Design and application of eccentric static pressure radial bearing 2018-09-27 17:55:05

Design and application of eccentric static pressure radial bearing
Compared with other types of bearings, hydrostatic bearings have the characteristics of wide speed range, high rotation precision, large bearing capacity, low friction coefficient, good vibration resistance and long service life. Practice has proved that the adoption of hydrostatic bearings has positive significance for the development of machinery manufacturing, aviation industry, metallurgical industry, precision measuring instruments and so on. In addition, compared with dynamic pressure bearings, hydrostatic bearings are easy to implement and easy to maintain and maintain. Therefore, for some factories with weak mechanical maintenance capabilities, it is of great practical significance to use them to retrofit precision machine tools that have reduced accuracy.
With the development of science and technology, people have put forward higher requirements for the performance of hydrostatic bearings. In recent years, many scientific literatures have introduced the research results in this respect. The eccentric static pressure radial bearing proposed in the literature 1 is one of them. Theoretical analysis and experimental verification show that the performance of eccentric static pressure radial bearing is better than that of ordinary radial bearing, which is suitable as the main shaft support of various machine tools.
1 eccentric static pressure radial bearing works

The hydrostatic radial bearing has a dynamic pressure effect after the journal is rotated. This dynamic pressure effect increases the bearing capacity and oil film stiffness of the hydrostatic bearing, but the general static pressure radial bearing is equally throttled. That is, the center of the bearing journal is coincident with the center of the bearing (referred to as concentric bearing), so in the case of small eccentricity, the dynamic pressure effect of the bearing is small, and it is almost completely supported by hydrostatic pressure. If the adjustable cavity is used to obtain equal throttling of each cavity of the bearing, that is, the center of the journal is offset from the center of the bearing in the direction to be loaded before loading, an eccentric bearing is obtained.

Therefore, when the shaft rotates at a certain speed, a strong dynamic pressure effect is generated, so that not only the pressure in the oil chamber of the asymmetrical oil wedge is increased, but also the pressure of the back carrier chamber is increased due to the rebound of the shaft center. This is advantageous for improving bearing performance. Theoretical analysis and experiments prove that the larger the initial eccentricity ε0, the greater the bearing capacity and oil film stiffness of the bearing.
2 eccentric static pressure radial bearing structure design

2 .1 oil cavity form of bearing
The traditionally used rectangular oil chamber can be used in the design of the bearing, or the "island oil chamber" can be used, but in order to further improve the performance of the bearing, the oil chamber of the bearing can be designed into a combined type. The oil chambers of I and IV in Figure 1 adopt the “peninsula oil chamber”. When the bearings are working, they should be guaranteed to be bearing chambers, which can generate large dynamic pressure effects and achieve the purpose of improving the bearing capacity of the bearings. The II oil chamber is located at the divergent gap, and the rectangular oil chamber structure can fully supplement the lubricating oil to avoid the back pressure zone. The III oil chamber is a back pressure chamber, and the “island oil chamber” is used to improve the oil film stiffness of the bearing.