JPS63295260A - Damping water supplying device - Google Patents

Abstract

PURPOSE:To ensure that the composition of damping water is constant for each printing press, printing quality is stable and use of surplus additives can be obviated, by formulating damping water in a concentrated manner and supplying it to each printing press where a plurality of printing presses are arranged. CONSTITUTION:A supplying tank 20 is disposed in succession to a formulating tank 10. A water feed pipe 43 for pouring water (industrial water) into the formulating tank 10, an IPA feed pipe 44 for feeding IPA and an etching liquid feed pipe 31 for pouring an etching liquid into the tank 10 are extended to the tank 10. The formulating tank 10 is equipped with a stirrer 11 rotated by a motor 12 for stirring and mixing the liquids poured into the tank 10, a liquid level sensor 13 and a pH sensor 14. The capacity of the formulating tank 10 is, for example, 500 l, whereas the capacity of the supplying tank 20 is 1500 l, the capacities being set to be sufficient for use for dampening arrangements of a multiplicity of printing presses. The liquid level sensor 13 is so set that it can detect three liquid levels, i.e., low (L), medium (M) and high (H) levels, whereas s liquid level sensor 21 is so set that it can detect a high (H) level.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a dampening water supply device for preparing dampening water used in lithographic printing and supplying the dampening water to a printing unit of a printing press.

[Prior art]

In planographic printing represented by offset sheet-fed printing presses and offset rotary printing presses, oleophilic image areas and hydrophilic non-image areas are formed on the printing plate surface, and ink and dampening water are applied to this plate surface. By supplying ink, ink is deposited only on the image area, and printing is performed by transferring the ink to the printing paper.

Generally, the dampening water supplied to the printing plate surface is not just water (a liquid made by mixing water with various additives is used for the purpose of improving printing performance.Additives include gum arabic liquid, Etch liquid consisting of surfactants, phosphoric acid, ammonium phosphate, etc., Improv alcohol (hereinafter referred to as I)
PA) etc. are known.

Conventionally, dampening water as described above is prepared by mixing water and additives such as IPA and etch liquid in a dampening water tank provided for each printing machine, and then using a supply pump to supply the dampening solution to the printing unit. It was what was being supplied to the water system.

[Problem that the invention seeks to solve]

According to such conventional technology, dampening water is mixed for each printing machine, so the amount of additives varies from printing machine to printing machine, resulting in unstable printing quality and the possibility of adding more than necessary. If additives are mixed in, it means that unnecessary additives are mixed in. and.

When adding IPA, it is necessary to comply with the Organic Solvent Prevention Regulations (alcohol concentration 5%) of the Labor Standards Act.
If the blending amount was controlled for each printing machine, it would be difficult to maintain this value, including the relationship with the surfactant. moreover,
Providing a dampening water preparation and supply device for each printing machine has the disadvantage of being structurally complex and expensive.

[Means for solving problems]

The present invention, which was made to solve the above-mentioned problems, mixes water and additives to form dampening water for lithographic printing, and uses a dampening water supply device for supplying this dampening water to a printing press. , a mixing tank into which water and additives are injected and mixing them to prepare dampening water to be supplied to a plurality of printing machines; and a mixing tank is provided following this mixing tank.

A supply tank that stores the blended dampening water and supplies the dampening water to each printing machine, an injection amount detection sensor installed in the blending tank, and a signal from the detection sensor that controls the amount of liquid in the blending tank. A dampening water supply characterized by having an injection amount control means for injecting water into a mixing tank when the amount is below a certain value, and injecting a predetermined amount of additive when the water reaches a predetermined liquid amount. It is a device.

[Effect]

The present invention is applicable to cases where multiple printing machines are installed.
Because dampening water is prepared centrally and supplied to each printing machine, the composition of the dampening water is constant for each printing machine, stabilizing print quality and eliminating the need for extra additives. .

Moreover, the mixing of dampening water in the mixing tank is controlled based on the signal from the injection amount detection sensor, so water and additives are always mixed at a constant ratio, and the dampening water is continuously supplied to the mixing tank. Set up a tank.

Since the blended dampening water is stored, dampening water can be stably supplied to each printing machine.

〔Example〕

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be explained in detail below based on an embodiment shown in the drawings.

FIG. 1 is an explanatory diagram of a dampening water supply device according to the present invention. In the figure, reference numeral 10 is a mixing tank, and a supply tank 20 is installed following this mixing tank 10.

The mixing tank 10 includes a water transfer pipe 43 for injecting water (industrial water) into the mixing tank, and an iPA transfer pipe 44 for transferring IPA. and an etchant transfer pipe 3 for injecting the etchant
1 is connected to the water transfer pipe 43 and the IPA transfer pump 42 .1 to the fPA transfer pipe 44 to control the injection amount. For the etchant transfer pipe 31, an etchant transfer pump 32 is provided.

In addition, the mixed liquid injected into the mixing tank 10 is stirred.

A stirrer 11 rotated by a motor 12 for mixing. A liquid level sensor 13 and a pH sensor 14 are provided.

Further, the supply tank 20 is provided with a liquid level sensor 21, and a dampening water transfer pipe 16 is provided with a supply pump 15 for transferring dampening water from the mixing tank 1o to the supply tank 2o. A transfer pipe 22 for supplying dampening water to a dampening water device of each printing machine (not shown) is installed.

Here, the capacity of the mixing tank 1o is, for example, 5oool, and the capacity of the supply tank 20 is 15001, which is enough to accommodate the dampening water devices of many printing machines.

Further, as for the IPA transfer pump 42° supply pump 15, which has a large transfer amount, a magnetic coupling type centrifugal pump, for example, can be used.

