JP2000079674A - Printing method and printing equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a printing method and a printing equipment, with which a printing plate can be surely fixed to the outer peripheral part of a plate cylinder without annexing an extra constitution to the printing equipment. SOLUTION: In this printing equipment, after an image is recorded on printing plates, which are held on a first and a second plate cylinders 11 and 12 and no image has been recorded, and processed, the inks supplied to printing plates are transferred to a printing paper held by a impression cylinder 15 through a first and a second blanket cylinders 13 and 14 so as to execute a printing. Ink arrangements 20a and 20b and dampening arrangement 21a and 21b are arranged surrounding the first plate cylinder 11. Further, ink arrangements 20c and 20d and dampening arrangements 21c and 21d are arranged surrounding the second plate cylinder 12. The dampening arrangements 21a, 21b, 21c and 21d execute actions for supplying dampening waters to the surface of the first and the second plate cylinders 11 and 12 in order to fix printing plates to the first and second plate cylinders 11 and 12.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a printing method and a printing apparatus for printing by supplying dampening water and ink to a printing plate mounted on an outer peripheral portion of a plate cylinder.

[0002]

2. Description of the Related Art In such a printing apparatus, a holding means called a plate edge is provided on an outer peripheral portion of a plate cylinder, and an edge of a printing plate is held by the holding means. The plate is mounted on the outer periphery of the plate cylinder.

[0003]

In such a printing apparatus, when printing is continuously performed on a large number of printing papers, there is a case where a problem occurs in that the printing plate is misaligned.

[0004] In particular, when the operator manually mounts the printing plate on the outer peripheral portion of the plate cylinder, the printing plate is strongly fixed to the outer peripheral portion of the plate cylinder as holding means for holding the edge of the printing plate. A vice mechanism having a vise mechanism can be used. However, in a printing apparatus that uses a printing plate mounting mechanism for automatically mounting the printing plate on the outer peripheral portion of the plate cylinder, the fixing force of the printing plate to the plate cylinder must be smaller than that of a vise mechanism. It is not easy to obtain, and the printing plate is likely to be misaligned.

[0005] When such misalignment occurs in the printing plate, the printing quality is degraded due to a decrease in printing accuracy. Further, particularly, in a printing apparatus for printing a printing plate on a plate cylinder by recording an image on the printing plate mounted on the outer peripheral portion of the plate cylinder, and then printing using the printing plate. In the case where the printing plate is displaced from the time when the image is recorded until the time when printing is completed, the above-described deterioration in print quality becomes remarkable.

The present applicant has proposed a sheet material mounting apparatus that can prevent the above-described positional shift of the printing plate by supplying water to the back surface of the printing plate or the surface of the plate cylinder ( JP-B-3-1668). According to the sheet material mounting apparatus, the printing plate can be securely fixed to the plate cylinder with a simple configuration. However, a supply unit for supplying water to the back surface of the printing plate or the surface of the plate cylinder is provided. Need to be installed separately.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and a printing method and a printing method capable of securely fixing a printing plate to an outer peripheral portion of a plate cylinder without adding a special configuration to a printing apparatus. It is an object to provide a printing device.

[0008]

According to a first aspect of the present invention, there is provided a printing method for printing by supplying dampening water and ink to a printing plate mounted on an outer peripheral portion of a plate cylinder. A first dampening solution supply step of supplying dampening water to the surface of the plate cylinder by a device; a printing plate mounting step of mounting a printing plate on an outer peripheral portion of the plate cylinder by a printing plate mounting mechanism; A second dampening water supply step of supplying dampening water to the printing plate mounted on the outer peripheral portion of the plate cylinder by a dampening water supply device; And an ink supply step of supplying ink to the printing plate, and a printing step of printing with a printing plate supplied with dampening water and ink.

According to a second aspect of the present invention, there is provided a plate cylinder for mounting a printing plate on an outer peripheral portion thereof, and a dampening water supply for supplying dampening water to the printing plate mounted on the outer peripheral portion of the plate cylinder. A printing apparatus comprising: a printing apparatus; and an ink supply device for supplying ink to a printing plate mounted on an outer peripheral portion of the plate cylinder. A dampening solution is supplied to the surface of the body.

According to a third aspect of the present invention, there is provided a printing apparatus for performing printing by supplying a dampening solution and ink to a printing plate, comprising a holding means for holding an edge of the printing plate at an outer peripheral portion thereof. A plate cylinder, a printing plate mounting mechanism for mounting a printing plate on the outer periphery of the plate cylinder, and a dampener for supplying dampening water to the printing plate mounted on the outer periphery of the plate cylinder. A water supply device, an ink supply device for supplying ink to a printing plate mounted on the outer peripheral portion of the plate cylinder, and a printing plate mounted on the outer peripheral portion of the plate cylinder by the printing plate mounting mechanism. Control means for supplying dampening water to the surface of the plate cylinder by the dampening water supply device.

According to a fourth aspect of the present invention, there is provided a printing apparatus for performing printing by supplying a dampening solution and ink to a printing plate, comprising a holding means for holding an edge of the printing plate at an outer peripheral portion thereof. Plate cylinder, a printing plate mounting mechanism for mounting a printing plate on an outer peripheral portion of the plate cylinder, a printing plate mounting mechanism, and an image recording apparatus that records an image on a printing plate mounted on the outer peripheral portion of the plate cylinder, A dampening water supply device for supplying dampening water to a printing plate mounted on the outer peripheral portion of the plate cylinder, and an ink supplying device for supplying ink to a printing plate mounted on the outer peripheral portion of the plate cylinder And control means for supplying dampening water to the surface of the plate cylinder by the dampening solution supply device before mounting the printing plate on the outer peripheral portion of the plate cylinder by the printing plate mounting mechanism. Features.

According to a fifth aspect of the present invention, in the second aspect of the present invention, the printing plate mounting mechanism is configured to guide a leading end of the printing plate to holding means in the plate cylinder. The printing apparatus includes guide means and pressing means for pressing the printing plate held by the holding means against the surface of the plate cylinder.

[0013]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic side view of a printing apparatus according to the present invention.

This printing apparatus comprises a first and a second plate cylinder 11,
After recording an image on a printing plate having no image recorded on the plate 12 and making a plate, the ink supplied to the printing plate is applied to the impression cylinder 15 via the first and second blanket cylinders 13 and 14. The printing is performed by transferring the image to the held printing paper.

