NSK Turntable bearing, also known as slewing bearing, is a large bearing that can bear large axial load, radial load and overturning moment at the same time. NSK turntable bearings are generally equipped with mounting holes, internal or external gears, lubricating oil holes and sealing devices, which can make the design of the mainframe compact, reliable, and easy to maintain.
Rotary table bearings include toothless, externally toothed and internally toothed four-point contact ball bearings, double-row angular contact ball bearings, crossed cylindrical roller bearings, crossed tapered roller bearings and three-row cylindrical roller combined bearings. Kinds of structure. Among them, four-point contact ball bearings have a higher static load capacity; cross cylindrical roller bearings have a higher dynamic load capacity; cross tapered roller bearings can make the bearings have greater support rigidity and higher rotation through pre-interference Precision.
Turntable bearings are widely used in large-scale slewing devices such as crane machinery, mining machinery, construction machinery, port machinery, marine machinery, high-precision radar machinery and missile launchers.
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1. Wind turbine
The yaw bearing is installed at the connection between the tower and the cockpit, and the pitch bearing is installed at the connection between the root of each blade and the hub. Each wind turbine uses one set of yaw bearings and three sets of pitch bearings. The material of the yaw and pitch bearing ring is 42CrMo, the heat treatment adopts overall tempering treatment, and the raceway surface is quenched. The bearing conditions of yaw and pitch bearings are complicated, and the impact and vibration are relatively large. Therefore, the bearings are required to withstand both impact and large loads. The service life of the wind turbine generator requires 20 years, and the cost of bearing installation is relatively large. Therefore, the life of the yaw and pitch bearing must also reach 20 years. The hardness of the bearing ring base is 240-280HB, which can withstand the impact without plastic deformation. At the same time, the hardness of the raceway surface quenching reaches 55-62HRC, which can increase the contact fatigue life and ensure the long life of the bearing.
2. Marine crane
Marine cranes generally use double-row reducer balls, four-point contact balls, and three-row roller internal gear structure turntable bearings. Depending on the load carrying capacity, three-row roller turntable bearings are usually used in heavy-duty cranes, four-point contact ball turntables and Double-row reducer ball turntable bearings are used for light cranes. Since the crane works in the environment of -20°C—+45°C, the mechanical properties of the materials of such bearings are relatively high.
3. Offshore platform crane
According to different load-bearing capacity requirements, offshore platform cranes usually use four-point contact ball turntables and three-row roller internal gear turntable bearings. The slewing bearing used in offshore platform cranes has special material requirements. The mechanical properties of the materials must ensure the safety factor under extreme load. The Charpy impact test for forging sampling can reach an average value of 42J@-20°C or 27J@-40. °C. The finished bearing is subject to classification society certification.
4. Port mobile crane
Port cranes usually use three-row roller turntable bearings with internal or external teeth of 4 meters in diameter to withstand high tipping moments.
5. Stacker reclaimer
The turntable bearings used in stacker and reclaimer usually adopt ball and column joint type, three-row roller type and cross roller type, most of which are more than 3 meters in diameter. Due to the harsh working environment and heavy dust, this type of bearing has the characteristics of high load capacity, long life and good sealing performance.
6. Ferris wheel
Used for four-point contact ball turntable bearings on the ferris wheel, the outer diameter is 4100mm larger and the thickness is 85mm
7. Ship unloader
The turntable bearings used in ship unloaders usually adopt a three-row roller structure with external teeth and a diameter of about 4 meters.
8. Tower crane
The turntable bearings for tower cranes are usually small-size four-point contact ball turntable bearings or double-row ball turntables, with a diameter not exceeding 2 meters.
9. Radar antenna
Short-wave antennas generally use three-row roller-structured turntable bearings, which rotate slowly.
10. Shield machine
The diameter of the turntable bearings for shield machines ranges from 2.5 meters to 6 meters, and some have larger diameters. These types of bearings work under very harsh conditions. The bearings carry large loads, have strong corrosion resistance, and have a short life.
11. Ladle turntable
Turntable bearings for ladle turntables usually use a three-row roller structure. Because they work under harsh conditions with dust and high temperatures, they have high requirements for retainers, grease, and sealing strips.
12. Construction Machinery
Turntable bearings for construction machinery usually use small-size four-point contact ball turntable bearings with a diameter not exceeding 2 meters.
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