Inspection and fault handling in bearing operation
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| Time：2016.09.05 News Sources：Shandong Xinkaite bearing Co.,Ltd. Views：
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Operation inspection items bearing rolling sound, vibration, temperature, lubrication status, as follows:
First, the sound of the rolling bearing
Using sound measuring device for operation of the bearing rolling sound size and quality inspection, bearing even a slight peeling damage, abnormal tone and irregular tone will be issued with a sound measuring device capable of resolving.
Second, the vibration of the bearing
Bearing vibration of the bearing damage is very sensitive, such as peeling, indentation, corrosion, cracks, wear, etc. will be reflected in the bearing vibration measurement, therefore, through the use of special bearing vibration measuring device (frequency analyzer, etc.) to measure the vibration the size, frequency can not be inferred by the abnormal situation. The measured values due to the conditions of use or the sensor mounting position of the bearing, etc., and thus requires prior measurement value each machine is determined after analysis and comparison criteria.
Third, the temperature of the bearing
Bearing temperature, generally room temperature outside the bearing can be inferred, the hole can be measured directly if the use of the bearing outer ring temperature, it is more appropriate position. Generally, the bearing temperature rise slowly as the start of the operation, after 1-2 hours to reach steady state. The normal temperature of the bearing due to heat capacity, heat capacity, speed and load of the machine is different. If the lubrication, install the appropriate department, the bearing temperature will be rapid rise, there will be abnormal high temperature, then must stop running, take the necessary precautions. According to a large number of test data, Table 4-1 lists the average value in a variety of mechanical work bearing outer ring temperature, for reference. Since the lubricating temperature, speed, load, by the environment, values in the table represent only approximate temperature range. You can always use the thermal sensor to monitor bearing operating temperature, and automatic alarm or stop the user to prevent burning shaft accident occurred when the temperature exceeds a predetermined value.
Fourth, lubrication
(A) the role of bearing lubrication
Lubrication rolling bearing fatigue life and friction, wear, temperature, vibration, etc. have a major impact, not normal lubrication, bearings will not work. Analysis shows that the reasons for bearing damage, bearing damage and about 40% are related to poor lubrication. Therefore, bearing good lubrication is an effective measure to reduce the bearing friction and wear. In addition, bearing lubrication as well as cooling, antirust, seal, and other action to ease the impact, the role of bearing lubrication can be briefly described as follows:
a. between the sliding surface of the titanium surface or rolling contact with each other to form a film a second surface spaced from the contact surface to reduce friction and wear.
When b. When using oil lubrication, especially the use of circulating oil lubrication, oil mist lubrication and injection lubrication, the lubricating oil can take away most of the heat inside the bearing friction, play an effective heat sink.
c. When using grease lubrication, prevents external dust and other foreign matter from entering the bearings, play a role in the closure.
d. prevent metal corrosion lubricant has a role.
e. extend the fatigue life of the bearing.
(Ii) comparison of grease and oil lubrication
Bearing lubrication method is roughly divided into two kinds of lubricating grease and oil. To maximize the function of the bearings, it is important to use according to the purpose of use and Tiaojian used lubrication method. Table 4-2 shows the grease and oil lubrication advantages and disadvantages.
(C) greased
Grease is the lubricant base oil, a thickener and additive composition. When selected, you should select well suited to the conditions of use of the bearing grease run, due to the different brands, the performance will also be very different, so the choice of the time, we must pay attention to. Bearing grease commonly used calcium-based grease, grease, sodium, calcium and sodium based grease, lithium grease, aluminum grease and molybdenum disulfide grease. Number of bearing grease filling, to fill the space inside the bearing 1 / 2-1 / 3 as appropriate. Should reduce speed to 1/3. Excessive grease the temperature rises.