The printing apparatus includes a first plate cylinder 11 movable between a first printing position indicated by a solid line in FIG. 1 and an image recording position indicated by a two-dot chain line, and a first printing cylinder 11 indicated by a solid line in FIG. And a second plate cylinder 12 movable between the second printing position and the image recording position.

The first plate cylinder 11 moved to the first printing position
Around the printing plate, an ink supply device 20a for supplying black (K) ink to the printing plate, an ink supply device 20b for supplying magenta (M) ink to the printing plate, and a printing plate. The dampening water supply devices 21a and 21b for supplying dampening water are arranged. Further, around the second plate cylinder 12 moved to the second printing position, an ink supply device 20c for supplying, for example, cyan (C) ink to the printing plate, and a yellow (Y) ink to the printing plate, for example.
An ink supply device 20 d for supplying the ink of the present invention, a dampening solution supply device 21 c for supplying a dampening solution to the printing plate,
21d. Further, around the first plate cylinder 11 or the second plate cylinder 12 that has moved to the image recording position, a plate feeding unit 23, a plate discharging unit 24, and an image recording device 25 are provided.
And a developing device 26 are disposed.

The dampening water supply devices 21a, 21a,
1b, 21c and 21d are the first and second plate cylinders 11 and 12, respectively.
An operation of supplying dampening water to the surfaces of the first and second plate cylinders 11 and 12 is performed under the control of the control unit 140 described below in order to fix the printing plate to the printing plate.

The printing apparatus includes a first blanket cylinder 13 provided to be able to contact the first plate cylinder 11 and a second blanket cylinder provided to be able to contact the second plate cylinder 12. The impression cylinder 1 provided so as to be able to contact the cylinder 14 and the first and second blanket cylinders 13 and 14 at different positions.
5, a paper feed cylinder 16 for passing the print paper supplied from the paper feed unit 27 to the impression cylinder 15, and a chain 1 for discharging the printed print paper received from the impression cylinder 15 to the paper discharge unit 28.
9 and a blanket cleaning device 29
And

The first and second plate cylinders 11 and 12 are respectively connected to a not-shown plate cylinder moving mechanism. By driving the plate cylinder moving mechanism, the first and second printing positions described above are shifted. It reciprocates between the image recording position. Further, the first plate cylinder 11 rotates in synchronization with the first blanket cylinder 13 at the first printing position, and the second plate cylinder 12 rotates with the second blanket cylinder 14 at the second printing position. It is configured to rotate in synchronization. Further, a plate cylinder rotating mechanism (not shown) is provided in the vicinity of the image recording position, and when the first and second plate cylinders 11 and 12 are both moved to the image recording position, the plate cylinder rotates. It is configured to rotate by driving a rotation mechanism.

As described above, the image recording device 25, the plate feeding unit 23, and the plate discharging unit 24 are arranged around the first plate cylinder 11 or the second plate cylinder 12 moved to the image recording position. I have.

FIG. 2 is a schematic side view showing the image recording device 25, the plate feeding section 23 and the plate discharging section 24, and FIG. 3 is a schematic plan view of the image recording apparatus 25.

The above-described image recording device 25 uses a laser beam in the main scanning direction with respect to a printing plate that moves in the sub-scanning direction by rotation of the first plate cylinder 11 or the second plate cylinder 12 that has moved to the image recording position. The image is recorded by scanning the beam 89. The image recording device 25 includes a laser beam 8 as a recording beam modulated based on an image signal.
9, a cylindrical lens 94, a collimating lens 95, a polygon mirror 96 as a deflecting device, an fθ lens 97, two folding mirrors 98, these semiconductor laser 93, and a cylindrical lens 94. , A collimating lens 95, a polygon mirror 96, an fθ lens 97, and a housing 99 for housing a folding mirror 98.

The laser beam 89 emitted from the semiconductor laser 93 is deflected by the action of the polygon mirror 96 to become a scanning beam directed in the main scanning direction, and scans the entire printing plate as the printing plate moves in the sub-scanning direction. By doing
Record the desired image on the printing plate.

The plate supply unit 23 includes a supply cassette 63 for storing a long roll-shaped printing plate on which no image is recorded in a light-tight state, and a leading end portion of the printing plate pulled out from the supply cassette 63. Member 64 and a guide roller 65 for guiding the printing plate to the surface of the first plate cylinder 11 or the second plate cylinder 12, and a cutter 66 for cutting a long printing plate into a sheet-shaped printing plate. And In addition, the above-described plate discharge unit 24 is peeled off by the action of the claw mechanism 73 and the claw mechanism 73 for peeling the printing plate held on the first plate cylinder 11 or the second plate cylinder 12 after printing is completed. A conveyor mechanism 69 for transporting the printing plate to a discharge cassette 68 (see FIG. 1).

Further, as shown in FIG. 4, a guide member 64 surrounds the first plate cylinder 11 or the second plate cylinder 12 moved to the image recording position.
The printing plate guided on the surface of the plate cylinder 12
Alternatively, a pressing roller 130 for pressing the outer peripheral portion of the second plate cylinder 12 and a claw opening / closing mechanism 132 for opening and closing a tip claw mechanism 131 for nipping the leading end of the printing plate.
And a rear end claw mechanism 13 for holding the rear end of the printing plate.
A claw opening / closing mechanism 134 for driving the opening / closing of the printing plate 3 and a guide roller mechanism 135 for pressing the printing plate when discharging the printing plate are provided.

The above-described guide member 64 and pressing roller 130 are configured to move synchronously by driving the air cylinder 136.

That is, as shown in FIGS. 5 to 7, the guide member 64 is supported so as to be able to swing about a shaft 137. The guide member 64 is provided with an air cylinder 136.
Moving plate 138 connected to the cylinder rod of
39 are connected. For this reason, the guide member 6
4, the tip of the first cylinder 11 or the second cylinder 1 shown in FIGS.
2 reciprocates between a guide position close to the surface of FIG. 2 and a retracted position separated from the surface of the first plate cylinder 11 or the second plate cylinder 12 shown in FIG.

On the other hand, the pressing roller 130 is connected to the cylinder rod of the air cylinder 136 via a connecting member 147. When the air cylinder 136 is driven, its tip shown in FIGS. It reciprocates between a standby position separated from the surface of the first or second plate cylinder 11 and a pressing position close to the surface of the first or second plate cylinder 11 shown in FIG.

