Claims
- 1. A controllable tool for drilling holes in soft earth comprising
- an elongated rigid supporting drill rod or pipe,
- means supporting said drill rod or pipe for earth boring or piercing movement, including
- means for moving said drill rod or pipe longitudinally for penetrating the earth,
- means for rotating said drill rod or pipe while penetrating the earth, and
- means for controlling the direction of movement of said drill rod or pipe along a straight or curved path,
- said drill rod or pipe moving and rotating means being constructed to permit addition and removal of supporting drill rod or pipe during earth penetrating operation,
- an earth piercing member of substantially cylindrical shape,
- said tool being operable to penetrate the earth upon longitudinal movement of said drill rod or pipe by said longitudinal rod or pipe moving means, and
- said direction controlling means comprising means causing drill rod or pipe movement in a curved path through the earth when said rod or pipe is not rotated and causing drill rod or pipe straight line movement when said rod or pipe is rotated.
- 2. A controllable earth drilling tool according to claim 1 in which
- said cylindrical earth piercing member has an inclined plane as a forwardly extending face penetrating the earth on forward movement and operable to control the path of movement by reaction against the earth through which the tool is moved and effects a curved movement when not rotated and a substantially straight movement when rotated in a selected manner.
- 3. A controllable earth drilling tool according to claim 2 in which
- said drill rod or pipe rotating means is operable to rotate said drill rod or pipe to rotate said inclined plane face in the earth to permit said tool to penetrate the earth in a straight line movement when moved longitudinally by said drill rod or pipe moving means.
- 4. A controllable earth drilling tool according to claim 3 in which
- said tool is adapted to be operated from a pit or hole in the earth to drive said drill rod or pipe longitudinally therefrom and is adapted to be driven by driving means positioned therein.
- 5. A method of drilling holes in soft earth comprising
- providing an elongated rigid supporting drill rod or pipe with a substantially cylindrical piercing member supported thereon,
- said piercing member including means permitting straight line boring movement when in one position and curved line boring movement when in another position,
- moving said drill rod or pipe longitudinally without substantial rotation to pierce the earth longitudinally with said piercing member, and
- controlling the direction of movement of said drill rod or pipe from outside the hole being bored by moving said piercing member to said one position or said other position.
- 6. A method of drilling according to claim 5 in which said step of controlling the direction of movement of said drill rod or pipe comprises providing means to cause the same to move in a curved path through the earth when said rod or pipe is not rotated and to cause drill rod or pipe straight line movement when said rod or pipe is rotated in a selected manner, and
- rotating said drill rod or pipe in said selected manner to control drill rod or pipe movement selectively between a straight path and a curved path.
- 7. A method of drilling according to claim 6 in which
- said cylindrical piercing member has an inclined plane as a forwardly extending face to control the path of movement by reaction against the earth through which the tool is moved,
- said step of controlling the direction of movement of said drill rod or pipe comprises rotating said drill rod or pipe from its base end to rotate said inclined plane face in said selected manner to permit said tool to penetrate the earth in a straight line movement when moved longitudinally into the earth.
- 8. A method of drilling according to claim 7 including the steps of
- digging a pit or hole in the earth,
- providing means in said pit or hole for moving said rod or pipe and operating the same to force said tool into the earth.
- 9. A method of drilling according to claim 5 including the steps of
- forcing said tool into the earth from the surface and moving said tool in a curved path beneath an intervening obstacle and back to the surface beyond such obstacle.
CROSS REFERENCE TO RELATED PATENT APPLICATIONS
This application is a continuation of copending application Ser. No. 863,957 filed May 16, 1986, now U.S. Pat. No. 4,694,913.
1. FIELD OF THE INVENTION
This invention relates to new and useful improvements in earth boring tools and more particularly to improved tools for boring more or less horizontally through the earth for laying utility lines, such as gas lines, electrical or communications conduit, etc.
