JPH07117512B2 - Concentration measuring device for mixed solution - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to the concentration of alcohol in an aqueous alcohol solution,
The present invention relates to an apparatus for detecting the component concentration of a mixed solution, and more particularly to an apparatus for measuring the concentration of a mixed solution suitable for detecting and controlling the alcohol concentration in dampening water in offset printing.

[Background of the Invention]

As is well known, it is necessary to apply dampening water to the plate surface in offset printing. As a device for supplying the dampening water to the plate surface, that is, a dampening water device, a so-called Molton system using a molton (water-holding cloth) as a watering roller for the plate surface has been widely used. It was

However, in recent years, the so-called alcohol dampening system, which does not use a Molton roller to supply water to the printing plate, is an alternative to the Molton method described above because it is easy to maintain stable image quality and is easy to operate and maintain. It has become widespread.

FIG. 9 shows an example of this alcohol dampening system. In this figure, 1 is a dampening water tank, which is generally equipped with a constant temperature device and keeps the dampening water inside at a temperature of about 15 ° C. It is becoming like this. The dampening water in the tank 1 is pumped up by the pump 2 and sent to the water boat 3 of the printing machine. In the water boat 3, a part of the roller group 4 of the dampening water device is provided. It is soaked in dampening water. Then, the dampening water in the water boat 3 is taken out by the roller group 4 and supplied to the surface of the plate 6 wound around the plate cylinder 5.

On the other hand, the dampening water excessively supplied into the water boat 3 is returned to the dampening water tank 1 via the return pipe 7.

By the way, in this alcohol dampening system,
Since the roller for watering the plate surface itself does not have strong water retention like the Molton roller, in order to supply sufficient dampening water to the plate surface, a surfactant such as alcohol is added to the dampening water, It is said that it is necessary to reduce the surface tension so that water can be easily dispersed in the ink.

Here, the most commonly used surfactant is isopropyl alcohol among alcohols, and the alcohol concentration in the dampening water at this time is usually 5% to 20%. To a small extent, this change in alcohol concentration has a very large influence on the amount of water supplied to the inking device, that is, the amount of water supplied to the plate surface, and further on the quality of the printed matter.

Therefore, in such an alcohol dampening system, maintaining the alcohol concentration in the dampening water at a predetermined value is an indispensable element, and for this purpose, it is necessary to measure the alcohol concentration.

However, as such a method for measuring the alcohol concentration, conventionally, the fact that the specific gravity of alcohol is smaller than water is used, a specific gravity bottle is used to measure the specific gravity of dampening water, and a method for determining the alcohol concentration is mainly used. Was used.

In the alcohol dampening system described above, the dampening water is usually pumped to the water boat on the printing press.
Since the dampening water is circulated between the tanks, there are many fine bubbles in the dampening water, which adhere to the specific gravity bottle, making accurate concentration measurement difficult. Further, the adhesion of ink or dirt in the dampening water to the specific gravity bottle also causes a measurement error and necessitates frequent cleaning, which makes the handling complicated.

Further, even in general mixed solutions other than the above-mentioned dampening water, in the method of directly inserting the sensor into the solution to measure the concentration, the detected value is inaccurate due to the dirt of the sensor, and when changing the type of the solution. Since it is necessary to clean the sensor each time, the handling is inconvenient and improvement is strongly desired.

[Object of the Invention]

The present invention has been made under the background described above, and its purpose is to continuously and continuously with high accuracy, without being affected by the concentration of each component in the mixed solution due to dirt or the like mixed in the solution. An object of the present invention is to provide a device for measuring the concentration of a mixed solution which can be measured and is easy to handle.

[Outline of Invention]

In order to achieve this object, the present invention detects the gas concentration of each component in a predetermined space partitioned in contact with the liquid surface of the mixed solution, the concentration of each component of the mixed solution based on this gas concentration. In the measuring device, a flow of the outside air continuously flowing in the above-mentioned predetermined space is made, and the above-mentioned gas concentration is detected in the flow of the outside air. Therefore, the mixed solution Is supplied to the measuring unit consisting of a predetermined container, a return pipe installed in the measuring unit for keeping the liquid level of the mixed solution in the container at a constant height, and the liquid level of the mixed solution from above. A trough-shaped member installed so as to cover the predetermined space, a gas circulation means for circulating the outside air in the space partitioned by the trough-shaped member, and an outside air from the inside of the space. Gas detection means installed in the passage on the discharge side The provided continuously and said point so as to detect the component concentration of the mixed solution on the basis of the detection result of the gas sensing means.