The tip claw mechanism 131 for holding the leading end of the printing plate described above is disposed on the first plate cylinder 11 and the second plate cylinder 12, respectively. This tip claw mechanism 131
As shown in FIGS. 5 to 7, the claw seat 148 provided near the surface of the first plate cylinder 11 or the second plate cylinder 12, the first arm 149 and the first arm 149 extending in different directions from each other. 2
A lever 152 swingable about a shaft 151 provided on the first plate cylinder 11 or the second plate cylinder 12, and a lever 152 disposed on the first arm 149 side of the lever 152. And a claw 153 that is provided.

At the ends of the first and second arms 149 and 150 of the lever 152, bearings 154 and 1 are respectively provided.
55 is attached. Further, as shown in FIG. 14, the lever 152 is a coil spring 1 disposed around the shaft 151.
56, and is urged by the coil spring 156 in the direction of the arrow shown in FIG. For this reason, the claw 153 provided on the side of the lever 152 on the first arm 149 side, as shown in FIG.
The tip is in contact with the claw seat 148.

As shown in FIGS. 5 to 7, the pawl opening / closing mechanism 132 for driving the opening / closing of the tip pawl mechanism 131 is located near the first plate cylinder 11 or the second plate cylinder 12 which has moved to the image recording position. And a block 159 provided at the tip of a cylinder rod 158 of the air cylinder 157. As will be described later, the lower end 161 of the block 159 moves the bearing 155 at the tip of the second arm 150 of the lever 152 when the claw 153 of the tip claw mechanism 131 is moved to the release position during printing plate supply. It functions as a pressing part for pressing. Further, as described later, the lever 152 is used to move the claw 153 of the tip claw mechanism 131 to the release position when the printing plate is discharged, as described later.
A concave portion 162 functioning as a pulling portion for pulling the bearing 154 at the tip of the first arm 149 is formed.

The rear end claw mechanism 133 for holding the rear end of the printing plate described above is disposed on the first plate cylinder 11 and the second plate cylinder 12, respectively. This rear end claw mechanism 133
As shown in FIGS. 8 to 10, a pawl seat 164 rotatable about a shaft 163 provided on the first plate cylinder 11 or the second plate cylinder 12 and a pawl seat 164 The installed shaft 165
And a coil spring 167 disposed on the pawl seat 164 and biasing the pawl 166 to rotate counterclockwise as shown in FIG. A spring 168 disposed on the first plate cylinder 11 or the second plate cylinder 12 to urge the pawl seat 164 to rotate clockwise, and a pin 171 and the first plate cylinder 11 or The cam mechanism includes a cam 173 rotatable around a shaft 172 provided on the second plate cylinder 12 and a cam follower 170 connected to the claw seat 164.

As shown in FIGS. 8 to 10, the pawl opening / closing mechanism 134 for driving the rear end pawl mechanism 133 to open and close the first plate cylinder 11 or the second plate cylinder 12 moved to the image recording position.
And an abutment member 176 provided at the tip of a cylinder rod 175 of the air cylinder 174. In addition, this contact member 1
At the tip of the air cylinder 76, as shown in FIG.
74, the first and second pressing portions 177, 1 having different heights with respect to the reciprocating movement direction of the hitting member 176.
78. Then, as described later, the first pressing portion 177 is driven by the air cylinder 174 to move the lever 169.
And the second pressing portion 178 is in contact with the air cylinder 1.
The drive of the cam 74 causes the pin 171 of the cam 173 to abut.

Next, the first plate cylinder 11 or the second plate cylinder 1
The mounting operation of the printing plate P for mounting the printing plate P on the outer peripheral portion of the printer 2 will be described with reference to FIGS. In addition, the mounting operation of the printing plate P for mounting the printing plate P on the outer peripheral portion of the first plate cylinder 11 or the second plate cylinder 12, which will be described below, includes dampening solution supply devices 21a, 21b, 21c, 21
This is executed after the operation of supplying dampening water to the surfaces of the first and second plate cylinders 11 and 12 by d.

When the printing plate P is mounted on the first plate cylinder 11 or the second plate cylinder 12, the first plate cylinder 11 or the second plate cylinder 12 is rotated by a plate cylinder rotating mechanism (not shown). As shown in FIG. 5, the claw 153 and the claw seat 148 of the tip claw mechanism 131 are moved to a position facing the guide member 64 and the pressing roller 130.

Then, as shown in FIG.
By driving the air cylinder 157 at 32, the block 159 disposed at the tip of the cylinder rod 158 is moved in the direction of the first plate cylinder 11 or the second plate cylinder 12.
As a result, the lower end 161 of the block 159 is
52, the bearing 15 at the tip of the second arm 150
Press 5. Therefore, the lever 152 swings counterclockwise as shown in FIG. 6 against the urging force of the coil spring 156 shown in FIG. 14, and is accordingly disposed on the first arm 149 side of the lever 152. Claws 153
8 to a release position remote from the surface. The movement of the block 159 is such that the lower end 161 of the block 159 is moved to the first plate cylinder 1.
Contact member 181 provided on first or second plate cylinder 12
Stops when it touches.

In this state, the pair of nip rollers 1
The printing plate P is pulled out of the supply cassette 63 by the driving of 79 (see FIG. 2). The leading end of the printing plate P pulled out from the supply cassette 63 is guided by the guide rollers 65 and the guide members 64 and moves toward the outer peripheral portion of the first plate cylinder 11 or the second plate cylinder 12. The rear end of the printing plate P is cut by the cutter 66.

As shown in FIG. 6, when the leading end of the printing plate P is guided by the guide member 64 and enters between the pawl 153 of the leading end pawl mechanism 131 and the pawl seat 148, the air cylinder 157 is formed. Driving the cylinder rod 158
Is moved in the direction away from the first plate cylinder 11 or the second plate cylinder 12. Thereby, the lever 152 is moved to the coil spring 1 shown in FIG.
Due to the urging force of 56, the first arm 149 of the lever 152 swings clockwise as shown in FIG.
The claw 153 disposed on the side moves to the clamping position where it comes into contact with the surface of the claw seat 148 via the printing plate P, as in the case shown in FIG. Is held by

In this state, the moving plate 138 and the connecting member 147 are moved downward by driving the air cylinder 136. Thereby, as shown in FIG. 7, the guide member 64 moves from the guide position shown in FIGS. 5 and 6 to the retracted position, and the pressing roller 130 moves from the standby position shown in FIGS. 5 and 6 to the pressing position. .

