U.S. patent number 3,785,287 [Application Number 05/249,944] was granted by the patent office on 1974-01-15 for sheet interrupter.
Invention is credited to Harold P. Dahlgren.
United States Patent |
3,785,287 |
Dahlgren |
January 15, 1974 |
SHEET INTERRUPTER
Abstract
Sheet interrupter means for a sheet-fed printing press wherein
upper and lower printing cylinders are supported by eccentric
bearings permitting simultaneous actuation of the upper and lower
cylinders between printing and "off-impression" positions. A
throw-off cylinder actuates a series of links to rotate the
eccentric bearings.
Inventors: |
Dahlgren; Harold P. (Dallas,
TX) |
Family
ID: |
26940482 |
Appl.
No.: |
05/249,944 |
Filed: |
May 3, 1972 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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737521 |
Jun 17, 1968 |
3664261 |
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Current U.S.
Class: |
101/247; 101/137;
101/184 |
Current CPC
Class: |
B41F
21/08 (20130101); B41F 7/12 (20130101); B41F
31/301 (20130101); B41F 13/36 (20130101); B41P
2213/734 (20130101) |
Current International
Class: |
B41F
13/24 (20060101); B41F 31/30 (20060101); B41F
13/36 (20060101); B41F 7/00 (20060101); B41F
21/08 (20060101); B41F 21/00 (20060101); B41F
7/12 (20060101); B41F 31/00 (20060101); B41f
013/24 () |
Field of
Search: |
;101/137,218,247,229,182,184,185 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Pulfrey; Robert E.
Assistant Examiner: Coven; E. M.
Attorney, Agent or Firm: Howard E. Moore et al.
Parent Case Text
CROSS REFERENCE TO RELATED APPLICATION
This application is a continuation-in-part of my co-pending U.S.
Pat. application Ser. No. 737,521, filed June 17, 1968, now U.S.
Pat. No. 3,664,261 entitled STRAIGHT FEED PRESS.
Claims
Having described my invention, I claim:
1. In a sheet fed printing press, a feeder station; a delivery
station; at least one cylinder support, including spaced side
members intermediate the feeder and delivery stations; a printing
cylinder journaled between the side members; an impression cylinder
adjacent the printing cylinder, at least one of said cylinders
having a gap formed therein; throw-off means secured to said
printing cylinder and to said impression cylinder, said throw-off
means being movably secured to the side members; means to rotate
the said cylinders; means to apply ink to the printing cylinder;
flexible conveyors movably extending along each side of the press
from the feeder station to the delivery station; spaced elongated
sheet engaging means extending between the conveyors and movable
from the feeder station to the delivery station, said sheet
engaging means being adapted to engage a sheet at the feeder
station and continuously convey same between the surfaces of the
printing and impression cylinders to the delivery station; means to
secure the sheet engaging means to the flexible conveyors adjacent
ends of the sheet engaging means; means to synchronize the rotation
of the cylinders and the sheet engaging means to cause the gap and
the sheet engaging means to be simultaneously moved into coinciding
relationship relative to each other as the cylinders rotate, the
sheet engaging means being spaced to enter the gap and move between
the printing and impression cylinders in non-engaging relationship
therewith; and actuating means to move the throw-off means to move
the printing cylinder and the impression cylinder toward and away
from a sheet moved therebetween by said sheet engaging means.
2. The combination called for in claim 1 wherein the throw-off
means comprises, upper and lower bearings having outer surfaces
eccentric to walls of a bore extending therethrough, ends of said
printing cylinder and said impression cylinder being rotatably
supported in the bores; and wherein said actuating means comprises,
means secured to each of said upper and lower bearings arranged to
rotate the bearings to move the printing and impression
cylinders.
3. In a sheet fed printing press, a feeder station; a delivery
station; at least one cylinder support, including spaced side
members intermediate the feeder station and the delivery station;
throw-off means movably secured to each of said side frames; a
printing cylinder rotatably journaled in said throw-off means; an
impression cylinder rotatably journaled in said throw-off means
adjacent the printing cylinder, at least one of said cylinders
having a gap formed therein and extending longitudinally thereof to
allow passage of a gripper member between said cylinders; means to
apply ink to the printing cylinder; continuous flexible sheet
transfer means movably extending from the feeder station to the
delivery station; means to drive the sheet transfer means at a
preselected constant speed; gripper members carried by the sheet
transfer means adapted to receive and grip the edge of the sheet at
the feeder station and continuously convey same to the delivery
station; carrier guide means adjacent opposite sides of the press
to direct the gripper members along a substantially straight path
between opposite ends of the press; power transmission means to
rotate said cylinders at a preselected constant speed;
synchronizing means secured to the power transmission means and to
the means to drive the sheet transfer means to cause the sheet
transfer means and the printing cylinder to move in a selected
unchanging speed relationship; and actuating means secured relative
to at least one of the side frames to actuate the throw-off means
from an off-impression position to an on-impression position
wherein each of said printing cylinder and said impression cylinder
is moved to engage a sheet carried by said gripper members
positioned between the printing cylinder and the impression
cylinder.
4. A method of printing comprising the steps of: positioning the
leading edge of a sheet in a gripper element; moving the gripper
element along a substantially straight path toward, through and
away from a plurality of printing stations whereby the sheet when
passing between adjacent cylinders in each printing station is
maintained substantially in line contact with the cylinders;
rotating first and second throw-off eccentric bearings having
printing and impression cylinders mounted therein such that
printing and impression cylinders are simultaneously moved into
engagement with opposite sides of the sheet; and disengaging the
leading edge of the sheet from the gripper element after the sheet
has been moved through each of the printing stations.
5. The method of claim 4 wherein the step of moving the gripper
element comprises, rotating endless flexible conveyors having a
gripper element extending therebetween; and with the addition of
step of synchronizing movement of the conveyors with movement of
surfaces of the printing and impression cylinders.
Description
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 cylinders 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 commercially successful 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.
It 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
of a 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 impression cylinder
release the sheet, grippers on a second transfer cylinder grasp the
sheet, causing the printed surface to be 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 of the sheet is completed,
the press is replated, the sheets are turned and re-fed through the
press to print the other side of the sheet.
Virtually all sheet-fed printing presses heretofore developed have
the characteristics 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. However, grippers
supported by the chain were positively indexed to the printing
station cylinders in an attempt to regain register which was
periodically lost between printing 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 of an ink train
consisting of an average of about 20 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 perservance to "get the job done" with the
above mentioned type of printing system.
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 of ink 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 printing cycle.
Apart from problems common to the conventional sheet-fed 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 dilemna of the sheet-fed 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
I 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 wheels 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 web presses 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 along an
uninterrupted path having no abrupt changes in direction 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 turning 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,
I 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.
I 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.
I 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 multi-color 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 printing.
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 printing
cylinders, thereby eliminating all costly transfer cylinders,
impression cylinders, skeleton wheels, and related complex gripper
mechanisms commonly used in sheet-fed 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 off-setting of the ink to subsequent
sheets.
A still further object of the invention is to provide a sheet-fed
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 sheet-fed
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 sheet-fed
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 sheet-fed
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 DRAWINGS
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. II;
FIG. VI is a cross sectional view taken along lines VI--VI of FIG.
II 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
VII--VII of FIG. II;
FIG. VIII is a cross sectional view taken along lines VIII--VIII of
FIG. VII through a typical 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 along lines X--X 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
XIV--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 repective 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 XXIV--XXIV 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, of a 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
XXVIII--XXVIII of FIG. XXVII;
FIG. XXIX is a cross sectional view taken along line XXIX--XXIX of
FIG. III;
FIG. XXX is a fragmentary perspective view of a modified form of
synchronizing apparatus;
FIG. XXXI is a fragmentary perspective view of a modified form of a
tape wheel;
FIG. XXXII is a cross sectional view taken along line XXXII of FIG.
XXXI;
FIG. XXXIII is a diagramatic view of a modified form of the inker;
and
FIG. XXXIV is a diagramatic view illustrating sheet flow.
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 FIGS. I and XXXIV of the drawings the numeral 1
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 suitable 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 comprises 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 18 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 suitable means in a stack of printed sheets
24.
Referring to FIGS. II and V of the drawing, each printing tower 18
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 sufficient
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 38a 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 thermal expansion of plate cylinder
38.
I have eliminated the need for bearers by replacing conventional
ball, 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 38b 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 48 which is equal in diameter to
blanket cylinder 48. Each blanket cylinder 48 has a recessed area
54 on the outer surface, providng 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 48 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 gap or cutaway portion 46 on the
outer surface, FIGS. V, VXII, VXIII and XIX, allowing gripper bars
8 to move therebetween as they rotate.
ADJUSTMENT AND THROW OFF
Each plate cylinder 38 has suitable 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 58c which in turn
meshes with gear teeth on a threaded adjustment screw 58d whereby
rotation of the worm 58a 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 58e, rigidly connected to the
operator-side side frame 26 by bolts 58f. 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
58i to the end of plate cylinder journal 38a.
