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SPECIFICATION
TITLE OF THE INVENTION
OFFSET ROTARY PRINTING MACHINE AND METHOD OF ADJUSTING
ANGLE OF PRINTING CYLINDERS
BACKGROUND OF THE INVENTION
(1) Field of the Invention
The present invention relates to an offset rotary-
printing machine and a method of adjusting angle of
imaginary oblique plane, which is inclined with imaginary
perpendicular plane being perpendicular to the moving
direction of a web suitable for the prevention of web
delamination.
(2) Description of the Related Art
An offset rotary printing machine, as shown in FIG.
13, supplies a roll of web (continuous paper) 10 from a
web feeder section 1 by an in-feed device 2, and prints
on the web 10 at a printing section 3, which comprises
a suitable number of printing units 7. The printed web
10 goes through a dryer section 51, a cooling section 52,
and a web pass section 53 and to a folding machine 6, in
which the folded web is made. In the case of multicolor
printing, the printing section 3 is provided with a number
of printing units 7 that corresponds to the number of colors
to be printed. Generally, offset rotary printingmachines
are able to print on both sides of the web at once.

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FIG. 14 shows the configuration of a printing unit
7 installed in a perfecting press through which the web
goes approximately horizontally. As shown in the figure,
the printing unit 7 comprises an upper printing unit section
7a for printing on the obverse side of the web 10 and a
lower printing unit section 7b for printing on the reverse
side of the web 10.
The upper printing unit section 7a comprises a
printing cylinder 8a around which a printing plate (not
shown) with an image to be transferred is wrapped, an inker
18a for supplying ink to the printing cylinder 8a, a dampener
19a for transferring water to the printing cylinder 8a,
and a blanket cylinder 9a for transferring the inked image
from the printing plate to the obverse side of the web
10. The lower printing unit section 7b likewise comprises
a printing cylinder 8b, an inker 18b, a dampener 19b, and
a blanket cylinder 9b.
The upper and lower blanket cylinders 9a and 9b
contact opposite each other at a predetermined printing
pressure. The surfaces of the blanket cylinders 9a and
9b are covered with flexible blankets (not shown), and
at the nip between these upper and lower blanket cylinders
9a and 9b, the upper and lower inked images are transferred
to both sides of the web 10.
Note that the surface of each blanket cylinder has
an axial groove formed therein, in which the longitudinally
opposite ends of the blanket are fitted. With the opposite

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ends of the blanket fitted in the axial groove, the blanket
is wrapped around the blanket cylinder surface.
Therefore, the blanket cylinder has a gap (groove)
that does not contact with the web 10. Further, the upper
and lower blanket cylinders 9a and 9b rotate in
synchronization so that the respective gaps face each other
at the nip therebetween. Therefore, when the gaps face
each other at the nip, the printing pressure between the
upper and lower blanket cylinders 9a and 9b changes and
therefore tension (tensile stress) that is applied to the
web 10 varies. As a result, the web 10 will be shifted
in the conveying direction, whereby the printing position
will also be shifted. In addition, the upper and lower
blanket cylinders 9a and 9b vibrate, so that the web 10
moves up and down at the nip exist.
To suppress such a variation in tension that is
applied to the web, in conventional offset rotary printing
machines, by disposing the upper and lower blanket
cylinders 9a and 9b so that a plane connecting the center
axes of the upper and lower blanket cylinders 9a and 9b
is inclined by a predetermined angle (hereinafter referred
to as a staggered angle) α to a plane perpendicular to
the web conveying direction, the web 10 is supported on
the areas, other than the nip, of the surfaces of the upper
and lower blanket cylinders 9a and 9b.
New developments in technology tend to reduce the
length of the above-described gap, so the required

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staggered angle a also tends to decrease. Besides, the
development of gapless blanket cylinders has made it
possible to set the staggered angle relatively freely.
In such an offset rotary printing machine, as shown
by a two-dot chain line in FIG. 15, the web 10 goes along
the surface of the upper blanket cylinder 9a for a while
on account of the adhesion of ink between the upper blanket
cylinder 9a and the web 10, and then the web 10 is separated
from the surface of the upper blanket cylinder 9a by tension
applied to the web 10. As shown in FIGS. 16A and 16B,
there are cases where the separation of the web 10 from
the upper blanket cylinder 9a causes an indeterminate
pattern (color density reduction) 16 called a delamination
pattern (hereinafter referred to simply as delamination) .
If the delamination 16 occurs on a printed surface, this
print is handled as waste paper.
To reduce the occurrence of the delamination,
Japanese Unexamined Patent Application publication No.
2005-305752 discloses a technique for reducing
delamination by setting the above-described staggered
angle to a proper angle.
SUMMARY OF THE INVENTION
The above-described delamination depends upon
printing conditions, so an optimum staggered angle to
effectively reduce delamination is considered to vary with
printing conditions.
However, the technique in the aforementioned

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Japanese Unexamined Patent Application publication No.
2005-305752 considers printing conditions collectively,
but does not vary the staggered angle according to
respective printing conditions. As a result, there are
cases where, depending on respective printing conditions,
delamination can not reduced effectively.
The present invention has been made in view of the
circumstances described above. Accordingly, it is an
object of the present invention to provide an offset rotary
printing machine and angle adjustment method that are
capable of more reliably reducing the occurrence of
delamination.
To achieve the object described above, there is
provided an offset rotary printing machine which includes
a first printing cylinder and a second printing cylinder
in which printing is performed on a web at a nip (N) between
the pair of printing cylinders, the second printing
cylinder contacting the first printing cylinder and being
shifted downstream from the first printing cylinder. The
printing machine comprises an angle adjustment mechanism
for adjusting an angle (a) of imaginary oblique plane,
which is inclined with imaginary perpendicular plane being
perpendicular to the moving direction of the web and is
connecting between each center axis of the first printing
cylinder and the second printing cylinder; and a controller
for controlling the angle adjustment mechanism, based on
parameters interrelating to a delamination occurrence

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probability () that is caused as printing is performed
by the second printing cylinder.
It is preferred that the aforementioned controller
comprises corresponding-relationship setting parts for
setting a corresponding-relationship setting part for
setting a corresponding relationship between the
delamination occurrence probability (<>) and the angle
( α ), based on printing-related information equivalent
to the parameters which includes information on images
to be printed, information on ink used, information on
property of the web, and information on a support span
of the web located downstream of the second printing
cylinder; optimum-range calculator for calculating an
optimum range for the angle (α ) which causes the
delamination occurrence probability (α ) to be a preset
probability or less, based on the corresponding
relationship that was set by the
corresponding-relationship settingpart; and command part
for outputting a command signal to the angle adjustment
mechanism to cause the angle ( α ) to be within the optimum
range calculated by the optimum-range calculator.
According to the controller described above, the
corresponding relationship between the delamination
occurrence probability and the angle is obtained based
on concrete printing-related information. As a result,
an optimum range for the angle can be calculated.
Accordingly, if the angle is set to the optimum range,

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the occurrence of delamination can be more reliably
prevented.
It is preferred that the aforementioned image
information includes a second printing area ratio (M2)
of a second image that is transferred by the second printing
cylinder, and a first printing area ratio (Ml) of a first
image that is transferred by the first printing cylinder;
the ink information includes information on ink tack (t) ;
the web-property information includes information on
rigidity (G) of the web; the support span information
includes information on an inter-color length (L*) which
is a distance between the nip (N) of the pair of printing
cylinders and a next nip of a next pair of printing cylinders
adjacent to the pair of printing cylinders; and the
corresponding-relationship settingpart sets, as an amount
interrelating to the printing-related information, a
tension variation amount (Tn) in a paper plane which
indicates a variation in tension in a width direction of
the web on a downstream side of the nip (N) of the pair
of printing cylinders, and also sets the corresponding
relationship so that the tension variation amount (Tn)
satisfies
= c • exp (Tn)
where represents the delamination occurrence
probability, c represent a constant, and Tn represents

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the tension variation amount.
Accordingly, by directing attention to the tension
variation amount, an optimum range for the angle can be
calculated. By setting the angle to the optimum range,
the occurrence of delamination can be more reliably
prevented.
It is preferred that tension variation amount (Tn)
is a function of a web separating angle ( 0 ) which is an
angle interrelating to the second printing area ratio (M2)
of the second image, the ink tack (t), and the angle (α)
and which is an angle of the web to a surface of the second
printing cylinder formed as the web is separated from the
surface; the rigidity (G) of the web; the printing area
ratio (M2) of the second image; and a contact amount (β)
of the web to a surface of the first printing cylinder
which is an amount corresponding to the angle (α ) .
It is preferred that the aforementioned controller
controls the angle adjustment mechanism under particular
conditions in which delamination can occur.
In this case, when no delamination occurs, it is
not necessary to perform wasteful operation.
It is preferred that the aforementioned particular
conditions are that the first and second images are
transferred to both sides of the web; a difference between
the first printing-area ratio and the second printing area
ratio is a preset threshold value or greater; the second
image to be transferred by the second printing cylinder

