Imported bearings for wind turbines can be roughly divided into three categories: yaw bearings, rotor bearings, transmission system bearings (spindle and gearbox bearings).Yaw bearings are installed at the connecting part between the tower and the cockpit, and the rotor bearings are installed at the connecting part between the root of each blade and the hub.One set of yaw bearings and three sets of variable blade bearings are used for each wind turbine (some wind turbines below megawatt level have non-adjustable blades, but do not use variable blade bearings).
1 code method
Wind turbine yaw, variable propeller bearing code method adopts the JB/T 10471-2004 in rotary bearing code method, but the wind turbine yaw, variable propeller in the double row four-point contact ball bearing type wheel bearings, bearing and the structure of code in JB/T 10471-2004 had no rules, therefore, the increase in this standard the double row four-point contact ball bearings.Since the structural type code of single-row four-point contact ball disc bearing is denoted by 01, while the structural type code of 02 is denoted by the double-exclusion diameter ball disc bearing structure, it is stipulated that 03 represents the double-row four-point contact ball disc bearing structure
2. Technical requirements
This standard stipulates that the materials of yaw and variable propeller bearing rings should be 42CrMo. The heat treatment should adopt overall tempering treatment, and the hardness after tempering should be 229HB -- 269HB. The raceway part should adopt surface quenching, and the quenching hardness should be 55hrc-62hrc.Due to the wind turbine yaw, rotor bearing force situation is complex, and the bearing bearing impact and vibration is relatively large, therefore, the requirements of imported bearings can bear both impact, and can bear a larger load.The main engine life of wind turbine requires 20 years, and the cost of bearing installation is relatively large. Therefore, yaw and variable blade bearings are required to have a life of 20 years.In this way, the matrix hardness of bearing ring is 229hb-269hb, which can withstand impact without plastic deformation. Meanwhile, the surface hardening hardness of raceway part reaches 55hrc-62hrc, which can increase the contact fatigue life and guarantee the long service life of bearing.
2.2 low temperature impact work
This standard requires low-temperature impact work of yaw and rotor wheel bearing rings: -20 ℃Akv is no less than 27J, and the Akv value in cold state can be determined through consultation with the user.Wind turbines may work in extremely cold areas, the environment temperature as low as - 40 or so, the bearing of the working temperature is about 20 ~ C -, bearing under the condition of low temperature must be able to bear the impact load of big, therefore, request of bearing ring material after the tempering process must be low temperature impact test, take the part of the bearing ring to make sample or is the same as the ring the same performance and heat treatment under the condition of sample, in - 20 ~ C environment impact test.
2.3 bearing ring
Because the transmission accuracy of the wind turbine bearing is not high, and the tooth ring diameter is relatively large, the gear modulus is relatively large, therefore, the general requirements of the accuracy of the gear grade according to GB/T10095.2 --2001 in grade 9 or 10.However, due to the impact between the pinion gear and the bearing ring under the working condition, the tooth surface of the bearing ring should be quenched. The hardness of the pinion ring is generally 60HRC. Considering the design of equal service life, the quenched hardness of the tooth surface of the large gear should be no less than 45HRC.