FIELD OF INVENTION

This invention relates to a connector assembly for use with a drilling apparatus.

BACKGROUND TO INVENTION

A connector assembly as herein envisaged is disposed between the output of the drill motor of a drilling apparatus, as used for drilling holes in open cast mines, and the like, and a drill pipe of the apparatus having a drill bit at a lower end thereof. The drill pipe itself is made up of a string of drill pipe segments including a drilling segment incorporating the drill bit and extension segments that are located, one after another, in line with the drilling segment, to provide for a hole to be drilled to a required depth. The drill pipe segments and the output of the drill motor conventionally define complementary thread formations whereby they are releasably connected in line with one another, the segments generally defining a passage therethrough through which a cooling fluid under pressure, such as compressed air or liquid, can be conveyed to the working end of the drill pipe, for cooling purposes during drilling and/or for displacing dust particles formed as a result of drilling, commonly referred to as chippings, from a hole being drilled. The cooling fluid exits via holes in the drill bit and travels up an annular space defined between the drill pipe and the wall of a hole being drilled by the drill bit. In this manner, chippings are conveyed by the cooling fluid upwardly and out of the hole.

It is known in relation to the use of drilling apparatus of the above type that as drilling progresses, further extension segments are connected, one after another, in line with the drill pipe, whereas the withdrawal of the drill pipe from a hole drilled requires the reverse to occur, i.e. extension segments are removed, one after another, from the drill pipe. The drilling of holes, therefore, is a stop/start operation and for this reason and also generally due to the nature of drilling holes in mining environments, rotational and axial shocks are transmitted through a drill pipe to the drill motor of the drilling apparatus. As such, and in order to avoid damage to the drill motor as a result of, in particular, rotational shocks, a connector assembly, that serves as a shock absorbing assembly, acts between the drill pipe and the output of the drill motor, the present invention relating specifically to such a connector assembly.

A known connector assembly providing for shock absorption, is disclosed in the applicant’s South African Patent Application ZA2013/08143 includes an input connector unit connectable to the output of a drill motor of a drilling apparatus and an output connector unit connectable to a drill pipe string. The input connector unit includes a number of circumferentially spaced downwardly extending drive bodies and the output connector unit includes a number of circumferentially spaced upwardly extending driven bodies. The driven bodies are located in spaces defined between the drive bodies in an arrangement wherein torque exerted by the drill motor is transmitted to the drill string via rotational engagement of the drive bodies with the driven bodies. A chamber defined between the input and output connector units, is filled with a settable resiliently deformable material providing for absorption of shock forces between the input and output connector units during a drilling operation. The input and output connector units have threaded spigot and socket connector formations respectively, for connection with the drill motor and a drill pipe of a drill string, respectively.

A problem encountered with known connector assemblies, including the applicant’s connector assembly disclosed in ZA2013/08143, is that connection of the drill string to the output connector unit often results in damage to threaded connector formations of the output connector unit and the drill string due to impact forces when the threaded connector formation of the output connector unit of the connector assembly is connected to the threaded connector formation of the drill string. Typically, the damage occurs when an operator lowers the connector assembly onto the uppermost drill pipe of the drill string, too quickly. The impact forces are known to cause damage to the threads of the connector formations of the relevant drill pipe of the drill string and the output connector unit of the connector assembly, often resulting in a need to repair or replace damaged components and consequently downtime of the drilling apparatus.

It is an object of the present invention to provide a connector assembly which ameliorates the abovementioned problems experienced with known connector assemblies.

