Wind turbine bearings are generally divided into three types, including pitch bearing, yaw bearing, main shaft of transmission system and gearbox bearing. Generally, wind turbine generators need one set of yaw bearing and three sets of pitch bearing; The yaw bearing is installed at the connection between the tower and the cockpit, and the pitch bearing is installed and used at the connection between the blade root and the hub
1. Materials
42CrMo is required to be selected as the material of the yaw pitch bearing ring, and it needs to be quenched and tempered by the heat treatment method of overall quenching and tempering treatment; To make its hardness reach 229HB-269HB, the raceway of yaw pitch bearing needs to be quenched to make its hardness reach 55HRC-62HRC. Due to the complex stress situation and the relatively large impact and vibration, the wind power yaw pitch bearing is required to be able to bear large impact and large load at the same time. The installation cost of the main bearing of the wind turbine is large, so the service life of the yaw pitch bearing is required to be the same as that of the main engine, which can reach 20 years,
2. Low temperature impact energy
The collar of the yaw pitch turntable bearing is required to be able to withstand the low temperature impact of - 20 ℃ Akv and not less than 27J: to ensure that the wind turbine generator can work under the extreme cold ambient temperature of - 40 ℃ and can withstand the large impact under the low temperature condition of - 20~C. Therefore, the low-temperature impact energy test must be carried out after the collar material is quenched and tempered
3 Bearing ring gear
The drive accuracy of the wind turbine bearing is usually not high. The diameter of the gear ring and the gear modulus are relatively large. The impact of the pinion and the bearing gear ring is the main problem under the working condition. Therefore, the bearing tooth surface shall be quenched to make its hardness reach 60HRC and not lower than 45HRC
4 Clearance
The impact load borne by the pitch bearing in the working process is large, and the wind causes large vibration on the blade. Therefore, its clearance should be zero or with a certain negative clearance value, which can effectively reduce the fretting wear of the bearing under the working environment of large vibration. The yaw bearing requires a small clearance value of 0-501~m. In addition, when the bearing has a negative clearance or small clearance, the drive function of the drive motor needs to be guaranteed
5 Anti-corrosion treatment
The yaw pitch bearing of the wind turbine generator may need to be exposed to the air for work, which is prone to corrosion by pollution, high humidity and other factors. Therefore, the surface of the outer part requires anti-corrosion treatment, usually galvanizing.