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Патент USA US2117546

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May 17, 1938-
A. c. DOBROTH. .JR'
'
2,117,546
MULTICQLOR PRINTING
Filed Oct. 3, 1936
A/berf C‘. Dobror‘hJn
W
2,117,546
Patented May 17, 1938
PATENT OFFICE
UNITED STATES
2,117,546
MULTICOLOR PRINTING
Albert C. Dobroth, Jr., Louisville, Ky.
Application October 3, 1936, Serial No. 103,863
6 Claims.
(01. 101-174)
This invention relates to the art of sheet-fed
rotary machine printing and has Particular ap
plication to the printing of superimposed colored
press of campact construction, it follows that the
problem thus presented is peculiar only to this
speci?c process of printing.
inks upon various types of paper. Heretofore,
5 this method of printing has been adapted pri—
The present invention provides a solution to
these problems and has as an object the teaching
of a method for printing multicolor impressions
marily to the production of commercial prints in
large quantities or in job lots and as a result
the quality of the resulting work has been sub
ordinated to the necessities of rapid printing.
10 While'the three, four and ?ve color printing
methods of the present, as exempli?ed by con
temporary magazine covers, are largely con
ducted upon sheet-fed rotary machines, it is
found that certain disadvantages are present.
1.5
In order to secure a quality type of printed
product the characteristics of the paper, the ink
and the printing press must each be considered.
As a result of the demands for quantity produc
tion the presses are designed and operated for
maximum speeds and the ink frequently is un
2 O able to set or to partially dry between successive
impressions upon the paper. This then gives rise
to a lack of brilliancy and loss of detail in the
?nal product due to the middle tones of color
becoming too light or to the light tones of color
2 DI becoming ?attened or running together.
This problem, moreover, is accentuated by the
fact that the conventional paper used for maga
zine covers or the like is usually hard-sized. As
a consequence, the paper tends to take the ink
3O
on the raised portions of the paper grain, while
the minute depressions in the paper surface re
main more or less bare thus giving rise to a
grainy or “unsound” impression. In order to
avoid this, a slight dilution of the gravure ink is
Ci
sometimes made but this expedient gives rise
to a more or less mottled or granular effect par
ticularly in the darker tones. When the printed
paper is then examined under a microscope it
40 is found that dots constituting the image be
come indistinguishable in the darker middle
tones and shadows because the ink has piled up
irregularly and given a grainy effect.
Various ink drying expedients have been em
45, ployed upon sheet-fed rotary presses to overcome
these dif?culties, but have required the use of‘
complicated apparatus and have not met with
notable success.
In printing by means of web
rotary presses the above mentioned problem has
{,0 not been presented due to the fact that a com
pact machine with closely spaced printing rolls
is not employed in this process. Furthermore,
since the exact register of color required for pre
cision multicolor printing in quantities can be
55 secured practically only upon a sheet~fed rotary
with a sheet-fed rotary apparatus and charac
terized by the ?delity of color gradation upon
the resulting product.
>
i
A second object is the teaching of a method
for rapidly printing multicolor impressions upon
paper while insuring well rendered “high-lights"
and shadows in the resulting product.
Another object is the provision of sheet-fed
10'
rotary printing apparatus adapted to print
multicolor sheets of superior color gradation
without reducing the normal capacity of the ap
paratus.
A further object is the provision of improved
printing apparatus capable of being adapted to
existing sheet-fed rotary printing apparatus.
Other objects and advantages of the inven
tion will become more apparent when considered
in conjunction with the accompanying drawing
in which the ?gure illustrates one diagrammati
cal form of apparatus capable of carrying out
the invention.
As the description proceeds it will become evi
dent that the invention is adapted for conduct
ing the improved printing process either upon _
a special press designed primarily in accordance
with this teaching or upon a conventional in
stalled press to which the improved apparatus
herein disclosed may be applied. Consequently, it
is to be expressly understood that the accom
panying drawing merely shows on form which
the apparatus may assume and that the inven
tion is not to be limited solely to that particular
design of printing press.
