Directional multi-blade boring head

Abstract

Directional boring bits ( 1100, 1200 ) are disclosed which have at least one roller cone ( 1202, 1104 ) and also each define a deflecting surface ( 1104 ) for deflecting the boring bit when the bit is advanced without rotation. The borehole can be curved by pushing the bit forward without rotation.

We claim:  
     
       1. A directional boring head for a boring machine, the boring machine capable of axially advancing and rotating a drill string about an axis of rotation underground, the drill string ending in the directional boring head, said directional boring head comprising: 
       a body having a central axis of rotation;  
       a deflection structure mounted on the body defining a deflecting surface at an oblique angle to the central axis of rotation of the body;  
       at least onea single roller cone mounted to said body; and  
       the deflecting surface deflecting the boring head as the boring machine advances the drill string without rotation and the directional boring head drilling a relatively straight borehole as the boring machine advances the drill string with rotation.  
     
     
       2. The direction boring head of claim  1  having two roller cones mounted on the body. 
     
     
       3. The directional boring head of claim  1  wherein a fluid jet is mounted on the body, the body having a passage for flow of fluid for discharge from the jet to assist in the drilling. 
     
     
       4. The directional boring head of claim  3  wherein the jet is oriented to discharge a fluid at the roller cone. 
     
     
       5. The directional boring head of claim  1  wherein the deflection structure and roller cone are mounted on a bit assembly removably attached to the body. 
     
     
       6. The directional boring head of claim  1  wherein the rotational axis of the roller cone intersects the central axis of rotation of the body. 
     
     
       7. The directional boring head of claim  1  having one roller cone mounted on the body.