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Detailed! Printing machine "water bar" and "ink bar" cleaning completeTime£º2021-09-01 Detailed! Printing machine "water bar" and "ink bar" cleaning complete The failure of water bars and ink bars in the printing process of offset presses is a more difficult problem for operators, especially for small book printing houses. Due to long-term overload operation and improper maintenance, the phenomenon of water and ink bars is more prominent than that of high-speed machines. Based on the years of work experience of the older generation of printing workers, the phenomenon of water and ink streaks has appeared in the practical operation, and some simple analysis is made for the reference of the operators of the printing factory.
Generally speaking, water bars and ink bars in offset printing machines are caused by mechanical abrasion and improper adjustment. After the occurrence of water and ink bars, you should look for the reasons from many aspects, carefully analyze them, and distinguish whether it is ink bars or water bars. We know that the ink bars are irregular or regular dark linear stripes appearing on a certain printing surface or pictures and texts, and the width is about 5-8mm, and the dots are enlarged; the water bars are dots or pictures on a certain printing surface. There are light-colored linear streaks that shrink randomly. Whether it is a water bar or an ink bar, it will directly affect the quality of the product. Therefore, the operator should understand and master the main reasons for the tap, so as to solve it in time. Ink bar caused by severe wear of roller gear When the machine is in use, oil stains, paper scraps, and ink stains often penetrate between the teeth, and they keep accumulating for a long time, resulting in the phenomenon of top teeth. The pressure between the printing plate cylinder and the blanket cylinder is too large, the gear gap is too small, and the gears cannot be accurately meshed with each other, that is, jitter occurs during printing, and the surface of the cylinder produces relatively large sliding friction. At this time, ink bars equal to the pitch of the gear may appear on the printing plate, and the dots or graphics on the printing plate are easily damaged, and the printing resistance is reduced.
Ink bars caused by excessive pressure between the rollers Many factories have not done detailed work on the machine sanping, which seriously affects the quality of their products. Especially when the operator who has been operating for a long time blindly increases the pressure, and does not measure carefully when changing the blanket and printing plate liner, the vibration sound is obviously heard during the stamping. We know that under normal pressure, the compression between the plate cylinder and the blanket cylinder does not exceed 0.1¡«0.15mm, and the compression between the blanket cylinder and the impression cylinder does not exceed 0.15¡«0.2mm. If you increase the liner paper at will, it will cause excessive pressure. , It is easy to produce ink bars. Ink bar caused by tipping bucket impact The instantaneous vibration generated by the instantaneous vibration of the machine's impression cylinder produces a relatively large force. At this time, the cylinder is prone to instantaneous rapid change, and the several gears next to the striker on the cylinder also bear the greatest force, which is easy to wear and over time. Produce ink bars. The position of the ink bar that appears on the printed sheet is generally fixed at a distance of 7 to 8 mm from the gripper. When this happens, replace the tipping bucket and the striker, change the position of the gear, stagger the worn teeth, and loosen the spring force on the tipping bucket to avoid excessive vibration and reduce wear.
Incorrect order of rubber rollers causes ink streaks Generally, there are four inking rollers of 01 machine, and the diameter is different, the purpose is to avoid the production of ink bars. For example, four inking rollers with diameters of 81, 77, 76, and 79mm should be arranged in diameters of 81, 77, 76, and 79mm from the front row to the back. For example, when the rubber roller is installed, the sequence is incorrect or the pressure is adjusted incorrectly, which is easy to produce ink sticks. Between rubber rollers or ink rollers Ink bars caused by excessive pressure on the printing plate When adjusting the pressure of the ink roller, not only must the pressure of the inking roller and the printing plate be carefully adjusted, but the pressure between the ink rollers must also be uniform. If the width of the indentation on one side exceeds 6mm, the ink bars are often produced on one side. Some small factories use 01 machine to print books and periodicals. They don¡¯t often scrape the rubber rollers. The rubber rollers are easy to age and harden, and the frictional force on the printing plate increases. When the gap of the cylinder meets the edge of the gripper, it produces instantaneous jump, so the gripper is easy. A more obvious ink bar is produced. Therefore, when adjusting the pressure of the inking roller on the printing plate, it is necessary to follow the order of the inking roller when the printing plate liner meets the standard. The width of the ink marks on the printing plate is 5, 5, 4mm, and the two ends are parallel. . Ink bars caused by wear of bridge gears The two bridge gears of the ink string roller are equipped with eccentric devices. After proper adjustment, the screws must be locked to leave a certain gap. Noise is generated when too tight, if the lubrication is not in place, and there is dirt and oil between the teeth, it will cause serious wear of the gears, resulting in inaccurate gear meshing, jittering of the ink roller, and obvious ink streaks on the printing plate. Ink bars caused by aging and hardening of rubber rollers In printing plants with book printing as the main work, if the offset printing press operators do not wash the rubber rollers frequently, the ink is accumulated on the rubber rollers for a long time, and the dust in the paper penetrates the surface of the rubber rollers, and the surface of the rubber rolls after friction, cracks, etc. The luminescence becomes hard, and the ink distribution performance of the rubber roller is reduced, resulting in obvious ink streaks. If the aging of the rubber roller is not serious, but a bright film is formed on the surface, the rubber roller can be removed, and the surface can be rubbed lightly with pumice powder to completely remove the ink on the surface, and the ink streak will disappear or lighten. If the rubber rollers are seriously aging and have no elasticity, they will slip between the rubber rollers during operation, and the rubber rollers must be replaced. Ink bar caused by vibration The neutral position of the machine drum is relatively large. During operation, the pressure between any two drums constantly disappears at the neutral position and appears at the entrance. The impact of the roller entering and exiting forms a vibration source, especially the vibration generated by the impact of the tipping bucket. Therefore, the existence of the vibration source of the offset printing press is the main reason for the vibration of the lever. When the machine is running normally, these vibration sources instantly destroy the uniform rotation between the drums. Once you find the vibration lever, you should find the source of the vibration first, and the symptomatic lower ring problem will change from complex to simple. Plate cylinder and blanket cylinder Ink bars caused by excessive printing pressure between the blanket cylinder and the impression cylinder. Theoretically, most require the width of the print between the plate cylinder and the rubber ballast to be 4-6mm, and the width of the print between the rubber cylinder and the impression cylinder to be 5-7mm. However, after the operator adjusts the center distance accurately, Inaccurate measurement, found that the imprinting was false, and randomly increased the liner paper. Sometimes the blanket was not stretched tightly, and when the pressure was high, rushing back, the blanket will appear on the blanket like a washboard-like ink streak. Ink bars caused by other reasons For example, if the ink is too thin, the stickiness is small, the sticks are easy to come out, the ink sticks are easy to come out when the coated paper is printed on the ground or the screen, the blue ink is easy to come out of the dark ink; the thickness of the liner is uneven, the quality of the blanket is bad, etc. . Water bar The water bar on the low-speed machine is generally caused by the large contact pressure of the water roller on the printing plate. It is characterized by a shiny, fixed bar at the grip of the printing plate. The water supply mechanism of the offset press is controlled by a cam, and the water is transferred at the neutral position of the printing plate cylinder. The position of the control cam of the water transfer roller and the contact time of the printing plate should be adjusted correctly, and the appropriate pressure should be used. Generally, the machine has two water rollers, as long as it is adjusted well, only one water roller can be used. According to observations, the lower one is generally used, but when changing the water roller, the operator points the machine to the neutral position and uses a crowbar to pry out the water roller, so that the water roller bracket is easy to loosen or cause the water roller to deform, so the upper one is still used. The root is more suitable and can prevent the production of water bars. |
