JPH0330948A - Damping water supply apparatus in offset press - Google Patents

Abstract

PURPOSE:To accurately control the concn. of a chemical agent due to replenishment by accurately controlling concn. in a proper volume or wt. ratio in the initial setting of the damping water in a control tank and accurately controlling the replenishing amount of water and that of the chemical agent corresponding to the amount of water by weighing corresponding to the consumption of damping water. CONSTITUTION:The amount of water in a control tank 2 at the point of time when the second water level sensor 5b is turned ON is a predetermined definite value and an etching solution 8 and isopropyl alcohol 9 are injected in the control tank 2 in definite amounts corresponding to set concns. by driving quantitative pumps 10, 11 for definite times t1, t2 by the times T1, T2 of a material replenishing control apparatus 12. After the control tank 2 is set to a definite concn., a pump 4 is driven to send damping water in a printing press 1. When the damping water 3 in the control tank 2 is consumed by the printing press 1 and the third water level sensor 5c of a water level meter 5 is turned OFF, a water supply solenoid valve 7 is opened by the material replenishing control apparatus 12 detecting the ON/OFF states of the respective sensors 5a-5e of the water level meter 5.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to an apparatus that always maintains the chemical concentration of dampening water used in an offset printing press at a constant level and supplies the dampening water to the offset printing press.

[Prior Art] Offset printing presses use dampening water that is applied to printing plates and affects the finish of printing.

This dampening solution is mixed with an etching solution that has an affinity for the non-image areas of the printing plate and makes it easy to apply water, and isopropyl alcohol (hereinafter abbreviated as IPA). Density control is important for print finish.

FIG. 2 shows an example of a conventional dampening water supply device.

In the printing machine (A), the dampening water (C) in the adjustment tank (B) is
Continuously supplied with water by pump (D), printing machine (A)
The dampening water (C) left after moistening the printing plate is returned to the adjustment tank (B), and the dampening water (C) is circulated.

The adjustment tank (B) is provided with a pH sensor (E), and the pH value of the dampening water (C) in the adjustment tank (B) is constantly measured by a pH meter (F).

The pH value of the pH measuring device (F) is the same as that of the etching liquid (G).
When the concentration is insufficient, operate the pump (H),
Etching liquid (G) is replenished to maintain the pH value at a required level.

The amount of dampening water (C) in the adjustment tank (B) is automatically kept constant by the float valve (I).

The replenishment amount of IPA (J) is determined by replacing a part of the dampening water (C) sent to the pump (D) and printing machine (A) with the IPA replenishing device (K).
The concentration of IPA is determined by sending it as a sample to Japan and measuring its IPA concentration.

The IPA replenishment device (K) replenishes the sampled dampening water (C).
) is electrically measured to detect the IPA concentration, and if the concentration is insufficient, IPA (J) is automatically replenished until the appropriate concentration is reached.

[Problem to be solved by the invention] The pH of the etching solution is controlled by the raw water (L) of the dampening solution (C).
) and are easily influenced by acid or alkaline materials used at the printing site, making it difficult to maintain the correct concentration of the etching solution.

Furthermore, recent etching solutions contain a water-soluble resin as a chemical that maintains water rising to the plate surface, and the concentration of such a resin agent cannot be controlled by the pH value.

In addition, due to changes in the water temperature in the adjustment tank (B), the specific gravity of the dampening water (C) changes significantly, and furthermore, the dampening water (C)
Since it circulates between the printing machine (A) and the adjustment tank (B),
Ink gets mixed into the dampening water (C), and this ink causes problems in the electric sensors for measuring specific gravity and surface tension, causing variations in IPA concentration.

[Means for Solving the Problems] According to the present invention, there is provided a means for supplying dampening water to the offset printing press by circulating dampening water stored in the adjustment tank between the offset printing machines, and a means for supplying the dampening water to the offset printing press; water level detection means for detecting the water level at a plurality of different heights, a metering pump that measures etching liquid and supplies it to the adjustment tank, and a metering pump that measures and supplies isopropyl alcohol (IPA) to the adjustment tank. and a water supply solenoid valve that is opened when water is supplied to the regulating tank;
A water amount measuring means for measuring the amount of water immersed in the adjustment tank via the water supply electromagnetic valve, and a metering pump and IPA for supplying etching liquid in response to detection of different water levels by the water level detecting means. and a material replenishment control means that controls the timing of each operation of the water supply solenoid valve, etc., and controls the amount of material refilled by both of the metering pumps according to the amount of water measured by the water amount measuring means. By providing this, the above problem is solved.

[Function] The chemical concentration in the dampening solution is controlled by the amount of replenishment water and the relative amount of replenishing chemicals, and in the case of volatile chemicals, a predetermined amount of the solution is added after preparing the dampening solution. The amount of dampening water consumed is detected and the interval is measured until just before the amount is replenished, and the amount that is volatilized and lacking in the remaining amount of dampening water is replenished. Therefore, the chemical concentration of the dampening water can be controlled with high precision.

[Example] FIG. 1 shows one embodiment of the invention.

In the printing machine (1), the dampening water (3) in the adjustment tank (2) is
As before, it is supplied cyclically by a pump (4).

