JPH1158672A - Dampening water supply apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an apparatus capable of partially adjusting the supply amt. of dampening water corresponding to that of ink and capable of keeping the optimum emulsification balance. SOLUTION: In a dampening water apparatus 600 of an offset printer consisting of at least a water tray 20, a water fountain roller 21, a water transfer roller 19 and a water applying roller 22, dampening water adjusting mechanisms 10 equipped with dry air or humidified air spraying means provided in the almost same number as the number of ink keys 31 and suction means for discharging such air are arranged.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dampening solution supply device for offset printing, and more particularly, to a mechanism for adjusting a dampening solution amount.

[0002]

2. Description of the Related Art Conventionally, many printing troubles due to dampening water have been known in offset printing, and particularly troubles due to excessive application of dampening water have occurred. This means that in actual printing, there are cases in which there are many characters or many patterns to be printed, so that the ink amount is partially adjusted (adjustment of the ink key), but the dampening water amount also corresponds. Ideally, the emulsification balance of the ink should be kept constant. However, in reality, the adjustment of the dampening solution is partially difficult and is not currently performed. Therefore, the amount of dampening solution is excessively applied to the portion having a small amount of ink in order to adjust the amount of dampening solution according to the portion having a large amount of ink (to prevent the occurrence of printing stains). This is one example, but because print operators tend to over-apply dampening solution to avoid print smearing.

[0003] Examples of such troubles due to excessive dampening solution include roller baldness (the ink does not adhere to the ink roller and the printing density decreases due to the insufficient amount of ink transfer), and the printing plate remains (the printing plate loses ink due to water loss). Ink that has lost fluidity accumulates on it and the ink does not get on it, which lowers the print density), ghost (a shadow appears on a part of the picture due to loss of ink), and dampening water Blistering due to drying delay or shortage of printed matter due to excess (the picture part becomes blistered with the dryer of the offset rotary press), back cracking / cracking (after drying, the paper breaks when folded by the folding machine) , Chalking (the printed matter after drying will fall into chalk powder any time), set-off (the ink on the printing surface will be That) other phenomena, too numerous to mention, such as abrasion defects and gloss shortage of printed matter.

[0004] The cause of such a dampening water excess phenomenon will be described below. As shown in FIG. 1, a conventional offset printing press employs an ink fountain (3) for temporarily storing ink (50).
0) and a watercraft (20) for storing dampening water (60). The ink (50) and the fountain solution (60) reach the plate surface (29) via a plurality of rollers on separate routes and merge. Here, the dampening water (60) uses a water source roller (21) and a plurality of rollers from the watercraft (20) to prevent the ink (50) from reaching the non-image area of the plate surface (29). A uniform and thin water film is passed through the roller (2
A dampening solution (60) is applied to the entire surface of the plate (29) so that it can be formed on the surface of (2).

On the other hand, the ink (50) is used for the ink fountain (30).
By adjusting the gap formed by the doctor blade-like ink key (31) and the ink source roller (32) in the inside, a mechanism for adjusting the amount of the ink (50) transferred to the entire printing paper surface according to the pattern to be printed is provided. I have. In other words, the ink key (31) is
A large number of doctor blades divided at regular intervals in the roller axis direction are regularly arranged. Each time a picture to be printed is different, the gap between the ink source roller (32) and the ink key (31) can be arranged differently in the roller axis direction.

FIG. 3 schematically shows the above state. FIG. 3 shows an example in which the number of ink keys is divided into four (in an actual offset printing press, the ink keys are composed of 20 to 30 divided ink keys). Ink (50) on the surface of the ink roller (1) in the case of printing a pattern such that the largest number of images are printed, and the number of images is reduced to positions B (B), C (C), and D (D). The state such as the film thickness is shown. As shown in FIG. 1 again, the ink (50) is applied to the inking rollers (23, 2) for applying the ink (50) to the plate surface (29).
4, 25, 26), the applied amount of the ink (50), that is, the ink film thickness can be partially adjusted according to the number of the ink keys (31) and the axial width of the ink keys (31). On the other hand, the dampening solution (60) has a constant water film thickness on the plate surface (29) in the width direction of each roller.

In actual printing, since the ink (50) itself absorbs the dampening solution (60), the ink forming roller (2) is used.
3, 24, 25, 26), the thicker the ink film thickness is, the more the dampening water (60) is absorbed. Therefore, as described above, the ink film thickness varies in the width direction of the ink roller according to the picture. On the other hand, since the dampening solution (60) has a constant water film thickness, the portion A (A) shown in FIG. 3 absorbs a large amount of the dampening solution (60) and the portion D shows a small amount of absorption. Therefore, in a large amount of printing, the dampening solution (60) cannot be completely absorbed at the position D (D), so that there is a surplus. This is an example of an excess of dampening water (60), which causes various troubles as described above.

