Explain the progress of ink transfer research by sheetfed offset press (one)
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This paper mainly describes the experimental study of ink transfer and how scientific research methods are applied to today's research through sheetfed offset presses. The goal of industrial-oriented scientific research is to find the latest solutions to the problem in the system, to increase technical capabilities and increase production capacity in the new industry development framework; and to save test time and cost through in-depth theoretical discussion and research. Achieve high automation of printing industry production and improve economic efficiency.
Currently, the printing quality and productivity required for offset presses require high precision and high reliability. The maximum error of the ink layer thickness during printing is approximately 0.05
Μm, or the deviation of the position of the color separation image of the color image, the maximum distance error of one color separation image from the edge of another color separation image is 0.02 mm, which is technically acceptable under normal printing conditions and corresponding printing parameters. The scope.
Such requirements can only be met through intensive research into the core process of offset printing, which in turn promotes the development and production of printing presses. The complexity of the printing process and the printing press requires a lot of scientific research.
In addition to the discovery of research activities from non-specialized printing machines for press engineering, there are also special press research activities conducted by printer and printing equipment system manufacturers and many research institutions around the world. Businesses and research institutions have also participated in joint research projects that focus on basic research, productivity enhancement and further development.
There are commonly used tools and methods for these experimental and theoretical research studies in research activities, as well as the development of new tools and the development of further research methods. This paper mainly introduces the scientific experimental research of ink transfer.
Design and calculation of ink transfer system
1. Ink transfer system design
The ink transfer system for offset printing transfers ink from the ink fountain to the printing plate to form a thin layer of ink of a certain thickness on the printing plate. It is apparent that the amount of ink transferred depends on the image to be printed, and the amount of ink in the lateral direction to be printed varies depending on the printed image. For this reason, the control of the ink is generally performed by partitioning. Due to the precise requirements for the thickness of the ink layer and the prevention of diffusion effects, the ink transfer system design is one of the technically extremely difficult and complicated components of the printing press.
The development of each type of offset press depends mainly on the design of the ink transfer system, and the ink transfer system should best meet the following requirements:
a, a highly uniform ink layer in the longitudinal and lateral directions of the printing paper;
b, rapid regulation, sensitive response;
c. The split between the thin layers of ink of each color separation image is small, that is, low sensitivity to the effect of splitting (such as changes in temperature and humidity);
d, a large range of control variables for the amount of ink and wetting fluid;
e, economic benefits, etc.
The parameters for designing the ink roller are mainly the material, diameter, arrangement and movement, and the number of ink rollers. In the optimization process of the development, time and cost of the ink transfer system, most of the mechanisms used in the traditional design of the ink transfer system are based on experience and test methods. Thus, through a systematic investigation of the ink transfer process of the ink transfer system, the purpose is to establish its theoretical basis and to accurately design the ink transfer system in most cases. In the early days, some people were looking for the regularity of the ink transfer system.
2. Calculation and simulation methods
In 1960, Mill first proposed a method for calculating the thickness of an ink layer in an ink transfer system. A balance equation is established for the amount of ink at each ink outlet, resulting in a balancing system. In this system, the thickness of the ink layer is unknown. Ruder proposed an accurate and simple method for determining the thickness of the ink layer for the geometric parameters of the ink transfer system.
Under the two algorithms proposed by Ruder, only the average ink layer thickness can be calculated. It is impossible to calculate the inclination of the thickness of the ink layer in the circumferential direction of the ink roller and the printing plate. In 1971, this problem was first proposed by Rech and solved with the aid of a computer.
For this calculation based on the angle-increasing method, all the ink rolls and the circumference of the drum are divided into sections of the same size. The thickness of the ink layer at each ink outlet is obtained by establishing an equation and solving the equation. Based on this algorithm, a further calculation method is introduced, which takes into account the parameters of more and more ink transfer systems, so that it should be able to better approximate the actual thickness of the ink layer. In the calculation method of finding and simulating as close to the actual situation as possible, it is crucial to determine the regularity, legitimacy and ink delivery parameters.
Presented by Patzelt and Ruder in the FGD research project, the NKTEAM simulation program reflects the latest developments in technology. It mainly considers the following parameters:
a, the geometric parameters of the ink transfer system; b. Continuous or intermittent ink delivery; c, ink transport in the circumferential and transverse directions; d, wetting fluid transport and evaporation effects; e, temperature; f. lateral partition; g, ink absorption.
The INKTEAM ink transfer system is an analog system. At the beginning, the ink transfer system is empty, the ink is separated, the ink is transferred throughout the ink transfer system, and each simulation calculation project recalculates the printing equipment until the thickness of the ink layer in the lateral direction of the printed sheet no longer changes, that is, until Achieve stable conditions. It can be seen from the calculated ink layer thickness curve that it is tested by two ink transfer systems in the length direction of the sheet.
In the first case, all the ink rollers and water rollers are in contact with the plate cylinder, and the consistency between the simulation and the test is not well satisfied. This can be attributed to the interaction between many of the parameters considered and the accuracy of their settings. Simply changing the percentage of the percentage of factors affecting ink splitting can lead to completely different results.
In the second case, the ink and the wetting liquid are simultaneously transferred to the plate cylinder through the wetting roller, and a good effect can be produced, that is, actually three ink rollers are idle, and the wetting system and the ink roller are passed through. A bridge between the wetting roller to transport the ink.