The three levels are: water roller leveling, ink roller leveling and roller leveling.
Three small things are: small water, small ink and small pressure.
The three diligence are: diligent in mixing ink, diligent in reading proofs, and diligent in watching the water in the drum.
(The following source: Printing and Packaging Business Network at 8: 40 on May 6, 2006)
The master level of offset printing "three leveling, two small leveling and one leveling" directly reflects the technical level of offset printing workers. The so-called "three-level" means that the offset press that requires debugging must have a flat roller body, a flat ink roller and a flat water roller; "Two small" means that the concentration of the bucket solution used in the printing process is small and the page moisture is small; "A balance" means that the ink on the printed page should be balanced. When the offset press is running, the axes between the rollers must be parallel and the plane of the rollers should be straight; The axis of ink roller should be parallel, the roller body should be straight, and the pressure between rollers should be uniform; The axis of the water roller should be parallel, the roller body should be straight, and the pressure between the water roller and the water roller should be uniform; The axis of roller body should be parallel to the axes of ink roller and water roller, and the pressure should be balanced and moderate. Determine the lining material according to the technical parameters given by the machine when it leaves the factory. The soft lining should be adjusted more smoothly by drawing the completed version, and the error should be below 0.03 mm.
1. Drum debugging
Drum is the main part of offset press, and its debugging is very important.
First, determine the center distance of the drum. It is very important to adjust the center distance of rollers so that the axes of two adjacent rollers are parallel, and it must be done carefully. It is worthwhile to spend more time in this respect. When detecting the gap between the roller and the roller pillow, the measured data must be measured patiently and carefully with a thickness gauge or a blown fuse. In order to be as accurate as possible, you can measure several times and several parts. The gap between the measuring roller and the roller pillow must be consistent to ensure that the axes between the rollers are parallel. Generally, the measurement is based on impression cylinder.
Then according to the technical parameter data of this offset press, the reasonable packaging is determined. The lining on rubber roller is generally divided into soft, neutral and hard, and different materials have different soft and hard characteristics. In 1980s, there was a heated discussion about the theory of drum lining. On the one hand, some people think that the radii of roller linings should be equal, that is, the theory of equal diameter; On the other hand, some people say that after the drum is lined, the diameter of the rubber drum is slightly smaller, that is, the unequal diameter theory. Both sides hold their own opinions and do not give in to each other. The focus of the debate is the distribution of printing compression deformation value (pressure), that is, which cylinder the λ value should be placed on. Compared with the radius of the drum, the λ value is very small. The theory of equal diameter and unequal diameter of rollers has the same point of view, that is, it is required that the linear velocities of the three rollers are equal in the running process after the rollers are marked, so that good products can be printed.
Whether the linear speed of the lined drum is equal or not can be identified in the following ways. In other words, after printing thousands of sheets of paper (especially domestic offset paper or book paper), paper wool and paper powder will stick to the rubber tire. If the paper powder and paper wool at the edge of the imprint are directional (the direction of biting or dragging the tip), it means that the linear speed of the drum is not equal. Only when the roller is lined and printed, the paper wool is piled up on the rubber roller without directionality, then this lining data is the best, that is, the roller is adjusted to the best running state.
2. Ink roller debugging
The inking system consists of more than a dozen inking rollers, separating rollers, inking rollers, ink fountain rollers and inking rollers with different diameters.
First, adjust the pressure between the channeling roller and the inking roller, and then adjust the pressure between the inking roller and the printing plate.
There are usually four inking rollers. The function of the two rollers that contact the printing plate first is mainly to supply ink, and the pressure is appropriate to provide enough ink for the printing plate. The two inking rollers that contact the printing plate mainly play the role of collecting ink, and the pressure should be appropriately small to make it clean.
Before pressure adjustment, a relatively flat printing plate with thickness error less than 0.02mm should be installed on the printing plate cylinder. Because the diameters of the four inking rollers are different, the pressure on the inking roller and the printing plate cannot be expressed by data. It is important that the pressure at both ends must be the same. When the machine is running, there is no obvious jump at both ends of the ink roller (touch both ends of the printing plate ink roller by hand). If the pressure of the inking rollers at both ends of the printing plate is inconsistent, or there is serious jumping on the printing plate, it will cause the relative friction between the inking rollers and the printing plate, which is easy to cause ink sticks.
3. Debugging of water roller
There are two kinds of water rollers, one is to transfer water with a colloid roller, and the other is to transfer water by putting water rollers on rubber rollers. The biggest weakness of water roller napping sleeve is the shedding of fluff during printing. If it is transferred to printing plates and printed matter, it will affect the quality of printed matter, especially printed matter with full pages or hollow characters. The water delivery system is generally composed of two water-striking rollers, a water-passing roller, a water-conveying roller and a bucket roller, and the general debugging focus is on the two water-striking rollers. When the machine is running, the water roller that first touches the printing plate is called the water roller, which plays the role of supplying enough water to the printing plate; The water roller that contacts the printing plate is called the water collection roller, which mainly plays the role of collecting excess water on the printing plate. Because of the different functions of the two printing plate water rollers, the debugging pressure requirements are also different: the pressure of the water supply roller is relatively greater than that of the water collection roller, and the watermark width of the water supply roller is generally about 5mm, and the watermark width of the water collection roller is generally 4 mm..
4. Barreled liquid
Barrel solution is generally weakly acidic, and its pH value should be controlled at 4.5 ~ 5.5. When ph