Claims
- 1. A drill head for an apparatus for directional boring, comprising:
a bit; a holder for a device for detecting angular orientation of the bit; a hammer including a striker for delivering impacts to the bit; wherein the bit assembly, holder and hammer are connected head to tail with the bit at a front end; and wherein the bit has a frontwardly facing main cutting surface having a plurality of main cutting teeth disposed thereon and a gage tower extending radially outwardly from the main cutting surface, which gage tower has at least one frontwardly facing gage cutting tooth thereon suitable for cutting over an angle defined by less than a fill rotation of the bit, and the device for detecting angular orientation is in a predetermined alignment with the gage tower so that it determines the orientation of the gage tower relative to the axis of rotation of the drill head.
- 2. The drill head of claim 1, wherein the main, forwardly facing cutting surface is substantially flat and circular and lies in a plane perpendicular to a longitudinal axis of rotation of the bit.
- 3. The drill head of claim 1, wherein the main cutting surface of the bit has fluid ejection ports thereon, and the drill head has a passage for conducting a drill fluid therethrough to the ejection port.
- 4. The drill head of claim 1, wherein the bit has a heel on an outer side surface thereof at a position opposite the gage tower, which extends radially outwardly further than the radially outermost cutting tooth on the main cutting surface located on the opposite side of the main cutting face from the gage tower.
- 5. The drill head of claim 4, wherein at least a front portion of the heel slopes inwardly from back to front.
- 6. The drill head of claim 4, wherein the heel is parallel to an axis of rotation of the bit.
- 7. The drill head of claim 5, wherein at least a front portion of the heel slopes inwardly from back to front at an angle in the range of from about 1° to 15°.
- 8. The drill head of claim 1, wherein the main cutting teeth and the gage cutting tooth comprise carbide studs.
- 9. The drill head of claim 1, wherein the gage tower comprises a radial projection adjoining the main cutting surface, and a plurality of gage cutting teeth extend from a front surface of the gage tower, such that the gage cutting teeth describe a larger circle than any of the main cutting teeth on the main cutting surface when the bit rotates.
- 10. The drill head of claim 9, wherein the gage tower defines an angle of from about 45 to 90 degrees relative to the lengthwise axis of the drill head, and the positions of the gage cutting teeth define an arc.
- 11. The drill head of claim 9, wherein the gage tower is arc-shaped and has a front surface substantially coplanar with the main cutting surface.
- 12. The drill head of claim 10, wherein the main cutting teeth comprise carbide studs and the gage cutting teeth comprise carbide studs.
- 13. The drill head of claim 3, wherein the bit has a plurality of fluid ejection ports and corresponding passages for conducting a drill fluid, and further has a plurality of grooves in the main cutting surface thereof offset from the main cutting teeth, which grooves extend from the ejection ports to an outer peripheral edge of the main cutting face and are configured for channeling pressure fluid away from the main cutting face.
- 14. The drill head of claim 1, further comprising a connection for mounting the bit ahead of the hammer to receive impacts from the hammer.
- 15. A drill bit for an apparatus for directional boring, comprising a bit body having:
a frontwardly facing main cutting surface having a plurality of main cutting teeth disposed thereon; a gage tower extending radially outwardly from the main cutting surface, which gage tower has at least one frontwardly facing gage cutting tooth thereon suitable for cutting over an angle defined by less than a full rotation of the bit; a heel on an outer side surface of the bit body at a position opposite the gage tower, which heel extends radially outwardly further than the radially outermost cutting tooth on the main cutting surface located on the opposite side of the main cutting face from the gage tower; fluid ejection ports on the main cutting surface of the bit; and passages in the bit body for conducting a drill fluid therethrough to the ejection ports.
- 16. The drill bit of claim 15, wherein the main cutting surface is substantially flat and circular and lies in a plane perpendicular to a longitudinal axis of rotation of the bit.
- 17. The drill bit of claim 15, wherein at least a front portion of the heel slopes inwardly from back to front.
- 18. The drill bit of claim 17, wherein the heel is parallel to an axis of rotation of the bit.
- 19. The drill bit of claim 17, wherein at least a front portion of the heel slopes inwardly from back to front at an angle in the range of from about 1° to 15°.
- 20. The drill bit of claim 15, wherein the main cutting teeth and the gage cutting tooth comprise carbide studs.
- 21. The drill bit of claim 15, wherein the gage tower comprises a radial projection adjoining the main cutting surface, and a plurality of gage cutting teeth extend from a front surface of the gage tower, such that the gage cutting teeth form an arc and describe a larger circle than any of the main cutting teeth on the main cutting surface when the bit rotates.
- 22. The drill bit of claim 21, wherein the gage tower defines an angle of from about 45 to 90 degrees relative to an axis of rotation of the drill bit.
- 23. The drill bit of claim 21, wherein the gage tower is arc-shaped and has a front surface substantially coplanar with the main cutting surface.
