly holding them pressed against the journals 9| and ready to enter the notches when the said journals are lowered. The link I56 at its forward end is connected to a solenoid I55; which is controlled by a micro-switch I51. The solenoid I55 draws the link I56 forward against the tension of the spring I54, and in turn the pawls I52 arethereby swung forward. Since it is desirableto utilize the full stroke of the solenoid, a slotis provided in the link I55 to permit the full stroke to be taken without moving the pawl arms the entire dis tance. As shown in Fig. 4, the solenoid I55 'is at the full extent of its" forward stroke.

The solenoid I55 only acts to draw the pawls I52 forward when there is a sheetof'paper present on the feed roll I55. Theabsence of a sheet is detected by a working arm I58 of the microswitch I51. The working arms I58'is formed in the shape of a horse shoe, pivoted centrally and fitted with clearance into a circumferential groove I59 in the feed roll I55, its upper end lying in the path of the paper and its lower end controlling the micro-switch I51. In order to prevent the upper feed roll I I8 from tripping the micro-switch I51, a similar and opposed groove I! is likewise provided in the said'upper roll I I6. When a piece of paper enters between the feed rolls I 65 and. N3, the workingarm I58 is depressed until its upper surface is flush with the top surface of the feed roll I05 in which position it trips the micro-switch I51.

The machine is driven by any suitable source of power turning a sprocket I60 located on the right hand side of themachine. Hand power can be usedwhen the machine is not in operation to turn this sprocket when it is desired to rotate the cylinders small amounts forward or backward. The sprocket. I60 serves to drive the feed and return belts by means of an endless belt I6I. It also turns a shaft I62 upon which it is mounted, and drives an endless chain I63. The chain I63 serves to turn a shaft I64. The shafts I62 and I64 mounted in suitable bearings pass through the side plate I0 anddriven pinions I65 and I66 respectively (see. Fig. 9). The pinion I65 drives a gear I61 upon which the cam I35 is mounted. The gear I61'is mounted upon a shaft (not shown) which also serves to drive the endless chain IIii by means of a sprocket (not shown). Finally, the pinion I66, intermeshing with the gear 26, serves to rotate the plate cylin der I5, and thereby rotates the cylinders associated therewith as above described.

The operation of my invention will now be described paying particular attention to the positioning of the cams and their precise timing relationship to the various cylinders in the cycle of the machine. Let us start with the lithographic plate 30 already mounted on the cylinder I 5, the moistening and ink rolls engaged, the blanket cylinder 80 in contact with the plate 30, the cylinder 90 held in the loweredposition by the pawls I52, and with the power on; All of'the cylinders will be rotating and the feed and return belts will be in motion. However; since'no paper has as yet been introduced; the arm- I58 of themicroswitch I5T will not have been depressed with the result that the solenoid: I55 will not withdraw the pawls I52 and the pressure cylinder 90 will remain-in the lowered position. Before introducing a sheet of" paper let' us examine the activity of'the various cams. The earns 96 at each end of the blanket cylinder-10 will be rotating with each rotation of the'blanket'cylinder 10 and depressingtherings 98 of the pressure cylinder 90 each time the recess1l passes the cylinder 95. But since the solenoidjl 55- isnot being energized, the-pressure cylinder lfl'remains held in its lower position by the pawls I52. The cam I32 on the left end. of'the, blanket cylinder 15 depresses the arm I22 oncerduringeach cycle and consequently the upper-feed-ro'll. IIB andv the stop lugsiI01 are reciprocating up and down. Behind the pressure cylinder-9.0; the. gripperjawstare: also reciprocating, being driven." by action of. the cams I35. Once duringeaclrcycle, as'the. recess 1I commences to passzthe cylinder 90; the gripper jaws come forward? and. venterythe-r said' recess mo.- mentarily at the'top ofltheir stroke, and then recede: before: theleadingredge: 'of the; blanket comes. around.

Now let usintroduce-1a: sheet of' paper. It is placed upon. th'BfbBltS'IUfl and carried between the plates I 52' and" lfflflfover'the'feed roll I05 and up" against they stoplugs. I01. The microswitch I51 is:tripped'and 'tlreisolenoid I55 draws the pawls. I52 forward. It:should be'mentioned here thatthe upward compression of the springs 93 against the journals 9i isstrong enough to preventthesolenoid; I55' from withdrawing the pawls I52'wherr'the'cylinder: is free. Thus the said pawls will' notberwithdrawn until the cams 96 come around and. relieve this compression, even though a sheet .of papais'present.

