JPS631543A - Composition management device of moistening water for printing - Google Patents

Abstract

PURPOSE:To perform the composition management highly accurately by means of a small and easy-to-handle device, by providing an alcohol concentration detector, a temperature detector and a hydrogen ion concentration detector in order to detect the composition of moistening water being fed to a printing machine and to control the addition of specific solute into the moistening water on the basis of the detection result. CONSTITUTION:In case of an alcohol dampening system for an offset printing machine, a portion of moistening water being fed from a pump 2 toward a vessel 3 is taken through a bypass pipe 9 at a detecting section 8 of the device, then measured and returned through a pipe 10 to a moistening water tank 1. On the basis of signals fed from various sensors arranged at a detection section 8, a control section 11 calculates the temperature of the moistening water, the alcohol concentration and the pH level then controls such that the composition and the temperature of the moistening water converge to the levels preset by a digital switch based upon the detection result. Since all sensors necessary for control are collected in the detecting section 8, the structure is simplified and the handling is facilitated resulting in an almost completely automated control.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a silk forming and embedding apparatus for an aqueous solution containing alcohol as a main solute, and particularly to a composition of dampening water used in offset printing. The present invention relates to a suitable printing dampening water composition tube embedding device.

[Background of the invention]

As is well known, in offset printing, it is necessary to apply ISCL water to the plate surface. As a device for applying this dampening water to the printing plate, that is, a dampening water device, the so-called Morton type, which uses Molton water-retaining cloth as a roller for applying water to the printing plate, has been widely used.

However, in recent years, the so-called alcohol dampening system, which does not use a Molton roller to supply water to the printing plate, has replaced the Molton method described above, due to the ease of maintaining stable image quality and ease of operation and maintenance. It is becoming widespread.

Figure 11 shows an example of this alcohol dampening system.
The trap is designed to maintain a temperature of around °C. This tank 1
The dampening water inside is pumped up by the pump 2 and sent to the printing press's water boat 3K, but a part of the roller group 4 of the dampening water device is installed in this water boat 3, and the dampening water K2 is pumped up by the pump 2. The button is designed to be used. Then, the plate 6 is taken out by the dampening roller group 4 in the water boat 3 and wrapped around the plate cylinder 5K.
It will be supplied to the surface of

On the other hand, the excess dampening water 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 sinutem,
The roller itself that applies water to the printing plate does not have strong water retention properties like the Molton roller, so in order to supply sufficient dampening water to the printing plate, it is necessary to add a surfactant such as alcohol to the dampening water. It is said that it is necessary to reduce the surface tension and make it easier for water to disperse in the ink.

Currently, the most commonly used surfactant among alcohols is Impropeel alcohol, and the alcohol concentration in dampening water is usually 5% to 20%. However, this change in alcohol concentration, the amount of water supplied to the inking device, that is, the amount of water supplied to the printing plate, and the amount of water K that is supplied to the printing plate have a very large effect on the quality of printed matter.

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

However, the conventional method for measuring alcohol concentration has been to take advantage of the fact that the specific gravity of alcohol is lower than that of water, and measure the specific gravity of dampening water using a pycnometer to determine the alcohol concentration. It was used.

However, in the above-mentioned alcohol dampening system, dampening water is usually pumped into a water tank on the printing press.
Since the dampening water is circulated between tanks, the K in the dampening water is mixed with many fine air bubbles, which adhere to the specific gravity pin, making it difficult to measure the concentration correctly. Furthermore, ink and dirt in the dampening water that adhere to the pycnometer cause measurement errors, requiring frequent cleaning, making handling complicated.

In addition to the above-mentioned addition of alcohol to dampening water for printing, it has long been known to add a solution called H solution, in which gum arabic is dissolved in an aqueous phosphoric acid solution.

In other words, in offset printing, dampening water is supplied to the plate surface as described above, and a water-retentive protective film is formed in the area without a pattern (non-image area), and the ink is attached to the non-image area. However, at this time, water is not sufficient as a retention film, so
It is also necessary to add the H solution as described above.

When the concentration of this H solution in the dampening water changes, the Hoto film mentioned above also changes, resulting in a change in printing quality.
This will have a negative impact.

Therefore, in such a dampening water for printing, in addition to controlling the alcohol concentration described above, controlling the H liquid at 9 ftf is also an important requirement.