SUMMARY OF INVENTION

According to the invention there is provided a connector assembly for use with a drilling apparatus for connecting a drill motor of the drilling apparatus to a drill pipe, the connector assembly including: a top drive unit including: a) an upper carrier structure and an input shaft which is fixedly connected to the upper carrier structure, the upper carrier structure including at least one drive formation, the input shaft having an open upper end and an open lower end and an internal passageway extending between the upper and lower ends, the upper end of the input shaft having a connector formation which is connectable to a power output of the drill motor of the drilling apparatus; b) a lower carrier structure which includes at least one driven formation which is arranged for engagement by the drive formation of the upper carrier structure for transmitting torque applied to the upper carrier structure by the drill motor to the lower carrier structure; an open-ended central conduit segment which is fixedly connected to the lower carrier structure and which defines an internal passageway which is aligned with the internal passageway of the input shaft of the upper carrier structure; and a lower drive assembly comprising a number of circumferentially-spaced, downwardly-extending drive rods which are fixedly connected to the lower carrier structure; and c) a resiliently deformable shock-absorbing formation which is located between the drive formation and the driven formation of the upper and lower carrier structures, respectively, for absorbing impact forces acting between the drive formation and the driven formation during a drilling operation, a lower floating connector unit for connection with a threaded connector formation of a drill pipe, the lower floating connector unit including a driven member defining a number of guide apertures within the drive rods of the lower drive assembly of the top drive unit, are slidably received in an arrangement wherein torque applied to the lower drive assembly is transmitted to the driven member, while allowing for sliding displacement of the drive rods within the guide apertures of the driven member, the driven member including an output shaft having a threaded connector formation for threaded engagement with the connector formation of the drill pipe, the output shaft defining an internal passageway which is aligned with the internal passageway of the central conduit segment of the lower carrier structure, sliding displacement of the drive rods within the guide apertures of the driven member providing for attenuation of impact forces when connecting the connector assembly to the drill pipe. The upper carrier structure of the top drive unit may include an upper carrier plate defining a central aperture within which the input shaft is fixedly located.

The at least one drive formation of the upper carrier structure may comprise a number of circumferentially-spaced drive bodies which extend downwardly from the upper carrier plate.

The connector formation of the input shaft may comprise an externally-threaded spigot for screw-threaded engagement with a complementary internally-threaded socket of the power output of the drill motor.

The lower carrier structure may include a lower carrier plate defining a central aperture within which the central conduit segment is fixedly located.

The at least one driven formation of the lower carrier structure may comprise a number of circumferentially-spaced driven bodies which extend upwardly from the lower carrier plate, the driven bodies being located in spaces defined between the drive bodies of the upper carrier structure in an arrangement wherein torque applied to the upper carrier structure by the drill motor is transmitted to the lower carrier structure via rotational engagement of the driven bodies by the drive bodies.

The top drive unit may include a top cover extending between the upper carrier plate and the lower carrier plate, the upper and lower carrier plates and the top cover defining an internal chamber within which the drive bodies and the driven bodies are housed.

The shock absorbing formation may be in the form of a shock absorbing body which is formed within the internal chamber by filling the internal chamber with a settable shock absorbing material while in a flowable form and allowing the shock absorbing material to set and cure within the internal chamber, the shock absorbing body acting between the drive bodies and the driven bodies for absorbing rotational shocks acting between the drive bodies and the driven bodies during use of the drilling apparatus.

The connector formation of the output shaft of the lower floating connector assembly may comprise an internally threaded socket for screw-threaded engagement with a complementary externally-threaded spigot of the drill pipe.

The driven member may comprise a flange plate defining the guide apertures. The flange plate may define a central aperture within which the output shaft is fixedly located. An upper end of the output shaft may be slidably displaceable relative to a lower end region of the central conduit segment of the lower carrier structure. More specifically, the lower end region of the central conduit segment may be slidably received within the internal passageway at an upper region of the output shaft.

The lower floating connector unit may include a lower cover surrounding the output shaft and extending upwardly to the lower carrier plate of the upper carrier structure for housing a lower end region of the central conduit segment and the drive rods.

BRIEF DESCRIPTION OF THE DRAWINGS

Further features of the invention are described hereinafter by way of a non-limiting example of the invention with reference to, and as illustrated in the accompanying diagrammatic drawings. In the drawings:

Figure 1 shows a three-dimensional view of a first embodiment of a connector assembly in accordance with the invention;

Figure 2 shows a sectional three-dimensional view of the connector assembly of Figure 1 ; Figure 3 shows an exploded three-dimensional view of the connector assembly of Figure 1 ;

Figure 4 shows an exploded sectional side view of the connector assembly of Figure 1 ;

Figure 5 shows a sectional side view of the connector assembly of Figure 1 , in a first mode of operation of the connector assembly, wherein the lower floating connector is in a raised position;

