Technical status of the hottest offset press produ

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Introduction to the technical status, product functions and market applications of offset printing machine (III)

I. mechanical performance of offset printing machine

for the paper feeding part of modern high-speed sheet fed multicolor offset printing machine, it should not only ensure the stability and accuracy of paper feeding during high-speed printing, but also fully consider all kinds of factors, and only replace the sensor elements to adapt to different types and formats of printing materials

Komori's paper feeder adopts an eight suction nozzle design, which can stably transport 0.04~0.8mm thick paper, while the paperboard is still a step belt type, which is equipped with an integral movable paper feeding brush and paper wheel. This arrangement also has good adaptability to printing materials that are not very standardized or of poor quality

in order to ensure the accuracy of paper feeding and prevent paper feeding failure and paper waste, Komori adopts a combination of mechanical, photoelectric and inductive forms to control the skew, double sheet and empty sheet in the paper feeding process. Its paper delivery mechanism does not adopt the currently popular bottom swing type, but is still up swing type. At present, the printing machine speed can reach 15000 sheets/hour, and the paper delivery is stable and accurate. There is no saying that the paper feeding is unstable and the printing speed cannot go up. In addition, a paper feeding (forward paper) roller is also omitted. For the commonly used four-color printing, it only needs 8 times of paper handover to complete, of course, there is a further guarantee for the printing quality

in addition, the anti loose tail device installed on the oscillating paper delivery tooth shaft can compensate for the loose tail of the paper, which is of practical significance to domestic users

the arrangement of the rollers in the printing part is not important, because both the "seven" o'clock and "Five" o'clock layouts have their own strengths and weaknesses. From the actual effect, the machines with different arrangement have little difference in printing quality and machine operability. Moreover, there are both layouts in the product lines of some manufacturers

the advantages of double diameter impression cylinder and double diameter paper delivery cylinder in ensuring the quality of printing and expanding adaptability have been proved by practice. Komori sheet fed offset printing machine is also in this way, but the popular air cushion paper guide method is not used in the paper guide system, but the roll paper transfer roller with Anti Dirt cloth on it is used to ensure that the printed sheets are not scratched and scratched during the paper transfer process

Komori is currently the only manufacturer with two methods of front and back printing, that is, double-sided printing with flip and double-layer single-sided mouthpiece, and it is also the only manufacturer that commercially produces double-layer double-sided offset printing machines. This model is aimed at the printing market of color books and magazines. Since 1998, more than 40 sets of this model have been installed in the world

from the perspective of production and user use, the double-sided printing with overturning in these two double-sided printing methods has many times of paper handover, and the accumulation of mechanical wear errors caused by long-term use will affect the print quality and inconvenient to maintain. In addition, there are special requirements for the quick drying of the first four-color inks

the double-sided printing method of double-layer single mouthpiece, because it is to hold the paper on one side, and the transfer paper method of imprint to imprint is adopted, which can not only ensure the consistency of printing quality and registration accuracy on the back, but also solve the problems of rubbing dirt, mouthpiece, positive and negative registration faced by flip printing to a great extent. In addition to improving production efficiency, this single mouthing method has strong adaptability to the current domestic non-standard format paper

the tooth shaft, gripper structure and materials on the transfer paper drum play an important role in ensuring the registration accuracy, reducing the instability of ink color, the adaptability of printing materials and the durability of the printing machine. Komori adopts a large-diameter torsion bar tooth shaft to strengthen the strength, and the gripper tooth pad adjustment device can make a rapid response to thick and thin paper. Among them, the gripper tooth is coated with emery on carbon steel sheet, which can greatly enhance its durability

whether the ink delivery system of the printing part is a long ink path or a short ink path should be arranged for its own reasons. Komori adopts the long ink path method, which provides a uniform ink film for the layout by four plate leaning rollers and four ink channeling rollers with different diameters. Among them, the ink channeling roller is a copper roller, which has excellent ink transfer performance, good heat dissipation and easy cleaning

the water delivery system adopts the five roll continuous water supply design of reverse water transmission, which is characterized by providing stable, uniform and minimal fountain solution directly for the layout, and it can be used for alcohol free printing without changing the configuration

the purpose of various protective devices adopted by different manufacturers in the paper receiving part is to prevent scraping and scratching of prints and shorten the time-consuming of post press processes, such as the double anti deflection device and unwinder adopted by Komori (which can restore the downward paper edge to be flat), as well as the double paper receiving device that can automatically separate the problematic print sheets, etc

