Fault analysis of the first deep and second shallo

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In offset printing production, when a sheet fed offset press prints a large graphic area or a field version of a printed matter, the ink color of the same printed matter is often deep in front and light in back. In addition to improper process operation and adjustment, the more direct reason for this phenomenon is the influence of the layout and structure of the machine itself

in recent years, Chinese plastic machine enterprises have made the dimensional stability of printing molded parts better, expanding the development of emerging markets for extruders. 1. the impact of cylinder structure

in the process of inking from the inking roller to the printing plate, when the inking roller is in the empty position of the printing plate cylinder, the inking roller does not inking, and the ink stored on the inking roller is large. Then the cylinder rolls forward, and each inking roller inks to the front of the printing plate with the maximum amount of ink, As the inking roller continues to roll on the ink, the amount of ink on the inking roller gradually decreases. When rolling to the trailing part of the printing plate, the amount of ink on the inking roller is very small. It is easy to cause that the electro-hydraulic servo universal testing machine is often used to prepare 26 foot wide products after several sets of ink are deep before high load operation

2. influence of ink roller arrangement

the ink rollers of the ink conveying device are generally divided into two groups: ink feeding and ink receiving. The arrangement of the two groups of ink rollers is different for different models. The ink path of the uniform distribution ink roller arrangement is divided equally by two paths, and the four ink rollers uniformly ink. For this ink roller arrangement, if the adjustment is improper, the latter two ink rollers can not supplement the ink, even the ink and recover the excess ink layer, and the printed matter is prone to the phenomenon of deep in front and shallow in back. The former two inking rollers account for 90%, and the latter two account for 10%. Such distribution generally does not produce the phenomenon of deep ink in front and shallow ink in back

3. process remedy and precautions in operation

(1) the ink roller that is too smooth and aging should be replaced in time to ensure good ink transfer performance and sufficient ink storage on the surface of the ink roller, so that the ratio between the ink consumed by printing and the ink storage of the ink roller is as small as possible, so as to enhance the ability of the ink roller to adjust the ink volume and make the ink color of the printed matter consistent

(2) master the fluidity and viscosity of the ink, because the fluidity and viscosity of the ink directly affect the transmission speed of the ink and the ink storage capacity of the ink roller

(3) strictly control the moisture content of the layout, prevent excessive emulsification of the ink, and ensure the normal transmission and adhesion of the ink

(4) for the uniform distribution ink path layout, when adjusting the pressure of the plate inking roller, the first two should be heavier and the last two should be lighter. The contact width between them is generally adjusted to 6mm, 6mm, 4mm and 4mm from front to back. The pressure between the inking roller and the inking roller shall be equal to the contact pressure between the inking roller and the plate surface. It is ideal that the rotation of the inking roller should rely on the equivalent friction on both sides. If the pressure difference between the two sides is too large, the rotation of the inking roller on the inking roller or plate surface will become friction sliding rather than pure friction rotation, which will not only affect the normal transmission of ink, but also affect the uniform coating of the plate by the inking roller

(5) padding paper at the place with light ink color can increase the printing pressure and also play a remedial role

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