(Iv) grease selection
When working temperature is selected in accordance with the grease, the main indicators should be dropping point, oxidation stability and low temperature performance, dropping point temperature is generally used to evaluate the performance of the bearing should be less than the actual operating temperature dropping point 10-20 ℃. Synthetic grease dropping point temperature should be below 20-30 ℃. According to the load bearing grease selection of heavy-duty should be selected small grease penetration. In addition to the penetration of small, but also has a high film strength and extreme pressure properties while working under high pressure. According to the environmental conditions when selecting grease, calcium-based grease easily soluble in water, suitable for drying and less water environment.
(V) oil lubrication
At high speed, high temperature conditions, for grease lubrication oil lubrication can no longer meet. By circulating lubricating oil, it can take away a lot of heat.
Viscosity is an important characteristic of the lubricating oil, the viscosity directly affects the size of the oil film thickness between mobility and surface friction lubricant formed at the bearing operating temperature viscosity of the oil is generally 12-15cst. The higher the speed should be selected low viscosity, load more weight should be selected higher viscosity. Commonly used mechanical lubricant oil, high-speed mechanical oil, turbine oil, compressor oil, transformer oil, cylinder oil.
Oil lubrication method comprising:
a. Oil bath lubrication
Oil bath lubrication is the most common method of lubrication, suitable for low and medium-speed bearing lubrication, part of the bearing is immersed in the tank, lubricating oil by the rotating bearing parts brought up, and then flows back into the oil tank should be slightly less than the minimum rolling central body.
b. drip lubrication
Drop lubrication suitable lubricants have required dosing bearing member, drip every 3-8 seconds to drop the amount is generally appropriate, too much oil will cause the bearing temperature increased.
c. circulating oil lubrication
The filtered oil pump oil to the bearing member through the bearing lubricant filtered again after cooling after use. As the circulating oil can take some heat, bearing cooling, therefore the method is suitable for high speed bearing member.
d. Spray lubrication
With dry compressed air sprayer and mixed to form a lubricating oil mist, spray bearings, air can effectively cool the bearing and to prevent intrusion of impurities. This method is suitable for high-speed, high-temperature lubrication of the bearing member.
e. spray lubrication
The high-pressure oil pump oil through the nozzle hitting the bearings, bearing the incident through the other end of the bearing oil flowing into the oil sump. When the bearing is rotating at high speed, the rolling elements and cages are also at a relatively high rotational speed of the surrounding air stream is formed, it is difficult with the general method of lubricating the lubricating oil to the bearings, the lubricating oil must then sprayed with a high pressure jet method to the bearing, the position of the nozzle should be placed between the inner ring and the cage holding center.
(Vi) a solid lubricating
In some special conditions, a small amount of solid lubricant added grease, as No. 13 was added to 5% molybdenum disulfide to reduce wear and improve compressive heat resistance, high temperature for elegant, high vacuum, corrosion-resistant , anti-radiation, as well as very low temperature, and other special conditions, the solid lubricant is added to plastic or powder metallurgy materials, it can be made with self-lubricating properties of the bearing parts, such as by adhesive bonding in the solid lubricant raceway, the cage and rolling elements, to form a lubricating film, reducing friction and wear have a certain effect.
(Vii) lubricants and replacement supplement
a. supplementary grease intervals
Due to the increased mechanical action, aging and pollution, the bearing arrangement filled lubricating base will gradually lose its lubricating properties. Therefore, the need for lubrication rank constantly replenished and updated. Lubricants will complement the interval due to the formation of the bearing, the size and speed, etc., and need to be supplemented in accordance with the operating time interval substantially grease. In addition, when the temperature exceeds 70 ℃ lower bearing case, bearing temperature rise 15 ℃, then use complementary grease intervals reduced by half. Sided enclosed bearing grease has been loaded at the time of manufacture, "HRB" used in these products are standard grease, total operating temperature range and other properties suitable for the provision of the occasion, and the corresponding amount of grease filling the bearing size, life of fat generally exceeds bearing life, except for special occasions, without added grease.
b. oil change intervals
Oil change intervals due to different conditions of use and oil, under normal circumstances, the operating temperature of 50 ℃, when the good little dusty environments, replaced once a year, when the oil temperature reaches 100 ℃, to 3 months or less replacement.
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