Time：2020.02.17 Source：Roller Bearings Suppliers
·Anti-corrosion treatment of an outer surface of variable propeller bearing and yaw bearing
For the anti-corrosion of a yaw bearing, we adopt the arc spraying long-acting anti-corrosion technology. Its technical characteristics are (1) long anti-corrosion life, up to more than 20 years:4 coating adhesion quotient along with the coating quality. The process line: semi-finished products preparation of inner and outer ring of bearing -→ pre-cleaning -→ pre-protection of the workpiece -→ sandblasting -→ temporary closure by arc spraying, as described below.
1) Development of semi-finished products of an inner and outer ring of bearing
In order to guarantee the appearance of the yaw bearing with high quality, arrange anticorrosive process after all machining, after the completion of the bearing parts in the assembly after the spray directly into the Treasury, guarantee will not be scratches on the coating.
The bearing semi-finished products that may have oil stains on the surface after mechanical processing. To ensure the spraying quality, cleaning procedures must be arranged before spraying.
3) Pre-protection of the workpiece
Before sandblasting and spraying, special surface pre-protection equipment is used to protect the workpiece's four-arc raceway, threaded hole, and non-sprayed surface.
The surface of the inner and outer ring of the bearing is roughened to increase the contact surface between the coating and the workpiece to make the surface of the workpiece more active and improve the bonding strength of the sheet.
5) Arc spraying
The equipment of arc spraying (pure aluminum or zinc) mainly includes dc power supply, spraying gun, air compressor, and air filter.
6) Closed treatment.
Due to the presence of holes in the sprayed coating; it is necessary to seal the layer to increase the corrosion resistance.
After spraying and assembling, the main surface of yaw bearing is gear surface, mounting thread surface, and arc raceway surface. The first two shall be coated with anti-rust oil after assembly, and the second shall be covered with lubricating oil during manufacture. The inner packaging of the finished product shall be closed and wrapped with plastic film, and the outer layer shall be covered with synthetic braid for protection, which can meet the requirements of anti-rust.
There are two sources of damping torque of yaw bearing after assembly: friction resistance of raceway part and friction resistance of sealing strip and sealing surface. The latter is a constant under the same processing conditions, so the damping torque of yaw bearing after assembly mainly depends on the former.
The frictional drag moment generated by the raceway during rotation primarily depends on the size of the bearing clearance. When the interspace is large, the resistance is small. When the interspace is low, the resistance increases correspondingly. Yaw bearings require zero interspace or negative clearance, the amount of which is determined by the friction damping torque after assembly. Therefore, the magnitude of friction damping torque after construction depends on the assembly clearance value of yaw bearing, and the formation of this value mainly depends on the precise size of the raceway before quenching. Raceway and the fire, the raceway after the fire pre-grinding size, and the size of the roller selected four links.
The force of wind power bearing (yaw bearing and variable propeller bearing) is complicated, and the impact and vibration of the bearing are relatively large. Therefore, it is required that the bearing can bear not only the effect but also take a large load. The life of the main engine of the wind generator is needed to be 20 years, and the cost of carrying installation is relatively high. Therefore, the experience of yaw and variable propeller bearing is required to reach 20 years.