1. Anti-corrosion treatment of the outer surface of pitch bearing and yaw bearing
For the anti-corrosion requirements of yaw bearings, we use the arc spray long-term anti-corrosion process. It uses special arc spraying equipment to melt, atomize and spray corrosion-resistant metal (pure aluminum or zinc) onto the surface of the workpiece to form a metal arc spray coating layer, and then seal it with a highly permeable corrosion-resistant coating to form an arc spray coating. Anti-corrosion composite coating. Its technical characteristics are: 1 long life of anti-corrosion, up to 20 years; 2 high adhesion of coating; 3 good quality coating. The process route: semi-finished product preparation of the inner and outer rings of the bearing → pre-cleaning → pre-protection of the workpiece → sand blasting → arc spraying → sealing treatment, which are described below.
1) Bearing inner and outer ring semi-finished products preparation
In order to ensure the high appearance quality of the yaw bearing, the anti-corrosion spraying process is arranged after all the machining, and the bearing parts after the spraying are directly put into the warehouse after the assembly is completed, so as to ensure that the anti-corrosion layer is not scratched.
2) Pre-cleaning
Degreasing treatment with organic solvents, oil stains may appear on the surface of the semi-finished bearing after machining. In order to ensure the quality of the spray, the cleaning process must be arranged before spraying.
3) Workpiece pre-protection
Protection of the workpiece's arc raceways, threaded holes and surfaces that are not to be sprayed by special surface pre-protection tooling prior to blasting and spraying.
4) Sandblasting
The surface of the inner and outer rings of the bearing is roughened to increase the contact surface between the coating and the workpiece, so that the surface of the workpiece is more activated and the bonding strength of the coating is improved. 5) Arc spraying
Arc spraying (pure aluminum or zinc) equipment mainly includes DC power supply, spray gun, air compressor and air filter, etc. It mainly controls parameters such as arc voltage, current, wire feeding speed, compressed air pressure and spraying distance.
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6) Closed treatment
Since the coated coating has pores, it must be closed to increase corrosion resistance.
The main exposed surface of the yaw bearing after spraying and assembly has a gear surface, a mounting thread surface and a circular raceway surface. The first two are coated with anti-rust oil after assembly, the latter one is coated with lubricating grease during assembly, the inner packaging of the finished product is closed with plastic film, and the outer layer is wrapped with plastic braid to meet the anti-rust requirements.
2 damping torque
2.1 Different formation mechanisms of pitch bearings and yaw bearings
There are two sources of damping torque after yaw bearing assembly: one is the frictional resistance of the raceway part, and the other is the frictional resistance of the sealing strip and the sealing surface. The latter is generally constant under the same processing conditions, so the magnitude of the damping torque after yaw bearing assembly depends mainly on the former.
The frictional resistance torque generated by the raceway portion during rotation mainly depends on the size of the bearing clearance. If the gap is large, the resistance is small, and if the gap is small, the resistance is correspondingly increased. The yaw bearing requires zero clearance or negative clearance, and the amount of negative clearance is determined by the friction damping torque after assembly. Therefore, the friction damping torque after assembly basically depends on the assembly clearance value of the yaw bearing, and the formation of this value depends mainly on the size of the finished car before the quenching of the raceway, the quenching of the raceway surface, and the quenching of the raceway. The grinding size and the size of the rolling elements are matched in four steps.
Wind power bearings (yaw bearings, pitch bearings) are subject to complex forces, and the bearings are subject to large shocks and vibrations. Therefore, bearings are required to withstand both impact and large loads. The life expectancy of wind turbine generators is 20 years, and the cost of bearing installation is relatively large. Therefore, the life of yaw and pitch bearings is required to reach 20 years.
Wind turbines may work in extremely cold areas, with ambient temperatures as low as -400c, bearings operating at around -200C, and bearings must withstand large shock loads at low temperatures.
Yaw and pitch bearings have special requirements in terms of play. Compared with the yaw bearing, the impact load of the pitch bearing is relatively large, and the vibration of the wind blows onto the blade is also large, so the clearance of the pitch bearing is required to be zero clearance or a slight negative clearance value, so that in the case of vibration Lower can reduce the fretting wear of the bearing. The yaw bearing requires a small clearance value.
Wind turbine equipment works in the field, and part of the yaw and pitch bearings are exposed to the outside, and will be polluted by the atmosphere. The high humidity environment will also corrode the bearing base. Therefore, the yaw and pitch bearings exposed outside are eroded. The surface is required to be surface treated.
The difference between pitch bearings and yaw bearings, the above is here, I believe that everyone has a certain understanding of pitch bearings and yaw bearings.
