Guided earth boring tool
US4858704A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Sep 9, 1987 |
| Grant date | Aug 22, 1989 |
| Priority date | — |
| Expiry date | Sep 9, 2007 |
Classification
- Technology area (CPC E)Fixed Constructions
- CPC primaryE21B7/26
- WIPO fieldCivil engineering
- WIPO sectorOther fields
Abstract
Long utility holes, for gas lines, electrical conduit, communications conduit and the like, may be bored or pierced horizontally through the earth, particularly under obstacles, such as buildings, streets, highways, rivers, lakes, etc. Such holes may be bored by an underground drilling mole (underground percussion drill) supported on a hollow drill rod and supplied with compressed air through the rod to operate an air hammer which strikes an anvil having an external boring face, preferably constructed to apply an asymmetric boring force. The drill rod is operated by a drill rig on the surface or recessed in special pit for horizontal drilling and provides for additional sections of pipe or hollow rod as the boring progresses. The asymmetric boring force causes the boring path to curve and, when straight line drilling is needed, the drill rod is rotated to counteract the asymmetric boring force. An alternative boring tool utilizes an expander supported on a solid or hollow drill rod and having a base end supported on and larger in diameter than the rod and tapering longitudinally forward therefrom. It may have a uniform extension protruding a short distance forward. The tool penetra…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.