CROSS-REFERENCE TO RELATED APPLICATION(S)

The present application derives priority from U.S. provisional patent application serial no. 62/318,252 filed 5 April 2016.

BACKGROUND OF THE INVENTION

1. Field of the invention

The present invention relates to drill rods for ground (soil and rock) drilling equipment, and more particularly, to drill rods comprising a number of members extendable in the manner of a telescope. The rods can be used with non-telescoping rods or with additional telescoping rods to allow ground drilling connecting a drilling rig to a drilling bit to allow for drill hole advancement.

2. Description of the Background

Mobile drill rigs are typically used for earth drilling in various geologic drilling applications. The mobile drill rig typically includes a drill mast mounted onto a truck chassis. A rotatable drill head is slideably mounted on the drill mast and can be driven up or down along the length of the erected drill mast. The drill head screws a drill string into the ground, gripping and turning the uppermost section of drill pipe of the string.

Drill pipe, is hollow, thin-walled, steel piping and comes in a variety of sizes, strengths, and weights but are typically within a range of from 5 to 40 feet in length. They are hollow to allow drilling fluid to be pumped through them, down the hole, and back up.

In practice, the drill string is extended by drilling in each drill rod

sequentially and by attaching the next rod to the trailing end of the drill string, and repeating. This changeover is difficult, time consuming and sometimes dangerous. It would be highly desirable to provide a drill rod that can be used for drilling a bore and aiso limit the number of assembly iterations required to advace the driii hole The present invention does this with a telescopically extendable drill rod that may be extended during the actual drilling operation thereby avoiding any need to assemble further sections to the drill rod in order to extend it. The present invention also allows the use of a shorter drill mast, which in turn requires fewer tooling additions and smaller and more economical equipment. AIso,the shorter drill masts facilitates drilling in limited access conditions that would preclude the use of large equipment with longer drill masts.

One skilled in the art will understand that Kelly drilling employs

"telescopically extendable" drill attachments in a loose sense. Kelly drilling is often used for oil drilling and for the production of foundation piles for buildings, in this case, the rotary drive of the drill turns a Kelly rod arrangement, which comprises several nested tubular Kelly rods of square cross-section. The rotational movement of one rod is transmitted to the adjacent Kelly rod. Kelly rod attachments can be added down the hole. Kelly drilling is good for larger holes and rocky formations but is not well-suited for "tieback" (micropile) drill rigs and other small hole drilling rigs. A tieback is a horizontal wire, rod, or helical anchor used to reinforce retaining walls for stability. With one end of the tieback secured to the wall, the other end is anchored to a micropile anchored in the earth. The tieback-pile structure resists forces that would otherwise cause the wall to lean. What is needed is a telescopically extendable drill rod more suitable for use with tieback drill rigs (alternately known as micropile drill rigs) suitable for use in a wide range of small-hole drilling applications including anchor drilling, mieropiles, soil nailing, water wells and jet grouting, and other such smaller hole drilling. SUMMARY OF THE INVENTION

An object of the invention is to provide a telescopic drill rod which is of the simplest possible construction but which is nevertheless able to transmit drilling pressure when in the extended position. A further object of the invention is to enable the individual members of the rod, while in the extended position, to be easily connected together and also easily disconnected using standard rotary tieback drilling equipment for installations substantially similar to those as described above.

The invention comprises a telescopic drill rod comprising at least two rod members disposed coaxially to one another, including an inner rod member and an outer rod member axially slidable relative to each other in a telescoping manner between an extended position and a retracted position. Both the inner rod member and outer rod member are equipped with joints at each end for connection to a drill head and/or another section of drill pipe. The joints also lock the inner and outer rod members in either the extended or retracted positions, and this is accomplished with a unique frusto-conical threaded engagement that is well-suited for transmitting pressure forces.

The invention makes it possible for the members of a telescopic drill rod to be coupled together in the extended position, without further aids or additional devices, in a simple, convenient manner which is particularly suitable for practical operation, in such a manner that rotational and axial drilling forces with or without drilling fluid use can be applied.

