JP3213705B2 - Ink viscosity controller - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for automatically adjusting the viscosity of ink in a printing press, particularly in a flexographic printing press.

[0002]

2. Description of the Related Art Since a flexographic printing press uses a low-viscosity water-based ink having good fluidity, drying of the ink is extremely fast, and the printed sheets can be stacked as they are, or the printed sheets can be immediately transferred to the next process sheet. Since it can be supplied to a processing machine and the like, it is widely used as a printing machine for corrugated cardboard sheets and the like.

[0003] Usually, ink used in a printing machine such as a flexographic printing machine or a gravure printing machine is circulated and supplied, and a tube pump is often used as the ink circulation pump. The tube pump presses the elastic tube against the inner surface of the cylinder and deforms it flat by rotating the rotor, which is installed at the center of curvature of the elastic tube, with the elastic tube through which ink passes along the inner surface of the cylinder. Ink can be pumped.

[0004] The aqueous ink used in the flexographic printing machine has a different viscosity depending on the kind of color even at the same concentration, and the viscosity is determined in the ink container so as to obtain an appropriate concentration at the start of use. Adjusted. In these water-based inks, the water in the ink evaporates with the passage of time during circulating use, and the ink becomes thicker and thicker.
As the viscosity of the ink increases, the pressure at which the ink is pumped by the pump increases.

As described above, the water-based ink used in a flexographic printing machine is inherently low in viscosity, so that even if the viscosity is slightly increased, the ink will not be clogged in the ink circulation path. There is a problem in that the amount of ink used per printing area increases and the printing cost increases.

As a device for adjusting the viscosity of the ink being used,
There is one disclosed in Japanese Patent Publication No. 2567223.
Although this viscosity adjusting device is mainly intended for a gravure printing machine, as shown in FIG. 3, a pump for circulating the ink in the ink pan 52 in which the plate cylinder 51 is immersed,
A diaphragm pump 54 pulsating with compressed air supplied from an air conduit 53 is employed, and the viscosity of the ink is measured by detecting the number of pulsations of the diaphragm pump 54. Based on the measurement result, the solvent from the solvent tank 55 is measured. An electromagnetic valve 57 disposed in the supply pipe 56 is operated by a control circuit 58.

To detect the pulsation rate, as shown in FIG. 4, an exhaust silencer 5 provided in a diaphragm pump 54 is used.
9, a non-contact sensor 61
The monitoring method is adopted.

When this viscosity adjusting device is used in an existing printing press, an existing tube pump or the like cannot be used as an ink circulation pump, so that these need to be replaced, and the cost of remodeling becomes high. . Also,
Even when used in a new printing press, the diaphragm pump requires ancillary equipment such as a compressor, and the method of detecting the pulsation rate requires a long ink pipe on the pump outlet side, so the equipment is large. Becomes

[0009]

SUMMARY OF THE INVENTION An object of the present invention is to provide an ink viscosity adjusting device which can be simply and compactly mounted on a printing press.

[0010]

In order to solve the above-mentioned problems, an ink viscosity adjusting device according to the present invention is directed to an ink supply side of an ink circulation path for circulating an ink in an ink container to a printing section by a pump. A pressure sensor that is provided in the passage and detects the pressure of the ink being fed; an opening / closing valve that opens to the ink circulation passage to supply a diluting liquid; and a supply pipe connected to the pressure sensor and the opening / closing valve Comparing the preset ink pressure upper limit value with the pressure of the ink supply path detected by the pressure sensor, and opening the on-off valve when the detected pressure exceeds the pressure upper limit value. It employs a configuration including a controller that performs the operation.

That is, a pressure sensor is provided in the ink supply path of the ink circulation path, and the pressure of ink pressure detected by the pressure sensor is compared with an upper limit value set in a controller. When the pressure exceeds the upper limit, the controller opens the on-off valve interposed in the liquid supply pipe and supplies diluent to the ink circulation path.Simple and compact equipment automatically adjusts the viscosity of ink. To be able to do it. As the on-off valve, an electromagnetic valve having a fast response may be used.

