AU2009203062A1

AU2009203062A1 - Device for locating an explosives package in a borehole

Info

Publication number: AU2009203062A1
Application number: AU2009203062A
Authority: AU
Inventors: Richard John Johnson
Original assignee: Johnson Hi Tech Australia Pty
Current assignee: Johnson Hi Tech Australia Pty
Priority date: 2009-07-29
Filing date: 2009-07-29
Publication date: 2011-02-17

Description

P/00/011 Regulation 3.2 AUSTRALIA Patents Act 1990 ORIGINAL COMPLETE SPECIFICATION STANDARD PATENT Invention Title: "DEVICE FOR LOCATING AN EXPLOSIVES PACKAGE IN A BOREHOLE" The following statement is a full description of this invention, including the best method of performing it known to me/us: 1 TITLE DEVICE FOR LOCATING AN EXPLOSIVES PACKAGE IN A BOREHOLE 5 FIELD OF THE INVENTION THIS INVENTION relates generally to means for facilitating the location of explosives packages in boreholes and, in particular, to a device commonly referred to as a "spider", for locating elongate tubular explosives packages in a borehole. 10 BACKGROUND OF THE INVENTION It is well known to package explosives compositions used in mining applications, in purpose designed containers to produce explosives "packages" which can readily be transported and handled. The explosives 15 composition comprises dry powder or granulated compounds, emulsions, slurries, water gels, or the like, and the packages may be adapted to suit charge mass, borehole diameter, borehole length, and the like. British Patent 1281421 describes packaging of an ammonium nitrate explosive in a thin flexible plastic sheath such as polyethylene. The patent 20 specification states that explosive charges can be inserted into boreholes at up to 600 from vertical and moreover that with the aid of a bracket shaped slide, these packages can be inserted into horizontal boreholes. Inserting soft, thin walled explosives packages is a difficult and time consuming task, particularly for horizontal boreholes because such packages 25 are even more prone to puncturing and tearing when pushed into a horizontal cavity. Of more recent times they have been replaced with a semi rigid plastics tube of a material such as polyethylene with a wall thickness of about 1 mm. Such tubes serve to ameliorate, but do not overcome, the above problems. 30 Australian patent application 2004200371 which has the same inventor as the present application, describes a spider for locating an elongate tubular explosives cartridge in a borehole. The spider comprises a 2 mounting collar which can be secured about an explosives cartridge, and which supports radially extending, resiliently deformable fingers. In use, the collar is anchored to the explosives cartridge by a detonator which extends into the cartridge. 5 SUMMARY OF THE INVENTION It is an aim of the present invention to overcome or ameliorate at least some of the prior art problems associated with thin walled, tubular explosives packages, and/or otherwise to provide users with a convenient choice. 10 According to the invention there is provided a spider device for locating an elongate tubular explosives cartridge in a borehole, said spider device comprising: a mounting collar, in use securable about an outer surface of an elongate tubular explosives cartridge, the collar being deformable and 15 thereby size-adjustable to accommodate explosives cartridges of different diameters; a plurality of spaced, substantially radially extending legs supported by the mounting collar, and resiliently deformable to permit the spider device to be accommodated in a borehole having a diameter smaller than a diameter 20 of the spider device when the radially extending legs are in an undeformed state; and a retaining means on the mounting collar for retaining the collar in a selected size-adjusted configuration and thereby, in use, retaining the spider device on the explosives cartridge. 25 The retaining means may include interengageable retaining formations which can be urged into engagement with each other by deformation of the collar to a size-adjusted configuration. In a preferred embodiment, the retaining means comprises two arms which extend towards each other from opposite ends of the collar, and 30 overlap with each other when the collar is in a size-adjusted configuration. The arms may resemble lobster claws in that each may comprise opposed, spaced apart retaining members, one of the members of each arm being 3 receivable between the retaining members of the other arm when the collar is in its size-adjusted configuration. At least one of the members of each arm may have retaining formations, the retaining formations on one of the arms being engageable 5 with the retaining formations on the other arm when the collar is deformed, thereby to retain the collar in its size-adjusted configuration. Preferably the retaining formations are located on an inner wall of one of the retaining members of each arm. The retaining means may further include locking means for locking the 10 retaining formations on the one arm in engagement with the retaining formations on the other arm. In a preferred embodiment of the spider device, the locking means comprises a tongue and groove arrangement, the groove being defined by one of the retaining members of the one arm, and the tongue being provided on the other arm so that it projects from one of the 15 retaining members towards the other, and is receivable in the groove when the collar is in its size-adjusted configuration. Thus, when the collar is in its size-adjusted configuration, the tongue effectively urges the retaining formations on the respective arms into engagement with each other so as to lock them together. 20 Each of the legs may have a foot which forms an obtuse angle with the leg, and a reinforcing web between the collar and each leg. These features serve to preserve the integrity of the spider device in use, and increase its efficacy in locating the explosives cartridge centrally of the borehole. 