JPH04316849A - Damping control method for printer serving also as paper plate - Google Patents

Abstract

PURPOSE:To prevent to the utmost scumming and spoilage from occurring by increasing a damping quantity especially a damped quantity on a start of printing also to perform paper plate printing under an excellent damping state by a method wherein a rotary speed of a water fountain roller is increased higher than that in ordinary printing by controlling a nip pressure prior to the start of printing. CONSTITUTION:Before starting printing a nip pressure between a water distributing roller 5 and a water fountain roller 2 is set to be changed so that a delivery quantity of dampening water becomes more than that for a PS plate. When feed of printing paper is started prior to an actual start of printing, a rotary speed of a drive motor for the water fountain roller 2 is increased higher than that in ordinary printing by a motor speed switching means, and a dipping out quantity of damping water is increased greater than that in ordinary printing. The dipping out quantity of dampening water is increased by high speed rotation, and a form roller 6 is moved by control to abut against the water fountain roller 2 of which the delivery quantity has been also increased under a more gentle nip pressure. After holding sufficiently dampening water, the form roller 6 abuts against a printing plate 8 also, supplies dampening water, and printing is started.

Description

[Detailed description of the invention]

0001

[Field of Industrial Application] The present invention relates to an offset printing machine that can serve as a printing plate for both an aluminum-based PS plate and a paper-based paper plate, and in particular, it relates to an offset printing machine that can be used as a printing plate for both an aluminum-based PS plate and a paper-based paper plate. Regarding control method.

0002

BACKGROUND OF THE INVENTION Offset printing utilizes the property that ink and dampening water repel each other, and uses a printing plate on which lipophilic printed areas and hydrophilic non-printed areas are formed. It supplies ink and dampening water, transfers the image area to which ink is selectively adhered to a rubber cylinder, and then transfers this image area to paper. PS plates made of treated aluminum base materials are often used.

However, in recent years, the level of demand for printed matter has not been so severe, and for small-lot printing, so-called direct printing, in which the base material is water-resistant paper and plate making is performed using an electrophotographic method, has become increasingly popular. Paper plates have come into use, and these paper plates have the advantage of low plate material costs and platemaking costs.

[0004] By the way, printing with a paper plate has a temporary and convenient character that is done during a so-called full-scale printing with a PS plate, and therefore it is necessary to use a printing machine exclusively for paper plates and a moisture supply. There is a strong desire to use the printing press and humidifier for PS plates as they are, rather than installing additional equipment.

[0005] However, in printing using paper plates, P
Compared to the case using the S plate, it is necessary to increase the amount of moisture supplied. This is based on the difference in the structure of the plates themselves, and also because printing stains are likely to occur in the case of paper plates. Furthermore, in the case of paper plates, it is required that the moisture content at the beginning of printing be greater than that during normal printing. This is because non-print areas, where ink should not be attached, are easily stained by ink, and once the non-print areas are stained,
This is because troublesome cleaning work is required, and a large amount of waste paper is generated due to dirt, and in extreme cases, the print may be discarded.

[0006]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems and provides an advanced moisture supply control method for a printing press for paper plates. The purpose of the present invention is to perform optimal moisture supply control for paper plates while utilizing a device, prevent stains and paper waste, and eliminate the need for cleaning work.

[0007]

[Means for Solving the Problems] To this end, the present invention provides a water fountain roller which is immersed in a water boat in which dampening water is stored and is driven and rotated to draw out the dampening water, and a water fountain roller. a metering roller that is rotated in contact with the water base roller and adjusts the amount of dampening water sent out by the water base roller, and a swimsuit roller that is in contact with and separated from the water base roller and the printing plate and supplies dampening water to the printing plate. In a paper plate and printing machine having , the rotational speed of the drive motor of the water base roller is increased compared to that during normal printing to increase the amount of dampening water pumped out, and after printing starts, the rotational speed is lowered to that during normal printing. .

[0008]

[Function] As a result, the amount of moisture supplied during normal printing can be increased, and the amount of moisture supplied especially at the beginning of printing can be increased, so that paper plate printing can be performed in a good moisture condition.

[0009]

Embodiments Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a control flowchart showing an embodiment of the moisture supply control method for a paper plate printing press according to the present invention, and FIG. 2 is a diagram showing an example of a control circuit for realizing the humidity supply control method. 3(a) to 3(d) are explanatory diagrams of the operation of the humidifying device using the same humidifying control method.

First, the humidity control method for paper plates according to the present invention and the humidity control method for PS plates to be compared are shown in FIGS. 3(a) to 3(d). I will borrow and briefly explain.

[0011] In both the PS version and the paper version, there is no essential difference in the roller group of the dampening device, and the dampening water is pumped out into the water tank (1) in which dampening water is stored. The water base roller (2) for this is immersed, and this water base roller (2)
is driven and rotated by a drive motor indicated by reference numeral (3) in FIG. The drive motor (3) can be speed-changed by a motor speed switching means (4) using an inverter circuit or the like.

A metering roller (5) which is a free roller is brought into contact with the water base roller (2) under a predetermined nip pressure, and this nip pressure is adjusted by mechanical means.
The amount of dampening water sent out by the water source roller (2) is adjusted. By the way, mechanical means for changing the setting of the nip pressure of the metering roller (5) are already well known, and in the end, the contact pressure between the two rollers (2) and (5) is changed using a spring or the like. It is something.

The dampening roller (6) is controlled to move in a timed manner to receive the measured amount of dampening water sent out by the water source roller (2), and to receive the metered dampening water sent out by the water source roller (2), and to apply the dampening water to the printing plate wound around the plate cylinder (7). Edition (8
). Note that the reference numeral (9) indicates an ink forming roller of an inking device that supplies ink to the printing plate (8).

