One failure of the main motor

Once, a four-color machine in a factory was the operator of the Heidelberg offset printing machine. The main motor of the offset press had a greater vibration than the original when the official printing was started. As a mechanic, I went for an inspection. At the scene, I felt that the vibration of the motor was enhanced compared to the original and that there was no abnormality in the sound of the bearing during motor operation. The motor load current was slightly larger than the normal condition. For comparison, the balance of the three-phase currents is within the normal range, and no faults have been found with the relevant electrical circuits and inspections. Then restart the operation and monitor the observation. After a shift operation, no other faults occurred. After the engine was shut down, the motor did not show any more vibration when it started to work on the next day.

But two days later, when one shift was produced, the vibration of the main motor appeared again. In order to find out the reasons, this time from the start of the machine to the stop of printing, the cleaning of the ink roller, the water roller, and the cleaning of the machine platform, I carefully observed every link, and discovered a problem: the individual operators of the shift were on the water. In the cleaning process of the roller and the ink roller, the process operation requirements are not strictly controlled, and in particular, the cleaning of the water roller is not clean and the work is done. Obviously, such an after-effect will have a bad effect on the operation of the motor because the ink on the roller surface is not cleaned cleanly and the ink on the surface of the residual roller is dried. Between the roller and the roller in the next shift The friction force generated by the contact operation is increased, and the ink used in the aluminized paper trademark print has a strong viscosity, and the resulting influence during the printing process is particularly pronounced. Because of the increase of friction, the load of the motor is correspondingly increased, and the increase of the load is manifested in the motor. In addition to the increase of the three-phase load current of the motor, the increase in vibration is also common.

Some of the main motors in use appeared to be operating normally. Some shifts showed relatively large vibrations. It was precisely because some shift operators were able to seriously wash and maintain the water rollers and ink rollers after the shift. The process discipline was implemented, and the roller cleaned complied with the quality requirements, so in the second day of production, there was no major motor vibration. On the contrary, there is a serious problem of motor vibration. In response to the problems and judgments found, the workshop conducted a process discipline education for operators to ensure the standardization of the use, cleaning, and maintenance of water rollers and ink rollers. The vibration of the main motor, which is affected by the poor cleaning and maintenance problems of the water roller and the ink roller, no longer occurs. This is a relatively special case that I encountered in the practice of repairing offset presses.