Periodic inspection of the hottest bearing II

2022-08-08
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Regular inspection of bearings (II)

III. bearing temperature

bearing temperature can be inferred from the temperature outside the bearing chamber. It is more appropriate if the oil hole can be used to directly measure the temperature of the outer ring of the bearing. Generally, the temperature of the bearing rises slowly with the operation and reaches a stable state after hours. The normal temperature of the bearing varies with the thermal capacity, heat dissipation, speed and load of the machine. If the lubrication and installation parts are appropriate, the bearing temperature will rise sharply, and abnormal high temperature will occur. At this time, the operation must be stopped after finishing the truth, and necessary preventive measures must be taken. According to a large number of test data, the table lists the average value of the outer ring temperature of the bearing in various machines for reference. Since the temperature is affected by lubrication, speed, load and environment, the value in the table only represents the approximate temperature range. The thermal sensor can be used to monitor the working temperature of the bearing at any time, and automatically alarm or stop when the temperature exceeds the specified value to prevent the occurrence of combustion shaft accidents

IV. lubrication

1. The role of bearing lubrication

lubrication has an important impact on the fatigue life, friction, wear, temperature rise, vibration, etc. of rolling bearings. Without normal lubrication, the bearing will not work at the extra cost when it is checked out. Analysis of the causes of bearing damage shows that about 40% of bearing damage is related to poor lubrication. Therefore, good bearing lubrication is an effective measure to reduce bearing friction and wear

in addition, bearing lubrication has many functions, such as heat dissipation, rust prevention, sealing, impact mitigation, etc. the functions of bearing lubrication can be briefly described as follows:

a. an oil film is formed between the two rolling surfaces or sliding surfaces in contact with each other to separate the two surfaces and reduce the friction and wear of the contact surfaces

the evening of May 27 B. when oil lubrication is used, especially when circulating oil lubrication, oil mist lubrication and oil injection lubrication are used, the lubricating oil can take away most of the friction heat inside the bearing and play an effective role in heat dissipation

c. when grease lubrication is used, it can prevent foreign matters such as external dust from entering the bearing and play a sealing role

d. lubricants can prevent metal corrosion

e. prolong the fatigue life of bearing

2. Comparison between grease lubrication and oil lubrication the lubrication methods of bearings are roughly divided into grease lubrication and oil lubrication. In order to give full play to the function of the bearing, it is important to adopt the lubrication method according to the use reduction and use purpose. Indicates, for example, the advantages and disadvantages of grease lubrication and oil lubrication in the prototype model of functional materials or flame retardant materials with required specific strength

3. Grease lubricating grease is a lubricant composed of base oil, thickener and additives. When selecting, the lubricating grease that is very suitable for the service conditions of the bearing shall be selected. Due to different trademarks, there will be great differences in performance, so attention must be paid to the selection. Common lubricating greases for bearings include calcium base grease, sodium base grease, calcium sodium base grease, lithium base grease, aluminum base grease, molybdenum disulfide grease, etc. The amount of grease filled in the bearing shall be 1//3 to fill the internal space of the bearing. It shall be reduced to 1/3 at high speed. Excessive grease increases the temperature

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