Bevel Gearbox Bearing Life
The bevel gear is used to convey the movement and power between the two intersecting axes. In general machinery, the angle of intersection between the two axes of the bevel gear is equal to 90 ° (but may not be equal to 90 °). Similar to cylindrical gears, bevel gears have indexed cones, crested cones, root cones and base cones. The cone has a large end and a small end, and its corresponding large end circle is called the index circle (its radius r), the top circle, the tooth circle and the base circle. The movement of a pair of bevel gears is equivalent to a pair of conical chords for pure rolling
In the design of bevel gear drive, according to a given transmission ratio, according to the above formula to determine the value of two rounds of cone angle.
As for the bevel gear tooth tip cone angle and the root of the root cone angle of the size, then with the two bevel gear meshing transmission on the requirements of its top clearance. According to the national standard (GB / T 12369-1990, GB / T12370-1990) regulations, the use of other top-gap bevel gear drive, the two rounds of the top gap from the big end to the small end is equal, The cone of the cone and the cone of the tooth root coincide with one point. But the two rounds of the top of the cone, because of its bus parallel to the other bevel gear with another bevel of the tooth root cone of the bus, so the cone is no longer with the indexing cone cone coincidence. This kind of bevel gear is equivalent to reduce the tooth tip of the small end of the tooth height, thereby reducing the possibility of the tip of the tooth tip; and the radius of the tooth radius is large, is conducive to improving the load bearing capacity, tool life and storage Oil lubrication
The bevel gear box is an important part of the mechanical transmission is widely used in a pair of gear meshing, due to the inevitable existence of the pitch, tooth and other errors in the course of the operation will produce meshing impact occurs with the gear meshing frequency corresponding Noise, friction between the tooth surface due to relative sliding friction occurs. As the gears are the basic parts of the gearbox drive, reducing the gear noise is necessary to control the gearbox noise. In general, the gear system noise occurs mainly in the following areas:
1. gear design aspects. Improper parameter selection, coincidence is too small, improper profile modification or no modification, gear box structure is unreasonable and so on. Gear processing base section error and tooth profile error is too large, the tooth side gap is too large, the surface roughness is too large and so on.
2. Gear train and gearbox. Assembly eccentricity, contact accuracy is low, the parallelism of the shaft is poor, the shaft, the bearing, the bearing rigidity is insufficient, the bearing rotation precision is not high and the gap is not proper.
3. Other aspects of input torque. The fluctuation of the load torque, the torsional vibration of the shaft system, the balance of the motor and other transmission pairs.
Statistics show that the wind turbine gearbox failure is still about 50% of the fault with the bearing selection, manufacturing, lubrication or use. At present, due to technical conditions and other reasons, the domestic megawatt-class unit of the core components such as motors, gear boxes, blades, electronic control equipment and yaw systems, many rely on imports, and used in these large wind turbine gear Box bearings, yaw bearings, pitch bearings and spindle bearings are entirely dependent on imports. Therefore, the more accurate bearing life calculation method is particularly important for the design of wind turbine gearbox.
Due to the high reliability required for bearings, the bearing life is usually not less than 130,000 hours. And because there are too many factors that affect the fatigue life of the bearing, the fatigue life theory of the bearing still needs to be improved, and the bearing life theory at home and abroad does not have a unified calculation method accepted by all the industries.
Bearing operating temperature, lubricating oil viscosity and cleanliness and speed factors such as bearing life has a great impact on the operating state of deterioration (temperature rise, speed reduction, increased pollutants), the bearing life may be significantly reduced. The impact of wind turbine gear box bearing life of various factors in-depth analysis, to develop a more accurate calculation of bearing life is the domestic bearing industry and even the top priority of wind power industry