Boring or penetrating the earth – With below-ground tool drive prime mover
Patent
1987-05-01
1988-09-20
Dang, Hoang C.
Boring or penetrating the earth
With below-ground tool drive prime mover
173 64, 173 78, 173 80, 175100, 175215, 175296, 175324, E21B 414
Patent
active
047718358
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
This invention relates to down hole hammers which may be used in drilling holes in any direction.
Throughout the specification reference may be made to particular directional orientations of components and/or movement of components however it should be appreciated that such reference is for the purpose of explanation only and is not intended to be taken as limiting the scope or application of the items being described.
SUMMARY OF THE INVENTION
In one form the invention resides in a down hole hammer comprising a substantially cylindrical casing having a top sub at one end and a drill bit support at the other, a central tube extending through the top sub, casing and a drill bit support to define and enclose annular space between the internal face of the casing the external face of the central tube, an annular piston reciprocately accommodated within the annular space for movement between an impact position at which said piston abutts said drill bit support and a raised position at which said piston is spaced from the drill bit support, fluid porting means being provided to said annular space to effect the reciprocation of the piston between the raised and impact position, the exhaust from the annular space during reciprocation of the piston being exhausted into the central tube, a fluid bypass extending between the top sub and the drill bit support and having an outlet openning into the central tube of the drill bit support and being directed towards the top sub.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention will be more fully understood in the light of the following description of one specific embodiment. The description is made with reference to the accompanying drawings of which
FIG. 1 is a schematic sectional elevation of a down hole hammer according to the embodiment with the piston in the impact position;
FIG. 2 is a schematic sectional elevation of the hammer of FIG. 1 with the piston at an intermediate position;
FIG. 3 is a sectional elevation of the hammer of FIGS. 1 and 2 with the piston in the raised position;
FIG. 4 is a schematic elevation of the hammer of FIGS. 1, 2 and 3 in the "blow down" position; and
FIGS. 5A and 5B are enlarged views of the juction between the casing and drill bit support when the hammer is in the operative position and blow down position respectively.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT OF THE INVENTION
The embodiment is directed towards a down hole hammer comprising a top sub 10 connected to a cylindrical casing 11 which slidably supports a drill bit support 12 (which term includes the drill chuck) at its other end. The lower end of the drill bit support 12 accommodates a drill bit 13 which is shown schematically. The drill bit support accommodates an inner liner 24 which defines a central passageway therein while the drill bit 13 is formed with a central axial passsageway. The casing 11 also supports a central tube 14 which extends from the top sub through the casing and extends past the upper end of the inner liner 24 of the drill bit support to surround the inner end of the drill bit support. The central tube 14 is spaced a small distance from the exterior of the upper end of the inner liner 24 to define a first exhaust 15 for the annular space defined between the internal face of the casing 11 and the central tube 14. The annular space accommodates an annular piston 16 which is slidably received between the casing and the central tube to reciprocate between an impact position as shown at FIG. 1 at which the lower end of the piston impacts against the uppermost end or anvil 17 of the drill bit support as shown in FIG. 1 and a raised position at which the upper end of the piston is adjacent the upper end of the annular space as shown at FIG. 3.
The upper end of the inner liner 24 of the drill bit support extends beyond the drill bit support 12 whereby its external face is sealingly engaged by the piston 16 when the piston is in its impact position (FIG. 1) and for a portion of its upward movement from its impact posi
REFERENCES:
patent: 3198264 (1965-08-01), Oelke et al.
patent: 3225841 (1965-12-01), Thompson
patent: 3795283 (1974-03-01), Oughton
patent: 3924690 (1975-12-01), Shaw
patent: 3941196 (1976-03-01), Curington et al.
patent: 4321974 (1982-03-01), Klemm
patent: 4509606 (1985-04-01), Willis
Dang Hoang C.
Wallis Drilling Pty. Ltd.
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