A suitable throw-off mechanism is utilized to separate the blanket
cylinders 48U and 48L from plate cylinders 38U and 38L 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 80a on throw-off crank 80. Throw-off
crank 80 is rigidly connected to eccentric bushing 27a and 29a of
hydrostatic bearing 46. The eccentricity of bushings 27a and 29a
causes opposing blanket cylinders 48L and 48U to move to an off
impression position when throw-off cylinder 60 is actuated. It
should be apparent that actuation of throw-off cylinder 60 results
in rotation of throw-off crank 80 and eccentric 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 84d is pivotally connected
between lever arm 84c and the paper pressure eccentric 84e.
It should be noted that paper pressure eccentric 84e is provided on
lower blanket cylinders 48L only. Paper pressure eccentric 84e,
FIG. XXI, is rotatably journaled in the operator-side side frame 26
and the drive-side side frame 28, having eccentric bushings 27a and
29a of hydrostatic bearer 46 rotatably journaled therein. It should
be readily apparent that rotation of worm 84a results in rotation
of paper pressure eccentric 84e, causing the lower blanket cylinder
48L to be moved relative to upper blanket cylinder 48U, thereby
providing means for adjusting the paper pressure between adjacent
blanket cylinders.
Circumferential register adjustment 86, FIGS. III and XI, provide a
means for rotating the upper plate cylinder 38U or the lower plate
cylinder 38L relative to plate cylinder gears 108 and 100
respectively, and allows rotation of one plate cylinder relative to
the other. Adjustment 86 includes an outwardly extending lug 86a on
each plate cylinder gear 100 and 108, having a worm gear 86b
rotatably journaled therein meshing with gear segment 86c connected
by bolts 86d to bushing 86e pinned at 86f to journal 38b of each
plate cylinder 38U and 38L. It should be apparent that rotation of
worm 86b associated with the plate cylinder in one tower will
impart rotation thereto, providing circumferential adjustment
thereof relative to the corresponding plate cylinders of other
printing towers for color register. The blanket cylinders 48U and
48L may be adjusted circumferentially relative to each other,
utilizing set screws 126 in crank plates 116, FIGS. XXVII and
XXVIII, as will be hereinafter more fully explained.
Utilizing set screws 126, the blanket cylinder gaps 56 may be
positioned to begin printing at the desired location on each side
of sheet 5 and will allow gripper bars 8 to pass through blanket
gaps 56.
Referring to FIG. III of the drawing, each printing tower 18 and 20
has an individual drive consisting of a variable speed motor 90
having a drive sheave 92 mounted on the shaft thereof. Belts 94 are
carried on drive sheave 92 and driven sheave 96 rotatably journaled
on side frame 28 of the drive side of each tower 18 and 20. Driven
sheave 96 is rigidly connected to a lower plate cylinder drive gear
98 which meshes with the lower plate cylinder gear 100. Rotation of
the lower plate cylinder gear 100 imparts rotation to lower plate
cylinder 38L. Lower blanket cylinder 48L has a gear 102, having
interrupted teeth 102a (FIG. XXIX), rigidly connected thereto which
meshes with lower plate cylinder gear 100 imparting rotation to
lower blanket cylinder 48L.
A lower idler gear 104 meshes with the lower plate cylinder gear
100 and with an upper idler gear 106 which in turn meshes with
upper plate cylinder drive gear 108, rigidly connected to upper
plate cylinder 38U. The upper plate cylinder gear 108 meshes with
the upper blanket cylinder gear 110, having interrupted teeth 110a,
rigidly connected to the upper blanket cylinder 48U.
From the foregoing it should be readily apparent that motor 90
drives the lower plate cylinder and the lower blanket cylinder
while transmitting power through idler gears 104 and 106 to drive
the upper plate and blanket cylinders.
The pitch diameters of plate cylinder gears 100 and 108 and blanket
cylinder gears 102 and 110 coincide with the peripherial surfaces
of plate cylinders 38L and 38U and blanket cylinders 48L and 48U
respectively, such that no slippage occurs at the plate and blanket
nip 38n when the cylinders are in pressure contact.
Plate cylinder gears 100 and 108 are identical. Blanket cylinder
gears 102 and 110 are identical except that teeth 102a on gear 102
and teeth 110a on gear 110 are interrupted or offset in opposite
directions to prevent driving or interference therebetween. The
surface speed of each cylinder is the same. Exact surface speed
relationship is obtained between the plate cylinder, blanket
cylinder and paper by placing packing 38p and 48p under the plates
40 and blankets 50, thereby packing same relative to the pitch
diameters of the gears 100, 108, 102 and 110; by adjusting the
pressure between adjacent plate and blanket cylinders (screw 82);
by adjusting the paper pressure (adjustment 84); and by
synchronization (links 132 and 134) of individual towers 18 and
20.
Idler gears 104 and 106 are mounted on stub shafts 112, FIG.
XXVIII, which are rigidly secured to the side frame 28. A retainer
plate 114 is bolted or otherwise rigidly secured to the end of each
stub shaft 112 to prevent axial movement of the idler gears 104 and
106 relative to the stub shafts 112.
A crankplate 116 and counterbalance 116w are rigidly connected to
each idler gear 104 and 106 by bolts 118 which pass through
elongated openings 120 in the crankplate 116. The elongated
openings 120 allow circumferential adjustment between the
crankplate 116 and the idler gear.
A stop block 122 is securely attached as by cap screws 124 to the
idler gear 104. Set screws 126 in crankplate 116 may be adjusted
with relation to stop block 122, thereby causing crankplate 116 and
counterbalance 116w to rotate relative to the idler gear 104.
Crankplate 116 may be adjusted or rotated with respect to idler
gear 104 by lossening bolts 118 and adjusting set screws 126
relative to stop block 122, causing crankplate 116 to rotate to the
desired position and then tightening bolts 118 through elongated
holes 120 to secure the crankplate 116 and counterbalance 116w to
idler gear 104.
Each crankplate 116 has an outwardly extending crankpin 128 thereon
upon which a bearing 130 is pivotally mounted. Crankplate 116 on
idler gear 104 of printing tower 18 is connected through a lower
synchronizing link 132 to crankplate 116 on idler gear 104 of
printing tower 20, best illustrated in FIG. III, forming a rigid
mechanical linkage, causing idler gear 104 of each printing tower
to rotate in synchronization.
The upper idler gears 106 of each printing tower 18 and 20 are
similarly connected by an upper synchronizing link 134.
It should be noted that the printing stations are self-contained
units powered by individual motors 90. Synchronization of multiple
printing stations is accomplished by mechanical linkages 132 and
134 indirectly connecting the rotating cylinders. Load sharing is
accomplished by mechanical linkages 132 and 134 so that each motor
carries its portion of the load of all stations. Loads will be
normally equal at each tower.
Individual drive motors 90 at each printing station are driven in
unison by one central control 90b. This provides speed
synchronization and load sharing. Controls 90a are located at each
printing tower for necessary maintenance and operation from that
point. Printing tower controls 90a shall consist of: jog forward;
jog reverse; emergency stop; and warning. The jogging operations
will be performed at low speeds which can be adjusted for optimum
convenience. The emergency stop will shut down the press in minimum
time. The warning operation must be energized before any jogging
may be performed. These controls are conventional and well known to
persons skilled in the art.
A drive motor 90 may also be provided for the sheet transfer
mechanism as hereinafter explained wherein all drive motors
(connected thru the synchronizing linkages between each station and
between the last station and the transfer mechanism) share the
total load imposed by the printing stations 18 and 20 plus the
sheet transfer mechanism 10. One control 90b furnishes power to all
main drive motors 90.
Motors 90 are all connected in parallel so that one common field
voltage from the control 90b supplies all motors 90, and one common
armature voltage from the control also supplies all motors. Field
supplies to each motor may be individually trimmed to balance
electrical speed.
The dampener 36 is independently driven and controlled as fully
explained in U.S. Pat. No. 3,168,037. The dampener drive will be
variable speed with controls at each station and remote controls at
a console or master station and speed indication and trim controls
at the delivery end of the printing system.
Printing presses heretofore developed have utilized a common drive
system consisting of a single motor and long shafts and complicated
gear trains for delivering power to the individual printing towers.
When a long bar or shaft is subjected to a torque the cross section
at one end rotates with respect to the cross section at the other
end, resulting in twist or angular displacement of one end of the
shaft with respect to the other end. Deflection of drive shafts
causes the printing towers to get out of register which results in
poor printing quality. Likewise presses utilizing complicated gear
trains experience gear lash with the same accompanying register
problems.
Synchronizing links 132 and 134 will be subjected to slight
differential loading and therefore the deflection problem
heretofore experienced will be non-existent.
While the feeder 2 and delivery mechanism 22 may be driven by
individual drive motors in the same manner as heretofore described
with respect to printing towers, the particular embodiment shown in
the drawing utilizes sections 136 and 138 of links 132 and 134 to
transmit power from motor 90 of printing tower 18 and 20 through
idler gears 104 and 106 to drive gears 140 and 142 rotatably
journaled on the drive-side side frame 2b and 22b of the feeder
mechanism 2 and the delivery mechanism 22, FIG. X. The end section
136 of lower synchronizing link 132 is pivotally connected to
crankpins 128 on crankplates 116, one of which is secured to lower
idler gear 104 and the other to lower idler gear 140. Gear 140 is
rotatably journaled on stub shaft 144 rigidly connected to the
drive-side frame 2b and 22b of the feeder station 2 and delivery
station 22. Lower gear 140 meshes with the upper gear 142 rigidly
mounted on one end of cross-shaft 146, rotatably journaled in side
frames 22a and 22b in bearings 148, having a drive gear 150 rigidly
mounted on the opposite end thereof. Drive gear 150 meshes with
tape wheel gear 152 rigidly connected to the tape wheel axle
155.
