JPH038276B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to an apparatus for automatically controlling the concentration of additives mixed into water supply for printing.

[Prior art]

In general, printing plates are supplied with ink and moisture during printing.
Particularly in offset printing, additives such as alcohol are mixed into the water supply for the purpose of lowering the surface tension of the water supply and reducing staining of the plate.

However, the mixing status of additives is adjusted empirically, and it is difficult to maintain the mixing concentration at the optimum value, and there are disadvantages such as excessive additive consumption and uneconomical effects. ing.

[Summary of the invention]

The purpose of the present invention is to fundamentally solve the above-mentioned drawbacks of the conventional methods, and in addition to inserting a hydrometer into feed water mixed with additives, a means for driving a detection switch is provided at the head of the hydrometer, and the hydrometer is A detection switch is actuated by the up-and-down motion of the sensor, and a control circuit that responds to the output of the detection switch drives an electric valve, and this electric valve controls the concentration of the additive. The present invention provides an additive concentration control device for printing water supply.

〔Example〕

Hereinafter, details of the present invention will be explained with reference to figures showing examples.

FIG. 1 is a block diagram showing the water supply system of a printing press. In order to keep printing conditions constant, water supply 2 in a water tank 1 maintained at a predetermined temperature is supplied to a water tank 4 and a water tank 1 by a pump P and a water supply pipe 3. Water is supplied to the detection tank 5, and in the water tank 4, a water supply roller (not shown) supplies moisture to the plate cylinder on which the plate is mounted, and excess water is returned to the water tank 1 via the drain pipe 6. In the detection tank 5, for the water supply 2 supplied through the water volume adjustment pot V,
Alcohol supplied from the alcohol tank 7 in response to the opening of the solenoid valve SV is mixed in, and when the water level reaches a certain level or higher, it is discharged to the water tank 1 via the drain pipe 8.

In addition, a hydrometer 10 is placed in the water supply 2 of the detection tank 5, and is supported by a guide 9 fixed to a drain pipe 8 so as to be able to float and sink. As the amount of water increases, it will sink, so a proximity switch PXS is provided for the purpose of detecting this floating motion.
The adjusting screw 13
The distance between the proximity switch PXS and the tip of the head of the hydrometer 10 can be adjusted freely.

Note that the pointer 14 is fixed to the support 11 and the scale plate 15 is fixed to the arm 12 correspondingly.
This allows the mixing degree of alcohol and water to be expressed as a 100-part ratio.

FIG. 2 is an enlarged perspective view of the proximity switch PXS and the head of the hydrometer 10. A circular metal plate 21 for driving the proximity switch PXS is fixed to the tip of the head of the hydrometer 10. , the approach of the metal plate 21 as the hydrometer 10 rises is controlled by a proximity switch.
PXS is designed to detect and operate.

FIG. 3 is an enlarged perspective view of the head of the hydrometer 10 showing another embodiment, in which a sleeve 22 is fixed to the lower surface of the circular metal plate 21 and the sleeve 22 is attached to the tip of the head of the hydrometer 10. This is suitable when the head of the hydrometer 10 has a small diameter.

In addition, by fixing the metal plate 21 to the hydrometer 10, the air chamber volume of the hydrometer 10 becomes large, and the hydrometer 10 becomes large.
Since the width of the floating motion for the same change in specific gravity is large, the width of the floating motion is approximately 2 mm for a 1% change in the concentration of alcohol, improving detection accuracy.

Figure 4 is a circuit diagram of the control circuit.
When the proximity switch PXS, which is activated by E ₁ and E ₂ , detects the metal plate 21 and is activated, the internal contact of the switch PXS is turned on, and the relay R is activated.
1 operates, contact R1 ₁ is turned on, and AC power supply e ₁ ,
Apply e ₂ to relay R2 and timer T1.

