RU2584525C1 - Method of feeding wetting solution on printed-circuit and device therefor - Google Patents

Abstract

FIELD: printing industry.

SUBSTANCE: invention relates to printing industry, particularly moisturising apparatuses of offset printing machines. Disclosed is method of feeding wetting solution on offset printing plate by application to shape of knurling roller of moisturizing solution in form of thin layer with constant thickness. Layer of moisturising solution of non-uniform thickness is formed with due allowance for offset printing plate topology by feeding group comprising jet modules arranged in row above contact zone of dosing and rolling rolls, and their number is determined by length of printed contact zone with due allowance for maximum format of printed product that is followed by its supply to shape by knurling roller.

EFFECT: proposed method of feeding moisturizing solution allows avoiding excessive moisture, which increases quality of printed product.

2 cl, 1 dwg

Description

The invention relates to printing, in particular moisturizing apparatus of offset printing machines.

The method of offset flat printing is based on the stable wetting of the blank areas of the offset printing form by applying a moisturizing solution to it, which allows you to separate the printing and blank elements on a flat offset form. The quality of the offset printing process is determined by the steady wetting of the blank elements of the printed form with a moisturizing solution, and of the printing ones with ink. In order to organize a stable printing process, the humidifying device carries out the application of a moisturizing solution in the form of a thin layer of uniform thickness onto the offset form using a knurled roller. This helps to enhance the contrast of the hydrophilic properties of the blank elements of the offset printing form, ensuring their stable wetting. The layer of the moisturizing solution should be uniform and of a minimum thickness, the value of which should not exceed 2 microns.

Excessive supply of a moisturizing solution causes negative consequences during the printing process, such as a change in the optical characteristics of offset inks due to increased emulsification, a decrease in the speed of their curing, and an increase in paper deformation, which leads to non-registering of colorful images on the print.

A disadvantage of the known method of supplying a fountain solution is the application of a uniform layer of fountain solution on the entire surface of the offset printing form, which covers both white space and printing elements of the form. The supply of a continuous layer of the solution leads to excessive application to the form without taking into account the location of the printing and blank elements on it, which causes a violation of the printing process.

By its construction, the humidifier is a miniature colorful apparatus. However, in the colorful apparatus, in contrast to the moisturizing apparatus, the paint is selectively applied to the form by knurling rollers, in the form of a colorful layer of uneven thickness, due to local adjustment of its supply to individual areas of the printing form. The size of the adjustable ink supply zone is selected from design considerations in the range of 30-40 mm. A similar solution is proposed in this technical solution, when the width of the zone of local supply of the moisturizing solution with the jet module is selected within 30-40 mm. In this case, the amount of ink removed from each zone by the duct cylinder and the amount of dampening solution in it is determined by the presence of printing and white space elements in these zones. At 100% filling of any zone of the offset form with printing elements, the amount of ink in it should be maximum, and the amount of moisturizing solution should be practically equal to zero. With a minimum number of printing elements in the area, respectively, the amount of ink should be minimal, and the amount of moisturizing solution should be maximum. The physical arrangement of the number of white space and printing elements on the surface of the printing form is characterized by its topology. However, the existing method for supplying a fountain solution does not provide for adjusting the local supply of fountain solution according to the topology of the offset printing plate. The application of a moisturizing solution on an offset printing form in the form of a continuous thin layer of constant thickness without taking into account local adjustment of its supply causes an excess amount of solution on the form, which is a disadvantage of the known wetting method [1].

In the proposed method for supplying a moisturizing solution to an offset printing form, a selective supply of a moisturizing solution is organized according to its local adjustment by analogy with the zonal ink supply. For this, a layer of a moisturizing solution of uneven thickness is preliminarily formed taking into account the topology of the offset form, after which it is applied by a roller to the offset printing form.

The proposed method of supplying a moisturizing solution in the form of a thin layer of variable thickness, taking into account the topology of the offset printing form, will avoid its excessive wetting, which will improve the quality of the printed product.

A device for implementing a method of supplying a moisturizing solution to an offset printing form relates to printing, in particular to offset printing equipment. It is a humidifying apparatus, which is the main functional device of an offset flat printing apparatus. It consists of a feeding group and a system of rollers designed to transfer and roll the solution onto the mold [2].

A disadvantage of the known moisturizing apparatus is the lack of local adjustment of the supply of the moisturizing solution to the form depending on its topology, which causes its overmoistening, which affects the quality of the printing process.

The drawing shows a diagram of the offset printing apparatus and the main components of the humidification device: 1 - form, 2 - offset and 3 - printing cylinders, 4 - ink unit, as well as the main nodes of the proposed humidifier in the form of 5, 6 - knurling and metering rollers and 7 - a feeding group in the form of a series of inkjet models.

The operation of the feeder humidifier is as follows. In the process of printing of printed products, the supply group 7 in the form of a series of inkjet modules, according to the software, carries out a continuous selective supply of the amount of moisturizing solution through the nozzles of the inkjet modules into the contact zone of the rolling 5 and metering 6 rollers. The width of the humidifier supply zone of each inkjet module corresponds to the width of the local ink supply adjustment. The size of this zone is determined at the prepress stage in the process of manufacturing an offset printing form using the CtP system, which analyzes the number of printing and blank elements on the entire surface of the printing form, after which an estimate of their number for each zone is given. This allows you to prepare appropriate programs for the automatic maintenance and regulation of local supply of the required optimal amount of both ink and a dampening solution for each zone of the printing form, which is necessary for stable printing of circulation products.

After adjusting the operation of the inkjet modules, according to the software, the humidifying solution is supplied with nozzles of the inkjet modules, each of which supplies the calculated optimal amount of the humidifying solution for each zone. The supply is carried out in the contact zone of the metering and rolling rollers, after which the moisturizing solution is transferred in the direction of rotation of the rolling roller 5 to the offset printing form installed on the plate cylinder 1. After applying paint to the form, it is transferred by the offset cylinder 2 to the printing material mounted on the printing cylinder 3. The number of inkjet modules is determined by the format of the printed matter. At maximum, only the number of modules that matches the format of the printed products.

The proposed technical solution allows you to organize the optimal supply of the required amount of fountain solution for each zone of the printing form, as well as the ability to control its supply during the printing process, which will significantly improve the quality of printing.

Claims (2)

1. The method of supplying a fountain solution to an offset printing form by applying a fountain solution of a fountain solution to the form in the form of a thin layer of constant thickness, characterized in that a fountain solution layer of uneven thickness is formed taking into account the topology of the offset printing form by means of a feed group containing inkjet modules placed in a row above the contact zone of the metering and rolling rollers, and their number is determined by the length of the printed contact zone, taking into account the maximum format of the printed matter, after it performed its supply to the form roller form. 2. A device for supplying a moisturizing solution to an offset printing form containing a feeding group, as well as a metering and rolling rollers, characterized in that the feeding group contains inkjet modules located above the contact zone of the metering and rolling rollers to form a layer of moisturizing solution of uneven thickness, while inkjet modules are arranged in a row along the contact zone of the metering and rolling rollers, and their number is determined by the length of the printed contact zone, taking into account the maximum format of the printed matter.

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