The-cams 9.6 are: located to: depress the pressurecylinder justafte-r the. trailing edge of the blankettfl. passes. the. pressure cylinder 90 in. rotation. .At. this. point. the clear sheet will still be held in check bythe stop lugs I01, but within a few degrees of;.rotation, the cam I23 depresses thearm. lg22 withdrawing the stop lugs and l 'the upper feed roll H8. The sheet, now gripped between the two feed rolls is propelled into the machine. It will be noted at this time that the gripper jaws are entering the recess and there is. space between the cylinders 90 and 10. The grippenjaws remain open until the last instant before the top. of their stroke as above. described; and the feed rolls propel theleading edge ofthe sheet into them while they are. still. open. Forthis latter purpose, the rotational velocity ofv the feed roll I05 must be carefully adiustedto assure entry of the leading. edge of the sheet into the jaws but to avoid buckling of the paper. The cams 96 then allow the pressure cylinder. 90 to rise, the pawls I52 having been withdrawn, the gripper jaws withdraw, and the. sheet is. pressed between the blanket 80 andthe cylinder 90.

Thereafter, the sheet of paper passes. on through, receiving the ink. impression, the cam I23 allows the arm. I22 to ris.e,.disengaging the upper feed roll H8 and bringing up the stop lugs I01. If another sheet is not introduced, the cams 96 depress the cylinder 90 after the trailing edge of the blanket 80' passes, and since the solenoid I51 will not be energized, the pawls 13 I52 will then enter the notches in the journals 91 holding the cylinder 90 in the lowered position.

If it is desired further to prevent the pawls I52 from disengaging the journals 9!, the microswitch working arm I58 can be adjusted not to respond to the weight of the paper but only to be depressed by virtue of the upper feed roll H8 pressing downward upon the paper to each side of the said working arm.

While numerous minor variations will be readily apparent to those skilled in the art, it is to be understood that the invention is not limited to the precise embodiment herein shown, but s rather to be measured by the scope of the following claims.

Having thus disclosed my invention and described in detail a preferred embodiment thereof, I claim as new and desire to secure by Letters Patent of the United States: v.'

1. In a printing machine wherein a sheet of paper is pressed between two printing cylinders one of which carries a resilient blanket and serves the purpose of transposing an ink impression to the paper, the other having a smooth surface and serving the purpose of pressing the sheet against the blanket, means for feeding successive sheets of paper into the front of the machine, means for returning successive printed sheets to the front of the machine with printed sides uppermost, comprising carriers mounted for reciprocal movement in the direction toward and away from the rear of the printing cylinders gripper jaws mounted on the carrier for movement therewith and including means forming a part of the gripper jaws to render same effective to grip the leading edge of each sh et as it emerges from between the printing cylinders and leading it rearwardly and release the leading edge of the sheet near the end of the rearward stroke, fixed stripper fingers positioned alongside the grippers to engage the leading edge of the pap for removing same from the gripper jaws when open, a forwardly moving endless belt beneath the gripper jaws when in the rearward end of their stroke for conveying sheets deposited therefrom to the front of the machine, and means forming a part of the stripper fingers to buckle the paper upon engagement and guide same onto the belt.

2. A printing machine as described in claim 1 further characterized by stripper fingers having a profile contour as follows: first slanting rearward and downward, then bending around and presenting a forward slant while still continuing downward, and then bending back and finally slanting rearward and downward again, the said contour being so constructed and arranged as to dislodge the leading edge of a sheet from the gripper jaws, start it downward, buckle it slightly and then as it slips down, allow it to spring back thereby remaining in the horizontal position without being inverted.

3. A printing machine as described in claim 2 further characterized by springs holding the printing cylinders in pressure applying relation against each other, and the solenoid action not being sufficiently strong to withdraw the pawls unless the compression of the said springs against the said pawls is relieved by the said cams.

