Methods and apparatus for masking a percussive drill member prior to a surface treatment thereof
US6238489A · kind A · utility
4Cited by
6References
5Claims
0Family size
Assignee
Inventor
Key dates
| Filing date | Sep 10, 1998 |
| Grant date | May 29, 2001 |
| Priority date | — |
| Expiry date | Sep 10, 2018 |
Classification
- Technology area (CPC E)Fixed Constructions
- CPC primaryE21B17/0426
- WIPO fieldCivil engineering
- WIPO sectorOther fields
Abstract
A metallic drilling member is surface hardened except at an end portion, because the end portion is masked. The masking is achieved by placing on the end portion a lid which forms a slight gap around the surface being heat treated. During the heat treatment a furnace atmosphere enters the gap to cause the depth of the heat treatment to be gradually decreased in a manner producing a relatively elongated transition zone between heat treated and non-heat treated portions of the surface. The gap can be of constant width, or gradually decreasing width.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.