Editor's note: China's printing industry has introduced a large number of advanced printing presses. These printers all have the features of high degree of automation, high printing speed and good product quality. However, with the increase of the service life, the degree of wear and damage of the equipment is also increased. In addition to natural wear and tear, some parts are accelerated wear and damage due to the poor operating conditions of the equipment. If the normal maintenance and maintenance of the printing press cannot be performed normally, the technical performance of the equipment will be reduced, thereby reducing the printing quality. Improve the integrity of equipment, ensure that the quality of printing does not decline, production is carried out smoothly, and reduce the losses caused by improper maintenance. These further indicate that the offset printing and water transfer mechanism is composed of a water supply part, a uniform part and a water part.
1. Water supply part: It consists of water bucket, water bucket roller and water transfer roller. The main function of this part is to supply the water to the portion of the water that is quantified and timed.
2. The uniform part: It consists of a series of water rollers and a uniform roller. It rotates and axially circulates through the tandem roll and evenly transfers the moisture to the water roller. At the same time, due to the presence of surface active substances in the water bucket solution, the surface tension of the water can be reduced, so that the fountain solution can be evenly distributed on the water-impregnated roller covered with the flannel cloth.
3. The water part: It consists of a number of water rollers. The main role is to apply evenly and evenly the water in the blank part of the offset printing plate. In the water delivery mechanism of the offset press, the bucket series and the skewer roll are all chrome-plated materials. This is because metal chromium is the most hydrophilic, and the string water roller and the fountain roller are all chrome-plated.
Offset printing is a unique printing method using water. Because of the need for water, it is necessary for the water distribution agency to regularly and evenly supply water to the blank part of the printing plate. Then on the ink, that is, "before the water after the ink." Control the surface water quantity of the printing plate, use the least amount of water on the premise of not dirtying the plate, reach the balance of the offset printing ink, reduce the ink emulsification phenomenon, this is the premise that raises the offset printing quality.
1) The water fleece or water fleece sleeve used on the water roller is degreased and has good hydrophilic properties. The water fleece sleeve has countless pores and its adsorption is particularly strong, which ensures the hydrophilicity and water absorption of the water roller, and can play a good wetting effect on the printing plate.
2) The pressure of the water roller and the printing plate has a great influence on the print quality and the printing rate of the printing plate. The pressure is too high, the printing plate has a low printing rate, and wear quickly. The graphic part will produce a "flower pattern" phenomenon. At the same time, it will easily cause the water roller to beat to produce a "water roller white bar." However, if the pressure of the water roller and the printing plate is too light, the printing plate will not get normal water supply, which will cause the printing plate to be dirty.
When adjusting, first adjust the pressure between the water roller and the series water roller, and then adjust the pressure of the water roller and the plate. These two adjustments do not affect each other. In addition, adjust the water roller to ensure that the pressure at both ends of the same size. When the contact pressure between the water roller and the string water roller is too light, the amount of water obtained by the water roller from the string water roller is reduced, resulting in a dirty plate phenomenon.
4. In order to increase the utilization rate of the water roller and reduce the consumption of raw materials, it is necessary to keep the water roller clean and free of oil. In the printing process, the water roller is in contact with the surface of the printing plate, and the offset printing uses water to determine that the ink will be emulsified. A small amount of the emulsified ink is transferred to the bucket slot through the water roller, the water transfer roller and the string water roller. Therefore, the water roller cover of the water roller must be kept clean and free of oil. The surface of the fleece jacket is first exposed to oil stains, resulting in lipophilicity, which reduces hydrophilicity, and thus affects water delivery performance.
In order to ensure sufficient wetting of the water roller, encounter a long time shutdown, holiday breaks, should make the water roller suck enough water to prevent the water roller surface glue and ink dry, causing uneven water transfer. Before the offset printing is turned on, the water roller accumulates sufficient amount of water to contact the printing plate first, which can also reduce the possibility of dirty on the water roller.
When a rest day or a light color ink is changed from a dark color ink, the water roller must be cleaned. The cleaning method is: put the water roller into the water tank, first use the gasoline to cast the water roller, and brush evenly with a large brush. The ink on the fleece is fully dissolved by the gasoline, and then rinsed with clean water, while punching the brush. If it is still not clean enough, the steel sheet can be scraped off several times in the direction of the fleece sleeve, if the water fleece cover Dirty, can replace the new water jacket. In addition, the wetting solution in the bucket will have a large amount of sediment and dirt for a long time. This is mainly due to the fact that the water roller transfers the paper dust, ink, and ink from the printing plate over the past. This must be cleaned in time. Keep the buckets clean.