Example of Invention

Hereinafter, the concentration control apparatus for a mixed solution according to the present invention will be described in detail with reference to the illustrated embodiments.

FIG. 2 shows an embodiment of the present invention applied to an alcohol dampening system of an offset printing machine. Reference numeral 8 denotes a detecting portion of this apparatus, which is a dampening water sent from the pump 2 toward the water boat 3. Part of the water is collected through the bypass pipe 9, and after measurement, is returned to the dampening water tank 1 through the pipe 10.

The mixed solution used in the description of this embodiment is the dampening water (alcohol / water mixed solution) described above, but it goes without saying that it can be applied to other mixed solutions.

A control unit 11 calculates the alcohol concentration in the dampening water based on the alcohol gas concentration detection signal from the detection unit 8 and outputs a control signal so that the concentration is preset by a digital switch or the like. That is, when the alcohol concentration becomes lower than the set value, the solenoid valve 12
To supply a predetermined amount of alcohol into the dampening water tank 1.

Reference numeral 13 denotes a display unit, which digitally displays the measured alcohol concentration, and which the printing machine operator appropriately controls.

FIG. 1 is an enlarged cross-sectional view of the measuring unit 8. When the dampening water collected through the bypass pipe 9 enters the measuring unit 8, it is a shield plate.
Go under 14 The shielding plate 14 functions to prevent waves from being generated on the water surface in the measuring section 8.

The return pipe 10 has a shape in which the upper end of the return pipe 10 projects upward in the measuring section 8 to keep the height of the water surface in the measuring section 8 constant and dampen the excess dampening water. It works to return to the water tank 1.

Reference numeral 16 is a lid of the measuring unit 8, to which a temperature sensor 17, a gas sensor 18, and a gutter-shaped portion 19 are attached.

The trough-like portion 19 is for partitioning the liquid surface of the dampening water 21 to form a predetermined closed space 20 as shown in FIGS. 3 (a) and 3 (b), and the sensor 18 is It functions to detect the concentration of the alcohol gas that has been vaporized from the dampening water 21 that has been drawn into the measuring unit 8 and that has filled the sealed space 20.

In this closed space 20, by constantly operating the metering air pump 22, fresh air that does not contain alcohol gas sucked from the outside through the pipe 23 is circulated. The portion 19 of the so that the air passing therethrough comes close enough to the surface of the dampening water 21 and acts as a guide for flowing in contact with it along the surface, and as a result, this gutter-shaped portion The air passing through 19 is made into a state containing alcohol gas which is sufficiently dampened and evaporated from water 21 in a short time.

Then, while passing through the gutter-shaped portion 19 in this manner,
The concentration of alcohol gas in the air containing alcohol gas vaporized from the surface of the dampening water is measured by the sensor 18 in the measuring chamber 24.
Is being measured by

At this time, the flow rate of air by the pump 22 is
It is necessary to set the time so small that the same air stays in the measuring chamber 24 for a sufficient time necessary for detecting the alcohol concentration from the air in the chamber 24.

Further, the size of the trough-shaped portion 19 is long enough so that the air passing through the trough-shaped portion 19 is sufficiently filled with alcohol gas in accordance with the suction amount of the air pump 22. In order to be detected by the sensor 18, it is necessary to make the length as short as possible, and accordingly, it is necessary to determine the predetermined dimensions in consideration of these.

The sensor 18 is a well-known catalytic combustion type gas sensor as shown in FIG. 4, which comprises a measuring element 18a and a dummy 18b as shown in FIG. 5, and a detection signal is obtained by a bridge circuit. The sensor used in the present invention is not limited to such a catalytic combustion type, but may be any sensor as long as it exhibits the detection characteristics required for a predetermined gas, for example, a semiconductor type sensor, an infrared ray sensor. Any sensor such as an absorption type sensor, a heat conduction type sensor, or a light wave interferometer sensor may be used. The gutter-shaped portion 19 is easily detachable, and can be easily cleaned or replaced when there is a risk of being affected by dirt or the like.

