Case hardened roller cutter for a rotary drill bit and method of making
US4969378A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Oct 13, 1989 |
| Grant date | Nov 13, 1990 |
| Priority date | — |
| Expiry date | Oct 13, 2009 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10S76/12
- WIPO fieldCivil engineering
- WIPO sectorOther fields
Abstract
A roller cutter (28) for a rotary drill bit (10) and method of making, utilizing an ion nitriding hardening process for the external surface (42) and the internal bearing surfaces (33, 34, 38) in the central cavity (30) of the roller cutter (28). The roller cutter (28) is made from a through hardenable steel and the ion nitrided hardened layer (77) has a total thickness less than around 0.030 inch. Hardened layer (77) has a relatively thick inner stratum (80) and a relatively thin outer surface stratum (78). The outer stratum (78) is formed of Fe.sub.4 N having a thickness no greater than around 0.0004 inch to form an outer surface which is ductile and has a relatively low friction coefficient.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.