For a more complete understanding of the invention, its objects and advantages, refer to the remaining specification and to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

Other objects, features, and advantages of the present invention wiii become more apparent from the following detailed description of the preferred embodiment and certain modifications thereof, in which:

FIG. 1 is a side cross-section of a telescopic drill rod 2 in its unsecured intermediate position according to an embodiment of the invention with enlarged insets of some components.

FIG. 2 shows the telescopic drill rod 2 secured in its fully-retracted position.

FIG. 3 shows the telescopic drill rod 2 secured in its fully-extended position DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention is a telescopic drill rod comprising two or more rod members: at least including an inner rod member and an outer rod member axially slidabie relative to each other in a telescoping configuration between an extended

position and a retracted position.

FIG. 1 is a side cross-section of a telescopic drill rod 2 according to an

embodiment of the invention shown in an intermediate (unsecured) position. The

telescopic drill rod generally comprises the inner rod member 30 and outer rod

member 20, inner rod member 30 being slidably carried in telescoping manner within the outer rod member 20. The inner rod member 30 can be secured in a fully retracted position (shown and described below with reference to FIG. 2), unsecured as shown in FIG. 1 for free telescoping extension or retraction, or fully extended and secured in the fully extended position (shown and described below with reference to FIG. 3).

The inner rod member 30 further comprises an elongate hollow pipe section

32 of uniform or variable cross-section Dl extending from one end to an enlarged double-male joint 34 at the other end. Section 32 preferably has a uniform cross- section aiong its length symmetric about a central axis, and subject to that constraint may be cylindrical, hexagonal, octagonal oir otherwise. As seen in the enlarged center inset to FIG. 1 double-male joint 34 comprises a bulbous distal tip shaped with two threaded surfaces 33A, 33B separated by a raised medial collar 33 of diameter D2. In the preferred embodiment both threaded surfaces 33 A, 33B are oppositely tapered as shown, in which case the two threaded surfaces 33A, 33B comprise frusto-conical shapes tapering away from collar 33 with surfaces screw-threaded along their lengths. The frusto-conical shape provides a wedging effect. However, one skilled in the art will understand that non-tapered threads are suitable, in which case the case the two threaded surfaces 33A, 33B are of uniform cross-section comprising cylindrical shapes tapering away froru collar 33 with surfaces screw-threaded along .-their lengths: of slightly greater diameter D2 than the largest threads of surfaces 33 A, 33B and presents a smooth fiat surface to serve as a bushing for slidable engagement with the inner surface of outer rod member 20. The smallest threads of surfaces 33A, 33B are of slightly greater width/diameter D 1 than the hollow pipe section 32

The inner rod member 30 extends to another single-female joint 36 mounted on the other end. Single female joint 36 comprises a thicker cylindrical section of uniform exterior dimension formed with a cylindrical receptacle 39 on one end of diameter slightly larger than D2 for a compression and/or screw-threaded fit with cylindrical section 32. The outer face of single-female joint 36 is formed with a screw-threaded receptacle (again, tapered-conical or non-tapered threads) opening outward to an aperture. The receptacle of single- female joint 36 is shaped, dimensioned and threaded for screw-insertion of a conventional drill head (not shown) or, alternatively, for screw-insertion of another inner rod member 30. The outer rod member 20 comprises an elongate hollow cylinder 22 of inner diameter D3 slightly greater than D2 of coiiar 33 for slidabie insertion of the doubie- male joint 34 of inner rod member 30. The leftmost end of the outer rod member 20 is equipped with a single-female joint 24 compression and/or screw-threaded into the end of cylinder 22. Single-female joint 24 is a thicker cylindrical section having a two-tier exterior dimension for flush insertion into the cylinder 22. The inner face of single-female joint 24 is formed with a threaded receptacle (again, tapered-conical or non-tapered threads) opening inward from an aperture to a through-bore of diameter Dl. Where tapered threads are used, the receptacle of the inner face of single-female joint 24 is frusto-conical, and the frusto-comcal receptacle of single-female joint 24 is shaped, dimensioned and threaded to conform to the innermost frusto-conical threaded surface 33A of the double-male joint 34 of inner rod member 30 for screw - insertion therein. However, one skilled in the art will understand that non-tapered threads are suitable, in which Case the Case the threaded surface of the receptacle of the inner face of single-female joint 24 is of substantially uniform cross-section with non-tapered threads. The through-bore through single-female joint 24 continues outward through the outer face of single-female joint 24, and the through-bore may or may not be internally grooved for holding a rubberized rod wiper 25, e.g., an O-ring or other such wiping device or mechanism, captive therein where wiping might be of advantage to the drilling. The rod wiper 25 squeegees the inner rod member 30 clean as is slides through.

