The present application claims priority from Australian Provisional Patent Application No. 2020902419 filed on 14 Jul. 2020 and Australian Provisional Patent Application No. 2020902512 filed on 20 Jul. 2020, the contents of which are incorporated herein by reference in their entirety.
The present disclosure relates, generally, to a safety apparatus for bore holes and, more particularly, to a safety plug for use in a bore hole.
Drill strings are used in the mining industry to drill long bores into rock strata for various reasons. Once the bore is drilled, the drill rods are removed so that explosives can be packed into the bore. The drill rods are removed by progressively withdrawing them from the bore and disconnecting each drill rod as it exits the bore. From time to time, drill rods can become bogged or stuck within a bore. This can occur either during drilling of the bore or during retrieval of the drill rods from the bore. While in some instances the drill rods can be dislodged from a bogged or stuck condition and can therefore be retrieved, in other instances, the drill rods become so bogged or stuck that their retrieval is not possible. In those circumstances, it is often the case that there are two or three rods left within a bore.
This presents an obvious safety issue should the rods subsequently become loose or free within the bore allowing them to fall out of the bore. If one or more drill rods were to exit a bore in this manner, any personnel or equipment standing under the open end of the bore could be struck with potentially catastrophic results.
Any discussion of documents, acts, materials, devices, articles or the like which has been included in the present specification is not to be taken as an admission that any or all of these matters form part of the prior art base or were common general knowledge in the field relevant to the present disclosure as it existed before the priority date of each of the appended claims.
In a first aspect of the present disclosure, there is provided a safety plug for use in a bore hole comprising a bore wall, the safety plug comprising: a body defining a leading end and a trailing end, the body comprising at least one flared portion, the at least one flared portion flaring outwardly from the trailing end to the leading end of the body; and an anchoring element associated with the at least one flared portion of the body, the anchoring element being axially displaceable relative to the flared portion for transitioning between an inactive condition and an active, progressively laterally expanded condition in which the anchoring element is configured to engage the bore wall to resist axial displacement of the body relative to the bore hole.
The body may be elongate and comprise a plurality of axially aligned, flared portions, each flared portion flaring outwardly towards the leading end of the body to define a flared end; and an anchoring element associated with each flared portion of the body. The body may further comprise a retaining formation proximate the trailing end, and the anchoring element associated with a flared portion adjacent the trailing end, in its inactive condition, may abut the retaining formation and the anchoring element of each remaining flared portion, in its inactive condition, may abut the flared end of a trailing flared portion.
Each anchoring element may be a radially expansible annular element arranged about its associated flared portion. Each annular element may be a split ring of a resiliently deformable material, each annular element having a roughened outer surface to resist axial displacement relative to the bore wall. Each split ring may comprise crenellations arranged at a leading side of the split ring. The crenellations may be tapered inwardly towards the body for reducing a contact area between each split ring and its associated flared portion. The crenellations may be configured to deform radially outwardly.
The leading end of the body may comprise a mounting formation and the safety plug may further comprise at least one expander element carried by the mounting formation of the body, the at least one expander element being operable to transition between an inactive condition and an active, laterally expanded condition, the at least one expander element in the active, laterally expanded condition being configured to at least partially absorb a load applied to the leading end of the body. The at least one expander element may comprise a conical body member, the conical body member defining an axially extending slot to facilitate the transition to the active, laterally expanded condition.
In an embodiment, the safety plug may comprise a plurality of expander elements, each expander element comprising a conical body member with the conical body members being arranged in a nested configuration at the leading end of the body. Adjacent nested conical body members may carry a locking arrangement comprising cooperating locking formations for interlocking the plurality of nested conical body members in their inactive condition.
The mounting formation may comprise an elongate member extending from the leading end of the body, and the, or each, expander element may be a wedge-shaped member arranged about the elongate member.
The load applied to the leading end of the body may act to transition the at least one anchoring element to the active, progressively laterally expanded condition prior to the at least one expander element transitioning to the active, laterally expanded condition, in use.
In another aspect of the present disclosure, there is provided a safety plug for use in a bore hole comprising a bore wall, the safety plug comprising: a resiliently deformable body configured to be fixedly inserted into the bore hole via an interference fit with the bore wall, the body having a tapered leading end and defining a transitioning mechanism to facilitate transitioning of the body from an inactive, insertion configuration to an, active, laterally expanded configuration.
In another aspect, there is disclosed a safety plug for use in a bore hole comprising a bore wall, the safety plug comprising:
a body having a leading end and a trailing end, the body comprising at least one flared portion, the at least one flared portion flaring outwardly in a direction from the trailing end to the leading end of the body, the body defining a longitudinal axis extending centrally therethrough between the leading end and the trailing end;
an anchoring element extending at least partially around the least one flared portion of the body, the anchoring element being axially displaceable relative to the flared portion for transitioning the anchoring element, as a result of the anchoring element bearing against the at least one flared portion, between an unexpanded condition in which the anchoring element is closer to the longitudinal axis and an expanded condition in which the anchoring element is further from the longitudinal axis; and
a nose extending longitudinally from the leading end of the body, the nose being longitudinally compressible.
