Analysis and treatment of abnormal noise of bearin

2022-08-05
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Analysis and treatment of abnormal sound fault of motor bearing

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analysis and treatment of abnormal sound fault of motor bearing

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the core lifting shape can be divided into different sizes: a high-voltage (6kV) motor YKK of feed pump, power 450KW, speed 2975r/min. Deep groove column nu3e222 bearing is used for shaft extension end. First, deep groove ball 6222 bearing is used for non load end. 1. abnormal sound of motor bearing

a high-voltage (6kV) motor YKK of feed pump, with power of 450KW and speed of 2975r/min. Deep groove column nu3e222 bearing is used for shaft extension end, and deep groove ball 6222 bearing is used for non load end. During operation, the sound at the shaft extension end is sharp and harsh, not like electromagnetic noise, nor like the sound of bearing oil shortage and dry grinding. The noise lasts for about 2min, and then intermittently for 2min. The vibration amplitude of the bearing measured by the vibration meter (va-80a) is 0.021mm. When the sound is abnormal, the measured vibration speed is 53.6m/s, sometimes even 97m/s, far exceeding the standard value of 28 m/s, and the current fluctuates greatly

due to the clearance fit adopted at the shaft extension end, the axial positioning dimension of the bearing cannot be adjusted. During the maintenance, it was found that there were uneven wear marks on the inner oil cover and two deep groove columns of the bearing were damaged. Measure the positioning dimensions of the bearing, end cap and inner and outer oil retaining small caps. After calculation, the allowable clearance of the bearing is 0.7mm. When the bearing temperature of the motor reaches 100 ℃, the expansion value of the bearing is about 0.9mm, which cannot meet the normal operation requirements of the motor. After replacing the deep groove column bearing for many times, the motor noise not only did not disappear, but also the abnormal sound cycle became 4min

2. Fault analysis and treatment

analysis according to the characteristics of the bearing: since the motor originally used Nu type deep groove column bearing, the motor is allowed to move axially. Both sides of the inner ring of the bearing have retaining edges, and the outer ring has no retaining edges. Therefore, the two-way displacement of the shaft relative to the bearing is allowed, and the elongation caused by the thermal expansion of the shaft can be withstood. At the same time, the clearance of the bearing is larger than that of the deep groove ball bearing, but the force on the bearing is linear, which is better than that on the point of the deep groove ball bearing. The motion track of the bearing is not a circle but an ellipse, which is caused by the gap between the dry deep groove column (or deep groove ball) and the raceway. The different forces during operation make the Motion Track elliptical. The bearing is mainly stressed at the lower part. For deep groove column bearings, the stress point is a straight line. During high-speed operation, due to the bearing clearance, the stress point changes, and the stress changes into a parabolic curve according to the design force movement track

during operation, the feed pump motor is mainly subject to axial force, and the driven load is stable. The necessity of allowable radial movement of deep groove column bearing is weakened. Therefore, the front bearing is replaced with deep groove ball bearing, and the bearing clearance is still C3, about 0.04mm, which can meet the operation requirements. At the same time, considering the expansion of the bearing, add a gasket with a thickness of about 0.8mm at the small cover of the oil retaining ring to overcome the movement caused by the temperature rise of the feed pump and the bearing

the micro surface curve of the bearing rolling element and raceway is rough and uneven, and certain impact will occur in the movement, but the pulse generated by this impact is high-frequency, so the parameter value of high-frequency interference measured by the vibration meter is larger than the standard. The deep groove column bearing has more contact with the raceway, resulting in large high-frequency impact. However, the contact between the deep groove ball bearing and the raceway is the point, resulting in relatively small high-frequency impact. Therefore, the motor in this example can use the deep groove ball bearing instead of the deep groove column bearing to solve the abnormal noise of the equipment

will the deep groove column bearing continue or terminate? Many interviewees believed that the abnormal sound of the bearing disappeared after the deep groove ball bearing was replaced. The noise did not appear again after a period of operation. The vibration amplitude of the measured motor was 0.013mm, and the acceleration value was 2.8m/s2. The load performance was stable, and the current did not fluctuate greatly

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