To prove this, the dampening solution (60) as shown in FIG. 3 is constant in the width direction of the ink roller (1), and the film thickness of the ink (50) is large at the position A (A). A continuous printing experiment was performed under the condition that the position B (B), the position C (C), and the position D (D) become thinner. The result is shown in FIG.
3 shows changes in the reflection density of each part with respect to the elapsed time of continuous printing.

From this result, at the position D (D) where the ink film thickness is the smallest, the excess of the dampening water (60) increases with time, the print density decreases (the ink transfer amount decreases), and the position C decreases. The portion (C) becomes smaller in the order of the portion B (B), and there is almost no change at the portion A (A). That is, while the excess of the dampening water (60) increases with time in the part D, the part A (A) is in a normal state and the ink amount and the dampening water are well balanced. become. If this state continues, the above-mentioned trouble will appear.

As means for solving such a problem, Japanese Patent Application Laid-Open No. 1-163066 discloses a method. According to this proposal, the dampening water droplets are extracted from the ink layer adhering to the surface of the roller by agglomeration due to electrostatic induction when a DC high voltage electric field is formed between the roller and the roller. An apparatus for removing excess dampening water of a printing press, comprising a high-voltage electrode for guiding downward, and the voltage electrode being disposed at a predetermined distance from the roller along the axial direction of the roller. However, by dispersing and emulsifying the fountain solution in the ink to a certain extent, an appropriate ink viscosity and its transferability can be maintained. However, it is not preferable to remove it, and it causes printing failure.

[0011]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems of the prior art, and an object of the present invention is to provide a dampening solution supply device for an offset printing press.
It is an object of the present invention to provide a dampening solution supply device including a dampening solution adjusting mechanism capable of partially adjusting a dampening solution supply amount according to an ink supply amount and maintaining an optimum emulsification balance.

[0012]

In order to achieve the above-mentioned object, according to the first aspect of the present invention, there is provided an offset printing press comprising at least a watercraft, a water source roller, a water transfer roller and a watering roller. In the dampening water supply device, a dampening water adjusting mechanism having a means for blowing a plurality of dry air or humidifying air in a width direction of the water transfer roller and a suction means for exhausting the air is arranged. And a dampening water supply device characterized by the following.

Further, in the invention of claim 2, the means for blowing the plurality of dry air or humidified air is arranged at substantially the number of ink keys for adjusting the ink of the ink supply device and at positions substantially corresponding thereto. This is a dampening water supply device.

[0014]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a general example showing a side view of an ink supply device (500), an ink roller group (100), a dampening solution supply device (600), a plate cylinder (40) and the like of an offset printing press. Dampening water supply device (60
It is the figure which arranged the dampening water adjustment mechanism (10) in 0). FIG. 2 is an enlarged side view of the dampening water adjusting mechanism (10).

As shown in FIG. 1, the dampening water supply device (600) of the present invention comprises a dampening water adjusting mechanism (10) in the width direction of the water transfer roller (19) of the dampening water supply device (600). And a dampening water adjusting mechanism (10).
Is composed of an air blowing means (F) and an air suction means (K), as shown in FIG.

The air blowing means (F) of the dampening water adjusting mechanism (10) passes air supplied from a compressed air source through a supply air pipe (13) and passes through an air guide pipe (1).
It is distributed to the solenoid valve (17) via 1). The air supplied to the solenoid valve (17) is, if necessary,
Supply air jet (12) with opening and closing of solenoid valve (17)
After reaching, it is squirted into the outside air. With the jetted air, the dampening water on the rotating water transfer roller (19) is increased to suppress vaporization of the dampening water when the jetted air is humidified air, and when the jetted air is dry air. Will be reduced to promote vaporization of the dampening solution. Thus, as the air blowing means (F),
Water transfer roller (1
9) The amount of the above dampening water is adjusted.

As shown in FIG. 2, an air suction means (K) is provided in the vicinity of the air blowing means (F) so as to suck the jetted air and vaporized dampening water. The air is exhausted from the exhaust pipe (15) through the exhaust port (14) through the air guide pipe (11).

A pair of dampening water adjusting mechanisms (10) comprising the above air blowing means (F) and air suction means (K).
Are arranged in the width direction on the water transfer roller (19) in accordance with the number of the ink keys (31) shown in FIG. 1, and the dampening solution is arranged in accordance with the amount of ink by opening and closing the ink key (31). The amount can be adjusted.

The dampening water adjusting mechanism (10) can be controlled by manual operation. However, in order to effectively use the dampening water supply device (600) of the present invention, automatic operation by feedback control is required. Is more effective. This feedback control is based on information based on the density of the printed matter and the like, on the basis of the ink film thickness information on the ink roller group (100) shown in FIG. 1, and on the dampening solution film thickness information of the plate surface (29). There is a method based on the information on the opening degree of the ink key (31) or a method based on the water content information from the ink emulsification state on the swing roller (27) or the like.