Referring now to the drawing, a substantial 4
support means I has housed therein a large im- “
)
pression cylinder 2 provided with conventional
holding means (not shown) for securing against
the cylinder surface those sheets of paper which
are to be printed.
This cylinder is preferably provided with a
conventional covering material such as a tym
pan sheet which provides a backing for the
pressure exerted by the plate cylinders upon the
sheets of paper as they are printed. As will be
more fully disclosed hereinafter, this function
of an impression roll in the printing process is
of great importance in producing quality work
and the present invention has as an important
object the teaching of a means for independ
555
2,117,546
ently regulating the pressures applied to the
sheets at the critical printing steps.
which customarily is the yellow impression, plays
Housed within the support means adjacent the
upper portion thereof is a rotatable guide 3 sup
porting a conveyor means 4 and 5 adapted to
remove the printed sheets from the press after
the ?nal printing impression has been received.
the resulting work and that unless a thorough im
pregnation of the paper with ?delity of plate etch
A plurality of plate cylinders 6, 1, 8 and 9, each
of which is adapted to place a different color ink
10 upon the sheets of paper may be housed in the
support means 1.
Each of these cylinders co
operates with the impression cylinder 2 and is
adapted to print upon the paper sheets a predeter
mined color ink with a gradation of color accord
ing to the plate structure which they carry.
In certain apparatus now available the plate
markable brilliancy and. clarity of detail can be 10
obtained in the ?nal product.
i
The present invention provides a solution to
these problems and as shown in the drawing a
housing It] adapted to support a portion of the
printing apparatus is located adjacent the main
support means I and is a?ixed thereto by any suit
able securing arrangement.
A conveyor means ll brings successive sheets
of paper I2 to the usual intake cylinder l3 which
pression cylinder in this usual type of apparatus.
The unprinted sheets of paper entering the press
by means of a conveyor mechanism having an
intake cylinder are secured to impression cylinder
similar to that shown at 2 by holding means or
grippers and immediately pass under the several
plate cylinders in rapid succession meanwhile
receiving the several superimposed color ink im
pressions.
.
Due to the fact that such an apparatus is com
pact and can be operated at high speeds with con
sequent large quantity production and at the same
time give a superior register of impressions, nu
merous disadvantages of the apparatus and meth
, 0d of printing have been overlooked.
As before stated, the hard-sized paper cus
tomarily printed on sheet-fed rotary presses tends
to take ink chiefly upon the raised portions of the
paper ?ber. In order to impress the ink rapidly
into the pores of the paper, suf?cient pressure has
to be exerted by the initial plate cylinder to make
etched designs of the plate sufficiently clear.
This pressure, if excessive, forces the paper sheet
into the tympan sheet and causes disagreeable
raised
portions on the opposite side of the sheet
45
‘being printed which in turn results in a problem
when that side of the sheet is later printed.
Since the sheet therefore assumes an irregular
directs thev sheet to an auxiliary impression cyl
inder l5 spaced from and independent of the‘main
impression cylinder 2. Cooperating with the im
pression cylinder I5 is the initial plate cylinder
94 which impresses the initial color upon the
paper sheet. The sheet thus printed is trans
ferred from the auxiliary impression cylinder to
the main impression cylinder by means of a trans
fer cylinder 16.
Due to the arrangement thus provided the sheet
travels a substantially greater distance, in com‘- .
parison with present apparatus, from the ?rst
to the second plate cylinders and a commensu
rately greater time elapses between these_print—
ings with the result that the initial ink has su?i
cient time to set normally and to creep into the L2 LI
microscopic pores of the paper sheet before hav
ing other ink superimposed upon it. This factor
obviates the necessity for using excessive pressure
upon the initial plate cylinder in order to force the
ink rapidly into the paper and at the same time
results in a sheet having a primer coat of properly 49
distributed ink. The successive sheets then re
ceive the second ink impression from cylinder 9
and the remaining ink impressions from cylinders
8, ‘I and 6.
