Development trend of web offset press
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In order to improve printing efficiency, more and more web offset presses are used. In recent years, web offset presses have greatly improved in terms of printing speed, quality, and automation. Shaftless drives and seamless rollers are the most compelling technologies. How do printing companies choose machines according to their own needs, how equipment suppliers can improve and develop their own web offset presses to better meet market demand, and should always pay attention to the development trends and trends of web offset presses.
Although there are many types of web offset presses, the development of various web offset presses has its own characteristics, but it still has common features. The basic direction is to develop into multi-color and high efficiency. "Multi-color" is mainly to develop a multi-color machine that can print multiple colors in one pass. “Efficient” is to continuously improve efficiency and quality under the premise of ensuring quality and environmental protection. Efficiently, it mainly includes three aspects: increasing printing speed, improving automation and reliability, reducing auxiliary time and downtime, and increasing functionality. Offset presses have developed greatly in all three areas. Specifically, its development trends are mainly:
First, to the development of high speed and wide
An important aspect of web offset presses to increase efficiency is to increase printing speed and increase web width. At present, the speed of the web offset press has reached 15m/s, and the paper width has appeared three widths. Due to the high timeliness requirements of newspapers, the web roll offset press for news first requires high speed and determines the width of the paper according to the amount of printing. Small and medium-sized machines mostly use single-size paper, large-format web offset presses, mostly double-sized double-diameter rollers, and four separate newspapers per turn. More than 160,000 copies of the newspaper can be printed per hour. Three news machines with wide-bore rollers have now appeared. In recent years, the double-small roller news web offset press has appeared. Due to the increased rotational speed of the drum, more than 160,000 open newspapers can be printed per hour. And more flexible, you can save the plate. In order to ensure the quality of printing, commercial and book web offset presses have mostly used single or half-size small and medium-sized machines. Due to advances in technology, the problem of printing quality control has been completely solved. At present, commercial and book machines have a tendency to develop in single and single frames. Currently, there are 1.5, double or even three wide machines. Printing speed is also increasing. The web speed of the small roller web offset press has reached 100,000 revolutions per hour. In the case of ensuring the quality of printing, the pursuit of high speed is the basic direction of the development of web offset presses.
Second, to the development of precision, automation and intelligence
The latest high-tech technologies such as computer technology, microelectronics technology, optical fiber communication technology, and network technology are all applied to web offset presses. It not only completely solves the tension control problem, the overprint problem, the ink control problem, but also has a color management system, CIP3 or CIP4 interface. In order to meet the requirements of high speed and high quality, the accuracy of the machine is generally improved. In order to adapt to the trend of reducing the number of printed materials, increasing the degree of automation and reducing the auxiliary time is the most important issue.
Therefore, according to the needs of users, the web offset press can be equipped with automatic paper picking system, semi-automatic or automatic plate changing system, automatic fault diagnosis and display system for machines, remote diagnosis and adjustment system, fully automatic folding machine, and even direct Equipped with post-printing equipment. In order to ensure the color tone of the print and reduce the adjustment of the color tone time, the closed loop color control system is eye-catching.
In the printing process, the system continuously detects the color control strip on the printed matter, compares the detection result with the standard density value, and changes the difference between the two into a corrected ink key value to the ink control system, and performs the ink key on the ink key. Adjust so that the tonal value of the print is automatically kept within the range of the standard value. Some news roll paper offset presses have completely realized paper picking, paper loading, machine automatic plate changing, automatic paper changing, automatic printing control to post-press sorting, inserting, packaging, printing customer address, automatic Full automation such as transportation. Thanks to the improvement of automation, intelligent control, machine precision and stability, and reliability, the auxiliary time and stoppage rate are greatly reduced, and the web offset press is more suitable for the short-term, high-quality, short-cycle development of the printing market. demand.
The shaftless transmission is the latest technology in the 1990s. Because it can achieve higher synchronous operation accuracy than traditional mechanical transmission, the lubrication part is reduced, which is beneficial to maintenance, and the unit can be easily deactivated. Applicable on web offset presses, with the cost reduction of dedicated motors and control systems, the shaftless drive that maintains consistent print quality under high-speed operating conditions will become standard.
Third, to standardization, modular development
The main structure and components of the web offset press are designed into standardized modules according to different cutting size requirements. On the one hand, it can organize specialized production, stabilize and improve quality, and more importantly, according to the requirements of the market and users, adopt different arrangement and combination, and timely combine into different types of machines to meet the requirements of the market and users. If necessary, you can also add color groups to the user's machine to modify the machine. It is also possible to supply some standard modules directly to the market. Such as various automatic paper machine, drying box, cooling roller, silicon adding device, sheet cutting machine, sheet closing machine, tension change feedback control system, shaftless transmission control system, etc. can be directly purchased in the market.
Fourth, the development of multi-functional direction
The development of multi-functional directions and the expansion of the use and function of web offset presses are another significant feature. There are:
1. Multi-unit and multi-paper path: With multiple units and multiple paper paths, one machine can print multiple paper strips at the same time, greatly improving efficiency.
2. Direct lithography: Direct lithography is used to change the number of colors printed on each side of each tape, and prints of multiple colors are printed with fewer printing units. If you use a two-color machine, you can print one-sided four-color and one-color monochrome on the other side of the three-color print.
