Bearing lubrication is to enable the bearing to run normally, avoid direct contact between the raceways and the surface of the rolling body, reduce the friction and wear inside the bearing, extend the service life of the bearing, enhance the performance of the bearing, and at the same time, to prevent the bearing from rust and corrosion caused by foreign matter invading the bearing.
This paper introduces 11 common lubrication methods for bearings, hoping to help you.
Manual lubrication
This is the most primitive method, in the case of insufficient lubricating oil bearing, the oiler to supply oil.
But this method is difficult to maintain a certain amount of oil, because of negligence to forget the greater risk of refueling, usually only used for light load, low speed or intermittent movement of the occasion, the best time to operate, in the refueling hole set dust cover or ball valve, with felt, cotton, wool as a filter device.
Drop point lubrication
It is usually used for light and medium load bearings with a peripheral speed of less than 4 ~ 5m/s to supply approximately quantitative lubricating oil through holes, needles, valves, etc. The most classic is the drip oil cup. The drip oil varies significantly with the viscosity of lubricating oil, bearing clearance and oil supply hole location.
Ring lubrication
Depend on the shaft and can rotate the ring in the oil pool of lubricants to bearing (only can be used for horizontal spindle lubrication method), is applicable to medium speed and high speed bearing diameter of axle is greater than 50 mm, oil ring had better be seamless, bearing width to diameter ratio less than 2, can use only one oil ring, otherwise need two oil ring.
Wick lubrication
Depending on the capillary and siphon action of the oil rope, the lubricating oil in the oil cup is led to the bearing, mainly used for light and medium load bearing with peripheral speed less than 4 ~ 5m/s, in addition, the oil rope can play a filtering role in the whole process.
Lubrication oil pad
Using the capillarity of the oil pad, the lubricating oil in the oil pool is applied to the surface of the axle diameter.The oil supply for pad lubrication is usually only 1/20 of that for oil lubrication.
Oil bath lubrication
This method of lubrication is to dip part of the bearing into the oil, which is usually used for the thrust bearing of the vertical shaft, but not for the radial bearing of the horizontal shaft.
Splash lubrication
Oil supplied to the bearing by the slapping of the rotating parts in the tank, suitable for higher speed bearings.
Spray lubrication
The method of spraying the lubricating oil on the friction surface after atomizing is suitable for high speed bearings.
Pressure feed lubrication
Oil is supplied to the bearing by the pressure of the lubrication pump, and the lubricating oil from the bearing is recovered to the oil pool for recycling.
Circulating oil lubrication
The filtered oil is transferred to the bearing parts by oil pump, and the lubricating oil after the bearing is filtered and cooled down for use.Because circulating oil can take away a certain amount of heat, make the bearing cooling, so the method is applicable to the higher speed of the bearing components.
Spray lubrication
The high pressure oil is shot into the bearing by the oil pump through the nozzle, and the oil shot into the bearing flows into the oil groove through the other end of the bearing.
When the bearing rotates at a high speed, the roller and the retainer also rotate at a relatively high speed to make the surrounding air flow. It is difficult to send the lubricating oil to the bearing with the general lubrication method.
Bearing lubrication is a continuous work, the oil replacement cycle based on the use of the bearing and the amount of oil.
Under normal circumstances, when the operating temperature is less than 50℃, dust less good environment use, replace once a year, when the oil temperature reaches 100℃, to replace once a month or less.
Six principles of lubrication selection
After the above analysis, the advantages and disadvantages of various lubrication methods have been comprehensively evaluated, so in terms of the choice of bearing lubrication mode, the appropriate way can be selected according to the actual operating conditions. The main principles can be summarized as follows:
1) if the running speed and temperature rise indexes of the bearing are reasonable, the way of grease can be selected in preference.
2) among all lubricating oil lubrication modes, the one with a higher comprehensive index in technical and economic aspects is drip lubrication, so attention should be paid to the selection process.For drip lubrication, if the automation system can be used to control the drip lubrication better, then this way will have a good future.
3) if it is a heavy-duty bearing with low speed or a hollow bearing with high speed, the lubrication method of pressure cycle can be selected.
4) high speed light load bearing can choose dispersion droplets or oil mist lubrication;High speed heavy duty should choose jet lubrication.
5) the comprehensive technical and economic indicators of splash lubrication and oil bath lubrication are relatively low, and should be used as little as possible or not.
6) if the bearing is a complete set of equipment, in the process of choosing the lubrication mode, the lubrication mode and characteristics of other components should be fully considered, and the lubricant of the same type or variety should be used as far as possible, so that a lot of operating costs can be reduced in the operation.
When is it more appropriate to replace bearing grease?
As you probably know, grease plays a very important role in the use of bearings.Then someone will ask, is it possible to use grease indefinitely to lubricate the bearing?When and how much oil should you change?In fact, these problems are complex problems of bearing maintenance technology.
To the question whether grease can be used indefinitely, the affirmative answer is no.Because excessive use of grease, is a lot of damage to the bearing.
The grease has a good effect on the bearing, its adhesion, wear resistance, temperature resistance, rust resistance and lubricity are good, can improve the high temperature oxidation resistance, delay the aging, can dissolve the accumulation of carbon, prevent metal dust and grease coalescence, improve the mechanical wear resistance, pressure and corrosion resistance.
However, the more grease filling, the greater the friction torque.For the same amount of filling, the friction torque of sealed bearings is greater than that of open bearings.After the filling amount of grease is equal to 60% of the internal space volume of the bearing, the friction torque no longer increases significantly.This is because most of the grease in the open bearing has been extruded and the grease in the sealed bearing has been lost.
With the increase of the filling amount of grease, the temperature rise of the bearing increases linearly. With the same filling amount, the temperature rise of the sealed bearing is higher than that of the open bearing.It is generally believed that the grease filling amount of sealed rolling bearings shall not exceed about 50% of the internal space at most.
Generally speaking, the lubrication plan of the bearing is determined according to the time.Equipment suppliers usually make lubrication plans based on operating time.In addition, equipment suppliers often provide guidance on the amount of lubricating oil during their maintenance planning process.For the staff, short-term change of lubricating oil is very common, and often add more grease.
