Taper lock removable stem for raise bit
US3993147A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Jan 19, 1976 |
| Grant date | Nov 23, 1976 |
| Priority date | — |
| Expiry date | Jan 19, 1996 |
Classification
- Technology area (CPC E)Fixed Constructions
- CPC primaryE21B10/28
- WIPO fieldCivil engineering
- WIPO sectorOther fields
Abstract
A raise bit for enlarging a pilot hole into a larger diameter hole by disintegrating the earth formations that surround the pilot hole is provided with a removable drive stem. The removable drive stem allows the raise bit to be transported through small passages and helps extend the useful lifetime of the bit. The bit may be assembled without weakening the highly-stressed, heat-treated stem by welding. The raise bit body includes a multiplicity of rolling cutters for contacting and disintegrating the earth formations surrounding the pilot hole. A central opening extends through the bit body. The central opening includes an upward facing tapered surface. The lower end of the drive stem extends through the central opening. A downward facing tapered surface on the drive stem mates with the upward facing tapered surface on the bit body. The lower end of the drive stem is threaded to receive a threaded nut which draws the tapered surfaces together.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.