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contains a nonprinting area; and a portion of the first
image which corresponds to the nonprinting area of the
first image has a printing area ratio which is a preset
value or greater.
It is preferred that the aforementioned particular
conditions are that both an average of the first printing
area ratio of the first image and an average of the second
printing area ratio of the second image are a first reference
value or greater.
It is preferred that the aforementioned particular
conditions are that the second printing area ratio of the
second image is a second reference value or greater, and
a printing area ratio of a portion of the first image is
a third reference value or greater.
In these cases, conditions in which delamination
can occur can be decided.
It is preferred that the offset rotary printing
machine further comprises noise sensor for sensing, as
a parameter interrelating to the delamination occurrence
probability (), a noise level that is generated as
printing is performed by the pair of printing cylinders;
wherein, based on the noise level sensed by noise
sensor, the controller controls the angle adjustment
mechanism to adjust the angle ( α ) so that the noise level
is reduced.
In this case, the angle (α) is adjusted based on
the noise level which is a parameter interrelating to the

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delamination occurrence probability, whereby the
occurrence of delamination can be reliably suppressed.
It is preferred that the aforementioned controller
adjusts the angle (α ) based on the noise level at an
adjustment stage before printing is performed by the pair
of printing cylinders.
In this case, the angle (a) is adjusted before
printing is performed. Even if the angle (a) is made
constant during printing, there is no problem because
printing conditions are not changed.
In accordance with the present invention, A method
of adjusting an angle (a) of imaginary oblique plane,
which is inclined with imaginary perpendicular plane being
perpendicular to the moving direction of a web and is
connecting between each center axis of an first printing
cylinder and an second printing cylinder, the pair of
printing cylinders being equipped with an offset rotary
printing machine printing on the web at a nip (N) between
the pair of printing cylinders, the second printing
cylinder contacting the first printing cylinder and being
shifted downstream from the first printing cylinder. The
method comprises an information acquisition step of
acquiring, as parameters interrelating to a delamination
occurrence probability ( ) that is caused as printing
is performed by the second printing cylinder,
printing-related information which includes information
on images to be printed, information on ink used,

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information on property of the web, and information on
a support span of the web located downstream of the second
printing cylinder; a corresponding-relationship setting
step of setting a corresponding relationship between the
delamination occurrence probability () and the angle
( α ) , based on the information acquired by the information
acquisition step; and an angle setting step of setting
the angle (α ) to a range which causes the delamination
occurrence probability ( ) to be a preset probability
or less, based on the corresponding relationship that was
set by the corresponding-relationship setting step.
It is preferred that the aforementioned image
information includes a second printing area ratio (M2)
of a second image that is transferred by the secondprinting
cylinder, and a first printing area ratio (Ml) of a first
image that is transferred by the first printing cylinder;
the ink information includes information on ink tack (t) ;
the web-property information includes information on
rigidity (G) of the web; the support span information
includes information on an inter-color length (L*) which
is a distance between the nip (N) of the first pair of
printing cylinders and a next nip of a next pair of printing
cylinders adjacent to the first pair; and the
corresponding-relationship set ting step sets, as an amount
interrelating to the printing-related information, a
tension variation amount (Tn) in a paper plane which
indicates a variation in tension in a width direction of

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the web on a downstream side of the nip (N) of the pair
of printing cylinders, and also sets the corresponding
relationship so that the tension variation amount (Tn)
satisfies
= c • exp (Tn)
where represents the delamination occurrence
probability, c represent a constant, and Tn represents
the tension variation amount.
It is preferred that the tension variation amount
(Tn) is a function of a web separating angle (θ ) which
is an angle interrelating to the second printing area ratio
(M2) of the second image, the ink tack (t) , and the angle
( α ) and which is an angle of the web to a surface of the
second printing cylinder formed as the web is separated
from the surface; the rigidity (G) of the web; the printing
area ratio (M2) of the second image; and a contact amount
(β ) of the web to a surface of the first printing cylinder
which is an amount corresponding to the angle ( α).
It is preferred that the method further comprises
a property selection step of selecting at least either
the property of the web or the kind of ink used, based
on a corresponding relationship between at least either
the property of the web or the kind of ink used and the
delamination occurrence probability, prior to the
information acquisition step.

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In accordance with the present invention, in a
method of adjusting an angle (a) of imaginary oblique
plane, which is inclined with imaginary perpendicular
plane being perpendicular to the moving direction of a
web and is connecting between each center axis of an first
printing cylinder and an second printing cylinder, the
pair of printing cylinders being equipped with an offset
rotary printing machine printing on the web at a nip (N)
between the pair of printing cylinders, the second
printing cylinder contacting the first printing cylinder
and being shifted downstream from the first printing
cylinder. The method comprises a noise sensing step for
sensing, as a parameter interrelating to a delamination
occurrence probability ( ) that is caused as printing
is performed by the second printing cylinder, a noise level
that is generated as printing is performed by the pair
of printing cylinders; and an angle adjustment step which,
based on the noise level sensed by noise sensing step,
adjusts the angle ( a ) so that the noise level is reduced.
It is preferred that the aforementioned angle
adjustment step is carried out at an adjustment stage before
printing is performed by the pair of printing cylinders.
Therefore, according to the offset rotary printing
machine and the method of adjusting the angle of the present
invention, the angle (staggered angle) (a) is adjusted
based on parameters interrelating to the probability of
lamination occurrence, whereby the occurrence of

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delamination can be more reliably suppressed.
BRIEF DESCRIPTION OF THE DRAWINGS
The present invention will be described in further
detail with reference to the accompanying drawings
wherein:
FIG. 1 is a plan view used to explain the mechanism
of delamination occurrence, and showing an image that is
transferred from an upper blanket cylinder to a web;
FIGS. 2A to 2D are schematic diagrams used to explain
the mechanism of delamination occurrence, and showing how
the web passes between upper and lower blanket cylinders;
FIG. 3 is a schematic side view used to explain
the mechanism of delamination occurrence and an offset
rotary printingmachine of a first embodiment of the present
invention, and showing the adhesive force and tension that
are applied to the web;
FIG. 4 is a diagram used to explain the mechanism
of delamination occurrence, and showing temporal changes
in tension applied to the nonprinting area and printing
area of the web as it goes between the upper and lower
blanket cylinders;
FIG. 5 is a schematic side view used to explain
the mechanism of delamination occurrence, and showing
tension variations that occur in the web because of its
gap;
FIG. 6 is a schematic side view used to explain

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an offset rotary printing machine according to a first
embodiment of the present invention, and showing a pair
of printing cylinders;
FIG. 7 is a functional block diagram used to explain
the offset rotary printing machine according to the first
embodiment of the present invention, and showing the
functions of a controller;
FIGS. 8A to 8K are graphs used to explain the offset
rotary printing machine and according to the first
embodiment of the present invention, and showing the
corresponding relationship between printing-related
information and a variation in tension;
FIG. 9 is a graph used to explain the offset rotary
printing machine according to the first embodiment of the
present invention, and showing the corresponding
relationship between the tension variation and the
probability of delamination occurrence;
FIG. 10 is a schematic diagram used to explain the
offset rotary printing machine according to the first
embodiment of the present invention, and showing an example
of an angle adjustment mechanism;
FIGS. 11A and 11B are schematic diagrams used to
explain the offset rotary printing machine according to
the first embodiment of the present invention, and showing
different examples of the angle adjustment mechanism;
FIG. 12 is a block diagram used to explain an offset
rotary printing machine according to a second embodiment

