SU81046A1 - Photomechanical method of obtaining an in-depth image on a forme shafts, for example, printing machines - Google Patents

Description

The known methods of transferring images to the forming shafts are based on the use of pigment, paper, glued to the surface of the shaft, and reproduction of the repetitive parts of the pattern for subsequent exposure to pigment paper is usually carried out using Multiplying -machine.

The disadvantages of such methods include the deformation of pigment paper during its soaking and the displacement of parts of the image. In addition, this method requires the use of complex multiplication machines for photographic reproduction of repetitive parts of the image.

In the described method, in order to eliminate inaccuracies of placing on the shaft separate parts of the image, repeated parts of the image are exposed to separate pieces of pigment paper mounted on the shaft according to the marking. For in-depth etching of the shaft surface, pattern templates with cutouts in the shape of the part of the image requiring repeated etching were used.

The implementation of this method of obtaining an in-depth image on a plate roller, for example, cotton matting machines in the textile industry, is as follows.

A negative 13X X 18 cm (one report) is removed from the color original (crown).

From the negative 1a received, little prints are made on the photo paper in an enlarged size. The number of prints corresponds to the number of colors in the picture. On these prints, a drawing is drawn out with black dullness for each paint separately, and those places where the drawing should be filled should be filled with a thin line with a contour. After drawing, the prints are etched with a Former's weakening agent (red salt 1 and hyposulfite are red). As a result, only a black-drawn drawing pattern remains on the paper.

No. 81.046..., 2 The originals thus obtained, separately for each paint, are removed negatives in a size corresponding to the size of the report on the shaft.

From these negatives, one slide is printed on a film on a film.

Pieces of pigment paper, corresponding in size to working slides, are sensitized in a solution of potassium dichromate, rolled onto α-glass and dried. The number of sheets of pigment paper corresponds to the number of reports on the roll for each ink.

Sensitized sheets of pigment paper along with working transparencies are embedded in photographic copying frames of size 30x40 cm or 40x50 cm and copying is made from transparencies. Pigment copies are emitted by ultraviolet rays emitted by PRK-2 or PRK-4.

Copying is done within 16-20 minutes, after which the next sheet of pigment paper is laid and again copied to the required number of copies corresponding to the number of reports on the shaft.

When the required number of copies on the pigment paper is ready, the copper shaft to be engraved is installed and the transfer machine and a line for marking each report onto its place are printed with a rand. When the shaft is lined, the pigment copies are alternately glued, each in its own place, respectively, pencil lines drawn on the shaft, which are also applied with a pencil on the back of each pigment copy.

After sticking pigment copies onto the shaft, they are moistened with hot water for 20-25 minutes, as a result, the paper is peeled off, and the gelatin layer remains on the shaft. After that, the shaft for 20-25 minutes. washed with warm water and gelatin in places that, when copied by ultraviolet rays, were protected by a pattern from the action of these rays, are partially washed away and in them when etched with ferric chloride, the necessary cavities are formed, in which ink accumulates during printing.

When executing the original report to be duplicated and transferred to the off-printing shaft, the borders of the report design were outlined with a black border 3–4 mm wide, so that the pigment paper gelatin in the area of the drawing was not duplicated and when transferring the reports to the copper shaft, the edges pasted to the shaft.

The shaft, after washing it in warm water, is moistened with a denatured alcohol or raw alcohol and dried.

After drying the shaft, the areas that cannot be etched are covered with a Syrian lacquer brush; then, the surface of the shaft, while rotating, is wetted with iron and etched to the desired depth.

After etching the shaft and obtaining the desired depth of the line of the solid-filled figure, it is necessary to deepen. For this purpose, the entire shaft is covered with asphalt varnish. Then a stencil is made of a thin copper plate with cutouts in the shape of the part of the image that requires recessing. This stencil is placed on the figures to be deepened, and with the aid of cotton moistened with gasoline or benzene, the asphalt varnish is removed (washed off) from the figures. Then, the shaft is subjected to a short (within 3-4 min) etching with ferric chloride, which results in a deepening of the figures with a solid fill.