By the way, when controlling the concentration of this H solution, it is of course necessary to detect it, but since this H solution is acidic, the PH degree of 5 liters of water This can be easily handled by measuring (hydrogen ions @ degree). Therefore, conventionally, the PH value has been measured using a commercially available PH meter, and the concentration has been controlled based on this result.

In addition, in recent years, dampening water containing sodium silicate, sodium phosphate, etc., instead of the above-mentioned liquid I-1, so-called alkaline dampening water, has become popular in some areas. Even in this case, it is necessary to control the concentration,
At this time, generally, instead of detecting the pH level of the dampening water, which indicates its concentration, changes in the alkaline content of the dampening water are detected by measuring the conductivity of the dampening water. There is.

In this way, it is necessary to control the alcohol concentration and PI-1 degree of dampening water for printing, and detection of these is essential, but conventionally, for this purpose, K pycnometer bottles were used as described above. Furthermore, individual K was measured using a PH meter or a conductivity meter.

[Purpose of the invention]

The present invention has been made against the above-mentioned background, and its purpose is to manage the composition of printing dampening water, such as the alcohol concentration and pH value, using a compact and easy-to-handle device. It is an object of the present invention to provide an apparatus for controlling the composition of a printing dampening water that can perform the composition control with sufficient K accuracy.

[Summary of the invention]

In order to achieve this objective, the present invention bypasses the dampening water circulating between the printing press and the tank, and in this bypass section, the detection necessary to detect the alcohol concentration and composition of the dampening water is provided. The feature is that it does everything.

[Embodiments of the invention]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The composition management device for printing dampening water according to the present invention will be described in detail below with reference to illustrated embodiments.

Fig. 2 shows an embodiment of the present invention applied to an alcohol dampening system for an offset printing machine. 8 is a detection unit of this device, and dampening water is sent from pump 2 toward Mizufune 3K. One portion is collected through a bypass pipe 9 and returned to the dampening water tank 1 through a pipe 10 after measurement.

Reference numeral 11 denotes a control unit that calculates the temperature of the dampening water, its alcohol concentration, and the same <PH value based on the signals K from various sensors provided in the detection unit 8, and calculates the temperature of the dampening water based on these detection results K. The composition and temperature of water are controlled so that they converge to a predetermined value K set in advance using a digital switch or the like.

That is, if the temperature deviates from a predetermined value, a temperature controller (not shown) is controlled accordingly to heat and cool the dampening water in the tank 1, so that the dampening water settles to a predetermined temperature, and the alcohol concentration is reduced. When the pH value decreases from a predetermined value, the solenoid valve 12 is opened and closed to replenish alcohol and return to the predetermined alcohol concentration.When the pH value rises from the predetermined value (that is, the concentration of the H liquid decreases), the solenoid valve 13 is opened and closed. Controlled Hg. The oPH value is replenished to return to a predetermined oPH value.

A display section 14 is equipped with a digital display iW 14A and a digital switch 14B, and is configured to digitally display the detected temperature, alcohol concentration, and PH value, and also allows the above-mentioned predetermined values to be set.

FIG. 1 is an enlarged cross-sectional view of the detection section 8. When the dampening water collected through the bypass pipe 9 enters the detection section 8, it passes under the dampening plate 15. This shielding plate 15 serves to prevent waves from occurring on the water surface within the detection unit 8. On the other hand, the return pike 10 is shaped to protrude into the detection part 8, and keeps the water surface level in the detection part 8 constant at all times, and returns excess dampening water to the dampening water tank IK. do the work.

A temperature change sensor 18, a gas sensor 19, and a PH sensor 20 are attached to the lid 17 of the detection unit 8. In this example, since the H solution is added to the dampening solution, a PH sensor 20 is provided accordingly. However, when using the above-mentioned alkaline dampening solution, A conductivity sensor may be provided in place of this PH sensor 20, and according to case K, P
Both the l-T sensor and the conductivity sensor may be provided together so that it can be applied to any dampening solution.

Next, the operation of this embodiment will be explained for each sensor.

