JPH09141836A - Calibration of damping water supply quantity of offset printing press - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accurately control the supply amt. of damping water while accurately perform mechanical adjustment and to prevent printing trouble by comparing the measured value of quantity of damping water with the set value of water supply quantity and adjusting a damping water supply device so that these values become the relation of a linear equation. SOLUTION: The quantity of damping water on the printing plate of an offset printing press and the measured value is compared with the set value of water supply quantity and the damping water supply device of the printing press is adjusted so that both values become the relation of a linear equation. That is, the quantity of damping water of a plate 1 corresponding to a damping water dial is measured by a moisture meter 11 to be compared with the set value by a comparison circuit and, if calibration by mechanical adjustment is necessary, the nips between the plate 1 and rollers 2-5 are adjusted by the nip adjusting device of a water supply apparatus and the nips between the plate 1 and ink rollers 2, 6-10 are adjusted by an ink roller adjusting device.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for calibrating an amount of dampening water on a plate surface of an offset printing machine so as to be appropriate.

[0002]

2. Description of the Related Art Offset printing is a printing method in which printing is performed by using a printing plate in which a portion corresponding to an image area is an oil-sensitive surface and a portion corresponding to a non-image area is a hydrophilic surface. That is, ink is attached to the oil-sensitive surface, dampening water is attached to the hydrophilic surface, and printing is performed by utilizing the mutual repulsion action of the ink and dampening water. At this time, it is important to supply the ink and the dampening water to the plate surface in a proper balance, and if the dampening water is supplied too much, the emulsification of the ink becomes severe and the transfer failure occurs.
On the other hand, if the dampening water is too little, the ink adheres to the non-image area, causing stains.

In order to maintain the balance between the ink and the dampening water, the adequacy of the ink dampening water additive, which is a main material in printing, has been earnestly studied, and the printing machine has been improved. The above print failure is caused even by a subtle balance defect that is thought to be caused by poor adjustment of environment or hardware / software, and it has not been solved yet. For this reason, in recent years, for example, JP-A-2-47062, JP-A-4-21286, and JP-A-5-193 have been proposed.
Japanese Laid-Open Patent Publication No. 118 describes that the emulsification behavior of an ink on a printing machine is measured online by utilizing a laser beam, a dielectric constant and a microwave. In addition, JP-A-5-20848
Japanese Patent Publication No. 1 discloses that the amount of dampening water on the plate surface is measured and adjusted so that a predetermined dampening water is supplied. Japanese Patent Publication No. 6-11538 discloses that the amount of dampening water on the plate surface is measured by using light.

Although efforts have been made to elucidate the behavior of ink and dampening water on the printing press as described above, the feedback to the printing press has not been made so that the printing press itself is finely adjusted on a daily basis. If it does not, normal printing cannot be performed because the state of water rising changes even if the roller deteriorates. For example, FIG. 1 shows the relationship between the dampening water supply dial of the printing press and the amount of dampening water on the printing plate. When the printing press is adjusted normally, a linear relationship such as A is established, but if the adjustment is not correct, the dampening water supply dial amount and the dampening water amount on the plate surface are as primary as B and C. The relationship does not show, and even if the water dial is raised even if stains occur in such a case, the dampening water on the plate surface does not change accordingly, so the problem cannot be solved and offset printing becomes more difficult. Making things happen everyday.

[0005]

SUMMARY OF THE INVENTION The present invention provides a method for investigating, comparing, and calibrating faults in a printing press to prevent printing faults due to misalignment. .

