High-speed bearing lubrication difficulties lubricant is easy to spread out, and the rolling surface are difficult to stick, or by high-speed airflow around the bearing block and could not enter the bearing, and enter the bearing lubricant speed is too high, sometimes can make the bearing damage, such as cage appeared pitting, desquamation and aggravate the friction and wear.
High-speed bearing most of the working temperature at 200 ℃ or so, and tend to be higher, if not through strong cooling, the temperature will continue to rise and adverse to the strength and hardness of the bearing is bearing once losing their ability to keep accurate shape, will aggravate the friction and make the temperature rising rapidly, resulting in a loss of material strength and hardness and make further bearing failure quickly.
Due to the high speed bearing is sensitive to wear, and prone to wear debris, if not timely out of bearing, will also cause a vicious cycle, fast bearing failure.
Therefore, the task of high-speed bearing lubrication must effectively movement from the lubricant to the bearing surface, FAG 6321 bearings distributor http://www.fagbearings-hk.com/product/FAG-6321-bearings-1757.htmland heat away from the bearing, and bearing the abrasive dust or dirt removed.
Will now commonly used in high-speed bearing lubrication methods and effective lubricant are:
1. Spray lubrication
Spray lubrication oil from close to the bearing nozzle holes, at a rate of 10-20 m/s into bearing, is usually sprayed into the cage and inner ring or outer ring gap, which is formed by the bearing lubrication and cooling method.
To the inner diameter of 30-35 mm small ball bearings, spray lubrication can achieve DMN limit value of 3 million for larger bearings is 2.5 million.
Double holes or porous nozzle can increase oil already, also can improve the efficiency of the use of lubricating oil, and the nozzle or the two ends are a nozzle, and can improve the effect of lubrication and cooling, but when the DMN value is close to 2 million, because of the influence of the centrifugal inertia and wind resistance, into the bearing oil is only 70% or less of nozzle flow.
2. Under the ring lubrication
Ring under the lubrication method is to use the centrifugal inertia, directly to the oil via ring opening, many radial hole and into the raceway surface, part of the oil along the inner ring below for axial flow and achieve the purpose of cooling the inner ring. Divided into two channels into the groove of the oil to drain out, by the way, will wear debris is falling from the cage and other parts to wash away.
This method of lubrication oil quantity much less than the oil lubrication, due to the dynamic mixing of oil lead to less power loss, the fever of bearing is also be improved, and even less likely than outer ring and inner ring temperature reducing bearing failure.
The lubrication method can also be used to cooling outer ring. When the outer ring are such lubrication bearings allow DMN value can be further improved.
Now this ring lubrication is widely used in all kinds of high-speed operation. Can achieve maximum DMN for large diameter from 120 ~ 200 mm ball bearing of 3 million; Of inner diameter 120 mm to 2.4 million tapered roller bearing, and combination of short cylindrical roller bearing inner ring for 3 million
3. Double lubrication
This approach is essentially the roller bearing inner ring of the hole and shaft neck hydrostatic oil film bearing, greatly reduced the speed of rolling bearing, so as to achieve the aim of reducing centrifugal force function, double lubricated bearing can significantly reduce the speed of the roller bearing inner ring, and thus allows for a higher degree of spindle speed, of bearing DMN value can be further improved.
4. The lubrication oil and gas
Biggest advantage is without having to change the lubrication oil and gas bearing structure under the condition that only by reducing friction bearing can achieve DMN values in 800000 ~ 1.5 million high-speed, for internal sliding bearing, the advantage of this approach is more significant.
(1) the principle and characteristics of the oil and gas lubrication oil lubrication principle is to use quantitative piston distributor will be very tiny amounts of oil (such as 0.01 m1), with the best cycle intermittently discharge, discharge of oil before reaching the bearing form continuous flow along with the air into the bearing.
The characteristics of oil and gas lubrication is as follows:
1) can be extremely trace quantitative oil supply continuous steady bearing, so can control the necessary minimum like grease oil. Due to different bearing types, but also takes different amount of lubricating oil, the quantitative piston pipe to each bearing, so can adjust the bearing oil.
The lubrication method of friction loss is about one over ten of the splash lubrication, the kinetic friction loss and temperature rise is also smaller than grease lubrication.
2) due to the lubricating oil and gas is less than the number of spray lubrication oil, and lubricating oil with appropriate oil droplets into the bearing, and therefore less pollution atmosphere. Such as oil and gas lubrication of the main shaft in propylene in about 2 h after continuous operation, measuring the degree of air pollution in the cabinet is only 0.03 mg/m3.
3) foreign dust or cutting fluid into the main shaft, which is due to the large number of air along with the trace oil supply (each bearing 20 to 30 l/min), make the main shaft inner pressure increase.
(2) the viscosity of oil and gas lubricating oil and lubricating oil and gas should be the necessary minimum supply of oil bearing, so it is very important to the choice of oil.
More angular contact ball bearing slide less than the sliding cylindrical roller bearing oil amount to more. Oil general standards have formula can be reference.
But the lower the viscosity of oil, or speed is higher, the required oil increased accordingly. In fact, the oil should be used according to the bearing load and speed conditions to decide.
In terms of the influence of the bearing temperature rise by lubricating oil viscosity, oil and gas lubricating oil supply is much less than the cycle. But in the oil under the same conditions, high viscosity, temperature rise slightly increased. Usually the oil-gas lubrication in 40 ℃, use for 10-3 cmrn2 / s oil viscosity.
Gas lubrication is a new research success has many characteristics of lubrication method, sliding more bearing in angular contact aunts bearing used in, for example, the DMN value can reach about 1.5 million.
5. High speed bearing lubricant
High-speed bearing lubricant should be considered according to the high temperature bearing lubricant, choose - that is, under the high temperature also have good performance of synthetic oil, or to the synthetic oil as base oil of grease. A second ester of MIL - L - 7808 and MIL - L - 23699 oil, oil mainly applied in the jet engine bearings.