JPH03190732A - Dampening apparatus of offset press - Google Patents

Abstract

PURPOSE:To eliminate the printing inferiority due to the adhesion of water or ghost and to make working environment sanitary by eliminating the malodor in a printing process by making reverse the rotary direction of a water applying roller and that of a water fountain roller at a contact place. CONSTITUTION:Doctors 14, 16 are respectively provided to the peripheral surface of a water fountain roller 13 whose lower part is immersed in the water of a water fountain (water tray) 15 on the getting-into and getting-out sides thereof. Further, the rotary direction of a water applying roller 11 and that of the water fountain roller 13 at a contact place are made reverse. Therefore, it is prevented that a water film is squeezed into the nip of the rollers 11, 13 or a water sump is formed between both rollers. As a result, the uniform water film on the water fountain roller 13 is transferred to the water applying roller 11 as it is and the addition of a surfactant or alcohols for uniformizing the thickness of the water film becomes unnecessary.

Description

[Detailed description of the invention] [Industrial usage] The present invention relates to an offset printing press.

[Conventional technology]

In offset printing, which prints while humidifying the plate surface,
There are printing defects called water marks, where traces of the humidifying water film appear in fine streaks on the printing surface, and printing defects called ghosting, where the earlier image on the plate appears faintly on the later image. may occur.

In order to eliminate such printing defects, a method of adding surfactants or alcohols to the water supplied to the printing plate has been adopted. No. 62-32051 and JP-A No. 63-137
No. 47, etc. are disclosed.

(Problems to be solved by the invention) However, surfactants and alcohols (isopropyl alcohol) added to water emit odors and are harmful to health, and their addition increases the cost of printed matter and also makes swimsuits more expensive. When the roller 11 is vibrated left and right, a large amount of water accumulates at both ends 20, and the left and right vibrations no longer work effectively to eliminate course l-.

[Purpose of the invention]

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to effectively eliminate printing defects caused by water spots and ghosts, and to prevent odor from occurring during printing.

[Structure of the invention]

The dampening device for an offset printing press according to the present invention includes:
Doctors 14 and 16 are used for the submersion example and the submergence and collapse of the water base roller peripheral surface 13 whose lower part is immersed under the water surface of the water base (water boat) 15.
It is characterized in that the rotation directions of the swimsuit roller II and the swimsuit roller 13 at the contact point are opposite to each other.

The water roller 13 is prepared by applying hard chrome plating to the surface and performing precision polishing, and the swimsuit roller 11 is made of oil-resistant rubber (for example, Rhinohyde Metrinok with a rubber hardness of 25 degrees; trademark used by Techno Roll Co., Ltd.). Prepare by coating.

The water head roller 13 is configured so that its speed can be adjusted independently.
9, ink foam roller 17, ink pie break
It is preferable to drive the ○-ra 18 etc. with a motor separate from the motor of the printing press main body that moves NA.

Alternatively, the water head roller 13 and the doctors 14 and 16 are preferably carried by a swinging arm and moved toward the swimwear roller 11 and brought into contact after the water head roller 13 begins to rotate. The original roller attachment/detachment mechanism is appropriately designed.

For the left and right vibration of the swimsuit roller 11, Japanese Patent Laid-Open No. 62-3205
Known methods disclosed in No. 1, Japanese Patent Application Laid-Open No. 63-13747, etc. are commonly used.

Doctor I4/1G is prepared by using a wear-resistant engineering plastic (for example, TI polymer; trademark used by Toshi Co., Ltd.) and polishing the tip very precisely.

(Effects of the Invention) According to the present invention, the doctor 14 in the case of diving under the water surface,
The floating ink and dirt particles transferred from the plate surface 19 through the swimsuit roller 11 and attached thereto are removed from the water base roller peripheral surface 13 to make it smooth, and the doctor 16 that comes out from below the water surface cleans the water. Since the water film on the peripheral surface 13 of the water base roller, which appears in the form of vertical stripes due to surface tension and centrifugal force due to rotation, is smoothed, the water film is thin and has a uniform thickness from end to end.

Then, since the rotation direction at the contact point between the water base roller 13 and the swimsuit roller 11 is reversed, the rotation direction between those rollers is
・A water film is not squeezed in 13 or a puddle 21 is formed.

Therefore, the uniform water film on the water base roller is directly transferred to the swimwear roller, and there is no need to add surfactants or alcohols to make the water film thickness uniform.

In this way, the thickness of the drainage film transferred to the circumferential surface of the swimsuit roller becomes uniform, so even if the swimsuit roller II is vibrated from side to side, the excess water 22 will be squeezed out to the end 20 of the water source. There is no need for the water 22 to adhere to both ends of the swimwear roller that vibrates from side to side and be drawn into the center of the printing plate.

In this way, the amount of water supplied to the plate surface 19 becomes uniform from end to end, and the left-right vibration of the bathing roller becomes effective in eliminating coast printing defects.

As described above, the present invention is effective in eliminating printing defects caused by water spots and ghosts, eliminates bad odors in the printing process, makes the working environment sanitary, and reduces printing costs, so it is practical.

[Brief explanation of drawings]

FIG. 1 is a side view of main parts of an off-cent printing machine according to the present invention;
FIG. 2 is a perspective view of the main parts of a conventional dampening device. 11.- Swimsuit roller, 13.. Mizumoto roller,
I4...Doctor 15...Mizumoto (Mizifune)
, 16... Doctor 17... Ink foam roller, 18... Ink vibrator roller, 19... Plate cylinder (plate surface), 20... Both ends, 21... Water pool,
Eclipse: Excess water.

Claims (1)

[Claims] In a dampening device for an offset printing press that supplies and humidifies a water film on the peripheral surface 13 of the water source roller 13 pumped up from the water source 15 via the swimsuit roller 11, the lower part is the water surface of the water source 15. Doctors 14 and 16 are attached to each of the submerged side and the submerged side of the water base roller peripheral surface 13 that is immersed below, and the swimsuit roller 11 and water base roller 13 at the contact points are attached.
An offset printing press dampening device characterized in that the rotation direction is opposite to that of the dampening device.