Long Life Double Row Pitch Bearing for wind turbine

Long Life Double Row Pitch Bearing for wind turbine 

The service life of the main engine of the wind turbine generator is set at 20 years. Therefore, the reliability life of the wind turbine bearing (including pitch bearing, blade bearing, raw bearing) is required to be the same as the service life of the unit, and more than 20 years. This is because the bearing installation location is not easy to disassemble, and the disassembly cost is high, and the cycle is long.

The pitch bearing is installed at the connection between the root of each blade and the hub, and The yaw bearing is installed at the connection between the tower and the cabin, The pitch bearing and yaw bearing used for pitch and yaw system are oversized turntable bearings.

As the turntable bearing for wind turbine is not only subject to large overturning moment, but also affected by many complex fatigue loads such as aerodynamic force and blade rotation, and in addition to the requirements of high reliability and long life, it is more important to pay attention to the dynamic load capacity of the bearing, especially the anti-fatigue life of the raceway, when designing the structure.

Although the structural forms of pitch and rotary table bearings have been specified in domestic standards, there is no reasonable type selection structure. From the current installed use, the pitch bearings mostly use double-row four-point contact ball bearings, the yaw bearings mostly use single-row four-point contact ball bearings, and a few use cross rollers or other forms.

Material requirement for pitch bearing, blade bearing and yaw bearing:

The yaw bearing and pitch bearing rings of wind turbine bearings are generally made of 42CrMo steel. The heat treatment adopts the overall quenching and tempering treatment. The hardness after quenching and tempering is 229HB-269HB. The raceway part adopts surface quenching, and the quenching hardness is 55HRC-62HRC.

The bearing ring of transmission system is generally made of ZGGr15 or ZGGr15SiMn steel. Due to the complex stress conditions of the yaw and pitch bearings of the wind turbine generator, and the large impact and vibration that the bearing bears, the bearing is required to be able to withstand both impact and large load.

The base hardness of the bearing ring is 229HB-269HB to ensure that it can withstand impact without plastic deformation. At the same time, the surface hardening hardness of the raceway part should reach 55HRC-62HRC, so as to increase the contact fatigue life and ensure the service requirements for the long service life of the bearing.

Low temperature impact energy for pitch bearing, blade bearing and yaw bearing:

The wind turbine bearing standard requires that the low temperature impact energy of the bearing ring of the yaw bearing and pitch bearing : - 20 ℃ Akv, not less than 27J, and the Akv value in the cold state can be determined through consultation with the user.

Sometimes the working place of the wind turbine generator may be in a very cold area, where the ambient temperature is as low as - 40 ℃, and the normal working temperature is about - 20 ℃. This requires that the yaw bearing and pitch bearing can also bear large impact load under low temperature conditions. Therefore, after the bearing ring material is quenched and tempered, the low temperature impact energy test must be carried out.

That is, take a part of the bearing ring and make it into a sample, or select the sample with the same performance and the same heat treatment conditions as the ring, and conduct the impact energy test at the ambient temperature of - 20 ℃.