US 3664261 A
A sheet-fed lithographic offset printing press in which sheets are aerodynamically supported and directed in a single horizontal plane straight to and through individually driven and mechanically synchronized multi-color perfecting towers while the sheet is continuously gripped and moved by a single set of grippers at the leading edge so that only blanket printing cylinders touch the sheet, eliminating sheet transfer between the time the sheet leaves the feeder and the time it reaches the delivery.
Claims available in
Description (OCR text may contain errors)
United States Patent Dahlgren  May 23, 1972 STRAIGHT FEED PRESS  Inventor: Herold P. Dlltlgren, 726 Regal Row, Dallas, Tex. 75247  Filed: June 17, 1968  App1.No.: 737,521
 US. Cl ..101/l77, 101/184, 101/232, 101/229  Int. Cl. ..B4lI7/l2,B41f7/04  FleldolSe-reh ..101/l36,l74,175,177,216,
 References Cited UNITED STATES PATENTS 2,551,060 5/1951 Simmons 101/232 2,753,798 7/1956 Babst 101/232 2,794,390 6/1957 Burke 101/232 3,422,757 l/1969 Grobman et a1 ..101/232 1,348,253 8/1920 Uphnm ..101/23l 2,138,405 11/1938 ....101/183 3,179,404 4/1965 Felts et a1. ..271/79 3,196,788 7/1965 Knowles ..l0l/2l7 3,221,651 12/1965 Tagliasaechi. ....101/183 3,351,394 11/1967 Hooker ..308/9 Primary Examiner-Wil1iam 8. Penn Assistant ExaminerE. M. Goven Alt0mey-Howard E. Moore ABSTRACT A sheet-fed lithographic offset printing press in which sheets are aerodynamically supported and directed in a single horizontal plane straight to and through individually driven and mechanically synchronized multi-color perfecting towers while the sheet is continuously gripped and moved by a single set of grippers at the leading edge so that only blanket printing cylinders touch the sheet, eliminating sheet transfer between the time the sheet leaves the feeder and the time it reaches the delivery.
45Clahm,28DrowingFigures Patented May 23, 1972 INVENTOR ATTORNEY l5 Sheets-Sheet 1 Patented May 23, 1972 15 Sheets-Sheet 2 INVENTOR 191915 05 019 7565 5 BY M E I M ATTORNEY Patented May 23, 1972 3,664,261
15 Sheets-Sheet Ls HEPJLD I? DQ525195 ATTORNEY Patented May 23, 1972 3,664,261
15 Sheets-Sheet 4 INVENTOR W M w 1 9 ATTORNEY Patented May 23, 1972 3,664,261
15 Sheets-Sheet 5 Maw 19019152619677 ATTORNEY Patented May 23, 1 972 3,664,261
15 Sheets-Sheet 6 3& BY M 87W ATTORNEY Patented May 23, 1972 3,664,261
15 Sheets-Sheet '7 a E W A 2249 2.24
INVENTOR 6 19/9069 I. Dflf/LFAi/V ATTORNEY Patented May 23, 1972 IEFJ I kf in INVENT OR ATTORNEY INVENTOR 1 M w m M H. 0 3 P 0 L m 9 W M W 5 1E w mm mm t m mum s w 11 HI! w mm M v 2 1 7 '1 w :1 a mm w 3 2 mwn n; mun wt in W L1 M km w Q: Qm m n w m m mm a? P m ww ATTORNEY Patented May 23, 1972 3,664,261
15 Sheets-Sheet 1O H54 7 EXCHANGE/Q INVENTOR ll/YA'JM P Bil/615 5 BY W E ATTORNEY Patented May 23, 1972 3,664,261
15 Sheets-Sheet 11 BY W 'M ATTORNEY Patented May 23, 1972 15 Sheets-Sheet 1 2 ww r LJINVENTOR 55mm 5.00am? B M Z M ATTORNEY INVENTOR ATTORNEY Patented May 23, 1972 15 Sheets-Sheet 1L,
Patented May 23, 1972 3,664,261
15 Sheets-Sheet l5 fill/PHD F EMF/PM BY Mg ATTORNEY STRAIGHT FEED PRESS BACKGROUND OF THE INVENTION No significant advances have been made presenting new concepts in sheet-fed printing systems for decades. Printing systems designed for the sheet-fed printer are basically the same and allow printing on one side of the sheet at a time, requiring sheets to be turned over and rerouted through the press for single or multi-color perfecting. Sheets are progressively and meticulously transferred in serpentine fashion about transfer and impression cylinders and hopefully registered from one cylinder to another and from one printing unit to another until finally they emerge as a printed product. Printing units must be synchronized for color register through numerous drive and idler gears and consequently presses are extremely complex, massive units which are very expensive to manufacture because of numerous transfer and printing cylintiers and mechanisms related thereto.