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of the present invention, and showing a simplified
configuration of a control system;
FIG. 13 is a side view used to explain the offset
rotary printing machine according to the first embodiment
of the present invention, and showing a simplified
configuration of the offset rotary printing machine;
FIG. 14 is a schematic diagram used, to explain the
offset rotary printing machine according to the first
embodiment of the present invention, and showing the
configuration of the printing unit;
FIG. 15 is a schematic side view used to explain
a conventional offset rotary printing machine, and showing
a pair of printing cylinders;
FIG. 16A illustrates an example of delamination
caused by printing, an image transferred to a web of paper
being shown;
FIG. 16B illustrates another example of
delamination causedby printing, another image transferred
to the web being shown;
FIGS. 17A and 17B are diagrams used to explain the
mechanism of delamination occurrence, and schematically
showing tension wrinkles caused by a variation in tension;
and
FIGS. 18A to 18D are graphs used to explain the
offset rotary printing machine and angle adjustment method
according to the first embodiment of the present invention,
and showing the corresponding relationship between

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printing-related information and the tension variation.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
(Mechanism of Delamination Occurrence)
Before describing embodiments of the present
invention, a description will be given of the mechanism
of delamination occurrence that the present inventors have
understood. Note that the same parts as those employed
in the description of the related art will be described,
using the same reference numerals.
First, a description will be given of the mechanism
of delamination occurrence in the case where an image on
the obverse side of a web of paper (which is transferred
by an upper blanket cylinder) includes a nonprinting area
or an area with a low printing area ratio equivalent to
the nonprinting area.
FIG. 1 shows an obverse-side image that is
transferred from an upper blanket cylinder 9a to the obverse
side of a web of paper 10, and FIGS. 2A to 2D are schematic
diagrams showing how the web 10 passes between upper and
lower blanket cylinders 9a and 9b. In this embodiment,
the upper blanket cylinder (second printing cylinder) 9a
is arranged downstream, while the lower blanket cylinder
(first printing cylinder) 9b is arranged upstream. The
configuration of the blanket cylinders 9a and 9b is not
limited to this example.
As shown in FIG. 1, the obverse-side image includes

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a nonprinting area (or an area with a low printing area
ratio) W. Although not shown, a reverse-side image that
is transferred from the lower blanket cylinder 9b to the
reverse side of the web 10 has a printing area ratio equal
to or greater than a predetermined threshold value over
its entire surface that includes an area corresponding
to the nonprinting area of the obverse-side image.
As shown in FIG. 2A, the upper and lower blanket
cylinders 9a and 9b contact in opposition to each other
at a predeterminedprinting pressure, and at the nip between
these blanket cylinders 9a and 9b, the inked images are
transferred to both sides of the web 10. The upper and
lowerblanket cylinders 9a and 9bare disposedat a staggered
angle α so that the upper blanket cylinder 9a is positioned
downstream with respect to the web moving direction and
the lower blanket cylinder 9b is positioned upstream.
A description will hereinafter be given of how the
web 10 and upper and lower blanket cylinders 9a and 9b
operate as the web 10 to which the obverse-side image shown
in FIG. 1 is transferred passes through the nip.
First, as in interval X1 to X2 of FIG. 1, in the
case where both sides of the web 10 are printed at high
printing area ratios greater than a predetermined level,
as shown in FIG. 2A, after passing through the nip N, the
web 10 is separated from the lower blanket cylinder 9b
and brought into contact with the upper blanket cylinder
9a.

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This is considered to be for the following reasons.
Since the upper blanket cylinder 9a is shifted downstream
with respect to the web moving direction than the lower
blanket cylinder 9b, the upper blanket cylinder 9a becomes
closer to the orbit of the web 10 after the web 10 passes
through the nip N. As a result, the web 10 is brought
into contact with the upper blanket cylinder 9a by the
adhesive force of the inked image of the upper blanket
cylinder 9a. Therefore, conversely, when the setting of
the staggered angle a is changed so that the lower blanket
cylinder 9b is shifted downstream of the upper blanket
cylinder 9a, the web 10 is first separated from the upper
blanket cylinder 9a.
After the web 10 has been separated from the lower
blanket cylinder 9b, because of the adhesive force (which
is applied in the radial direction of the upper blanket
cylinder 9a) between the upper blanket cylinder 9a and
the web 10 resulting from the inked image of the upper
blanket cylinder 9a, the web 10 goes along the surface
of the upper blanket cylinder 9a to a separating position
A without being separated from the upper blanket cylinder
9a and is separated from the upper blanket cylinder 9a
at the separating position A. Note that the angle of
rotation of the upper blanket cylinder 9a from the nip
N to the separating position A will hereinafter be referred
to as a contact angle y .
When the nonprinting area W indicated by the

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interval X2 to X3 of FIG. 1 passes through the nip N, as
shown by a solid line in FIG. 2B, the adhesive force of
ink to be transferred from the upper blanket cylinder 9a
is small at that portion in the width direction of the
web 10 which corresponds to the nonprinting area W, and
consequently, the web 10 is not separated from the lower
blanket cylinder 9b by the adhesive force of ink that is
transferred from the lower blanket cylinder 9b. Thus,
conversely, the web 10 is first separated from the upper
blanket cylinder 9a.
On the other hand, the printing areas on the opposite
sides in the width direction of the nonprinting area W,
as shown by a dashed line in FIG. 2B, are first separated
from the lower blanket cylinder 9b in the same manner shown
in FIG. 2A and then separated from the upperblanket cylinder
9a at the separating position A.
Thereafter, if the web 10 further goes forward,
as shown in FIG. 2C, the nonprinting area W begins to
separate from the lower blanket cylinder 9b. On the other
hand, the printing areas on the opposite sides in the width
direction of the nonprinting area W separate from the upper
blanket cylinder 9a at the separating position A, as in
the case of FIG. 2C.
When the nonprinting area iVis completely separated
from the lower blanket cylinder 9b, as shown in FIG. 2D,
in the interval X2 to X3 of FIG. 1 the web 10 has already
been separated from upper blanket cylinder 9a and therefore

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the separating position between the web 10 and the upper
blanket cylinder 9a moves from the separating position
A to another separating position B. Note that the
separating position A of the printing area does not change.
Thus, when the obverse-side image contains the
nonprinting area W and the portion of the reverse side
image which corresponds to the nonprinting area W has a
printing area ratio greater than a predetermined level,
the separating position of the web 10 from the upper blanket
cylinder 9a which corresponds to the nonprinting area W
moves from position A to position B.
FIG. 3 shows the tension applied to the web 10 in
the moving direction at the separating position A of FIG.
2A and separating position B of FIG. 2D, and the adhesive
force applied to the web 10 by the upper blanket cylinder
9a.
As shown in FIG. 3, at the separating position A,
adhesive force F1 is applied to the web 10 in the radial
direction of the upper blanket cylinder 9a by the inked
image of the upper blanket cylinder 9a.
Because the web 10 is separated from the upper
blanket cylinder 9a at the separating position A, a
separating force which is the same in magnitude as the
adhesive force Fl is applied to the web 10 in the opposite
direction at the separating position A, as shown by a dashed
line in FIG. 3. This separating force is createdby tension
T1 applied to the web 10. More specifically, if the

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separating direction of the web 10 with respect to the
tangential direction of the upper blanket cylinder 9a at
the separating position A is represented by an angle 9
1, then the separating force at the separating position
A can be expressed as T1 • sin θ 1.
At the separating position B, adhesive force F2
is applied to the web 10 in the radial direction of the
upper blanket cylinder 9a. Since the web 10 is separated
from the upper blanket cylinder 9a at the separating
position B, a separating force which is the same in magnitude
as the adhesive force F2 is applied to the web 10 in the
opposite direction at the separating position B, as shown
by a dashed line in FIG. 3. This separating force can
be expressed as T2 • sin θ 2, using the separating angle
9 2 of the web 10 at the separating position B and tension
T2 applied to the web 10.
Now, consider the adhesive force F1 applied at the
separating position A and the adhesive force F2 applied
at the separating position B. The adhesive forces Fl and
F2 result mainly from the viscosity of ink, so they are
determined by an ink tack value t and a printing area ratio
(i.e., an ink amount) of an obverse-side image that is
printed. That is, if the kind of ink to be used is selected,
when the printing area ratios at positions A and B are
the same, or a difference between them is considered
practically negligible, the magnitudes of the adhesive
forces Fl and F2 can be the to be approximately the same.