The nose may be longitudinally compressible and laterally expansible.
In some embodiments, the at least one flared portion comprises a plurality thereof, the flared portions being aligned on the longitudinal axis; and each of the flared portions has an associated said anchoring element. In some embodiments, the body further comprises a retaining formation proximate the trailing end for abutment by the anchoring element associated with the flared portion closest the trailing end to retain that anchoring element in a position forwardly of the retaining formation, and wherein abutment of each of the other anchoring elements with a flared end of an adjacent, trailing said flared portion retains each of the other anchoring elements in a position forwardly of its associated adjacent, trailing said flared portion.
In some embodiments, each said anchoring element is a radially expansible annular element. Each said annular element may be a split ring of a resiliently deformable material. Each said anchoring element may comprise crenellations arranged at a leading end thereof. The leading end of each of the crenellations may be tapered inwardly. The crenellations may be configured to splay outwardly in response to axial displacement of the anchoring element toward a leading end of the associated flared portion.
The nose may be operable to transition between an inactive condition and an active condition to at least partially absorb a force applied to a leading end of the safety plug, a length of the nose being lesser and a width of the nose being greater in the active condition than in the inactive condition.
The nose may comprise a conical body member. An axially extending slot may be provided in the conical body member to facilitate lateral expansion of the conical body member. The safety plug may comprise a plurality of the conical body members, the conical body members being arranged in a nested configuration at the leading end of the body. The conical body members may have cooperating locking formations for releasably interlocking the plurality of nested conical body members against axial displacement relative to one another. The cooperating locking formations may be configured to disengage in response to application of a compressive force to the nose. The safety plug may be configured such that, prior to the cooperating locking formations disengaging, each said anchoring element is configured to commence displacement toward a leading end of the associated flared portion in response to the application of the compressive force to the nose.
The safety plug may be configured such that, with the anchoring element(s) restrained against displacement along the longitudinal axis but free to expand laterally, application of a compressive force to the nose initiates expansion of the anchoring element(s) before initiating compression of the nose.
Each said anchoring element and each said flared portion may be of a harder material than the nose.
Each said anchoring element and each said flared portion may be of a hard material, such as a material having a Rockwell hardness of approximately M88.
The nose may be of a medium soft material, such as a material having a Shore hardness of approximately A90.
Throughout this specification the word “comprise”, or variations such as “comprises” or “comprising”, will be understood to imply the inclusion of a stated element, integer or step, or group of elements, integers or steps, but not the exclusion of any other element, integer or step, or group of elements, integers or steps.
Embodiments of the disclosure will now be described by way of example only with reference to the accompanying drawings in which:
In the drawings, reference numeral 10 generally designates an embodiment of a safety plug for use in a bore hole 12 comprising a bore wall 14.
The body 22 of the safety plug 10 comprises a plurality of axially aligned, flared portions 32 arranged in end-on abutting relationship. Each flared portion 32 flares outwardly towards the leading end 24 of the body 22 to define a flared leading end 34. In this embodiment, each flared portion 32 of the body 22 defines a passage 31 through which the shank 23 extends to mount the flared portions 32 on the shank 23. The body 22 of the safety plug 10 further includes a retaining arrangement in the form of a retaining washer 45 and threaded nut 43, which are secured to the threaded portion 30 at the trailing end 25 of the shank 23 to retain the flared portions on the shank 23. It will be appreciated that, in another embodiment (not shown), the flared portions 32 may be of unitary, one piece construction with each other and, in some embodiments, with the shank 23.
The safety plug 10 further comprises an anchoring elements in the form of annular elements, more specifically, split rings 36, each split ring 36 being axially slidably mounted on a respective flared portion 32. Each split ring 36 is radially expansible and has an inner surface that defines a seat 33 for engagement with the conical surface of the respective flared portion 32. Axial displacement of split ring 36 from the trailing end toward the leading end of its associated flared portion 32 transitions split ring 36 from an inactive, installation condition (
Each flared portion 32 and each anchoring element 36 is of a hard material which is able to withstand high impacts, such as a suitable synthetic plastics material. Each flared portion 32 and each anchoring element 36 being of a hard material also contributes to reduced friction between these components. In an embodiment, each flared portion 32 and each split ring 36 is of an engineering plastics material, such as a high density polyamide, which is abrasion resistant, resistant to compression but has flexibility. For example, each flared portion 32 and each split ring 36 may be of ‘Nylon 6’ having a Rockwell hardness of M88. Further, each split ring 36 has a roughened outer surface to enhance frictional engagement with the bore wall 14 as shown schematically by arrows 37 in
Traversal of the split ring 36 towards the leading end 34 of its associated flared portion 32 causes the split ring 36 to expand and become wedged between its associated flared portion and the bore wall 14. thereby This wedging action inhibits axial displacement of the body 22 of safety plug 10 towards an opening of the bore hole 12 in response to an applied load 51 (
In an embodiment, and as shown in
An embodiment of split ring 36 will now be described in detail with reference to
Split ring 36 has an annular part 76 carrying a plurality of circumferentially spaced crenellations 44. Each crenellation 44 has an operatively inner side 44.1, being the side which faces the associated flared portion 32 of the body 22, and an operatively outer side 44.2, being the side which faces the wall of the bore hole 12. The inner side 44.1 has a first taper 71 and outer side 44.2 has a second taper 72. The tapers 71 and 72 are asymmetrical, with the taper 71 being shorter than the taper 72, which facilitates outward deformation of the crenellations 44 as the split ring 36 moves from the trailing end to the leading end of its associated flared portion 32 in response to safety plug 10 being impacted by a falling drill rod. In the configuration shown in
The annular part 76 of the split ring 36 between adjacent crenellations 44 is radiused, defining smoothly curved transition portions 78. The smoothly curved transition portions 78 inhibit stress fractures between adjacent crenellations 44. In addition, the transition portions 78 define a surface 80 which is angled downwardly from an operatively outer wall 82 of the annular part 76 to the operatively inner wall 74 of the annular part 76. The angling of surface 80 facilitates outward deformation of the crenellations 44 as the split ring 36 moves from the trailing end to the leading end of its associated flared portion 32 in response to the safety plug 10 being impacted by a falling drill rod. An included angle between surface 80 of split ring 36 and the longitudinal axis of the associated flared portion 32 is between about 60° and about 90°, typically being about 70°.