2. Brief Description of the Prior Art
Utility Companies often find it necessary to install or replace piping beneath different types of surfaces such as streets, driveways, railroad tracks, etc. To reduce costs and public inconvenience by eliminating unnecessary excavation and restoration, utilities sometimes use underground boring tools to install the new or replacement pipes. Existing boring tools are suitable for boring short distances (up to 60 ft.), but are not sufficiently advanced to provide directional control for longer distances. This lack of control, coupled with the inability of these tools to detect and steer around obstacles, has limited their use to about 20% of all excavations, with the majority of the remaining excavations being performed by opencut trenching methods.
Therefore, the development of an economic, guided, horizontal boring tool would be useful to the utility industry, since it would significantly increase the use of boring tools by removing the limitations of poor accuracy and by reducing the occurrence of damage to in-place utilities. Use of such a tool instead of open-cut methods, particularly in developed areas, should result in the savings of millions of dollars annually in repair, landscape restoration and road resurfacing costs.
Conventional pneumatic and hydraulic percussion moles are designed to pierce and compact compressible soils for the installation of underground utilities without the necessity of digging large launching and retrieval pits, open cutting of pavement or reclamation of large areas of land. An internal striker or hammer reciprocates under the action of compressed air or hydraulic fluid to deliver high energy blows to the inner face of the body. These blows propel the tool through the soil to form an earthen casing within the soil that remains open to allow laying of cable or conduit.
From early 1970 to 1972, Bell Laboratories, in Chester, New Jersey, conducted research aimed at developing a method of steering and tracking moles. A 4-inch Schramm Pneumagopher was fitted with two steering fins and three mutually orthogonal coils which were used in conjunction with a surface antenna to track the position of the tool. One of these fins was fixed and inclined from the tool's longitudinal axis while the other fin was rotatable.
Two boring modes could be obtained with this system by changing the position of the rotatable fin relative to the fixed fin. These were (1) a roll mode in which the mole was caused to rotate about its longitudinal center line as it advanced into the soil and (2) a steering mode in which the mole was directed to bore in a curved path.
The roll mode was used for both straight boring and as a means for selectively positioning the angular orientation of the fins for subsequent changes in the bore path. Rotation of the mole was induced by bringing the rotatable fin into an anti-parallel alignment with the fixed fin. This positioning results in the generation of a force couple which initiates and maintains rotation.
The steering mode was actuated by locating the rotatable fin parallel to the fixed fin. As the mole penetrates the soil, the outer surfaces of the oncoming fins are brought into contact with the soil and a "slipping wedge" mechanism created. This motion caused the mole to veer in the same direction as the fins point when viewed from the back of the tool.
Published information on the actual field performance of the prototype appears limited to a presentation by J. T. Sibilia of Bell Laboratories to the Edison Electric Institute in Cleveland, Ohio on Oct. 13, 1972. Sibilia reported that the system was capable of turning the mole at rates of 1 to 1.5.degree. per foot of travel. However, the prototype was never commercialized.
Several percussion mole steering systems are revealed in the prior art. Coyne et al, U.S. Pat. No. 3,525,405 discloses a steering system which uses a beveled planar anvil that can be continuously rotated or rigidly locked into a given steering orientation through a clutch assembly. Chepurnoi et al, U.S. Pat. No. 3,952,873 discloses an off-axis or eccentric hammer steering system in which the striking position of the hammer is controlled by a transmission and motor assembly. Gagen et al, U.S. Pat. No. 3,794,128 discloses a steering system employing one fixed and one rotatable tail fin.
However, in spite of these and other prior art systems, the practical realization of a technically and cost-effective steering system has been elusive because the prior systems require complex parts and extensive modifications to existing boring tools, or their steering response has been far too slow to avoid obstacles or significantly change the direction of the boring path within the bore hole lengths typically used.