Then, the first plate cylinder 11 or the second plate cylinder 12 is rotated counterclockwise by a plate cylinder rotating mechanism (not shown). With the rotation of the first plate cylinder 11 or the second plate cylinder 12, the printing plate P whose leading end is clamped by the tip claw mechanism 131 is moved to the first plate cylinder 11 or the second plate cylinder 1.
2 At this time, since the pressing roller 130 presses the printing plate P toward the outer peripheral portion of the first plate cylinder 11 or the second plate cylinder 12, the printing plate P does not sag without causing any slack in the printing plate P. Can be reliably spread on the outer peripheral portion of the first plate cylinder 11 or the second plate cylinder 12.

As described above, the air cylinder 13
The configuration in which the guide member 64 is moved to the retreat position and the pressing roller 130 is moved to the pressing position by the drive of No. 6 is as follows.

That is, in order to surely convey the leading end of the printing plate P to the leading end pawl mechanism 131, it is preferable that the leading end of the guide member 64 and the leading end pawl mechanism 131 be as close as possible. Further, in order to reliably spread the printing plate P on the outer peripheral portion of the first plate cylinder 11 or the second plate cylinder 12,
It is possible to press the printing plate P, the tip of which is held by the tip claw mechanism 131, from a position immediately after the tip claw mechanism 131 toward the outer periphery of the first plate cylinder 11 or the second plate cylinder 12. preferable. Therefore, by adopting a configuration in which the guide member 64 is moved to the retracted position and the pressing roller 130 is moved to the pressing position, it is possible to prevent the guide member 64 and the pressing roller 130 from interfering with each other and to hold the printing plate P at the front end claw. The first plate cylinder 11 is surely transported toward the mechanism 131 and
Alternatively, it can be surely spread on the outer peripheral portion of the second plate cylinder 12.

The printing plate P is spread on the outer periphery of the first plate cylinder 11 or the second plate cylinder 12 by rotating the first plate cylinder 11 or the second plate cylinder 12 by a plate cylinder rotating mechanism (not shown). If the rear end of the printing plate P is located above the rear end pawl mechanism 133 as shown in FIG. 8, the rotation of the first plate cylinder 11 or the second plate cylinder 12 is stopped.

Then, the claw opening / closing mechanism 134 for opening and closing the rear end claw mechanism 133 causes the rear end claw mechanism 133 to operate.
Is opened and closed, and the rear end portion of the printing plate P is held by the rear end claw mechanism 133. This operation is performed as follows.

That is, when the claw opening / closing mechanism 134 is not operated, as shown in FIG.
The claw seat 164 in the position 33 is disposed at a position rotated clockwise by being biased by the spring 168, and the claw 166 is biased by the coil spring 167 at a position where the tip thereof abuts the surface of the claw seat 164. Are located.

In this state, when the contact member 176 is moved in the direction of the first plate cylinder 11 or the second plate cylinder 12 by driving the air cylinder 174, first, as shown in FIG. Second pressing portion 17
8 presses the pin 171 of the cam 173. As a result, the cam 173 rotates around the shaft 172 and presses the cam follower 170. For this reason, the pawl seat 164 is
It rotates counterclockwise around 63 as shown in FIG.

When the contact member 176 is further moved in the direction of the first plate cylinder 11 or the second plate cylinder 12 by driving the air cylinder 174, as shown in FIG. The pressing portion 177 presses the tip of the lever 169 connected to the pawl 166. As a result, the pawl 166 connected to the lever 169 is
10, and the tip of the claw 166 is disposed at a position separated from the surface of the claw seat 164. At this time, the printing plate P spread on the outer peripheral portion of the first plate cylinder 11 or the second plate cylinder 12 is pressed toward the surface of the first plate cylinder 11 or the second plate cylinder 12 by the pressing roller 130. As shown in FIG. 10, the rear end of the printing plate P is pressed by the pressing
6 and between the claw seat 164.

When the rear end of the printing plate P does not easily enter between the claw 166 and the claw seat 164, the rear end of the printing plate P may be pressed by high-pressure air or an actuator. Good.

Next, by driving the air cylinder 174,
The contact member 176 is connected to the first plate cylinder 11 or the second plate cylinder 1.
When the coil spring 167 is moved in a direction away from
The claw 166 is rotated counterclockwise by the action of, and becomes the same state as the state shown in FIG. For this reason, the rear end of the printing plate P is sandwiched between the pawl 166 and the pawl seat 164.

When the contact member 176 is further moved in a direction away from the first plate cylinder 11 or the second plate cylinder 12 by driving the air cylinder 174, the spring 1
The action of 68 causes the pawl seat 164 to rotate clockwise to a state similar to the state shown in FIG. For this reason, the printing plate P whose front end is held by the front end claw mechanism 131 and whose rear end is sandwiched by the claw 166 and the claw seat 164 of the rear end claw mechanism 133 rotates the claw seat 164. Accordingly, tension is applied.

Therefore, by setting the urging force of the spring 168 to an appropriate value, the pawl seat 16
By rotating the printing plate P in the direction of applying tension to the printing plate P of No. 4,
It is possible to apply a tension to the printing plate P that can withstand printing. That is, the rear end claw mechanism 133
Functions not only as a holding mechanism for holding the printing plate P but also as a tension applying mechanism for applying tension to the printing plate P.

When the mounting of the printing plate P on the first plate cylinder 11 or the second plate cylinder 12 is completed by the above operation, the first plate cylinder 11 or the second plate cylinder is driven by driving a plate cylinder rotating mechanism (not shown). The laser beam 89 modulated on the surface of the printing plate P held on the outer periphery of the first plate cylinder 11 or the second plate cylinder 12 by the image recording device 25 while rotating the second plate cylinder 12 at low speed. Irradiate and record the image.

The printing plate P mounted on the outer peripheral portion of the first plate cylinder 11 is attached to the printing plate P by the image recording device 25 as shown in FIG.
As shown in (a), an image area 67a for printing with black ink and an image area 67b for printing with magenta ink are recorded. Further, as shown in FIG. 16B, the printing plate P mounted on the outer peripheral portion of the second plate cylinder 12 has an image area 67 c for printing with cyan ink by the image recording device 25. And an image area 67d for printing with yellow ink. The image area 67a and the image area 67b are equally distributed in a state where the image area 67a and the image area 67b are attached to the outer peripheral portion of the first plate cylinder 11 (that is, 180 degrees apart from each other).
It is recorded at the position where Similarly, the image area 67c and the image area 67d are recorded at positions where they are equally distributed (that is, 180 degrees apart from each other) when mounted on the outer peripheral portion of the second plate cylinder 12. You.

