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Manufacturers talk about the status, function and application of offset printing machine (Part 1)

Introduction to the status, function and application of the key printing machine in this issue. The following excerpts are the introduction of the technical functions and applications of the top printing machine manufacturers in the industry, such as Heidelberg, Manroland, gaobao, Komori, Mitsubishi Heavy Industries and other companies' senior engineers. (Note: the content of this issue is collated and provided by Zhaoyang, a senior friend of pizza hut printing art)

Heidelberg: Mr. shaoyuanlin

I. mechanical structure of offset press

the main premise of efficient production of sheet fed multi-color offset press is a stable and reliable paper feeder. Therefore, all major offset press manufacturers have incorporated it into their own production system

at present, according to different substrate materials and specifications, the paper feeding method used by the sheet fed offset press is the step belt type. The vacuum suction belt type paper feeding under the standard paper feeding has its own advantages. The step belt type is used on the boot. The reason is that it has a stable structure. The accurate paper feeding forms a right angle with the guide gauge. In addition, the paper pressing wheel, brush and flatbed can be widely used for a variety of substrate materials, such as corrugated paper, slightly curled paper, etc, This is very important for paper with unstable printing specifications and performance

under medium format, such as four open and eight open offset press, the paper is transported by suction belt, because the operation and adjustment are simple and easy

in order to adapt to the current situation of short version operation, that is, frequent conversion of operation and paper size, Heidelberg timely launched a preset paper feeder with higher reliability and speed. This system retains the structure and mode of the traditional step belt, but has been optimized in many aspects to make the system tighter and convenient for automatic operation and control. Its characteristics are as follows: first, the paper forms an accurate method structure with the front gauge and side gauge to ensure the reliability and speed of paper feeding; Second, the lifting of the paper stack is stepless rather than step-by-step, which can be lifted according to the actual thickness of the paper to maintain a stable distance from the suction nozzle; Third, the semi closed system has a positive effect on noise reduction, dust prevention and maintenance free

in addition, for the early and late arrival of paper in the process of paper feeding, Heidelberg adopts automatic correction within the angle range of 200 ~ 312 by adjusting the swing tooth picking speed, rather than the traditional fixed angle correction

The roller layout and arrangement of the printing part is one of the hot topics in the industry at present. In fact, in the face of diverse and specialized market demand, whether it is seven o'clock or five o'clock, it has irreplaceable characteristics

the characteristic of 7o'clock is that the paper of each color group is handed over after printing, and it is beneficial to arrange large rollers, such as double diameter embossing rollers, which is very beneficial to thick paper printing (mainly packaging printing) that requires large curvature, but practice shows that this method is not perfect for thin paper based publishing and commercial printing

the five o'clock method is beneficial to the ink road with better arrangement

Heidelberg follows the natural demand of market segmentation and adopts seven point roller arrangement for SM102 and CD102. SM102 is a three roller (a single diameter, double diameter and B single diameter) transmission and turnover system, and the rubber roller, embossing roller and a single diameter paper transfer roller are almost in a line layout, which is very conducive to the transmission of printing paper (even full page printing is very good); CD102 uses double diameter imprint drum and triple diameter paper transfer drum as paper transfer system, and its advantages have been well known

for SM102, Heidelberg also does not use the air cushion paper guide system, but uses a metal sleeve (the so-called micro jaket device) with ultra-fine irregular chrome plated bumps on the surface, which is installed on the embossing cylinder printed after turning, to prevent the dry surface from being scratched and rubbed under the printing pressure

Heidelberg also did not use air cushion conduction mode on the anti rubbing and scratch device printed after turning over, but adopted measures such as coating silicon metal anti rubbing and dirt film on the transfer and storage paper drum, super blue cloth and steel sleeve

in fact, one of the focuses of the dispute between the number of rollers and the arrangement mode is the impact of paper handover dislocation caused by different paper handover times on the printing quality

Heidelberg's view is that the number of paper handover times has no substantive impact on the printing quality. The key is to consider the accuracy of the handover structure itself. Practice has proved the correctness of this view

for roller pillow printing, it should be determined according to the specific structural characteristics of rollers, transmission gears, bearings, etc. From the current level of offset printing machine manufacturing technology, roller pillow printing can ensure high-quality printing, low-noise operation and machine durability, and ensure that the hydraulic oil can meet the work needs

Heidelberg's inking and moistening system is also very characteristic. First of all, it has 21 inking rollers, which adopts the front longitudinal type (the first two inking rollers are inking, and the last two inking rollers are inking). There are only 8 inking rollers in the shortest ink path, which can realize the rapid response of ink flow

the moistening system is a five roller structure with automatic speed compensation function. Its advantage is to quickly achieve ink balance and maintain the stability of water supply when the printing speed changes

when printing small format or large area non image area moving parts, polycarbonate can be replaced in the utilization of these needs. Because the demand for fountain solution is less than that of ordinary moving parts, it is necessary to reduce the water supply of bucket roller accordingly. Heidelberg's practice is to partition the bucket roll relative to the (32) ink area, and use a row of axial adjustable blowers to evaporate the excess fountain solution

the paper receiving part has an important impact on the production speed and print quality of the offset press. Heidelberg has introduced the air blowing and paper guiding device, which can make the paper smoothly and without scratches into the paper stack, while the double powder spraying device not only makes the paper stack smooth and neat, but also saves up to 30% of the powder spraying

