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HISTORY OF TECHNOLOGY, TECHNOLOGY, OBJECTS AROUND US
Typewriter. History of invention and production
Directory / The history of technology, technology, objects around us Printing machine - printing equipment designed for printing images on various materials. Printing machines are divided according to the method of printing. Among them are offset, flexographic, screen printing machines, letterpress and gravure printing machines. According to the method of supplying the printed material, printing machines are divided into sheet-fed and roll-fed. As a rule, the German Johannes Gutenberg is called the first printer. Although there is evidence that back in 1045, the Chinese Pi Chen, a member of the imperial court, came up with a collapsible type. Even earlier, in the XNUMXth century in the east - in China, Tibet - a method of printing from wooden boards was known, on which whole pages of the manuscript were engraved. This method in Europe was called "xylography". A student at the University of Strasbourg, Johannes Gutenberg, together with several companions, took up the production of woodcut books. He came up with the idea to engrave not whole pages at once, from each of which it was possible to take very few high-quality prints, but to make individual letters and then from them, as if from cubes, add lines. He came up with the following method of making a font: first, on the end of a metal bar - a punch - they engraved the reverse convex image of the letter, then they knocked it out on a soft copper plate. Then this plate - the matrix - was inserted into the lower part of the hollow tube, and a special alloy was poured through the open top, which later became known as the hart.
As a result, it was possible to make any number of exact copies of the punch - letters. And from the letters, a book was already typed line by line. Only in the fifth decade of his life, Gutenberg managed to produce the required number of letters - the first type-setting cash desk and make a printing press.
The method of obtaining impressions using such forms is called letterpress printing. It is not difficult to make such forms. After all, it is enough just to get prints from them. To do this, you need to apply an even thin layer of ink on the printing elements and press them onto the paper. Letterpress is favorably distinguished by undemanding to paint. It can be of almost any chemical composition: both on a fat basis and on the basis of aqueous and alcohol solvents. Later, a different kind of high-tech printing was invented - flexographic printing. Here, rubber or polymer printing plates are used. With their help, good prints are achieved not only on paper, but also on other materials, such as aluminum foil, cellophane, corrugated cardboard. Over time, naturally, the requirements for print quality also grew. There was a need to reproduce halftone images of the entire color gamut on paper. The solution came with the invention of gravure printing. With this method, the printing elements are made not higher, but lower than the space ones, and their depth is different. The darker this or that area of the print should be, the deeper the corresponding element of the printed form, the thicker the layer of ink filling it and the more it will pass from the form to the print. There are two types of printing presses in use today: sheet-fed and offset. In a sheetfed printing press, the thaler, on which the printing plate is fixed, moves back and forth continuously. At the same time, the ink roller is lowered and rolled over the mold and smeared with paint. A large printing cylinder rotates above the thaler. As he descends, he presses a clean sheet of paper against the form, on which an imprint of text and drawings remains.
The sheetfed printing machine does everything on its own. The master only presses the switch button. Feeders installed on the machine - grippers with rubber suction cups themselves take only one sheet from the top of the stack of paper and carefully place it on the taler. And other feeders press the printed sheet and also carefully place it on the receiving table. The machine itself monitors whether it works correctly. As soon as the suckers mistakenly grab not one sheet, but two from the foot, the machine immediately stops. An example is Heidelberg's "Speedmaster SM 102" sheetfed printing press for printing commercial products, labels, film and other packaging materials. By equipping this machine with the appropriate options, you can print labels on extra thin paper. They used about two thousand new components and parts. The company's engineers received more than forty patents for inventions made during the design study.
