The three major effects of printing pressure
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The so-called drum center distance refers to the distance between the centers of two adjacent drums, which is numerically the sum of the radius of the two drum gear pitch circles.
The plate cylinder and the impression cylinder are hard surfaces, which are not easily deformed after applying pressure. The printing pressure is obtained by the elastic force generated by the blanket on the blanket cylinder. Therefore, the roller is in the printing process. The blanket cylinder and the other two rollers are not in a straight line, but a curved surface with a constant width. Usually, the maximum compression deformation value of the blanket is called the printing pressure in the production, and the maximum compression amount is actually The deformation value is the sum of the radii of the two-phase cylinders plus the thickness of the paper, the liner, and the actual center distance between the two rollers.
The effect of printing pressure is:
(1) Maintaining a rough printed surface to achieve complete contact. The surface of the paper, blanket and printing plate are rough and microporous. For these rough surfaces, it must be deformed under pressure to achieve reliable and complete contact. To overcome the roughness and unevenness of each printing surface, so that the ink and dampening liquid can adsorb to the solid surface to achieve effective transfer.
(2) Overcoming the attraction of ink molecules and enhancing the adsorption force, the ink molecules have a certain attraction force. When the ink adsorption force exceeds the attraction between the ink molecules, the ink begins to be transferred from the intermediate fracture, but the ink is in the adsorption transfer. The distance of contact between the transfer surfaces must be close to produce adsorption. Therefore, only under a certain pressure, the attraction between the molecules can be overcome to better adsorb and transfer the ink.
(3) Pressure infiltration. The ink is printed on the paper, wherein the binder has a penetration phenomenon on the paper, and the penetration of the ink on the paper can be divided into two physical phenomena: pressure penetration and free penetration.