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US 8,844,140 B2Granted
Rolling bearing of ceramic and steel engaging parts
AssigneeSchaeffler Technologies AG & Co. KG
InventorsOskar Beer, Franz-Josef Ebert, Gerhard Kreiselmeier, Edgar Streit
Life of this patent
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Abstract
A roller bearing having two cooperating rolling parts of which one is of ceramic and the other of a steel. The steel part is of such structure and/or material and/or is so produced to cause residual compressive stresses to form beneath the contact surface of the steel part, at least in a load-free state, down to a depth.
Claims3
A method of producing a steel rolling part of a roller bearing, the method comprising:
- hardening the steel rolling part by a first hardening heat treating and tempering;
- and
- subjecting the steel rolling part to a thermo-chemical heat treatment, following the tempering, by plasma nitriding an outer layer of the steel rolling part at a temperature of at least 400° C. so that compressive stresses in a martensitic microstructure of the steel rolling part of at least 300 MPa for a load-free outer layer of the steel rolling part from a surface to a depth of 40 μm from the surface are created and so that the outer layer has a hardness of at least 800 HVO.3 at a depth of about 0.2 mm from the surface,
- wherein the tempering is performed at a temperature higher than the nitriding.
1 more element
Dependencies are inferred from the claim text.