Monitoring of bearings with technical equipment and emergency replacement of bearings
The inner ring of the spherical roller bearing used on the paper machine is found to be damaged by the envelope detection method. The envelope signal spectrum between 0 and 200 Hz, below: intact bearing; above: damaged bearing nIR inner ring speed [min1] fIR inner ring signal frequency (cycle frequency) [Hz] 6: found by envelope detection method The inner ring of the spherical roller bearing on the paper machine is damaged. 0 4 8 12 16 20 min 24 The relationship between temperature change and vibration value and lubrication stop time. Spindle bearing B7216E.TPA; P/C u003d 0.1; n u003d 9000 min1; Fatigue damage of lubricant ISO VG100. Point-contact bearings (ball bearings) are the simplest; for roller bearings, complex evaluation procedures such as envelope circle detection can be used to reliably find the damage. However, this monitoring method is not suitable for observing the lubrication status. As mentioned above, problems with lubrication supply can be discovered through temperature detection. Figure 7 shows this very well. The vibration value is far less sensitive than the temperature sensor. Therefore, if conditions permit, it is ideal to use temperature measurement and vibration measurement to complement each other. 8: The development of fatigue failure of the inner ring raceway of angular contact ball bearings. From the occurrence of the failure, the time period for inspection is given as a percentage of the nominal life L10. Emergency bearing replacement program Once the remaining life of the bearing is detected to be damaged, the question that follows is to consider whether the bearing should be replaced immediately or can continue to be used until the next scheduled downtime of the machine. There are several bearing conditions that must be considered before making a decision. For example, bearing damage may reduce the working accuracy of the machine tool, so the urgency of bearing replacement mainly considers how long the parts without quality defects can continue to be produced. Of course, because the interruption of the oil supply system causes the bearing to lock up suddenly due to overheating at high speed, the bearing must be replaced immediately. In many cases, even though the bearings have been damaged, the machine tool can continue to operate without production quality problems. How long it can be used is related to bearing load, speed, lubrication and lubricant cleanliness. A large number of damage expansion tests under various loads have been carried out on ball bearings. Fatigue expansion is very slow under moderate loads, so under normal circumstances there is no need to replace the bearings before the next expected downtime. As the load increases, fatigue develops quickly. Fatigue begins to expand very slowly, but as the fatigue area increases, fatigue accelerates. Figure 8 (page 7), Figure 9 and Figure 10 show these findings. 9: After failure (when about 0.1% of the circumferential track is peeled off), the relationship between the size of the damaged area and the operating time 10: Until the circumferential track has B/ba damage, the average remaining after fatigue failure of the angular contact ball bearing The operating time is based on the relationship of stress conditions. Operating conditions before the first signs of fatigue failure: Elastohydrodynamic lubrication is the cleanest condition.