Wind power bearings are special bearings that are used in harsh environments, require high maintenance costs, and require high life. Bearings for wind turbines mainly including: yaw bearing assemble, wind blade main shaft bearing, transmission bearing, generator bearing, etc. Bearing structure: cylindrical roller bearings, spherical roller bearings, deep groove ball bearings, etc. the technology of large yaw bearing assembly and wind blade main shaft bearing are relatively difficult, and now they basically rely on imports, which is one of the difficulties in the localization of wind turbines. The localization of fan bearings can improve the design and application level of the domestic bearing industry, narrow the gap with foreign advanced levels, and promote the development and technological progress of the domestic bearing industry. On the other hand, it can reduce the cost of wind power and accelerate the development of new energy and renewable energy in my country.

The wind power bearing is an important part connecting the steering of the yaw, pitch and transmission systems in the unit, corresponding to the yaw bearing, pitch bearing and main shaft bearing (mentioned in the processing technology question). Its main function is to support the rotating shaft or other moving bodies, guide the rotating or moving motion and bear the load transmitted by the shaft and the parts on the shaft. Its accuracy, performance, life and reliability play an important role in the performance and reliability of the main engine

Maybe everyone has seen the working environment of wind turbines, open field work, harsh working conditions, great changes in temperature, humidity and bearing load, wind speed up to 23m/s, and impact load, it is this harsh .Therefore, there are high requirements for the sealing performance, lubrication performance, impact resistance, life and reliability of the bearing. The generator will start when the wind is 2~3 and can track the change of the wind direction, so the bearing structure needs to be specially designed. Designed to ensure low friction and high sensitivity, large yaw bearings require teeth on the outer ring. In order to better achieve the best state of the fan, the bearing design, material, manufacturing, lubrication and sealing must be specially designed to provide a stronger guarantee for the good operation of the wind power equipment, which can greatly improve the performance and reliability.

Maintenance is equally important in wind power plant systems. Wind turbines are often located in difficult to maintain places, they are often installed in the mountains, in the desert or on the coastline. Condition monitoring systems can help monitor the performance of drive trains, while predictive maintenance can improve the performance and reliability of these systems and increase equipment uptime. For example, monitoring equipment status through vibration analysis, oil analysis and infrared thermal imaging to determine the maintenance process of the best maintenance time; through predictive maintenance methods, the operation reliability of equipment can be improved, and only when the equipment needs maintenance maintenance, reduce over-maintenance, and reduce maintenance costs.

1. Processing technology of fan bearings

1.1 Pitch bearing:

Inner ring—rough turning → quenching and tempering → semi-finishing turning → soft groove grinding → groove quenching → finishing turning, rough grinding → hole processing, gear processing → gear quenching → final grinding, fine grinding;

Outer ring—rough turning → quenching and tempering → semi-finishing turning → soft groove grinding → groove quenching → finishing turning, rough grinding → hole processing → final grinding, fine grinding.

1.2 Yaw bearing:

Inner ring—rough turning → quenching and tempering → semi-finishing turning → soft groove grinding → groove quenching → finishing turning, rough grinding → hole processing → final grinding, fine grinding;

Outer ring—rough turning → quenching and tempering → semi-finishing turning → soft groove grinding → groove quenching → finishing turning, rough grinding → hole processing, gear processing → gear quenching → final grinding, fine grinding.

2.Fan bearing technology

2.1Yaw bearing assembly

 The yaw bearing assembly is the guarantee for the wind turbine to track the change of wind direction in time. When the fan starts to deflect, the yaw acceleration E will generate an impact moment M=IE (I is the cabin inertia). The higher the yaw speed d, the greater the resulting acceleration 6 . Since I is very large, this multiplies the already large impact force. In addition, if the fan deflects during operation, the yaw gear will bear a considerable gyro moment, which will easily cause fatigue failure of the yaw bearing.