FIG. 6 shows a schematic flow of the operation of the entire apparatus. Hereinafter, each step will be described.

Measurement of Step 1 (S-1) gas concentration With the sensor, the concentration of alcohol gas vaporized from the dampening water surface, which is included while the fresh air is sucked in from the outside by the air pump 22 and passes through the trough-shaped portion 19, taking measurement.

Step 2 (S-2) Measurement of liquid temperature The temperature of the liquid is measured by the temperature sensor 17 mounted in the dampening water tank 1.

Step 3 (S-3) Calculation of alcohol concentration in dampening water In this step, the alcohol concentration in dampening water is read as follows by the gas sensor output value and the liquid temperature value captured in Steps 1 and 2. calculate.

Since the liquid temperature T and the gas sensor output value G have a relationship as shown in FIG. 7, basically this relationship is stored as a table across the required temperature range and the gas sensor output range. At the time of measurement, the gas sensor output value G,
The concentration may be obtained by referring to this table according to the temperature T. However, since such a method requires a large storage capacity, this embodiment employs the following method.

As shown in FIG. 7, the relationship between the temperature T and the gas sensor output value G is shown for each constant concentration, for example, G = f _{10 (T)} T: temperature G: gas sensor value 10: 10% at 10%. It is stored as an approximate expression such as a subscript.

Actually, the respective concentrations of 0%, 5%, 10%, and 15% are stored in the form of the above approximate expressions.

In the measurement, for example, if the gas sensor output value G is a and the temperature measurement value T is b, the point C obtained from this is the approximate expression of 10% and 5% in the case of FIG. Of 3 /
Since it is at the position of 5, it can be proportionally calculated that the concentration at this time is 8%. In this example, the memory is stored every 5%, but if the memory is stored at every 1%, for example, the accuracy can be further improved.

Step 4 (S-4) The alcohol concentration measured value thus obtained is displayed in% on the display unit 13
To display on the digital display 37 provided in
The operator's flight is over. At the same time, the temperature is also digitally displayed.

Step 5 (S-5) Comparison with the set concentration In this step, the alcohol concentration in the dampening water calculated in Step 3 is compared with the concentration preset by the digital switch 36 of the display unit 13, If the measured value is lower than the set value, open the solenoid valve 12, add alcohol (step 5), and if it is higher than the set value, or if it is within the predetermined tolerance centered on the set value, I don't do anything.

In this embodiment, since the capacity of the dampening water tank 1 is limited, if the alcohol concentration is too high, dampening water without alcohol is added to reduce the concentration. Such control is not performed because dampening water may overflow from the tank 1. If there is no such fear, the fountain solution may be added with the alcohol-free fountain solution when the alcohol concentration of the fountain solution is too high. Since the circulating dampening water has a considerable amount, even if alcohol is added, it takes several minutes or more before the alcohol becomes uniform. Therefore, in this example, the amount of alcohol added was an amount commensurate with the difference between the measured value and the set value, and once alcohol was added, for a few minutes,
Even if it detects that the alcohol concentration of the dampening water is too low,
It is designed to prevent the excessive addition of alcohol by not adding alcohol.

Step 6 (S-6) Addition of alcohol In this step, the solenoid valve 12 is opened to add alcohol. As a method of addition, the necessary amount may be added at one time, or may be added in several times for the purpose of uniformly mixing. After step 6 is completed, the process returns to step 1 and the processing is repeated.

FIG. 8 is a block diagram of the entire apparatus, and the operation of each part will be described with reference to the sixth flow chart.

CPU28 controls all motion calculations,
Stores data such as sensor sensitivity and programs
A ROM 26 and a RAM 27 for executing a program are connected to the data bus 29. The RAM 27 is backed up by the battery.

First, in steps 1 and 2, the CPU 28 A / D-converts the signal of the high-temperature sensor 17 and the signal of the gas sensor 18 by an A / D converter 30 through an amplifier (not shown), respectively.

