Technical analysis of commercial rotary presses
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Commercial printing is one of the topics that people talk about in recent years. Unlike newspapers, books, and some prints that meet special needs, the commercial printing market is mainly aimed at those who have higher requirements for printing quality and are increasingly adopting lightweight and diversified. Color printing products with flexible paper and binding methods, such as a large number of journals, newspaper inserts, luxury newspapers, magazine newspapers and more and more commercial promotional materials (such as direct mail brochures, shopping guides, supermarket promotional materials).
In order to meet the needs of this rapidly growing printing market, printing equipment manufacturers have developed commercial rotary printing equipment of various types and specifications, but the differences in structure, function and price of printing equipment from different manufacturers are bound to bring The application area is different from the market. Therefore, in the face of a variety of commercial rotary printing equipment produced by different manufacturers, how to choose from the perspective of equipment function and technology, and make reasonable investments to maximize the effectiveness of investment projects, it is necessary for printers to Right question. To this end, we make a technical analysis of investment commercial rotary presses from the technical perspective of equipment composition, performance and configuration, for the reference of printers.
Basic characteristics of commercial rotary machines
The most widely used ones are commercial web offset presses. Commercial web offset presses differ from sheetfed offset presses in that they must meet the requirements of large-volume printing in the shortest possible time, and must have online folding. Post-press processing. Therefore, compared with the sheet-fed offset printing machine, the commercial web offset printing machine has the outstanding features of fast printing speed and high production efficiency, and is more suitable for the fast printing needs of larger printing materials. On the other hand, commercial web offset presses, unlike news web offset presses, are characterized by higher print quality requirements, making commercial web offset presses more precise with tape tension control, more accurate automatic paper pick-up and More precise automatic register adjustment and other features. At the same time, commercial web offset presses generally require a drying and cooling system due to the type of paper and ink used and the characteristics of high speed, multi-color printing.
It can be seen that in order to better meet the printing needs of commercial prints, modern commercial web offset presses have a fast printing speed (generally printing speed of no less than 40,000 copies / hour), a wide range of paper applications (paper weight range up to 36g) /m2～130g/m2), good printing quality (printing up to 300 lines of printed matter), high production efficiency (use of various automatic control systems), good economic efficiency (printing, folding, cutting and integration) Salient features. In recent years, commercial rotary offset presses have also undergone tremendous changes.
In recent years, the trend of the trend of the commercial rotary equipment market has changed, the structure and arrangement of the printing drum, the change of the ink delivery system, the change of the water delivery system to the change of the folding device, the change of the tension control mode, the setting and control mode of the auxiliary device. Changes, and the increasing use of automated setting, inspection and operational control systems, each change enables commercial web offset presses with higher print quality, faster printing speed and efficiency, and easier use and operation. , gained a wider application market.
Commercial web offset presses are a type of web printing equipment that prints on the principle of lithographic printing and therefore has the basic features and composition of a lithographic web press. At the same time, in order to meet the special type of printed matter printing market for commercial prints, commercial web offset presses have their own unique features and functions.
Basic composition and performance
Similar to other types of web lithographic presses, the basic components of a commercial web offset press include a paper feeding device, a printing device, and a post-press folding device. Commercial rotary offset printing presses are generally equipped with drying and cooling in consideration of commercial printing characteristics. system.
The paper feeding device is mainly divided into two parts, a paper roll control system and a paper tape control system. The paper roll control system includes a paper holder that satisfies the paper roll installation adjustment requirements, an automatic paper take-up device that satisfies the non-stop paper change requirements of the printing machine, and a paper roll brake device that satisfies the paper belt tension generating device to control the tension of the paper strip. The tape control system includes a guiding system that guides the direction of the tape, the tape is reversed, the tape is translated, a tape tension control system that generates and controls the tension of the tape, an automatic register adjustment device that meets the printing accuracy requirements, and a reduced auxiliary time. An automatic paper-feeding system that reduces the labor intensity of workers.
The basic composition of the printing unit is set up following the basic principles of lithography, including printing cylinder components, inking components, and water delivery components. The arrangement of the printing cylinders is basically a unit type B-B pair rolling type of horizontal paper feeding. In order to meet the requirements of fast and simple clutch pressure, a pneumatic clutch press is usually used. The inking unit of a commercial web offset press uses more leveling rollers than the news web press to quickly mix the ink and has the ability to react quickly when the ink level is adjusted. A direct wetting system is widely used in its water delivery devices to ensure uniformity of the water film on the plates.
The post-press folding device is an essential standard for commercial web offset presses. The finished paper tape is subjected to various folding processes such as (longitudinal cutting), longitudinal folding, cross cutting, horizontal folding, and (longitudinal folding) to complete the post-printing work of the commercial printed matter. The use of the disc cutter in the slitting device depends on the relationship between the width of the strip and the size of the final print; the longitudinal fold triangle is an important device to ensure the accuracy and position of the longitudinal fold of the strip; the cross-cut serrated cutter will continue The printed paper strip is cut into a single sheet of paper of a certain width; the folding knife and the folding sheet on the folding cylinder complete the horizontal folding requirement of the printed matter. If it is necessary to complete the 16-open commercial print folding requirements, a folding device with a folding knife and a folding roller can also be used.
Drying and cooling units are an important part of commercial web offset presses. In the face of thermosetting inks used in commercial printing, high-speed multi-color printing equipment must be equipped with a drying system to solve the drying problem of ink on printed matter. The hot air drying method that is often used is to remove the volatile solvent on the surface of the printed matter at the fastest speed by the high-temperature hot air flow, so that the high-speed printed printed matter can be dried in the shortest time. The cooling system works with the drying system. The heated printed matter is easy to shrink and deform, the paper becomes brittle and affects the post-press processing, the cooling system can restore the characteristics of the printed matter, and the gloss, dimensional stability and post-processing characteristics of the printed matter are ensured.
New configuration and function
With the advancement of technology related to printing equipment and the increasing demand for the fast-growing commercial print market, the types and brands of new commercial web offset presses are also being born, and various commercial web offset presses are undergoing dramatic changes. . The use of new devices and changes in control methods have improved the printing function and quality control of printing equipment and become the highlight of commercial web offset presses.