Printing – Flexible-sheet-securing devices
Reexamination Certificate
1999-09-20
2001-05-29
Hilten, John S. (Department: 2854)
Printing
Flexible-sheet-securing devices
C101S477000
Reexamination Certificate
active
06237491
ABSTRACT:
CROSS-REFERENCE TO RELATED APPLICATIONS
This application is based on Application No. Hei 10-266530 filed on Sep. 21, 1998 in Japan, the content of which is incorporated hereinto by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an apparatus for positioning a printing plate to a plate cylinder of a printing machine and, more specifically, to a positioning apparatus for carrying out positioning of the printing plate to the plate cylinder by contacting a fore-end of the printing plate to a reference member provided on a clamping base of the plate cylinder.
2. Description of the Prior Art
FIG. 15
shows a sectional side elevation of a plate cylinder
45
. The plate cylinder
45
is rotatably supported with a plate cylinder shaft
45
J to a body of a printing machine. A printing plate
10
is disposed on an outer surface of the plate cylinder
45
.
In order to dispose the plate
10
on the cylinder
45
, the operator of the printing machine initially inserts a leading edge side part
10
a
of the plate
10
into a gap formed between a leading edge side clamping base
51
and a leading edge side clamp
52
, then the leading edge side part
10
a
is clamped therebetween by closing the leading edge side clamp
52
.
Next, the plate
10
is rolled around the outer surface of the cylinder
45
, and then a tail edge side part
10
b
of the plate
10
is inserted between a tail edge side clamping base
53
and a tail edge side clamp
54
. The tail edge side part
10
b
is clamped therebetween by closing the tail edge side clamp
54
. Thereafter, the plate
10
is fitted tightly on the outer surface of the cylinder
45
by pulling the tail edge side part
10
b
as a result of moving both the tail edge side clamping base
53
and the tail edge side clamp
54
.
In order to carry out appropriate printing work, the plate
10
needs to be disposed on the outer surface of the cylinder
45
with accuracy. To do that, cut-out parts
10
S for positioning are formed at two separate positions on the leading edge side part
10
a
of the plate
10
as depicted in FIG.
14
. Two separate positioning pins
11
responsive to the cut-out parts
10
S are provided to the leading edge side clamping base
51
of the cylinder
45
in fixed manner as shown in FIG.
16
.
Further, a temporal fixer
20
depicted in
FIG. 16
is provided to the clamping base
51
. The temporal fixer
20
is made of a thin metal plate and the fixer
20
is arranged such that a part adjacent to a fore-end thereof is in contact with an upper surface
51
F of the clamping base
51
.
The operator carries out positioning of the plate
10
accurately by contacting cut-out planes
13
of the cut-out parts
10
S (
FIG. 14
) with the positioning pins
11
while inserting the leading edge side part
10
a
between the fixer
20
and the upper surface
51
F with force when the leading edge side part
10
a
is inserted between the leading edge side clamping base
51
and the leading edge side clamp
52
.
The fixer
20
has elasticity because it is made of a thin metal-plate. The elasticity thereof allows the fixer
20
to fix the leading edge side part
10
a
between the fixer
20
and the upper surface
51
F under a temporarily basis. The leading edge side part
10
a
is clamped between the leading edge side clamping base
51
and the leading edge side clamp
52
by closing the leading edge side clamp
52
as a result of rotating a cam (not shown) with a spanner and/or similar tool(s) under the condition described above.
Another conventional apparatus for positioning a printing plate is disclosed in Japanese patent laid-open publication No. Hei 6-286112. The overall mechanisms of the apparatus are shown in FIG.
17
. In the conventional apparatus, the leading edge side part
10
a
is inserted between the leading edge side clamping base
51
and the leading edge side clamp
52
as a result of suspending the printing plate
10
downwardly to the plate cylinder
45
with the apparatus.
A cylinder
26
is provided with to a safety cover
28
for a printing unit, and a pair of cover arms
23
are connected to the cylinder
26
through a link mechanism
27
. A protection cover
22
is suspended and held by the cover arms
23
. A shaft
24
is provided to the cover arms
23
so as to cross therebetween, and a stopper
21
is provided on the shaft
24
.
In the normal state, the protection cover
22
is positioned adjacent to the safety cover
28
. The protection cover
22
is moved to the position shown in
FIG. 17
by actuating the cylinder
26
. Thereafter, the leading edge side part
10
a
is inserted between the leading edge side clamping base
51
and the leading edge side clamp
52
while contacting the tail edge side part
10
b
to the stopper
21
. At that time, guide rollers
25
provided on the protection cover
22
support the printing plate
10
. The leading edge side part
10
a
is clamped to the leading edge side clamping base
51
and the leading edge side clamp
52
is closed by closing the leading edge side clamp
52
under the condition depicted in FIG.
17
.
The conventional apparatuses for positioning a printing plate, however, have the following problems to be solved. In order to dispose the plate
10
on the cylinder
45
at a proper position, the cut-out planes
13
of the cut-out parts
10
S need to be accurately contacted with the positioning pins
11
provided to the leading edge side clamping base
51
as two separate pins.
The cut-out planes
13
possibly contact with the positioning pins
11
in insufficient ways because the leading edge side part
10
a
is inserted between the fixer
20
and the upper surface
51
F with force. Uneven contact of the cut-out planes
13
to the positioning pins
11
makes diagonal placement of the printing plate
10
on the plate cylinder
45
possible. Consequently, printing accuracy may be decreased as a result of diagonal images caused by the diagonal placement.
There is a high probability to deform the cut-out planes
13
as a result of giving too much force thereto when the operator tries hard to contact the cut-out planes
13
with the positioning pins
11
sufficiently. Consequently, printing accuracy may also be decreased as a result of diagonal images caused by the deformation of the cut-out planes
13
.
As described above, printing accuracy may be decreased as a result of difficulties of disposing the printing plate
10
on the cylinder
45
at a proper position when the apparatus depicted in
FIG. 16
in which the leading edge side part
10
a
being fixed under a temporarily basis, is used. It requires the operator to be skillful in order to dispose the printing plate
10
at a proper position.
In the apparatus shown in
FIG. 17
, the leading edge side part
10
a
can not be inserted between the leading edge side clamping base
51
and the leading edge side clamp
52
with force because the leading edge side part
10
a
is inserted therebetween by its weight or flexure thereof. In this way, the apparatus employs a mechanism in which the cut-out planes
13
just contact with the positioning pins
11
while not employing the fixer
20
depicted in FIG.
16
.
The printing plate
10
might be held under a condition that a part adjacent to the leading edge side part
10
a
comes up from the upper surface
51
F of the clamping base
51
. The leading edge side part
10
a
moves its position to an axis of the positioning pins
11
(vertical direction in
FIG. 16
) when the leading edge side clamp
52
is closed as a result of pushing force thereof. Consequently, printing accuracy may be decreased as a result of diagonal images caused by its diagonal placement.
In addition, the apparatus shown in
FIG. 17
requires many parts such as the cylinder
26
, the link mechanism
27
, the cover arms
23
, the protection cover
22
, the guide rollers
25
and so on. Consequently, complex mechanisms are needed, and the printing plate
10
is supported in an unstable manner.
OBJECTS AND SUMMARY OF THE INVENTION
It is an object of the present invention
Hidera Masazumi
Yasuhara Yoshihiro
Grohusky Leslie J.
Hilten John S.
Merchant & Gould P.C.
Ryobi Ltd.
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