A retaining arrangement suitable for use with a drill string assembly having a sub adaptor and a drill spindle in use connected together, the retaining arrangement including: one or more retaining bodies, the or each retaining body comprising a connection region for removably connecting the or each retaining body to one of the sub adaptor and the drill spindle; and a first retaining or catch region adapted to catch the other of the sub adaptor and drill spindle.

FIELD OF THE INVENTION

The present invention relates generally to connecting and retaining devices, in particular applications, being connectors for use in drilling operations.

BACKGROUND OF THE INVENTION

In drilling operations, it is common to use sacrificial or consumable parts in high wear areas. One such area is the drill string assembly. The drill string assembly usually comprises a lesser expensive consumable known as a sub adaptor, which connects the typically more expensive drill spindle to other drill string elements such as a drill bit or drill extension stem. The drill spindle must, in use, operate in forward and reverse, without the sub adaptor uncoupling from the drill spindle.

There have been many ways of locking the sub adaptor to the drill spindle, including: welding tabs between the sub adaptor and spindle. However, these methods often involve damaging the more expensive drill spindle, potential electric shock to welding operators, the need for skilled labour, thread leakage while drilling, and other disadvantages.

The present invention seeks to alleviate one or more of the above mentioned disadvantages.

SUMMARY OF THE INVENTION

According to one aspect of the present invention there is provided a retaining arrangement suitable for use with a drill string assembly having a sub adaptor and a drill spindle in use connected together, the retaining arrangement including: one or more retaining bodies, the or each retaining body comprising a connection region for removably connecting the or each retaining body to one of the sub adaptor and the drill spindle; and a first retaining or catch region adapted to catch the other of the sub adaptor and drill spindle.

According to one form, the connection region is removably connected to one of the sub adaptor and the drill spindle by one or more fasteners. In one form, the connection region includes one or more openings adapted to receive the one or more fasteners.

In a further form, the fasteners are screw thread fasteners and are removably connected to the sub adaptor or drill spindle by a corresponding screw thread arrangement located on the one of the sub adaptor and drill spindle.

In another form, the connection region is arranged around a periphery of the retaining body.

According to one form the or each retaining body is a shell or curved plate. In another form, the or each retaining body is a hollow part-cylinder.

According to one form, the first retaining region includes a catch element and in a further form the catch element is a peripheral flange or rib. In another form, the catch element includes a return or a dove tail.

According to another form, a second retaining region is provided, adjacent the connection region. In one form, the connection region is adjacent a first end of the retaining body and the first retaining region is disposed at a distal or second end. In a further form the second retaining region is in the form of a flange which extends inwardly from an inner periphery of the retaining body, so as in use to engage with a corresponding external feature of the drill spindle or sub adaptor.

According to another form the retaining arrangement further includes a seal element disposed in a central cavity within the drill spindle and sub adaptor. In one form, the seal element is in the form of a tube with one end fastened to one of the sub adaptor and drill spindle and the other end engaged with the other of the sub adaptor and drill spindle. In one form, the one end of the seal element is fastened to one of the sub adaptor and drill spindle by means of an interference fit. In a further form, the other end of the seal element engages with the other of the sub adaptor and drill spindle by frictional engagement by means of an O ring located around the periphery of the other end of the seal element.

According to another aspect the present invention provides a sub adaptor, or consumable, which is adapted to removably mount a retaining device for inhibiting separation of the sub adaptor from a drill spindle when in use.

According to a further aspect the present invention provides a drill spindle which is adapted to removably mount a retaining device for inhibiting separation of a sub adaptor from the drill spindle.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT

Referring to the drawings there is shown a coupling arrangement generally indicated at10, the coupling arrangement10being suitable for use with a drilling sub adaptor generally indicated at12.

The drilling sub adaptor12is adapted to receive a drill consumable. The sub adaptor12in use engages with a drill spindle14by thread19.

In order to inhibit the sub adaptor12being disengaged from the spindle14, a retaining arrangement20is provided. The retaining arrangement20includes a first retaining body22and a second retaining body24. The retaining bodies22,24are in the form of curved plates, or shells, and are in the embodiment shown, identical half-annular cylinders for improved retention and strength and inter-locking, and one will be described herein, but it is to be understood that the other one incorporates the same features as the first.

The retaining body24includes a connection region26adapted to removably connect the retaining body24to the sub adaptor12, but it could equally well connect the retainer body to the spindle14.

The connection region26is disposed adjacent a first end of the retaining body24and includes a plurality of fastening apertures27for receiving threaded fasteners (not shown) there through. The apertures27are countersunk for a flush finish with the external periphery of the drilling sub adaptor12. The apertures27may be spaced around the circumference or periphery of the retainer body22,24so as to facilitate improved retaining.

The retainer body22,24further includes a first retaining or catch region25adapted to catch a corresponding catch region32of the drill spindle14. The first retaining or catch region30is disposed distal the connection region26, at the second or distal end of the retaining body22,24. The first catch region25includes a catch33, comprising a peripheral flange, rib or return or dovetail which in use engages with a similarly-shaped rib or return34disposed on the drill spindle14. The arrangement is such that when connected, the retainer catch25positively engages with the spindle14.

A second retaining or catch region36is disposed on the retainer body22,24, adjacent the connecting region26. The second retaining region36is like the first25, and retains the sub adaptor12should the fasteners (not shown) fail.

A seal arrangement is provided, generally indicated at40. The seal40includes a seal element in the form of a seal tube44, which is disposed inside the drill spindle14and sub adaptor12when in use. The seal tube44incorporates an O-ring mounting45and when assembled, the O-ring46itself. It is to be appreciated that the central passage47is a conduit for high pressure water and air and thus the arrangement shown is advantageous in reducing leakage of that water through the sub adaptor/spindle-thread connection. That is, the seal tube44mounts on a shoulder (not shown) in an interference fit which is downstream of an upstream end of the drill spindle14. At the upstream end of the seal tube44is the O-ring46to inhibit water leaks at that end.

The retaining shells22,24further inhibit water leakage, due to their being a barrier held against the periphery of the sub adaptor, but also due to their retaining function—they inhibit uncoupling or even unscrewing of the sub adaptor, so the O-ring and seal tube are kept between shoulders (not shown) for improved sealing.

The retaining shells22,24are disposed at an outer periphery of the drilling sub adaptor assembly12and when in place have an outer surface generally flush with the other outer surfaces of the sub adaptor12. This is advantageous because the adjoining seals and seal plates may be replaced when the retaining shells22,24are removed.

Those skilled in the art will appreciate that the present invention may be susceptible to variations and modifications other than those specifically described. It is to be understood that the present invention encompasses all such variations and modifications that fall within its spirit and scope.