Figure 6 shows a sectional side view of the connector assembly of Figure 1 , in a second mode of operation of the connector assembly, wherein the lower floating connector unit is in a lowered position;

Figure 7 shows a sectional plan view of the connector assembly of Figure 1 , sectioned along section line VII-VII of Figure 1 ;

Figure 8 shows a sectional plan view of the connector assembly of Figure 1 , sectioned along section line VIII-VIII of Figure 1 ;

Figures 9A-9C show sectional side views of the connector assembly of Figure 1 and a fragmentary upper end region of a drill pipe of a drill string, illustrating, in sequence, the manner in which the drill pipe is connected to the connector assembly and showing the modes of operation of the lower floating connector unit;

Figure 10 shows an exploded three-dimensional view of a second embodiment of a connector assembly in accordance with the invention;

Figure 11 shows an exploded sectional side view of the connector assembly of Figure 10; Figure 12 shows a sectional side view of the connector assembly of Figure 10, in a first mode of operation of the connector assembly, wherein the lower floating connector is in a raised position; and

Figure 13 shows a sectional plan view of the connector assembly of Figure 10, sectioned along section line XIII - XIII of Figure 12.

DETAILED DESCRIPTION OF THE INVENTION

With reference to Figures 1 - 9 of the drawings, a first embodiment of a connector assembly in accordance with the invention, for use with a drilling apparatus used for drilling holes in a rock substrate, for connecting a drill motor of the drilling apparatus to a drill pipe of a drill string, is designated generally by the reference numeral 10.

The connector assembly 10 comprises, broadly, a top drive unit 12 and a lower floating connector unit 14.

The top drive unit 12 is of a steel construction and includes an upper carrier structure including an upper carrier plate 16 having a central aperture 18 and an input shaft 20 which is located within the central aperture of the upper carrier plate and welded thereto.

The upper carrier structure includes four circumferentially-spaced drive bodies 22 which extend downwardly from the upper carrier plate 16.

The input shaft 20 has an open upper end 24 and an open lower end 26 and an internal passageway 28 extending between the upper and lower ends. An upper end region of the input shaft 20 which projects above the upper carrier plate 16 has a connector formation in the form of an externally-threaded spigot 30 for screw-threaded engagement with a complementary internally-threaded socket of a power output shaft of the drill motor of the drilling apparatus.

The top drive unit 12 further includes a lower carrier structure including a lower carrier plate 32 which defines a central aperture 34 and four circumferentially-spaced holes 35. The lower carrier structure includes four circumferentially-spaced driven bodies 36 which extend upwardly from the lower carrier plate and which are located in spaces defined between the drive bodies 22 of the upper carrier structure in an arrangement wherein torque applied to the upper carrier structure by the drill motor is transmitted to the lower carrier structure via rotational engagement of the driven bodies by the drive bodies.

The lower carrier structure includes an open-ended central conduit segment 38 which is located within the central aperture 34 of the lower carrier plate 32 and welded thereto. The central conduit segment 38 defines an internal passageway 40 which is aligned with the internal passageway 28 of the input shaft of the upper carrier structure. The lower carrier structure further includes a lower drive assembly comprising four circumferentially-spaced downwardly-extending drive rods 42 which are located in the holes 35 provided therefor in the lower carrier plate 32 and welded thereto.

An O-ring seal 44 and a sealing sleeve 46 are located between the input shaft 20 and the central conduit segment 38 providing a fluid-tight sealing system between the input shaft and the central conduit segment.

The top drive unit 12 incudes an outer cylindrical cover 48 which extends between and is welded to the upper carrier plate 16 and the lower carrier plate 32. The upper and lower carrier plates and the cover define an internal chamber 50 within which the drive bodies 22 and the driven bodies 36 are housed. A lock ring 49 is provided which locks the upper carrier plate 16 in position. The top drive unit 12 includes a resiliently deformable shock absorbing formation in the form of a shock absorbing body which is formed within the internal chamber 50 by filling the internal chamber with a settable shock absorbing material while in a flowable form and allowing the shock absorbing material to set and cure within the internal chamber, the shock absorbing body acting between the drive bodies and driven bodies for absorbing rotational and axial shocks acting between the drive bodies and the driven bodies during use of the drilling apparatus.

