Rubber roller use precautions (2)
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Use
1. Requirements for the environment of the rubber roller
Printing production in a humid, humid, dusty environment, coupled with high-speed operation of the machine, will increase the surface temperature of the rubber roller, expand the colloid, increase the friction of the rubber roller, affect the product quality, and shorten the service life of the rubber roller.
Conditional printing companies, the offset printing workshop should install air conditioning, and keep the workshop clean and clean.
2. Problems that should be paid attention to in printing production
(1) boot
It must be turned on with ink. If it is not used, it is necessary to add lubricant. The water roller should also be operated with water, and it must not be “dry-grinded”. Otherwise, the rubber roller will be quickly scrapped.
(2) Long downtime
The ink roller is pressed at a certain fixed position, so that there is a possibility of partial depression. At this time, it is best to remove the ink roller and clean it on the ink tray for use. Do not place it directly on the table to prevent partial deformation of the rubber roller.
(3) Aging rubber roller
The rubber roller is used for a long time and aging, coupled with the erosion of chemicals, causing the rubber to lose the "slag". Such a rubber roller is preferably updated in time to avoid seriously affecting the quality of the printed product.
(4) The production environment temperature is too low
At this time, the ink is not easy to be evenly mixed, and an auxiliary material may be appropriately added to the ink, and it is strictly prohibited to use an infrared heater to bake the ink roller.
(5) Sundries
During the printing operation, the offset printing machine should be kept clean and tidy. The tools such as the ink shovel and the printing supplies cannot be randomly placed. Moreover, the debris and the ink lumps cannot be clamped into the ink roller to scratch and crush the ink roller.
3. Problems and treatment of rubber roller in the printing process
(1) Surface crystallization and calcification of rubber roller
The surface of the high-quality rubber roller should be fine and smooth, with a slight viscous hand and good ink transfer performance. In production, the rubber roller is affected by the factors such as dampening solution, ink and paper for a long time. In addition, it is impossible to thoroughly clean each time. The residual impurities are deposited on the surface of the rubber roller layer by layer. Over time, the surface of the rubber roller will be closed. The capillary pores form a smooth crystalline layer similar to calcium, which seriously affects the ink transfer and water transfer performance, and cannot stably control the ink color of the print. In this case, after washing with the car wash water, it can be washed again with some citric acid water to chemically react some calcium impurities on the surface of the rubber roller to form a soluble substance for cleaning.
(2) The surface of the rubber roller is easy to be scratched and numb
Because the rubber roller is relatively soft, a slight hard object will be scratched during high-speed operation. In particular, the alcohol dampening solution relies on the plate water roller, and once scratches occur, it can no longer be used. In order to avoid such failures, the first is to check whether the plate is tightened or the clamp is clamped, so that the cracks and cracks at the printing plate tip are scratched by the plate water roller and the ink roller; the second is to see if the ink roller maintenance is not timely. The impurities such as ink, ink residue and the like are accumulated, which accelerates the friction, heat generation and aging of the rubber roller, and causes the surface of the rubber roller to be covered with numbness. In this case, the rubber roller is generally severe at both ends.
(3) Premature cracking and aging of the rubber roller
There are many reasons, such as excessive dry oil in the ink, so that the ink is dry on the rubber roller; the cleaning agent used for cleaning the rubber roller is improperly selected, the cleaning time is too rushed, and the impurities on the rubber roller cannot be thoroughly cleaned; the ambient temperature of the workshop Higher, the dampening cooling system works poorly, the large amount of heat generated during the operation of the rubber roller can not be dissipated in time, the internal temperature of the rubber roller is high; the performance of the rubber roller bearing is not good, and it is rotated by the ink roller, which generates jumping friction, extrusion, etc. .
(4) Deinking
In the offset printing operation, the ink is emulsified due to "large water and large ink", and a hydrophilic foundation is formed on the smooth rubber roller, and deinking phenomenon occurs. The solution is to shovel the emulsified ink, wash the deinking roller with gasoline, mix the surface with a 5% aqueous solution of sodium hydroxide and talc, remove the hydrophilic layer, and restore the oleophilic properties of the ink roller. At the same time, the metal roller (or hard roller) is also treated accordingly. The hard roller can also be sanded with fine water sand in the state of water drenching, and it should not be fixed at the same part, otherwise the rubber roller will be damaged. The fundamental method is to control the pH value of the water hopper, do a good job of water and ink balance, and reduce the emulsification of the ink.
Maintenance
Whether the maintenance of the ink roller is reasonable and in place has a direct impact on the service life of the ink roller and the printing quality.
1. Regular maintenance
After each printing, the ink, paper powder and paper wool remaining on the rubber roller should be cleaned. Special attention should be paid to cleaning and wiping the residue at both ends of the rubber roller to avoid long-term accumulation of residue, which causes the rubber roller to aging and crack at both ends. . The cleaning agent must use the specified chemical reagents, and must not use corrosive solvents; the cloth is preferably knitted with a cloth to prevent cotton residue.
Check whether the bearings at both ends of the rubber roller are freely movable and in good condition. If loose or worn, tighten or replace them in time. When the bearing of the rubber roller is damaged to a certain extent, it will generate the jumping friction and extrusion, shorten the service life of the rubber roller, and cause the printed product to have an "ink/water bar". The rubber roller should be taken down every week to butter the bearing and replace the bearing with severe wear and poor rotation to ensure the normal use of the rubber roller.
Check if the rubber on the surface of the rubber roller is good, especially the plate rubber roller must choose the best. For rubber sheets with cracks and more eyes on the surface, it should be re-polished and replaced in time.
2. Rotation maintenance of multi-color group
In the weekly maintenance, it is difficult to carry out thorough and thorough maintenance of the multi-color platform offset press or the rotary machine. Under the premise of normal day maintenance, according to the structural characteristics of the multiple color unit of the equipment, the monthly maintenance and the half-year maintenance are carried out. The project is broken down to weekly, with one print unit being focused on each week. This method is also used for the maintenance of the rubber roller of each color group. Every week, all the ink rollers of one color unit are inspected and maintained, and the rubber roller is mainly checked for calcification, whether the bearing is short of oil, and whether the pressure between the rubber rollers is to be adjusted.
In this month, all the rubber rollers of the whole machine can be rotated at least once. The machine is running normally for about half a year, and then check the maintenance manual for any maintenance contents.
When the color group is rotated and maintained, the personnel should have a reasonable division of labor, cooperate with each other to be tacit, the movement should be standardized, and various tools and detergents should be selected appropriately. Neither the sharp tool can be used to shovel the roller or the rubber roller, nor can the reducing agent and banana be used. Water cleaning rubber rollers, etc.; also make detailed records, including the main parts of maintenance, maintenance methods, hidden dangers found, maintenance plans, etc. Under special circumstances, work that cannot be completed this week should be scheduled in the next week's maintenance schedule to ensure that the maintenance parts are implemented one by one.