In commonly assigned U.S. Pat. application Ser. No. 720,582, now U.S. Pat. No. 4,632,191, a steering system is disclosed for percussion boring tools for boring in the earth at an angle or in a generally horizontal direction. The steering mechanism comprises a slanted-face nose member attached to the anvil of the tool to produce a turning force on the tool and movable tail fins incorporated into the trailing end of the tool which are adapted to be selectively positioned relative to the body of the tool to negate the turning force. Turning force may also be imparted to the tool by an eccentric hammer which delivers an off-axis impact to the tool anvil.
The fins are constructed to assume a neutral position relative to the housing of the tool when the tool is allowed to turn and to assume a spin inducing position relative to the housing of the tool to cause it to rotate when the tool is to move in a straight direction.
For straight boring, the tail fins are fixed to induce spin of the tool about its longitudinal axis to compensate for the turning effect of the slanted nose member or eccentric hammer. When the fins are in the neutral position, the slanted nose member or the eccentric hammer will deflect the tool in a given direction. The fins also allow the nose piece to be oriented in any given plane for subsequent steering operation.
The apparatus disclosed in our co-pending patent application has the limitation that it is possible for the tool to be disabled in the bore hole and require excavation to recover the drilling mole. There has been some need therefore for a tool which can be operated from a rigid support which permits positive movement of the tool both into and out of the bore hole which would allow the tool to be pulled out by the means used to power it, e.g. an external drilling rig.
The rigid support offers other advantages including (a) providing a conduit to install and/or remove instrumentation, (b) providing a strong member to back-ream or enlarge the hole, (c) providing a tensile member to pull or push utility pipe into the hole, etc.
One object of this invention to provide a cost-effective guided horizontal boring tool which can be used to produce small diameter bore holes into which utiliies, e.g., electric or telephone lines, TV cable, gas distribution piping, or the like, can be installed.
Another object of the invention is to provide a steering system that offers a repeatable and useful steering response in bore holes which is compatible with existing boring equipment and methods and requires only minimal modification of existing boring tools.
Another object of this invention is to provide a steering system which will enable a horizontal boring tool to travel over great distances and reliably hit a small target.
Another object of this invention is to provide boring tool which will produce a guided bore hole to avoid obstacles and to correct for deviations from the planned boring path.
Another object of this invention is to provide a boring tool immune to adverse environmental conditions and which allows the boring operation to be conducted by typical field service crews.
A further object of this invention is to provide a guided horizontal boring tool which requires a minimal amount of excavation for launching and retrieval and thereby reducing the disturbance of trees, shrubs or environmentally sensitive ecosystems.
A further object of this invention is to provide a guided horizontal boring tool which is operated from a rigid external operating member and driven by an external power source.
A still further object of this invention is to provide a guided horizontal boring tool which is supported on a drill rod or pipe and operated by a drill rig either from a launching pit or from the surface.
A still further object of this invention is to provide a guided horizontal boring tool operated from a rigid external operating member and driven by an external power source and controlled for direction of movement from outside the bore hole.
A still further object of this invention is to provide a guided horizontal boring tool operated from a rigid external operating member and driven by an external power source and includes an expander boring element driven into the earth by non-rotative movement.
Other objects of the invention will become apparent from time to time throughout the specification and claims as hereinafter related.
A guided horizontal boring tool constructed in accordance with the present invention will benefit utilities and rate payers by significantly reducing installation and maintenance costs of underground utilities by reducing the use of expensive, open-cut trenching methods. Long utility holes, for gas lines, electrical or communications conduit and the like, may be bored or pierced horizontally through the earth, particularly under obstacles, such as buildings, 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, e.g., by (a) a bent sub for a hammer, (b) a deflection pad on a hammer, (c) an asymmetric hammer or (d) a boring member having an inclined plane on the piercing or boring face.
The drill rod is operated by a drill rig on the surface or recessed in special pit for horizontal drilling and provides for addition of 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 to an extension extending a short distance forward. The tool penetrates the earth upon longitudinal movement of the drill rod.
US Referenced Citations (8)
Continuations (1)
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Number |
Date |
Country |
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863957 |
May 1986 |
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Patent Grant
4858704