.4; Lit
Since the initial color impression thus applied ‘ '
has an opportunity to set upon the paper, the
surface, each of the succeeding plate cylinders
succeeding impressions may be made in rapid
succession and with closely regulated pressures.
9, 8, ‘I and 6 must be adjusted to provide a pres- '
As a consequence, very light frictional contacts ;.
sure commensurate with the pressure exerted by
the initial plate cylinder so as to lay the super
imposed ink in its proper place upon the initial
ink.
Consequently when all of the plate cylinders co
may be made upon the paper sheets by the later
printing cylinders and in this way clear detail
may be obtained and the “muddy” effect caused
by mixing of the inks under pressure may be
eliminated. Furthermore, the delicate gradation 5
of color required for well rendered “high lights”,
shadows and curved surfaces is also secured since
the etched plates on the later printing cylinders
‘operate with a single impression cylinder, the
superimposed ink impressions tend to pile up on
each other With excessive pressure and inter
mix thus giving rise to a “muddy” color in the
60 ?nal product.
This problem, moreover, is enhanced by the fact
that the ink does not have suflicient time to “set”
or to dry partially between the ?rst and succeed
ing impressions. With a compact sheet-fed ro
65 tary press running at a cyclic rate of 5000 sheets
per hour it is estimated that only one-?fth of ‘a
second or less elapses between the initial im
pression and the ?rst succeeding impression. The
recourse to auxiliary ink drying equipment by
70 itself has not been wholly satisfactory due par
tially to the fact that the use of a single im
pression roll requires the second and succeeding
plate cylinders to exert excessive pressures upon
the ?rst ink impression.
It has been found that the initial ink impression,
if
pression is properly made and at the same time the
ink can set su?iciently and the pressures of suc
ceeding impressions are properly adjusted, a re
a short distance from cylinder 9 in a location
20 and 9 which are shown as being adjacent the im
50
ing is made at this critical stage the quality of
the work invariably suffers. If the initial im
cylinder adapted to print the initial color is located
comparable to the locations of cylinders 6, .1, 8
30
an extremely important part in the quality of
are enabled to lay their ink with as light a pres
sure as is consistent with a sound impression.
While the structure as shown is designed to
print ?ve colors it will be apparent that a smaller
or larger number of color plate cylinders may
be provided without departing from the teachings
of the invention.
65
It will be noted that by following this teach
ing no loss in capacity of the apparatus is sus
tained. The successive sheets pass through'the
press with the same speed as before but travel
through a longer path between the ?rst and sec 70
ond plate cylinders. The location of housing 10
provides access to cylinders l4 and 9 for the usual
inking carriage and housing and necessitates no
change in design of the conventional apparatus
in this regard.
75
2,117,546
In the event that additional auxiliary drying
of the initial ink impression is desired, it is con—
templated that any suitable drying apparatus as
indicated diagrammatically at !1 may be in
stalled without departing from the teachings of
the invention.
Since the many advantages derived from this
improved process result primarily from the use
of an initial printing step which is separate from
10 the remaining printing steps, it is obvious that this
initial printing step becomes the critical phase
of the entire process. Numerous changes, there
fore, in the apparatus designed to carry out this
step will occur to the person skilled in the art.
15 The location of cylinder !4 so as to secure the
requisite path of movement of the sheet before
reaching cylinder 9 may be subjected to wide
variations. The adjustment of printing pressure
exerted by the plates of cylinder [4 against the
20 paper sheet will likewise be subject to variation
depending upon the texture of the paper and the
nature of the ink being used.
