As a major bearing manufacturer in China bearing industry, Lily Bearing is well-known for developing all sorts of sophisticated slewing bearings, one type of which is a kind of slewing bearing called double-row Four-point Contact Ball Slewing Bearings. Recently, a team of engineers from Lily Bearing customized a kind of solution about double-row Four-point Contact Ball Slewing Bearings for a client's yaw pitch system.
The client is mainly engaged in the R&D of wind turbines. The wind turbines work outdoors all the time, which is a harsh working condition. It is obvious that the temperature and the humidity will directly affect the operation of the pitch bearings in wind turbines.
Further, when the wind reaches Level 2 or 3, wind turbines can get started and be able to rotate with the wind direction changing. Thus, slewing bearings with a high performance are required. Such kind of slewing bearings in the yaw pitch system should have an impact resistance, the reliability, the sensitivity, the good lubrication, the excellent sealing as well as a long life.
According to the client's working conditions, Lily's engineers used double-row Four-point Contact Ball Slewing Bearings with the model 16284001. They mounted these slewing bearings at the root of each blade and the connection part of the hub. They did this with the consideration of the equipment, the process characteristics as well as the testing methods. The purpose was to adjust the orientation of the turbine and the magnitude of the blade pitch angle, thus ensuring that the turbine can achieve vertical windward and that the output power is kept within a safe range.
The engineers also in advance evaluated the forces on the double-row Four-point Contact Ball Slewing Bearings in operation and analyzed the loads and the friction torques of the bearings during start-up.
According to the engineers, the double-row Four-point Contact Ball Slewing Bearings are designed with zero clearance, which can bear axial and radial loads as well as large overturning moments. When there are no loads or only pure radial loads, the four-point contact style appears between the steel balls and the inner and outer raceways. When there is an axial load or overturning moment, the balls are in two-point contact with the inner and outer raceways.
Lily's engineers also studied on the sealing performance of the double-row Four-point Contact Ball Slewing Bearings. The aim was to ensure that the parameters of the Four-point Contact Ball Slewing Bearings are accurate. Thus, the life of the double-row Four-point Contact Ball Slewing Bearings can be on par with the life of the wind turbine.
Double-row Four-point Contact Ball Slewing Bearings
In terms of the lubrication of double-row Four-point Contact Ball Slewing Bearings, the engineers adopted a special heat treatment process for some metal particles in the lubricant will affect the life of the slewing ring bearings. After overall tempering through the heat treatment, the hardness reaches 229HB-269HB. This can make the raceway surface produce a certain compressive stress, and further reduce the sensitivity of the raceway to metal impurities. It can also ensure the turntable bearings to withstand shocks without deformation, thus improve the bearing life.
Furthermore, the ring material of the double-row Four-point Contact Ball Slewing Bearings used in the pitch system was selected with the extreme temperature factor in mind. Some wind turbines may work in an extremely cold area where the ambient temperature may be -40℃ or the working temperature might be -20℃. For this, the engineers first tempered for the collar material of the Four-point Contact Ball Slewing Bearings, and then they used the way of simulating low temperature to do the impact power test.
What's more, the forces double-row Four-point Contact Ball Slewing Bearings used in the wind turbine pitch system might bear were complex. And these Four-point Contact Ball Slewing Bearings may be subject to the large shocks, heavy loads as well as the vibration. For this reason, the engineers used surface quenching technology for the raceway part, which has a quenching hardness of 55HRC-62HRC.
When the wind level is very high, the blade vibration in the pitch system will be frequent. Accordingly, the shock loads on the double-row Four-point Contact Ball Slewing Bearings will also be in a high position. In view of this, the engineers allowed the clearance of the double-row Four-point Contact Ball Slewing Bearings in the pitch system to be zero, or a smaller negative clearance value. This can reduce the bearing wear in vibration.
Further, after the double-row Four-point Contact Ball Slewing Bearings were assembled, the engineers measured the starting friction torque at no loads to reduce the errors in the bearing operation.
In addition to high-quality double-row Four-point Contact Ball Slewing Bearings that meet international standards, Lily Bearing can also provide clients with professional and top-torch services. The professional staff will help clients customize bearings and provide professional analysis according to their working conditions. In the communication with clients, they combined various technical parameters such as static and dynamic loads, inner and outer diameter tolerances and limiting speeds to provide clients with effective and feasible solutions.