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High speed bearings have higher accuracy and less surface roughness than vulgar bearings. The intuitive Difference difference is that the surface of high-speed bearing is smoother than that of vulgar bearing. If the outer ring and inner ring are shaken, the clearance of high-speed bearing is smaller.
The general high-speed bearing refers to the bearing with a speed of 60 Difference meters per second. The high speed, medium speed and low speed of the bearing are not determined by the speed, but by the linear speed. A small bearing can rotate tens of thousands of times, which is not a high-speed bearing.
A large bearing can rotate hundreds of times, which is a high-speed bearing. In the sliding bearing, hydrostatic bearing, hydrodynamic bearing, Difference aerostatic bearing and aerodynamic bearing are all suitable for high-speed rotation.
High speed bearing and ordinary Difference bearing: installation, coordination and adjustment of high speed bearing
1. Fit and clearance of high-speed bearing since high-speed bearing shall meet the requirements of both high-precision bearing and high- Difference temperature bearing, the following two points shall be considered when considering its fit and clearance:
(1) Size change and hardness change from normal temperature to high Difference temperature;
(2) The change of force system and shape caused by centrifugal force at high speed.
In short, under the conditions of high speed and high temperature, it is difficult to maintain the accuracy and working performance of the bearing from the selection of fit and clearance.
In order to ensure that the raceway deformation after bearing installation is small, the interference of Difference interference fit cannot be too large, and the centrifugal force at high speed and thermal expansion at high temperature can offset the normal pressure on the mating surface.
Or relax the mating surface, so the interference must be calculated carefully on the premise of considering the above two factors. The effective interference at room temperature and constant speed may be invalid for high-speed bearings.
If the contradiction between the calculation results is too large (usually only at ultra-high speed), only the dual lubrication measures of under ring Difference lubrication method and hydrostatic lubrication method can be adopted, and this scheme may make the DMN value of the bearing break through the 3 million mark.
Thermal expansion at high temperature, or offset the normal pressure on the mating surface. Or relax the mating surface, so the interference must be calculated carefully on the premise of considering the above two factors. The effective interference at room temperature and constant speed may be invalid for high-speed bearings.
we should not only consider the above factors, but also consider the influence of the thermal elongation of the shaft on the clearance. It is required that the bearing has clearance under the working state, that is, under the working temperature,
and this clearance is formed under the condition of accurate alignment of the ball groove centers of the inner and outer rings. As high-speed bearings strive to reduce relative sliding and internal friction, do not use the method of relative dislocation of the inner and outer rings along the axial direction to adjust the clearance of ball bearings.
When considering the fit interference and clearance of the bearing, pay attention to the characteristics that the material becomes soft and easy to deform at high temperature, and the possibility of permanent deformation caused by multiple temperature changes from normal temperature to high temperature.
2. Requirements for relevant parts of main engine
The high-speed bearing requires the rotating system where the bearing is located to undergo precise dynamic balance, and the parts where the bearing is installed between the shaft and the seat hole shall have higher dimensional accuracy and shape and position accuracy than the general requirements,
especially the coaxiality and the perpendicularity of the shoulder to the seat hole or journal. When considering these problems, we must also pay attention to the high-speed factors and high-temperature factors during bearing operation.
In order to overcome this contradiction, measures such as reducing surface roughness and improving surface strengthening can be taken to improve the support stiffness, and hollow shafts can be used to reduce the system mass.