Sheet feeding or delivering – Feeding – By means to convey sheet
Reexamination Certificate
2002-07-12
2004-04-20
Walsh, Donald P. (Department: 3653)
Sheet feeding or delivering
Feeding
By means to convey sheet
C271S194000, C271S196000
Reexamination Certificate
active
06722652
ABSTRACT:
BACKGROUND OF THE INVENTION
(1) Field of the Invention
The present invention relates generally to an intermediate cylinder for a sheet-fed press, and more particularly to an intermediate cylinder which is installed after a printing unit to adjust the traveling posture of a sheet being fed from the printing unit so that the sheet is stably conveyed. This invention also relates to a sheet-fed press with such an intermediate cylinder.
(2) Description of the Related Art
A wide variety of perfecting presses have lately been proposed and put to practical use.
FIG. 9
illustrates a perfecting press of a type where one-color printing is performed on both sides of a sheet
4
. This press includes a reverse-side printing unit
1
disposed on the upstream side of a sheet traveling path along which the sheet
4
is traveled, and an obverse-side printing unit
2
disposed on the downstream side of the sheet traveling path.
In addition to the reverse-side printing unit
1
and the obverse-side printing unit
2
, the sheet-fed press further includes a sheet feeder
19
, a feeder board section
20
, two intermediate cylinders
3
a
,
3
b
installed between the reverse-side printing unit
1
and the obverse-side printing unit
2
to convey the sheet
4
to the downstream side, a paper discharge unit
21
, and so on.
The paper discharge unit
21
is constructed of a sheet conveyor
22
, a sheet stacker
23
provided under the downstream end of the sheet conveyor
22
, and so on.
The sheet feeder
19
is provided with a paper feed table
30
on which sheets
4
to be printed are stacked, and is operative to feed the uppermost sheet
4
in accordance with consumption speed (mechanical speed) when printing is performed. The sheet
4
fed by the sheet feeder
19
is conveyed by the feeder board section
20
to a first guide cylinder
24
disposed in the introducing portion of the reverse-side printing unit
1
.
The sheet
4
is delivered from the first guide cylinder
24
to a second guide cylinder
25
and to the press cylinder
5
a
of the reverse-side printing unit
1
, in which printing is performed on the reverse side of the sheet
4
. Subsequently, the sheet
4
is conveyed by first and second intermediate cylinders
3
a
,
3
b
and delivered to the press cylinder
5
b
of the obverse printing unit
2
, in which printing is performed on the obverse side of the sheet
4
.
As shown in
FIG. 11
, the printing unit
2
(or
1
) includes an ink reservoir
31
, an ink roller group
32
, a plate cylinder
34
with a printing plate
33
wound thereon, a blanket cylinder
35
, a press cylinder
5
, a wetter
36
, and so on. The ink
18
supplied to the ink reservoir
31
is kneaded to the desired degree through the ink roller group
32
and transferred to the printing plate
33
. The ink
18
is further transferred as an image to the outer peripheral surface of the blanket cylinder
35
.
At the same time, wetting water is supplied to the blanket cylinder
35
from the wetter
36
. Thereafter, the image transferred to the blanket cylinder
35
is transferred to the surface of the sheet
4
being traveled through the gap between the blanket cylinder
35
and the press cylinder
5
. In this way, a predetermined printing is completed.
In
FIG. 9
, while the single reverse-side printing unit
1
and the single obverse-side printing unit
2
are shown, there is also a multiple color press in which a plurality of reverse-side printing units
1
and/or obverse-side printing units
2
differing in ink color are juxtaposed along the sheet traveling direction. In either case, the number of printing units
1
,
2
is determined according to circumstances.