The lower floating connector unit 14 is of a steel construction and is configured for connection with an externally-threaded spigot 60 of a drill pipe 62 of a drill string. The lower floating connector unit 14 includes a driven member in the form of a flange plate 64 defining four guide apertures in the form of round guide holes 66 within which the drive rods 42 of the top drive unit, are slidably received in an arrangement wherein torque transmitted to the lower drive assembly of the top drive unit is transmitted to the flange plate 64 while allowing for sliding displacement of the drive rods within the guide apertures of the flange plate. The driven member includes an output shaft 68 which is integrally formed with the flange plate and which defines an internal passageway 70 which is aligned with the internal passageway 40 of the central conduit segment 38 of the lower carrier structure. More specifically, a lower end region of the central conduit segment is slidably received within the internal passageway 70 at an upper region of the output shaft 68. O-ring seals 72 provide fluid-tight seals acting between the output shaft and the central conduit segment. The output shaft has a threaded socket 74 within which the externally-threaded spigot 60 of the drill pipe 62 is screw-threadingly received for connecting the drill string to the connector assembly. The lower floating connecting unit 14 includes a lower cover 76 defining a central aperture through which the output shaft 68 extends, the lower cover extending upwardly to the lower carrier plate 32 of the top drive unit where it is welded to the lower cover plate. As such, the lower cover 76 forms a housing around a lower end region of the central conduit segment, the flange plate 64 and the drive rods 42. A bottom ring 78 is provided which closes off a space between the output shaft 68 and a lower end of the lower cover plate 76. Figure 5 shows the lower floating connector unit 14 in a raised position, while Figure 6 shows the lower floating connector unit in a lowered position.

In use, sliding displacement of the drive rods 42 within the guide holes 66 of the flange plate 64 provide for attenuation of impact forces when connecting the connector assembly 10 to the drill pipe 62. During a drilling operation, it is necessary to connect and disconnect drill pipes to a connector assembly at regular intervals, for example, when additional drill pipes are added to a drill string as drilling continues at greater depths, to replace a worn drill bit, etc. With reference to Figures 9A to 9C, displacement of the lower floating connector unit 14 for attenuation of impact forces when connecting the connector assembly 10 to the drill pipe 62, is illustrated. As can be seen in Figure 9A, in order to connect the drill pipe 62 to the connector assembly 10, the connector assembly is lowered onto the drill pipe. Prior to the connector assembly contacting the drill pipe, the lower floating connector unit is in a lowered position. When lowering the connector assembly onto the drill pipe for connecting the drill pipe thereto, the operator of the drilling rig lowers the connector assembly onto the drill pipe while rotating the connector assembly. Impact forces upon contact with the drill pipe are attenuated by upward displacement of the lower floating connector unit relative to the top drive unit when contact is made with the drill pipe as is illustrated in Figure 9B. In Figure 9C, the lower floating connector unit returns to its lowered position after threaded connection between the connector assembly and the drill pipe has been completed. The floating ability of the lower floating connector unit absorbs impact due to contact between the connector assembly and the drill pipe thereby reducing damage to the threads of both the output shaft of the connector assembly and the drill pipe.

With reference to Figures 10 - 13, a second embodiment of a connector assembly in accordance with the invention, for use with a drilling apparatus used for drilling holes in a rock substrate, for connecting a drill motor of the drilling apparatus to a drill pipe of a drill string, is designated generally by the reference numeral 100. The connector assembly 100 performs the same function as the connector assembly 10 and has a similar structure to that of the connector assembly 10, with the only difference being that the connector assembly has a lower floating connector unit 114 including a flange plate 164 having guide apertures for the drive rods 42 in the form of four guide slots 166 instead of the round holes 66 of the flange plate 64 of the connector assembly 10. The guide slots 166 are in the form of radially-extending cut-outs in the flange plate which are open at a peripheral outer edge of the flange plate. As for the connector assembly 10, the drive rods 42 of the connector assembly 100 are slidably received within the guide slots 166. As such, those features of the connector assembly 100 which are the same as and/or similar to those of the connector assembly 10, are designated in Figures 10 - 13 by the same and/or similar reference numerals.