Inspection and troubleshooting of bearings in operation

The inspection items in operation are rolling sound, vibration, temperature, lubrication status of the bearings, etc. The details are as follows.

I. Rolling sound of bearings

The size and sound quality of rolling sound of bearings in operation are checked by using microphone. Even if there is slight damage such as stripping of bearings, abnormal sound and irregular sound will be issued, which can be distinguished by microphone.

Second, vibration of bearings

Bearing vibration is sensitive to bearing damage, for example, peeling, indentation, rust, crack, wear and so on will be reflected in bearing vibration measurement, so the size of vibration can be measured by using special bearing vibration measuring device (frequency analyzer, etc.), and the specific situation of abnormality cannot be inferred by frequency division. The measured value varies depending on the conditions of use of the bearing or the location of the sensor installation, so it is necessary to analyze and compare the measured value of each machine in advance to determine the judgment criteria.

Third, the temperature of the bearing

Bearing temperature, generally have bearing room outside the temperature can be inferred, if the use of oil holes can be directly measured bearing outer ring temperature, it is more bit appropriate. Usually, the temperature of the bearing starts to rise slowly with operation and reaches a stable state after 1-2 hours. The normal bearing temperature varies depending on the heat capacity, heat dissipation, speed and load of the machine. If the lubrication and mounting section are appropriate, the bearing temperature will rise sharply and abnormally high temperatures will occur, at which time the operation must be stopped and necessary precautions taken. According to a large number of test data, Table 4-1 lists the average value of the outer ring temperature when the bearings are working in various machines for reference. Since the temperature is affected by lubrication, speed, load and environment, the values in the table only indicate the approximate temperature range. The use of heat sensors can monitor the working temperature of the bearing at any time, and realize the temperature exceeds the specified value when the automatic alarm households or stop to prevent the occurrence of shaft burning accidents.

Four, lubrication

(A) the role of bearing lubrication

Lubrication of rolling bearing fatigue life and friction, wear, temperature rise, vibration and other important impact, no normal lubrication, the bearing can not work. Analysis of the causes of bearing damage shows that about 40% of bearing damage are related to poor lubrication. Therefore, good lubrication of the bearing is an effective measure to reduce friction and wear of the bearing. In addition, bearing lubrication and heat dissipation, rust prevention, sealing, mitigation of impact and other roles, bearing lubrication can be briefly explained as follows.

a. In mutual contact between the two rolling surface or sliding surface to form a layer of oil film between the two surfaces, reduce the contact surface friction and wear.

b. When using oil lubrication, especially when using circulating oil lubrication, oil mist lubrication and oil spray lubrication, lubricating oil can take away most of the frictional heat inside the bearing and play an effective role in heat dissipation.

The filtered oil is delivered to the bearing parts by oil pump, and the lubricant after passing the bearing is filtered and cooled again and then used. As the circulating oil can take away certain heat to cool down the bearing, so this method is suitable for the bearing parts with higher speed.

d.Spray lubrication

Using dry compressed air through the sprayer and lubricant mixture to form oil mist, spray bearing, airflow can effectively make the bearing cooling and can prevent the intrusion of impurities. This method is suitable for high-speed, high-temperature bearing parts of the lubrication.

e.Jet lubrication

The oil pump will shoot high-pressure oil into the bearing through the nozzle, and the oil shot into the bearing will flow into the oil tank through the other end of the bearing. In the bearing high speed rotation, rolling body and cage also with a fairly high rotation speed to make the air around the formation of airflow, with the general lubrication method is difficult to lubricant to the bearing, then must use high pressure injection method will lubricant spray to the bearing, the nozzle position should be placed in the inner ring and cage center between.

(F) solid lubrication

In some special use conditions, add a small amount of solid lubricant into grease, such as adding 3~5% of No.1 molybdenum disulfide can reduce the wear and tear, improve the resistance to pressure and heat, for high temperature, elegance, high vacuum, corrosion resistance, radiation resistance, and very low temperature and other special conditions, add solid lubricant into engineering plastic or powder metallurgy material, can make bearing parts with self-lubricating performance, such as using binder to Solid lubricant is bonded on the raceway, cage and rolling body to form lubricating film, which has certain effect on reducing friction and wear.

(G) Lubricant replenishment and replacement

a. The interval of grease replenishment

Due to mechanical action, aging and pollution increase, bearing configuration filled with lubricating base will gradually lose its lubricating properties. Therefore, the lubricating order needs to be constantly replenished and updated. The interval time of lubricant replenishment will be different depending on the formation, size and speed of the bearing, etc. The approximate interval time of grease replenishment is needed according to the running time. In addition, when the bearing temperature exceeds 70℃, every 15℃ rise in bearing temperature, the grease replenishment interval time should be reduced by half.

Double-sided closed bearing in the manufacture has been loaded with grease, "HRB" in these products are used in the standard grease, a total operating temperature range and other performance suitable for the specified occasions, and the amount of grease filling also with the size of the bearing corresponding, grease life can generally exceed the bearing life, except for special occasions, do not need to replenish the grease.

b.Lubricant replacement cycle

The replacement cycle of lubricating oil is different due to the use conditions and oil quantity, etc. Generally, when the operating temperature is below 50℃ and used in a good environment with little dust, it should be replaced once a year, and when the oil temperature reaches 100℃, it should be replaced once in 3 months or shorter.