From the foregoing it is readily apparent that power from motor 90
of printing tower 20 provides power through synchronizing links 136
and 138 to the tape wheel axle 155 of the delivery mechanism 22.
Power is supplied to the tape wheel axle 154 of feeder mechanism 2
in substantially the same manner as will be hereinafter
explained.
It should be noted that crankplate 116 on the upper idle gear 106
is rotated 90.degree. with reference to crankplate 116 on lower
idler gear 104. The particular configuration causes lower link 132
to be most efficient as a torque transmitting member at the instant
that upper link 134 is least efficient and vice versa.
A modified form of means for connecting the synchronizing links to
synchronize rotation of printing cylinders is illustrated in FIG.
XXX.
Links 132' and 134' are pivotally connected to crankpins 128' and
128" which are circumferentially spaced 90.degree. apart about the
axis of printing cylinder 48'. Crankpins 128' and 128" are secured
relative to a crankplate 116' by crankarms 116a and 116b. The
crankplate 116' is secured by suitable means such as bolts 120' to
the cylinder 48'. A support arm 116c secured to a side frame is
employed to support the outer end of the crankshaft assembly.
The gearing is such that the speed of sheet 5, carried by gripper
bar 8 of sheet transfer mechanism 10, is equal to the surface speed
of the blanket cylinders 48 so that no slippage occurs as sheet 5
passes through the printing nip 50n.
A cover 117 is bolted or otherwise rigidly secured at its opposite
ends to the drive side 2b and 22b of the printing press and extends
longitudinally thereof. Cover 117 extends outwardly from the press,
forming a protective guard around links 132-138, crankplates 116
and gears 100, 102-110. Additional covers 31a serve as windshields
for sheets 5, preventing movement of air currents about the sheet
which would cause the sheet to wrinkle or flutter as it passes
through the system.
SHEET TRANSFER MECHANISM
The sheet transfer mechanism, hereinbefore briefly described,
includes tape wheels 12 and 12b rigidly connected to tape wheel
axles 154 rotatably journaled in the side walls 2a and 2b of feeder
station 2 and tape wheels 14a and 14b rigidly connected to tape
wheel axle 155 rotatably journaled in tape wheel hangers 156
adjustably secured to side walls 22a and 22b of delivery station
2.
Referring to FIG. X of the drawing, it should be noted that tape
wheel hangers 156 are rotatably secured to bearings 148 in which
cross shaft 146 is journaled. Hangers 156 allow the distance
between the tape wheel shafts 154 in the feeder station 2 and tape
wheel shaft 155 in the delivery station 22 to be adjusted for
regulating the tension in tapes 16a and 16b.
Hangers 156 are provided in the delivery station only. However, it
should be readily apparent that tape wheel axle 154 or 155 could be
supported in hangers 156 as desired.
As illustrated in FIG. IV, tape wheel axle 155 has a bushing 156a
rotatably journaled thereon, having outwardly extending lug 156b
rigidly connected thereto. A pre-load adjusting screw 156c is
hingedly connected to lug 156b by a pin 156d. A stationary block
156e is rigidly secured to the side wall 22b of delivery station 22
by bolts 156f while sliding block 156g is adjustably secured to the
side walls by bolts 156h through elongated holes. Guide pins 156i
extend through blocks 156f and 156g having springs 156j therearound
between said blocks. An adjusting nut 156k threadedly engages
adjusting screw 156c.
It should be readily apparent that tension in tapes 16a and 16b may
be adjusted or pre-loaded by rotating pre-load adjustment nut 156k
relative to block 156g. While it is comtemplated that tapes 16a and
16b will move in a smooth uniform fashion , springs 156j on guide
pins 156i are provided for absorbing excessive shock and to prevent
breaking of parts of the sheet transfer mechanism 10.
Springs 156j also serve as an expansion joint for the tapes 16a and
16b, eliminating thermal stresses which would result in the tapes
if axle 155 were rigidly anchored.
The distance between gripper bars 8 will ordinarily be equal to the
circumference of plate cylinders 38U and 38L. However, the gripper
bars may be positioned at distances equal to multiples of the
circumference of the plate cylinders if it is deemed expedient to
do so.
Tapes 16a and 16b may be of any length as long as the length of
each tape is equal to a multiple of the circumference of plate
cylinders 38U and 38L.
It should be noted that the use of the straight line sheet transfer
mechanism 10 allows individual printing towers 18 and 20 to be
unevenly spaced if it is deemed expedient to do so. Therefore, a
multi-color press could have individual printing towers arranged
with varying spaces therebetween providing great flexibility,
allowing the printing press to be installed in a building without
modification where it might be necessary to modify the building for
installation of a conventional printing press.
Referring to FIG. X, tape wheel axle 155 extends through slot 155a
in the operator-side side frame 22a of the delivery station 22
having tape wheel gear 152 mounted on the outside of the side
frame, allowing tape wheel axle 155 to be adjusted by the tape
pre-load adjustment nut 156k. Gear 150 on crankshaft 146 is also
mounted on the outside of the side frame meshing with tape wheel
gear 152.
It should be noted that adjustment of the position of axle 155
causes gear 152 to be moved about the center of shaft 146 thereby
maintaining gears 150 and 152 in meshing relation.
Delivery wheels 145 are rigidly connected to cross-shaft 146 by a
pin 145a, providing power for delivery station 22.
Tape wheel axle 154 in the feeder station is journaled in side
walls 2a and 2b thereof. Tape wheel gear 152, FIG. II, is mounted
on the inside of the side frame 2a of feeder station 2. Gear 150,
mounted on cross-shaft 146 of the feeder station, is also mounted
on the inside of the operator-side frame 2a in driving relation
with tape wheel gear 152.
Cross-shaft 146 on the feeder station 2 extends through the side
frame 2a of said feeder station 2 and has a cam plate 147 rigidly
secured to cross-shaft 146 outside of the side frame 2a, FIG. I. A
stub shaft 147a is mounted on the outside of the side frame 2a of
feeder station 2 which has a bell crank 147b rotatably mounted
thereon. Cam follower 147c is rotatably journaled on bell crank
147b in rolling contact with cam plate 147. A second bell crank
147e is rigidly connected to actuator shaft 147d of swing gripper
mechanism 6 of feeder station 2. An adjustable link 147f connects
the lower ends of first bell crank 147b and second bell crank 147e
while a spring 147g, connected to the upper end of bell crank 147e,
urges said bell crank in a counter clockwise direction. It will be
apparent that spring 147g acting through bell crank 147e, link 147f
and bell crank 147b urges cam follower 147c toward the face of cam
plate 147. Cam 147 and related linkage is a means for delivering
power to feeder station 2 from drive motor 90 of printing towers 18
and 20.
As hereinbefore pointed out, feeder station 2 and delivery station
22 may be individually powered, if it is deemed desirable to do so.
Synchronizing links 136 and 138 would then function in exactly the
same manner as synchronizing links 132 and 134 for maintaining
individual components of the sheet transfer mechanism 10 in
synchronization with the components of individual printing towers
18 and 20.
As best seen in FIG. I and II of the drawing, each tape 16a and 16b
is an endless flexible conveyor having sufficient tensile strength
so that no appreciable stretch or lineal deformation results within
the range of forces applied thereto in its present application.
Tapes 16 may be constructed of any suitable material such as a
single strand steel tape, a multiple strand cable, or belt.
However, a steel tape is utilized in the particular embodiment
shown in the drawing. Tape 16a is carried about tape wheels 12a and
14a journaled on one side of the printing press while a second tape
16b is carried about tape wheels 12b and 14b journaled on the other
side of the printing press.
Each tape wheel 12a, 12b, 14a and 14b has V-blocks 158, FIGS. VI,
IX and X, radially spaced adjacent the circumference thereof. Each
V-block 158 has a key 160 extending outwardly from one face thereof
which is complementarily received by key way 162 in the tape
transfer wheel 14b in FIG. VI. V-block 158 is adjustably secured to
the tape transfer wheel by bolts 164 extending through elongated
holes 168 in V-block 158 to threadedly engage the transfer wheels.
A support block 170 is secured to the tape wheels adjacent V-blocks
158 by bolts 172 and has an adjusting screw 174 extending
therethrough. V-blocks 158 may be adjusted on the tape transfer
wheels by loosening bolts 164, allowing movement of the V-blocks
158 by rotation of adjusting screw 174. When the desired position
is attained bolts 164 and jam nut 176 on adjusting screw 174 are
tightened, thereby rigidly connecting the V-block to tape transfer
wheels. V-blocks 158 are mounted on tape transfer wheels 12a, 12b,
14a and 14b in the same manner.
