JPH037152Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a printing device that performs gravure printing, and more specifically, to an improvement of the device for preventing printing defects. The printing device of the present invention can be used, for example, when printing on the surface of a hose.

[Prior Art] Conventionally, a device as shown in FIG. 2 has been used as a printing device for printing, for example, a lot number etc. on the surface of a hose. This device consists of a printing roller 100 with a printing part engraved on its circumferential surface, a reservoir tank 101 in which printing ink is stored, and a reservoir tank 10.
The ink supply nozzle 102 extends from 1 to the circumferential surface of the printing roller 100, and the doctor knife 103 is in elastic contact with the circumferential surface of the printing roller 100.

In this printing device, printing ink stored in a reservoir tank 101 is supplied to an ink supply nozzle 102.
is supplied to the circumferential surface of the printing roller 100 from. Then, as the printing roller 100 rotates, the doctor knife 103 in elastic contact fills the printing section with ink and scrapes off excess ink, so that the ink filled in the printing section is transferred to the hose and printed. It is composed of Note that when printing a long object such as a hose, the hose is generally conveyed in a horizontal direction. Therefore, the printing roller is generally arranged with its axial direction in the vertical direction.

[Problems to be solved by the invention] In the above-described printing apparatus, when the printing apparatus is operated continuously for a long time, the doctor knife 103 and the printing roller 10
There was a problem in which foreign matter intervened between the ink and the circumferential surface of the ink and the ink could not be sufficiently scraped off, resulting in printing defects. Therefore, it is necessary to periodically clean the elastic contact portion between the doctor knife 103 and the printing roller 100, which increases the number of man-hours and causes printing to be stopped during cleaning, resulting in a decrease in productivity.

It has been found that the above-mentioned problems are due to the causes explained below. That is, the printing roller 100
Since the axial direction of the ink is generally arranged in the vertical direction, excess ink scraped off by the doctor knife 103 escapes to both sides of the doctor knife 103 (in the vertical direction). The ink that escapes downward falls below the printing roller 100, but since printing ink generally has a high viscosity, the ink that escapes upward accumulates in a rim shape on the periphery of the upper end surface of the printing roller 100. Then, the solvent contained in the accumulated ink evaporates and gradually solidifies. However, when the printing roller is operated continuously, new ink is constantly accumulated, so that the ink accumulated at the peripheral edge of the print roller end surface is solidified toward the top and soft toward the bottom. Therefore, when the accumulated amount exceeds a certain amount, the lower part of the accumulated material cannot support the upper part, and the solid material at the upper part begins to hang down on the circumferential surface of the printing roller 100. This solid matter is then caught between the doctor knife 103 and the circumferential surface of the printing roller 100, resulting in poor scraping.

This idea was made in view of this situation,
An object of the present invention is to provide a printing device that can prevent scraped ink from accumulating on the end surface of a printing roller.

[Means for Solving the Problems] The printing device of the present invention includes a printing roller whose axial direction is arranged in the vertical direction and a printing section is carved on the circumferential surface, and an ink supply device that supplies ink to the circumferential surface of the printing roller. A device, a doctor knife whose one end is fixed and whose other end is in elastic contact with the circumferential surface of the printing roller, and which fills the printing section with ink as the printing roller rotates and also scrapes excess ink from the circumferential surface; The present invention is characterized by comprising a solvent supply device for supplying an ink-soluble solvent to a part of the printer, and the scraped ink is diluted with the solvent and dropped below the printing roller.

The printing roller, ink supply device, and doctor knife can have the same configuration as conventional ones. In the present invention, the printing rollers are arranged with their axial directions in the vertical direction, but they do not necessarily have to be perpendicular to the vertical direction, and may be arranged at a certain angle with respect to the horizontal plane.

The ink supply device can adopt various conventionally known configurations, such as one that supplies ink using its own gravity or one that pumps ink using a pump.

Doctor knives are generally made of steel plate, etc.
One end is fixed and the other end is arranged so as to come into elastic contact with the peripheral surface of the printing roller.

The most distinctive feature of the present invention is that it includes a solvent supply device that supplies an ink-soluble solvent to the elastic contact portion between the doctor knife and the peripheral surface of the printing roller. With this configuration, the scraped ink is diluted with the solvent supplied by the solvent supply device, and its viscosity is reduced, so it is prevented from accumulating on the upper end surface of the printing roller and almost falls downward. Become. The solvent supplied by the solvent supply device here only needs to be soluble in the ink used, and water can be used in the case of an aqueous ink, and organic solvent can be used in the case of an oil-based ink. Note that if the evaporation rate of the supplied solvent is too fast, it will be difficult to obtain an effect, so it is desirable to use a solvent with a slow evaporation rate. Note that the evaporation rate and supply amount can be variously set depending on the rotation speed of the printing roller, the supply amount of ink, etc.