One or two color sheet-fed perfectors have been developed heretofore. However, these machines were specifically designed for specific jobs, such as mass production of paperback books, and are totally unsuitable for high-speed production of four-color process printing on both sides of the paper.
Heretofore no sheet-fed press had the capability of printing on two sides of a sheet in as many as four colors by passing the paper through the press one time.
lt is the common and accepted practice in the printing industry to run a sheet to be printed through the sheet-fed press a multiplicity of times to attain multi-color printing on two sides ofa sheet. After each pass of the sheet through the press, the plates must be changed and the press made ready for the next pass to apply other colors or to print on the back of the sheet. It is readily apparent to those skilled in the printing art that a considerable amount of time is spent making sheet-fed presses ready to print and in attaining proper registry of the numerous components of the press.
In a typical four-color one-side printing press a sheet delivered from the feeder is caught by the gripper bars of a first transfer cylinder. The sheet is folded around the transfer cylinder and carried to the grippers on the first impression cylinder where the grippers of the transfer cylinder release the paper and it is caught by the grippers of the impression cylinder. The grippers on the impression cylinder rotate the paper into contact with the blanket cylinder where printing is accomplished in one color on one side of the sheet. When the grippers on the the impression cylinder release the sheet, grippers on a second transfer cylinder grasp the sheet, causing the printed surface to he in contact with the transfer cylinder while it is rotated to the grippers of a second impression cylinder. The grippers of the second transfer cylinder release the sheet as it is caught by the grippers of the second impression cylinder which rotates the sheet into contact with a second blanket where a second color is applied to the same side of the sheet. Grippers on a third transfer roller catch the sheet as it is released by the grippers of the second impression cylinder and the printed surface is again brought into contact with a transfer cylinder while it is being delivered to the grippers of a third impression cylinder. This process is continued until the sheet passes to delivery. When one side ofthe sheet is completed, the press is replated, the sheets are turned and refed through the press to print the other side of the sheet.
Virtually all sheet-fed printing presses heretofore developed have the characteristic of feeding the sheet serpentine fashion through the press while the grippers associated with each cylinder catch the sheet as it is being released by the grippers of the previous cylinder.
One of the major problems encountered by the printing industry lies in synchronizing the various cylinders whereby the sheet will be grasped and released at the proper moment for maintaining registry between the cylinders of successive towers so that colors do not overlap or separate.
Chains have been used in the past with limited success to transfer sheets from one printing station to another. Grippers supported by the chain have to be positively indexed to the printing station cylinders before sheet transfer can be accomplished with any degree of register between stations.
A chain has inherent limitations as a smooth transfer media because chordal motion of the links limit smooth flow; linear deformation of the chain results from numerous pivot joints; lubrication requirements at joints, to help prevent wear, noise, shock and vibration, present maintenance problems.
The gripper and chain transfer media could not, by itself, register the sheet between printing stations, even with the chain travelling precisely at cylinder speeds. As a compromise, grippers had to be loosely supported on the chain, moved from normal position, and indexed to printing station cylinders prior to actual sheet transfer at the cylinder. As soon as sheet transfer was accomplished and the gripper became separated from index with the cylinder, the gripper jumped or jerked back into its normal relation with the chain.
In the transfer system employed and disclosed herein, there is no contact between tape directed gripper bars and the printing cylinders thereby eliminating shock, vibration, wear, noise, mis-register and other apparent problems accompanied by chain supported grippers being indexed to cylinders. The printing cylinders are entirely independent of the sheet transfer mechanism and vice versa except for speed synchronization of cylinder surface speed with that of the tape.
Another problem has been the offsetting of wet ink on transfer cylinders from the freshly printed surface on the paper and consequently back on to the next sheet that is passed through the press. Heretofore, presses with a multiplicity of towers for applying more than one color of ink to the sheet were driven by a common drive through a complex gear train or through long shafts which have inherent distortion thereby increasing the problem of synchronizing components of the press thereby making precision registry more difficult.
