Metal pipe having thickened end portion, and method of manufacturing same
US10514113B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Feb 18, 2016 |
| Grant date | Dec 24, 2019 |
| Priority date | — |
| Expiry date | Apr 14, 2036 |
Classification
- Technology area (CPC B)Performing Operations; Transporting
- CPC primaryB21D53/88
- WIPO fieldMachine tools
- WIPO sectorMechanical engineering
Abstract
A metal pipe having a thickened end portion, the metal pipe includes: when viewed in a longitudinal direction of the metal pipe, a thin portion which has a thickness t0; a first thickened portion which is provided on one end and has a thickness T which is larger than the thickness t0; and a first taper portion which is provided between the thin portion and the first thickened portion and has the thickness which gradually increases from t0 to T; when a hardness of an inner surface of the first thickened portion is measured in a circumferential direction and the hardness is plotted with respect to a position in the circumferential direction, in which a waveform representing a high hardness portion having a hardness which is 95% or more of a maximum hardness in the circumferential direction and a waveform representing a low hardness portion having a hardness which is less than 95% of the maximum hardness alternately appear, and a plurality of combinations of the waveform representing the high hardness portion and the waveform representing the low hardness portion appear.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.