In order to supply the solvent to the elastic contact part, for example, a solvent supply nozzle may be disposed in the elastic contact part and the solvent may be dripped onto the ink scraped off by the elastic contact part. Alternatively, the solvent can be supplied to one fixed end of the doctor knife and supplied to the elastic contact portion through the doctor knife. Of course, it is desirable that the ink scraped off by the elastic contact portion be supplied from the upper end surface side of the printing roller. It is also necessary to take care to prevent solvent from adhering to the peripheral surface of the printing roller after excess ink has been scraped off.

[Operations and Effects of the Invention] The printing apparatus of the invention includes a solvent supply device that supplies an ink-soluble solvent to the elastic contact portion between the doctor knife and the peripheral surface of the printing roller. Therefore, the ink scraped off by the doctor knife is diluted by the supplied solvent and its viscosity is reduced, so that it falls downward and is prevented from accumulating and solidifying on the upper end surface of the printing roller. Therefore, problems such as solidified solid matter hanging down from the lower end surface of the printing roller and resulting in printing defects are prevented.

Further, the ink that has fallen downward is usually collected and reused. However, when the ink was operated for a long time, the density of the ink increased and the viscosity increased, causing problems with printing, so it was necessary to periodically adjust the density. However, according to the printing apparatus of the present invention, management of ink concentration can be made unnecessary by adjusting the amount of solvent supplied from the solvent supply device. Furthermore, since there is almost no accumulation of solid matter, there is no need to regularly clean the doctor knife, allowing continuous production and improving productivity.

Therefore, according to the printing apparatus of the present invention, even when operated continuously for a long time, a clear printing surface can be maintained on the peripheral surface of the printing roller, and printing can be performed satisfactorily.

[Example] This will be explained in detail below using Examples.

FIG. 1 shows a schematic diagram of a printing apparatus according to an embodiment of the present invention. This printing device prints various numbers, etc. on the surface of the hose, and includes a printing roller 1 whose axial direction is arranged in the vertical direction, a printed part is carved on the circumferential surface, and which comes into contact with the hose 5, and a circumferential surface of the printing roller 1. An ink supply device 2, one end of which is fixed to a holding member 31 and the other end of which is in elastic contact with the circumferential surface of the printing roller 1, fills the printing section with ink by rotation of the printing roller 1 and removes excess from the circumferential surface. Doctor Knife 3 to scrape off ink and Doctor Knife 3
and a solvent supply device 4 for supplying an ink-soluble solvent to a portion in elastic contact with the circumferential surface of the printing roller 1.

The ink supply device 2 is composed of a reservoir tank 21 and an ink supply nozzle 22 that supplies ink stored in the reservoir tank 21, as in the conventional case. The solvent supply device 4 is composed of a solvent storage tank 41 in which a solvent is stored and a solvent supply nozzle 42 extending from the solvent storage tank 41, and supplies the solvent from one fixed end of the doctor knife 3 to the upper end of the doctor knife 3 It is configured to be transmitted and supplied to the other end.

Here, the hose 5 is conveyed horizontally, and the conveyance speed is 50 cm/min.

The ink supplied from the ink supply device 2 is an oil-based ink having a viscosity of 300 to 500 CPS (at 20° C.), and is supplied to the circumferential surface of the printing roller 1 at a rate of 4 ml/sec. Moreover, the solvent supply device 4
A special thinning liquid is supplied to the upper surface of one end of the doctor knife 3 at a rate of 1 ml/sec.

When the printing apparatus of this embodiment configured as described above was used to continuously print on the surface of the hose 5 for 8 hours, the amount of ink accumulated on the upper edge of the printing roller 1 was small. , Doctor Knife 3
Good printing was possible without any problems such as solid matter clogging the elastic contact portion between the roller and the circumferential surface of the printing roller 1.

[Brief explanation of drawings]

FIG. 1 is a schematic explanatory diagram showing the configuration of a printing apparatus according to an embodiment of the present invention. FIG. 2 is a schematic explanatory diagram showing the configuration of a conventional printing apparatus. 1... Print roller, 2... Ink supply device, 3
...Doctor knife, 4...Solvent supply device, 5...
…hose.

Claims (1)

[Claims for Utility Model Registration] A printing roller whose axial direction is arranged in the vertical direction and a printing portion is carved on the circumferential surface, an ink supply device that supplies ink to the circumferential surface of the printing roller, and one end of which is fixed. a doctor knife whose other end is in elastic contact with the circumferential surface of the printing roller, and which fills the printing section with the ink and scrapes excess ink from the circumferential surface as the printing roller rotates; and a fixed portion of the doctor knife. a solvent supply device that supplies a solvent in which the ink is soluble to the one end side of the ink, and supplies the solvent through the upper end of the doctor knife to the elastic contact portion between the printing roller and the doctor knife; A printing apparatus characterized in that the ink is diluted with the solvent and is dropped below the printing roller.