In the above-described embodiment, in order to simplify the configuration of the first plate cylinder 11 or the second plate cylinder 12, etc., the first plate cylinder 11 or the second plate cylinder 12
Are provided with two image areas 67a, 67b or 67c, 67d, respectively, on one printing plate P held on the outer peripheral portion.
However, each of the first plate cylinder 11 and the second plate cylinder 12 has two sets of the front claw mechanism 131 and the rear end claw mechanism 13.
By disposing 3, the first plate cylinder 11 or the second plate cylinder 12 may be configured to hold two printing plates P. Also in this case, the image area of each printing plate P is equally distributed (that is, 18
Two printing plates P so as to be separated by 0 degrees).
Must be held on the first plate cylinder 11 or the second plate cylinder 12 in a state of being evenly distributed.

Next, the first plate cylinder 11 or the second plate cylinder 1
An operation of discharging the printing plate P from the outer peripheral portion of the printing plate P will be described with reference to FIGS.

When discharging the printing plate P used for printing from the first plate cylinder 11 or the second plate cylinder 12,
The first cylinder moved to the printing position by a plate cylinder rotating mechanism (not shown)
After rotating the plate cylinder 11 or the second plate cylinder 12 to the position shown in FIG. 11, the block 159 is driven by the air cylinder 157 in the pawl opening / closing mechanism 132 to move the block 159 to the first plate cylinder 1.
It is moved in the direction of the first or second plate cylinder 12. After a while
The first plate cylinder 11 or the second plate cylinder 1 by the plate cylinder rotating mechanism
Rotate 2 slightly clockwise.

As a result, as shown in FIG. 12, the first arm 14 of the lever 152 of the tip claw mechanism 131 is moved.
Nine tip bearings 154 are housed in recesses 162 in block 159.

Thereafter, as shown in FIG. 13, the block 159 disposed at the tip of the cylinder rod 158 is driven by driving the air cylinder 157 in the pawl opening / closing mechanism 132.
Is moved in a direction away from the first plate cylinder 11 or the second plate cylinder 12. As a result, the concave portion 162 of the block 159 is connected to the first arm 149 of the lever 152.
The tip bearing 154 is pulled.

Accordingly, the lever 152 swings counterclockwise as shown in FIG. 13 against the urging force of the coil spring 156 shown in FIG. 14, and accordingly, the lever 152 moves toward the first arm 149 of the lever 152. The pawl 153 provided is adapted to hold the pawl seat 14.
8 to a release position remote from the surface. Thereby, the printing plate P held by the tip claw mechanism 131 is
Is released. The swing of the lever 152 is caused by the contact member 18 provided at the tip of the second arm 150 on the first plate cylinder 11 or the second plate cylinder 12.
It stops when it comes into contact with 2.

Next, the guide roller mechanism 135 shown in FIG.
Is moved to a position where it contacts the printing plate P on the first plate cylinder 11 or the second plate cylinder 12 by driving the solenoid 186. Also, the claw mechanism 7
3 is moved from the standby position shown by the solid line in FIG. 4 to the peeling position of the printing plate P shown by the two-dot line by driving the air cylinder 184, and the leading end of the printing plate P is moved to the leading end claw mechanism. After being separated from the base 131, the claw 153 of the tip claw mechanism 131 is driven by driving the air cylinder 157.
Is returned to a position where it comes into contact with the surface of the claw seat 148. Thereafter, the first plate cylinder 11 or the second plate cylinder 12 is rotated counterclockwise at a low speed by driving a plate cylinder rotating mechanism (not shown).

At the position where the claw portion 183 moves between the standby position and the peeling position, the claw portion 183 is connected to the first plate cylinder 11.
A notch (not shown) is provided on the first plate cylinder 11 so as not to interfere with the surface of the first plate cylinder. Therefore, the operation of moving the claw portion 183 to the standby position is also performed at the same position of the first plate cylinder 11.

As a result, the leading end of the printing plate P held on the outer periphery of the first plate cylinder 11 or the second plate cylinder 12 is moved by the pawl 183 of the pawl mechanism 73 to the first plate cylinder 11 or the second plate cylinder. After being peeled off from the outer peripheral portion of the second plate cylinder 12, it is guided onto the conveyor mechanism 69 with the rotation of the first plate cylinder 11 or the second plate cylinder 12. The conveyor mechanism 69 is driven at the same speed as the first plate cylinder 11 or the second plate cylinder 12 by a driving device (not shown).

When the rear end claw mechanism 133 holding the rear end of the printing plate P moves to a position facing the claw opening / closing mechanism 134, the first plate cylinder 11 or the second plate cylinder 12 and the conveyor The driving of the mechanism 69 is stopped, and the pawl 166 of the rear end pawl mechanism 133 is rotated by the pawl opening / closing mechanism 134, thereby releasing the pawl 166 and the pawl seat 164 from nipping the printing plate P. At this time, the leading end of the printing plate P is
Are inserted in the pair of opposed rollers. Therefore, by subsequently restarting the driving of the conveyor mechanism 69, the printing plate P separates from the first plate cylinder 11 or the second plate cylinder 12, and is conveyed to the discharge cassette 68 (see FIG. 1) by the conveyor mechanism 69. Is done.

Referring again to FIG. 1, as described above, the ink supply devices 20a and 20b are provided around the first plate cylinder 11 moved to the first printing position. An ink supply device 20c and an ink supply device 20d are arranged around the second plate cylinder 12 moved to the second printing position. These ink supply devices 20a, 20
Each of b, 20c, and 20d (hereinafter, collectively referred to as “ink supply device 20”) has a plurality of ink rollers 71 and ink fountains 72.

The ink rollers 71 of the ink supply devices 20a and 20b perform a swing operation by the action of a cam or the like (not shown). Then, by this swinging operation, the two image areas 6 formed on the printing plate P held on the outer peripheral portion of the first plate cylinder 11 are formed.
When an ink roller 71 of the ink supply device 20a or 20b comes into contact with an arbitrary image area of 7a and 67b, ink can be supplied only to a necessary image area. Similarly, the ink supply device 20
The ink rollers 71 of c and 20d also swing by the action of a cam or the like (not shown). And, by this swinging operation,
The ink roller 71 of the ink supply device 20c or 20d comes into contact with an arbitrary image region of the two image regions 67c and 67d formed on the printing plate P held on the outer peripheral portion of the second plate cylinder 12. With this configuration, ink can be supplied only to a necessary image area.