Typical four-color one-side printing presses have an average of about 20 cylinders including the plate cylinders, blanket cylinders, impression cylinders, transfer cylinders and skeleton wheels.
Sheet-fed printing presses heretofore used have relatively low production speeds which never exceed 8,000 impressions per hour.
All sheet-fed presses heretofore used have basically the same complex ink fountain with keys to vary the ink flow and an ink train consisting on an average of about twenty rollers for smoothing and distributing the ink to the plate cylinder.
A universal characteristic of sheet-fed printing presses heretofore used has been the employment of massive bearers on each end of the plate and blanket cylinders to assure rotation of the cylinders without vibration when the cylinder load is reduced because of gaps in the cylinders. The use of bearers has been necessitated by limitations of bearings heretofore incorporated into the design of presses for journaling the cylinders.
Apart from the equipment design being basically the same, one only has to be briefly associated with problems in the industry to see that printing problems, too, are the same for the similarly designed presses; namely, extensive time and effort are required for make-ready; extreme difficulty in obtaining and maintaining register between colors; streaking and slur caused by gear lash and deformation or by vibration and shock of complex mechanism movements; offsetting caused by the printed side of the sheet being in contact with transfer cylinder and skeleton wheel surfaces; sheet or board fatigue; considerable downtime for maintenance caused by breakdown of the complex mechanical systems; problems relating to ghosting on certain printing layouts; problems relating to control of ink-water balance and sometimes the most neglected problem of all, that of requiring personnel having special skills, talents, experience and perseverance to "get the job done with the above mentioned type of printing systems.
All the above problems are related basically to problems involving lack of versatility, quality, economy and ease of operation, and are largely caused by the stereotype conventional design of the present day printing system.
Since the problems for the sheet-fed printer are not being readily solved by "updating and face-lifting" of the old concepts of printing, the only apparent alternative has been to switch to web-offset lithography. Here the printer can print several colors on two sides of the sheet at the same time with increased production. In addition to the multi-color perfecting capability the web-press is superior to the sheet-fed press in specific situations because higher production rates and lower break-even points are possible.
This at first would seem to be the answer, except for the fact that many of the problems existing in sheet-fed printing also exist in web-offset; namely, lack of color register caused by deformation of long drive shafts; basically the same kind ofink fountain with keys used in sheet-fed presses; a complicated train of rollers and conventional water fountain systems; common drive for the entire press; roller or ball-bearings with massive cylinder bearers on the plate and blanket cylinders; and printing cylinders are universally the same circumference as the finished sheet cut'off length, allowing absolutely no time for recovery of the inking form rollers after they finish a print ing cycle.
Apart from problems common to the conventional sheetfed operation, switching from sheet fed to web-offset lithography presents other distinct disadvantages.
A web-offset press is limited to one sheet length equal to the circumference of the plate cylinder. When shorter sheet lengths are required excessive waste results from non-use of the unprinted web portion. Another complete press system must be designed, manufactured, purchased and used for printing different sheet sizes to avoid excessive waste of paper. Web presses are generally more expensive because of complex folders, dryers, chill devices, etc., necessary. More time is usually required for make-ready and more waste is encountered since the web must be running through the press and desirably at production speeds while registering and while color correction changes are being made because it is difficult to compensate for wind-up of the drive system when the press is stopped. Crews trained for printing on sheet-fed equipment find that they must learn new skills when using web equipment.
The printing industry is faced with a dilemma of the sheetfed and web-fed printing operations, each having decided advantages over the other, while sharing common problems which are inherent in the stereotyped press design which has been virtually unchanged for decades.
SUMMARY OF THE INVENTION l have developed a novel sheet-fed offset lithographic printing press which incorporates the advantages of sheet-fed equipment heretofore employed and the advantages of the web-press, while eliminating deficiencies of each.
By eliminating elements which did not contribute to the success of the lithographic printing press but which prevented or defeated it, I have developed a sheet-fed printing press which has the capability of perfecting, i.e., printing on both sides of the sheet at the same time, in any desired number of colors while the sheet is passed one time through the printing press.
I have eliminated all transfer cylinders, impression cylinders and skeleton sheets which have been used heretofore for feeding a sheet through the press serpentine fashion.