[0012]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a viscosity adjusting device for an ink of the present invention installed in a flexographic printing press. This viscosity adjusting device feeds ink in an ink container 1 to a tube pump 2
The diaphragm type pressure sensor 6 and the solenoid valve 7, which are provided in the ink supply side path 5a of the ink circulation path 5 for circulating and supplying between the anilox roll 3 and the doctor roll 4, which are in contact with each other, It is provided with a liquid supply pipe 8 that is interposed and opens in the ink container 1 and supplies a diluting liquid such as water or an organic solvent, and a controller 9 that operates an electromagnetic valve 7 based on an output of the pressure sensor 6. I have.

In the flexographic printing press, a plate cylinder 10 is provided below the anilox roll 3, and end pans 11 for receiving ink are provided below both ends of the anilox roll 3 and the doctor roll 4. The ink received by the end pan 11 is returned to the ink container 1 by the return path 5b.
Is returned to. A scraper 12 for discharging ink into the end pan 11 at the end of printing is provided above the anilox roll 3 and the doctor roll 4 which are in contact with each other. A water supply pipe 14 for washing is connected.

FIG. 2 shows a control flowchart of the controller 9. In the memory of the controller 9, the upper limit value P _U (i) of the pressure is stored in advance for each ink type (i). First, when the type k of the ink color to be used is input to the controller 9, the upper limit value P _U (k) corresponding to the type k is called in the arithmetic circuit. Incidentally, depending on the color of ink used in each case, it may be set an upper limit value P _U suitable for use ink controller 9.

When the tube pump 2 is started and the circulating use of the ink is started, the controller 9 determines the pumping pressure P of the ink and the pressure upper limit value P _U (k) inputted from the pressure sensor 6 every moment. In comparison, the pumping pressure P is
_{When U} (k) is exceeded, the solenoid valve 7 is opened. The control cycle is set to, for example, 15 seconds in consideration of the ink moving time from the ink container 1 to the position of the pressure sensor 6. The opening time of the solenoid valve 7 is short, for example, about 0.1 second. If the pressure P does not become lower than or equal to the upper limit P _U (k) by this one replenishment of the diluent, the next cycle is performed. The solenoid valve 7 is also opened under control. Note that the pumping pressure P is equal to the upper limit value P _U (k)
In the following cases, it is determined whether or not the tube pump 2 is being started, and if the tube pump 2 is stopped, the control ends.

In the above-described embodiment, the supply pipe for adjusting the viscosity is opened in the ink container. However, it may be connected in the middle of the pipe of the ink circulation path. However, in order to prevent printing unevenness, it is preferable to connect the liquid supply pipe to a return-side pipe. Further, as a sensor for detecting the pressure for feeding the ink under pressure, various pressure sensors such as a Bourdon tube pressure sensor can be used in addition to a diaphragm pressure sensor.

[0017]

As described above, in the ink viscosity adjusting device of the present invention, the pressure sensor is provided in the ink supply side path of the ink circulation path, and the pressure for feeding the ink detected by the pressure sensor is set in the controller. When the detected ink pressure exceeds the upper limit, the controller opens the on-off valve interposed in the liquid supply pipe to supply diluent to the ink circulation path. As a result, the printer can be easily and compactly installed regardless of whether it is a new or existing printing press.

[Brief description of the drawings]

FIG. 1 is an external perspective view showing a printing machine equipped with a viscosity adjusting device according to an embodiment.

FIG. 2 is a control flowchart of a controller in FIG. 1;

FIG. 3 is an external perspective view showing a printing machine equipped with a conventional viscosity adjusting device.

FIG. 4 is an enlarged sectional view of a main part of FIG. 3;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Ink container 2 Tube pump 3 Anilox roll 4 Doctor roll 5 Ink circulation path 5a Supply side path 5b Return path 6 Pressure sensor 7 Solenoid valve 8 Supply pipe 9 Controller 10 Plate cylinder 11 End pan 12 Scraper 13 Solenoid valve 14 Supply pipe

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) B41F 31/02 B41F 31/08 B41F 31/20

Claims (1)

(57) [Claims] An ink circulation path for circulating ink in an ink container to a printing unit by a pump is provided on an ink supply side path, and a pressure sensor for detecting a pressure for feeding ink and an opening / closing valve are interposed. Opening to the ink circulation path,
A liquid supply pipe for supplying a diluent, connected to the pressure sensor and the on-off valve, compares a preset upper limit of the ink pressure with a pressure of the ink supply side path detected by the pressure sensor, When the detected pressure exceeds the upper pressure limit, an ink viscosity adjusting device comprising a controller that opens the on-off valve.