Each gripper bar assembly 8 includes a support bar 178 rigidly
connected to tapes 16a and 16b by any suitable means such as
locating pins 180, FIG. VII. Heads 182 of locating pins 180 are
received by peripheral recesses 184 in each tape wheel 12a, 12b,
14a and 14b. Each support bar 178 has outer guide rollers 186a and
186b and inner guide rollers 188a and 188b rotatably mounted on
each end thereof. Each guide roller is mounted on axle 190 of
support bar 178 which has a bushing 192 rotatably mounted thereon
held in proper position by thrust washer 194 and a jam nut 196. A
set screw 198 is provided in jam nut 196 to prevent loosening of
jam nut 196.
An actuator shaft 200 is rotatably mounted in backup plate supports
202 which are welded or otherwise rigidly connected to the support
bar 178.
A backup plate 204 is rigidly connected by bolts 206 to backup
plate supports 202 and extends transversely between tapes 16a and
16b, which are spaced apart, in substantially parallel relationship
to support bar 178 and actuator shaft 200.
A plurality of conventional gripper finger support assemblies 208
are rigidly connected to actuator shaft 200 in spaced apart
relation throughout the length thereof. A gripper finger 210 is
rigidly connected to each gripper finger support assembly 208 by a
cap screw 212.
A torsion spring 214 is positioned about and connected between
actuator shaft 200 and the backup plate support 202, applying
torque to actuator shaft 200 to provide a substantial force,
causing pin 200a on shaft 200 to be maintained in engagement with
actuator shaft stop 200b extending outwardly from backup plate
support 202 to grip a sheet of paper 5 between gripper fingers 210
and backup plate 204. As best seen in FIG. VIII, compression spring
209 urges the gripper finger support assembly 208 and shaft 200 in
a counter clockwise direction. Torsion spring 214 overcomes the
forces exerted by compression springs 209 and urges pin 200a in a
clockwise direction into contact with stop 200b.
It is very important that sheet 5 will not slip relative to gripper
fingers 210 and backup plate 204 after the sheet has been gripped.
The spring constant of the torsion spring 214 and the number of
gripper fingers 210 necessary to accomplish this result may vary
depending upon the size and weight of the sheet 5 for specific
printing operations.
Cam followers 216 are rotatably journaled on actuator arms 218
adjacent tape wheels 12a, 12b, 14a and 14b. Arms 218 are rigidly
connected to actuator shaft 200. Cams 220 are fixedly secured by
bolts 222 to the tape wheel in such a relationship to the cam
followers 216 that rotation of the tape wheel will bring the cams
220 into contact with the followers 216, thereby rotating actuator
arms 218 and actuator shafts 200 against force exerted by the
torsion spring 214, causing gripper fingers 210 to rotate away from
backup plate 204. The exact position and configuration of the cams
220 may be varied in a specific operation whereby the gripper
fingers 210 will be rotated relative to backup plate 204 to grip a
sheet at the precise moment it is swung into proper position by
swing gripper 6 from the feeder mechanism 2 and to release the
sheet after printing has been accomplished thereon when the sheet
has been conveyed to the delivery mechanism 22.
While the specific description has been directed to tape wheel 14a
and 14b (FIGS. VI-X), it should be noted that tape wheels 12a, 12b
and grippers associated therewith have the same general
configuration and operate in substantially the same manner. The
tape carried gripper assemblies 8, rigidly connected to the endless
flexible conveyor tapes 16a and 16b by locating pins 180, grasp a
sheet of paper 5 from the swing gripper assembly 6 of the feeding
mechanism 2, move the sheet in a straight horizontal line to and
through the printing towers 18 and 20, release the sheet when it is
gripped by the delivery mechanism 22 and the gripper assemblies 8
return to the feeder mechanism 2 to pick up another sheet.
As best illustrated in FIG. IX of the drawing V-blocks 158 receive
the inner guide rollers 188 as tape wheels 12a, 12b, 14a and 14b
rotate, causing the tapes 16a and 16b and the gripper assemblies 8
to rotate therewith.
Inner tracks 224a and 224b and outer tracks 226a and 226b extend
longitudinally throughout the printing press at the upper and lower
ends thereof and are positioned to receive and guide the inner and
outer guide rollers 188a, 188b and 186a and 186b respectively,
thereby supporting the weight of each gripper bar 8 as it travels
between tape wheels 12a, 12b and 14a, 14b. As best seen in FIG. VI
of the drawing, the path of travel of the gripper bars 8 are
defined by the configuration of the opening between the inner track
224 and the outer track 226. One of the outer guide rollers 186b on
each support bar 178 has a groove 228 therein which receives and
rolls along an upwardly extending portion 230 of the outer track
226 on one side of the press. It should be readily apparent that
the gripper bars 8 will be guided by the outer track 226b because
lateral alignment is maintained by the groove 228 on the outer
guide wheel 186b while the inner track 224b above the inner guide
roller 188b prevents disengagement of the groove 228 from the
upwardly extending portion 230 of the outer track 226b.
As best illustrated in FIG. X, the other outer guide roller 186a on
each support bar 178 does not have a groove 228 thereabout. This
provides means for automatically compensating for thermal expansion
of support bar 178 because the guide roller 186a is free to move
laterally relative to the outer track 226a.
While guide tracks 224 and 226 are shown to be straight and
horizontal in FIG. IV, it should be readily apparent that the
tracks may be inclined or curved to conform with any desired
configuration if it is deemed expedient to do so. I anticipate the
use of the above described continuous gripping tape controlled
gripper bar 8 with tracks curved or inclined in a vertical or
horizontal plane for controlling the path of a sheet through a
printing press regardless of the geometric configuration of
individual printing towers and the components thereof.
Sheet 5, accelerated by conventional swing gripper assembly 6, is
gripped firmly along its leading edge by the tape carried gripper
bar assemblies 8 while the remainder of the sheet is
aerodynamically supported and floated on air to the first printing
tower 18.
Sheet transfer mechanism 10 hereinbefore described causes the sheet
5 to travel along the path of least resistance, thereby causing the
sheet to attain a position in a plane parallel with its direction
of travel.
Shaping of the outside of an object to provide as little air
resistance as possible is desirable in the design of objects which
are to travel fluently through the air. However, even well-designed
streamlined objects have drag caused by skin friction, causing a
boundary layer of air adjacent the surface of the object to move
with the object.
Moving air pushes up against flat surfaces held at an angle to the
direction of air flow and therefore surfaces moved through the air
are pushed upward by the force of air against their under surfaces.
The sheet being held along its leading edge, with the remaining
portion unsupported, is curved progressively downwardly due to the
weight of the unsupported length of the sheet. This shape produces
an air foil and consequently when the sheet is pulled forward along
its leading edge the air moves faster across the top of the sheet
than beneath it. The pressure of the fast moving air is, therefore,
less above the sheet than beneath it and accordingly the sheet will
be lifted along its unsupported length. It should be apparent that
the flexible sheet, suspended at its leading edge in gripper bar
assemblies 8, will attempt to achieve an equilibrium position due
to the upward force of air on the lower portion of the sheet and
also because of the low pressure air above the sheet, resulting
from the air foil when the sheet is curved.
It should be noted that lift of an air foil is proportional to the
square of the air speed. Therefore, even at relatively low printing
speeds adequate lift is provided for positioning the sheet in a
plane parallel to its direction of travel. The air pressure acting
upon the sheet lifts the unsupported surface of the sheet, coupled
with laminar flow of air along its surfaces, allows the sheet to
glide swiftly and smoothly from one printing station to
another.
The leading edges of the support bar 178 may be of any
configuration deemed expedient for reducing air turbulence along
the sheet or to increase lift if sufficient lift is not
accomplished at very low air speeds for heavy weight sheets. Slots
or openings in the support bar near the leading edge of the sheet
may be incorporated into the gripper bar assembly for directing air
currents across the sheet 5.
In the form of the device illustrated in FIG. XXXIV a pipe 178x is
connected to a suitable source of pressurized fluid, such as an air
compressor (not shown). Pipe 178x communicates with lines 178y
having outlet nozzles 178z positioned to direct air upwardly
against lower surfaces of sheets 5. The velocity of air jets is
controllable by suitable valving (not shown) to exert lifting force
upon the sheets and to minimize sheet flutter.
In FIG. XVII of the drawing, the sheet 5 is shown as the gripper
bar assembly directs the sheet into relation with the blanket
cylinders 48U and 48L for beginning the printing cycle.
Referring to FIG. XVIII of the drawing, the sheet is shown in
position just as the blanket cylinders 48U and 48L contact the
sheet. It should be noted that as the blanket cylinders contact the
sheet 5, additional forces are exerted upon the sheet, tending to
cause the sheet to lie in a plane perpendicular to the center line
between the opposing blanket cylinders. The sheet gripped at the
nip 59n between the blanket cylinders acts as a uniformly loaded
cantilever beam. The equation for the elastic curve of a uniformly
loaded cantilever beam is y = - w/24EI (x.sup.4 - 4L.sup.3 .times.
+ 3L.sup.4) where y equals the deflection of the beam, w equals the
unit weight of the material, E equals modulus of eleasticity, x
equals the distance from the unsupported end of the beam, and L
equals the length of the beam. Obviously, where x is equal to L at
the supported end of the beam, the deflection of the beam is
zero.
