HOLLOW SPRING AND ITS MANUFACTURING METHOD Russian patent published in 2023 - IPC F16F1/02 

FIELD: mechanical engineering.

SUBSTANCE: hollow spring contains a steel pipe, in which residual compressive stress directed in an axial direction of the steel pipe is applied to part of an inner surface of the steel pipe for reduction in extending stress directed in the axial direction of the steel pipe, arising when applying a load to the steel pipe. Moreover, the specified part contains an inner surface of a bended part of the steel pipe, in which extending stress is concentrated, when applying a load to the hollow spring. A method for the manufacture of a hollow spring is also claimed, providing for: provision of a steel pipe and application of a compressive force to part of an outer surface of the steel pipe from a direction along a circumference to impart residual compressive stress to part of the inner surface of the steel pipe. Operating time to fatigue failure of the steel pipe is prolonged due to impart to the inner surface of residual compressive stress of the steel pipe. A spring made by the specified method is also claimed.

EFFECT: prolonged operating time to fatigue failure is provided.

12 cl, 14 dwg, 2 tbl