Note that the temperature sensor 18 may be one using a well-known ++--mister, etc., and one of its parts simply detects the temperature of the dampening water, and controls the temperature of the dampening water and alcohol concentration described above. I
Y Since it is only used for correction in case of sudden emergence (described later) and for display, independent wisdom is omitted. ■. Detection and Control of Alcohol Concentration In Fig. 1, the sensor cap 21 has a cylindrical shape when viewed from above, and its lower part is slightly below the surface of the dampening water.
5K to form a small sealed space 22 including the interface with the dampening water. The gas sensor 19 detects the alcohol gas vaporized from the interface of the sealed space 22 and filled in the space 22, and generates a signal representing the gas concentration.

This gas sensor 19 is a well-known catalytic combustion type gas sensor as shown in FIG. 3K, and consists of a measuring element 19a and a dummy 19b as shown in FIG. Note that the sensor used in the present invention is not limited to such a catalytic combustion type sensor, but may be any sensor that exhibits the required detection characteristics for alcohol gas K, such as a semiconductor sensor. Any type of sensor may be used, such as a type sensor, an infrared absorption type sensor, a thermal conduction type sensor, or a light wave interferometer sensor. The sensor cap 21 is made removable, so that it can be easily removed when there is a risk of being contaminated or affected by K, and the interior can be easily cleaned by kneading, and the sensor etc. can also be easily replaced. It has become.

Reference numeral 25 denotes an air pipe, which serves to send fresh air from an air pump provided in the control unit 11 into the sealed space 22 partitioned by the sensor cap 21, and thereby discharge old air to the outside via the pipe 26. .

FIG. 5 is a flowchart showing the alcohol concentration measuring operation, and each step will be explained below.

Step 1 (S-1) The ventilation air pump inside the sensor cap 21 is activated to exhaust the alcohol gas inside the sensor cap 21. As a result, the inside of the cap is ventilated and there is almost no alcohol gas.

Ventilation inside the cap is based on the following burial grounds.

If the measurement is continued with the K cap 21 covered above the water surface of the dampening water 23, the alcohol gas concentration in the cap will quickly change as the alcohol concentration in the dampening water 23 increases. K increases, and sensor 1 can quickly detect changes in alcohol concentration in water. However, when the alcohol concentration in the dampening water decreases, the higher concentration of gas
Since the gas concentration in the sensor cap decreases due to the VcFM remaining in the water, the sensor detects the change in alcohol concentration in the water quite late. This is because the air inside the sensor cap is once exhausted, and then the concentration of vaporized alcohol gas is measured according to the alcohol concentration at that point.

Step 2 (S-2) Stop the pump - for a fixed period of time, or if the inside of the sensor cap 21 is damaged.
After ventilating until the air is completely dry, stop the air pump. At this time, the air pipe 25 and the exhaust pipe 26 should be made appropriately thin and long, so that after the pump is stopped, the inside of the sensor cap may be affected by K such as wind outside the detection part 8, or gas may leak out from inside the cap. Try not to get too busy.

Step 3 (S-3) Waiting step l~ for a certain period of time
In the sensor cap 21, which has been sufficiently ventilated in step 2, alcohol gas will eventually vaporize, and the alcohol concentration in the dampening water at that point and the temperature of the dampening water will become constant! It is filled with gas.

Therefore, K takes a corresponding amount of time.

Therefore, in this embodiment, the time required for this purpose is assumed to be 1 minute and 30 seconds, and the alcohol content detection process is kept on standby during this time. During this standby process, K performs PH measurement (or conductivity measurement) and temperature measurement processes, which will be described later.

Step 4 (S-4) Capturing the signal Capturing the gas sensor signal. In this embodiment, in order to improve accuracy, signals are repeatedly captured 10 times or more, and their average value is finally used as the sensor signal.

Step 5 (S-5) Calculation of alcohol concentration In this step, the alcohol concentration in the dampening water is calculated as follows using the gas sensor output value acquired in step 4K and the liquid temperature value acquired in another process described later. The calculation process is performed as follows. In other words, the liquid temperature. The relationship with the gas sensor output value is as shown in FIG. Therefore, this relationship is stored as a table for every 1% concentration, for example, and the concentration is determined by referring to this table from the liquid temperature and the gas sensor output value.

Step 6 (S-6) Display of Alcohol Concentration The measured value thus obtained is displayed as a percentage on the digital meter 14A provided in the display section 14 for the convenience of the operator.