As best seen in FIG. XX of the drawing, the boundary layers of air
50p adjacent the surfaces of the blanket cylinders 48U and 48L and
the boundary layer of air 5a adjacent each side of the sheet 5 are
compressed as any given portion of the sheet approaches the nip 50n
between the blanket cylinders. Pressure wedges 50w are formed above
and below the sheet 5, also contributing to hold the sheet straight
out and away from the printing cylinders in an equilibrium
position, substantially bisecting the cusp area C formed by the
converging curved surfaces of the opposing blanket cylinders,
immediately prior to entering the nip 50n where printing is
accomplished.
As best seen in FIG. XIX, after printing has been accomplished at
the nip between the blanket cylinders the gripper bars 8 strip the
paper from the surfaces of the inked blanket cylinders 48U and 48L,
causing the sheet 5 to bisect the cusp C, and carries and directs
the sheets to the next printing tower.
From the foregoing it should be apparent that I have developed a
novel sheet transfer mechanism which utilizes natural phenomena for
aerodynamically supporting a sheet to and through successive
printing towers wherein the sheet travels along the line of least
resistance.
In view of the fact that sheets 5 are continuously gripped by
spaced grippers 210 mounted on a single gripper bar 8 from the
moment the sheet leaves feeder mechanism 2 until the moment it is
released at delivery mechanism 22, I anticipate the use of the
above described sheet transfer mechanism with a feeder which feeds
two sheets of paper simultaneously whereby the two sheets may be
gripped and carried through the successive printing towers wherein
printing will be accomplished on one side of each sheet
simultaneously or printing may be accomplished on both sides of a
single sheet simultaneously. Operation of the sheet transfer
mechanism in this manner will allow the printer who does not wish
to print on both sides of the sheet to run two sheets
simultaneously through the perfecting printing towers, thereby
utilizing the perfecting advantage while printing on one side of
the sheet, thereby doubling production for a job requiring the
printing on one side of a sheet.
A modified form of apparatus employed for indexing tapes 16a' and
16b' relative to tape wheels 14a' and 14b' and guide tracks 224'
and 226' is illustrated in FIGS. XXXI and XXXII.
Tape wheels 14a' and 14b' have projections, such as tooling balls
14t, secured in spaced apart relation about the periphery thereof.
As best illustrated in FIG. XXXII, tooling ball 14t has a threaded
shank 14s secured in a threaded aperture 14u through disc 14v. Disc
14v is secured in socket 14w, formed in the periphery of wheel 14b,
by bolts 14x.
Tapes 16a' and 16b' have spaced apertures 16t formed to receive
tooling balls 14t for positively indexing the gripper assembly 8'
relative to wheel 14b'.
As best illustrated in the form of the device illustrated in FIGS.
XXXI and XXXIV guide rollers 186a' and 186b' rotatably secured to
support bar 178' of gripper assembly 8', have flanges 228' formed
adjacent the inner edge thereof to engage tracks 224a', 224b',
226a' and 226b'. Rollers 186b' are mounted to permit movement
thereof longitudinally of support bar 178' and are urged outwardly
by springs 178". It should be apparent that flanges 228' are urged
into engagement with the respective guide tracks maintaining
lateral register of sheets 5 while permitting thermal expansion of
the gripper bar assembly 8'.
Printing cylinders 48', illustrated in FIG. XXXIV, of each printing
couple 18 and 20 are adapted to form an unobstructed passage
permitting movement of gripper assemblies 8' from the feeder
station to the delivery station without engagement with structural
members other than tracks 224a', 224b', 226a' and 226b', said
tracks directing the gripper assemblies 8' along a path having no
abrupt changes in direction. The tracks are preferably
substantially straight or uniformly curved to minimize abrupt
changes in speed and direction of the mass of the gripper
assemblies 8'. Changes in speed or direction would impart periodic
changes in the tension in tapes 16a' and 16b' and consequently
disturb register since exact correspondence of images printed at
each printing tower 18 and 20 must be constantly maintained for
quality multicolor printing.
The above description of a sheet transfer mechanism and the
mechanism for individually driving printing towers 18 and 20 has
been limited to printing towers capable of printing on both sides
of a sheet simultaneously. It should be noted, however, that the
above description is intended only to illustrate one suitable
embodiment of the invention. Obviously, the use of perfecting
printing toweres is not a prerequisite to success of the sheet
transfer mechanism 10 or the drive mechanism which I have
developed.
The perfecting printing towers, which have been described and
illustrated in the drawing, may be utilized for printing on one
side of a sheet, if it is desirable to do so, by simply removing
the plate 40 from one of the plate cylinders 38.
Individual printing towers 18 and 20 may be adapted to print on one
side of a sheet by merely eliminating one of the plate cylinders 38
and substituting an impression cylinder for one of the blanket
cylinders.
The straight through and continuous sheet transfer concept of
offset printing hereinbefore described does not require that the
sheet remain in a plane perpendicular to a line between the centers
of the printing cylinders. Likewise, it is not necessary that the
center of opposing blanket cylinders be vertically one above the
other. The term "straight through" merely distinguishes the concept
of the present invention from a sheet transfer mechanism of
conventional printing presses wherein a sheet is fed serpentine
fashion through the press.
Although multiple printing towers have been shown and described,
the concept of the present invention may be utilized with a press
having a single station for printing on one side or on both sides
of a sheet.
PRIMARY INKER
Primary inker 32, best seen in FIGS. V, XXII and XXV, includes an
ink reservoir 232 which forms a receptacle for ink 234. The ink
reservoir 232 is defined by a plate 236 extending between side
plates 237. Plate 236 is detachably secured to a substantially
semi-circular shaft 238 which is rotatably journaled adjacent its
opposite ends in adjustment eccentric 240 in self-aligning bushing
240a carried in bracket 240b, secured by bolts 240c to mounting
plate 33, detachably secured to side frames 26 and 28. A doctor
blade 239 is bolted, or otherwise detachably secured, on the shaft
238 adjacent a lower edge of the plate 236.
Adjustment 242, consisting of a screw 242a, having right-hand
threads at one end thereof and left-hand threads at the other end
thereof, threadedly engages rod eyes 242b at each end thereof. One
rod eye 242b is pivotally connected to shaft 238 by pin 242c, while
the other rod eye 242b is pivotally connected to the mounting plate
33 by pin 242d.
A resilient surfaced ink transfer roller 244 is rotatably journaled
in bushings 250 extending through side frames 26 and 28 in a
position adjacent the ink reservoir 232 and defines one side
thereof. Doctor blade 239 extends outwardly from the surface of
shaft 238 whereby the radius from the center of the shaft 238 to
the edge 239a of the doctor blade 239 is greater than the radius of
the shaft 238. It should be readily apparent in FIG. XXII of the
drawing that the adjustment screw 242 may be rotated for adjusting
the pressure between the edge 239a of the doctor blade 239 and the
surface of the ink transfer roller 244.
As ink transfer roller 244 rotates through the ink 234 downwardly
toward the doctor blade 239 a metered film of ink 244a adheres to
the surface thereof. The function of the adjustable doctor blade is
to meter or regulate the ink film thickness. Therefore, the doctor
blade 239 is a coarse metering device for measuring ink
distribution to the transfer roller 244.
Eccentric 240 is a means for adjusting the distance between the
center of shaft 238 and the center of ink transfer roller 244; and,
therefore, is also a means for adjusting the pressure between the
edge 239a of doctor blade 239 and the surface of transfer roller
244. Uneven adjustment of eccentrics 240 at opposite ends of shaft
238 adjusts the thickness of ink film 244a laterally along the
length of roller 244. After lateral distribution has been attained,
adjustment screw 242 is utilized to vary the thickness of film 244a
while leaving lateral distribution undisturbed.
Applicator roller 246 is in rolling pressure contact with transfer
roller 244. Consequently, the ink film 244a will be split,
according to the theory commonly referred to as the equal split
theory, whereby ink film 244b on the ink transfer roller 244 and
the ink film 246a on the applicator roller 246 will be of
substantially the same thickness.
Applicator roller 246 is also in rolling contact with the raised
ink pad 44 on the plate cylinder 38, thereby resulting in a split
of the ink film 246a into film 246b on the applicator roller 246
and a film 44a on the ink pad 44. It should be noted, as heretofore
pointed out in the description of the plate cylinder 38, that
applicator roller 246 applies ink to the raised ink pad 44;
however, plate 40 which is not raised does not contact applicator
roller 246. Consequently the primary inker 32 is in contact with
and applies ink only to the raised ink pad 44 and not to the plate
40.
The applicator roller 246 and transfer roller 244 are geared
together, as will be hereinafter explained and consequently rotate
at the same speed while the gearing is such that plate cylinder 38
may rotate at a different speed. By increasing or decreasing speed
of rotation of the applicator roller 246, the thickness of the ink
film 44a may be varied. The thickness of the ink film 44a,
therefore, regulated through a coarse adjustment by varying the
pressure of doctor blade 239 on the transfer roller 244 while fine
regulation is achieved by varying the surface speed of the
applicator roller 246 relative to the surface speed of ink pad
44.