The concentration of the drug in the dampening solution (3) is adjusted by dividing it into an initial preparation and an intermediate replenishment adjustment.

For example, during initial preparation, drain water with the drain pump (6) until the lowest water level sensor (5e) of the water level gauge (5) no longer detects water (hereinafter referred to as "water level sensor OFF").
After emptying the adjustment tank (2), open the water supply solenoid valve (7) until the second water level sensor (5b) from the top detects water (hereinafter referred to as "water level sensor ON"), and then empty the adjustment tank. (2) Supply water.

Since the amount of water in the adjustment tank (2) at the time when the second water level sensor (5b) is turned on is a predetermined constant value,
A certain amount of etching solution (8) and IP according to the set concentration
A (9) is the timer (T) of the material replenishment control device (12).
+) (T2) and metering pump (lO) and metering pump (11
) is driven for a certain period of time (t I) (t 2) to inject into the adjustment tank (2).

After the concentration in the adjustment tank (2) is set at a constant concentration in this way, the pump (4) is driven to send the dampening water (3) into the printing machine (1).

When the dampening water (3) in the adjustment tank (2) is consumed by the printing machine (1) and the third water level sensor (5c) of the water level gauge (5) turns OFF, each of the water level gauges (5) Sensors (5a) to (5
e) Material replenishment control device (
12) opens the water supply solenoid valve (7).

When replenishing the dampening water (3), the amount of replenishment water injected into the adjustment tank (2) from the water supply solenoid valve (7) is measured by a flow rate sensor (13) provided at the tip of the solenoid valve (7). The measured value is input to the material replenishment control device (12).

The material replenishment control device (12) converts the replenishment amount of the etching solution according to the amount of water newly replenished into the adjustment tank (2) into the driving time of the metering pump (10), and calculates the required driving time. (t3) is set in the timer (T,), and the metering pump (10) is driven for that time (t,).

In addition, with respect to IPA, the material replenishment control device (12) also controls the driving time (t4) of the metering pump (11) corresponding to the appropriate replenishment amount according to the refilled water amount using a timer (T).
4), and the metering pump (11
) to drive.

However, since IPA is volatile, the IPA concentration of the dampening solution (3) decreases over time after initial setting.

Therefore, in the material replenishment control device (12), the second sensor (5b) of the water level gauge (5) is ONL,
A metering pump that measures the time until the second sensor (5c) turns OFF with a timer (T,) and replenishes IPA according to the replenishment interval time (t,) measured by this timer (T5). Add a driving time corresponding to the shortfall due to volatilization to the driving time (t4) in (11).

The timer (T,) is reset every time IPA is refilled.

[Effects of the Invention] In the present invention, the initial setting of the dampening water in the adjustment tank is performed at an appropriate volume ratio or weight ratio to accurately adjust the concentration.
Thereafter, depending on the consumption of dampening water, the amount of water to be replenished and the amount of medicine to be replenished in accordance with the amount of water can be accurately measured and controlled, thereby accurately managing the concentration of medicines due to replenishment.

Furthermore, in the case of volatile IPA, the replenishment interval for each predetermined amount is measured, and the amount of IPA that is insufficient due to volatilization is measured.
Since the amount of volatile IPA is calculated and the shortage is added to the IPA content of the new replenisher, the concentration of volatile IPA can also be managed easily.
done accurately.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing one embodiment of the present invention, and FIG. 2 is a block diagram showing a conventional example. (1) Printing machine (2) Adjustment tank (3) Dampening water
(4) Pump (5) Water level gauge (5
a) ~ (5e) Water level sensor (6) Drain pump (
7) Solenoid valve for water supply (8) Etching liquid (9) IP
A (10) Metering pump (11) Metering pump (1
2) Material replenishment control device (13) Flow rate sensor (T□) ~
(T,) Timer Figure 1 Figure 2

Claims (2)

[Claims] (1) A means for supplying dampening water to the offset printing presses by circulating the dampening water stored in the adjustment tank between the offset printing machines, and detecting the water level in the adjustment tank at multiple different heights. water level detection means; a metering pump that measures and supplies etching solution to the adjustment tank; a metering pump that measures and supplies isopropyl alcohol (IPA) to the adjustment tank; and a metering pump that is opened when water is supplied to the adjustment tank. a water supply solenoid valve; a water amount measuring means for measuring the amount of water input into the regulating tank via the water supply solenoid valve; and in response to detection of different water levels by the water level detection means,
The timing of each operation of the metering pump that supplies the etching solution, the metering pump that supplies IPA, the water supply solenoid valve, etc. is controlled, and the amount of material supplied by both metering pumps is controlled according to the amount of water measured by the water metering means. A dampening water supply device for an offset printing press, comprising: material replenishment control means for controlling the amount of replenishment. (2) The material replenishment control means detects the dampening water replenishment interval based on the operating time interval of each water level of the water level detection means, and detects the insufficient amount of dampening water due to volatilization of IPA in the remaining dampening water at the time interval. 2. The dampening water supply device for an offset printing press according to claim 1, wherein when replenishing IPA after a certain time, the dampening water supply device for an offset printing press is added to an appropriate amount of replenishment water.