Printing – Stenciling – Stationary-inker machines
Reexamination Certificate
2000-09-14
2001-11-06
Hilten, John S. (Department: 2854)
Printing
Stenciling
Stationary-inker machines
C101S116000, C101S119000, C101S129000
Reexamination Certificate
active
06311614
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a stencil printing machine of an inner press system in which a printing pressure is exerted from the inner circumference side of a printing drum, and also relates to a technique for preventing ink leakage from the sides of the printing drum (in the center axis direction of the printing drum).
2. Description of the Related Art
As shown in
FIGS. 1 and 2
, a printing section of a stencil printing machine is provided with a printing drum
100
and a pressure drum
101
, and the printing drum
100
and the pressure drum
101
are respectively installed so as to freely rotate, with respective portions of their outer circumferential faces being closely located with each other. The printing drum
100
is provided with a pair of cylindrical flanges (not shown) aligned face to face with each other with a predetermined gap, and a stencil sheet clamp section
100
a
, which clamps the leading edge of a stencil sheet
104
, is placed on a part of the outer circumferential face of each flange. A flexible screen
102
is stretched over the outer circumferential faces of the flanges of the printing drum
100
other than the stencil sheet clamp section
100
a.
As shown in
FIGS. 3 and 4
, the screen
102
, which forms a circumferential wall of the printing drum, consists of an area which is subjected to a pressing force applied by an inner pressing roll
106
and which is constituted by a rough mesh screen section
102
a
and a dense mesh screen section
102
b
that are overlapped with each other so as to form a pressing-time ink passage section
112
(indicated by a diagonal hatched portion in
FIG. 3
) through which ink
103
is only allowed to pass upon application of the pressing force, and an area which is not subjected to the pressing force and which is formed by the rough mesh screen section
102
a
to which a coating material is injected so as to provide an ink non-passage section
113
(indicated by a cross hatched portion in
FIG. 3
) through which no ink
103
is allowed to pass even upon application of the pressing force. All the circumferential portion of the dense mesh screen section
102
b
is affixed to the rough mesh screen section
102
a
through a bonding section
102
c
formed by using the coating material injected to the rough mesh screen section
102
a
as a bonding agent. On the inner circumferential face of the screen
102
as well as on the ink non-passage section
113
located on one of the outer circumferential sides of the pressing-time ink passage section
112
, a raised portion
114
a
is formed, and on the other outer circumferential side that is rotation-delay side of the ink non-passage section
113
of the pressingtime ink passage section
12
, a raised portion
114
b
is formed. In other words, on the Inner circumferential face of the screen
102
, the raised portions
114
a
and
114
b
are formed in a U-letter shape.
Moreover, an inner press mechanism
105
is installed inside the screen
102
forming the circumferential wall of the printing drum
100
. The inner press mechanism
105
is provided with an inner pressing roll
106
, and this inner pressing roll
106
is formed on a roll support member
107
so as to freely rotate thereon. This roll support member
107
is supported so as to freely pivot centered on a support shaft
108
so that the inner pressing roll
106
is allowed to shift between a pressing position at which the inner pressing roll
106
is allowed to press the inner circumferential face of the screen
102
with the roll support member
107
being pressed in the direction of arrow a in
FIG. 2
, and a stand-by position at which the inner pressing roll
106
is apart from the inner circumferential face of the screen
102
with the roll support member
107
being rotated in the direction of arrow b in FIG.
2
. The inner pressing roll
106
is located at the pressing position at the time of printing and is also located at the stand-by position in cases other than the printing process.
Moreover, a doctor roll
109
and a driving rod
110
are respectively installed on the roll support member
107
. The doctor roll
109
has a column shape, and is secured to the roll support member
107
in the vicinity of the inner pressing roll
106
. The driving rod
110
is supported on the roll support member
107
so as to freely rotate thereon and is placed in an upper space that is formed by the outer circumferential faces of the inner pressing roll
106
and the doctor roll
109
on the respective sides located close to each other. Ink
103
is supplied to this upper space from an ink supplying section, not shown.
Next, an explanation will be given of the outline of the printing operation in succession. A stencil sheet
104
is subjected to a stencil making process by forming perforations in predetermined positions thereof, and the leading edge of the stencil sheet
104
thus subjected to the stencil making process is clamped by a stencil sheet clamp section
100
a
of the printing drum
100
, and attached to the outer circumferential face of the screen
102
forming the circumferential wall of the printing drum
100
. Next, the printing drum
100
and the pressure drum
101
are rotated in a direction indicated by an arrow in
FIG. 1
in synchronism with each other. Moreover, at the time of printing, the inner pressing roll
106
is allowed to press the screen
102
, and in this pressing state, the inner pressing roll
106
is rotated following the printing drum
100
. Ink
103
, which has passed through the gap against the doctor roll
109
, is allowed to adhere to the outer circumferential face of the inner pressing roll
106
, and the adhering ink
103
is successively transferred onto the inner circumferential face of the screen
102
by the rotation of the inner pressing roll
106
. Moreover, the screen
102
is expanded to the outer circumferential side by the pressing force of the inner pressing roll
106
so that the screen
102
is made in contact with the pressure drum
101
.
In this state, as shown in
FIG. 1
, a sheet of printing paper
111
is transported to the gap between the printing drum
100
and the pressure drum
101
, and the sheet of printing paper
111
is successively transported by the printing drum
100
and the pressure drum
101
.
The printing paper
111
, transported between the printing drum
100
and the pressure drum
101
, is further transported while being pressed between the inner pressing roll
106
and the pressure drum
101
together with the screen
102
and the stencil sheet
104
. This pressing force allows the ink
103
on the screen
102
side to be transferred onto the printing paper
111
side through the perforations of the stencil original paper
104
so that a printing process in accordance with an image formed on the stencil sheet
104
is carried out.
In the above-mentioned printing operation, the inner pressing roll
106
supplies ink
103
to the inner circumferential face of the screen
102
, and also presses the screen
102
so as to exert a pressing force thereon, while pressing the raised portions
114
a
of the screen
102
at both of the ends of the inner pressing roll
106
so that side leakage of the ink
103
(ink leakage in the center axis direction of the printing drum) is prevented.
More specifically, as shown in
FIG. 5
, some of the ink
103
located between the inner pressing roll
106
and the rough mesh screen section
102
a
is not allowed to escape outwards in the axial direction of the inner pressing roll
106
, since the inner pressing roll
106
presses the raised portions
114
a
so as to form a closely contact state between the inner pressing roll
106
and the raised portions
114
a
. Some of the ink
103
located between the rough mesh screen section
102
a
and the dense mesh screen section
102
b
is blocked in its shift outwards in the axial direction of the inner pressing roll
106
by a bonding section
102
c
so that it is not allowed to escape in the axial direction of the inne
Nakayama Koji
Ogata Masaharu
Berkowitz Marvin C.
Crenshaw Marvin P.
Hilten John S.
Nath Gary M.
Nath & Associates PLLC
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