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If the adhesive forces F1 and F2 are approximately
the same in magnitude, then the separating positions A
and B and separating angles θ 1 and θ 2 are determined by
the magnitudes of tension Tl and tension T2.
For example, if the tension applied to the web 10
becomes smaller, the separating angle becomes larger (or
becomes close to 90° ) . On the other hand, the tension
applied to the web 10 becomes larger, the separating angle
becomes smaller (or becomes close to 0° ) .
A variation in the tension applied to the web 10
is also caused by a variation in the separating position
(i.e., a variation in the contact angle y ) . As described
with reference to FIGS. 2A to 2D, in the case where the
separating position of the web 10 moves, for example, from
the position A to the position B, the tension applied to
the web 10 varies with the movement of the separating
position.
FIG. 4 shows temporal changes in the tension applied
to the web 10 shown in FIGS. 2A to 2D. Note in FIG. 4
that tension Tw applied to the nonprinting area W is
indicated by a solid line, while tension Tc applied to
the printing areas on both sides in the width direction
of the nonprinting area W is indicated by a dashed line.
As shown in FIG. 4, in the state of FIG. 2A (interval
0 to tl in FIG. 4), tension applied to the nonprinting
area of the web 10 is approximately the same as that applied
to the printing area of the web 10.

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In the states of FIGS. 2B and 2C (interval t1 to
t2 in FIG. 4) , the nonprinting area W adheres to the lower
blanket cylinder 9b, and the printing area positioned
upstream of the nonprinting area W adheres to the upper
blanket cylinder 9a until the separating position A, so
the tension applied to the nonprinting area W increases
gradually.
Next, in the state of FIG. 2D (interval t2 to t3
in FIG. 4) , the nonprinting area W is completely separated
from the lower blanket cylinder 9b at the separating
position A, so the tension Tw applied to the web 10 is
suddenly reduced in a moment. At this stage, the
separating position of the web 10 is moved from position
A to position B.
When the observe-side printing area following after
the nonprinting area W reaches the separating position
B, the adhesive force F2 between the web 10 and the upper
blanket cylinder 9a is suddenly applied and therefore the
tension Tw applied to the web 10 increases suddenly.
Thereafter (interval after t3), the separating
position of the web 10 returns to the position A and becomes
stable, so that the tension Tw applied to the nonprinting
area W becomes approximately equal to the tension Tc.
Thus, a sudden change in the tension Tw applied
to the web 10 causes a difference between the tension Tw
of the nonprinting area W and the tension Tc of the printing
area, so that the tension applied to the web 10 varies

- 25 -
in the width direction of the web 10. This variation will
hereinafter be referred to as tension variation Tn.
If the tension variation Tn occurs, wrinkles will
occur at the boundary WS (see FIG. 1) in the web moving
direction between the nonprinting area W and the printing
area. These wrinkles will hereinafter be referred to as
separation wrinkles or tension wrinkles. The separation
wrinkles are considered to cause a variable density
boundary (i.e., delamination) to occur in a printed image.
Now, a description will be given of the mechanism
of delamination occurrence in the case where obverse-side
and reverse-side images with a uniform high printing area
ratio (e.g., 80%) are transferred to both sides of the
web 10.
Although described in detail later, even in the
case where images with a high printing area ratio are
respectively transferred to both sides of the web 10, as
with the above case where the obverse-side image contains
a nonprinting area, a variation in the tension applied
to the web 10 likewise causes the occurrence of
delamination.
However, the case where images with a high printing
area ratio are transferred to both sides of the web 10
differs from the above case in that the main cause of the
tension variation is not a variation in the separating
position but the gap formed in the circumference of the
upper blanket cylinder 9a.

- 26 -
As shown in FIG. 5, in the case where a gap G is
formed in the circumference of the upper blanket cylinder
9a, the inked image is not transferred to the web 10 at
the gap G and therefore there is no adhesive force between
the web 10 and the upper blanket cylinder 9a in the vicinity
of the gap G.
Since the printing area ratios of the obverse-side
and reverse-side images are the same, the web 10 appears
to have no tension variation at one view, but tension
wrinkles have occurred due to the balance of rigidity and
expansion/contraction of the web 10.
The tension wrinkles can occur at arbitrary
positions in the width direction (perpendicular to the
web moving direction) of the web 10.
The cause of the occurrence of the tension wrinkles
is as follows. When the gap in the circumference of the
upper blanket cylinder 9a is passing the web separating
position, no adhesive force is applied to the web 10 at
the gap, and after passing the gap, an adhesive force is
again applied to the web 10.
Because of this, the tension applied to the web
10 varies in the width direction of the web 10, and the
contact angles y (i.e., web separating positions) of the
web 10 with respect to the upper blanket cylinder 9a become
non-uniform, as shown by a dashed line in FIG. 17A. As
shown in FIG. 17B, tension (see arrows) varies greatly
with the web separating positions, so that tension wrinkles

-21 -
are created. Note that the total tension in the width
direction of the web 10 does not change.
That is, the separating position and direction of
the web 10 from the upper blanket cylinder 9a is determined
by the balance of the adhesive force of the web and the
tension applied to the web. Since the balances differ
from one another in the web width direction, the web
separating positions and angles differ from one another,
as shown in FIG. 17A. Such a variation (difference) in
the tension balance in the web width direction causes the
propagation of tension balance, whereby tension wrinkles
are created. This can cause delamination that is widen
toward the end, or delamination that occurs on the way.
(Summary of the Mechanism of Delamination Occurrence)
While the mechanism of delamination occurrence has
been described in two cases, in either case a sudden
variation in the tension applied to the web 10 increases
the tension variation Tn, thereby resulting in the
occurrence of delamination. Therefore, the greater the
tension variation Tn of the web, the greater the
delamination occurrence probability .
For conditions concerning the tension variation
Tn, the inventors have found the following facts:
(1) The larger the staggered angle, the larger the
contact angle y .
(2) The larger the contact angle y , the greater the
tension variation Tn.

- 28 -
(3) The greater the paper rigidity G, the smaller the
tension variation Tn. Note that the paper rigidity G is
a value representing the difficulty of deforming paper.
(4) Adhesive force F is proportional to tension Tn.
(5) The larger the paper elongation amount L, the greater
the tension variation Tn. More particularly, in the case
where the paper elongation amount L is large, the rigidity
in the width direction of the web 10 becomes small and
therefore the tension variation Tn in the web width
direction becomes great.
(6) The shorter the inter-color length, the smaller the
tension variation Tn. To reduce the delamination
occurrence probability , it is necessary to make the
tension variation Tn as small as possible.
To reduce the tension variation Tn, it is considered
necessary to set the staggered angle a properly. If the
staggered angle a is made smaller, the contact angle y
becomes smaller (i.e., the paper separating position is
moved downward). This reduces the tension variation Tn
and effectively reduces delamination.
However, since the tension variation Tn depends
upon adhesive force F, paper rigidity G, paper elongation
amount L, etc., a reduction in the staggered angle a alone
cannot reduce the tension variation Tn effectively.
For instance, in the case where the staggered angle
a is made 0 degrees (vertical), the behavior of the web
10 becomes unstable as it is separated from the upper and

- 29 -
lower blanket cylinders 9a and 9b. As a result, at the
nip between the upper and lower blanket cylinders 9a and
9b, the image transferring position is shifted and
therefore double transferring of an image is performed.
Thus, there is a strong possibility that printing faults
other than delamination will occur.
Also, in the case where an image to be transferred
from the upper blanket cylinder 9a is an extremely small
image (or an image whose printing area ratio is small)
while an image to be transferred from the lower blanket
cylinder 9b is an extremely large image (or an image whose
printing area ratio is high), the adhesive force between
the obverse side of the web 10 and the upper blanket cylinder
9a differs from the adhesive force between the reverse
side of the web 10 and the lower blanket cylinder 9b, and
consequently, a proper staggered angle α varies.
Furthermore, changing the contact amount β (see
FIG. 15) by the setting of the staggered angle α has a
great influence on the probability of delamination
occurrence.
More specifically, the tension variation Tn varies
evenby the kindof inkused, paper kindof web 10, respective
printing area ratios of inked images to be transferred
from the upper and lower blanket cylinders 9a and 9b (which
correspond to the amounts of ink to be transferred),
positions of images disposed, and contact amount β , so
it is necessary to set a proper staggered angle α , taking

- 30 -
these conditions into account.
[First Embodiment]
An embodiment of the present invention will
hereinafter be described with reference to the drawings.
The drawings used in the description of the related art
are also employed in described the present invention.
FIGS. 6, 7, 8A to 8K, 9, 10, 11A and 11B are used
for explaining an offset rotary printing machine of a first
embodiment of the present invention. FIG. 6 is a schematic
side view showing a pair of printing cylinders, FIG. 7
is a functional block diagram showing the functions of
a controller, and FIGS. 8A to 8K each illustrate the
corresponding relationship between printing-related
information and a variation in tension. FIG. 9 is a graph
showing the corresponding relationship between the tension
variation and the probability of delamination occurrence,
FIG. 10 a schematic diagram showing an example of an angle
adjustment mechanism, and FIGS. 11A and 11B schematic
diagrams showing different examples of the angle
adjustment mechanism. In the present embodiment, the
present invention is applied to the same printing machine
as that employed in the description of the related art.
As shown in FIG. 13, the offset rotary printing
machine of the present invention includes a web feeder
section 1, an in-feed device 2, a printing section 3, a
dryer section 51, a cooling section 52, a web pass section
53, and a folding machine 6. A roll of web (continuous

