Drill rod and method for its manufacture
US5988301A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Jun 20, 1997 |
| Grant date | Nov 23, 1999 |
| Priority date | — |
| Expiry date | Jun 20, 2017 |
Classification
- Technology area (CPC E)Fixed Constructions
- CPC primaryE21B17/0426
- WIPO fieldCivil engineering
- WIPO sectorOther fields
Abstract
A rock drilling rod is manufactured by placing free ends of first and second hollow rod components in abutment, and establishing relative rotation between the free ends to friction weld those free ends together. The first component comprises a thread and a clearance portion disposed adjacent the thread. The first component has a hot hardness value of at least about 170 HV1 at 600.degree. C. Prior to friction welding the components together, the thread, clearance portion and central passage of the first component are nitrocarburized against corrosion fatigue. Following the nitrocarburizing, the core hardness is at least 440 HV1. Following the welding, the weld is cooled while keeping a core hardness of the respective portions of the first and second components disposed immediately adjacent the weld no lower than 390 HV1.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.