Step? (S-7) Comparison with the set concentration In this step, the alcohol concentration in the dampening water already calculated in step 5 is compared with the digital switch 14B of the display section 14.
If the measured value is lower than the set value, open the solenoid valve 12 and add alcohol (step 8 described later); if the measured value is higher than the set value, or If K is within the specified tolerance range, do nothing in particular.

In this example, since the capacity of the dampening water tank l is limited, if the alcohol concentration is too high, dampening water without K alcohol added is added to lower the concentration. Such control is not carried out because there is a risk that the dampening water will overflow from the tank l. However, if there is no such risk, the fence may be configured to add dampening water to which no alcohol has been added when the alcohol concentration of the dampening water is too high.

By the way, since there is a considerable amount of circulating dampening water, even if alcohol is added, it takes several minutes or more for the alcohol to be uniformly distributed. Therefore, in this example, the amount of alcohol added is adjusted to the difference K between the measured value and the set value, and once alcohol is added, it is detected that the alcohol content of the dampening water is too low for several minutes. However, in some cases, alcohol is not added to prevent adding too much alcohol.

Step 8 (S-8) Addition of Alcohol This step is a process of adding alcohol by opening the solenoid valve 12. As for the method of addition, the required amount may be added at once, or it may be added in several portions in order to mix uniformly.

Although the explanation may be confusing, Figure 7 shows only the parts necessary for control, centering on the control unit 11, as blocks. A ROM 31 that stores data such as sensitivity and programs and a RAM 32 necessary for executing the programs are connected via a data bus 33.

Signals from sensors such as the gas sensor 19 are input to the kp from each amplifier via a common A/D, while signals from the solenoid valve 12 and other devices are input to the respective I/Ds.
/F is busy transmitting signals, which causes the processing in each step of FIG. 5 to be executed.

II PH value detection and control The PH sensor 20 has a measuring electrode 20 as shown in FIG. 8K.
A. The reference electrode 20B and the temperature change sensor 20C are connected to the support tube 20.
It is of a composite glass electrode type integrated with D, and is configured to obtain the PH value using an impedance star conversion circuit 20J consisting of an operational amplifier and a temperature compensation circuit 20K consisting of an AGC amplifier, as shown in Fig. 9. This is a well-known thing. In addition, in Fig. 7, 20E is a PH made of a glass thin film.
20F is a glass electrode internal solution, 20G is a reference electrode internal solution, 20H is a reference electrode internal solution replenishment port, and 20F is a reference electrode liquid junction.

However, when implementing the present invention, the present invention is not limited to such a composite glass electrode type PH sensor, and other materials may be used.
It goes without saying that a sensor that detects the PH value based on K may also be used.

As already explained, this PH value detection process is executed together with the temperature detection process between steps 2 and 3 in FIG. 5, and this will be explained below with reference to the flowchart in FIG. 10.

In step 9 (S-9), the signal from the PH sensor 20 is digitized by the A/D and read.

In step 10 (S-10), PH@
In step 11 (S-11), the calculated PH value is given to the digital display 14A to display the current value of PH.

In step 12 (S-12), the PH value previously set by the digital switch 14B is compared with the current PH detection value.

In step 13 (S-13), when the result in step 12 is YES, that is, when the detected pH value is higher than the set value (H liquid concentration decrease), the vL magnetic valve 13 is controlled to In this example, only the acidic H liquid is used, and the pH is controlled by direction control using K only for the addition of the H liquid. may be used to control the pH by using these in combination.

In addition, in such cases, as already explained, a conductivity sensor may be used in place of or in conjunction with the PH7 sensor, especially when only alkaline H solution is used. As mentioned above, it is also possible to use only the conductivity sensor without using the PH sensor.

Steps 9 to 13 above complete the processing necessary for detecting and controlling the PH value, and then temperature detection and control K begins.

In step 14 (S-14), the signal from the temperature sensor 18 is digitized and captured.

In step 15 (S-15), the temperature sensor output value is converted into a temperature value. As described above, a thermistor is used as the temperature sensor 18 in this embodiment. Therefore, an equation representing the relationship between temperature and the output voltage of this thermistor should be stored in the ROM 31K in advance, and the temperature should be determined by performing conversion according to this equation.