4. A printing machine wherein a sheet of paper is pressed between two rotating cylinders, one of which transposes ink to the paper, having in combination means for separating the cylinders momentarily once during each cycle of the ma- '14 chine, and a feeding mechanism carrying suc cessive sheets of paper from the front of the machine to the bite between the cylinders, comprising the following members, viz, belts conveying the sheet, stops arresting the progress of the sheet at a point adjacent to the bite between the cylinders, a lower feed roll mounted for axial rotation in fixed bearing adjacent to the said stops, the said lower feed roll supporting the sheet when the latter is arrested by the stops, an upper feed roll mounted for movement towards the lower feed roll and mounted in bearings for free rotation, a pivotally mounted fram supporting both the stops and the upper feed roll, and a cam operatively associated with the printing cylinder for simultaneously causing the said stops to be released and the said upper feed roll to press the sheet against the lower feed roll for feeding the sheet into the space between the printing cylinders, means for guiding successive sheets rearwardly after the printing operation, comprising gripper jaws mounted for reciprocation from the rear of the machine into the space between the printing cylinders when they are separated, a cam for opening the jaws at the rear end of their travel and closing them at the forward end, means for rotating the lower feed roll at such a velocity as to place the leading edge of the sheet in the gripper jaws before the gripper jaws close and commence their rearward motion, means for stripping the sheet from the gripping jaws after they have completed their rearward stroke, and belts conveying the sheet to the front of the machine.

5. In a printing machine wherein a sheet of paper is pressed between two printing cylinders one of which carries resilient blanket and serves the purpose of transposing an ink impression to the paper, and the other cylinder has a smooth surface and serves the purpose of pressing the sheet against the blanket, cams separating the cylinders momentarily once during each cycle of operation, and mechanism for feeding the sheet into the bite between cylinders, guiding it at first rearwardly and then guiding it to the front of the machine, comprising a lower feed roll for guiding the paper up to the bite between the cylinders, stops arresting the progress of each sheet as it reaches a position adjacent to said bite, an upper feed roll operatively associated with the lower feed roll, a cam for simultaneously withdrawing said stops and lowering the upper feed roll to press the sheet against the lower feed roll at a time when the two printing cylinders are in separated position, reciprocable gripper jaws movable linearly forwardly and back to enter the space between the cylinders when they are separated, means for opening the gripper jaws to receive the leading edge of the sheet at the forward end portion of the stroke to grip the paper and lead same rearwardly, means to open the jaws near the rearward end of their stroke to release the sheet, a forwardly moving endless belt located below the gripper jaws when in the rearward end of their stroke to relay the released sheet to the front of the machine, guides for removing the sheet when released from th gripper jaws and guiding same onto the belt for delivery onto the front of the machine, means for rotating the lower feed roll to cause the sheet to advance into the space between the two cylinders sufliciently for the leading edge of the sh t to lodge into the gripper jaws and which is further characterized by pawls holding the printing cylinders apart after they have been separated, means for releasing the said pawls to allow th 13 cylinders topress a sheet of paper between them, comprising a micro-switch, a pivotally mounted horseshoe shaped working arm for the said upper and lower feed rolls, the said orking arm being so constructed and arranged as to fit into the groove of the lower feed roll with its upper end extending into the grooveuof the. upper feed roll when the upper feed roll is lowered without a sheet of paper between the two feed. rolls, but to be depressed by the Weight of the sheet and the action of the upper. feed: roll whena sheet of paper is present closing the said micro-switch, and a solenoid controlled by the said microswitch withdrawing. the said pawls.

CLYDE W. JOHNSON.

References Cited in the file of this patent UNITED STATES PATENTS Number Number Number 20 770,486-

16 Name- Date Lehrr Aug. 31, 1920 Blaine Apr. 5, 192 Fisher Oct. 21, 1930 Kranz' Apr. 24, 1934 Morse Aug. 7, 1934 Eckhard Oct. 8, 1935 Germann Dec. 1, 1935 Huck Mar. 10, 1942 Crafts. Aug. 22, 1944 Davidson Aug. 20, 19416 Horton et a1 Apr. 22, 1947 Davidson Jan. 30, 1951 Aberle Feb. 20, 1951 Janke Apr. 3, 1951 Johnson Mar. 25, 1952 FOREIGN PATENTS Country Date Germany Sept. 20, 1904

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