1. Excessive pressure between the rubber rollers will increase the friction between the rubber rollers, heating the rubber rollers, increase the squeezing and expansion between the rubber rollers, accelerate the aging and deformation of the rubber rollers, accelerate the emulsification process of ink and water, which is not conducive to Ink transfer. The solution is that the pressure between the rubber rollers should be basically the same as the pressure on the contact plate. The experience is that inserting 1500 steel wires and a 3 cm wide plug between the rubber rollers can feel a certain tightening force.
After scrubbing, wipe again with a clean cloth, and then install the rubber roller on the machine for next use.
2. Crystallization treatment on the surface of the rubber roller. Surface crystallization will close the pores on the surface of the rubber roller, causing the rubber roller to lose ink affinity, resulting in uneven ink transfer and emulsification.
The solution is: unload the rubber roller on the machine, place it flat on the shelf, stick kerosene and pumice powder with a cloth, wipe the surface of the rubber roller evenly, wipe the crystal layer on the surface of the rubber roller clean, revealing the rubber of the original rubber roller Then use car wash water or gasoline to clean the residual kerosene and pumice powder on the rubber roller, reinstall and adjust the pressure of the rubber roller. When the machine is running at high speed, the bearing on the rubber roller is obviously worn, especially when the operator usually pays attention to the bearing maintenance cloth. When the rubber roller bearing is damaged to a certain extent, the rubber roller will be bounced, friction and squeezed, shorten the service life of the rubber roller, and cause the phenomenon of “ink streaks and water streaks” in the printed matter. Therefore, the operator is required to remove the rubber rollers, lubricate the bearings, and replace the severely worn and poorly rotating bearings to ensure the normal use of the rubber rollers.
3. In the hot and humid weather and the surrounding dust production environment, due to the impact of the rubber roller accumulation in the workshop environment, the high-speed operation of the machine makes the surface temperature of the rubber roller continue to rise, the rubber roller is heated to expand, and the friction of the rubber roller increases, thereby shortening the rubber roller. The service life of the roller.
Therefore, in qualified factories, offset printing inserts need to be equipped with air conditioning to keep the workshop clean and tidy, so that the machine can be produced and run in a good environment. Only in a good workshop environment can high-quality products be produced.
When preparing silicone rubber rollers, rubber rollers and crutches accessories, the appropriate raw rubber should be selected according to the requirements of the use conditions. The physical properties of the rubber outside the rubber roller can be further adjusted by various reinforcing agents and plasticizers. The following introduces the characteristics of several commonly used rubber rollers and their applications on the rubber rollers ① Neoprene: suitable for making flexible printing rubber rollers, photogravure printing rubber rollers, etc. The rubber roller can be molded, film wrapped, wound or extruded. Due to the poor storage stability of rubber, care should be taken to avoid parking under direct sunlight during the manufacturing process. At the same time, the temperature conditions of the parking rubber should be controlled.
② Nitrile rubber: used to make printing rubber rollers, food industry rubber rollers, textile printing and dyeing rubber rollers, soft rubber rollers in contact with solvents, etc. Nitrile rubber has poor ozone resistance and should not be operated in an environment with high ozone concentration. Nitrile rubber and PVC can be used together to obtain rubber with good ozone resistance and weather resistance. ③ Polyurethane rubber: excellent tensile strength, abrasion resistance and crack resistance. Polyester polyurethane rubber has good resistance to multiple solvents. In addition, the compound’s continuous exposure to high temperature and humidity can also adversely affect its performance. The key to the polyurethane rubber roller under high speed and high pressure is to improve its dynamic roll-off and cracking. ④ Silicone rubber: heat resistance up to 200-250 degrees, good chemical resistance, the main disadvantage is low tensile strength. Typical uses of silicone rubber rollers include fabric heat setting, plastic heat setting, embossing and calendering, and copier fixing. The molded silicone rubber roller is wrapped by a film. Because of its low strength, operation must be careful. ⑤ Chlorosulfonated polyethylene; it has high toughness, high elasticity, abrasion resistance, heat resistance up to 150 degrees, good resistance to various chemicals, oil resistance and insulation. In addition to casting methods, it can also be manufactured by a variety of methods. The rubber should be protected from sunlight during the production process. ⑥ Ethylene-propylene rubber: It can be used at a high temperature of 150°C. It has good chemical resistance and polar solvent resistance, but it is not resistant to hydrocarbon solvents and oil. The utility model can be used to make the extrusion rubber roller, the conveying rubber roller and the printing rubber roller contact the ink containing acetone and ester solvent. The roll can be wrapped and squeezed. During the process operation, take care to avoid contact with oil and hydrocarbon solvents.
