JPH0513411Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to an ink supply tank in an ink supply device of a gravure printing machine.

(Prior Art) An ink supply device of a gravure printing machine immerses a gravure printing plate cylinder in liquid gravure ink in an ink supply tank and rotates it, leaving behind ink in the concave image lines that adheres to the plate cylinder surface. The ink in the flat, non-image areas is scraped off using a gravure doctor, and the ink in the concave areas is transferred to the printed paper surface. This gravure doctor scrapes off ink adhering to the flat non-printing area while constantly contacting the surface of the plate cylinder, which rotates at high speed, with a predetermined pressure.
Particularly, the contact portions at both ends of the plate cylinder in the axial direction are subject to severe wear. Due to wear, iron powder generated from the gravure doctor gets mixed into the ink liquid and disperses as the plate cylinder rotates, and enters the cells of the gravure intaglio plate, causing clogging or adhering to the doctor. , scratches may occur between the plate cylinder and printing defects.

In particular, the iron powder generated from the gravure doctor is extremely small and cannot be easily scraped out even if it is simply collected on the bottom. In addition, gravure ink is mainly composed of pigment and volatile solvent, and as time passes, the solvent component evaporates and the pigment component precipitates.However, in gravure printing, printing machines are often operated in shifts. The ink supply tank is cleaned only a few times a year, and pigment precipitation is eliminated because the ink supply tank is cleaned only a few times a year, and the ink supply tank is cleaned only a few times a year. The ingredients gradually stick to the bottom, but the iron powder remains dispersed in the ink until the ink supply tank is cleaned.

(Purpose of the invention) The invention is to magnetize the ink supply tank to collect the abrasive powder of the gravure doctor mixed in the ink liquid by magnetically attracting it to a certain point, and to disperse it into the liquid gravure ink. The present invention provides an ink supply tank to prevent this.

(Structure of the invention) The present invention uses an electrically insulating member in an ink supply tank for gravure printing that supplies ink to a printing plate while rotating a plate cylinder in which a gravure ink scraping doctor is brought into sliding contact with the printing plate. an outer tank 6 formed by an ink tank, an inner tank 7 removably fitted into the outer tank 6, and an inner tank 7 provided below the bottom 4 of the outer tank 6 to remove metal generated when ink is scraped off by the doctor. This ink supply tank is characterized by having a magnetic field generating device 5 of an electromagnet that collects powder at the bottom of the inner tank 7 by magnetic force.

If the present invention is explained in detail according to the drawings, the first
The figure is a schematic side view of an ink supply tank of a gravure printing machine to explain the gist of the present invention. The gravure plate cylinder 1 is immersed in the ink liquid a of the ink supply tank 3 and is rotating in the direction of the arrow. The tip of a blade of a gravure doctor 2 for ink scraping comes into contact with the circumferential surface of the plate cylinder 1, and scrapes off ink in non-image areas of the ink adhering to the circumferential surface of the plate cylinder 1. An impression cylinder 8 is provided above the plate cylinder 1, and a printing paper 10 is passed between the plate cylinder 1 and the impression cylinder 8 to perform printing. On the upper side of the impression cylinder 8,
A back-up roll 9 is provided to press the impression cylinder 8 downward.

The ink supply tank 3 is provided with a magnetic field generating device 5 such as an electromagnet or a permanent magnet below the bottom portion 4, and the device 5 generates a magnetic field from the bottom portion 4 toward the ink liquid a. The magnetic field generating device 5 is configured such that, for example, all N poles or S poles are located on the bottom 4 side. However, if a too strong magnetic field is generated, the plate cylinder 1 may be temporarily magnetized and metal powder may adhere to the circumferential surface of the plate cylinder 1. It is necessary to set the magnetic field strength.

In the present invention, a magnetic field generating device such as an electromagnet or a paramagnetic magnet is not only provided on the bottom portion 4 but also may be provided on the side wall of the ink supply tank.

FIG. 2 is a side view of another embodiment of the ink supply tank of the present invention. The ink supply tank 3 consists of an outer tank 6 and an inner tank 7 that fits into the tank 6. For example, the outer tank 6
can be formed from an electrically insulating material such as synthetic resin. The metal powder collected by the magnetic force on the bottom of the ink supply tank 3 is periodically removed by turning off the power 11 of the magnetic field generator 5 and taking out the inner tank 7 above the outer tank 6. Try to remove it in the opposite direction.

(Function of the invention) According to the invention, the iron powder generated from the gravure doctor is collected at the bottom by the magnetic field and at the same time incorporated into the precipitated pigment component, thereby preventing it from being redispersed in the ink. By removing the inner tank, you can easily remove the solidified precipitated pigment components and iron powder by hand (or with a scraping tool). ), and even small magnetic objects such as iron powder can be easily removed.

(Effects of the invention) This invention prevents the metal powder mixed and dispersed in the gravure printing ink supply tank from being redispersed in the ink by collecting it at the bottom using a magnetic field and at the same time incorporating it into the precipitated pigment component. Even cleaning the ink supply tank once in a while can prevent iron powder from affecting printing, and eliminates various printing problems caused by metal powder adhering to the printing plate cylinder or gravure doctor. By removing the inner tank, solidified precipitated pigment components and iron powder can be easily removed by hand (or with a scraping tool). Even small magnetic objects such as iron powder can be easily removed, which is effective for cleaning and maintenance of gravure printing machines and ink supply tanks, and has practical value.

[Brief explanation of the drawing]

Figure 1 is a side view of one embodiment of the device of the present invention;
The figure is a side view of another embodiment of the device of the present invention. 1... Plate cylinder, 2... Doctor, 3... Ink supply tank, 4... Bottom, 5... Magnetic field generator, 6...
Outer tank, 7...inner tank.

Claims (1)

[Scope of Claim for Utility Model Registration] In an ink supply tank for gravure printing, in which ink is supplied to the plate surface while a plate cylinder with a gravure ink scraping doctor in sliding contact with the plate surface is immersed and rotated, on an electrically insulating member. an outer tank 6 thus formed; an inner tank 7 removably fitted into the outer tank 6; and an inner tank 7 provided below the bottom 4 of the outer tank 6 to remove metal powder generated when ink is scraped off by the doctor. An ink supply tank characterized in that it has a magnetic field generating device 5 of an electromagnet that collects the ink at the bottom of the inner tank 7 by magnetic force.