JPH0818423B2 - Offset rotary press cylinder - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plate cylinder of an offset rotary press.

[0002]

2. Description of the Related Art A plate cylinder of a conventional offset rotary press has a C surface on its surface from the viewpoint of corrosion resistance, abrasion resistance, stain removability and the like.
After r plating, Rmax <1.0 μm by polishing
The one prepared by the above method or the one obtained by polishing the corrosion resistant material after overlay welding was used.

[0003]

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention
There are the following problems. As shown in FIG. 4, when printing is performed by mounting the plate 2 on the conventional plate cylinder 1, if there is a difference in circumferential length between the plate cylinder 1 and the mating blanket cylinder 3 that contacts and rotates by applying the printing pressure P. The tangential force F acts on the plate 2 mounted on the plate cylinder 1.

Therefore, due to this tangential force F, a minute slip corresponding to the above-mentioned circumferential length difference is generated between the plate 2 and the plate cylinder 1, and this slip is accumulated as the printing operation progresses, and the plate 2 and the plate A so-called misregistration trouble occurs in which the relative position of the cylinder 1 changes. Conventionally, as a measure for preventing this plate misalignment trouble, as shown in FIG. 5, a plastic sheet 4 called a lumirror is glued and inserted between the plate 2 and the plate cylinder 1, or a plate as shown in FIG. A method of strengthening the spring force of the fixed spring 5 has been used. However,
The method of inserting and gluing a plastic sheet is
It is inefficient, and even with the method of strengthening the plate fixing spring, it is necessary to increase the power for operating the spring and it is difficult to completely prevent the plate misalignment trouble.

An object of the present invention is to provide a plate cylinder which can easily prevent the above-mentioned plate misalignment trouble.

[0006]

[Means for Solving the Problems] Conventionally, after Cr-plating or corrosion-resistant steel has been welded by overlay welding, Rmax <1.
The surface roughness of the plate cylinder, which has been finished to about 0 μm, is adjusted to 1.0 μm ≦ Rmax ≦ 100 μm.

[0007]

[Function] The surface roughness of the plate cylinder is 1.0 μm ≦ Rmax ≦ 10
By setting the thickness to 0 μm, the coefficient of friction between the plate and the plate cylinder can be increased, and thereby, the plate misalignment trouble can be prevented.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to FIGS. In FIG. 1, reference numeral 1 denotes a plate cylinder main body, and usually mild steel is often used. 6 is a Cr plating layer, the surface of which has a surface roughness Rmax of 1 μm ≦ Rmax ≦ 100.
It is adjusted to μm.

FIG. 2 shows an experimental example of the surface difference Rmax of the plate cylinder and the plate shift amount δ after printing about 200,000 copies. The effectiveness of the present invention can be seen from this. In the figure, ↑ ○ ↓ is the variation range of the data depending on the experimental conditions. In addition, the mounting condition of the plate (human factor),
Due to differences in experimental conditions such as differences in operating conditions (printing pressure, bar pressure, etc.), the plate misalignment amount changes even with the same plate cylinder (Rmax). The range indicated by ↑ ○ ↓ in FIG. 2 represents the variation range of the misregistration amount. In addition, the plate misalignment amount varies depending on the plate bending state, the blanket tightening, the blanket sag amount, and the stain on the plate cylinder surface.

In FIG. 2, it is easily inferred that the larger Rmax is, the more excellent the effect of preventing the plate misregistration is. However, when Rmax> 100 μm, there arises a problem in the dimensional accuracy of the plate cylinder and the stain removing property. Rm
The upper limit of ax is Rmax ≦ 100 μm. Also, R
When max <1.0 μm, the effect of preventing plate misregistration is smaller than that of the conventional plate cylinder, so the lower limit is set to Rmax ≧ 1.0 μm.

Next, the experimental results of the device of the present invention will be described. After applying a hard Cr plating with a thickness of about 100 μm on the surface of the offset rotary printing press cylinder having a diameter D ≈ 350 mm and a length ≈ 1660 mm, a surface roughness adjustment process is performed to obtain a plate cylinder surface roughness Rmax ≈ 6.0 μm. Obtained. Printing was performed using this plate cylinder, and an experiment was conducted to investigate the amount of plate misalignment. In addition, the same experiment was performed for the conventional plate cylinders having the same size and shape, and the plate misalignment amounts of both were compared. The result is shown in FIG.

In FIG. 3, δa is the plate misregistration amount (mm) excluding the initial misregistration, and n is the number of print copies. The experiment was carried out by mounting four plates on each plate cylinder. ○ △ □ ◇ is data for four sheets mounted on the conventional plate cylinder, and ● ▲ ■ ◆ is data for four sheets mounted on the plate cylinder of the present invention. Due to slight differences in the plate mounting state and the like, the plate misalignment amount varies from plate to plate, but in the conventional product, plate misalignment occurs, and the result is that no plate misalignment occurs in all four plates of the present invention. Out.

From FIG. 3, it can be seen that the plate cylinder of the present invention has an extremely excellent effect of preventing plate misregistration.

[0014]

INDUSTRIAL APPLICABILITY The present invention relates to an offset rotary printing plate cylinder in which a plate is mounted and used, and the surface roughness Rmax of the plate cylinder.
By adjusting 1.0 μm ≦ Rmax ≦ 100 μm, it is possible to prevent the misregistration trouble.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration of an exemplary embodiment of the present invention.

FIG. 2 is a diagram showing the relationship between the surface roughness of Cr plating on the plate cylinder surface and the amount of plate misalignment.

FIG. 3 is a diagram showing a relationship between the plate misregistration amount δa and the number of print copies n according to the embodiment of the present invention.

FIG. 4 is a diagram for explaining problems and causes in a conventional device.

FIG. 5 is a diagram showing a conventional misregistration prevention technique.

FIG. 6 is a diagram showing another conventional technique for preventing misregistration.

[Explanation of symbols]

 1 Plate cylinder body 6 Cr plating layer Rmax Surface roughness

Claims (1)

[Claims] 1. An offset rotary printing plate cylinder in which a plate is mounted and used, wherein a surface roughness Rmax of the plate cylinder is adjusted to 1.0 μm ≦ Rmax ≦ 100 μm.