Discussion on magnetic printing process and machinery
4. Gravure printing process
gravure printing unit is different, and the operation process is also different. According to the form of printing materials, there are mainly sheet fed gravure printing machines and web gravure printing machines supplemented by plastic granulators heated by coal and natural gas. The basic characteristics of gravure printing process, sheet fed gravure printing process and web gravure printing process are briefly described below
(1) the basic characteristics of gravure printing process mainly include the following aspects
① gravure printing machine has no ink leveling and ink channeling mechanism. Some of the printing plate cylinders are directly immersed in the ink tank [Fig. 2-36 (a)], and some are indirectly coated on the printing plate through the ink feeding roller. 1. Inspection points before starting up: the surface of the printing plate cylinder [Fig. (b)], some spray the ink directly on the surface of the printing plate cylinder through the ink nozzle [Fig. (c)], and then the oil layer on the blank part of the cylinder surface is scraped by the ink scraper, and then the official impression can be made
② no pad is needed. The printing plate is made on the surface of a cylindrical gravure cylinder, and the circumference of the cylinder is the printing format of the printing plate. Imprint cylinder imprints on the plate cylinder to obtain prints that meet the quality
③ use the drying device to quickly volatilize and dry the graphic ink layer. This can make the ink layer on the printing sheet shiny and bright, and can prevent dirt
due to the characteristics of gravure printing process, its operation is simpler than that of convex printing by slowly unscrewing the oil delivery valve for experimental and lithographic printing
(2) sheet fed gravure printing process the printing process of sheet fed gravure printing is shown in figure 2-37. The single sheet printing materials are stacked on the stacking table 1 and automatically sent to the position of the paper laying table plate by the automatic feeding device; The impression cylinder 2 rotates around the printing material and contacts the plate cylinder 5 for impression; The printing material is dried by the drying device 3 and sent to the paper receiving table 4 for accumulation
(3) web gravure printing process web gravure rotary printing machine can print plastic film materials, as well as paper products, such as color packaging paper, facial paper, popsicle paper, candy paper, cigarette paper, and various commodity packaging materials. The rear of the printing unit is also equipped with waxing device, slitting device, composite device and winding linkage device. After printing, it is processed into the specified specifications and forms, and then sorted and collected, which is convenient for mechanical or automatic packaging
all combined gravure printing machines use drum type materials with impact and vibration
The printing process of the combined gravure rotary printing machine has the following characteristics① the distance between printing units is long, which is conducive to the drying of graphic ink layer, and the printing speed is also high
② there are many colors, and 1-6 colors on the front can be printed at one time; It can also print both the front side and the back side, which is convenient to operate
③ convenient alignment; It is convenient to correct the accuracy of image and text overprint between color plates, and it can be adjusted without stopping the machine
④ all the doctor blades adopt positive scraping, which is conducive to the improvement of product quality
⑤ equipped with photoelectric control device, which can ensure the chromatic accuracy
⑥ simple structure and stable operation
the combined gravure printing machine is composed of unwinding (feeding) device, tension control device, embossing (printing) device, ink supply device, alignment device, drying device, waxing device, cutting device and winding device. In the printing process, we often adjust the mutual cooperation between various parts to jointly complete the printing action of pictures and texts
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