According to the force characteristics of fan bearings, the yaw bearing adopts a "zero clearance" designed four-point contact ball bearing, and the groove is specially designed and processed to withstand large axial loads and moment loads. The yaw gear should choose the appropriate material, modulus, tooth surface profile and hardness to ensure the matching of the life of the driving gear. At the same time, it is necessary to take targeted heat treatment measures to improve the strength of the tooth surface, so that the bearing has good wear resistance and impact resistance.

The fan is exposed in the wild, so there are strict requirements on the sealing performance of the bearing. The sealing type of the bearing must be optimized and the sealing performance of the bearing should be simulated to study to ensure that the life of the bearing is the same as that of the fan. The fan is installed at a height of 40m, and the assembly and disassembly costs are expensive, so it must have very high reliability, and generally requires a life span of 20 years. In addition, the bearing structure is complex, so a computer simulation test must be carried out before the installation test to ensure the bearing design. The parameters are correct.

2.2 Fan blade main shaft bearing

The blade main shaft is supported by two spherical roller bearings. Since the main shaft of the fan blade bears a very large load, and the shaft is very long and easily deformed, it is required that the bearing must have good self-aligning performance. Determine the internal structural parameters of the bearing and the structural form of the cage so that the bearing has good performance and long life.

2.3 Transmission bearings

There are many types of bearings in the transmission, mainly lubricated by the gear oil in the transmission. There are many metal particles in the lubricating oil, which greatly shortens the life of the bearing. Therefore, a special heat treatment process is required to make the surface of the raceway compressive stress, reduce the sensitivity of the raceway to particle impurities, and improve the life of the bearing. At the same time, according to the working conditions of the bearing, re-optimize the design of the bearing structure, improve the bearing processing method, and further improve the performance index of the bearing.

2.4 Generator bearings

The generator bearings adopt cylindrical roller bearings and deep groove ball bearings. Through the structural design of these two bearings, the improvement of processing technology, the control of cleanliness in the production process and the optimization of related components, the noise of bearing vibration is reduced, so that the bearing has good low-noise performance.

3. Materials of wind power bearings

Bearings in different parts use different materials and heat treatment, such as improving the impact energy and other mechanical properties of 40CrMo steel for yaw and pitch bearings at low temperature (environment temperature -40°C∽-30°C, bearing operating temperature at about -20°C) Heat treatment method, control of hardened layer depth, surface hardness, soft band width and surface cracks of surface induction hardening; research on the development and control of the optimal content of retained austenite for speed increaser bearings equivalent to foreign STF and HTF steels ; The main shaft bearing is made of electroslag remelted carburizing steel G20Cr2Ni4A when there is still a certain gap in the quality of domestic vacuum degassed steel.

4. Hard turning part , related materials and cutting tools selection

Slewing ring bearings and wind power bearings are large-scale bearings, with a diameter of more than 1 meter or even nearly 3 meters. After heat treatment, there are more or less deformation problems. In addition, their own hardness is above HRC55, which is difficult for hard turning tools. --CBN inserts bring great challenges.

The hard turning parts of wind power bearings and slewing ring bearings are mainly the outer raceway, inner raceway and rib position. The common material is CBN inserts BN-H200 developed by Halnn. Blade-based, RCMX series, RCGW series, RNGN series, RCGO series, single-sided overall composite CBN insert, circular single-sided composite perforated CBN inserts, and overall polycrystalline PCBN cutters can be customized. Not only the cutting allowance is large, but also can Withstand interrupted cutting, which can effectively meet the needs of manufacturers to reduce costs and increase efficiency.

5. What are the advantages of Halnn CBN inserts BN-H200

CBN inserts BN-H200 is mainly used in the fields of large slewing ring bearings and wind power bearings, and the current market share has reached more than 60%. CBN inserts BN-H200 material has both excellent wear resistance and impact resistance toughness. It can cut with a large margin during rough machining, and the tool will not collapse under intermittent conditions. It can obtain roughness and dimensional accuracy within Ra1.6 during finishing machining, and can be dry cut. It can also be used in wet cutting, air cooling and other methods, and the cutting performance is extremely stable, which can replace imported cutting tools and homogeneous PCBN cutting tools.