Then, relay R2 operates and contacts R2 ₁
Since the relay R2 is self-retaining, even if the proximity switch PXS is restored due to sinking of the hydrometer 10, the relay R2 is
and timer T1 continues to operate, contact R2 ₂
The solenoid valve SV is driven and opened to start supplying alcohol.

After a certain period of time, timer T1 times up,
When contact T1 ₁ is turned off, relay R2 is restored,
Correspondingly, the solenoid valve SV is also restored, so the supply of alcohol is stopped and contact T1 ₂
When turned on, the timer T2 is energized and the contact T2 ₁
OFF, the relay R1 is forcibly restored regardless of the output of the proximity switch PXS, and the timer T1 is restored.

When contact _T12 is turned off due to recovery of timer T1, power to timer T2 is cut off, but timer T2 has an integrating circuit or a capacitor, and continues to operate for a predetermined time even after power is cut off. Therefore, during a predetermined period of time after the alcohol supply is stopped, the detection of the hydrometer 10 by the proximity switch PXS is disabled, the unstable floating motion of the hydrometer 10 is ignored, and the control state becomes stable.

In addition, the amount of alcohol supplied at one time is determined by the timer T.
1, and the mixing situation is determined by the degree of opening of the pot V.

Therefore, if the concentration of alcohol mixed in the feed water 2 circulating between the water tank 1 and the detection tank 5 decreases, alcohol is automatically supplied, and once the alcohol is supplied, the hydrometer 10 floats and sinks. Even if there is movement, it is ignored until a predetermined time has elapsed, and the concentration of alcohol mixed in the water supply 2 is stably and accurately maintained within a predetermined range, and the printing situation is always maintained in a suitable state.

Further, the concentration of alcohol mixed in is indicated by the pointer 14 and the scale plate 15, and can be finely adjusted using the adjustment screw 13 based on the pointer 14, so that setting of the mixed concentration becomes easy and accurate.

However, instead of the proximity switch PXS, a photoelectric switch, an electromagnetic switch, etc. may be used as a detection switch, and correspondingly, a corresponding driving means may be used instead of the metal plate 21, and the control circuit does not rely on relays. The same effect can be achieved even if the structure is made of a semiconductor element, and instead of the solenoid valve SV, a motor valve or the like may be used as an electric valve, and the additive may be not only alcohol, but also an alcohol substitute or etching liquid, etc., depending on the situation. The selection is arbitrary and various modifications are possible.

〔Effect of the invention〕

As is clear from the above description, according to the present invention, with a simple configuration, the additive concentration of printing water supply water is stably and accurately maintained within a predetermined range, and the printing condition is always maintained in an appropriate state. Excess consumption of additives is prevented, cost savings are achieved, and significant effects are achieved in controlling additive concentrations in various printing water supplies.

[Brief explanation of the drawing]

The figures show an embodiment of the present invention, Fig. 1 is a configuration diagram showing a printing material water supply device, Fig. 2 is an enlarged perspective view of a proximity switch and the head of a hydrometer, and Fig. 3 is another embodiment. FIG. 4 is an enlarged perspective view of the head of the hydrometer, and FIG. 4 is a circuit diagram of the control circuit. 1...Water tank, 2...Water supply, 5...Detection tank, 7...
... Alcohol tank, 9 ... Guide, 10 ... Hydrometer, 21 ... Metal disk (driving means), PXS ... Proximity switch (detection switch), SV ... Solenoid valve (motorized valve), R1, R2 ... ...Relay, T1, T2...
timer.

Claims (1)

[Claims] 1. Activating a hydrometer that is freely floatable and sinkable into printing water supply mixed with additives, a detection switch that detects floating and sinking movements of the hydrometer, and a detection switch provided at the head of the hydrometer. an additive concentration in water for printing, comprising a driving means for controlling the concentration of the additive, a control circuit that responds to the output of the detection switch, and an electric valve that is driven by the control circuit and controls the concentration of the additive mixed in. Control device.