JP2003089185A - Sheet-fed offset printer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sheet-fed offset printer capable of regulating in the printer without finely dimensional regulation on a plate material. SOLUTION: The sheet-fed offset printer of the type comprises a plurality of printing units each having a plate cylinder, a blanket cylinder and an impression cylinder, and a transfer cylinder for conveying a printing sheet between the units. In this printer, a diameter of each of the printing units when the plate of the plate cylinder is mounted in each unit is sequentially reduced in the moving direction of the printing sheet. In addition, a diameter of the unit when the blanket of the cylinder is mounted is sequentially increased in the moving direction of the sheet. The transfer sheet is used at the impression cylinder of an opposite side.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multicolor sheet-fed offset printing machine, and more particularly to a sheet-fed offset printing machine capable of preventing misregistration due to elongation of a printing sheet in a moving direction.

[0002]

2. Description of the Related Art Conventionally, in order to maintain the register accuracy due to the elongation of the paper in the sheet movement direction in sheet-fed offset printing, the elongation of the paper is taken into consideration at the stage of printing the net positives on the lithographic printing plate, and the printing order is followed First color plate, second color plate,
The length in the printing direction (circumferential direction) was gradually increased in the order of the third color plate, ..., And the final color plate.
This is a complicated task because it is necessary to check the printed item and the paper and change them individually.

[0003]

SUMMARY OF THE INVENTION In order to solve the above problems, the present invention provides a sheet-fed offset printing press that can be adjusted on the printing press without performing minute dimension adjustment on the plate material. Is an issue.

[0004]

According to a first aspect of the present invention, there is provided a multi-color sheet-fed offset printing press having a printing cylinder, a blanket cylinder, and an impression cylinder in each of a plurality of printing units. In a sheet-fed offset printing machine of a type in which a sheet is conveyed between units by a transfer cylinder, the diameter of the plate cylinders in the plurality of printing units when the plates are mounted is reduced sequentially in the moving direction of the printing paper. This is a sheet-fed offset printing machine. With such a configuration, it is not necessary to change the dimension between the color plates when the mesh positive is printed on the plate material, and complicated work can be avoided.

According to a second aspect of the present invention, there is provided a multi-color sheet-fed offset printing machine in which a plurality of printing units each include a plate cylinder, a blanket cylinder, and an impression cylinder, and a transfer cylinder is provided between the printing units. In a sheet-fed offset printing press of a type that conveys paper, a diameter of a plate cylinder in the plurality of printing units when the plates are mounted is sequentially reduced in a moving direction of the printing paper, and a blanket in the plurality of printing units. The sheet-fed offset printing machine is characterized in that the diameter of the cylinder when the blanket is mounted is sequentially increased in the moving direction of the printing paper. With such a configuration, it is not necessary to change the dimension between the color plates when the mesh positive is printed on the plate material, and complicated work can be avoided. Since the blanket cylinder and the plate cylinder are both used, the adjustment amount of the plate cylinder diameter can be increased.

According to a third aspect of the present invention, the sheet-fed offset printing machine according to the first or second aspect is characterized in that an impression cylinder of the opposite side printing unit is used as the transfer cylinder. With such a configuration, it is not necessary to change the dimension between the color plates when the mesh positive is printed on the plate material, and complicated work can be avoided. Also, since both sides can be printed at the same time, work efficiency is improved.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in detail below with reference to the drawings. FIG. 1 is a schematic explanatory view of a general sheet-fed offset printing machine 1 of the type embodying the present invention. The sheet-fed offset printing machine 1 includes a paper feed unit 2 and a plurality of printing units 5.
The printing unit 3 and the paper discharge unit 4 have (4 units in the figure). The printing unit 5 is basically composed of a plate cylinder 6, a blanket cylinder 7, and an impression cylinder 8, and the transfer cylinder 9 transfers the paper between the printing units.

FIG. 2 is an enlarged explanatory view of the portion of the printing unit 5. The plate cylinder 6 includes a dampening device 10 including a water boat, a water source roller, a metering roller, and a watering roller, and an ink roller 11 including a lateral swing roller and a rubber roller (the inking roller group at the tip thereof is omitted). Has a mechanism to contact. Further, the plate 13 is mounted on the plate cylinder 6. The plate 13 is attached by scissors with a spacer if necessary.
A blanket 14 is attached to the blanket cylinder 7. The blanket 14 is also fitted with a spacer if necessary. The spacer is not particularly limited, such as paper and plastic film, but a plastic sheet having solvent resistance and chemical resistance is preferable. The paper 12 is held by the impression cylinder 8 and passes between the blanket cylinder 7 and the impression cylinder 8, whereby the ink on the blanket is transferred to the paper. After that, the sheet is conveyed to the next printing unit by the transfer drum 9.