[0020]

Next, the present invention will be described in detail with reference to examples. <Embodiment 1> As shown in FIG.
0) are arranged in the width direction of the water transfer roller (19) in the same number as the number of the ink keys (31), and the water content measurement for obtaining the water content information from the ink emulsified state on the swing roller (27) on the opposite side. The machine (80) is connected to a moisture meter (70) for obtaining dampening solution film thickness information on the plate (29).
Installed near.

As shown in FIG. 2, the dampening solution adjusting mechanism (10) includes a supply air pipe (1) for introducing compressed air.
3) As 1mm hollow pipe with 20mmφ and 4mm thickness
Was sealed at one end, and 5 kg / cm ² of dry air was introduced from the other end by a compressor.
This dry air is sent through an air guide pipe (11) to a solenoid valve (17) that controls the presence or absence of air ejection.
The air guide tube (11) uses a commercially available soft nylon tube (manufactured by SMC), and the solenoid valve (17) is B5112.
(Manufactured by CKD) was used. In the supply air outlet (12), two blocks were overlapped to form a slit-shaped gap of 0.5 mm to 1 mm, and the dry air was ejected from the gap. The air was exhausted using an air blower.

At this time, the amount of dry air jet is 0 to
Adjustable within the range of 3 liters / min.
It was manufactured to be adjustable in the range of 0 to 6 liters / minute.

Continuous printing was performed for 30 minutes using the dampening water supply device (600) equipped with the above dampening water adjusting mechanism (10). At this time, control of the dampening solution adjusting mechanism (10) is performed by three types of methods: manual control by hand, feedback control from the measurement of the water content, and feedback control from the measurement of the dampening solution film thickness of the plate (29). However, the feedback control from the moisture content measurement enables the most stable printing based on the speed and accuracy of the measurement and judgment, and the variation of the printing density at this time is, for example, ± 0. 05, which was very stable.

[0024]

As described above, the present invention has the following effects. That is, in a dampening water supply device of an offset printing machine including at least a watercraft, a water source roller, a water transfer roller and a watering roller, approximately the same number of dry air or humidified air as the ink key is blown in the width direction of the water transfer roller. The dampening water supply device is equipped with a dampening water adjustment mechanism equipped with a means and suction means for exhausting the air, so the dampening water supply amount can be partially adjusted according to the ink supply amount The optimum emulsification balance can be maintained, and stable printing without fountain solution trouble is enabled.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing an arrangement of ink rollers and the like and an arrangement of a dampening solution adjusting mechanism of an offset printing press according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram showing a side surface of a dampening solution adjusting mechanism according to the embodiment of the present invention.

FIG. 3 is a schematic diagram for a printing test according to the present invention.

FIG. 4 is a graph showing the results of a printing test according to the present invention.

[Explanation of symbols]

 1 Ink roller 10 Dampening water adjusting mechanism 11 Air guide pipe 12 Supply air jet 13 Supply air pipe 14 Exhaust port 15 Exhaust pipe 17 Solenoid valve 19 Water transfer roller 20 ‥‥ water boat 21 ‥‥ water source roller 22 ‥‥ watering roller 23 ‥‥ first inking roller 24 ‥‥ second inking roller 25 ‥‥ third inking roller 26 ‥‥ fourth ink Wear roller 27 Swing roller 29 Plate surface 30 Ink jar 31 Ink key 32 Ink source roller 40 Plate cylinder 42 Blanket cylinder 50 Ink 60 Water fountain 70 Water Total 80 ‥‥ Moisture content measuring machine 100 ‥‥ Ink roller group 500 ‥‥ Ink supply device 600 ‥‥ Dampening solution supply device A ‥‥ Position A section B ‥‥ Position B section C ‥‥ position C unit D ‥‥ position D unit F ‥‥ air blowing means K ‥‥ air suction means

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Tsutomu Kawakami 1-5-1, Taito, Taito-ku, Tokyo Toppan Printing Co., Ltd. (72) Tomoko Mita 1-1-5-1 Taito, Taito-ku, Tokyo Letterpress Inside Printing Co., Ltd. (72) Inventor Tohru Sudo 1-5-1, Taito, Taito-ku, Tokyo Letterpress Printing Co., Ltd. (72) Inventor Masaaki Wada 1-15-1 Taito, Taito-ku, Tokyo Letterpress printing Inside the corporation

Claims (2)

[Claims] In a dampening water supply device for an offset printing press comprising at least a watercraft, a water source roller, a water transfer roller and a watering roller, a plurality of dry air or humidified air is blown in a width direction of the water transfer roller. A dampening water supply device comprising a dampening water adjusting mechanism having means and suction means for exhausting the air. 2. A method according to claim 1, wherein said means for blowing said plurality of dry air or humidified air is arranged at a position substantially corresponding to an approximate number of ink keys for adjusting ink in said ink supply device. Dampening water supply device.