As best seen in FIG. XXV, ink transfer roller 244 is rigidly
mounted on shaft 248 which is journaled in bushing 250 in the side
frames 26 and 28 of each printing tower 18 and 20. Shaft 248
extends through the operator-side side frame 26 and has a gear 252
rigidly connected thereto which meshes with and is driven by gear
254 rigidly secured to the shaft 256 of a variable ratio gear box
258 which is driven by conventional power take-off means
synchronized to press speed.
From the foregoing it should be apparent that while speed of
transfer roller 244 is variable, once a desired ratio of speed of
the transfer roller 244 relative to the speed of the plate cylinder
has been established, thereby regulating the ink film 44a at a
desired thickness, changes in the speed of the plate cylinder 38
will result in a corresponding change in the speed of the ink
transfer roller 244 and applicator roller 246, thereby maintaining
a desired thickness of the ink film 44a.
A hanger 260 is pivotally mounted on bushing 250 and supports an
eccentric bushing 262 in the opposite end thereof, having a shaft
264 on which the applicator roller 246 is mounted. Hanger 260 is
rotated by an actuating cylinder 261 against a positive adjustable
stop 261a, thereby controlling contacting pressure between the ink
pad and applicator roller 246. Timing gears 265 and 266 are mounted
on shafts 248 and 264 respectively whereby rotation of the
applicator roller 246 is imparted by rotation of the transfer
roller 244.
The particular modification of the primary inker allows the
transfer roller 244 and the applicator roller 246 to rotate in a
driving relationship at substantially the same surface speed,
having a speed determined by the variable ratio drive gear box 258.
This allows applicator roller 246 to slip relative to ink pad 44,
furnishing a fine metering device for precisely regulating the
thickness of the ink film 44a.
If it is deemed more desirable to do so, timing gear 265 may be
placed on the plate cylinder 38 thereby causing the applicator
roller 246 and the plate cylinder 38 to rotate in a driving
relationship. This also allows a fine regulation of the film
thickness 44a by slipping transfer roller 244 relative to
applicator roller 246. In this case the applicator merely serves as
an idler.
Although the transfer roller is shown and described with applicator
roller between it and the plate cylinder 38, it should be
understood that if the primary inker were placed on the other side
of the plate cylinder, an applicator roller 246 would be
unnecessary and transfer roller 244 would directly contact the
raised ink pad 44.
Utilization of the ink pad 44, the surface of which is raised above
the plate surface 40, eliminates the requirement for oscillating
the applicator roller away from the plate as the plate approaches
this roller. Oscillation would necessarily be required if ink pad
and plate were on the same level so that only the applicator roller
contacts the ink pad surface.
As best illustrated in FIG. XXXIII, a bride roller 246b, positioned
to transfer ink from the ink coated applicator roller 246 to form
roller 296 of the secondary inker, is employed if insufficient ink
is delivered to the form rollers 290-296 by ink pad 44 to prevent
one turn roller streaks.
In the form of primary inker illustrated in FIG. XXXIII, a roller
246t is employed in rolling contact with applicator roller 246.
Dual ductor rollers 244m and 244n are rotatably secured to an
oscillating arm 244p which is moved by a cam 244r causing surfaces
of ductor rollers 244m and 244n to alternately contact surfaces of
transfer roller 244 and roller 246t. The rate of rotation of cam
244r, preferably driven by the press determines the rate of
oscillation of rollers 244m and 244n. Transfer roller 244 is driven
by a variable ratio gear box as hereinbefore described such that
the speed of applicator roller 244 is changed linearly or
nonlinearly with changes in press speed. The speed ratio may be
manually adjusted to provide optimum ink coverage at any press
speed.
In the lower primary inker an additional roller 246t is positioned
between roller 246t and applicator roller 246 to maintain
directional rotation of the rollers.
Instances in which it is not deemed expedient to utilize the raised
ink pad, ink pad 44 may be lowered thereby causing the outer
surface of the ink pad to be the same radial distance from the
center of plate cylinder 38 as the radial distance from the center
of the plate cylinder to the outer surface of the plate 40. If the
ink pad 44 is not raised, applicator roller 246 may be mounted on a
shaft 272, thereby then acting as an oscillating roller, as shown
in the modified form of FIG. XXVI. A rotatable cam 276, geared to
the press drive, is provided for alternately shifting the
applicator roller 246 between the transfer roller 244 and the ink
pad 44. Bell crank 270 carries a cam follower 274 on the lower end
thereof and such follower is spring urged into contact with the
surface of a cam 276 by spring 278. It will be apparent that as the
larger radius 276a of the cam 276 contacts the cam follower 274 the
applicator roller 246 will be pushed into pressure contact with the
ink pad 44 and that when the cam follower 274 engages the reduced
radius 276b of the cam 276, the spring 278 will push the applicator
roller 246 into contact with the transfer roller 244. Thereby the
applicator roller 246 alternately contacts the ink pad 44 and the
transfer roller 244 to transfer ink from the transfer roller 244 to
the ink pad 44.
The applicator roller 246 is in pressure contact with transfer
roller 244 when the plate 40 is in a position adjacent applicator
roller 246. As the ink pad 44 is rotated adjacent applicator roller
246, the said roller will oscillate onto the ink pad 44 to
replenish ink thereto.
The purpose of the ink pad 44 is to facilitate even distribution of
the ink film over form rollers of the secondary inker and to allow
time for recovery of the ink film on the forms after they have been
partially depleted of ink by the passing of the plate 40 thereover.
The ink pad acts as a ductor which is partially depleted of ink by
the passing of the forms, the ink being replenished by the primary
inker. The use of conventional keys on the rigid doctor blade 239
is not necessary under normal operating conditions. However, it may
be deemed expedient, without deterring from the plate cylinder and
secondary inker arrangement, to utilize conventional keys or
adjusting screws 280 which are positioned in spaced apart relation
along the length of a conventional ink fountain doctor blade 282
for varying the pressure at particular locations along the length
of the blade with respect to transfer roller 244. Such a result may
be accomplished utilizing a conventional blade support assembly of
the type shown in FIG. XXVI for distributing ink over ink pad
44.
SECONDARY INKER
Referring to FIGS. V, XXII, XXIII and XXIV of the drawing, the
secondary inker, generally designated by numeral 34, includes a
plurality of form rollers 290, 292, 294 and 296 rotatably journaled
in eccentric 300 adjustably secured to form roll hangers 290a,
292a, 294a and 296a. Cap screws 300a, extending through a threaded
opening in an outwardly extending portion of each form roll hanger
290a, 292a, 294a and 296a, may be loosened, allowing rotation of
the eccentrics 300 by inserting a pin wrench into holes 300b in
each eccentric bearing 300, thereby adjusting pressure between each
form roller 290 through 296 and vibrator rollers 306 and 310.
Eccentric bushings 262 in the primary inker are similar in
construction to bearings 300 in the secondary inker.
Ink is fed to the ink pad 44, as hereinbefore described, by the
primary inker 32. The ink film 44a on the ink pad 44 is distributed
over form rollers 290 through 296, each having a resilient ink
receptive surface. The vibrator rollers 306, 308 and 310, usually
metal, and having a smooth ink receptive surface, impart a smooth,
churning action to the ink film on the said form rollers to
minimize irregularities that may form in the ink film thereon. The
ink film transferred from the pad 44 to the forms must go through
this experience prior to being applied to the plate 40. Vibrator
rollers serve not only to laterally smooth ink films on the form
rolls but also serve as momentary storage rolls replenishing form
rolls of ink removed therefrom until the ink storage pad can fully
recharge the form roll at the beginning of the inking cycle. They
also serve to drive form rollers at press speed, especially when
forms are in plate gap areas.
Vibrator rollers 306 and 310 are mounted on shafts 312 and 314
respectively and when rotated are translated axially by
conventional vibrator boxes 316 which use a worm, worm gear and cam
linked to the inker or press frame for providing translating
motion.
Each form roll 290 through 296 is rotatably journaled on separate
form roll hangers 290a, 292a, 294a and 296a respectively which are
rotatably journaled on sleeves 311 and 313 around the shafts 312
and 314 of vibrator rollers 306 and 310. Each form roll hanger
292a-296a is adjustably secured to actuator plate 304 by bolt 298b
in an elongated slot 298c whereby pressure between each form roller
and the plate cylinder 38 may be adjusted. To vary the pressure,
bolt 298b may be loosened whereby the form roller hangers 292a-296a
may be pivoted by turning adjusting screws 298d rigidly secured to
the actuator plate 304 and block 298e. From FIG. XXII of the
drawing, it is apparent that tightening adjustment screw 298d will
rotate form roller hanger 292a-296a and consequently the form
roller toward plate cylinder 38. When proper pressure is achieved,
bolt 298b may be tightened, locking the form roller in the desired
position.
Actuator plate 304 is pivotally mounted and rotates about shaft
312. Actuator cylinder 318 may be utilized for throwing the
secondary inker 34 on or off. In FIG. XXII of the drawing it should
be apparent that retraction of the piston rod of cylinder 318 will
rotate actuator plate 304, causing form rollers 292, 294 and 296 to
be separated from the surface of plate cylinder 38.
Multiple form rollers serve to smooth out the layer of ink to the
plate 40 and multiple diameters serve to minimize any visible trace
of one revolution pattern between the rollers and the plate.