During the research phase of the work, marketing research was carried out to identify the needs of users. The results showed that most professional printers and print centers use 70x100 cm sheetfed offset presses. Therefore, the company's specialists have focused their efforts on improving the performance of this particular class of machines. They managed to achieve a productivity of 15000 impressions per hour. The high productivity of new printing machines is largely determined by the operating speed. Particular attention has been paid to reducing the time to prepare for printing and maintenance of the machine. The "Speedmaster SM 102" uses a new generation of feeders. These feeders are equipped with extended guides for feeding individual sheets over the front stops onto the feed table. Sheets are braked directly in front of the front stops to a speed of 25 percent of machine speed, allowing for precise alignment of even light weight sheets at high speeds. The stack lift is automatically adjusted according to the thickness of the paper. The suction cups of the vacuum head are pre-set according to a certain curve depending on the properties of the printed material, which ensures high productivity. Stability of paper feeding is achieved due to the small stroke of the swinging suction cups. Transparent fencing helps reduce noise levels. Equipping the feeder with a sheet-cutting device is an alternative to a conventional sheet stacker, which makes it possible to reduce the cost of the printed material. Currently, offset printing is the most common method of printing. It is notable for its wide possibilities of artistic design of the publication, the comparative cheapness of printing plates, a rather high printing speed, and a number of other positive qualities. According to many experts, in the near future the classic offset printing method will continue to dominate the world practice. Offset presses are much faster than conventional flatbed printing presses. Inside such a machine, another printing cylinder rotates - offset, covered with rubber. It runs through the form before the paper sheet. The imprint of the font and illustrations is first transferred to this rubber, and already from it to a paper sheet. In such machines, there are usually several sections, which are filled with various paints. The paper sheet alternately passes through all sections, and either a multi-colored font or a color picture appears on it. The sheet-fed printing machine produces up to 15 prints per hour. Offset - tens of thousands. But printers who publish newspapers and magazines are not satisfied with this speed. Rotary printing machines provide higher speed. The first such machine was developed in 1904 by the German engineer E. Mertenson. In a rotary printing press, all the main parts are cylindrical. This simplifies the design of the device and allows you to significantly increase the speed of printing. Such a machine is filled with paper tape 6-7 kilometers long, wound into a huge roll. The rotary machine works at great speed. The paper tape runs with the speed of a train under the revolving shafts with stereotypes, over which the paint rollers have already rolled with the same speed. First, one side of a newspaper or magazine sheet is printed on paper, and then the other. The machine itself cuts the printed sheets, folds (bends), throws the finished packs on the conveyor itself.
The most modern and efficient rotary machine is Ecoman by MAN Roland. One of the most important advantages of this machine is the wide possibilities of varying its layout. With its flexible build, this machine can efficiently produce virtually any newspaper product. The eight-tier arrangement of printing units is an integral part of the Ecoman system. This construction, combined with the double folder, makes the machine ideal for high-volume printing. For commercial printing, the machine can be equipped with an IR dryer or a hot air dryer. The design of the paper guiding system provides a constant tension of the paper web. For high-quality four-color printing, an additional automatic device for monitoring and adjusting the tension of the paper web is used. Paper web guiding can be selected with left or right direction. This allows you to optimize the path of the paper web. For double-sided sealing of two sheets in one color, it is equipped with two tape guide systems. The Ecoman machine is equipped as standard with a roll charger, which is distinguished by its simple design and reliable operation. Compact film inking unit provides fast ink change, easy maintenance, high print quality. For better cleaning of the ink box, it is divided into two or four folding parts. In the "Ekoman" machine, a spray-type dampening apparatus is used, in which the transfer roller is located between the knurling roller and the grinding cylinder of the dampening apparatus. In "Ekoman" all units of the machine (roll charging, printing sections, folding machine) are combined into a common control system - PECOM, which performs centralized processing of signals from actuators, after which it issues appropriate commands. The control system makes it possible to use the TPP technical product planning station for order processing. This station prepares for the printing process, from processing information about the nature of the product, the plan for loading the machine, and ending with the submission of the necessary commands to the actuators. Not so long ago, printing machines were only good for reproducing the same image over and over again. With the invention of digital printing, the situation has changed. A digital printing machine is computer-controlled and similar in principle to a laser printer. With the help of a computer, it is possible to quickly make changes to the printing plate after each rotation of the plate cylinder and get different copies of the prints at the output to one degree or another. The digital method is used mainly for printing small runs (even one copy) or for operational printing. Author: Musskiy S.A.
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