The yaw bearing is installed at the joint between the tower frame and the cockpit, and the variable propeller bearing is installed at the root of each blade and the hub.Each wind turbine is equipped with one set of yaw bearings and three sets of variable rotor bearings (some wind turbines below the megawatt class are non-adjustable blades and do not need variable rotor bearings).
1. Identification code
Wind turbine yaw, variable propeller bearing code method is adopted in the JB/T10471-2004 slewing bearing code method, but the wind turbine yaw, variable propeller in the double row four-point contact ball slewing ring, and the code of the structure bearing no provisions in JB/T10471-2004, as a result, the increase in this standard the double row four-point contact ball bearings.Due to the structure of single row four-point contact ball slewing bearings with 01 type, according to the structure of code 02 said is double row reducer ball wheel bearing structure, thus provides 03 said double row four-point contact ball slewing bearing structure.
2. Technical requirements
2.1 material
According to this standard, 42CrMo is used as the material for the bearing sleeve of yaw and variable propeller bearing.In heat treatment, the hardness after tempering is 229HB~269HB.The raceway part adopts surface quenching, the quenching hardness is 55HRC-62HRC.Because of the complex force situation of the bearing of the variable rotor bearing of the wind turbine, the bearing is subjected to large impact and vibration, Therefore, it is required that the bearing can withstand both impact and large load.
The life of the main engine of the wind turbine requires 20 years, and the cost of bearing installation is large. Therefore, the life of yaw and variable propeller bearings is also required to reach 20 years.This bearing ring hardness is 229HB~269HB, able to withstand the impact without plastic deformation, and part of raceway surface quenching hardness reaches 55HRC~62HRC, can increase the contact fatigue life, so as to ensure the use requirement of bearing long life.
2.2 low temperature impact work
This standard for yaw and variable propeller bearings low-temperature impact energy requirements: - 20 ℃ Akv should not less than 27J, under the cold Akv value can be negotiated with the user.Wind turbines may work in extremely cold areas, the environment temperature as low as to 40 ℃ or so, bearing working temperature is about 20 ℃. 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 ℃ environment impact test.
2.3 Bearings gear ring
Because the drive precision of the bearing of wind generator is not high, and the diameter of the gear ring is large, and the number of gear modules is large, the precision grade of gear is generally required to be GB/T10095.Level 9 or level 10 in 2~2001.But due to the work condition between pinion and ring gear bearing impact, therefore, bearing ring gear tooth surface quenching, small gear tooth surface hardness is generally in the 60HRC, considering the life design, big gear tooth surface quenching hardness for not less than 45HRC.
2.4 Clearance
There are special requirements for yawing and variable propeller bearing in the aspect of clearance. Relative to the yaw bearing impact and variable propeller bearing load is large, the wind blows to the blade vibration is big, so the requirement is variable propeller bearing clearance should be zero clearance or slightly negative clearance value, so in the case of vibration can reduce the bearing of fretting wear. Yaw bearing is required to be small clearance 0-501~m.
In addition,because the wind turbine yaw and variable propeller bearing rotation are driven by the drive motor,bearing in negative clearance or small clearance should ensure that the drive motor can drive.Therefore, it is necessary to measure the starting friction moment at no-load after the bearing is assembled. The specific torque value varies according to the driving system of the main engine.
2.5 Anti-corrosion treatment
Wind turbine equipment work in the field, and yaw and variable propeller bearing is exposed outside, will be affected by air pollution and high humidity environment may also be corrosion bearing matrix, therefore, bare outside of yaw and change the blade bearing parts of the requirements for surface anti-corrosion treatment, generally USES galvanized processing.Paint the outside of the galvanized coating as required.
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