Method and apparatus for upwardly cutting full cutting face of a shaft without requesting workmen's hands
US4248312A · kind A · utility
5Cited by
5References
9Claims
0Family size
Assignees
Inventors
Key dates
| Filing date | Apr 10, 1978 |
| Grant date | Feb 3, 1981 |
| Priority date | — |
| Expiry date | Apr 10, 1998 |
Classification
- Technology area (CPC E)Fixed Constructions
- CPC primaryE21B19/086
- WIPO fieldCivil engineering
- WIPO sectorOther fields
Abstract
There is provided a method and apparatus for upwardly excavating a shaft through destructible underground rock. The cutting operation is carried out by full face boring without relying on blasting. An operation for supporting the shaft side wall is carried out by means of frame segments loosely following the advance of the bit. The cutting operation and supporting operation are independent from one another. The diameter of the bit is contracted after the cutting operation to allow the bit to be lowered down through the frame segments.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.