JPH0257036B2 - - 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 excessive additives are consumed.
This has resulted in disadvantages such as being uneconomical.

[Summary of the invention]

The purpose of the present invention is to fundamentally solve such drawbacks of the conventional method, and in addition to inserting a hydrometer into the feed water mixed with additives, a drive section for driving the actuator of the switch is attached to the head of the hydrometer. The switch is operated by the rising and falling movement of the hydrometer, and the electric valve is driven by a control circuit that responds to the output of the switch.
The present invention provides an extremely effective additive concentration control device for water supply for printing, in which the concentration of additives added is controlled by this electric valve.

〔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 weight adjustment pot V,
Alcohol supplied from the alcohol tank 7 in accordance with 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 increases, the sinking will occur. Therefore, for the purpose of detecting this up-and-down movement, a switch SW such as a micro switch equipped with an actuator ACT is provided. The actuator
The distance between the ACT and the tip of the head of the hydrometer 10 is adjustable.

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 showing the switch SW and the head of the hydrometer 10. The actuator ACT, which extends above the head of the hydrometer 10, is rod-shaped and corresponds to the actuator ACT. The actuator
Vertical cut groove 21 that fits with the tip of ACT
A driving part 23 having a projecting piece 22 with a flat and flat cross section formed from above is attached to the tip of the head of the hydrometer 10, and the lower part of the driving part 23 facilitates attachment to the tip of the head. Therefore, the cylinder 24 has an open bottom surface, and is made of an elastic material such as rubber in order to be compatible with the hydrometer 10 made of glass.

Further, the projecting piece 22 is fitted into the distal end of the arm 25 extending from the support 11 so as to be freely downwardly inserted into a gap between mutually parallel guides 26 and 27 which are formed to project horizontally and at right angles to the actuator ACT. This prevents the hydrometer 10 from rotating in the horizontal direction, and the tip of the actuator ACT and the notch 21
The two are always in a state of play.

Therefore, when the hydrometer 10 floats, the actuator ACT is driven upward by the bottom 21a of the cut groove 21, and the lever action of this causes the switch SW to operate with a slight levitation force, causing the hydrometer to float. 10
Detection is made that the object has surfaced.

In addition, by attaching the driving part 23 to the hydrometer 10, the air chamber volume of the hydrometer 10 becomes large depending on the superposition of these parts, and the hydrometer 10 becomes large and the same specific gravity Since the width of the up-and-down movement in response to a change is large, the up-and-down movement width is approximately 2 mm for a 1% change in the concentration of alcohol, improving detection accuracy.

Figure 3 is a circuit diagram of the control circuit.
When the SW detects the floating of the hydrometer 10 and turns on, power supplies e ₁ and e ₂ are applied to the solenoid valve SV, which is driven to an open state and starts supplying alcohol.

At the same time, relay R1 operates and
The contact _R11 performs self-holding and bypasses the switch SW, while the contact R12 starts the timer T1.

Therefore, due to the sinking of the hydrometer 10, the switch
Even if SW is turned off, solenoid valve SV, relay R1
and timer T1 continues to operate.

After a certain period of time, timer T1 times up,
When contact T1 ₁ is turned off, relay R1 is restored,
In response to this, the solenoid valve SW is also restored and the supply of alcohol is stopped, and the timer T1 is also restored, but at the same time as the contact T1 ₁ is turned off, the contacts T1 ₂ are turned on, the timer T2 is activated, and the contact T2 ₁
is turned off, so even if the switch SW is on, the solenoid valve SV, relay R1, and timer T1 are forced into the recovery state.

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 switch SW 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, switch SW and actuator ACT
may operate in accordance with the ups and downs of the hydrometer 10, and may be constructed integrally with a spring, contacts, etc., and the material and shape of the drive section 23 may be determined accordingly.

Furthermore, the control circuit can be configured using semiconductor elements instead of relays, and instead of the solenoid valve SV, a motor valve or the like may be used as an electric valve. Substitute liquids, etching liquids, etc. can be selected arbitrarily depending on the situation, 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 block diagram showing the water supply system of a printing press, Fig. 2 is an enlarged perspective view of the head of the switch and hydrometer, and Fig. 3 is a circuit diagram of the control circuit. be. 1... Water tank, 2... Water supply, 5... Detection tank, 7...
... Alcohol tank, 9 ... Guide, 10 ... Hydrometer, 23 ... Drive unit, ACT ... Actuator,
SW...Switch, SV...Solenoid valve (motorized valve), R
1...Relay, T1, T2...Timer.

Claims (1)

[Claims] 1. A hydrometer that is freely floatable and sinkable into printing water supply mixed with additives, a switch equipped with an actuator that detects the floating motion of the hydrometer, and the actuator provided at the head of the hydrometer. The invention is characterized by comprising: a drive unit that drives the switch to operate the switch; a control circuit that responds to the output of the switch; and an electric valve that is driven by the control circuit and controls the concentration of the additive. Additive concentration control device for printing water supply.