Vibrator roller 306 is driven by timing belt 305 on the drive side
of the press and timing belt 307 on the end of shaft 312, connected
to vibrator roller 306, transmits motion to vibrator roller 310.
Roller 308 is a self-actuating vibrator and serves to connect
roller 292 to 294. Gearing is selected so that all rolls of the
secondary inker travel at substantially the same surface speed as
the plate surface.
From the foregoing it should be readily apparent that I have
developed a new and novel inking system comprising a primary inker
which delivers a regulated ink film 44a to ink pad 44 of plate
cylinder 38, which in turn is transmitted to form rollers 290-296
and subsequently to plate 40 attached to plate cylinder 38. Because
the length of the ink pad is made equal to, or greater than, the
circumference of the largest form roll, all form rolls turn at
least one revolution on the pad and become fully replenished of ink
after contact with the plate.
DAMPENER
Dampener 36 includes a reservoir 330 for dampening fluid having a
resilient covered metering roll 332 rotatably submerged therein
which is in rolling pressure contact with a chrome-plated
hydrophilic transfer roll 334 which is also in rolling pressure
contact with form roll 290 for providing dampening fluid thereto.
Dampener 36 is preferably of the type disclosed in my U.S. Pat. No.
3,168,037, issued Feb. 2, 1965, entitled "Means for Dampening
Lithographic Offset Printing Plates."
Dampener actuator cylinder 336 is connected to the metering and
transfer roller hanger 338 which is pivotally mounted at the
centerline of metering roller 332. The form roll hanger 290a which
supports form roll 290 is connected to the hanger 338, supporting
chrome-plated transfer roller 334 by a turnbuckle 338. Referring to
FIG. XXII, it should be apparent that actuation of cylinder 336
rotates hanger 338 and hanger 290a, thereby separating form roller
290 from plate cylinder 38. The link is so positioned that the
transfer roller 334 also separates from form roller 290 as cylinder
336 is actuated.
The dampener drive is individually driven and controlled. The drive
is variable speed with controls at each station and remote controls
at a console or master station, and speed indication (which
indicates) moisture transfer) and trim controls at the delivery end
of the printing system. However, other types of conventional
dampeners could be employed.
HYDROSTATIC BEARER
As hereinbefore pointed out in the description of the plate
cylinders 38 and the blanket cylinders 48, the massive bearers
which are universally used to prevent vibration of the plate
cylinders and the blanket cylinders when the cutaway portions
therein come into rolling contact have been eliminated. As best
seen in FIGS. XI-XVI of the drawing, a hydrostatic bearer bearing
46 is utilized for radially encompassing the shaft 38a at each end
of each plate cylinder 38 and each blanket cylinder 48 in the side
walls 26 and 28 of each printing tower 18 and 20.
Each hydrostatic bearer bearing 46 consists of a bushing 27, 27a,
29 and 29a which may have inside and outside diameters either
concentric or eccentric, depending upon which cylinder is journaled
therein. Bushing 27a and 29a, in which the upper and lower blanket
cylinders 48U and 48L are journaled, are eccentric as hereinbefore
described and rotated by the throw-off mechanism.
Each bushing 27, 27a, 29 and 29a has a multiplicity of recessed
areas 344 cut away from the inner surface thereof as best seen in
FIGS. XIII-XVI. While any number and any configuration of recesses
may be utilized which provides the best result for a specific
situation, depending upon the size and loading of the cylinders,
the particular embodiment illustrated in the drawing consists of
four substantially rectangular indentions in the inner face of each
bushing 27, 27a, 29 and 29a which are equally spaced and
diametrically opposed. Each recessed area 344 has an inlet port 346
centrally located therein which communicates with a flexible branch
line 348. Each branch line 348 has a pressure gauge 340 and a valve
352 mounted therein, whereby the pressure and flow rate of oil to
each recessed area 344 may be closely regulated. Branch lines 348
communicate through a suitable connection 356 with a trunk line 358
which in turn communicates through a suitable connection 360 with a
supply line 362. A pressure gauge 364 and valve 366 are positioned
in supply line 362 for regulating pressure and flow rate of oil
delivered by pump 368 from reservoir 370 through the supply line
362.
A modified form of the hydrostatic bearer is illustrated in FIGS.
XXIX and XXX wherein each bushing 27, 27a, 29 and 29a has a smooth
bore 372d formed in the outer end thereof. Each bore 372d has a
shoulder 372e at the inner end thereof against which a sleeve 372f
is positioned in abutting relation. Spaced recessed areas 344'
extend through walls of sleeve 372f and are positionable relative
to fluid inlet ports 346p to permit circulation of fluid as
hereinbefore described toward outlet ports 374p.
Provision of sleeves 372f allows fabrication of bushings 27, 27a,
29 and 29a in segments which can be modified or replaced without
replacing the entire assembly.
Sleeves 372f are secured in position by any suitable means.
However, in the preferred form the sleeve is secured by a shrink
fit.
From the foregoing it should be readily apparent that the pump 368
provides oil or other suitable hydraulic fluid under pressure in
regulated quantities through supply line 362 to trunk line 358
through the flexible branch line 348 to inlet port 346 of the
recesses 344.
Seals 372 are positioned in spaced apart relation in annular
grooves 372a, whereby oil delivered to recesses 344 is captured
therebetween. Outlet ports 374 are positioned in communication with
annular grooves 372a for removing low pressure oil from each
bushing through return line 376 communicating therewith. A heat
exchanger 378 is provided in return line 376 for cooling the coil
which has been circulated through each bearing 27, 27a, 29 and 29a.
Oil from the heat exchanger 378 is returned to reservoir 370,
thereby completing the cycle through the hydraulic system.
Additional check valves, pressure gauges, filters and the like may
be provided to solve problems encountered in specific
situations.
Inlet port 346 and outlet port 374 may be positioned in any
suitable configuration depending upon space requirements.
In view of the fact that the loading on the plate cylinders and
blanket cylinders is small compared to pressure maintained in the
vicinity of recesses 344, the hydrostatic bearer, hereinbefore
described, provides a very stiff bearing which is virtually free
from wear, having a starting torque which is negligible. Virtually
friction free rotation may be achieved, although the difference in
the outside diameter of the journal of the shaft and the inside
diameter of each bushing 46 is very slight, having clearances of a
few thousandths of an inch which results in a cylinder without
wobble and having sufficient stiffness to eliminate bearers
heretofore employed.
Bushings 27, 27a, 29 and 29a are very short in length relative to
the distance between side frames 26 and 28 relative to the journal
diameter of the cylinder ends. Therefore, exact alignment of said
bushings in opposite side frames is not necessary to prevent
binding between the journal and the bushing. Also closer fit of
bearing to journal can be accomplished, thereby increasing
stiffness, when narrow bearings are used because deflection of
journals 38a, 38b, 48a and 48b, when loaded, is negligible.
By utilizing large rigid journals on the ends of the printing
cylinders, by minimizing long widths, by using materials for both
journal and bearing having nearly equal thermal expansion
coefficients, and by preloading the journal in the center of the
bearing with a controlled pressure, oil flow rate, and temperature,
I have achieved virtually the ultimate in obtaining a very stiff,
long life, low starting torque self-aligning, totally enclosed
bearing which serves also as a hydro-bearer. I have disproved that
the rule of thumb used by the industry for determining bearing
clearances (0.001 inches/inch diameter) can be reduced
substantially to one-fourth (0.00025 inches/inch diameter) without
causing any adverse affects whatsoever.
I have eliminated not only bearers, but also problems relating
thereto, such as setting bearer pressures and forcing conventional
bearings and cylinder journals into an abnormal position which
contributes to cylinder fatigue, short bearing life and costly
maintenance.
Utilization of materials having equal coefficients of thermal
expansion, such as cast iron for bushings 27, 27a, 29 and 29a and
steel for journals 38a, 38b, 48a and 48b, results in expansion of
the hole in said bushings at the same rate of expansion as the
journals, thereby resulting in uniformity of allowance between
journal and bushing regardless of temperature increase or decrease
of the members.
The use of the hydrostatic bearers is especially important in the
press described herein, because it is important that wobble and
drag be reduced to a minimum in order to effect perfect registry,
controlled cutoff and inter-unit synchronization provided by this
improved press.
From the foregoing it should be readily apparent that I have
developed an improved printing press which is simple in design and
operation and offers high speed production while simultaneously
achieving the high quality. I have developed a multicolor
perfecting capability which includes a new combination of improved
components comprising a hydrostatic bearing, a load sharing and
inter-unit synchronizing system plus a new and improved ink
fountain, a novel plate cylinder and blanket cylinder having a
cooperative relationship for providing a uniform distribution of
the ink film for replenishing the ink, after each printing cycle,
in accordance with demands of the blanket cylinder where printing
is accomplished. A novel sheet transfer mechanism incorporated
herein eliminates numerous printing problems heretofore
encountered, while providing a sheet-fed printing press having all
the advantages of a sheetfed press and of a web-fed press in a
single unit which most effectively utilizes the improved inker in
the lithographic process.
The press is versatile in that it may be adapted for perfecting,
single side printing, or two sheets may be printed
simultaneously.
While any one of the improved components which I have developed may
be used individually or in combination for improving printing
presses heretofore developed, best results are accomplished by
combining the aforesaid improvements in a single printing press of
the type hereinbefore described.