second, automatic control and other

for modern offset printing, its automatic program and printing monitoring ability are important signs of its progressiveness

for example, the automatic job preparation and preset function can quickly and accurately register and color match different substrate materials without relying on experience. Among them, there are two ways to adjust the diagonally of the printing plate, which are related to the structure and design of the machine itself, rather than the relevant information. Komori uses the axial deflection of the plate cylinder, because Komori's cylinder bearing is processed and installed by special materials and proprietary technology, which can adjust the deflection of ± 0.2mm, and at the same time avoid long-term damage to the accuracy of the cylinder

sheet fed multi-color offset printing machine has very high requirements for durability, because any small mechanical and electrical failure will interrupt printing and reduce production efficiency. Therefore, its overload ability and durability should be paid attention to

from the current situation, the structure and design of offset press are relatively mature. Common faults mostly occur in electrical control, but this was not the case 8~10 years ago. At that time, faults mostly occurred in machinery. Therefore, at present, all manufacturers have made great efforts in the stability and reliability of electrical control technology. At the same time, some technical characteristics and power utilization range of web offset press have been continuously expanded, and can be configured and applied to sheet fed offset press

Komori believes that the cognition of domestic offset press users on products is more focused on the adaptability of thick and thin paper, the stability and cost performance of offset press, the support of product sales and service, and the technological advancement of the product itself

this article is provided by Yasuo Morita, the technical director of Mitsubishi Heavy Industries.

I. Development of sheet fed offset press

after these years of rapid development, sheet fed offset press has been very mature in mechanical structure and performance, so that it is difficult to form a difference between the corresponding products of competitors. In order to win in the competition, Mitsubishi believes that the single sheet offset press must take the lead in the following three aspects, including the change of paper specification (i.e. wider flexibility), the fixture will automatically return to its original position after the sample is broken, higher printing quality, and improving economic benefits by reducing waste pages

only in this way can the sheet fed offset press survive in the gap between the future digital wave and the emphasis on mass production

the new diamond 3000 exhibited by Mitsubishi Heavy Industries in drupa 2000 is a single sheet offset press for future market demand based on the above principles

diamond 3000 can reflect Mitsubishi's pursuit of future sheet fed offset printing machine from five aspects

1. higher and more stable printing quality

the survival of the future sheet fed offset press is to produce high-quality prints at the highest speed and stably as possible

2. Thick and thin, increase flexibility

flexibility is one of the greatest advantages of sheet fed offset printing machine, including being able to print all kinds of paper, paperboard and other types of substrate materials, so as to meet the thirst of many printing plants for multiple functions of one machine in the face of diversified market demand

3. reduce the quasi stop time and waste pages, and improve production efficiency

in the face of the impact of digitization and the frequent replacement of job content caused by the more diversified demand changes in the print market, the sheet fed offset press only has a breakthrough in the level of automatic control and intelligent printing control. By shortening the quasi stop time and reducing waste pages, users can challenge higher production efficiency

4. compatible with all digital processes

how to maximize the "accuracy" advantage of digital data and make the offset press truly integrate into the pre press and post press processes is the mission of modern offset presses

5. Emphasize ergonomics and the surrounding environment

considering the safety of machinery and its impact on the environment is the requirement of today's whole society. As an offset press production enterprise, it is of course incumbent. Such efforts include improving the convenience of operation and maintenance, realizing self diagnosis and prompt of faults, improving the appearance of offset press, and so on

second, double-sided printing and mainframe

in the R & D and production of double-sided flip multi-color offset printing machine, Mitsubishi directly adopts the popular drum arrangement of "seven o'clock", as well as the double diameter embossing drum and the unique ink roller using ink transfer simulation technology. The turnover device adopts a three drum device, in which the paper storage drum is a double diameter drum, which can increase the stability of the paper turnover process and reduce the tearing of flip printing The possibility of getting dirty

for large-scale sheet fed multi-color offset printing machines, Mitsubishi believes that from the current situation and development trend of the market, the demand for large-scale offset printing machines exists for a long time, because some customers want to improve production efficiency by printing multiple sides or multiple posts at the same time

the 6F extra large full sheet offset press launched by Mitsubishi in drupa 2000 is designed to comply with the market development, with a format of 1440mm × 1040mm, while the printing speed reaches 14000 sheets/hour

source: I love printing

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