(57) The invention provides a drill pipe rotary drive mechanism for an earth drilling
apparatus comprising a housing, a drive member mounted in the housing for rotation
therein about a rotary axis and having an axial bore opening at each end to the exterior
of the housing, and a drive mechanism in the housing for rotatably driving the drive
member. A drive coupling tool is adapted to be readily removably mounted in the drive
member so that the drive mechanism can be used for rotatably driving different types
of earth drilling tools, the coupling tool having a tubular body portion telescopingly
removably mounted in the axial bore of the drive member, the body portion having an
axial opening extending therethrough for reception of a portion of the length of the
drill pipe, a flange at one end of the body portion for abutting engagement with one
end of the drive member for axially locating the coupling tool in the drive member,
the coupling tool being adapted to be non-rotatably coupled to a drilling tool and
to the drive member.
The invention also provides a dual-wall drill pipe section comprising an outer pipe
member having a box end formed with an internal thread and a pin end formed with an
external thread for engagement with the box end of another outer pipe member, the
bore of one of the ends of the outer pipe member is formed with a shoulder and a circumferential,
inwardly facing groove axially spaced from the shoulder, an inner pipe member concentrically
disposed within the outer pipe member so as to define an annular passage between the
inner and outer pipe members, spacer members connected to each end of the inner pipe
member and disposed in the annular passage for maintaining concentricity between the
inner and outer pipe members, the spacer members at one end of the inner pipe being
formed with a shoulder for abutting engagement with the shoulder of the outer pipe
member so as to axially locate and support the inner pipe member within the outer
pipe member, and at least one spring member connected to the inner pipe member and
having a portion engageable with the groove of the outer pipe member for resiliently
and frictionally retaining the inner pipe member within the outer pipe member during
drilling, storage and handling of an assembled pipe section.
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