OPERATION
Having described a suitable embodiment of my invention, a mode of
operation is as follows:
The sequence of operation will be described in five steps
comprising:
Step 1 -- make ready,
Step 2 -- primary inker "on,"
Step 3 -- dampener "on,"
Step 4 -- secondary inker form rollers "on," and
Step 5 -- impression "on."
Make ready procedure is substantially the same as that required in
the operation of conventional printing presses. Plates 40 must be
installed on plate cylinders 38 and blankets 50 must be installed
on blanket cylinders 48 with proper packing 38p and 48p under each
plate 40 and each blanket 50.
The reservoir of the primary inker 32 and dampener 36 must be
filled.
Certain initial adjustments must be made. The pressure between
metering roll 332, chrome transfer roll 334 and form roll 290 must
be adjusted to regulate the supply of dampening fluid to the plate,
providing uniformly distributed and regulated amounts of moisture
to the plate. The approximate speed ratio between transfer roll 334
and form roll 290 must be established for regulating the proper
dampening fluid film thickness to the plate.
The pressure between doctor blade 239 and transfer roller 244 of
the primary inker 32 must be adjusted for regulating the thickness
of film 244a. The approximate speed ratio between roller 246 and
plate cylinder 38 must be established for regulating the thickness
of ink film 44a on ink pad 44.
The pressure between form rolls 290 and 292 and vibrator roller 306
and form rollers 294 and 296 with vibrator roller 310 may be
adjusted for providing smooth distribution of ink film 44a over
said form rollers. Form rolls 290-296 and applicator roll 246
should be properly set to plate and ink pad respectively.
Printing impression pressure may be adjusted by varying the
pressure between each blanket cylinder 48 and its adjacent plate
cylinder 38, utilizing adjustment screw 82.
Sheet pressure may be adjusted for the specific thickness of stock
to be run, utilizing paper pressure adjustment 84.
A stack of sheets 4 is placed upon the skid of feeder mechanism 2.
Make ready is completed by starting the printing units, thereby
starting the sheet transfer mechanism 10 synchronized through links
136 and 138 with the individual printing towers 18 and 20, thereby
starting feeder 2 and delivery 22. When the printing units are
started all cylinders, the plate cylinders 38 and blanket cylinders
48, all form rolls, all vibrator rollers and the sheet transfer
mechanism are traveling at virtually the same surface speed. When
the inker and dampener reservoirs are full and the rollers are
rotating, step 1, make ready, is completed.
Step 2 of the operation, primary inker "on," is initiated by
actuating cylinder 261, causing roller 246 to be pivoted in contact
with ink pads 44 on plate cylinders 38. Ink film 44a builds up to
an equilibrium thickness according to the adjustment of ink
fountain doctor blade 239 and according to the speed of transfer
roller 246 relative to the speed of plate cylinder 38.
It should be noted that ink pad 44 is slightly raised relative to
plate 40 and consequently the primary inking transfer roller 246
contacts only the ink receptive storage pad 44 while clearing the
plate 40 as the respective cylinders rotate. Therefore, the plate
40 does not receive ink from the primary inker 32.
Step 3, dampener and first form roller of secondary inker "on," is
initiated by actuating cylinder 336, causing form rolls 290 to be
pivoted into contact with plates 40 on plate cylinders 38. The
fountain solution is now being distributed to the first inker form
rollers 290 and thence to the plate 40 and builds up an equilibrium
on the plate 40 according to the dampening metering roll setting to
the transfer roll and according to transfer roll's surface speed
relative to that of form roll 290.
It should be noted that form roll 290 contacts the ink pad 44 as
well as dampener transfer roll 334 and plate 40, thereby starting
the supply of ink to the remaining secondary inker rollers 292, 294
and 296 and to the plate 40. Fountain solution and ink is now on
the plate where lithography occurs. Plate 40 is cleaned in the
non-image areas and inked up in image areas. The remaining form
rolls of the secondary inker 34 are now ready to engage plate
40.
Step 4 of the operating sequence, secondary inker forms "on," is
initiated by actuating cylinder 318, causing form rollers 292, 294
and 296 to be pivoted into contact with plate 40. Each form roll
290-296 turns at least one complete revolution on the ink pad 44
prior to engagement with plate 40.
Multiple form rolls serve to smooth out the layer of ink to the
plate and multiple diameters serve to minimize any visible trace of
one revolution pattern between the rollers and the plate. Vibrators
306, 308 and 310 serve to laterally smooth ink films on the form
rolls and serve as momentary storage rolls, replenishing the form
rolls of ink removed therefrom until the ink storage pad 44 can
fully recharge the form roll at the beginning of the inking
cycle.
As hereinbefore explained, form rolls 292-296 are disengaged from
plate 40 and ink storage pad 44 when the secondary inker is off.
When the secondary inker forms are on they engage plate 40 and ink
storage pad 44. When the individual printing tower is off
impression, the blanket and plate cylinders are separated and the
blanket cylinders are separated. After a few revolutions of the
plate an equilibrium of ink and water is reached, keeping the
non-image area clean and maintaining a fixed quantity of ink on the
plate ready for transfer to the blanket 50 when the tower is placed
on impression for the printing cycle.
Step 5 of the cycle of operation is impression "on." A sheet from
stack 4 in feeder station 2 will be started through the press
manually. Blanket cylinders 48 go on automatically and
progressively when a sheet is detected at the proper place prior to
entering the first printing station. Absence of a sheet at a proper
place will stop the feeders and sequentially and progressively
throw off the blanket cylinders at each printing station as the
last sheet to be printed progresses through the system.
The first sheet 5 is detected by an electrical limit switch (not
shown). The electrical limit switch actuates throw-off cylinder 60
simultaneously moving the upper blanket cylinder 48U and the lower
blanket cylinder 48L into contact with plates 40 on the upper and
lower plate cylinders 38U and 38L and into contact with sheet 5 as
it moves between the blanket cylinders 48U and 48L. As the sheet
progresses to subsequent printing towers, the blanket cylinders
will be engaged in precise synchronization so that the blanket
cylinders are engaged to opposing blankets and their adjacent plate
cylinders at the proper time.
Absence of a sheet in its proper place prior to entering the first
printing station will cause the first printing station opposing
blanket cylinders to separate immediately after the last sheet
leaves the blanket nip 50n. Through synchronization, the following
printing stations blanket cylinders separate as this same last
sheet leaves the blanket cylinder nip of the respective towers. All
units will remain off until the feeding problem is corrected and
the feeder is manually started.
After the presence or absence of a sheet is detected the method of
blanket cylinder actuation is performed by electrical limit
switches, operating by cams synchronized with the system, which
operate selector valves, which in turn route oil or air pressure to
hydraulic or pneumatic cylinders 60. The cylinders operate a
mechanical linkage, hereinbefore described, which engages the
blanket cylinder when a sheet 5 is present or disengages the
blanket cylinders when a sheet is not present.
As blanket 50 is moved into contact with plate 40 and sheet 5, ink
is transferred from plate 40 to blanket 50 and offset to sheet 5.
The cycle of inking, dampening and printing with a continuous duty
inker and dampener now begins.
After an equilibrium of ink and water is reached on the plate 40
and, therefore, throughout the inking and dampening system, it
should be noted that upon going "on impression" any ink or water
quantity removed from the plate 40, caused by transfer to the
blanket 50 and thence to the sheet 5, is immediately replenished by
the continuous duty aspects of the inking and dampening system.
It should also be noted that ink removed from blanket 50 by the
sheet 5 is replenished by plate 40 while plate 40 is replenished by
form rolls 290-296 of the secondary inker 34. Ink or water removed
from forms 290-296 is replenished by the continuous duty dampening
system 36, ink vibrator storage rolls 306, 308 and 310 and ink
storage pad 44. Ink removed from storage pad 44 is replenished by
the continuous primary inker 32.
Form rolls 290-296 of secondary inker 34 are replenished by the ink
pad 44, presenting a fully recovered ink surface to the plate 40
after it has been depleted of ink by blanket 50. With each cycle of
plate cylinder 38, exactly the same amount of ink which is removed
from form rolls 290-296 is replenished.
Minute adjustments may be made at the beginning or during the
production run.
As the last sheet from stack 4 leaves feeder station 2 the
electrical limit switch will actuate throw-off cylinder 60, causing
the blanket cylinders of the first printing station to separate
immediately after the last sheet leaves the blanket nip. Subsequent
printing towers will be thrown off impression as the last sheet
passes therethrough.
As many towers may be added as may be desired, the two illustrated
being simply for illustration purposes. Therefore, as many colors
may be printed on one or both sides of the sheet as may be desired,
depending upon the number of towers.
Furthermore, any tower or the upper or lower section of any tower
may be rendered inoperative for printing simply by leaving the
plate off of the selected plate cylinder, in which instance the
blanket cylinder associated therewith would serve as an impression
cylinder only. Therefore the press may be selectively utilized for
printing on one or both sides of the sheet. Perfect registry and
cutoff is accomplished by virtue of the continuous sheet conveyor
system hereinbefore described.
It will be understood that other and further embodiments of the
invention may be devised without departing from the spirit and
scope of the appended claims.
* * * * *