I have developed a sheet-fed printing press which incorporates a straight through and continuous sheet transfer principle similar to the feeding style of a web press whereby the sheet is grasped by a gripper bar after being delivered to the sheet transfer mechanism by a conventional feeder and the sheet is directed in an uninterrupted horizontal plane straight to and through one or a plurality of printing towers where printing is accomplished selectively on one side; or, on both sides of the sheet at the same instant, or any combination thereof in any desired number of colors. This eliminates tuming the sheet over after printing on one side and re-feeding it through the printing system. This also eliminates the necessity for numerous cylinders, constantly gripping and releasing the sheet as has been required heretofore.
Eliminating the complex ink fountain used on conventional presses, l have developed a press with a novel ink fountain, having a rigid doctor blade and a minimum number of rollers in the ink train for applying ink to the plate cylinder.
l have eliminated the need for bearers on the blanket and plate cylinders by the use of a novel journal, which has not been used heretofore in printing presses, which operates on hydrostatic principles offering a new and unexpected result, in that it eliminates the need for bearers.
l have eliminated the common drive system and have incorporated a novel system for driving the printing towers by individual drive motors while maintaining register for multicolor printing by the use of synchronizing links for maintaining critical elements of each printing tower and the sheet transfer system in synchronization at all times.
It is a primary object of the invention to provide a sheet-fed printing press which incorporates a sheet transfer system which moves the sheet in virtually a straight horizontal line, eliminating transfer and impression cylinders, in which the sheet length is unrelated to and may be variably less than the circumference of the printing cylinder, thereby incorporating the straight feed characteristic of the web press with the variable cut-off characteristic of the sheet-fed press.
Another object of the invention is to provide a sheet-fed press in which the sheet is continuously gripped by a single set of grippers from the time the sheet enters the press until delivery, offering the ultimate in register for multi-color printmg.
Another object of the invention is to provide a printing press in which the sheet is grasped at the leading edge by a set of grippers and aerodynamically supported and directed to and through one or more printing towers.
A further object of the invention is to provide a sheet-fed printing press which may be used as a perfector to print any desired number of colors on both sides of the sheet, eliminating the need for a second pass through the press.
A still further object of the invention is to provide a sheet transfer system capable of gripping and registering two sheets simultaneously in a single set of grippers to move the sheets through perfecting printing towers to print on one side of each sheet.
A further object of the invention is to provide a printing press in which the only cylinders which touch the paper are the blanket printing cylinders, thereby eliminating all costly transfer cylinders, impression cylinders, skeleton wheels, and related complex gripper mechanisms commonly used in sheetfed presses.
A further object of the present invention is to eliminate marking caused by the offsetting of wet ink on sheets exposed to transfer cylinders and subsequent ofi'setting of the ink to subsequent sheets.
A still further object of the invention is to provide a sheetfed printing press having a sheet gripping mechanism carried by an endless flexible conveyor having an in-line feeder and delivery, allowing fast but accurate control of the speed of the paper through the press.
A still further object of the invention is to provide a sheetfed printing press in which the sheet travels through the path of least resistance thereby utilizing natural phenomena such as the cantilever effect on the sheet as it is grasped in the nip between the blanket cylinders, causing the sheet to lie tangent to the blanket cylinders due to its modulus of elasticity and also phenomena involving boundary layers of air and air pressure at the nip between opposing blanket cylinders.
A still further object of the invention is to provide a printing press having a simplified continuous inking and dampening system, eliminating problems relating to ink-water balance, emulsification, ghosting, one turn roller streaks and hickies".
A still further object of the invention is to provide a printing press having a novel plate cylinder having a printing plate covering approximately one-half of the circumference thereof and an ink receptive recovery plate covering substantially the other half thereof associated with the ink train, allowing recovery time for redistribution of the ink on the form rollers of the ink train to eliminate ghosting.
Another object is to provide a printing press having an ink fountain which does not supply an overabundance of ink to the inking form rollers while the form rollers are in the plate cylinder gap, thereby eliminating one turn roller streak.
A still further object of the invention is to provide a printing press having an ink fountain utilizing a rigid doctor blade in contact with a resilient roller wherein the thickness of the ink film to be applied may be metered continuously and applied at a controlled, uniform rate in regulated quantities as demanded by the printing layout.
A still further object of the invention is to provide a sheetfed printing press which may serve as a perfector in which printing is achieved on both sides of the sheet at precisely the same moment as the sheet is drawn between adjacent blanket cylinders and touches the cylinders only at the printing nip.