Since these changes may readily be employed
without departing from‘ the essentials of the in
25 vention, it is with the intention of including such
changes in the above disclosure as will occur to
one skilled in the art that,
I claim:
1. The process of printing three or more su
30 perimposed
color impressions upon separate
sheets of paper moving at a substantially con
stant rate of speed comprising, printing an initial
color impression upon a sheet at a point in its
path of movement relatively distant from the sec
35 ond color impression point and at a correspond
ingly large interval of time, printing a second
color impression upon the initial color impression
of the same sheet whereby the interval of time
elapsing between the ?rst and second impressions
is su?lcient to permit the initial ink to set and
to allow the second ink impression to form a well
de?ned color gradation thereupon and then print
ing a third color impression upon the previous
impressions and at a point in the path of move
ment of the sheet relatively near to the second
color impression point and at a correspondingly
small interval of time.
2. In the printing of three or more superim
posed color impressions upon each of a series of
50 consecutive sheets of paper moving at a substan
tially constant rate of speed, the method of form
ing Well-de?ned color gradations of the several
color impressions comprising, impregnating the
paper with an initial color ink at a point in its
55 path of movement relatively distant from the
second color impression point and at a corre
spondingly large interval of time in order to pro
vide a partially dry primer coat on the moving
sheets of paper prior to adding a different color
impression, printing a second color impression
upon the partially dry initial impression and then
printing succeeding superimposed color impres
sions at points in the path of movement of the
paper relatively close to the second color impres
65 sion point.
3. The improvement in the art of sheet-fed
rotary machine multicolor printing comprising,
printing an initial color at a point in path of
movement of the sheet relatively distant from
70 the second color impression point by means of an
3
initial pressure insuihcient to form substantial
depressions in the paper sheet, moving the sheet
through a time interval between the initial and
next' succeeding inking operations su?icient to
permit the initial ink to impregnate the pores of
the paper and to set upon the paper, applying a
second and different color ink upon the initial ink
by means of a pressure independent of the initial
printing pressure and then applying one or more
additional colors to the inked sheet at points 10
spaced relatively close to the second inking point
in the path of movement of the sheets.
4. The improvement in the art of sheet-fed
rotary machine multicolor printing comprising,
printing an initial color at a point in path of 15
movement of the sheet relatively distant from the
second inking point by means of an initial pres
sure capable of depositing the initial ink in con
formity to the plate etching but incapable of
forming substantial depressions in the paper 20
sheet, moving the sheet through a space between
the initial and next succeeding inking points
su?icient to permit the paper to take up the ink
in the form of a primer coat, superimposing a
di?erent color ink upon the primer coat by means 25
of a relatively light pressure independent of the
initial printing pressure, whereby clarity of detail
may be obtained in the printed product and then
superimposing a third color ink upon the previ~
ously inked sheet at a point in its path of move
30
ment relatively close to the second inking point.
5. A rotary printing apparatus adapted to print
three or more superimposed color impressions
upon separate sheets of paper moving at a sub
stantially constant rate of speed comprising, a
main impression cylinder, a plurality of color
plate cylinders spaced at approximately equal
intervals and at small distances apart and coop
erating with the main impression cylinder, a sep
arate impression cylinder spaced at a substan 40
tially large distance from the main impression
cylinder, an initial color cylinder cooperating with
the spaced impression cylinder, means to transfer
the sheets of paper from the spaced impression
cylinder to the main impression cylinder, means 45
to feed the unprinted sheets of paper to the
spaced impression cylinder and means to remove
the printed sheets of paper from the main im
pression cylinder.
6. A rotary printing apparatus adapted to
print three or more superimposed color impres
sions upon separate sheets of paper moving at a
substantially constant rate of speed comprising,
a main impression cylinder, a plurality of color
plate cylinders spaced at approximately equal
intervals and at small distances apart and coop
erating with the main impression cylinder, a sep—
arate impression cylinder spaced at a substan
tially large distance from the main impression
cylinder, an initial color cylinder cooperating 60
with the spaced impression cylinder, means to
transfer the sheets of paper from the spaced im
pression cylinder to the main impression cylin
der, auxiliary drying means located adjacent the
path of the paper sheet intermediate the im— 65
pression cylinders, means. to feed the unprinted
sheets of paper to the spaced impression cylin
der and means to remove the printed sheets of
paper from the main impression cylinder.
ALBERT C. DOBROTH, JR.
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