In step 3, the CUP 28 determines the alcohol concentration from the temperature and gas concentration signals fetched in steps 1 and 2 by the ROM 26,
The calculation is performed according to the data stored in the RAM 27. In step 4, the alcohol concentration and temperature calculated in step 3 are given to the digital display 37 via the I / F 31, and the alcohol concentration and temperature are displayed.

In step 5, the target value set by the digital switch 36 is read through the I / F 33, compared with the calculated alcohol temperature in step 3, and is within the allowable range set by the high and low and the digital switch 24. Or not.

In step 6, when the alcohol concentration is lower than the set value, the solenoid valve 12 is opened and closed for a required number of times or for a required time through the I / F 32, and a required amount of alcohol is added.

By the way, in the above-mentioned embodiments, the control system is mainly composed of the microcomputer, but in the present invention, an analog circuit or a hard wire logic circuit may serve the same function.

In particular, if the dampening water in the dampening water tank 1 is configured so as to be accurately maintained at a predetermined constant temperature, it is not necessary to measure and correct the temperature, and the dampening water is directly dampened from the sensor output. Since the alcohol concentration in water can be measured, a thermometer is not required and the configuration can be simplified.

〔The invention's effect〕

As described above, according to the present invention, since the concentration of each component in the mixed solution can be accurately detected by a well-known gas sensor, it is easy to handle continuously without being influenced by dirt or the like mixed in the solution. It is possible to provide a device for measuring the concentration of a mixed solution capable of measuring the concentration.

[Brief description of drawings]

FIG. 1 is an enlarged sectional view of a detection unit in an embodiment of a mixed solution concentration measuring device according to the present invention, FIG. 2 is an overall configuration diagram showing an embodiment of the present invention, and FIG. 3 (a) is a closed space. FIG. 4B is a sectional view taken along line AA ′ in FIG. 4, FIG. 4 is an external view showing an example of the gas sensor, FIG. 5 is a circuit diagram for measuring the gas sensor, and FIG. 6 is an operation. An explanatory flow chart, FIG. 7 is a characteristic diagram for explaining the concentration detecting operation, FIG. 8 is a block diagram mainly showing the control section in one embodiment of the present invention, and FIG. 9 is alcohol dampening in offset printing. It is explanatory drawing which shows an example of a system. 1 ... Damping water tank, 2 ... Pump, 3 ... Water boat, 4 ...
... Roller group, 5 ... plate cylinder, 6 ... plate, 8 ... detector, 9
...... Bypass pipe, 10 ...... Return pipe, 11 ...... Control part, 12 ...... Solenoid valve, 13 ...... Display part, 14 ...... Shield plate, 16 ・ ・ ・
… Lid, 17 …… Temperature sensor, 18 …… Gas sensor, 19
...... Gutter-shaped part, 20 ... closed space, 21 ... dampening water, 22 ...
… Air pump, 23 …… pipe, 24 …… measuring room, 25 …… sensor cap.

Claims (3)

[Claims] 1. A predetermined space containing a liquid surface of a mixed solution whose concentration is to be detected is defined, and a component in the mixed solution is detected based on a detection result of a concentration of a component gas evaporated from the liquid surface in the predetermined space. In a concentration measuring device of a method of detecting a concentration, a measuring unit consisting of a predetermined container to which the mixed solution is supplied, and a measuring unit which is installed in the measuring unit and keeps the liquid level of the mixed solution in the measuring unit at a constant height A return pipe for keeping, a trough-shaped member installed so as to cover the liquid surface of the mixed solution from above and partitioning the predetermined space, and outside air in the space partitioned by the trough-shaped member. A gas flow means for circulating the gas and a gas detection means installed in the passage on the discharge side of the outside air from the space are provided, and the component concentration of the mixed solution is continuously detected based on the detection result of the gas detection means. Is configured to Concentration measuring apparatus of the mixed solution, wherein. 2. The concentration measuring device for a mixed solution according to claim 1, wherein the concentration of the mixed solution is controlled based on the detection result of the component concentration. 3. A concentration measuring device for a mixed solution according to claim 1 or 2, wherein the mixed solution is a fountain solution for offset printing.