Innovation for airy heights: Harder slewing bearings for more efficient wind turbines

The demand for energy is growing worldwide. Thanks to an innovative patent, our slewing bearings defy the forces of nature and support the production of sustainable electricity.

For the fifth time in a row thyssenkrupp is among the 100 most active companies in the ranking of the European Patent Office. In 2019 alone the group filed more than 600 patent applications worldwide. This innovative strength and the aim of developing tomorrow's technologies already today is what drives the experts at thyssenkrupp rothe Erde. Their process for manufacturing a bearing ring for slewing bearings using induction hardening is one of more than 22,000 innovations protected by patents in the company's 125-year history.

While fossil fuels are becoming increasingly scarce, the demand for energy is growing worldwide. Limited resources and rising energy prices are global challenges and an inspiration for our experts at thyssenkrupp rothe erde to create innovative solutions. As resilient components, slewing bearings and rings in wind turbines, hydroelectric and tidal power plants and solar energy systems make a significant and sustainable contribution to global resource conservation and climate protection.

To make large-diameter bearings particularly resistant to their use amid the forces of nature and to prepare them for all axial and radial forces acting on them, our experts have developed a special process to increase the hardness of the bearing rings. The patent “Method for the production of a bearing ring for large-size rolling bearings” with the file number PCT/EP2006/001266 describes how a bearing ring is heated in the electric field of an inductor during its manufacturing and then cooled – thus obtaining a high degree of hardness over its entire surface.

While earlier processes already used two counter-rotating inductors for hardening bearing rings, that were moved over the bearing ring in the feed process, they reheated an already hardened area when the inductors met again. The result: a so-called slip – a small segment that is incompletely hardened due to the process and where the bearing ring remains softer.

The solution from thyssenkrupp experts: In an automated process, at least two induction coils uniformly heat the bearing ring to hardening temperature. In addition to the two coils, a third induction coil is provided which, through swinging movements, ensures a uniform heating zone and constant heating depth in the slip area. Moving sprinklers attached to the two induction coils can then cool the material evenly.

Through these coordinated movements, the process achieves a uniform and common heating surface. Coordinated cooling prevents slippage.

thyssenkrupp's patent department is one of the oldest in the country. Each year the colleagues protect around 600 new innovations through patents. Dr. Stephan Wolke, CEO of the central patent department explains the work of the intellectual property team on engineered.