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F & F with the installation of high-speed bearings and the bearing clearance is necessary because high-speed precision bearings according to requirements, but also by high-temperature bearing requirements, taking into account their co-ordination and clearance, to take into account the following points:
(1) when the temperature rose to high temperature changes in the size and hardness changes;
(2) high speed centrifugal force caused by the force system changes and shape changes.
In short, high-speed, high temperature conditions, with and clearance from the choice should strive to maintain the accuracy and performance bearing, this is difficult.
In order to ensure that F & F after the installation of roller bearing deformation is small, the interference with the amount of interference can not be made too large, and high speed centrifugal force and high temperature thermal expansion, or offset with the surface normal pressure. Or so with the surface relaxation, the amount of interference must be considered under the premise of these two factors should be carefully calculated, at room temperature under constant speed and effective amount of interference for high-speed bearings may be invalid.
If the calculation results of this conflict is too large (usually only in the ultra-high speed only in this case), only to take part under the lubrication and hydrostatic lubrication and lubrication with a double measure, and this program has the potential to break the bearing dmn value 3 million mark.
In considering the high speed when the bearing clearance to consider not only the above factors, but also to consider the thermal elongation of the axis of F & F clearance, and called Bearing in working condition, that is the best operating temperature of clearance, while This clearance is included, the outer ring ball groove to precisely position the center of state formation. As high-speed bearings for lower internal friction and relative sliding, best not to use the inner and outer rings relative axial dislocation along the way to adjust the ball bearing clearance.
In considering the amount of interference with the bearings and clearance, to note that the material at high temperatures becomes soft and easily deformed features, and many times at room temperature to high temperature by the temperature change caused by the possibility of some permanent deformation.
F & F shaft bearing systems require both high rigidity and light requirements of quality as much as possible, in order to overcome this contradiction can be taken such as reducing surface roughness and improve the surface hardening measures to improve the supporting rigidity, the use of hollow shaft to reduce the system quality.
(1) of the problem
In the gas turbine and some machine tools and construction machinery, high speed and axial load, the use of ball bearings is life is too short, cylindrical roller bearings with axial load capacity is insufficient, the axial clearance is difficult to adjust, hoping to use tapered roller bearings break this problem.
(2) key technology that must be addressed
Increased imports of tapered roller bearings MSRHK speed limit to improve the technology lies in the inner wall with a large roller large end lubrication between the state, this area most likely to occur at high speed intense wear and burns, is the main reason to limit its high-speed .
(3) solution
General structure of the tapered roller bearings, the oil flow lines in the inner ring large rib and roller end contact area is difficult to get big oil, and this large relative sliding parts, and most just need lubrication.
(4) can be achieved
F & F high-speed bearing dmn value of up to 200 million, more than triple the normal structure, for example, such a gas turbine gearbox spindle bearings, the axial load 1000N conditions, to ensure 2L/min of oil on the No. 4 bearing a circular supply of turbine oil, the operating speed of up to 60,000 instead to avoid a burn.
