Once, the operator of a four-color four-open Heidelberg offset printing machine at a certain factory reported that the main motor of the offset printing machine had greater vibration than the original one when starting the official printing. As a mechanic, I went to the inspection. At the scene, I felt that the vibration of the motor is stronger than the original one through observation and touch. Listening to the noise of the bearing during the operation of the motor is no exception, and the load current of the motor is slightly larger In comparison, the balance of the three-phase current is within the normal range, and no faults have been found in the related electrical circuits and inspections. So restart the operation, and monitor and observe. After one shift operation, no other faults occurred. After the shutdown, the motor no longer experienced large vibrations when it went to work the next day.
But two days later, when there was a shift production, the vibration abnormality of the main motor appeared again. In order to find out the reason, from the start to the stop of printing this time, I carefully observed every link of the ink roller, water roller cleaning and machine cleaning after printing, and found a problem: individual operators of this shift were There is no strict control of the process operation requirements during the cleaning of the roller and ink roller, especially the cleaning of the water roller is not clean, which is a hassle. Obviously, the remaining troubles like this will have a bad influence on the operation of the motor, because the sticky ink on the surface of the roller is not cleaned cleanly, and the residual ink on the surface of the roller is dry, between the roller and the roller in the next shift of production The friction generated by the contact operation is increased, and the ink used in the printing of the aluminum-coated paper trademark has a strong viscosity, and the resulting impact during the printing process is particularly obvious.
Because of the increase in friction, the load of the motor is increased accordingly. The increase in load is manifested in the motor. In addition to the increase in the three-phase load current of the motor, the increase in vibration is also common. Some of the main motors in use this time appear to be operating normally, and some of the shifts show relatively large vibrations, precisely because some shift operators can be serious in the cleaning and maintenance of the water roller and ink roller after the shift. The process discipline is enforced and the cleaned rollers meet the quality requirements, so in the production of the next day, there will be no major vibration of the main motor. On the contrary, there is a problem that the motor vibrates greatly. In response to the problems and judgments found, the workshop conducted technical discipline education for the operators to ensure the standardization of the use, cleaning and maintenance of water rollers and ink rollers. The vibration of the main motor affected by the problems of cleaning and maintenance of the water roller and ink roller will no longer occur. This is a special case I encountered in the practice of repairing offset presses.
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