- 31 -
paper) 10 attached to the web feeder section 1 is supplied
by the in-feed device 2 and is printed in the printing
section 3.
Theprintingsection 3 comprises fourprintingunits
7 that respectively correspond to ink colors of C (cyan) ,
M (magenta) , Y (yellow), and K (black) . It is noted that
the number of printing units 7 may be one. The printing
units 7 are installed according to the number of colors
that are printed.
The web 10 printed in the printing section 3 goes
through the dryer section 51, cooling section 52, and web
pass section 53 and is conveyed to the folding machine
6, in which the folded web 10 is made.
(Configuration of the Printing Unit)
As shown in FIG. 14, the printing unit 7 comprises
an upper printing unit 7a for printing on the obverse side
of the web 10 and a lower printing unit 7b for printing
on the reverse side of the web 10.
The upper printing unit 7a comprises a printing
cylinder 8a around which a printing plate (not shown) with
an image to be printed is wrapped, an inker 18a for supplying
ink to the printing cylinder 8a, a dampener 19a for
transferring water to the printing cylinder 8a, and a
blanket cylinder 9a for transferring the inked image from
the printing plate to the obverse side of the web 10. The
lower printing unit 7b similarly comprises a printing
cylinder 8b, an inker 18b, a dampener 19b, and a blanket

- 32 -
cylinder 9b.
As shown in FIG. 6, in each of the printing units
7, the downstream blanket cylinder (second printing
cylinder) 9a and upstreamblanket cylinder (first printing
cylinder) 9b contact in opposition to each other at a
predetermined printing pressure. In other words, second
printing cylinder 9a is in contact to the first printing
cylinder 9b and is shifted downstream from first printing
cylinder 9b. At the nip between these blanket cylinders
9a and 9b, inked images are transferred to both sides of
the web 10, respectively.
In the present embodiment, the downstream blanket
cylinder 9a, arranged above the web 10 for transferring
the inked image to the obverse side of the web 10, is called
an upper blanket cylinder, while the upstream blanket
cylinder 9b, arranged under the web 10 for transferring
the inked image to the obverse side of the web 10, is called
a lower blanket cylinder. The configuration of the blanket
cylinders 9a and 9b is not limited to this example.
Note that the surface of each of the blanket
cylinders 9a and 9b has an axial groove formed therein,
in which the longitudinally opposite ends of the blanket
are fitted. With the opposite ends of the blanket fitted
in the axial groove, the blanket is wrapped around the
blanket cylinder surface.
Therefore, the blanket cylinder has a gap (groove)
that does contact with the web 10. Further, the upper

- 33 -
and lower blanket cylinders 9a and 9b rotate in
synchronization so that the respective gaps face each other
at the nip therebetween.
The upper and lower blanket cylinders 9a and 9b
are further disposed so that an imaginary oblique plane
connecting the center axes of the upper and lower blanket
cylinders 9a and 9b is inclined by a predetermined angle
(hereinafter referred to as a staggered angle) a to an
imaginary perpendicular plane to the web conveying
direction. Stated another way, the upper blanket cylinder
9a is shifted downstream in the rotation direction of the
lower blanket cylinder 9b (downstream in the web conveying
direction) from the position right above the lower blanket
cylinder 9b by the staggered angle α , or the lower blanket
cylinder 9b is shifted upstream in the rotation direction
of the upper blanket cylinder 9a (downstream in the web
conveying direction) from the position right under the
upper blanket cylinder 9a by the staggered angle α .
The staggered angle a canbe adjustedby an actuator
20, which is in turn controlled by a controller 30. The
detailed configuration of the actuator 20 will be described
later.
(Functional Construction of the Controller)
The functional construction of the controller 30
will be described with reference to FIG. 7. As shown in
the figure, the controller 30 is constructed by a computer
from a storage device 31, a calculator

- 34 -
(corresponding-relationship setting means and
optimum-range calculator) 32, and a command device 33.
The storage device 31 stores printing-related
information of various kinds (which are to be described
later) as parameter information interrelated with the
probability of delamination occurrence which is caused
by the transfer of the inked image from the upper blanket
cylinder 9a.
The calculator 32 sets the corresponding
relationship between the probability of delamination
occurrence and the above-described staggered angle on the
basis of printing-related information, and calculates an
optimum range for the staggered angle that causes the
probability of delamination occurrence to be a
predetermined probability or less, on the basis of the
corresponding relationship. The command device 34
transmits a drive signal for driving the actuator 20 so
that the staggered angle a becomes equal to an angle of
inclination calculated by the calculator 33.
(Printing-Related Information)
The storage device 31 stores image information,
ink information, and material information web property
information and supports span information of the web 10,
as printing-related information.
These pieces of printing-related information
may be input to the storage device 31 beforehand
(information acquisition step) . Prior to this, at least

- 35 -
either the web property of the web or the kind of ink to
be used is selected beforehand on the basis of the
corresponding relationship with the probability of
delamination occurrence that will be described later
(property selection step).
As image information, the printing area ratio data
Mt of an obverse-side image (printing area ratio M2 of
a second image) that is transferred from the upper blanket
cylinder 9a to the obverse side of the web 10, and the
printing area ratio data Mb of a reverse-side image
(printing area ratio Ml of a first image) that is transferred
from the upper blanket cylinder 9a to the reverse side
of the web 10, are input and stored.
As ink information, ink tack information t is input
and stored for ink of each color that is used. The ink
tack information t represents a value relating to the
adhesive force (viscosity) of ink.
As the property information of the web 10,
information of rigidity G and paper elongation amount L
of the web 10 is stored. The paper elongation amount L
is related to the rigidity G and is the amount of deformation
of the web 10 by the tension applied to the web 10, but
the paper elongation amount L can be calculated according
to the paper quality (paper kind) of the web 10 and the
tension applied to the web 10. Therefore, the paper
elongation amount L that corresponds to paper kind and
tension can be calculated beforehand by experiment, etc.

- 36 -
As support span information, the information of
the distance (inter-color length) L* of the two nips between
two printing units 7 is stored. The storage device 31
also stores the current staggered angle a .
The storage device 31 further stores the contact
amount β as related information of the support span
information.
As shown in FIG. 6, the contact amount β is expressed
as the length that the web 10 contacts the lower blanket
cylinder 9b until the nip between the upper and lower blanket
cylinders 9a and 9b, but it may be expressed as the angle
of rotation of the lower blanket cylinder 9b.
Note that the contact amount β can be calculated
from the relationship between the horizontal travel
position of the web 10 (travel position of the web 10 in
the state before the web 10 contacts the lower blanket
cylinder 9b) and the staggered angle a .
The storage device 31 further stores the information
of the contact angle y . The contact angle y can be
calculated according to the paper quality of the web 10,
the kind of ink, and the printing area ratio of an image
beforehand by experiment, etc.
The storage device 31 further stores the surface
roughness A of the upper blanket cylinder 9a as
printing-related information.
The storage device 31 further stores maps
(functions), shown in FIGS. 8A to 8K, which each represent

- 37 -
the corresponding relationship between each information
described above and an amount interrelating to the
information. Particularly, employing these maps, the
tension variation Tn is set as an amount interrelating
to the printing-related information of various kinds
described above.
Note that these map data are calculated beforehand
by experiment on the basis of the mechanism of delamination
occurrence described above.
Now, these map data will be described. FIG. 8A
illustrates the corresponding relationship between the
contact angle y and the tension variation Tn. If the
contact angle y increases, the tension variation Tn also
increases nearly linearly. Thatis, the tension variation
Tn corresponding to the contact angle y is expressed as
the following Eq. (1):
Tn = a1f1 ( γ ) (a1 is a constant) - - - - (1)
FIG. 8B illustrates the corresponding relationship
between the rigidity G of the web 10 and the tension
variation Tn. If the rigidity G increases, the tension
variation Tn decreases. It is in inverse proportion to
the rigidity G. That is, the tension variation Tn
corresponding to the rigidity G is expressed as the
following Eq. (2):