The fountain solution supply devices 21a, 21b, 21c and 21d (when these are collectively referred to as "fountain solution supply device 21") are used before the ink supply device 20 supplies ink to the printing plate P. Then, a dampening solution is supplied to the printing plate P. Of these dampening water devices 21, the dampening water supply device 21a is an image area 67a in the printing plate P.
The dampening solution supply device 21b is in the image region 67b of the printing plate P, the dampening solution supply device 21c is in the image region 67c of the printing plate P, and the dampening solution supply device 21d is in the image region 67d of the printing plate P. Are supplied with fountain solution.

Further, the first plate cylinder 11 or the second
Prior to the mounting operation of the printing plate P to mount the printing plate P on the outer peripheral portion of the plate cylinder 12, the dampening solution supply devices 21a and 21b are provided on the surface of the first plate cylinder 11 and the dampening solution supply device 21c.
By supplying dampening water to the surface of the second plate cylinder 12, the fixing action of the printing plate P to the first and second plate cylinders 11 and 12 is further strengthened.

Below the first plate cylinder 11 or the second plate cylinder 12 that has moved to the image recording position, the above-described developing device 26 is provided. The developing device 26 has a developing unit, a fixing unit, and a diaphragm unit, and is configured to be able to move up and down between a standby position indicated by a two-dot chain line and a developing position indicated by a solid line in FIG.

When the printing plate P on which an image is recorded by the image recording device 25 is developed by the developing device 26, the plate cylinder rotating mechanism is driven to drive the printing plate P together with the first plate cylinder 11 or the second plate cylinder. The developing unit, the fixing unit, and the diaphragm unit are sequentially brought into contact with the rotating printing plate P.

The first and second blanket cylinders 13 and 14, which are provided so as to be able to contact the first and second plate cylinders 11 and 12,
It has the same diameter as the first and second plate cylinders 11 and 12, and a blanket for ink transfer is mounted on the outer periphery thereof. Then, the first and second blanket cylinders 13, 1
Reference numeral 4 denotes a configuration in which the first and second plate cylinders 11 and 12 and the impression cylinder 15 can be freely contacted and separated by a cylinder insertion mechanism (not shown).

Referring to FIG. 1 again, the blanket cleaning device 29 disposed between the first and second blanket cylinders 13 and 14 is connected to the take-up roll from the unwind roll via a plurality of pressure rollers. The cleaning liquid is supplied to a long cleaning cloth stretched on the path leading to the first and second blanket cylinders 13 and 14 and then the cleaning cloth is slid. This is for cleaning the surfaces of the second blanket cylinders 13 and 14. The cleaning cloth was applied to the impression cylinder 1
The surface of the impression cylinder 15 may also be cleaned by contacting the surface of the impression cylinder 5.

The impression cylinder 15 provided so as to be in contact with the first and second blanket cylinders 13 and 14 is provided with the first and second plate cylinders 1.
1, 12 and first and second blanket cylinders 13, 14
直径 of the diameter of Further, the impression cylinder 15 has a gripper (not shown) for holding and transporting the leading end of the printing paper.

The paper feed cylinder 16 disposed adjacent to the impression cylinder 15 has the same diameter as the impression cylinder 15. The paper feeding cylinder 16 holds and transports the leading end of the printing paper supplied one by one from the paper feeding unit 27 by a gripper (not shown) by a suction board 74 that reciprocates. The leading end of the printing paper held by the gripper is held by the gripper of the impression cylinder 15 when the printing paper is transferred from the paper feed cylinder 16 to the impression cylinder 15.

The paper discharge cylinder 17 disposed adjacent to the impression cylinder 15 has the same diameter as the impression cylinder 15. The paper discharge cylinder 17 has a structure in which a pair of chains 19 is wound around both ends, and grippers are provided on connecting members (not shown) that connect the pair of chains 19. The leading end of the printing paper held by the gripper of the impression cylinder 15 is
When the printing paper is transferred from the impression cylinder 15 to the discharge cylinder 17,
It is held by one of the grippers of the paper discharge cylinder 17. Then, the printing paper is conveyed onto the paper discharge unit 28 as the chain 19 moves and is discharged.

The paper feed cylinder 16 is connected to a drive motor via a belt (not shown). And the paper feed cylinder 1
6, the impression cylinder 15, the paper discharge cylinder 17, and the first and second blanket cylinders 13 and 14 are respectively connected by gears attached to their ends. Further, the first blanket cylinder 13 and the first plate cylinder 11 moved to the first printing position, and the second blanket cylinder 14 and the second plate cylinder 12 moved to the second printing position, As described above, they are connected by the gears 51 and 52 attached to their ends, respectively. Accordingly, by the driving of a drive motor (not shown), these paper feed cylinder 16, impression cylinder 15, discharge cylinder 17, first and second blanket cylinders 13, 14, and first and second plate cylinders 11, 12 are moved. Rotate in synchronization with each other.

FIG. 17 is a block diagram showing a main electrical configuration of the printing apparatus. This printing apparatus has a ROM 141 storing operation programs necessary for controlling the apparatus.
And a RAM 1 in which data and the like are temporarily stored during control.
And a control unit 140 including a CPU 143 for executing a logical operation. The control unit 140 includes a drive unit in the ink supply device 20, the dampening solution supply device 21, the image recording device 25, the development processing device 26, the blanket cleaning device 29, and the claw opening / closing mechanisms 132 and 134 via the interface 144. Drive circuit 1 for generating a drive signal for
45. The printing apparatus is controlled by the control unit 140, and executes a plate making operation and a printing operation described later.

Next, plate making and printing operations by this printing apparatus will be described. FIG. 18 is a flowchart showing an outline of a plate making and printing operation by the printing apparatus. Note that the printing and plate making operations are performed when multicolor printing is performed on printing paper with four color inks of yellow, magenta, cyan, and black.

First, a prepress process for recording an image on the printing plate P on the first and second plate cylinders 11 and 12 and performing a developing process is executed (step S1). This plate making process is executed according to the process shown in the flowchart of FIG. 19 as a subroutine.

That is, first, the first plate cylinder 11 is
Is moved to the image recording position indicated by the two-dot chain line (step S11).

