Claims
- 1. A method for controlling a drilling apparatus for drilling a bore hole through a medium, said apparatus having a drill string terminating at a drill head which rotates about an axis of rotation, said drill head including a cutting member selected to cut at a point offset from said axis, said apparatus including means for longitudinally advancing said drill head, said method comprising:
- advancing said drill head in a desired direction angled away from a straight path by:
- a. applying a longitudinal force to said drill head when said cutting member is in an arc of rotation through which said desired direction passes; and
- b. relaxing said longitudinal force and longitudinally retracting said drill head when said cutting member is outside of said arc of rotation.
- 2. A method according to claim 1 comprising selecting said arc of rotation for said desired direction to bisect said arc of rotation.
- 3. A method according to claim 1 wherein said arc of rotation is between 0 degrees and 180 degrees.
- 4. A method according to claim 3 wherein said arc of rotation is 120 degrees.
- 5. A method according to claim 2 wherein said arc of rotation is between 0 degrees and 180 degrees.
- 6. A method according to claim 5 wherein said arc of rotation is 120 degrees.
- 7. A method according to claim 1 wherein said longitudinal force is selected for said cutting member to be applied against said medium to be drilled within a prescribed range of pressure for said cutting member to remove waste from said medium at a terminal end of said bore hole.
- 8. A method according to claim 1 wherein said retracting includes retracting said cutting member away from a face of said medium at a terminal end of said bore hole by an amount selected for said cutting member to avoid substantial cutting of said medium when said cutting member is outside of said arc of rotation.
- 9. A method according to claim 1 wherein said drill string includes an exterior end exposed out of said bore hole and mounted on a drive system for longitudinally advancing and rotating said drill string, said applying of said force including advancing said exterior end with said drive system.
- 10. A method according to claim 9 wherein said rotating includes rotating said exterior end with said drive system.
- 11. A method according to claim 1 wherein said drill string includes an exterior end exposed out of said bore hole and mounted on a drive system for rotating said drill string and for longitudinally advancing, relaxing, and retracting said drill head.
- 12. A method according to claim 1 wherein said rotating includes rotating said exterior end with said drive system.
- 13. A method according to claim 12 wherein said retracting includes retracting said exterior end with said drive system.
- 14. A method according to claim 1 wherein said drill string includes an exterior end exposed out of said bore hole and mounted on a drive system for rotating said drill string, a rotational position of said drill head determined by monitoring an amount of rotation of said exterior end by said drive system.
- 15. A method according to claim 9 wherein a rotational position of said drill head is determined by monitoring an amount of rotation of said exterior end by said drive system.
- 16. A method according to claim 9 wherein a rotational position of said drill head is determined by monitoring signals from said drill head indicating said rotational position.
- 17. A method according to claim 15 wherein said drill string includes a plurality of drill string segments sequentially joined at said drive system exterior of said bore hole, said method including measuring an actual rotational position of said drill head following addition of a segment to said drill string and subsequently determining a rotational position of said drill head by monitoring a subsequent amount of rotation of said exterior end by said drive system.
- 18. A method according to claim 1 further comprising repeatedly performing said applying, said relaxing, and said retracting, and still further comprising longitudinally advancing said drill head during said repetition for said drill head to be deflected toward said desired direction during said advancing by opposing surfaces of said medium defining said bore hole.
- 19. A method according to claim 18 wherein said cutting member is selected to cut waste from said medium at a terminal end of said bore hole with a remaining portion of said medium presenting a cam surface on a side of said bore hole opposite said desired direction, said method further including:
- cutting said medium during said applying of said force to form said cam surface; and
- performing said longitudinal advancing for a cam follower on said drill string adjacent said drill head acting against said cam surface to deflect said drill head toward said desired direction as said drill head is longitudinally advanced.
- 20. A method according to claim 1 further comprising repeatedly performing said applying and said retracting and still further comprising longitudinally advancing said drill head following said retracting for said drill head to be deflected toward said desired direction during said advancing with said drill head deflected by opposing surfaces of said medium defining said bore hole.
- 21. A method according to claim 1 comprising advancing said drill head along said straight path by simultaneously rotating said drill head and applying a longitudinal force to said drill head.
- 22. A method according to claim 1 comprising advancing said drill head along said straight path by simultaneously rotating said drill head and applying a longitudinal force to said drill head.
- 23. A method according to claim 19 wherein said cutting member is selected to cut waste from said medium at a terminal end of said bore hole with a remaining portion of said medium presenting a cam surface on a side of said bore hole opposite said desired direction, said method further including:
- cutting said medium during said applying of said force to form said cam surface; and
- performing said longitudinal advancing for a cam follower on said drill string adjacent said drill head acting against said cam surface to deflect said drill head toward said desired direction as said drill head is longitudinally advanced.
- 24. A method according to claim 1 comprising continuing rotation of said drill head during said retracting.
- 25. A method according to claim 1 comprising ceasing rotation of said drill head during at least a portion of said retracting and subsequently resuming rotating of said drill head to angularly position said drill head at a beginning point of said arc of rotation.
- 26. A drilling apparatus for drilling a bore hole through a medium, said apparatus comprising: a drill string terminating at a drill head within said bore hole;
- a drive system exterior of said bore hole for engaging an exterior end of said drill string, said drive system having a first actuator for rotating said drill string about an axis of rotation coincident with a longitudinal axis of said drill string, and a second actuator for longitudinally advancing said drill head;
- said drill head including a cutting member selected to cut at a point offset from said axis; and
- a controller that controls advancement of said drill head in a desired direction angled away from a straight path, wherein said controller controls
- said first and second actuators to apply a longitudinal force to said drill head when said cutting member is in an arc of rotation through which said desired direction passes, and
- further controls said second actuator to relax said longitudinal force and retract said drill string when said cutting member is outside of said arc of rotation.
- 27. A drilling apparatus according to claim 26 wherein said controller controls said second actuator to retract said drill string for said drill head to be moved away from a terminal end of said bore hole.
- 28. A drilling apparatus according to claim 26 wherein said cutting member is selected to cut waste from said medium at a terminal end of said bore hole with a remaining portion of said medium presenting a cam surface on a side of said bore hole opposite said desired direction.
- 29. A drilling apparatus according to claim 28 wherein said drill string includes a cam follower positioned on a side thereof to act against said cam surface to deflect said drill head toward said desired direction as said drill head is longitudinally advanced.
Parent Case Info
This is a continuation-in-part of application Ser. No. 08/618,541, filed Mar. 4, 1996, now abandoned.
US Referenced Citations (33)
Foreign Referenced Citations (3)
Number |
Date |
Country |
0209217 |
Jul 1991 |
EPX |
0 467 642 A2 |
Jan 1992 |
EPX |
53-114286 |
Jun 1981 |
JPX |
Continuation in Parts (1)
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Number |
Date |
Country |
Parent |
618541 |
Mar 1996 |
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