A still further object of the invention is to provide a sheetfed printing press in which each blanket cylinder serves the dual purpose of a blanket cylinder for offsetting ink to the sheet and simultaneously as an impression cylinder for the blanket which is offsetting ink to the opposite side of the sheet.
These and other objects are effected by my invention as will be apparent in the following description taken in conjunction with the accompanying drawings.
DESCRIPTION OF THE DRAWING The accompanying drawings illustrating the present invention are provided so that the invention may be better and more fully understood, in which:
FIG. I is a side elevational view of the operator side of the printing press;
FIG. II is a top plan view of the printing press having the inker broken away;
FIG. III is a side elevational view of the drive side of the printing press;
FIG. IV is a cross sectional view taken along lines IV-IV of FIG. II;
FIG. V is a sectional view through a typical printing tower taken along lines V-V of FIG. ll;
FIG. VI is a cross sectional view taken along lines VIVI of FIG. Il showing a typical tape wheel in the delivery station;
FIG. VII is an enlarged elevational view of a typical gripper bar looking in the direction indicated by the arrows along lines VIIVII ofFIG. II;
FIG. VIII is a cross sectional view taken along lines VIII- VIII of FIG. VII through atypical gripper bar with the gripper in closed position;
FIG. IX is a cross sectional view taken along lines IX-IX of FIG. II through a typical gripper bar with the gripper in the open position at the delivery station;
FIG. X is a cross sectional view taken long lines XX of FIG. I showing the details of construction of the sheet transfer mechanism at the delivery station;
FIG. XI is a partially sectionalized fragmentary view illustrating the details of construction and mounting of a typical plate cylinder;
FIG. XII is a partially sectionalized fragmentary view illustrating details of construction and mounting of the upper blanket cylinder;
FIG. XIII is a diagrammatic view illustrating a suitable hydraulic circuit for providing lubrication to the hydrostatic bearing bearers utilized for journaling the plate and blanket cylinders;
FIG. XIV is an enlarged cross sectional view taken along lines XlV-XIV of FIG. XIII;
FIG. XV is a perspective view of a portion of a hydrostatic bearer illustrating a suitable configuration of a recess utilized for receiving lubricant for the bearing;
FIG. XVI is a perspective view of a portion of a hydrostatic bearer illustrating a suitable configuration of the annular rings utilized for draining lubricant from the bearing;
FIGS. XVII, XVIII and XIX illustrate the relationship between the blanket cylinders and the gripper bar assembly which continuously grips the sheet as the gripper bar assembly and sheet enter (FIG. XVII), pass through (FIG. XVIII) and leave (FIG. XIX) the cutaway portion of respective blanket cylinders;
FIG. XX is an enlarged cross sectional view illustrating the nip between opposing blanket cylinders while printing is being accomplished on a sheet;
FIG. XXI is a partially sectionalized fragmentary view illustrating details of construction and mounting of the lower blanket cylinder;
FIG. XXII is an enlarged cross sectional elevational view cut transversely through the rollers of the upper ink train;
FIG. XXIII is a cross sectional view taken along lines XXIII-XXIII of FIG. XXII;
FIG. XXIV is a cross sectional view taken along lines XXIVXXIV of FIG. XXII:
FIG. XXV is a cross sectional view taken along lines XXV- XXV of FIG. XXII illustrating details of construction of the primary inker;
FIG. XXVI is an enlarged cross sectional view, similar to FIG. XXII, ofa second embodiment of the primary inker;
FIG. XXVII is an elevational view, with parts broken away, of a crankplate in the synchronizing system;
FIG. XXVIII is a cross sectional view taken along lines XX- VIll-XXVIII of FIG. XXVII.
Numeral references are employed to indicate the various parts as shown in the drawings and like numerals indicate like parts throughout the various figures of the drawing.
DESCRIPTION OF A PREFERRED EMBODIMENT Referring to FIG. I of the drawings the numeral I generally designates a sheet-fed multi-color perfecting lithographic printing press.
A feeder mechanism 2 feeds sheets of unprinted paper from a stack 4 by conventional means to a swing gripper 6. The swing gripper 6 accelerates individual sheets 5 to the velocity of gripper bars 8 carried by the sheet transfer mechanism, generally designated by the numeral 10. Sheet transfer mechanism 10 consists of tape wheels 12a, 12b and 14a, 14b which carry tapes 16a and 16b, having gripper bars 8 mounted therebetween for moving individual sheets 5 through the printing press, as will be hereinafter more fully described.