FIG. 3 is an explanatory view showing the construction of a plate cylinder and a blanket cylinder, which are essential parts of the present invention. P1 is the first color plate cylinder, P2 is the second color plate cylinder, P3 is the third color plate cylinder, P
Reference numeral 4 is a plate cylinder for the fourth color, B1 is a blanket cylinder for the first color, B2 is a blanket cylinder for the second color, B3 is a blanket cylinder for the third color, and B4 is a blanket cylinder for the fourth color. In FIG. 3, the blanket cylinders B1 to B4 all have the same diameter, but the plate cylinders P1 to P4 have P1> P2.
Adjust the extension of the paper as shown in>P3> P4. This is because, if the number of rotations is the same, the larger the diameter, the faster the peripheral speed, and therefore the pattern on the blanket cylinder becomes relatively small. Therefore, since the diameter of the plate cylinder is gradually reduced, the pattern becomes relatively large and the amount of elongation of the paper is adjusted.

In FIG. 4, the plate cylinders P1 to P4 have P1> P2.
>P3> P4, the diameter was successively decreased, and the blanket cylinders B1 to B4 were successively increased in diameter, such as B1 <B2 <B3 <B4. As a result, the adjustment width of the diameter can be made larger than that performed by the plate cylinder. The numerical value of the diameter difference is
Data is set and set according to the paper thickness and paper type.
The range of 10 micron meters to 100 micron meters is preferred. If it is smaller than 10 microns, it will have no effect,
If it exceeds 100 microns, adjustment becomes difficult.

Although a spacer or the like is used to keep the diameter difference between the plate cylinder and the blanket cylinder, it is also possible to make the diameter difference of the cylinder itself from the beginning.

[0012]

EXAMPLES Example 1 Using a sheet-fed offset printing machine as shown in FIG. 1, printing with four colors on one side was performed. As shown in FIG. 3, a polyethylene terephthalanol film was used as a spacer from the first color to the fourth color, and a diameter difference of 50 μm was provided for each spacer. Although the paper was easy to stretch in the vertical direction, it was possible to print with register accuracy within an allowable range.

Example 2 Printing was carried out on a double-sided sheet-fed offset printing machine of four colors on the front side and four colors on the back side as shown in FIG. As shown in FIG. 4, the diameter difference of the plate cylinder is set to 30 μm,
A blanket cylinder diameter difference of 30 microns was provided. It was possible to print within the permissible range in register accuracy without adjusting the dimensions on the plate material.

[0014]

According to the first aspect of the present invention, it is not necessary to change the size of each color plate when printing the mesh positive on the plate material, and the complicated work can be avoided.

According to the second aspect of the present invention, it is not necessary to change the size between the respective color plates when the net positive is printed on the plate material, and the complicated work can be avoided. Since the blanket cylinder and the plate cylinder are both used, the adjustment amount of the plate cylinder diameter can be increased.

According to the third aspect of the present invention, it is not necessary to change the dimension between the respective color plates when the net positive is printed on the plate material, and complicated work can be avoided. In addition, since printing can be performed on both sides simultaneously, printing efficiency is good.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing an example of a sheet-fed offset printing machine of a type embodying the present invention.

FIG. 2 is an enlarged explanatory view of a main part of FIG.

FIG. 3 is a partial explanatory diagram showing an embodiment of the present invention.

FIG. 4 is a partial explanatory view showing another embodiment of the present invention.

FIG. 5 is an explanatory diagram showing an example of a double-sided sheet-fed offset printing machine of the type embodying the present invention.

[Explanation of symbols]

1 ... Sheet offset printing machine 2 ... Paper feeding section 3 ... Printing section
4 ... Paper discharging unit 5 ... Printing unit 6, P1, P2, P
3, P4, ... plate cylinder 7, B1, B2, B3, B4 ... blanket cylinder 8 ... impression cylinder 9 ... transfer cylinder 10 ... dampening water device 11 ... ink roller 12 ... paper 13 ... plate 14
…blanket

Claims (3)

[Claims] 1. A multi-color sheet-fed offset printing press having a plate cylinder, a blanket cylinder, and an impression cylinder in each of a plurality of printing units, wherein a transfer cylinder conveys paper between the printing units. In the leaf offset printing machine, the diameter of the plate cylinder in the plurality of printing units when the plates are mounted is made smaller successively in the moving direction of the printing paper. 2. A multi-color sheet-fed offset printing machine having a plate cylinder, a blanket cylinder, and an impression cylinder in each of a plurality of printing units, and a type in which a transfer cylinder conveys paper between the printing units. In the leaf offset printing machine, when the plates of the plate cylinders in the plurality of printing units are sequentially reduced in diameter in the moving direction of the printing paper, and the blankets of the blanket cylinders in the plurality of printing units are installed. The sheet-fed offset printing machine, in which the diameter of the sheet is gradually increased in the moving direction of the printing paper. 3. The sheet-fed offset printing machine according to claim 1, wherein an impression cylinder of an opposite side printing unit is used as the transfer cylinder.