- 38 -
Tn = a2f2(1/G) (a2 is a constant) ----(2)
FIG. 8C illustrates the corresponding relationship
between the staggered angle α and the separating angle
θ . If the staggered angle α increases, the separating
angle θ also increases nearly linearly. That is, the
separating angle 9 corresponding to the staggered angle
a is expressed as the following Eq. (3):
θ = a3f3 ( α ) (a3 is a constant) ---- (3)
FIG. 8D illustrates the corresponding relationship
between F • θ (where F is the adhesive force between the
upper blanket cylinder 9a and the web 10 and 9 is the
separating angle) and the tension variation Tn. If the
value F • θ increases, the tension variation Tn also
increases. That is, when the ink tack t and the paper
quality (paper kind) of the web 10 remains the same, the
adhesive force F and the separating angle 9 (which is an
amount relating to the adhesive force F) can be handled
as a pair of parameters. The tension variation Tn
corresponding to F • θ is expressed as the following Eq.
(4):
Tn = a4f4(F • θ ) (a4 is a constant) ----(4)
FIG. 8E illustrates the corresponding relationship

- 39 -
between the paper elongation amount L of the web 10 and
the tension variation Tn. If the paper elongation amount
L increases, the tension variation Tn also increases. That
is, the tension variation Tn corresponding to the paper
elongation amount L is expressed as the following Eq. (5) :
Tn = a5f5 (L) (a5 is a constant) ---- (5)
FIG. 8F illustrates the corresponding relationship
between the inter-color length L* and the tension variation
Tn. If the inter-color length L* increases, the tension
variation Tn also increases nearly linearly. That is,
the tension variation Tn corresponding to the inter-color
length L* is expressed as the following Eq. (6):
Tn = a6f6(L*) (a6 is a constant) ----(6)
FIG. 8G illustrates the corresponding relationship
between the contact amount β and the tension variation
Tn. The tension variation Tn has a predetermined minimum
value, and if the contact amount β increases or decreases
from the minimum value, the tension variation Tn increases.
The tension variation Tn corresponding to the contact
amount β is expressed as the following Eq. (7):
Tn = a7f7(β) (a7 is a constant) ----(7)

- 40 -
FIG. 8H illustrates the corresponding relationship
between the adhesive force F between the upper blanket
cylinder 9a and the web 10 and the printing area ratio
Mt of the obverse side of the web 10. If the value Mt
increases, the adhesive force F also increases nearly
linearly. That is, the adhesive force F corresponding
to the printing area ratio Mt is expressed as the following
Eq. (8):
F = a8f8 (Mt) (a8 is a constant) ----(8)
FIG. 8I illustrates the corresponding relationship
between the surface roughness A of the upper blanket
cylinder 9a and the adhesive force F. If the surface
roughness A increases (i.e., if the surface of the upper
blanket cylinder 9a becomes rougher), the adhesive force
F decreases in approximately inverse proportion. That
is, the adhesive force Fcorresponding to surface roughness
A of the upper blanket cylinder 9a is expressed as the
following Eq. (9):
F = a9f9 (A) (a9 is a constant) ---- (9)
FIG. 8 J illustrates the corresponding relationship
between the staggered angle a and the adhesive force F.
If the staggered angle α increases, the adhesive force
F decreases in approximately inverse proportion. That

- 41 -
is, the adhesive force F corresponding to the staggered
angle a is expressed as the following Eq. (10):
F = a10f10(α) (a10 is a constant) ----(10)
FIG. 8K illustrates the corresponding relationship
between the ink tack t and the tension variation Tn. If
the ink tack t increases, the tension variation Tn also
increases. That is, the tension variation Tn
corresponding to the ink tack t isexpressedas the following
Eq. (11):
Tn = a11f11(t) (a11 is a constant) ----(11)
The calculator 32 calculates the tension variation
Tn that occurs in the web 10, by taking parameters into
consideration, using the printing-related information and
map data prescribing the corresponding relationships that
are stored in the storage device 31.
The storage device 31, as shown in FIG. 9, stores
a function of the delamination occurrence probability
and tension variation Tn (exponential function expressed
in Eq. 12) as map data, and the calculator 32 sets the
corresponding relationship between the delamination
occurrence probability and the staggered angle α so
that the tension variation Tn, calculated as described
later as an amount interrelated to the printing-related

- 42 -
information, meets the following Eq. (12):
= c • exp(Tn) (where c is a constant) ----(12)
Based on this corresponding relationship, the
calculator 32 calculates an optimum range for the staggered
angle α which causes the lamination occurrence
probability to be a predetermined probability D or
less.
The tension variation Tn is a function of the contact
angle y , rigidity G of web 10, separating angle θ , F •
θ (production of adhesive force F and separating angle
θ ) , paper elongation amount L of web 10, inter-color length
L*, contact amount β , and ink tack t, and can be expressed
as:
Tn a y , G, θ , F • θ , L, L*, β , t
The adhesive force F is a function of the printing
area ratio Mt of the obverse side of web 10, surface
roughness A of the upper blanket cylinder 9a, and staggered
angle α, and can be expressed as:
F oc Mt, A, α
The tension variation Tn can be calculated by giving
a suitable weight to each function and adding all functions,

- 43 -
using the functions (1) to (11) shown in the map data of
FIG. 8.
That is, the tension variation Tn, for example,
can be expressed as the following Eq. (13):
Tn = k1 γ + k2G + k3 θ + k4F • θ + k5L + k6L* +
k7 β + k8t --- (13)
where k1 to k8 are coefficients for weighting each parameter
and are suitably set by experiment, etc. Since the
parameters are interrelated with one another, the
coefficient of a parameter representative of a plurality
of parameters may be set to a large value, while the
coefficient of the remaining parameters may be set to a
small value (or zero).
For instance, the printing area ratio Mt of the
obverse-side image, paper quality of the web 10 (rigidity
G, paper elongation amount L, and if necessary, paper
surface roughness), ink tack t, and surface roughness A
of the upper blanket cylinder 9a, as printing information,
are fixed without being changed at the time of printing.
Therefore, as shown in FIGS. 18B to 18D and FIGS. 8H and
8I, employing the maps indicating the corresponding
relationship between each of these parameters and the
adhesive force, the adhesive forces F corresponding to
the parameters Mt, G, L, t, and A input in the storage
device 31 are derived, and based on the corresponding

- 44 -
relationship between the adhesive force F and the
separating angle θ such as the one shown in FIG. 18A, the
separating angle θ of the web 10 is assumed.
Note that the separating angle θ is determined by
the adhesive force F and total tension T applied in the
full width direction of the web 10. The total tension
T may be input to the storage device 31 beforehand.
The total tension T may be obtained by installing
between the printing units 7 a non-contact type tension
sensor such as an acoustic tension sensor, and measuring
the total tension of the web 10 between the printing units
7. Alternatively, by measuring tension in the vicinities
of the web feeder section 1 and cooling section 52, and
calculating the weighted average of the tension near the
web feeder section 1 and tension near the cooling section
52, the total tension between the printing units 7 may
be set. As a simpler method, either the tension of the
web 10 measured near the web feeder section 1 or the tension
of the web 10 measured near the cooling section 52 may
be employed as the total tension T.
Using themap shown in FIG. 8A, the tension variation
Tn is calculated from the separating angle 9 assumed; the
delamination occurrence probability is calculated using
the map data shown in FIG. 9; and an optimum range for
the staggered angle α is derived.
The blanket cylinders, kind of ink to be used, and
inter-color length L* are normally not changed over a long

- 45 -
period of time without being interchanged each time
printing is performed. Therefore, the adhesive force F
may be calculated from the printing area ratio Mi of the
obverse-side image and paper quality (rigidity G) of the
web 10, based on the assumption that the same surface
roughness A of the upper blanket cylinder 9a, ink tack
t, and inter-color length L* are always employed.
The corresponding relationships between the
parameters and the adhesive force F may be obtained
beforehand by experiment, etc. In this case, if the
obtained corresponding relationships are stored as a
database, a corresponding adhesive force F can be output
when the value of each parameter is input.
When the current staggered angle α stored in the
storage device 31 is departed from the above-described
optimum range, the command device 33 functions to transmit
a command signal to the actuator 20 so that the staggered
angle α is within the optimum range.
Note that the command device 33 is configured to
transmit the above command signal only when particular
conditions for the occurrence of delamination are
satisfied. Therefore, when the particular conditions are
not satisfied, as in the range indicated by an arrow in
FIG. 9, the delamination occurrence probability is zero
or near zero.
The particular conditions are that
(1) Images are transferred to both sides of the web 10,

