[Section Indian Network () Reuters cot as one of the important components of offset printing machine, and printing quality are closely related, and therefore, how to scientifically correct use and maintenance of rubber roller is very important. Take a 4-color offset press as an example: the total set of ink rollers of the four color groups of the machine is worth about 50,000 yuan. If carefully protected and scientifically adjusted, the average service life can reach 2 years; if used improperly, the average use Life expectancy will be shortened to 1 year or half a year. Therefore, strengthening employees' sense of responsibility and improving their operational skills are of great significance in ensuring product quality, reducing maintenance costs, improving economic efficiency, and promoting enterprise development.
1. Analysis of the causes of abnormal damage of rubber roller
According to the author's many years of practical experience, the reasons for the abnormal damage of the rubber roller are generally the following.
(1) When installing and disassembling, it is not handled with care and the roller or rubber surface is damaged.
(2) The rubber roller shaft head and the bearing are not tightly matched or the bearing performance is not good, so that the rubber roller is subjected to friction, extrusion, etc., and it is easy to accelerate the cracking and aging of the rubber roller.
(3) Too much accumulation of ink, ink residue and other impurities on the rubber roller accelerates the friction and aging between the rubber rollers, making the surface of the rubber roller full of numbness, and it is impossible to accurately transfer water and transfer ink.
(4) improper selection of cleaning agent for rubber roller, such as gasoline, reducing agent, strong acid, strong alkali, etc., will cause cracking and slag on the surface of rubber roller rubber.
(5) The pressure between the rubber rollers is too large, so that the rubber roller is deformed by extrusion, the rubber heat expands, and the rubber core is directly unshelled, which causes the rubber roller to be scrapped.
(6) The high temperature of the workshop causes the rubber roller to dissipate heat in time during the operation, and the rubber cohesion temperature is continuously increased to accelerate the aging of the rubber.
(7) The ink dries too fast and the emulsification is serious, and it will accumulate at both ends of the rubber roller, thereby increasing the pressure between the rubber rollers in the disguised phase and accelerating the wear and tear.
Ageing.
(8) The ink release button at both ends of the ink fountain is closed, causing no ink replenishment at both ends of the rubber roller, so that the rubber roller is often in a dry friction state and damaged.
(9) In the multi-color printing machine, since the color of a small number of printed materials, resulting in another color roller set idle time, it is in a dry state and friction damage.
(10) The printing plate is not tight or the clamping clip is not tight, so that the printing plate tip is often broken. When the rubber roller is pressed against the plate cylinder, the rubber surface of the rubber roller will be scratched, causing the rubber roller to be scrapped.
(11) The rubber roller is improperly stored, for example, it is not stored in the dark, and the rubber roller is crushed and scratched by sharp objects.
There are many reasons for the abnormal damage of the rubber roller, but if you analyze it carefully and find out the root cause of the problem, you can avoid the damage of the rubber roller.
2. The correct use of rubber roller
1. Correctly install the rubber roller bearing
First of all, the rubber roller should be cleaned on both sides, and then the bearings with specifications and models that meet the design requirements of the machine should be selected, and a layer of lubricating oil should be evenly applied on each mating surface, and the bearing should be evenly applied with a special sleeve for mounting the bearing. Make it fit in place. Do not apply force directly to the bearing surface to avoid damage to the bearing.
2. Specification to adjust the pressure between the ink rollers
During the printing process, the water roller and the ink roller must continuously and evenly supply the printing plate with an appropriate amount of water and ink, so as to obtain a print with consistent ink color. Therefore, between the rubber roller and the rubber roller, between the rubber roller and the printing plate, the proper pressure must be maintained to achieve good ink transmission. In order to ensure the pressure between the water roller and the ink roller, the method of measuring the width of the ink bar must be adopted, mainly including the following points.
(1) Evenly add an appropriate amount of yellow ink on a clean rubber roller, and then run the machine to evenly distribute the ink on the surface of the ink roller.
(2) Jog the printing press and check the width of the pressing bar. It is worth noting that before the width of the pressing bar is viewed, the printing machine should be allowed to stand still for about 20 seconds, and then the printing machine can be clicked to obtain a clear pressing bar again.
(3) The pressure between the plate roller and the fountain roller should be preferentially adjusted, and then the contact pressure between the plate roller and the printing plate should be adjusted, and then the pressure between the other ink rollers should be adjusted separately.
(4) Referring to the printing machine operation instructions, the pressure bar width between the ink rollers is generally 4 mm. However, for an ink roller having a small diameter and a good elasticity, the pressure bar width is preferably 3 mm; conversely, the pressure bar width is preferably 5 mm.
(5) The width of the pressure bar between the water rollers should be 5 to 6 mm. The pressure of the water roller on the metering roller should generally be such that the water film at both ends of the water roller has no obvious water droplets.
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