Do you know the following expertise in wind power bearings?
In recent years, wind power in emerging markets around the world has developed rapidly. Against the backdrop of national policy support and tight energy supply, China's wind power equipment manufacturing industry has risen rapidly, and the market demand for wind power equipment has grown rapidly, which has also driven the development of wind turbine bearing.
(Freely contact with Mr Gavin Chu(firstname.lastname@example.org) if any wind power bearings demand or other industrial bearings have requirement)
Bearings are the core components of wind turbines. Wind power bearings range from blade bearing, shafts bearing, yaw bearing to high-speed bearings used in gearboxes and generators. Let ’s takes a look at wind power bearings together!
Each set wind power equipment require 1 set of yaw bearing (slewing bearing) and 3 sets of pitch bearing (slewing bearing) for each wind turbine equipment 3 sets of machine bearings (deep groove ball bearings, cylindrical roller bearings), 2 sets of main shaft bearings (spherical roller bearings), a total of 9 sets.
In addition, there are gearbox bearings, and gearboxes have three structural forms. The first form requires 15 sets of bearings, the second form requires 18 sets of bearings, and the third form requires 23 sets of bearings. In this way, the average number of wind turbine bearings is 27 sets.
The structural forms of bearings for wind turbine generators mainly include four-point contact ball bearings, cross roller bearings, cylindrical roller bearings, spherical roller bearings, deep groove ball bearings, and so on. The yaw bearing is installed at the connection between the tower and the cockpit, and the pitch bearing is installed at the connection between the root of each blade and the hub.
Features of wind power bearings
1、使用环境恶劣；Harsh working environment
2、高维修成本； High maintenance cost
3、要求高寿命； Require long usage life
Classification of wind power bearing
The bearings for wind generators mainly include: yaw bearings, pitch bearings, spindle bearings, generator bearings，transmission system bearing (spindle and gearbox bearing)
Bearing type: deep groove ball bearings, angular contact bearings, etc.
Working condition characteristics: high speed (1000-1500rpm), high temperature (90-120 ° C) and heavy load.
Requirements for grease: excellent shear stability, good oxidative stability, good anti-wear performance, excellent low-temperature starting performance, etc.
2.2主轴轴承 spindle bearing
Bearing type: tapered roller bearing, spherical roller bearing, etc.
Characteristics of working conditions: low speed (<25rpm), wide temperature range, heavy load and large change, vibration, high humidity.
Requirements for grease: excellent anti-wear performance, good oxidative stability, excellent low-temperature starting performance, good water resistance, etc.
2.3 变桨/偏航轴承(pitch/yaw bearing)
Bearing type: Four-point contact ball bearings, etc.
Characteristics of working conditions: stop more than rotation, wide temperature range, heavy load, vibration, high humidity.
Requirements for grease: excellent anti-corrosion and anti-fretting wear performance, excellent low-temperature startup performance, good water resistance, good oxidation stability, etc.
Production process requirements for wind power bearings
It is necessary to control the forging temperature and avoid large grains;
It is necessary to control the modulation process and ensure the tempering organization of the heart, thereby ensuring its mechanical properties;
Control of the depth of the surface IF hardened layer;
Avoid fine cracks on the surface.
Lubrication analysis of wind power bearings
The speed of the input shaft of the wind power gearbox is generally 10-20 rpm. Due to the relatively low speed, it is difficult to form an oil film on the input shaft bearing (that is, the planet carrier support bearing).
The role of the oil film is to separate the two metal contact surfaces when the bearing is running to avoid direct metal-to-metal contact.
We can introduce a parameter λ to characterize the lubrication effect of the bearing.
(λ is defined as the ratio of the thickness of the oil film to the sum of the roughness of the two contact surfaces)
If λ> 1, it means that the thickness of the oil film is sufficient to separate the two metal surfaces, and the lubrication effect is good;
If λ <1, it means that the thickness of the oil film is not enough to completely separate the two metal surfaces, and the lubrication effect is not ideal.
Bearings may be damaged due to poor lubrication conditions. Because wind power gearboxes generally use circulating oil of ISOVG320 viscosity, if we find that λ is less than 1, we can only improve the lubrication effect by reducing the roughness of the bearing raceways and rollers.
In addition, in the design of the gearbox, the planetary support bearing should try to avoid that the size of the bearing at one end is too small. In actual application analysis, we found that even if the life meets the conditions, this design will cause the linear velocity of the small bearing too low to form the oil film.
Analysis of load bearing area of wind power bearings
Only a part of the running rollers bears the load, and the area where these rollers are located is called the bearing area of the bearing.
The magnitude of the load and the running clearance of the bearing will affect the bearing area. If the range of the load area is too small, the rollers are prone to slippage in actual operation.
For wind power gearboxes, if the design of the main shaft adopts a double bearing support scheme, then theoretically only torque is transmitted to the gearbox. In this case, after a simple force analysis, it is not difficult to find that the load on the planetary support bearing is relatively small, so the bearing area of the bearing is often relatively small, and the roller is prone to slip. In the design of the wind power gearbox, the planet carrier support bearing generally adopts the scheme of two single-row tapered bearings or two full-compliment cylindrical bearings.
We can increase the load zone by properly preloading tapered roller bearings or reducing the clearance of cylindrical roller bearings.
Technology of winder power bearing
Design and analysis: mainly depends on the empirical analog design at present, and the study of the force analysis and load spectrum is almost blank. The difficult technology is the failure-free operation of the main shaft bearing for more than 13 * 104h, and has a reliability of more than 95%; the high load capacity design of the gear box bearing with high damage rate.
Material: Different parts of the bearing are made of different materials and heat treatments, such as improving the low temperature (environment temperature -40 ℃ ∽-30 ℃, bearing working temperature around -20 ℃) impact performance of 40CrMo steel for yaw and pitch bearings. Heat treatment method, surface induction hardening depth of the hardened layer, surface hardness, soft band width and control of surface cracks; gearbox bearings equivalent to the development of foreign STF, HTF steel and control of the optimal content of residual austenite Research; In the case where there is still a certain gap in the quality of domestic vacuum degassed steel, the spindle bearing is manufactured by electroslag remelting and carburizing steel ZG20Cr2Ni4A, etc.