- 46 -
(2) A difference in printing-area ratio between the
printing area ratio data Mt of the obverse side and the
printing area ratio data Mb of the reverse side is larger
than a preset threshold value,
(3) An obverse-side image contains a nonprinting area;
and
(4) That portion of a reverse-side image which
corresponds to the nonprinting area of the obverse-side
image has a printing area ratio which is a preset value
or greater.
When the conditions (1) to (4) are all satisfied,
the above particular conditions are satisfied.
In addition to the above (1) to (4), the particular
conditions may further include that
(5) both an average of the printing area ratio data Mt
of an obverse-side image and an average of the printing
area ratio data Mt of a reverse-side image are a first
reference value o,r greater. When the conditions (1) to
(5) are all satisfied, the above particular conditions
may be satisfied. Alternatively, if the condition (5)
is satisfied, the particular conditions may be satisfied,
whether the conditions (1) to (4) are satisfied or not.
The above particular conditions may further include
that (6) the printing area ratio Mt of an obverse-side
image is a second reference value or greater, and (7) the
printing area ratio Mb of a reverse-side image is a third
reference value or greater. Alternatively, if the

- 47 -
conditions (6) and (7) are satisfied, the particular
conditions may be satisfied regardless of whether the other
conditions have been satisfied.
(Angle Adjustment Mechanism)
Now, embodiments of the actuator 20 as an angle
adjustment mechanism will be described. Although various
constructions are considered as embodiments of the
actuator 20, some of them will be described.
Referring to FIG. 10, there is shown an embodiment
of the actuator 20. Note in the figure that the dimensions
of the upper and lower plate cylinders 8a and 8b, blanket
cylinders 9a and 9b, and staggered angle a are larger than
the actual dimensions of them.
As shown in FIG. 10, the lower portion of the printing
unit 7 is provided with a pivot 40 that allows the printing
unit 7 to rotate pivotally. The printing unit 7 is pivoted
on the pivot 40 by a drive mechanism not shown. This makes
it possible to adjust the staggered angle α, as shown by
a two-dot chain line.
The drive mechanism can employ a combination of
screws and motors, or an air cylinder. It may be any type
of drive mechanism if it is able to properly adjust the
staggered angle α in response to a command signal from
the command device 33 of the controller 30.
Referring to FIG. 11, there are shown other
embodiments of the actuator 20.
As shown in FIGS. 11A and 11B, the staggered angle

- 48 -
a is adjusted by pivotally rotating plate cylinders 8a
and 8b and blanket cylinders 9a and 9b with a drive mechanism
not shown, using arms 41 to 43.
In the example shown in FIG. 11A, the lower blanket
cylinder 9b is pivotally rotated by the arm 41 attached
to or near the center of the upper blanket cylinder 9a,
and the lower plate cylinder 8b is pivotally rotated by
the arm 42 so it follows the pivotal movement of the lower
blanket cylinder 9b.
In the example shown in FIG. 11B, the lower blanket
cylinder 9b and lower plate cylinder 8b are pivotally
rotated as one body by the arm 43.
With the constructions described above, it is
possible to set a proper staged angle α in response to
a command signal from the command device 33.
(Effects)
Since the offset rotary printing machine and angle
adjustment method according to the first embodiment of
the present invention are constructed as described above,
an optimum range for the staggered angle α can be
calculatedby directing attention to the tension variation
Tn which interrelates with parameters associated with
printing-related information which vary each time printing
is performed, such as the printing area ratio data Mt and
Mb of obverse-side and reverse-side images which vary with
the image kind used, ink tack t which varies with the kind
of each color used (ink tack t which varies according to

- 49 -
ink manufactures) , rigidity G which varies with the kind
of web 10 used, etc. By adjusting the staggered angle
a according to the calculated optimum range so that the
delamination occurrence probability is a predetermined
probability or less, the first embodiment of the present
invention is capable of reliably preventing the occurrence
of delamination.
In addition, the staggered angle α is adjusted only
when the particular conditions in which delamination can
occur are satisfied. Therefore, for example, as in the
case where only one side of the web 10 is printed, when
no delamination occurs, the staggered angle a is not
adjusted. Accordingly, wasteful control can be reduced.
Besides, by previously selecting the material of
the web 10 and kind of ink that are advantageous in
suppressing delamination, the occurrence of delamination
can be more reliably prevented.
[Second Embodiment]
Now, a second embodiment of the present invention
will be described. This embodiment is the same as the
first embodiment, except a sound pressure sensor (noise
sensor) and a control method by a controller. The same
parts as the first embodiment are given the same reference
numerals for avoiding redundancy.
As shown in FIG. 12, in the second embodiment, a
sound pressure sensor noise sensor 60 is connected to the
input side of a controller 61.

- 50 -
The sound pressure sensor 60 functions to measure
a noise level (sound pressure level) that occurs in the
printing cylinders (particularly, upper blanket cylinder
9a) of each of the printing units 7, and input the result
of measurement to the controller 61.
That is, it has been found that in the case where
the tension variation Tn of the web 10 is great, great
noise occurs due to a variation in the separating position
of the web 10 and therefore the probability of delamination
occurrence is interrelated to a noise level caused by
printing. The greater the noise level, the higher the
probability of delamination occurrence.
Hence, the controller 61 handles input noise level
information as a parameter interrelated to the
delamination occurrence probability and, when the
probability is a predetermined threshold value or
greater, controls an angle adjustment mechanism (actuator)
20 to adjust the staggered angle a so that the noise level
information is reduced.
The controller 61 is constructed such that only
when a signal indicating a printing adjustment stage (e.g.,
a stage from the start of printing to the completion of
the color checking of an image to be printed) is input,
it transmits a command signal to the actuator to adjust
the staggered angle α .
The offset rotary printing machine and inclination
setting method according to the second embodiment of the

- 51 -
present invention are constructed as described above.
Accordingly, based on the noise level created by the
printing cylinder at the time of printing, the staggered
angle a can be accurately adjusted according to the
operating state of the printing machine, whereby the
occurrence of delamination can be more effectively
reduced.
In addition, when the noise level is too great,
the level is reduced and therefore noise associated with
the printing operation can also be reduced.
Besides, since the staggered angle α is adjusted
in the printing adjustment stage, a reduction in the
efficiency of the printing operation due to adjustments
to the staggered angle a can be reduced.
[Other Embodiments]
While the present invention has been described with
reference to the preferred embodiments thereof, the
invention is not to be limited to the details given herein,
but may be modified within the scope of the invention
hereinafter claimed.
For example, in the above-described embodiments,
while printing-related information and noise level have
been employed as parameters interrelated with the
probability of delamination occurrence, the present
invention is not limited to these parameters. It may
employ any parameter, so long as it interrelates with the
probability of delamination occurrence.

- 52 -
CLAIMS
1. An offset rotary printing machine which
includes a first printing cylinder (9b) and a second
printing cylinder (9a) in which printing is performed on
aweb (10) atanip (N) between the pair of printing cylinders
(9b and 9a),
the second printing cylinder (9a) contacting the
first printing cylinder (9b) and being shifted downstream
from the first printing cylinder (9b), said printing
machine comprising;
an angle adjustment mechanism (20) for adjusting
an angle ( α ) of imaginary oblique plane, which is inclined
with imaginary perpendicular plane being perpendicular
to the moving direction of the web (10) and is connecting
between each center axis of the first printing cylinder
(9b) and the second printing cylinder (9a); and
A controller (30, 61) for controlling said angle
adjustment mechanism (20), based on parameters
interrelating to a delamination occurrence probability
( ) that is caused as printing is performed by the second
printing cylinder (9a).
2. The offset rotary printing machine as set forth
in claim 1, wherein said controller (30) comprises
corresponding-relationship setting part (32) for
setting a corresponding relationship between the
delamination occurrence probability ( ) and the angle

- 53 -
( α), based on printing-related information equivalent
to the parameters which includes information on images
to be printed, information on ink used, information on
property of the web (10), and information on a support
span of the web (10) located downstream of the second
printing cylinder (9a);
optimum-range calculator (32) for calculating an
optimum range for the angle ( α) which causes the
delamination occurrence probability ( ) to be a preset
probability or less, based on the corresponding
relationship that was set by said
corresponding-relationship setting part (32); and
command part (33) for outputting a command signal
to said angle adjustment mechanism (20) to cause the angle
( α) to be within the optimum range calculated by said
optimum-range calculator (32).
3. The offset rotary printing machine as set forth
in claim 2, wherein
the image information includes a second printing
area ratio (M2) of a second image that is transferred by
the second printing cylinder (9a), and a first printing
area ratio (Ml) of a first image that is transferred by
the first printing cylinder (9b);
the ink information includes information on ink
tack (t);
the web-property information includes information

