Printing pressure function and adjustment of the h

2022-08-07
  • Detail

The effect and adjustment of offset press printing pressure (III)

it can be seen from the above formula that LPB or LBI and their influencing factors are linear, that is, LPB or LBI will change with the increase or decrease of the influencing factors. It can be seen from the analysis in 1 that the thickness of the paper (TZ) and the center distance (ABI) between the rubber cylinder and the impression cylinder only affect the pressure between the rubber cylinder and the impression cylinder; The thickness of the printing plate (TP), the thickness of the printing plate liner (TPC) and the center distance between the printing plate cylinder and the rubber cylinder (ABP) only affect the pressure between the rubber cylinder and the impression cylinder; The thickness of the blanket (TB) and the thickness of its liner (TBC) affect the pressure at both places. This has guiding significance for adjusting the printing pressure. When it is only necessary to change the pressure between the embossing cylinder and the rubber cylinder, the center distance (ABI) can be adjusted or the paper can be replaced. It is practically impossible to replace the paper, so the most commonly used method is to change the center distance of the cylinder, but the change of the center distance should consider the influence of the paper thickness. When it is only necessary to change the pressure between the rubber cylinder and the printing plate cylinder, adjust the center distance (APB), or change the printing plate, or change the printing plate, or change the thickness of the printing plate liner. It is rarely encountered in the actual process of changing the printing plate, and it is not used much to adjust the center distance. The main reason is that there is only ink between the rubber and the printing plate, and the ink is basically the same. Therefore, it is relatively common to change the thickness of the pad under the printing plate. When the pressure at both places needs to be adjusted, the thickness of the blanket or the thickness of the liner under it can be changed. When the pressure at both places needs to be adjusted, the thickness of the blanket or the thickness of the liner under it can be changed. The actual process of changing the thickness of the blanket is very difficult. 9. Power supply of the pressure control system: AC220V, 1.5KW, rarely encountered

it is usually used to change the thickness of the liner under it. Summarize the above analysis:

① when only the pressure between the rubber cylinder and the imprint cylinder is adjusted, the most commonly used is to adjust the center distance between the two cylinders. ② When only adjusting the pressure between the plate cylinder and the rubber cylinder, the most commonly used is to change the pad thickness under the plate. ③ When the pressure at both places needs to be adjusted, the most common is to change the thickness of the pad under the rubber drum

2.7.4 optimal printing pressure

in the previous section, the general methods of forming and adjusting the printing pressure are analyzed in detail, but in the actual process, the printing pressure must be able to ensure the good transfer of ink, so there is a problem of selecting the optimal printing pressure. The best printing pressure should be: complete imprinting, smooth and bright, distinct layers, bright colors and minimal deformation. In order to obtain the best printing pressure, it is necessary to make the paper, ink, fountain solution, printing plate, printing equipment, printing process, printing environment and lining outside the optimal suitability state

from the perspective of paper, the LBI value is different for different papers. The LBI required for coated paper is small, and the LBI required for offset paper is large. Because the surface roughness of offset paper is large, some places may not be printed without increasing LBI, while the surface roughness of coated paper is small and LBI is large, the deformation of imprint increases rapidly, so it is easy to paste

from the perspective of ink water balance, ink water balance is the guarantee of print quality. The greater the printing pressure, the greater the possibility of imprinting spreading, and more water is required to prevent the expansion of ink. Therefore, when the printing pressure changes, the ink balance also changes. Considering the ink only, it can be seen from the pressure curve that the pressure must be within the BC section, and the ink transfer is the most ideal and sensitive to control

from the perspective of printing equipment, the smaller the printing pressure, the greater the vibration during periodic impact and ozone aging test. If only the printing equipment is considered, the printing pressure should be zero, but in fact this is impossible. It is better to make it in section 2.7.3 Status described in

from the perspective of printing process, the transfer effect of the first color ink is the best, and the transfer effect of subsequent colors is becoming more and more difficult. According to the separation law of ink, the later the value of LBI should be greater. From the perspective of ink, the more sticky the ink, the greater the pressure; The thinner the ink, the lower the pressure

from the perspective of printing plate, its surface should have a good hydrophilicity with a net financial debt of 9.9 billion euros as of June 30, 2014, and the graphics and text should have good ink affinity and water repellency. Another is to hinder the deformation of the imprint. From this point of view, gravure is better than relief. From the printing environment, when the temperature and humidity in the environment change, the paper, ink and fountain solution will be affected. An oil filter should be set on the oil suction nozzle to cause the pressure change

to sum up, the best way to adjust the printing pressure is to make the gear in the standard meshing state, and to achieve the best printing suitability by changing the thickness of the pad

when printing thick paper, the best adjustment method of printing pressure is:

① reduce the thickness of the pad under the rubber drum

② increase the pad thickness under the plate cylinder

③ slight difference can be compensated by the change of center distance

Copyright © 2011 JIN SHI