Etch liquid transfer pump 52 whose transfer amount is small and requires fine adjustment
For example, a diaphragm metering pump can be used.

Further, as the liquid level sensor 13.21 provided in the mixing tank 10 and the supply tank 2o, a normal polarized liquid level sensor can be used. ), high (H), low (L) is the level corresponding to almost zero liquid level, and medium (M) is the level when water is poured during mixing. The level corresponding to the amount of IPA is set so that high (I()) can detect the level corresponding to the amount of IPA injected after the water injection is completed. It is possible to use a type in which a DC amplifier with a large input resistance measures the electrode potential difference such that a high (H) level indicating a state of almost full filling can be detected.

The pH value from the pH sensor 14 is also set to be able to detect two levels: low (L), which corresponds to the target value, and high (H), which is about 2 pH values larger than the target value.

Liquid level sensor 1, 1, 21, peno-sensor 14 as described above. Each transfer pump 15, 52.42, solenoid valve 4
1. The agitator motor 12 is electrically connected to a control circuit 50, and the control circuit 50 controls operations such as dispensing dampening water based on signals from each sensor.

Although the electric circuit configuration of the control circuit 50 is not limited in any way, it can be controlled by a microcomputer, for example, and in this case, it can be configured with a ROM storing a control program and fixed data, a data storage RAM, a CPU, and the like.

Next, the operation of the dampening water supply device having the above structure will be explained based on FIGS. 2 to 4. This operation is controlled by the control circuit 5o as described above.

As shown in FIGS. 2 and 3, the liquid level in the mixing tank 1° is below low (L), which is a state where the liquid amount is almost zero, and the liquid level in the supply tank 20 is not full. (high(
H) or below), the solenoid valve 41 opens and water is injected into the mixing tank 10. When a predetermined amount of water is injected and the liquid level in the mixing tank 1o reaches medium (M), the solenoid valve 41 closes to stop the water injection, and the IPA transfer pump 42 is first activated.

IPA is injected into the mixing tank 10. When the liquid level in the mixing tank reaches high (H) due to the injection of IPA, the operation of the pump 42 is stopped and the injection of IPA is completed.

As a result, IPA is injected into the water, and as described above, it is possible to set the IPA concentration to a predetermined value of 5% or less.

Next, the H liquid injection pump 52 is activated and the H liquid mixing tank 10 is
When the injection into the mixing tank is started, the stirrer 11 is operated to stir the combined liquid in the mixing tank to completely mix it. The injection amount of the etchant is controlled by the pH value.

As shown in Figure 4, the pH value has two levels: low (L), which is the target value, and high (H), which is set slightly higher than this target value, and the pH value is The pH value detected by -14 is high (H
) or above, continuously inject the etchant and adjust the temperature from low (L) to high (H).
), the etchant is intermittently injected, and when the Peno value reaches the target value low (L), the etchant injection is stopped. Thereafter, the pH value is checked again after a certain period of time (for example, 5 minutes), and if the target pH value has not been reached, the above-described etchant injection operation is performed again.

Generally, the pH value of dampening solution due to etchant contamination is 5.
It is said that a pH value of 5 to 6.5 is desirable, and a dampening solution having a desirable pH value can be prepared by the above operation.

The dampening water prepared in this way is transferred from the mixing tank 10 to the supply tank 20 by operating the supply pump 15 after confirming that the liquid level in the supply tank 2° is below high (H), While the supply tank 20 is not full, the dampening water mixing operation in the mixing tank 10 is performed.

The supply tank 20 is piped to each printing machine.

When each printing machine needs to be replenished with dampening water, the dampening water is transferred from the supply tank 20 to each printing machine.

The above explanation is based on one embodiment of the dampening water supply device of the present invention, and the present invention is not limited to this embodiment in any way. That is, the order of injection of IPA and water into the mixing tank can be reversed, and the case where mixing of IPA is unnecessary can be handled by deleting the configuration from the above embodiment related to IPA.

Further, the etchant injection operation does not necessarily need to be divided into two injection operations, and it is also possible to handle only continuous injection.

〔effect〕

According to the present invention as described above, water and additives are injected and mixed based on a signal from an injection amount detection sensor using a combination of a liquid level sensor and a pH sensor. In addition, we installed a supply tank following the mixing tank, stored a large amount of dampening water in the supply tank, and distributed it to each printing machine. There is no variation in the composition of the dampening water, and printing quality is stabilized. At the same time, the amount of additives used can be reduced because there is no need to mix in excess additives.

[Brief explanation of drawings]

Fig. 1 is an explanatory diagram of the dampening water supply device of the present invention, Fig. 2 is a flow chart of dampening solution preparation and supply controlled by a control circuit, and Figs. 6 and 4 are explanatory diagrams of dampening solution preparation. It is. 10...Mixing tank 20...Supply tank 15.21...Liquid level sensor 14...Phase sensor 50...Control circuit

Claims (1)

[Claims] 1) Mix water and additives to make dampening water for lithographic printing,
In the dampening water supply device that supplies this dampening water to printing machines, water and additives are injected, and there is a mixing tank that mixes them to prepare dampening water to be supplied to multiple printing machines, and a mixing tank that mixes them to prepare dampening water to be supplied to multiple printing machines. A supply tank that is connected to the tank and stores the blended dampening water and supplies the dampening water to each printing machine, an injection amount detection sensor that is installed in the mixing tank, and a signal from this detection sensor. and an injection amount control means for injecting water into the mixing tank when the liquid level in the mixing tank becomes below a certain value in response to the above, and injecting a predetermined amount of additive when the predetermined liquid level is reached. dampening water supply device.