- 54 -
on rigidity (G) of the web (10);
the support span information includes information
on an inter-color length (L*) which is a distance between
the nip (N) of the pair of printing cylinders (9b and 9a)
and a next nip of a next pair of printing cylinders adjacent
to the pair of printing cylinders (9b and 9a); and
said corresponding-relationship setting part (32)
sets, as an amount interrelating to the printing-related
information, a tension variation amount (Tn) in a paper
plane which indicates a variation in tension in a width
direction of the web (10) on a downstream side of the nip
(N) of the pair of printing cylinders (9b and 9a), and
also sets the corresponding relationship so that the
tension variation amount (Tn) satisfies
= c • exp(Tn)
where represents the delamination occurrence
probability, c represent a constant, and Tn represents
the tension variation amount.
4 . The offset rotary printing machine as set forth
in claim 3, wherein the tension variation amount (Tn) is
a function of a web separating angle ( θ ) which is an angle
interrelating to the second printing area ratio (M2) of
the second image, the ink tack (t), and the angle (a)
and which is an angle of the web (10) to a surface of the

- 55 -
second printing cylinder (9a) formed as the web (10) is
separated from the surface; the rigidity (G) of the web
(10); the printing area ratio (M2) of the second image;
and a contact amount (β ) of the web (10) to a surface
of the first printing cylinder (9b) which is an amount
corresponding to the angle (α ) .
5. The offset rotary printing machine as set forth
in any one of claims 1 to 4, wherein said controller (30)
controls said angle adjustment mechanism (20) under
particular conditions in which delamination can occur.
6. The offset rotary printing machine as set forth
in claim 5, wherein the particular conditions are that
the first and second images are transferred to both sides
of the web (10); a difference between the first
printing-area ratio (Ml) and the second printing area ratio
(M2) is a preset threshold value or greater; the second
image to be transferred by the second printing cylinder
(9a) contains a nonprinting area; and a portion of the
first image which corresponds to the nonprinting area of
the first image has a printing area ratio which is a preset
value or greater.
7. The offset rotary printing machine as set forth
in claim 5 or 6, wherein the particular conditions are
that both an average of the first printing area ratio (Ml)

- 56 -
of the first image and an average of the second printing
area ratio (M2) of the second image are a first reference
value or greater.
8. The offset rotary printing machine as set forth
in any one of claims 5 to 7, wherein the particular
conditions are that the second printing area ratio (M2)
of the second image is a second reference value or greater,
and a printing area ratio of a portion of the first image
is a third reference value or greater.
9. The offset rotary printing machine as set forth
in claim 1, further comprising:
noise sensor (60) for sensing, as a parameter
interrelating to the delamination occurrence probability
() , a noise level that is generated as printing is
performed by the pair of printing cylinders (9b and 9a) ;
wherein, based on the noise level sensed by noise
sensor (60), said controller (61) controls the angle
adjustment mechanism (20) to adjust the angle (a) so that
the noise level is reduced.
10. The offset rotary printingmachine as set forth
in claim 9, wherein said controller (61) adjusts the angle
( α ) based on the noise level at an adjustment stage before
printing is performed by the pair of printing cylinders
(9b and 9a).

- 57 -
11. A method of adjusting an angle (a) of imaginary
oblique plane, which is inclined with imaginary
perpendicular plane being perpendicular to the moving
direction of a web (10) and is connecting between each
center axis of an first printing cylinder (9b) and an second
printing cylinder (9a),
the pair of printing cylinders (9b and 9a) being
equipped with an offset rotary printing machine printing
on the web (10) at a nip (N) between the pair of printing
cylinders (9b and 9a),
the second printing cylinder (9a) contacting the
first printing cylinder (9b) and being shifted downstream
from the first printing cylinder (9b), said method
comprising:
an information acquisition step of acquiring, as
parameters interrelating to a delamination occurrence
probability ( ) that is caused as printing is performed
by the second printing cylinder (9a), printing-related
information which includes information on images to be
printed, information on ink used, information on property
of the web (10) , and information on a support span of the
web (10) located downstream of the secondprinting cylinder
(9a);
a corresponding-relationship setting step of
setting a corresponding relationship between the
delamination occurrence probability ( ) and the angle

- 58 -
(a), based on the information acquired by said information
acquisition step; and
an angle setting step of setting the angle ( α ) to
a range which causes the delamination occurrence
probability () to be a preset probability or less, based
on the corresponding relationship that was set by said
corresponding-relationship setting step.
12. The method as set forth in claim 11, wherein
the image information includes a second printing
area ratio (M2) of a second image that is transferred by
the second printing cylinder (9a), and a first printing
area ratio (Ml) of a first image that is transferred by
the first printing cylinder (9b);
the ink information includes information on ink
tack (t);
the web-property information includes information
on rigidity (G) of the web (10);
the support span information includes information
on an inter-color length (L*) which is a distance between
the nip (N) of the first pair of printing cylinders (9b
and 9a) and a next nip of a next pair of printing cylinders
adjacent to the first pair; and
said corresponding-relationship setting step sets,
as an amount interrelating to the printing-related
information, a tension variation amount (Tn) in a paper
plane which indicates a variation in tension in a width

- 59 -
direction of the web (10) on a downstream side of the nip
(N) of the pair of printing cylinders (9b and 9a), and
also sets the corresponding relationship so that the
tension variation amount (Tn) satisfies
= c • exp(Tn)
where represents the delamination occurrence
probability, c represent a constant, and Tn represents
the tension variation amount.
13. The method as set forth in claim 12, wherein
the tension variation amount (Tn) is a function of a web
separating angle (θ ) which is an angle interrelating to
the second printing area ratio (M2) of the second image,
the ink tack (t) , and the angle ( α ) and which is an angle
of the web (10) to a surface of the second printing cylinder
(9a) formed as the web (10) is separated from the surface;
the rigidity (G) of the web (10) ; the printing area ratio
(M2) of the second image; and a contact amount (β ) of
the web (10) to a surface of the first printing cylinder
(9b) which is an amount corresponding to the angle (a) .
14. The method as set forth in any one of claims
11 to 13, further comprising:
a property selection step of selecting at least
either the property of the web (10) or the kind of ink

- 60 -
used, based on a corresponding relationship between at
least either the property of the web (10) or the kind of
ink used and the delamination occurrence probability ( ) ,
prior to said information acquisition step.
15. Amethod of adjusting an angle (α) of imaginary
oblique plane, which is inclined with imaginary
perpendicular plane being perpendicular to the moving
direction of a web (10) and is connecting between each
center axis of an first printing cylinder (9b) and an second
printing cylinder (9a),
the pair of printing cylinders (9b and 9a) being
equipped with an offset rotary printing machine printing
on the web (10) at a nip (N) between the pair of printing
cylinders (9b and 9a),
the second printing cylinder (9a) contacting the
first printing cylinder (9b) and being shifted downstream
from the first printing cylinder (9b), said method
comprising:
a noise sensing step for sensing, as a parameter
interrelating to a delamination occurrence probability
( ) that is caused as printing is performed by the second
printing cylinder (9a), a noise level that is generated
as printing is performed by the pair of printing cylinders
(9b and 9a); and
an angle adjustment step which, based on the noise
level sensed by noise sensing step, adjusts the angle ( α )

- 61 -
so that the noise level is reduced.
16. The method as set forth in claim 15, wherein
the angle adjustment step is carried out at an adjustment
stage before printing is performed by the pair of printing
cylinders (9b and 9a).

An offset rotary printing machine which includes
a first printing cylinder (9b) and a second printing
cylinder (9a) in which printing is performed on a web (10)
at a nip (N) between the pair of printing cylinders (9b
and 9a),the second printing cylinder (9a) contacting the
first printing cylinder (9b) and being shifted downstream
from the first printing cylinder (9b). The printing
machine includes an angle adjustment mechanism (20) for
adjusting an angle (α) of a plane connecting center axes
of the pair of printing cylinders (9b and 9a) which is
inclined to a plane perpendicular to the moving direction
of the web (10), and a controller (30, 61) for controlling
the angle adjustment mechanism (20) , based on parameters
interrelating to a delamination occurrence probability
(Φ) that is caused as printing is performed by the
downstream second printing cylinder (9a).