Based on the above premise, moisture supply control for the PS plate is as follows. First, in FIG. 3(a), all the roller groups of the moisture supply device are stopped, and at this time, the nip pressure of the metering roller (5) against the water source roller (2) is applied to the machine for PS plate printing. is set. Next, when the conveyance of the paper to be printed starts, the water base roller (2) starts rotating and starts pumping out the dampening water, and the water base roller (2)
The amount of dampening water to be delivered is metered by the metering roller (5) which is rotated accordingly. Then, the metered dampening water is transferred to the dampening roller (6) whose movement is controlled so as to come into contact with the water source roller (2) (b), and subsequently, this dampening roller (6) is moved to the printing plate ( 8) (Mutsuya, PS version) is also rotated to supply dampening water (c). After this,
The ink forming roller (9) of the inking device also comes into contact with the printing plate (8) to supply ink, and printing begins (d).
.

In contrast to the moisture supply control for PS plates as described above, the moisture supply control method for paper plates according to the present invention is as follows. In addition, in the method of the present invention, the moisture supply device itself is essentially the same as that for PS plates, but
The composition of both dampening solutions is completely different.

First, by operating the changeover switch (10) (shown in FIG. 2) provided on the operation stand of the printing press (not shown), the humidity control to be performed from now on is set to P.
Select whether it is for the S version or the paper version (
S1 in Figure 1). The selection made by the changeover switch (10) is determined by the determination means (12) of the computer device (11) also provided in the operation stand.

[0017] Then, a control program for the paper version (1
If 3) is selected (S2), the following control program is executed. (Incidentally, the code (14) in Figure 2 indicates the control program for the PS version, and S3 in Figure 1 is
The selection stage of the PS version program is shown. )

0018
] In the humidity control method for paper plates, before printing starts (
In Figure 3(a)), the metering roller (5) and the water base roller (2) are shown.
The nip pressure between the
). Specifically, such a switching setting is performed when the nip pressure is P
This is achieved by adjusting the mechanical means, such as a spring, which biases the metering roller (5) in the direction of the water fountain roller (2) more slowly, so that it is less than in the case of the S plate.

[0019] Then, prior to the start of actual printing, when the feeding of the paper to be printed is started (S5), the drive motor of the water head roller (2) is controlled by the motor speed switching means (4). The rotational speed (3) is increased compared to that during normal printing, and the amount of dampening water pumped out is increased compared to that during normal printing (S6). Here, normal printing refers to when printing by the paper plate continues for a certain period of time and becomes stable, and rotating the water base roller (2) at high speed at the start of paper feeding in this way is for the beginning of printing. This is to keep the moisture content of the paper plate higher during printing than during normal printing.

[0020] The swimsuit roller (6) is controlled to move to the water base roller (2), which has an increased amount of dampening water pumped out due to high-speed rotation, and an increased amount of sent out dampening water under a gentler nip pressure. (FIG. 3(b)) (S7), and after holding the dampening water sufficiently, it also comes into contact with the printing plate (8) and supplies dampening water (FIG. 3(c)) ( S8).

Then, the ink forming roller (9) also comes into contact with the printing plate (8) (FIG. 3(d)) (S9), and the preparation for printing is completed, and the paper is supplied here (S10). Actual printing is started (S11).

After that, when printing by the paper plate becomes stable, the rotational speed of the drive motor (3) of the water head roller (2) becomes as follows.
The pumping amount that was lowered to that during normal printing and increased especially at the beginning of printing is also returned to the normal pumping amount (
S12).

[0023]

[Effects of the Invention] According to the dampening control method for a paper plate printing press according to the present invention, the nip pressure between the metering roller and the water source roller is adjusted before printing starts, and the dampening water is controlled. At the same time, before printing starts, the rotational speed of the water base roller drive motor is increased higher than during normal printing to increase the amount of dampening water pumped out, and after printing starts, the rotational speed is increased. By lowering the amount of moisture to that during normal printing, it is possible to increase the amount of moisture supplied during normal printing, and also increase the amount of moisture moistened especially at the beginning of printing.
Therefore, paper plate printing can be performed in a good moisturized state, and stains and paper waste can be prevented as much as possible.

[Brief explanation of drawings]

FIG. 1 is a control flowchart showing an embodiment of a moisture supply control method for a paper plate printing press according to the present invention.

FIG. 2 is a diagram showing an example of a control circuit for realizing the humidity supply control method.

FIG. 3 is an explanatory diagram of the operation of the humidification device using the same humidification control method.

[Explanation of symbols]

1: Mizifune 2: Mizumoto roller 3: Drive motor 4: Motor speed switching means 5: Measuring roller 6: Swimsuit roller 8: Printing plate 10: Selector switch 12: Discrimination means 13: Paper version control program

Claims (1)

[Claims] Claims: 1. A water fountain roller (2) that is immersed in a water bucket (1) in which dampening water is stored and is driven and rotated to draw out the dampening water; A metering roller (5) rotates and adjusts the amount of dampening water sent out by the water base roller (2), and a metering roller (5) that is brought into contact with and separated from the water base roller (2) and the printing plate (8) to distribute the dampening water to the printing plate. In a paper plate printing machine having a swimsuit roller (6) that supplies the plate (8), the nip pressure between the adjustment roller (5) and the water base roller (2) is adjusted before printing starts. , the amount of dampening water sent out is increased, and before printing starts, the rotational speed of the drive motor (3) of the water source roller (2) is made higher than during normal printing, and the dampening water is A moisture supply control method characterized by increasing the pumping amount and decreasing the rotational speed to that during normal printing after printing starts.