SLEWING BEARING FOR WIND TURBINES

The slewing bearing is the core component of the wind turbine and is widely used in the pitch and yaw systems of wind turbines. The pitch bearings are used to connect the wheel and the blades, and the yaw bearings are used to connect the tower and the unit. The wind power slewing bearing industry has experienced decades of development in China and has developed a comprehensive development capability for bearing design, manufacturing and testing. Wind power slewing bearing is a kind of green resource. For traditional bearings, it has better product potential. With the country's emphasis on green products, the future of wind power bearings is more advantageous and has a lot of room for development.

Wind power bearings include a wide variety of bearings, mainly divided into slewing bearings (slewing bearings), cylindrical roller bearings, spherical roller bearings and tapered roller bearings, and slewing bearings are an important part of the entire wind power equipment, slewing bearings Generally there are single row four point contact ball type (01 series, 02 series, 13series), double volleyball type (02 series), double row ball type (07 series), single row cross roller type (11 series), three rows Roller type (13 series), ball and column combination six series, in which single row four point contact ball type slewing bearing has lower cost and higher comprehensive performance; double row ball type slewing bearing has long service life and strong carrying capacity The resistance is small, the wear amount is large, the requirement for the mounting base is not high, but the movement precision is low; the cross roller type slewing bearing has high precision, long service life and high dynamic load capacity, but the rigidity and precision of the base are relatively high. High requirements, and the edge effect is easy to occur when the roller and the raceway are in contact, resulting in the actual stress of the edge is much larger than the design stress; the three-row roller slewing bearing generally has a very high static load carrying capacity. The pitch slewing bearing adopts double-row four-point contact ball slewing bearing. The yaw slewing bearing adopts single-row four-point contact ball slewing bearing, and a small number of cross-roller slewing bearing or other forms.

Wind power slewing bearing mainly has four major features. It is used under harsh natural conditions; it bears several kinds of loads, not only to withstand axial force, radial force, but also to withstand large overturning moment; high maintenance cost, disassembly and maintenance is extremely difficult; longer Service life, generally requires more than 20 years; high reliability; from design to production, the slewing bearing requirements are more stringent than other industries. Therefore, we use 42CrMo material for the characteristics of wind power slewing bearing, and the medium-frequency quenching after quenching and tempering improves the surface hardness and maintains the toughness of the core. The surface hardness is generally required to be above 58HRC, and the depth of the hardened layer is generally controlled at 3.5-5.0mm. Strictly in accordance with relevant national industry standards (JB/T2300-1999) such as tensile strength, yield strength, reduction of area, elongation, hardness, etc., special attention should be paid to the process of processing wind power slewing:

1. To control the forging temperature, Do not coarsen the grain;

2. Control the process of the modulation quality to ensure the quenched and tempered structure of the core to ensure its mechanical properties;

3. Control the depth of the intermediate frequency quench hardened layer on the surface;

4. Avoid micro-cracks on the surface.

Wind mill market is known as the most stringent and challenging requirement setter in the modern industrial world. Wind direction, environmental constraints, high reliability, extremely long life span are requirements that call for an extremely deep understanding of the application in its whole and the ability to fine tune on the finest detail. La Leonessa slewing rings are designed according to the experience accumulated in this field and  to international rules. Equipped with internal greasing channels to guarantee a continue lubrification of the rolling elements, La Leonessa slewing rings are used in the pitch and yaw positions.