Boring or penetrating the earth – With tool shaft detail
Reexamination Certificate
1999-07-06
2001-06-05
Pezzuto, Robert E. (Department: 3671)
Boring or penetrating the earth
With tool shaft detail
C175S389000
Reexamination Certificate
active
06241033
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to drilling. More particularly, the invention relates to a method of extending the length of a drill string. It also relates to a drill string element and to a coupling member. It further relates to a shank rod and to a drill string.
In top hammer drilling, use is made of a hammer which rotates and applies an axial percussive load to a drill string in order to drill holes in the ground.
The drill string comprises a first member mounted in the hammer to which one or more extension rods are connected end-to-end. A drill bit is provided at the leading end of the drill string.
The first member, herein called a “shank rod”, typically includes an elongate shank having a leading end and a trailing end. An annular collar is provided on the shank rod intermediate the leading end and the trailing end. At least part of the shank rod between the trailing end and the collar is non-circular in cross-section such that when a trailing end portion of the shank rod is positioned in the hammer, the hammer can engage the non-circular portion to rotate the drill string and apply axial percussive loads to the trailing end of the shank rod. The leading end of the shank rod is configured to be connected to a trailing end of the rearmost (uppermost) extension rod of the drill string.
As drilling proceeds and the drill string penetrates deeper into the ground it becomes necessary periodically to extend the length of the drill string. This is achieved by disconnecting the leading end of the shank rod from the trailing end of the rearmost (uppermost) extension rod, and connecting a leading end of a new extension rod to the trailing end of the rearmost extension rod and connecting a trailing end of the new extension rod to the leading end of the shank rod.
One disadvantage with this procedure is that it is relatively time consuming. A further disadvantage is that in certain applications, e.g., in stope drilling, space is restricted, which can make it extremely difficult to connect a new extension rod in position between the shank rod and the rearmost extension rod.
It is an object of this invention to alleviate these problems.
SUMMARY OF THE INVENTION
According to one aspect of the invention there is provided a method of extending the length of a drill string which includes a shank rod, a trailing end portion of which is positioned in a hammer, the method including the steps of:
disconnecting the shank rod from the hammer;
mounting a subsequent shank rod in the hammer; and
connecting a leading end of said subsequent shank rod to a trailing end of the previous shank rod.
It is to be appreciated that the shank rod being disconnected from the hammer remains attached to the drill bit or remainder of the drill string and hence forms an element of the drill string,
This procedure can be repeated as often as desired with, each time, a leading end of a subsequent shank rod being connected to a trailing end of a previous shank rod.
In this way, the drill string is extended making use of drill string elements which functioned initially as shank rods and subsequently as extension rods.
In one embodiment of the invention, connecting a leading end of the subsequent shank rod to the trailing end of the previous shank rod may include positioning a connecting member integral with the subsequent shank rod at the leading end thereof in driving engagement with the trailing end of the previous shank rod.
In another embodiment of the invention, connecting a leading end of the subsequent shank rod drivingly to the trailing end of the previous shank rod may be by means of a coupling member which is interposed between the shank rods.
According to another aspect of the invention there is provided a drill string element which includes:
an elongate shank having a leading end and a trailing end;
a collar provided on the shank intermediate the leading end and the trailing end, at least part of the shank between the trailing end and the collar being receivable in a hammer and being of non-circular cross-section for at least part of its length; and
connecting formations at the leading end and trailing end of the shank whereby the drill string element is connectable end-to-end to a similar drill string element.
In one embodiment of the invention, the connecting formations may be configured such that the connecting formation at the leading end of the shank of one drill string element is connectable to the connecting formation at the trailing end of the shank of another drill string element by means of a coupling member having complementary connecting formations which is interposed between the drill string elements.
The connecting formations may be in the form of tapered end portions.
At least one of the tapered end portions may be noncircular in cross-section for at least part of its length.
In another embodiment of the invention, the connecting formations may be complementary in shape such that the connecting formation at the leading end of the shank is releasably and drivingly connectable to the complementary connecting formation at the trailing end of the shank of a similar drill string element.
The one connecting formation may be in the form of a tapered end portion and the other connecting formation being in the form of a complementary socket.
The tapered end port-Ion is typically provided at the trailing end of the shank, and the complementary socket is provided at the leading end of the shank.
The tapered end portion and socket may be of complementary non-circular cross-section for at least part of their lengths.
According to another aspect of the invention there is provided a coupling member for drivingly connecting together a pair of drill string elements as described above, which defines a pair of oppositely disposed tapering sockets interconnected by a flushing passage, at least one of the tapering sockets being of non-circular cross-section for at least part of its length.
Each socket may have at least one flat surface.
According to still another aspect of the invention there is provided a shank rod suitable for use in the above method, which rod has at a trailing end thereof connecting means whereby it is connectable to a leading end of another similar shank rod.
The connecting means may include a taper at the trailing end of the shank rod.
In one embodiment of the invention, the leading end of the shank rod may define a complementary tapered socket within which a tapered trailing end of another similar shank rod is taper lockingly receivable.
In another embodiment of the invention, the leading end of the shank rod may be tapered. Hence, a leading end of a shank rod of this type will be connectable to a trailing end of a similar shank rod by means of a coupling member having a pair of oppositely disposed complementary tapered sockets within which the leading end of one shank rod and the trailing end of the other shank rod are taper lockingly receivable.
The or each tapered end portion of the shank rod may be non-circular in cross-section for at least part of its length.
According to still another aspect of the invention there is provided a drill string which includes at least one of a shank rod, drill string element and coupling member of the type described above.
REFERENCES:
patent: 4094364 (1978-06-01), Lundstrom et al.
patent: 4852672 (1989-08-01), Behrens
patent: 6102141 (2000-08-01), Engstrom et al.
Burns Doane Swecker & Mathis L.L.P.
Pezzuto Robert E.
Sandvik AB
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