Offset of water and ink marks during the printing process of the offset press is a more difficult problem for the operator. Especially small-scale book printing factories, they have been using the J2101 machine as the main equipment. Due to long-term overload operation and improper maintenance, water and ink bars are more prominent than high-speed machines. According to the experience of the older generation of printing workers for many years and the phenomenon of water and ink bars appearing in the J2101 equipment used by our factory, we have done a little immature analysis for the reference of the operators of small-scale printing factories.
In general, the offset press has water and ink bars, both caused by mechanical wear and caused by improper adjustment. After water and ink bars appear, we must look for the reasons from many aspects and carefully analyze them to see whether they are ink bars or water bars. We know that ink bars are dark dots or stripes with regular or regular patterns on the Internet or in graphics. The width is about 5 to 8mm, and the outlets are enlarged. The water bars are printed on certain printing surfaces. The text appears irregular, narrow, light-colored lines. Whether it is a water bar or an ink stick, it will directly affect product quality. Therefore, the operator should understand and grasp the main reasons for the emergence of the bar, so as to solve it in time.
1. Drum gears are heavily worn by the ink bars. The gears of the J2101 Offset Press are basically exposed. The machine often has oil, paper, and ink penetrating into the teeth during its use. It accumulates for a long time and the top tooth phenomenon occurs. When the plate cylinder and the blanket cylinder are exposed to excessive pressure, the gear clearance is too small, and the gears cannot mesh with each other accurately, that is, jitter occurs during printing, and the surface of the cylinder generates large sliding friction. At this time, the printing plate may have ink bars equal to the pitch of the gears, and dots or images on the printing plate are easily damaged and the printing force is reduced.
2. Drums created by excessive pressure between the rollers. Many plants do not do fine work on the 01 leveling machine, seriously affecting product quality. In particular, operators who have been operating for a long time have blindly increased their pressure. They have not taken serious measurements when changing blankets and plate pads, and have noticeably heard vibrations when printing. We know that, according to normal pressure, the compression between the plate cylinder and the blanket cylinder does not exceed 0.1 to 0.15 mm, and the compression of the blanket cylinder and the impression cylinder does not exceed 0.15 to 0.2 mm. If you add padding paper at random, it will cause excessive pressure. Therefore, it is easy to produce ink bars.
3. Dumping impact produced by the ink bar. The momentary vibration of the skip on the 01 impression cylinder is large when the paper is picked up. At this time, the drum is liable to produce instantaneous speed change, and the several gears on the drum are also subjected to the greatest force and are easy to wear. As time goes by, it produces ink bars. The position where the ink stick appears on the printed sheet is generally fixed at a distance of 7~8mm from the mouthpiece. When this happens, the tipping bucket and strike bolt should be replaced to change the position of the gear, stray the worn tooth, and loosen the spring force on the tipping bucket to avoid excessive vibration and reduce wear.
4. Roller sorting does not cause ink bars. General 01 machine has four ink roller, and the diameter is not the same, the purpose is to avoid the production of ink bars. For example, the four inking rollers with diameters of 81, 77, 76, and 79mm should be arranged with a diameter of 81, 77, 76, and 79 mm from the front row. If the rubber roller is installed, the sorting is incorrect or the pressure is not properly adjusted, and the ink stick is easily generated.
5. Ink bars caused by excessive pressure between the rubber rollers or the ink roller. When adjusting the ink roller pressure, it is necessary not only to carefully adjust the ink roller and plate pressure, but also the pressure between the ink roller. If the width of the unilateral indentation exceeds 6 mm, the ink stick is often generated on one side. Some small factories use 01 machine-printed books and periodicals, do not frequently scrape the rubber roller, and the rollers are easy to age and harden, and the friction force on the printing plate increases. When the roller gap meets the edge of the smashing mouth, instantaneous bouncing occurs. Produce a more pronounced ink bar. Therefore, when adjusting the ink pressure on the printing plate, it is necessary that the width of the ink mark on the printing plate is 5, 5, and 4 mm, and the two ends are parallel when the printing plate pad conforms to the standard. Restoring... (to be continued)