In step 16 (S-16), the temperature calculated in this way is displayed on the digital display 14AK.

In step 17 (S-17), the temperature target value set in advance by the digital switch 14I3 and the step 1
, and the measured temperature calculated in step 5.

In step 18 (S-18), when the result in step 17 is YES, that is, when the measured temperature is higher than the target temperature value, the cooler in the temperature controller is activated, and the Let the dampening water inside cool down.

In step 19 (S-19), when the result in step 17 is NO, processing is performed to stop the operation of the cooler.

Generally, the temperature of the dampening water tends to rise while the printing press is operating. Therefore, in this embodiment, the temperature of the dampening water is adjusted only by turning on and off the cooler, but it is also possible to use a temperature controller that has both heating means and cooling means. Needless to say.

Therefore, according to this embodiment, all the sensors necessary for the detection section 8KI1@ are integrated, so that the configuration is simple and the handling becomes easy.

Furthermore, according to this embodiment, almost no manual operation is required, almost completely automated control is obtained, and the dampening water can always be kept in the best desired state.

Furthermore, in the above embodiment, the alcohol 19 in the dampening water is detected from the concentration of alcohol gas in a predetermined sealed space that includes the surface of the dampening water as an interface. It is possible to easily detect and control the alcohol concentration in the dampening water with high precision, regardless of air bubbles or dirt such as ink mixed in the dampening water.

〔Effect of the invention〕

As explained above, according to the present invention, all the various sensors necessary for determining the composition of fresh water are integrated into the detection section, so there is no need for individual manual detection operations as in the prior art. It is possible to easily provide a composition management device for printing dampening water that is small and easy to handle.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing an embodiment of the detection unit in the printing dampening water composition control device according to the present invention, and FIG. 2 is an explanatory diagram showing an embodiment of the detection unit in the printing dampening water composition control device according to the present invention. 3 is an external view showing an example of an alcohol gas sensor, FIG. 4 is a circuit diagram of an alcohol gas sensor, FIG. 5 is a flowchart showing the operation process in an embodiment of the present invention, and FIG. A characteristic diagram of an alcohol gas sensor, FIG. 7 is a block diagram showing the configuration of an embodiment of the present invention centering on the control section, FIG. 8 is an explanatory diagram showing an example of a PH sensor, and FIG. 9 is a P H sensor. M
A circuit diagram of the sensor, FIG. 10 is a flowchart showing other operational processing in an embodiment of the present invention, and FIG. 11 is a block diagram showing an example of a conventional alcohol dampening system. 8. ．． ．． ．． ．． ．． Detection unit, 9, . ．． ．． 、． Bypass valve, 10. ．． ．． ...Return pipe, 11...
・Control unit, 12, 13... Solenoid valve, l4...
...Display section, 15...Shiyahei board, 17...
... Lid, 18 ... Temperature sensor, 19.
... Gas sensor, 20...PH sensor, 21...Sensor cap, 22...
...Closed space, 25... Air pipe. Figure I I8 Osamu/t{? Scissor Figure 2 Figure 3 Figure 4 l9 No. 4 output Figure 5 Figure 6 Figure 8 Figure 7 wEIO diagram

Claims (4)

[Claims] (1) Detect the composition of dampening water supplied to the printing machine,
In a printing dampening water composition control system that controls the addition of a predetermined solute to the dampening water based on the detection results, a portion of the dampening water circulating between the printing machine and the supply tank is introduced. A composition of a dampening solution for printing, characterized in that a bypass section is formed so that the dampening solution passes through the bypass section, and all the detectors necessary for the detection process of the above-mentioned composition are installed in the bypass section. Management device. (2) In claim 1, the detector comprises:
A composition management device for printing dampening water, comprising at least three types of detectors: an alcohol concentration detector, a temperature detector, and a hydrogen ion concentration detector. (3) In claim 1, the detector comprises:
A composition management device for printing dampening water, comprising at least three types of detectors: an alcohol concentration detector, a temperature detector, and a conductivity detector. (4) In claim 2, the alcohol concentration detector detects the concentration of alcohol gas in the dampening water based on the detection result of the alcohol gas concentration within a predetermined space formed including an interface with the dampening water. A composition management device for printing dampening water, characterized in that it is configured to detect alcohol concentration.