The printed sheet
4
is conveyed from the press cylinder
5
b
of the second printing unit
2
to the sheet conveyor
22
of the paper discharge unit
21
. And the printed sheet
4
is gripped and conveyed onto the sheet stacker
23
by a chain gripper provided in an endless chain
28
being driven by a paper discharge shaft
27
, and is stacked on the paper discharge table
29
of the sheet stacker
23
. Subsequently, if a fixed quantity of sheets are stacked, then they are removed from the paper discharge table
29
,
After printing is performed on the reverse side of the sheet
4
, the ink
18
on the reverse side is dried at the outer peripheral surface of the second intermediate cylinder
3
b
by the first drier
17
disposed near the intermediate cylinder
3
b
. After printing is performed on the obverse side of the sheet
4
, the ink
18
on the obverse side is dried by the second drier
17
when the sheet
4
is being gripped and conveyed by the gripper of the endless chain
22
which travels along the outer peripheral surface of the paper discharge shaft
27
from the press cylinder
5
b.
Most of the sheet-fed presses use ink that is dried and hardened by ultraviolet rays (UV). Therefore, UV driers for irradiating ultraviolet rays are often installed. However, it is desirable to install driers in accordance with the characteristics of ink used.
In the prior art sheet-fed press constructed as described above, the drying effect of the drier
17
is not sufficiently obtained at the second intermediate cylinder
3
b
which conveys the sheet
4
to the obverse-side printing unit
2
after printing is performed by the reverse-side printing unit
1
. Because of this, poor drying such as uneven drying will occur, or the printing surface will be stained or scored.
The inventors have made various investigations and experiments and found that the above-described problems result mainly from flap of a sheet against an intermediate cylinder.
(1) The sheet
4
is conveyed with the front end gripped by the pawl member
26
of the intermediate cylinder
3
. As shown in
FIG. 10
, means to control the posture of the sheet
4
is not present on the tail side of the sheet
4
, and consequently, the sheet tail is free to move. Because of this, during conveyance, the sheet tail is separated from the surface (outer peripheral surface) of the intermediate cylinder
3
by the centrifugal force caused by rotation of the intermediate cylinder
3
and gravity. As a result, flap of the sheet
4
against the intermediate cylinder
3
is caused and the traveling posture of the sheet
4
becomes unstable.
(2) Because of the flap of the sheet
4
against the intermediate cylinder
3
, the drying effect of the drier
17
is not sufficiently obtained and therefore there is a possibility that poor drying such as uneven drying will occur.
(3) If the sheet
4
is separated from the intermediate cylinder
3
because of centrifugal force, etc., the separated rear end portion will make contact with the drier
17
, and consequently, the printing surface will be stained or scored.
(4) For the above-mentioned reasons, printing quality is considerably reduced and therefore there are cases where a great number of sheets are damaged.
In Japanese Utility Model Publication No. HEI 2-5951, there is disclosed a paper sending cylinder that sends a sheet to various cylinders on the downstream side while holding the sheet by suction. The paper sending cylinder is equipped with (1) an air tank provided in the cylinder end thereof, (2) a plurality of suction ducts held in fluid communication with the air tank and extending in the axial direction of the paper sending cylinder and provided so that they differ in phase in the circumferential direction, and (3) suction bores formed from the suction ducts to the outer peripheral surface of the paper sending cylinder. By actuating an external suction unit connected with the air tank, a sheet can be held on the outer peripheral surface of the paper sending cylinder by suction through the suction bores.
In the paper sending cylinder, shutter plates are inserted between the air tank and the suction ducts. A plurality of shutter plates are previously prepared. Each shutter plate has a through hole that is aligned with one of the suction ducts differing from one another. If a suitable shutter plate of the shutter plates is selected and used, a predetermined suction d
Dejima Kazutada
Hirose Hitoshi
Kobayashi Shin'ya
Armstrong Kratz Quintos Hanson & Brooks, LLP
Kohner Matthew J.
Mitsubishi Heavy Industries Ltd.
LandOfFree
Sheet-fed press and intermediate cylinder for sheet-fed press does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Sheet-fed press and intermediate cylinder for sheet-fed press, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Sheet-fed press and intermediate cylinder for sheet-fed press will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3255259