JP2532285B2 - Method for early stabilization of color tone in offset printing press - Google Patents

Description

The present invention relates to a method for stabilizing the color tone of a printed matter printed by an offset printing machine at an early stage.

(Prior Art) In an offset printing machine, water and ink are respectively supplied to a plate cylinder through a dampening roller and a large number of ink rollers, and ink and the like are temporarily supplied from the plate cylinder to a blanket cylinder (blanket cylinder). Printing is performed by transferring the sheet to be printed, which has been transferred to the blanket cylinder and the impression cylinder, in a pressure contact state. When performing multicolor printing, a printing unit having the above-described configuration is provided in multiple stages for each color, and the paper to be printed is sequentially transferred to these multistage printing units to sequentially print each color. Is being printed.

By the way, the above-mentioned offset printing machine is provided with an automatic cleaning device for the blanket cylinder to ensure the quality of the printed matter, and the blanket cylinder is regularly cleaned, but such cleaning is performed. After printing, when printing, the balance of ink and water on the surface of the blanket cylinder of each printing unit is disturbed, and as a result, the color tone of the printed matter becomes unstable. That is, for example, after washing, even if an appropriate amount of ink is supplied and printing is performed in the first color printing unit, if the printed matter is sent to the next printing unit for the second or third color, In the printing of the color, the ink adhered to the printing surface is reversely transferred to the blanket cylinders for the second and third colors, so that less than the proper amount of ink remains in the finished print, and the print has a weak color tone. It had to be something. Further, such a phenomenon similarly occurs at the time of the first printing after starting the printing machine.

In such a case, conventionally, the amount of ink reversely transferred to the blanket cylinder of the subsequent printing unit reaches a certain amount,
Since there was no choice but to idle the paper and wait until the color tone of the printed matter became stable, a considerable number of sheets (15 to 25 sheets) in the meantime
It was supposed to cause the loss of paper. Moreover, since the blanket cylinder is washed frequently as described above,
Each time such losses occur, the number of wasted sheets reaches a considerable number.

On the other hand, in order to deal with such a problem that occurs at the time of printing, an experienced operator, based on his own experience and intuition, quickly fills the ink rollers of all the printing units with ink based on his own experience and intuition to achieve early color tone. In some cases, stability is aimed at.

(Problems to be Solved by the Invention) After cleaning the blanket cylinder or at the first printing after the printing machine is started, waiting for the color tone of the printed matter to stabilize naturally causes too much paper loss. However, in the method in which the operator pre-fills the ink roller with a large amount of ink, the operator has to rotate all the printing units, and the quantity of the built-up ink is not constant at that time, so that the quality is stable. It's difficult to get a print.

The present invention has been made to solve the above problems, and reduces the occurrence of color unevenness during the first printing after the blanket cylinder washes without manual labor, thereby stabilizing the quality of printed matter. It is an object of the present invention to obtain an early method of stabilizing the color tone in an offset printing machine that can reduce paper loss.

(Means for Solving the Problem) In the present invention, at the time of printing such as after cleaning the blanket cylinder, the amount of ink reversely transferred to the blanket cylinder of the subsequent printing unit is increased in advance to increase the ink of each printing unit. It is based on the knowledge that the color tone can be stabilized early by automatically supplying the color to the roller. That is, the method for stabilizing color tone early in the offset printing machine according to the present invention is an offset printing machine in which each color is sequentially printed by a multi-stage printing unit, in which the ink roller of each printing unit is printed before printing during blanket cylinder cleaning. The feature is that the amount of ink set according to the number of subsequent printing units and the pattern area of the printed matter is automatically supplied as an increment.

(Operation) When cleaning the blanket cylinder, for example, by using the start signal of the automatic cleaning device, the amount of ink set to the ink roller of each printing unit before printing is set according to the number of subsequent printing units and the pattern area of the printed matter. Ink is automatically supplied as an increment. As a result, it is possible to reduce the occurrence of uneven color tone during printing, stabilize the color tone at an early stage, and reduce paper loss.

(Example) Hereinafter, an example is described based on drawings.

FIG. 1 is an overall structural view of an offset printing machine according to an embodiment of the present invention, FIG. 2 is a structural view of essential parts of the same embodiment, and FIG. 3 is a system diagram of the same embodiment.

In this embodiment, the printing press 1 is composed of four printing units 2 arranged in a line, and a paper feed section 3 and a paper ejection section 4 are arranged at both ends thereof. Then, a large number of sheets 5 stacked in the sheet feeding unit 3 are guided from the upper side to the printing unit 2 one by one via the feeder board 6, and after each color is printed in each printing unit 2, they are ejected. It is sent to the paper unit 4 and stacked.

