There are tips for maintaining rubber rollers.

The rubber roller, as one of the important components of the offset printing machine, is closely related to the quality of the printed product. Therefore, it is very important to use and maintain the rubber roller scientifically and correctly. Taking a 4-color offset printing machine as an example: the total value of the set of water and ink rollers for the four color groups of this machine is about 50,000 yuan. If carefully maintained and scientifically adjusted, its average service life can reach 2 years; if used improperly, its average service life will be shortened to 1 year or half a year. Therefore, strengthening employees' sense of responsibility and improving their operating skills are of great significance for ensuring product quality, reducing maintenance costs, improving economic benefits, and promoting enterprise development.

Analysis of the causes of abnormal damage to the rubber roller

According to the author's years of practical experience, the causes of abnormal damage to the rubber roller generally include the following.

(1) During installation and disassembly, if not handled gently, the roller body or rubber surface may be damaged.

(2) The fit between the rubber roller shaft head and the bearing is not tight, or the bearing performance is poor, causing the rubber roller to be subjected to friction and compression, which can accelerate the cracking and aging of the rubber roller.

(3) Excessive accumulation of impurities such as ink skin and ink residue on the rubber roller accelerates friction and aging between the rubber rollers, causing the surface of the rubber roller to be filled with pockmarks, making it unable to accurately transfer water and ink.

(4) Improper choice of cleaning agents for the rubber roller, such as gasoline, reducing agents, strong acids, strong alkalis, etc., can cause cracking and flaking of the rubber surface of the rubber roller.

(5) Excessive pressure between the rubber rollers causes deformation due to compression, heating and expansion of the rubber, leading to direct peeling from the iron core of the rubber roller, resulting in the rubber roller being scrapped.

(6) High workshop temperatures prevent the rubber roller from dissipating heat in a timely manner during operation, causing the internal temperature of the rubber to continuously rise and accelerating rubber aging.

(7) Ink drying too quickly and severe emulsification can continuously accumulate at both ends of the rubber roller, thereby indirectly increasing the pressure at this point, accelerating its wear and aging.

(8) The ink release keys at both ends of the ink fountain are stuck, causing the rubber roller at both ends to not receive ink replenishment, resulting in the rubber roller being in a state of dry friction and damage.

(9) In multi-color printing machines, due to a low number of colors for a certain print, the rubber rollers of other color groups may run idle for a long time, causing them to be in a state of dry friction and damage.

(10) If the printing plate is not tightened or the plate clamp is not secure, the dragging part of the printing plate may frequently break. When the rubber roller operates close to the printing plate cylinder, the rubber surface of the rubber roller will be scratched, leading to the rubber roller being scrapped.

(11) Improper storage of the rubber roller, such as not avoiding light, can lead to damage from compression or scratches from sharp objects.

There are many other causes of abnormal damage to the rubber roller, but as long as careful analysis is conducted to identify the root of the problem, damage to the rubber roller can be avoided.

Correct usage methods for the rubber roller

1. Correctly install the rubber roller bearing

First, clean both ends of the rubber roller, then select bearings that meet the specifications and models required by the machine design, and evenly apply a layer of lubricating oil on all mating surfaces. Then, use a special sleeve for installing the bearing to apply even force, ensuring it is installed smoothly. Avoid applying direct force on the bearing surface to prevent damage.

2. Standardize the adjustment of pressure between the water and ink rollers

During the printing process, the water roller and ink roller must continuously and evenly provide an appropriate amount of water and ink to the printing plate to achieve consistent ink color in the printed product. Therefore, appropriate pressure must be maintained between the rubber rollers and between the rubber roller and the printing plate to ensure good ink transfer. To ensure the pressure between the water and ink rollers, the method of roller width should be used, which mainly includes the following points.

(1) Evenly add an appropriate amount of yellow ink to the clean rubber roller, then operate the machine to evenly distribute the ink on the surface of the ink roller.

(2) Jog the printing machine to check the roller width. It is worth noting that before checking the roller width each time, the printing machine should be stopped for about 20 seconds, and then jogged again to obtain a clear roller width.

(3) The pressure between the ink roller close to the plate and the ink roller should be adjusted first, then the contact pressure between the ink roller and the printing plate should be adjusted, and finally, the pressure between other ink rollers should be adjusted.

(4) According to the printing machine operation instructions, the roller width between ink rollers is generally suitable at 4mm. However, for smaller diameter and more elastic ink rollers, a roller width of 3mm is preferable; conversely, a roller width of 5mm is preferable.

(5) The roller width between water rollers should be suitable at 5-6mm. The pressure of the water roller on the metering roller should be such that there are no obvious water droplets on the water film layer at both ends of the water roller.

(6) After adjusting the pressure of all water and ink rollers, the adjustment screws should be fixed in time to prevent them from shifting after the printing machine rotates.

3. Correctly disassemble the rubber roller

Each time the rubber roller is disassembled, employees should coordinate to loosen the adjustment screws by 2 turns. When reinstalling the rubber roller, simply tighten it in the reverse direction by 2 turns. Even if there is an error, it can be quickly resolved. Additionally, each bearing's quality should be checked; if there is any wobbling or obstruction, it must be replaced immediately.

Correct maintenance methods for the rubber roller

1. Ensure lubrication of all shaft sleeves and shaft seats

In actual work, the water roller seat and ink roller seat are often severely worn, and broken bearings can damage the roller and cause greater losses. Therefore, before installing all rubber rollers, lubricate the bearings, shaft sleeves, shaft seats, and brackets on both sides of the rubber roller to minimize the friction force on the inking roller caused by the back-and-forth movement of the ink roller and its friction on the bearing seat.

2. Maintenance of rubber rollers in each color group of the printing machine.

2.印刷机各色组胶辊的保养

The diameter of any printing machine's rubber roller gradually decreases after 2 to 3 months of use, which affects the accurate transfer of water and ink. At this time, the rubber rollers of each color group of the printing machine should be maintained in sequence, and the pressure between the rubber rollers should be readjusted.

3. Cleaning of the rubber rollers

Rubber rollers should have good ink absorption and transfer properties, and generally, high-quality rubber rollers have a fine and smooth surface. However, since rubber rollers are in contact with water, ink, paper, and other materials for a long time, it is inevitable that residues will accumulate on the rubber rollers. Although they should be cleaned thoroughly each time, some residues cannot be completely washed away. Over time, a smooth crystalline layer similar to calcium will form, firmly adhering to the surface of the rubber roller, blocking its capillaries, causing it to lose elasticity and become harder, severely affecting ink and water transfer performance, thus making it impossible to stabilize the ink color of the printed products.

Currently, although many companies have developed fountain solutions to prevent the calcification of rubber rollers, and the results are good, the Price is relatively high, and they cannot be widely adopted. To solve this problem, printing companies should regularly use specialized cleaning pastes and cleaning water to clean the rubber rollers, but this method is time-consuming and labor-intensive, which inadvertently increases production costs. Therefore, I believe a better method is to wash the rubber rollers with a small amount of citric acid water after each cleaning, causing some calcium impurities on the surface to undergo a chemical reaction, and then clean them again.

Some people believe that being so careful in using and maintaining rubber rollers wastes a lot of time, not realizing the ancient saying "Sharpening the knife does not delay the work of chopping wood" and the principle of "Practice makes perfect." As long as standardized operations are consistently adhered to over the long term, and technical skills are continuously improved, it can naturally simplify the process, greatly reducing the labor hours consumed, allowing for more efficient use of rubber rollers.