Next, dampening water is supplied to the surface of the first plate cylinder 11 (step S12). The dampening solution is supplied by bringing the dampening solution supply rollers in the dampening solution supply devices 21a and 21b into contact with the surface of the first plate cylinder 11. The dampening solution may be supplied to the entire surface of the first plate cylinder 11 or to a part of the surface of the first plate cylinder 11. This is the same for the second plate cylinder 12 described later.

Next, the printing plate P is supplied to the outer periphery of the first plate cylinder 11 (step S13). The supply of this printing plate P is
This is executed by holding the leading end of the printing plate P pulled out from the supply cassette 63 and the trailing end of the printing plate P cut by the cutter 66 by the above-described leading-end claw mechanism 131 and rear-end claw mechanism 133. .

Subsequently, an image is recorded on the printing plate P held on the outer periphery of the first plate cylinder 11 (step S14). The image is recorded by rotating the first plate cylinder 11 at a low speed and irradiating the modulated printing laser beam to the printing plate P held on the outer periphery of the first plate cylinder 11 from the image recording device 25. Be executed.

Next, the printing plate P on which the image has been recorded is developed (step S15). In this developing process, after the developing device 26 is raised from the standby position indicated by the two-dot chain line to the developing position indicated by the solid line in FIG.
This is performed by sequentially bringing the developing unit, the fixing unit, and the diaphragm unit into contact with the printing plate P that rotates together with the printing plate P.

When the developing process is completed, the first plate cylinder 1
1 is moved to a first printing position indicated by a solid line in FIG. 1 (step S16).

Subsequently, the second plate cylinder 12 moved to the image recording position by the same operation as in steps S11 to S16.
After the dampening water is supplied from the dampening water supply devices 21c and 21d to the printing plate P, the plate making process is performed on the printing plate P held on the outer periphery of the second plate cylinder 12 (Steps S17 to S2).
2). Then, when the plate making on the printing plate P held on the outer periphery of the first and second plate cylinders 11 and 12 is completed, the plate making process is completed.

In the plate making process described above, the first and second printing plates P are mounted on the outer peripheral portions of the first and second plate cylinders 11 and 12 using the dampening solution supply device 21 before the first and second printing plates P are mounted. Plate cylinder 11, 1
Since the dampening water is supplied in advance to the surface of No. 2,
The above-mentioned front-end claw mechanism 131 and rear-end claw mechanism 133
The printing plate P is securely fixed to the outer peripheral portions of the first and second plate cylinders 11 and 12 even when the holding force of the end portion of the printing plate P due to the above is weak. Will not occur.

Referring again to FIG. 18, when the plate making process is completed, a printing process for printing on printing paper using the printing plate P on the first and second plate cylinders 11 and 12 is executed (step). S2). This printing process is performed as follows.

That is, first, each dampening solution supply device 21 is brought into contact with only the corresponding image area of the printing plate P held on the first and second plate cylinders 11 and 12. Subsequently, each ink supply device 20 is brought into contact only with a corresponding image area of the printing plate P held on the first and second plate cylinders 11 and 12. Thereby, each image area 67a, 67b, 6
7c and 67d are supplied with dampening water and ink from the corresponding dampening water supply devices 21 and ink supply devices 20, respectively. Then, the ink supplied to the printing plate P is transferred to corresponding areas of the first and second blanket cylinders 13 and 14.

Then, the printing paper is supplied to the paper feed cylinder 16. The printing paper is transferred from the paper feed cylinder 16 to the impression cylinder 15. In this state, when the impression cylinder 15 continues to rotate, the impression cylinder 15
Has a half diameter of the first and second plate cylinders 11 and 12 and the first and second blanket cylinders 13 and 14, the printing paper held on the outer peripheral portion of the impression cylinder 15 , In the first rotation, black and cyan inks,
In the second rotation, magenta and yellow inks are transferred.

In this manner, the leading end of the printing paper on which the printing of four colors has been completed is transferred from the impression cylinder 15 to the discharge cylinder 17. The printing paper on which the printing of the four colors has been completed is conveyed to the discharge unit 28 together with the gripper of the discharge cylinder 17 by the driving of the pair of chains 19 and discharged.

When the printing process is completed, the printing plate P used for printing is discharged (step S3). In order to discharge the printing plate P, first, the first plate cylinder 11 is moved to an image recording position indicated by a two-dot chain line in FIG. Then, the first plate cylinder 11 is rotated counterclockwise, and the end of the printing plate P held on the first plate cylinder 11 is peeled off by the claw mechanism 73. It is guided by 69 and discharged into the discharge cassette 68. Then, after returning the first plate cylinder 11 to the first printing position, the second plate cylinder 12 is moved from the second printing position to the image recording position, and by performing the same operation as described above, The printing plate P held on the second plate cylinder 12 is discharged into the discharge cassette 68.

When the step of discharging the printing plate P is completed, the first and second blanket cylinders 13 and 14 are cleaned by the blanket cylinder cleaning device 29 (step S4).

When the cleaning of the first and second blanket cylinders 13 and 14 is completed, it is confirmed whether or not another printing work is to be performed (step S5). To perform another printing operation, the operations of steps 1 to 4 are repeated.

When the printing operation has been completed, the ink is washed (step S6). The cleaning of the ink is performed by removing and cleaning the ink adhered to the ink roller 71 and the ink fountain 72 in each ink supply device 20 by an ink cleaning device (not shown) provided in each ink supply device 20. .

When the ink washing step is completed, all the steps are completed.

In the printing process described above, the first and second
Before mounting the printing plate P on the outer peripheral portions of the plate cylinders 11 and 12,
The first and second plate cylinders 11 using the dampening water supply device 21,
Since the dampening water is supplied to the surface of the printing plate P in advance, the printing plate P is kept in the third position even when the clamping force of the printing plate P end portion by the above-described front-end claw mechanism 131 and rear-end claw mechanism 133 is weak. The first and second plate cylinders 11 and 12 are securely fixed to the outer peripheral portions, so that the printing plate P is not displaced in the printing process.

[0097]

According to the first to third aspects of the present invention, the dampening solution supply device for supplying the dampening solution to the printing plate applies the dampening solution to the surface of the plate cylinder before the printing plate is mounted. Since the dampening solution is supplied, the printing plate can be securely fixed to the outer peripheral portion of the plate cylinder without adding a special configuration to the printing apparatus. Therefore, high-quality printing can be performed.

