Common structural forms of slewing ring bearings

The slewing bearing is mainly composed of inner and outer rings or upper and lower rings, rolling bodies, seals, etc., among which the main upper and lower rings of the bearing are forged from alloy steel. Because of the different shape of the rolling body and the installation form, the bearing is divided into:

• Cross roller bearing;
• Single-row four-point contact ball slewing support;
• Double volleyball slewing support;
• Three row roller slewing support;
• Single row roller single volleyball rotary bearing.

The upper and lower rings of the bearing body are usually made of 42CrMo. After forging, they are machined and then tempered, and the racetrack surface is quenched. The quenching hardness of raceway surface is about HB256 ~ 279 and HRC 55 ~ 60 after quenching. The surface of raceway shall be ground after quenching, so that the surface roughness of the raceway shall not be less than 1.6 m. The main upper and lower rings of the bearing should be inspected in the forging and processing process to ensure that there are no defects such as shrinkage, sand holes, pores and cracks beyond the permitted scope. The commonly used slewing bearing of the rotary device of the bucket wheel stacker and recharger mainly includes the forms of cross roller, three row roller and single row roller volleyball, among which the highest price is three row roller.

The single-row cross roller type structure is that the bearing roller is a single-row roller structure. The axes of all rollers form an Angle of 45° with the horizontal plane. The rollers are respectively installed in the 90° V-shaped groove between the inner ring and outer ring of the bearing. Single row cross roller slewing support is characterized by compact structure, light weight, small assembly clearance, high positioning accuracy and low cost. Single row cross roller slewing support can bear axial force, tilting moment and larger radial force at the same time, it is widely used in medical equipment, lifting transportation, construction machinery and other products. Single row cross roller slewing support is not suitable for heavy duty and frequent working machinery equipment. At present, in order to reduce the cost, many manufacturers choose this kind of bearing as the rotary bearing of the stacker.

The single row roller single volleyball slewing bearing is two kinds of supporting parts which bear radial load and axial load respectively, namely, the roller bears axial load and the ball bears radial load. Some European manufacturers, after considering the cost factor, choose this kind of bearing as the rotary bearing of stacker.

Taking the bucket turbine as an example, the three-row roller slewing bearing is the most ideal slewing bearing for the bucket wheel stowage and reclaiming machine. Its characteristic is that its ability to bear axial load, radial load and overturning moment is larger than other bearings of the same size, and it has a relatively high service life in the bearings of the same size.