JPS6227406Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a doctor for a curved concave marking roll of a gravure printing machine.

As is well known, gravure printing machines require a doctor to scrape off excess ink after ink is applied to the surface of the stamp plate. In general, this doctoring method is divided into a forward doctoring method in which the doctor is applied in a direction that follows the rotational direction of the marking roll as shown in Figure 1, and a reverse doctoring method in which the doctoring is performed against the rotational direction of the marking roll as shown in Figure 1. There is. In the figure, 3 is a marking roll, and 4 is a doctor which is an ink scraping tool. This is mainly used depending on the properties of the ink. For example, when using relatively slow-drying ink, the fluidity of the ink still remains when scraping, making it easier to scrape off. Therefore, when using the forward doctoring method and using quick-drying ink, the reverse doctoring method must be used because drying has already begun when scraping.
In the case of this reverse doctor method, the contact resistance between the tip of the doctor and the marking roll plate surface is large, so that the tip is subject to severe wear.
If the doctor does not apply even pressure to the plate surface of the marking roll, spots will form when scraping off the ink, which will have a negative impact on printing accuracy.
Therefore, in the case of the reverse doctor method in which the tip of the doctor is severely worn out, operations such as adjustment and replacement of the doctor are necessary as appropriate.

In the case of a reverse doctor for a normal cylindrical marking roll, the point of contact between the doctor and the marking roll is a straight line, so the tip of the doctor wears out in a straight line, making it relatively easy to adjust the degree of application of the doctor. It is also less likely to cause scratching spots. (For example, see numerals 9 and 11 in the drawings of Japanese Patent Publication No. 52-45242.) However, since the ink must be scraped off against the concave surface of the curved concave marking roll, the engaging portion at the tip is convexly curved. With a flat doctor, it is difficult to maintain uniform pressure at each point of contact with the plate surface, and ink scraping spots are likely to occur.

On the other hand, the full specification of Japanese Utility Model Application Publication No. 48-66606 discloses a squeegee holder for a screen printing machine that uniformizes the pressing force of the squeegee against the curved printing surface of the printing material. This squeegee is similar to the doctor doctor in that it has the function of applying a uniform pressing force to the printing surface, but since it is formed in a flat plate shape, it cannot apply a uniform pressure as mentioned above. Difficult to maintain.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a curved concave marking doctor capable of maintaining uniform pressure on the surface of a marking roll.

According to the present invention, in a doctor that scrapes excess ink on the surface of a curved concave stamp roll in a gravure printing machine in a direction opposed to the rotational direction of the roll,
The edge of the steel strip is curved so as to contact at least tangentially with the engraved surface of the roll.

Therefore, the edge of the doctor is curved and tangentially adheres to the engraved surface of the roll, making it possible to maintain uniform pressure on the engraved surface, thereby preventing the occurrence of ink scraping spots and reducing wear. can do.

Embodiments of the present invention will be described below with reference to FIGS. 2 and 3.

In FIG. 2, a doctor 1a is attached to the side surface 2a of the tip of the doctor holder 2, and the doctor 1a bends the steel band around the longitudinal axis so that the tip 5a becomes semicircular. It is molded. Further, in the embodiment shown in FIG. 2, the doctor 1b is attached to the tip surface 2b of the doctor holder 2, and in this embodiment, the steel strip is curved in the longitudinal direction to form a cylindrical tip 5b. . In the embodiment shown in FIG. 2, the doctor 1c is made of a cylindrical steel band and is attached to the side surface 2a of the tip of the doctor holder 2.

The doctor who has implemented the present invention is capable of applying the band in a direction opposite to the rotational direction of the marking roll, at least in the range where it contacts the engraved part of the curved concave marking, so that the edge of the band is in close contact with the concave surface of the marking roll tangentially. It is made of curved steel. Therefore, in addition to those illustrated in FIG. 2, various structures can be used depending on the situation.

FIG. 3 is a perspective view when the doctor according to the present invention shown in FIG. 2 is applied to the curved concave stamp 6.

As shown in the figure, the tip 5a of the doctor blade 1a is in contact with the concave surface 6a of the curved concave stamp 6. The range of contact may be at least the engraved portion of the stamp 6, but it may contact the entire surface of the concave surface 6a.

As described above, since the present invention is formed by bending a steel band made of a steel material that can be obtained at low cost, it has excellent adhesion and followability to the concave surface 6a of the stamping roll 6, and the ink can be easily scratched. In addition to being able to remove unevenness, it also has excellent effects such as being able to be manufactured at low cost.

[Brief explanation of the drawing]

Figure 1 is a plan view showing the forward doctor method.
The figure is a plan view showing the reverse doctor method, Figure 2 is a perspective view showing one embodiment of the present invention, Figure 2 is a perspective view showing another embodiment, and Figure 2 is a perspective view showing still another embodiment. FIG. 3 is a perspective view showing a doctor according to the present invention scraping off ink from a concave surface of a curved concave stamp. 1a, 1b, 1c...Doctor, 2...Doctor holder, 5a, 5b...Tip, 6...Curved concave stamp, 6a...Concave surface.

Claims (1)

[Scope of utility model registration request] In a doctor that scrapes excess ink from the surface of a curved concave engraved roll in a gravure printing machine in a direction opposed to the rotational direction of the roll, the edge of the steel strip is curved to be at least tangential to the engraved surface of the roll. A curved concave engraving doctor characterized by being formed to fit closely together.