[0006]

That is, the present invention is to measure the amount of dampening water on a printing plate of an offset printing machine and compare the measured value with the set value of the dampening water supply amount to obtain the above measured value. The present invention relates to a method for calibrating the dampening water supply amount of an offset printing machine, wherein the dampening water supply device of the printing press is adjusted so that the dampening water supply amount set value has a linear relationship.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION As means for measuring the amount of dampening water on a printing plate, infrared absorption characteristics, reflectance by light rays,
It is not particularly limited as long as it can be used with a device generally used for moisture measurement, but it is compact and stable, reliable, durable, etc. so that it can be attached to a printing machine and it will not interfere with normal work. An infrared moisture meter is more preferable because an excellent one is desirable. To compare the amount of dampening water supplied to the printing press with the amount of dampening water on the printing plate, manually or automatically determine the amount of water on the printing plate when changing the dampening water supply dial of the printing press in steps or continuously. This is done by measuring with a moisture measuring device. The amount of dampening water on the plate surface at this time does not necessarily have to be an absolute amount, and may be a relative value according to the moisture meter used. An object of the present invention is to finally establish a relation of a linear expression as shown in A of FIG. 1 between the dampening water dial (set value) and the plate surface dampening water amount.

In order to calibrate the dampening water supply amount and the dampening water amount on the printing plate so as to have a linear relationship, the result of comparison between the measured dampening water amount and the dampening water supply amount is calculated by the linear expression. By adjusting the roller nip of the printing press so that The adjustment parts of the printing press are 1) water supply device, 2)
The target is the ink kneading roller device. As a water supply device, there are generally an intermittent water supply system and a continuous water supply system.The intermittent water supply system is represented by Molton, which is composed of a combination of metal rolls and rolls covered with fibers.The continuous water supply system is Dahlgren and many others. Devices have been developed, all of which consist of a combination of metal or plastic rolls and rubber rolls. The amount of dampening water is adjusted manually or automatically by adjusting the nip between the rollers of the water supply unit and the nip between the watering roller and the plate. The ink kneading roller device consists of multiple rubber rollers and metal or plastic rollers, but the amount of dampening water can be adjusted manually or automatically by adjusting the nip between the application roller and the application roller. Made by adjusting.

FIG. 2 shows the procedure for calibrating the dampening water supply amount of the offset printing machine according to the present invention. First, the amount of dampening water on the plate surface is measured by changing the dampening water supply dial. This step is repeated several times to obtain the relationship between the dial amount and the plate dampening water amount. If the relationship between the two is not a linear relationship, the nip adjustment of the water supply unit and the ink roller unit is performed individually or in conjunction, and the relationship between the dampening water supply dial amount and the plate surface dampening water amount is determined. This is repeated until the relation of the linear expression as shown in A of FIG. FIG. 3 is an explanatory diagram showing a method of calibrating dampening water according to the present invention. If the amount of dampening water of the plate 1 corresponding to the dampening water dial is measured by a moisture meter 11 and compared, and if calibration by mechanical adjustment is necessary, between the plate 1 and rollers 2 to 5 by a water supply device nip adjusting device. The nip of the plate 1, the ink rollers 2 and 6 to 10 is adjusted by the nip and the ink roller adjusting device.

[0010]

As described above, the method for calibrating the dampening water supply amount of the offset printing machine of the present invention provides a method for scientifically grasping the ink dampening water balance of offset printing, which has been difficult to understand in the past. It became possible to accurately adjust the dampening water supply amount and machine adjustment that depended on experience.

[Brief description of the drawings]

FIG. 1 is a graph showing the relationship between the amount of dampening water supply dial (set value) and the amount of dampening water on the printing plate.

FIG. 2 is a flow chart illustrating a procedure of a method of calibrating the dampening water supply amount.

FIG. 3 is an explanatory view of a dampening water supply amount calibration device.

[Explanation of symbols]

 1 Plate cylinder 2 Watering roller 2, 6, 7, 8 Inking roller 9, 10 Inking roller 11 Infrared moisture meter

Claims (1)

[Claims] 1. A dampening water amount on a printing plate of an offset printing machine is measured, and the measured value and a dampening water supply amount set value are compared to determine the measured value and the dampening water supply amount set value. A method for calibrating the dampening water supply amount of an offset printing machine, characterized in that the dampening water supply device of the printing machine is adjusted so that and have a linear relationship.