3. Multi-function folding machine: It can be a single triangle plate or a double triangle plate. It can be posted in one direction or in two directions. It can be a commonly used eight-, six-, and thirty-two open folding machine, or a folding machine with only one or two types. Add the pre-folding device before the paper tape enters the folding machine, realize the special edition of the book and the product samples and promotional materials of different folding requirements, and even punch holes, open windows, etc. on the publicity materials, samples, envelopes, etc. according to user requirements. .
4. Online matching equipment: online matching pager, baler, bookbinding mechanism and three-sided cutting machine, rewinding device, die-cutting, inkjet printing, glazing, humidification, glue, punching, marking, etc. Device, etc. Adding glue at the crease can stick the signature at the same time as the folding, and then cut it on the three-sided cutting machine, which can be directly listed. Significantly shorten the publishing cycle. Newspaper printing can also be equipped with automatic sorting, stacking, inserting, packaging, printing customer address, sending and other devices according to different customer requirements and uses.
5. Cut sheet: use a sheet-cutting machine to cut the printed paper into a single sheet of paper. If it is a poster or advertisement, it can be used directly. If you need to fold the sheet, you can use a sheetfed folding machine or Manually fold into the required copy, or for other processing and special purposes.
6. Variable size printing: For a long time, the printing size of web offset presses cannot be changed. Due to the development of shaftless drives, printing cylinders and ink systems can be driven by separate servo motors, so they can be fixed according to printing size requirements. Change the diameter of the drum within the range (usually replace the different roller sleeves), and adjust the position of the ink roller with the eccentric sleeve to meet the requirements of the printing size change.
7. Multi-functional combination machine: a combination of multiple printing methods and post-press functions. Various printing methods include: offset printing, flexo printing, gravure printing, gravure printing, silk screen printing, digital printing, and the like. Post-press processing functions include bronzing, lamination, die cutting, embossing, folding, cutting and drying. The multi-function rotary press can simultaneously combine the above functions into one printing production line to form a multi-functional production capacity, so that the product can be completed at one time, which can not only improve production efficiency, but also reduce waste while achieving the best printing effect.
Adding an inkjet printing system to a conventional web offset press allows for personalized printing or different text printing, such as printing the orderer's name, address, or printing instructions in different languages. It is also possible to replace the inkjet printing system with two printing units (positions can be determined as needed), or two plate cylinder units (such as a Y-shaped unit), one printing unit (roller) for normal printing, and another unit (Roller) Replace the plate (or in the mechanism version), when the first printing unit (roller) is printed, without stopping, just press the first printing unit (roller) and the other printing unit (roller) By pressing, you can smoothly convert from one type of text to another, so that long-lived printing (without changing the printing plate) and short-run printing (changing the printing plate at any time) can be realized. The flexibility and utilization of the machine, and greatly reduced the scrap rate of the stop plate change.
Five, digital web offset press
In recent years, digital printing technology has developed rapidly due to the development of computer technology, digital technology, and computer direct plate making technology (CTP).
Digital web offset presses are one of the important development directions. Manroland's launch of the DicoWeb web digital offset press is representative. At present, the "printing plate" of a digital printing machine is generally recordable and cannot be wiped off, and can be erased and cannot be recorded. Manroland has introduced the “print plate” of the DicoWeb web digital offset press, which can be recorded or erased. It is a hydrophilic metal sleeve made of special material on a plate cylinder. A heat transfer process is used to add an ink-repellent polymer to the surface of the drum and solidify it to form a "print plate". That is, the graphic to be printed, the laser is controlled by a computer controlled infrared laser, and the local area of the transfer belt is melted by the laser under the action of the laser, and the polymer having the ink affinity on the transfer belt is transferred to the surface of the plate cylinder, just like heat. Transfer the printer to transfer the color to the paper. The polymer with ink affinity transferred to the surface of the plate cylinder is identical to the printed image. Polymer transfer does not occur in the non-image portion. The "print plate" can be printed after it is ready.
After printing is complete, the image can be washed away. The "version" can be re-made on the metal sleeve when needed. There are many other types of digital web offset presses, such as inkjet printing or electrostatic imaging web offset presses (such as Hp).
Indigo's Omnius machine).
Sixth, combined printing press based on offset printing
Due to the development of technology and the increasing demand for printed materials in the market, sometimes only a single offset press can not meet the demand. Therefore, a combination printing machine of different printing methods has appeared. At present, the combination printing machine mainly based on web offset printing has the combination of one or more units of units such as flexo, gravure, silk screen and digital printing. Give full play to the advantages of various printing methods. This combination is primarily based on the specific requirements of a particular user.
Seven, reduce noise
The web offset press is relatively noisy, especially in the folding section. In order to improve working conditions and protect the environment, various measures must be taken to reduce noise. The current main measures are:
1. Improve machine structure: This is the fundamental solution. Such as improving the accuracy of certain parts and reducing noise, the folding machine's folding knife and the improvement of the splint create conditions for reducing noise.
2. Partial closure: Because of the high speed operation of the web offset press, it is still difficult to completely solve the noise from the vibration source. Therefore, the method of partial closure is generally adopted. In the high-noise area, it is partially enclosed by sound insulation board, foam plastic and sound absorbing material. For example, the folding cylinder of the folding machine is partially closed, or the folding machine is completely closed. Some closed the entire machine, leaving only the center console outside, and some closed the console.
3. Construction of sound-absorbing workshops: wall-mounted sound-absorbing materials, etc.
4. With silencer headphones: Despite the above measures, it is still impossible to completely solve the problem, even if the machine is completely closed, sometimes the operator must operate directly on the press. In this case, or without other measures, the operator must wear a silencer headset.