Printing – Rolling contact machines – Rotary
Reexamination Certificate
2001-02-28
2002-09-10
Yan, Ren (Department: 2854)
Printing
Rolling contact machines
Rotary
C101S183000
Reexamination Certificate
active
06446554
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a sheet-fed printing press that is capable of selectively printing on a single side or both sides of a sheet, and more particularly, a cam-surface switching mechanism that is capable of selectively switching the cam surface, through which the driving of turn-over grippers on a sheet turn-over drum is controlled for switching to a single-side printing operation or a both-side printing operation.
2. Discussion of the Background
A sheet-fed printing press of the type is known in, for example, Japanese Examined Patent Publication (Kokoku) No. SHO-56-2017.
In the sheet-fed printing press according to the above-cited publication, a sheet transfer unit, as illustrated in
FIG. 8
, is provided between an upstream printing unit and a downstream printing unit so as to transfer sheets
1
from an impression cylinder (not shown) of the former to an impression cylinder
4
of the latter. Aligned in sequence from the upstream to the downstream of the sheet transfer unit are a transfer drum (not shown), a storage drum
2
and a turn-over drum
3
. The sheets
1
printed at the upstream impression cylinder are transferred to the turn-over drum
3
via the transfer drum and the storage drum
2
.
The turn-over drum
3
includes turn-over grippers
7
adapted to grip the leading or trailing edge of each sheet
1
. The turn-over grippers
7
are constructed so that the sheet
1
is gripped through the associated operation of two gripping members
8
and
9
in each turn-over gripper
7
. The thus constructed turn-over grippers
7
are pivotable around the pivoting axis extending parallel to the rotational axis of the turn-over drum
3
, and have different functions respectively for a single-side printing operation and a both-side printing operation.
Specifically, in the single-side printing operation as illustrated in
FIG. 9
, the turn-over grippers
7
grip the leading edge of the oncoming sheet
1
at a tangential point A or a sheet receiving point between the storage drum
2
and the turn-over drum
3
, enabling the turn-over drum
3
to receive the sheet
1
from the grippers
5
of the storage drum
2
. The turn-over grippers
7
then rotate along with the turn-over drum
3
with maintaining their sheet gripping states, and transfer the sheet
1
to the impression cylinder
4
at a tangential point B or a sheet delivery point between the turn-over drum
3
and the impression cylinder
4
. Then, the turn-over grippers
7
are pivoted through a predetermined angle according to the vectors
81
before reaching the tangential point A to be brought into a position as illustrated in
FIG. 9
, at which they grip the oncoming sheet
1
.
On the other hand, in the both-side printing operation as illustrated in
FIG. 10
, following to the grippers
5
of each set on the storage drum
2
passing the tangential point A with maintaining their sheet gripping states, a corresponding sheet suction device
6
subsequently reaches the tangential point A at which the turn-over grippers
7
grip the trailing edge of the sheet
1
, enabling the turn-over drum
3
to receive the sheet
1
from the storage drum
2
. The grippers are then pivoted about the pivoting axis through about 180 degrees downstream with respect to the rotational direction of the turn-over drum
3
for the turning-over of the sheet
1
, and then reach the tangential point B relative to the impression cylinder
4
. The grippers
7
then deliver the sheet
1
, which has been turned over, to the impression cylinder
4
at this point, and are pivoted through about 180 degrees towards upstream with respect to the rotational direction of the turn-over drum
3
to again have the free ends facing upstream at the tangential point A relative to the storage drum
2
.
The turn-over grippers
7
performing the opening and closing actions, and the pivoting action each have the first gripping member
8
and the second gripping member
9
, as described above. Specifically, the first gripping member
8
is firmly secured to a gripper shaft
10
having the common pivoting axis around which the grippers are pivoted, while the second gripping member
9
is firmly secured to a gripper tube
11
disposed coaxially on the gripper shaft
10
for supportingly receiving the gripper shaft
10
. Gears
12
are respectively mounted on a first end of the gripper shaft
10
and a second end of the gripper tube
11
in meshing engagement with segment gears
13
disposed on the axially opposite sides of the turn-over drum
3
.
The segment gears
13
are respectively supported on rotational pins
14
of the turn-over drum
3
, and include cam followers
15
for driving the grippers. On the inner sides of a pair of flames
17
aligned at the axially opposite sides of the turn-over drum for supporting a drum shaft
16
of the turn-over drum
3
are respectively secured control cams
18
each having a torus shape with a hole defined therein through which the drum shaft
16
extends. Each control cam
18
has an outer circumference forming cam surfaces being engageable with a corresponding cam follower
15
. Hence, the rotation of the turn-over drum
3
causes the cam followers
15
to respectively travel around the outer circumferences of the control cams
18
, as sliding along the corresponding cam surfaces. Thus, the circumferential travel of the cam followers on the cam surfaces causes the segment gears
13
to travel around the rotational pins
14
, so that the gripper shaft
10
and the gripper tube
11
are rotated via the gears
12
, and hence the first gripping members
8
and the second gripping members
9
are controlled independently of each other.
Since the motion of the turn-over grippers
7
during the both-side printing operation is different from that during the single-side printing operation, the outer circumference of each control cam
18
forms two different cam surfaces arranged adjacent to each other along the axis of the turn-over drum
3
. Specifically, the cam surfaces on each control cam
18
are respectively for the single-side printing operation and the both-side printing operation. Accordingly, the cam surfaces to be engaged with the corresponding cam followers
15
are selectively switched so as to adapt the motions of the first and second gripping members
8
,
9
to the respective printing operations.
The switching of each cam surface is performed by manually displacing a corresponding cam follower
15
along the rotational center thereof, or along the axis of the turn-over drum
3
, as represented in chain double-dashed line of FIG.
12
. The same switching operation is performed at the opposite sides of the turn-over drum.
The thus arranged sheet-fed printing press requires a manual switching operation for the switching of the cam surfaces. To omit such a troublesome operation, attempts have been made to automatically perform the switching operation as disclosed in, for example, Japanese Unexamined Patent Publication (Kokai) No. HEI-07-24998. Specifically, this citation proposes the arrangement that, instead of the cam followers
15
, the control cams
18
are displaced in the axial direction of the turn-over drum
3
, which arrangement will be discussed in detail below with reference to FIG.
13
.
The description will be made mainly for the switching mechanism at the right-hand side of the turn-over drum, since the switching mechanism of the opposite side of the turn-over drum is identical in structure thereto.
The drum shaft
16
of the turn-over drum
3
is supported by the flame
17
via a cylindrical bearing
19
whose part inwardly protrudes from the flame
17
and has an outer circumference on which the control cam
18
is loosely mounted in such a manner as to be displaceable in the axial direction of the turn-over drum
3
. An air cylinder
20
for the displacement of the control cam
18
is disposed on the outer side of the flame
17
to generate the driving force in the vertical direction of the air cylinder
20
or the direction orthogonal to the
Perkins Coie LLP
Ryobi Ltd.
Yan Ren
LandOfFree
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