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.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part of application Ser. No. 08/067,298, 72 71, a directional single cone boring bit 1200 is illustrated. The single cone boring bit has a single rotary cutter or cone 1202 similar to those used on prior art tri-cone drilling bits used in the oil field. The jet 1101 discharges against the side of the cutter 1202 to clean debris therefrom. In other aspects, the boring bit 1200 is identical to boring bit 1100 discussed previously and identical elements on the figures are identified by the same reference numerals.

The roller cones described in this invention provide the same cutting action as in the oil field application of the tri-cone bits previously described. These tri-cone bits have one center cut cone and two adjacent cones. However, the addition of the deflecting surface and the removal of one of the adjacent roller cones permits the bit 1100 when thrust forward without rotation to be deflected from the axis of the bore thus permitting the direction of the bore to be altered. The addition of the deflecting surface and the removal of two of the adjacent roller cones permits the bit 1200 when thrust forward without rotation to be deflected from the axis of the bore thus permitting the direction of the bore to be altered. The continuous rotation of the drill bit and application of thrust permits the bore to be in a straight line relative to the drill string axis 1002. The hardness of the material being cut will dictate the amount of steering capable of being accomplished. Some semi-hard materials will permit the oscillating of the bit and the drill string about the central axis of rotation 1002 while applying thrust to change the direction of the bore axis.

The heads 1000, 1050, 1100 and 1200 described have a number of significant advantages over previous known boring heads. The heads 1000, 1050, 1100 and 1200 bore a rounder, straighter hole than a one-sided slanted head which tends to drill more of a helical borehole. The heads 1000, 1050, 1100 and 1200 have proven particularly effective in boring productivity and direction accuracy through sand and rock. With previous one-sided slanted heads, the head could impact and catch on a hard object, causing the boring rods in the drill string to wind up in torsion until the head breaks free of the object with a sudden release. The heads 1000, 1050, 1100 and 1200 appear to alleviate this problem.

The additional advantages of heads 1000, 1050, 1100 and 1200 include an improvement in the directional accuracy of the head through rock and other hard boring conditions. The boring head also uses less water to cool the bit which has significant advantages as EPA regulations for disposal of drilling fluids are becoming more difficult to comply with. The presence of the blades also reduces a tendency for the head to roll when pushed forward without rotation to make a directional change. Finally, the head provides an improved ease of surface launch.

While the invention has been described with a certain degree of particularity it is manifest that many changes may be made in the details of construction and arrangement of components without departing from the spirit and scope of this disclosure. It is understood that the invention is not limited to the embodiments set forth herein for purposes of exemplification, but is to be limited only by the scope of the attached claim or claims, including the full range of equivalency to which each element thereof is entitled.

Claims

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 one a 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.