In an embodiment in which the annular part 76 of the split ring 36 has an outer diameter of approximately 90 mm and a height of the split ring 36 from its trailing end to its leading end is about 40 mm, the transition portions 78 may have a radius of about 11 mm.
Referring again to
In an embodiment, the body 22 of the safety plug 10 can be used on its own to inhibit displacement of a stuck drill rod 20. In such an embodiment, the body 22 may be driven into the bore hole 12 until the conical element 28 of the safety plug 10 abuts the proximal end of the stuck drill rod 20.
More typically, as shown in
As will be described in greater detail below, the nested conical body members 46 are operable to transition between an inactive condition (
The locking arrangement 52, 54 may adopt various forms. In the embodiment shown in
In the embodiment shown in
In an alternate embodiment of the safety plug 10, as shown in
In use, the safety plug 10 is inserted into the bore hole 12 using the drilling machine 16 which bears against the nut 43 to urge the safety plug 10 at least 150 cm into the bore hole 12. It will, however, be appreciated that the safety plug 10 could be inserted further into the bore hole 12, up to and including abutting to a depth at which the safety plug abuts the proximal end of the stuck drill rod 20.
A range of safety plugs 10 is provided, each for bore holes 12 of different diameters. It will be appreciated that a safety plug 10 of appropriate size for a bore hole 12 will have split rings 36 that, in the absence of an external force, have an outer diameter greater than that of bore hole 12. However, the split rings 36 have an inner diameter that is sufficiently greater than that of the trailing end of the flared portions 32 to permit the split rings to be elastically radially compressed to match the diameter of the bore hole 12. Moreover, a safety plug 10 of appropriate size for a bore hole 12 will have flared portions 32 and conical body members 46 that have a diameter less than that of the bore hole 12. After selecting a safety plug 10 of appropriate size, the safety plug 10 is inserted into the bore hole 12 with the split rings 36 and the conical body members 46 in their respective inactive conditions (
Response of safety plug 10 to impact by a falling drill rod 20 is shown schematically in
Further applied force from the falling drill rod 20 is absorbed and dispersed by the conical body members 46 being compressed against the body 22. Locking arrangement 52, 54 is configured to disengage when this compression reaches approximately 50 kg. Following disengagement of locking arrangement 52, 54, the conical body members 46 to transition from their inactive condition, as shown in
Split ring 36′ of
Split ring 36″ of
Advantageously, the safety plug 10 aids in arresting movement of the falling drill rod 20 and substantially reduces the likelihood of injuring personnel or damaging equipment in the underground passage 18. The use of a multi-stage process using a combination of frictional engagement and force dissipation via elastic and plastic deformation advantageously increases the likelihood of the safety plug 10 arresting movement of the falling rod 20.
It will also be appreciated that, when mine personnel are aware of the existence of a stuck drill rod, steps have to be taken to protect operating personnel. This results in that area of a mine having to be closed until the stuck drill rod has been dealt with. A safety plug 10 in accordance with the described embodiments of this disclosure assists in rapidly dealing with this problem.
It will be appreciated by persons skilled in the art that numerous variations and/or modifications may be made to the above-described embodiments, without departing from the broad general scope of the present disclosure. The present embodiments are, therefore, to be considered in all respects as illustrative and not restrictive. Examples of such variations and/or modifications include:
anchoring elements 36 being a closed annulus (i.e., a ring without a split);
crenellations 44 being omitted from anchoring elements 36; and/or
safety plug 10 may have a light or light reflector, such as a retroreflector, on its trailing end.
Number | Date | Country | Kind |
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2020902419 | Jul 2020 | AU | national |
2020902512 | Jul 2020 | AU | national |
Filing Document | Filing Date | Country | Kind |
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PCT/AU2021/050755 | 7/14/2021 | WO |