- 24. The drill bit of claim 15, wherein the bit has grooves in the main cutting surface thereof offset from the main cutting teeth, which grooves extend from the ejection ports to an outer peripheral edge of the main cutting face and are configured for channelling pressure fluid away from the main cutting face.
- 25. A method for directional boring using a directional boring machine which can push and rotate a drill string having a drill head mounted thereon, wherein the drill head includes a bit, a holder for a device for detecting angular orientation of the bit, and a hammer including a striker for delivering impacts to the bit, wherein the bit assembly, holder and hammer are connected head to tail with the bit at a front end, and wherein the bit has a frontwardly facing main cutting surface having a plurality of main cutting teeth disposed thereon and a gage tower extending radially outwardly from the main cutting surface, which gage tower has at least one frontwardly facing gage cutting tooth thereon suitable for cutting over an angle defined by less than a full rotation of the bit, and the device for detecting angular orientation is in a predetermined alignment with the gage tower so that it determines the orientation of the gage tower relative to the axis of rotation of the drill head, comprising the steps of:
boring straight through a medium by pushing and rotating the drill head with the drill string while delivering impacts to the bit with the hammer; prior to changing the boring direction, determining the angular orientation of the gage tower using the device for detecting angular orientation; and changing direction during boring by pushing and rotating the bit repeatedly over an angle defined by less than a full rotation of the bit while delivering impacts to the bit with the hammer, so that the drill head deviates in the direction of the cutting action of the gage tower.
- 26. The method of claim 25, further comprising performing the steps of boring straight and changing direction in both soil and rock during the same boring run using the same bit.
- 27. The method of claim 25, wherein the angle less than a full rotation of the drill bit is in the range of 45 to 240 degrees.
- 28. The method of claim 25, wherein the angle less than a full rotation of the drill bit is in the range of 180 to 240 degrees.
- 29. The method of claim 25, wherein the medium is rock.
- 30. The method of claim 25, wherein the medium includes hard rock having a compressive strength greater than 18,000 psi.
- 31. The method of claim 25, further comprising feeding a pressure fluid through the drill string and holder for the device for determining angular orientation into the hammer, wherein the pressure fluid actuates a striker in the hammer that delivers impacts that are transmitted to the bit, and spent pressure fluid is exhausted through a fluid passage in the bit out of a port on the main cutting face.
- 32. A method for directional boring in mixed conditions including both soil and rock using a directional boring machine which can push and rotate a drill string having a drill head mounted thereon, wherein the drill head includes a bit, a holder for a device for detecting angular orientation of the bit, and a hammer including a striker for delivering impacts to the bit, wherein the bit assembly, holder and hammer are connected head to tail with the bit at a front end, and wherein the bit has a frontwardly facing main cutting surface having a plurality of main cutting teeth disposed thereon and a gage tower extending radially outwardly from the main cutting surface, which gage tower has at least one frontwardly facing gage cutting tooth thereon suitable for cutting over an angle defined by less than a full rotation of the bit, and the bit has a heel on an outer side surface thereof at a position opposite the gage tower, which heel extends radially outwardly further than the radially outermost cutting tooth on the main cutting surface located on the opposite side of the main cutting face from the gage tower and at least a front portion of the heel slopes inwardly from back to front, and wherein the device for detecting angular orientation is in a predetermined alignment with the gage tower so that it determines the orientation of the gage tower relative to the axis of rotation of the drill head, comprising the steps of:
boring straight through soil by pushing and rotating the drill head with the drill string; boring straight through rock by pushing and rotating the drill head with the drill string while delivering impacts to the bit with the hammer; prior to changing the boring direction in either soil or rock, determining the angular orientation of the gage tower using the device for detecting angular orientation; changing direction when boring in rock by pushing and rotating the bit repeatedly over an angle defined by less than a full rotation of the bit while delivering impacts to the bit with the hammer, so that the drill head deviates in the direction of the cutting action of the gage tower; and changing direction when boring in soil by pushing the bit with the drill string without rotating it so that the drill head deviates in a direction of the gage tower and away from the heel.
- 33. The method of claim 32, further comprising delivering impacts to the bit with the hammer with boring straight through soil.
- 34. The method of claim 33, wherein the rock includes hard rock having a compressive strength of at least 18,000 psi.
- 35. The method of claim 33, wherein the drill bit has fluid ejection ports on the main cutting surface of the bit and passages in the bit body for conducting a drill fluid therethrough to the ejection ports.
- 36. The method of claim 35, wherein the main cutting teeth and gage cutting tooth comprise carbide studs.
- 37. The method of claim 32, wherein the angle less than a full rotation of the drill bit is in the range of 45 to 240 degrees.
Parent Case Info
[0001] This application is a conversion of U.S. Provisional Application No. 60/122,593, filed Mar. 3, 1999, incorporated by reference herein and relied upon for priority.
Provisional Applications (1)
|
Number |
Date |
Country |
|
60122593 |
Mar 1999 |
US |
Continuations (1)
|
Number |
Date |
Country |
Parent |
09517967 |
Mar 2000 |
US |
Child |
09957412 |
Sep 2001 |
US |