According to the fourth aspect of the present invention, the dampening solution supply device for supplying dampening solution to the printing plate has the surface of the plate cylinder before mounting the printing plate and performing image recording. Since the dampening water is supplied to the printing plate, the printing plate can be securely fixed to the outer peripheral portion of the plate cylinder without adding a special configuration to the printing apparatus. Therefore, it is possible to execute recording and printing of a high-quality image.

According to the fifth aspect of the present invention, the guide means for the printing plate mounting mechanism to guide the leading end of the printing plate to the holding means in the plate cylinder, and the printing plate having the leading end held by the holding means And a pressing means for pressing the printing plate against the surface of the plate cylinder, it is possible to more reliably fix the printing plate to the outer peripheral portion of the plate cylinder.

[Brief description of the drawings]

FIG. 1 is a schematic side view of a printing apparatus according to the present invention.

FIG. 2 shows an image recording device 25, a plate feeding unit 23, and a plate discharging unit 2.
FIG.

3 is a schematic plan view of the image recording device 25. FIG.

FIG. 4 is a schematic side view showing a printing plate supply and discharge mechanism.

FIG. 5 is an explanatory diagram showing a mounting operation of the printing plate P.

FIG. 6 is an explanatory view showing a mounting operation of the printing plate P.

FIG. 7 is an explanatory diagram showing a mounting operation of the printing plate P.

FIG. 8 is an explanatory diagram showing a mounting operation of the printing plate P.

FIG. 9 is an explanatory diagram showing a mounting operation of the printing plate P.

FIG. 10 is an explanatory diagram showing a mounting operation of the printing plate P.

FIG. 11 is an explanatory diagram showing a discharging operation of the printing plate P.

FIG. 12 is an explanatory diagram showing a discharging operation of the printing plate P.

FIG. 13 is an explanatory diagram showing a discharging operation of the printing plate P.

14 is a perspective view of the vicinity of a lever 152. FIG.

15 is a front view of the claw opening / closing mechanism 134. FIG.

FIG. 16 is an explanatory diagram showing an arrangement of an image area 67 on a printing plate P.

FIG. 17 is a block diagram illustrating a main electrical configuration of the printing apparatus.

FIG. 18 is a flowchart illustrating an outline of plate making and printing operations performed by the printing apparatus.

FIG. 19 is a flowchart showing a plate making process.

[Explanation of symbols]

 Reference Signs List 11 first plate cylinder 12 second plate cylinder 13 first blanket cylinder 14 second blanket cylinder 15 pressure cylinder 16 paper feed cylinder 17 paper discharge cylinder 20 ink supply device 21 dampening solution supply device 23 plate supply unit 24 Plate discharging unit 25 Image recording device 26 Developing device 27 Paper feeding unit 28 Paper discharging unit 130 Press roller 131 Tip claw mechanism 132 Claw opening / closing mechanism 133 Rear end claw mechanism 134 Claw opening / closing mechanism 135 Guide roller mechanism 136 Air cylinder P Printing plate S printing paper

Continuation of the front page (72) Inventor Yoshihito Ohara 304 Sayama Shinkaiji, Kumiyama-cho, Kuse-gun, Kyoto 1 Dainippon Screen Mfg. Co., Ltd. Kumiyama Office F term (reference) 2C020 DA04 DA10 DA11 DA12 DA13 2C034 AA14 AE22 AE27 AE42 BA02 BA07 BA11 BB03 BB43 2C250 EA07 EA10 EA23 EA29

Claims (5)

[Claims] 1. A printing method for performing printing by supplying a dampening solution and ink to a printing plate mounted on an outer peripheral portion of a plate cylinder, wherein a dampening solution supply device applies dampening solution to the surface of the plate cylinder. A first dampening solution supply step of supplying, a printing plate mounting step of mounting a printing plate on an outer peripheral portion of the plate cylinder by a printing plate mounting mechanism, and an outer peripheral portion of the plate cylinder by the dampening water supply device. A second dampening solution supply step of supplying a dampening solution to the printing plate mounted on the printer, an ink supply step of supplying ink to a printing plate mounted on an outer peripheral portion of the plate cylinder by an ink supply device, A printing step of performing printing using a printing plate supplied with dampening water and ink. 2. A plate cylinder for mounting a printing plate on an outer peripheral portion thereof,
A dampening solution supply device for supplying dampening solution to the printing plate mounted on the outer peripheral portion of the plate cylinder, and an ink supply device for supplying ink to the printing plate mounted on the outer peripheral portion of the plate cylinder A printing apparatus, comprising: a dampening solution supply device that supplies dampening solution to a surface of a plate cylinder before the printing plate is mounted. 3. A printing apparatus for performing printing by supplying a dampening solution and ink to a printing plate, comprising: a plate cylinder provided with holding means for holding an edge of the printing plate at an outer peripheral portion thereof; A printing plate mounting mechanism for mounting the printing plate on the outer peripheral portion of the cylinder, a dampening solution supply device for supplying dampening water to the printing plate mounted on the outer peripheral portion of the plate cylinder, An ink supply device for supplying ink to a printing plate mounted on an outer peripheral portion of the plate cylinder; and the dampening water supply device before mounting the printing plate on the outer peripheral portion of the plate cylinder by the printing plate mounting mechanism. Control means for supplying dampening water to the surface of the plate cylinder by means of the printing apparatus. 4. A printing apparatus for performing printing by supplying dampening water and ink to a printing plate, comprising: a plate cylinder having holding means for holding an edge of the printing plate on an outer peripheral portion thereof; A printing plate mounting mechanism for mounting a printing plate on the outer peripheral portion of the cylinder, an image recording device that records an image on a printing plate mounted on the outer peripheral portion of the plate cylinder, and an outer peripheral portion of the plate cylinder. A fountain solution supply device for supplying a fountain solution to the mounted printing plate, an ink supply device for supplying ink to a printing plate mounted on an outer peripheral portion of the plate cylinder, and the printing plate mounting mechanism And a control means for supplying dampening water to the surface of the plate cylinder by the dampening water supply device before mounting the printing plate on the outer peripheral portion of the plate cylinder. 5. The printing apparatus according to claim 2, wherein the printing plate mounting mechanism includes: a guiding unit configured to guide a leading end of the printing plate to a holding unit in the plate cylinder; A press unit configured to press a printing plate held by the holding unit against a surface of the plate cylinder.