Each printing unit 2 includes an ink fountain 7 arranged at an upper position, and a large number of ink roller groups 9 for supplying the ink 7a in the ink fountain 7 to a lower plate cylinder 8. The ink fountain 7 contains therein the ink 7a and also has a plurality of open / close keys 7b arranged in the width direction at intervals with respect to an original roller 9a described later. These open / close keys 7b can be opened / closed individually, so that the density can be adjusted in the width direction. Further, the ink roller group 9 includes a source roller 9a for supplying the ink 7a from the ink fountain 7, a main roller 9b arranged at a distance from the source roller 9a, and a space between the source roller 9a and the main roller 9b. A kneading roller 9c, which reciprocates to transfer ink from the original roller 9a to the main roller 9b, and a large number of continuous rollers arranged between the main roller 9b and the plate cylinder 8 for uniformly kneading the ink. Made of Laura 9d. On the other hand, at the lateral position of the plate cylinder 8, dampening water is applied.
A water tank 10 and a dampening roller 11 for supplying the water are provided.

A blanket cylinder 12 around which a rubber blanket is wound is in contact with the plate cylinder 8, and an impression cylinder 13 is arranged in contact with the blanket cylinder 12. In the figure, 14 is the impression cylinder 13 of each printing unit 2.
It shows an intermediate barrel arranged in between.

In such a configuration, printing for each color in each printing unit 2 is performed as follows.

First, dampening water is given to the surface of the plate cylinder 8 by the dampening roller 11. After that, the ink 7a in the ink fountain 7 is transferred from the original roller 9a to the main roller 9b via the calling roller 9c by the rotation of the ink roller group 9, and is supplied to the plate cylinder 8 after passing through a number of kneading rollers 9d. It Then, the ink supplied to the surface of the plate cylinder 8 is temporarily removed from the blanket cylinder.
After being transferred to the surface of 12, the blanket cylinder 12 and the impression cylinder 13
Printing is performed by being transferred to the sheet 5 passing between the sheet and the sheet.
At this time, the amount of ink supplied is variable depending on the rotation speed of the original roller 9a.

In the printing machine 1 as described above, as described in detail below, the increased amount of ink is supplied to the ink roller group 9 while the blanket cylinder 12 is being cleaned by the automatic cleaning device. Supply of increased ink control device 15
Is controlled by.

That is, as shown in FIG. 3, the control device 15 includes a blanket cylinder cleaning device control unit 16, a programmable controller 17, and a timer 18 for each printing unit, and the programmable controller 17 is a blanket cylinder cleaning device. Receiving a blanket cylinder cleaning device start-up signal from the device control unit 16 and controlling a signal to each printing unit timer 18, and receiving this signal, each printing unit timer
18 is configured to control the operation of the ink roller group 9 of each printing unit 2.

In such a control device 15, first, the operator sets the time for operating the calling roller 9c in the ink roller group 9 of each printing unit 2 by using the timer 18 for each printing unit that is collectively attached to each printing unit. I do. The set time is set in advance according to the number of print units subsequent to each two print units and the pattern area of the printed matter.

When cleaning the blanket cylinder 12, the operator presses the start button of the blanket cylinder cleaning device (not shown).
When the ON operation is performed, the programmable controller 17 which receives a signal from the blanket cylinder cleaning device control unit 16 sends a control signal to the timer 18 for each printing unit. In response to this control signal, each printing unit timer 18 starts counting time and sends an operation signal to the calling roller 9c which constitutes a part of the ink roller group 9 of each printing unit 2. As a result, each calling roller 9c starts operating and supplies the increased amount of ink to the kneading roller 9d side. Then, when the set time of each printing unit timer 18 has elapsed, each calling roller 9c is stopped, and the supply of ink for the increased amount is completed.
After that, when the cleaning of the blanket cylinder 12 is completed, printing is started by a normal procedure.

As described above, during the blanket cylinder cleaning, a predetermined amount of the increased amount of ink is automatically supplied to the ink roller group 9 of each printing unit 2 in advance for a certain period of time before the printing is resumed, so that the transfer amount of the ink to the blanket cylinder 12 is early. In addition, the balance between water and ink can be quickly obtained, and the color tone of the printed matter can be stabilized early.

In the above embodiment, the programmable controller 17 is operated by turning on the start button of the blanket cylinder cleaning device, but this is provided with another switch regardless of the cleaning device, for example, the printer start-up. It may be manually operated by manually operating the switch.

(Advantages of the Invention) Since the present invention is configured as described above, in an offset printing machine, the occurrence of color tone unevenness at the time of printing, such as after blanket cylinder washing, can be reduced without requiring manpower, and the color tone of a printed matter can be reduced. Can be stabilized at an early stage, which can stabilize the quality of printed matter and reduce paper loss.

[Brief description of drawings]

FIG. 1 is an overall structural view of an offset printing machine according to an embodiment of the present invention, FIG. 2 is a structural view of essential parts of the same embodiment, and FIG. 3 is a system diagram of the same embodiment. 1: printing machine, 2: printing unit, 9: ink roller group, 12: blanket cylinder.

Claims (1)

(57) [Claims] 1. An offset printing machine in which each color is sequentially printed by a multi-stage printing unit, according to the number of printing units following the ink roller of each printing unit and the picture area of a printed matter before printing when printing a blanket cylinder. A method for early stabilization of color tones in an offset printing machine, which is characterized in that the amount of ink set in advance is automatically supplied as an increased amount.