A plurality of printing towers I8 and 20 is provided, giving the press a multi-color perfecting capability. Conventional leveling devices such as jack screws (not shown) may be utilized for tower leveling.
A delivery mechanism 22 grips the individual sheets 5 as they are released by gripper bars 8 of the sheet transfer mechanism 10 and positions the sheets by conventional means in a stack of printed sheets 24.
Referring to FIGS. II and V of the drawing, each printing tower l8 and 20 has a side frame 26 on the operator side and side frame 28 on the drive side of the printing press joined by tie bars 30 forming a strong rigid structure upon which various components of the press are mounted. Feeder 2 and delivery 22 have operator-side side frames 2a and 22a and drive-side side frames 2b and 22b respectively. Structural ties 31 join the side frames of individual towers 18 and 20 and side frames of the feeder 2 and delivery 22.
Primary inkers 32 and secondary inkers 34 cooperate with dampeners 36 to provide a proper balance of ink and dampening fluid to the plate cylinders 38, which are duplicated at the upper and lower ends of the tower.
PLATE CYLINDER Plate cylinders 38, FIGS. V and XI, are rotatably journaled at opposite ends thereof in side frames 26 and 28 in bearings 27 and 29. It should be noted that plate cylinders 38 differ from conventional plate cylinders in two very important aspects.
First, the printing plate 40 does not cover substantially all of the circumference of plate cylinder 38, FIG. V. Printing plate 40 wraps around substantially one-half of the circumference of plate cylinder 38.
Both web and sheet-fed presses heretofore developed have covered as much of the surface of the plate cylinder as possible with the plate. This has been necessitated in web presses to reduce waste of paper and in the sheet-fed presses to make a more compact press.
Plate 40 is detachably secured to plate cylinder 38 by conventional plate clamps 42 conventionally positioned in gap 39. An ink pad 44 is mounted in a similar manner as plate 40 and covers substantially the remaining circumference of plate cylinder 38.
Ink pad 44 is an ink receptive plate having an effective diameter slightly greater than that of the effective diameter of the plate 40. In view of the fact that the surface of the ink pad 44 is of greater radial distance from the center of the plate cylinder 38 than the radial distance from the center of the plate cylinder to the surface of plate 40, ink is distributed over ink pad 44 by primary inker 32 and the ink is spread over the form rollers of the secondary inker 34 from pad 44, while plate 40 does not contact rollers of the primary inker but receives ink only from the form rollers of the secondary inker.
Utilization of the ink pad 44 allows great simplification of the conventional ink train, while overcoming ghosting problems often encountered by lithographers using conventional inking systems. Since plate 40 does not cover the substantial circumference of plate cylinder 38, form rollers in the ink fountain have sufiicient time to recover, eliminating ghosting as will be hereinafter described.
The second important deviation of plate cylinder 38 from the conventional plate cylinder is the elimination of bearers. Bearers have been universally used on plate cylinders and blanket cylinders to prevent vibration when cutaway portions of the plate cylinder and blanket cylinder come into rolling contact.
Plate cylinder 38 has reduced diameters at opposite ends thereof, forming journals 38a and 38b which are supported by bearings 27 and 29 respectively in the side frames 26 and 28. One end 380 of plate cylinder 38 is captured by the lateral register adjustment 58, as will be hereinafter explained, while the other end 38b is free to slide axially through bearing 29. This construction provides automatic compensation for ther mal expansion of plate cylinder 38.
I have eliminated the need for bearers by replacing conventional hall, sleeve and roller bearings with a hydrostatic bearer 46, FIGS. XI-XVI, which is machined to very close tolerance between bearing sleeve 27 and 29 and journals 38a and 38/7 on the plate cylinders 38 and journals 48a and 48b on blanket cylinders 48, allowing virtually no vibration of the plate cylinder as will be hereinafter more fully explained.