The other end (rightward) of the outer rod member 20 is equipped with a double-female joint 26 that is compression and/or screw-threaded into the end of cylinder 22, Double-female joint 26 is a thicker cylindrical section having a two-tier exterior dimension for flush insertion into the cylinder 22. The inner (leftmost) face of double-female joint 26 is formed with an inner cylindrical lip 27 having a diameter slightly more than D2, lip 27 opening inward to a threaded receptacle 29 shaped, dimensioned and threaded to conform to the outermost threaded surface 33B of the double-male joint 34 of inner rod member 30 for screw-insertion therein. Once more, tapered -conical or non-tapered threads may be used. Where tapered threads are used as shown, the receptacle 29 of double-female joint 26 is frusto-conical, and the frusto- conical receptacle 29 of double-female joint 26 is shaped, dimensioned and threaded to conform to the outermost frusto-conical threaded surface 33B of the double-male joint 34 of inner rod member 30 for screw-insertion therein. However, one skilled in the art will understand that non-tapered threads are suitable, in which case the case the threaded surface of the receptacle of the receptacle of double-female joint 26 is of uniform cross-section. The outer (rightmost) face of double-female joint 26 is likewise formed with a non-tapered (uniform) or tapered (frusto-conical) threaded receptacle 23. A tapered threaded receptacle 23 is illustrated in FIG. 1 with a diameter tapering outward to an aperture of slightly more than D2.

The length of outer rod member 20 is L1 , and inner rod member 30 is L2, giving a sum component length of L1 + L2. However, it should now be apparent that the invention makes it possible for the inner and outer members 30, 20 of the telescopic drill rod 2 may be securely coupled together in the retracted and/or extended position by screw-insertion, without aid from further devices, in a simple, convenient manner. The present configuration optimizes both extension and retraction without compromising strength and security when locked in either the fully extended or fully retracted position.

FIG. 2 shows the telescopic drill rod 2 in its fully-retracted position with the double-male joint 34 of inner rod member 30 screw-inserted into the leftmost receptacle of the double female joint 26 of outer rod member 20. In this position the total length L3 is greater than Li by about the length of singie-femaie receptacle 36.

FIG. 3 shows the telescopic drill rod 2 in its fully-extended position with the double-male joint 34 of inner rod member 30 screw-inserted into the female receptacle of the single female joint 24 of outer rod member 20. In this position L3 is slightly less than L 1 + L2 by a bit more than the length of double-male joint 34.

Having now fully set forth the preferred embodiments and certain

modifications of the concept underlying the present invention, various other embodiments as well as certain variations and modifications of the embodiments herein shown and described will obviously occur to those skilled in the art upon becoming familiar with said underlying concept. It is to be understood, therefore, that the invention may be practiced otherwise than as specifically set forth in the appended claims.

STATEMENT OF INDUSTRIAL APPLICABILITY

Large hole drilling applications sometimes use "Keiiy driiis" that employ telescopically extendable drill attachments, allowing Kelly rod attachments to be added down the hole. However, there are numerous construction applications that require small-hole drilling including anchor drilling, micropiles, soil nailing, water wells and jet grouting, and other such smaller hole drilling. While conventional Kelly drilling is good for larger holes and rocky formations it is not well-suited for "tieback" (micropile) drill rigs and other small hole drilling rigs. There would be great industrial applicability in a telescopically extendable drill rod more suitable for use with tieback drill rigs (alternately known as micropile drill rigs) suitable for use in small-hole drilling.