II. Automation and integration

the automation level of offset printing machine is one of the focuses of competition among manufacturers. Its development purpose is to free operators from daily complicated manual operations, so as to focus their attention on printing quality and efficiency, and also enable users to have the means to win the competition in the environment of soaring short edition operations

further improving the automation level of offset printing machine is based on the continuous improvement and optimization of the mechanical performance and electronic control degree of the machine, so as to pre adjust the specifications of printing materials, realize the automatic monitoring and control of printing quality, configure full digital electronic display system, and realize integrated operation and management, so as to achieve better quality, shorter preparation time, reduced maintenance time, and higher output

Heidelberg has added functions such as image color control and automatic online registration control in these aspects, which has won praise in the industry

in order to avoid the change of printing color and ensure stable printing quality, Heidelberg is the first to use spectroscopic measurement technology to scan images and synchronously adjust online color

the online automatic registration and alignment system not only performs rapid fine-tuning registration at the beginning of printing, but also continuously monitors and corrects the whole printing process, which can greatly reduce the machine registration downtime and paper waste

integration is the development direction of the future printing industry, because printing is transforming from a simple link to a complete production process (including pre press and post press), and digitalization is undoubtedly the leading factor leading to this transformation

digitalization and integration will optimize and automate the changes of information such as efficient production planning, automatic machine presetting and effective production data capture. As a result, the operation preparation time and production time are further shortened, and at the same time, the quality of printed matter and remote service reach a new high

MAN Roland: Mr. Zhang Jianfa, product sales director

I. about the structure of the offset press

the paper feeding part is the part with more manual participation in the traditional sheet fed offset press, but the modern offset press has higher requirements for the accuracy, stability and automation of paper feeding in the case of high-speed multi-color printing

in order to make the paper conveying stable and accurate, the pendulum paper delivery mechanism and the front gauge are the mainstream of the design, and the side pull gauge and the paper feeding speed change mechanism of various manufacturers (used to ensure that the instantaneous speed of the high-speed paper reaching the front gauge is zero) are different. Roland Offset Press is famous for vacuum paper feeding, variable-speed suction belt and pneumatic side pull gauge; It uses the position switch to accurately control the left and right of the paper stack and the front and rear of the paper feeder, which is particularly important when the double printing and the paper stack are uneven

when preparing for the prepress operation, input the thickness of the paper into the console, and then the precise and fast pre adjustment of the paper feeder, front gauge, side gauge, powder spraying device and printing press can be automatically completed, so as to reduce the quasi stop time and improve the production efficiency

at present, the paper specification preset function is the basic configuration of modern sheet fed multicolor offset printing machines

The printing part is the heart of the printing machine. After years of practice and theoretical discussion, the three rollers of the printing part are arranged at seven o'clock, and the double diameter structure of the embossing roller and the paper transfer roller has become the mainstream of the split multicolor offset press. In the past, the single diameter embossing roller and the double diameter paper transfer roller were arranged at five o'clock, such as the traditional four start series of several large manufacturers. The following advantages of using double diameter embossing cylinder are well known: first, the number of paper handover between multi-color units is reduced, so that the paper handover error is greatly reduced; Second, the paper red is printed during the period of taking the paper out of the impression cylinder, and then handed over to the paper transfer cylinder, so as to avoid overprinting errors caused by the printing of the end of the paper; Third, due to the large curvature and smooth surface of the drum, the deformation of dot transfer can be reduced during stamping

in addition, when the offset press is worn and aged for a certain period of time, when printing with the maximum paper width in this arrangement, the paper, regardless of the thickness of the paper, will not drag the print

for the combination mode of multi-color machine color, the linear printing mode with overturn of several major printing presses in Germany has the characteristics of low center of gravity of the whole machine, good rigidity and top-down ink path, which is beneficial to ensure the printing quality and stability. However, each has its own solution to the problems of dirt, tearing, front and back registration, double mouthing and so on caused by overturn. The double-sided sheet fed double-layer multi-color offset press, which is launched by Japanese manufacturers, has the advantage of small floor space because the ink path of the lower color group is from bottom to top, which will have an impact on the print quality and is inconvenient to maintain

ink supply and water supply system is the key to ensure ink balance and prevent some common printing failures. At present, two or three factories, including Manroland, have adopted the rapid reaction ink path system, which is characterized by a small number of ink rollers (less than 16), large diameter, good heat dissipation performance, and is suitable for high-speed printing. The ink rollers are only circularly cooled during water free offset printing and UV printing

in addition, when printing prints with different contents, such as packaged prints with large ink floor and commercial prints with thin lines and single ink color, it is very important to output ink at a uniform speed at all speeds. Only in this way can the viscosity of the supplied ink be consistent. For this reason, Roland Offset Press has a variety of programs on the ink supply cycle, 1:3:6:9:18 for initial setting, so as to ensure the stability of printing quality

II. About automation and auxiliary functions

in order to improve the automation of sheet fed multi-color offset press, improve printing quality and reduce labor level, all manufacturers have adopted similar measures

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