Cold finished seamless steel tubes
US7371293B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Jan 24, 2005 |
| Grant date | May 13, 2008 |
| Priority date | — |
| Expiry date | Jun 16, 2026 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10T428/12458
- WIPO fieldMaterials, metallurgy
- WIPO sectorChemistry
Abstract
Cold finished seamless steel tubes are made such that the residual stress F to be generated at the stage of the correction process after cold working is controlled to be 30 MPa or more and the scattering thereof is 30 MPa or less, when measured by Crampton method. Further, by adjusting the average grain size of spheroidized carbides, the dimensional change which emerges in lathe turning of the outside and inside diameter of relevant steel tubes due to the residual strain can be suppressed, and the strict roundness as well as the excellent machinability can be secured at the final processing stage of the work pieces for bearing parts. Consequently, steel tubes with high dimensional accuracy and less dimensional change at the final steps such as lathe turning, heat treatment and the like, can be made for use as bearing parts.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.