JPS6331397B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is a convex ring, in particular, a mesh roll (also known as amiroll, screened roll or anilox roll) developed as an ink supply system for flexographic printing, which has been modified so that it can be used for offset printing. Concerning special mesh rolls.

It is well known that the use of mesh rolls eliminates the need for large groups of ink cylinders. Therefore,
If this mesh roll could be introduced into offset printing, it would be possible to significantly reduce the size, weight, simplicity, and cost of the offset printing mechanism.
This will be an irreplaceable benefit for the small and medium-sized printing industry, which operates with limited space and little capital.

As a result of repeated numerous tests in order to solve the above problem, the present inventor solved the following difficult problem:
(1) The advantage of eliminating the need for multiple ink cylinder groups is that the return water generated from the water supply, which is a feature of offset printing, flows directly back from the plate cylinder surface to the mesh roll surface via the ink form roll. , and (2) Since the chromium layer of the chrome-plated mesh roll is hydrophilic, water drives away the ink on the roll and reduces the amount of ink on the roll. It was found that the density of the ink that reached the printer was becoming thinner, impeding clear printing, and there was an urgent need to find a technical solution to this problem.

The purpose of the present invention is to solve the above-mentioned problems and create a mesh roll exclusively for offset printing that can prevent the deterioration of ink coverage on the mesh roll surface due to water and smoothly supply ink to the plate cylinder surface. and provide it.

To summarize the concept of the present invention, mesh-like unevenness is machined on the peripheral surface of a steel roll, the unevenness is uniformly covered with a chrome plating layer, and a porous layer is formed on the surface of the chrome plating layer. The method is to impregnate the porous layer with oil to form a lipophilic layer.Alternatively, the mesh-like uneven portion is uniformly covered with a ceramic layer, and oil is injected into the many pinholes of the ceramic layer. The point is to form a lipophilic layer by impregnating the

DESCRIPTION OF THE PREFERRED EMBODIMENTS The structure and operation of the present invention will be explained in detail below with reference to figures according to one specific embodiment.

FIG. 1 illustrates the basic form of an offset printing system in which a mesh roll 4 is arranged. The ink on the circumferential surface of the roll 4 is scraped off by the doctor blade 8, which contacts the surface at a position opposite to the direction of rotation (reverse angle), so that the ink adhering to the roll 4 is removed as shown in FIG. The ink is limited to a large number of minute indentations 9 having a size of, for example, 250 meshes, and the ink within the indentations thus limited is supplied to the plate cylinder 11 via the foam roll 10. Reference numeral 12 is a planket cylinder in contact with the plate cylinder, 13 is an impression cylinder, and 14 is a running paper for printing.

On the other hand, the printing cylinder 11 is provided with a wet roller 15.
The roll contacts the swinging roll 16, while the water 18 in the water reservoir 17 reaches the water source roller 1.
A small amount of water is taken out by a brush 20 installed at the blade 21, and the brush 20 supplies the water droplets onto the swinging roll 16 by the repulsive force of the brush 20 bent by the blade 21.

In such an offset printing mechanism, water supplied onto the surface of the plate cylinder 11 by the water applicator roll 15 is passed around to the mesh roll 4 via the foam roll 10.

The conventional mesh roll is plated uniformly with wear-resistant chrome, including the recesses 9 on its circumferential surface, to withstand frictional contact with the blade.

However, since chrome is a highly hydrophilic material, it absorbs water better than ink, so if a single drop of water adheres to the mesh roll surface, the ink will be repelled and the ink will not adhere properly, making it difficult to supply ink properly. Problems will arise.

Therefore, according to the first aspect of the present invention, a mesh-like uneven portion, that is, a recess 9 and a protruding surface 2 are provided on the circumferential surface of the steel roll 4.
After processing 2, chrome plating is applied uniformly to the surface of the uneven portion to form a chrome plating layer 23,
Furthermore, the surface layer is subjected to porous processing to make the plating surface porous.

For porous processing of the surface layer of chrome plating, mechanical processing called knurling type and electrolytic etching are well known, and these methods can be effectively used to form a porous layer 23 with fine pores in the surface layer.
a (see FIG. 4) is formed, and the porous layer is impregnated with oil.

Chromium is originally hydrophilic and non-oleophilic, but by processing the oil-containing porous layer 23a on its surface, it becomes lipophilic and blends well with ink.
Repel water.

If the protruding surface 22 of the roll 4 lacks smoothness due to porous processing, polishing the surface to make it smooth will allow close contact with the doctor blade 8 and ensure sufficient ink scraping.

In the second aspect of the present invention, after forming mesh-like uneven portions 9 and 22 on the circumferential surface of the steel roll 4, the surface of the uneven portions is uniformly coated with ceramic by plasma welding to form a ceramic layer 24. make.

As is well known, ceramic has numerous pinholes 24a, so it is treated with oil.

Ceramic is originally hard and has excellent abrasion resistance, so we took advantage of that advantage and impregnated the pinholes with oil to give it lipophilic properties, creating a base that is compatible with ink. Fouling is eliminated.

Since the protruding surface 22 of the roll 4 lacks smoothness, if the surface is well polished to ensure close contact with the doctor blade 8, the ink scraping effect will not be reduced at all.

Since the present invention has the above-described structure and operation, the present invention focuses on providing durability by utilizing chromium and ceramic, which have particularly excellent abrasion resistance, and processes the surface layer to make it porous. By oil-impregnating the roll, we succeeded in creating a highly lipophilic surface over the entire circumference of the roll, which completely repels water and allows for a smooth and sufficient supply of ink toward the plate cylinder. I started getting it.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing an example of an offset printing system using a mesh roll according to the present invention;
FIG. 2 is a partially enlarged view of the circumferential surface of the mesh roll according to the present invention, FIG. 3 is a further enlarged partially sectional view taken along the line 3-3 in FIG. FIG. 5 is a further enlarged partial sectional view of the surface layer portion in the second aspect of the present invention. 4... mesh roll, 8... reverse angle doctor blade, 9... dent, 22... protruding surface, 23... chrome plating layer, 23a... porous layer, 24... ceramic layer, 24a... countless pinholes.

Claims (1)

[Scope of Claims] 1. A mesh-like uneven portion processed on the peripheral surface of a steel roll, a chrome plating layer covering the uneven portion, and a porous layer formed on the surface layer of the chrome plating layer. A mesh roll for offset printing, comprising a lipophilic layer impregnated with oil, and a mesh roll for offset printing. 2. A mesh-like uneven part processed on the peripheral surface of a steel roll, a ceramic layer covering the uneven part, and an oleophilic layer in which many pinholes of the ceramic layer are impregnated with oil. Mesh roll for offset printing.