BLANKET CYLINDER When printing is being accomplished blanket cylinders 48 are in rolling contact with plates 40 on plate cylinders 38, FIG. V. On each upper and lower unit, blanket 50 is detachably secured to blanket cylinder 48 by conventional blanket clamps 52 and is of substantially the same length as plate 40, thereby covering the same proportion of the circumference of blanket cylinder 48 as plate 40 covers on plate cylinder 38 which is equal in diameter to blanket cylinder 48. Each blanket cylinder 48 has a recessed area 54 on the outer surface, providing clearance for the ink pad 44 on plate cylinder 38 to prevent contact between the blanket cylinder 48 and the ink pad 44.
It should be noted that as hereinbefore explained that blanket cylinders 48 do not have conventional bearers on each end thereof, but each blanket cylinder 4! has a journal 48a and 48b at opposite ends thereof supported in hydrostatic bearings 46 which will be described in detail hereinafter.
Each blanket cylinder 48 has a recessed gap or cutaway portion 56 on the outer surface. FIGS. V, XVII, XVIII and XIX, allowing gripper bars 8 to move therebetween as they rotate. Referring to FIGS. II, IV, V and XXI, it should be noted that each blanket or printing cylinder 48U and 48L has reduced diameter areas adjacent each end thereof. Tracks 224 and 226 and flexible conveyors 16a and 16b extend through openings between the cylinders formed by the reduced diameter areas. Gripper bars 8 enter gaps 56 and conveyors 16a and 16b move freely along an unobstructed path between the printing cylinden 48 and 48L in non-engaging, non-driving relationship with the cylinders.
ADJUSTMENT AND THROW OFF Each plate cylinder 38 has conventional lateral color registering adjustment mechanism 58, FIG. I and XI. A suitable means for establishing and maintaining lateral register comprises a worm 58a and a worm gear 58b for driving a spur gear 580 which in turn meshes with gear teeth on a threaded adjustment screw 58d whereby rotation of the worm 580 will cause the threaded adjustment screw 58d to be moved laterally, thereby moving plate cylinder 38 laterally with respect to the side frames 26 and 28. Adjusting screw 58d threadedly engages collar S8e, rigidly connected to the operator-side side frame 26 by bolts 58]". Adjusting screw 58d has annular thrust bearing 58g mounted therein which is captured between shoulders 38c on cylinder 38 and plate 58h secured by bolts 58: to the end of plate cylinder journal 38a.
A throw-off mechanism is utilized to separate the blanket cylinders 48U and 48L from plate cylinders 38U and 381. respectively and to separate the upper blanket cylinder 48U from lower blanket cylinder 48L when the last sheet passes from the feeder or when a sheet 5 fails to feed. A suitable mechanism, FIGS. I and V, comprises a throw-off hydraulic cylinder 60 actuated by an electric eye or other suitable means (not shown), pivotally connected to a crank 62 wherein actuation of throw-off cylinder 60 causes crank 62, which is rigidly connected to cross shaft 64, to rotate shaft 64. Crank 62, rigidly connected to shaft 64, also moves adjustable link 70 to rotate a second crank 72 rigidly secured to a second cross shaft 74. Rotation of the first and second cross shafts 64 and 74 respectively results in rotation of cranks 76 which are rigidly secured to each of said cross shafts. A rod eye 78 is pivotally connected to each crank 76 and has an adjustment screw 82 threadedly engaged therein. Screw 82 extends through and threadedly engages pin 82b and is secured relative thereto by lock nuts 82c and 82d threadedly engaging adjustment screw 82. Pin 82b, FIGS. XII and XXI, is rotatably journaled in bushings 82e, rigidly connected to outwardly extending lugs 800 on throw-off crank 80. Throw-off crank is rigidly connected to eccentric bushing 27a and 29a of hydrostatic bearing 46. The eccentricity of bushings 27a and 290 causes opposing blanket cylinders 48L and 48U to move to an off impression position when throw-ofi cylinder 60 is actuated. It should be apparent that actuation of throw-off cylinder 60 results in rotation of throw-off crank 80 and ec centric bushings 27a and 29a, causing each blanket cylinder 48U and 48L to move from contact with plate cylinders 38U and 38L respectively and causes blanket cylinders 48U and 48L to be separated.
Paper pressure adjustment 84, FIGS. I, V and XXI, consists of a worm 84a rotatably mounted on the operator-side side frame 26, which rotates a worm gear segment rigidly connected to cross shaft 84b, transmitting rotation to lever arm 84c rigidly connected to cross shaft 84b. An adjustable rod 84a is pivotally connected between lever arm 84c and the paper pressure eccentric 84c.