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The printing press is divided into letterpress, lithographic, gravure, and stencil printing presses according to the form of the printing plate; the press-fitting and embossing structure is divided into the flat-pressing, round-pressing, and round-pressing circular printing presses.
The letterpress printing press is the oldest printing press. Its graphic part of the printing plate is convex and the blank part is concave. When the machine is working, the roller coated with ink rolls over the surface of the printing plate. The raised graphic part is covered with a uniform layer of ink, while the concave blank part is free of ink. The pressure mechanism transfers ink to the surface of the print to obtain a clear print and reproduce the desired print.
There are three types of letterpress printing presses: flat press, round press and round press. Flat Press Flat Press, also known as flat press. The plate table and the imprinting mechanism of the device printing plate are all in a planar shape. When the working plate is in full contact with the platen, the total pressure of the machine at one time is relatively large, and the relative imprinting time is longer. This type of printing press requires that the printing plate and the imprinting plate be flat and the printing format is not large. The round-pressing letterpress printing machine is also called a platen printing press. It has a plate-shaped printing plate, and the embossing mechanism is a circular roller. . When the machine is working, the platen moves back and forth, and the printing speed is subject to certain restrictions, so the output is not high. The rotary press is also called a rotary printing press, and the printing plate and printing mechanism are circular rollers. When the machine is in operation, the impression cylinder moves with the print and comes into contact with the plate cylinder. The impression cylinder and plate cylinder continuously rotate at high speed, so the productivity is high.
The graphic part and the blank part of the plate surface of the lithographic printing plate are almost on the same plane. It uses the principle of water and oil repulsion to make the graphic part resistant to water and oleophilic. The blank part is resistant to oil and water and does not touch the ink. Under the effect of pressure, the ink in the ink part is transferred to the surface of the printed Material, thus completing the printing process.
After the indirect printing method, the lithographic printing press has developed rapidly, with many varieties, such as office-use micro-offset printing presses, large-scale, multi-colored, high-speed newspapers and magazines offset printing transfer machines, for flat sheet or web, Single-sided or double-sided lithographic printing presses. Among them, monochrome offset presses and web offset presses are representative. Lithographic printing presses have been widely used electronic computer control devices, the technology is increasingly advanced. Platemaking equipment has also been developed to use electronic color separation machines and widely used pre-coated printing plates.
The main feature of the gravure printing machine is that the graphic part of the printing plate is concave and the blank part is convex, which is exactly the opposite of the layout structure of the letterpress printing machine. When the machine prints a single color, the printing plate is first immersed in the ink tank and the entire surface of the printing plate is covered with an ink layer. Then, the ink layer on the surface of the printing plate which is a blank portion is scraped off, the convex portion forms a blank, and the concave portion is filled with ink, and the deeper the concave portion, the thicker the ink layer. The machine transfers the ink of the recessed portion to the print by pressure to obtain the print.
For multi-color printing, overprinting method or indirect local ink painting method is used to make the inks of various colors distributed on the relevant parts of the printing plate surface according to requirements. The basic printing principle of multi-color printing is the same as the printing monochrome. There are mainly two kinds of printing plates used in gravure printing machines, one is a photogravure, which is a shadow edition; the other is an engraving version. Engraving engraving includes manual engraving, mechanical engraving, and electronic engraving.
The screen printing machine is a representative printing device in a stencil printing machine. Its printing plate is a screen with criss-crossing and longitude and weft woven by silk and other materials. Has been produced in plane, curved surface, forming, printing and dyeing, printed circuit and a new type of rotating screen printing machine. Among them, the speed and productivity of the new rotary screen printing machine are relatively high. Its characteristic is that the screen is installed on the drum, and the ink is poured in the drum. The drum rotates while the machine is working, and the squeegee quickly prints the pattern on the print.
In addition to silk, the material used to make screens can also be nylon, copper, steel or stainless steel. The principle of stencil printing for screen printing applications originated from ancient stencil printing. The stencil printing has a variety of forms, such as stencil printing, stencil printing, and screen printing.
Screen printing was initially manual, when there was only one plate, a screen plate, and a stencil. By the 1950s, screen printing was only mechanized and automated. Roller screen printers have a large amount of ink when printing, suitable for printing thick printed materials, and can be printed on a variety of paper, glass, wood, metal, ceramic, plastic or cloth, and can be used in a variety of inks, including conductive Metallic ink.
Modern printing machinery is further developing toward high speed, high efficiency and high quality. Large-scale, multi-color, multi-function, and automation, linkage, and serialization of models and models are also increasing.
For example, on the basis of the existing main types, uniting the same type of units can make single-sided and single-color printing into single-sided and multi-color printing, and can also double-sided and monochrome printing into single-side and double-color printing. Printing; Combining different types of units, you can reassemble them into offset printing, gravure printing, embossing, and other combined printing machines.
Components of modern printing presses
Modern printing presses are generally composed of plates, inks, embossings, and paper feeders. When it is working, it first prints the words and images to be printed onto the printing press, and then manually or by the printing machine coats the ink on the place where the printing plate has text and images, and then directly or indirectly Printed on paper or other substrates to reproduce the same print as the plate.