25 BRIEF DESCRIPTION OF THE DRAWINGS The spider device of the invention (hereinafter "spider") is now described by way of the following non-limiting example, and with reference to the drawings in which: 30 Figure 1 is a three dimensional view of a spider according to the invention in an undeformed configuration; Figure 2 is a plan view of the spider of Figure 1; 4 Figure 3 is a three dimensional view of the spider of Figures 1 and 2, having a collar which is locked in a deformed, size-adjusted configuration on a section of an explosives cartridge, prior to locating the cartridge in a borehole; and 5 Figure 4 is a three dimensional view of the spider and the section of the explosives cartridge shown in Figure 3, as the cartridge is being located in a borehole. DETAILED DESCRIPTION OF THE DRAWINGS 10 The present invention relates to means for facilitating the location of explosives packages in boreholes and, in particular, the invention provides a spider device ("spider") for locating an elongate tubular explosives package in a borehole. The spider comprises a mounting collar, in use securable about an outer surface of an elongate tubular explosives cartridge. The collar 15 is deformable and thereby size-adjustable to accommodate explosives cartridges of different diameters. A plurality of spaced, substantially radially extending legs are supported by the mounting collar, and are resiliently deformable to permit the spider to be accommodated in a borehole having a diameter smaller than a diameter of the spider when the radially extending 20 legs are in an undeformed state. A retaining means on the mounting collar serves to retain the collar in a selected size-adjusted configuration and thereby, in use, retain the spider on the explosives cartridge. Embodiments of the present invention are effective in holding a tubular explosives cartridge in a position which is generally central of the 25 borehole. They also facilitate the charging of boreholes with elongate tubular explosives cartridges, thereby providing a cost saving advantage arising from a more convenient and less labour intensive procedure. Furthermore, they better preserve the integrity of the cartridges as the cartridges are being pushed into the boreholes, by protecting the walls thereof against tearing on 30 the sides of the borehole. An embodiment of the present invention is now described, and elements thereof are illustrated in concise outline form in the drawings, 5 showing only those specific details that are necessary for understanding the embodiment, but so as not to clutter the disclosure with excessive detail that will be obvious to those of ordinary skill in the art in light of the present description. 5 In this patent specification, references to "rearward" and "forward", etc. are used solely to distinguish between elements or directions or method steps without necessarily requiring a specific relative position or sequence that is suggested thereby. Further, words such as "comprises" or "includes" are not used to define an exclusive set of elements or method steps. Rather, 10 such words merely define a minimum set of elements or method steps included in a particular embodiment of the present invention. Figure 1 is a three dimensional view of a spider 10 according to the invention in an undeformed configuration, and Figure 2 is a plan view thereof. The spider 10 is for locating an elongate tubular explosives cartridge 15 centrally of a borehole. The spider 10 comprises a mounting collar 16 in the form of an open circular band with a plurality of generally radially extending legs 18 which are resiliently deformable. The spider 10 has an outer diameter greater than the diameter of the borehole for which it is intended. The collar 16 is deformable and thereby size-adjustable to accommodate 20 explosives cartridges of different diameters. The spider 10 includes a retaining means 20 comprising arms 22, 24 on said mounting collar 16, for retaining the collar 16 in a selected size-adjusted configuration and thereby, in use, for retaining the spider 10 on an explosives cartridge. The arms 22, 24 resemble lobster claws which extend towards each other from opposite 25 ends of the collar 16. Each of the claws 22, 24 has two opposed, spaced apart, members 22.1, 22.2 and 24.1, 24.2. Complementary, interengageable retaining formations 26, 28, are located on respective inner walls of the retaining members 22.1, 24.1. The retaining means 20 further includes locking means for locking the 30 retaining formations 26 on the arm 22 in engagement with the retaining formations 28 on the other arm 24. The locking means comprises a tongue 6 and groove arrangement, the groove 30 (Figure 1) being defined by retaining member 24.1, and the tongue 32 (Figure 2) being provided on the arm 22 so that it projects from the retaining member 22.2 towards the retaining member 22.1. The tongue 32 is receivable in the groove 30 when the collar 16 is in its 5 size-adjusted configuration. Each of the legs 18 has a forward extending foot 34 which forms an obtuse angle with the leg 18, and a reinforcing web 36 between the collar 16 and the forward facing surface 37 of each leg 18. Figure 3 is a three dimensional view of the spider 10 with the collar 16 10 in a deformed, size-adjusted configuration on an explosives cartridge 38. When the collar is in this configuration, the claws 22, 24 overlap with each other; one of the members 22.1, 24.1 of each claw 22, 24 is receivable between the two members of the other claw 24, 22; the complementary retaining formations 26, 28, engage each other; and the tongue 32 is 15 received in the groove 30. The collar 16 is thus locked in the size-adjusted configuration, on the cartridge 38. (The retaining formations 26, 28, and the tongue 32 and groove 30, cannot be seen when the collar 10 is secured on the cartridge 38 as shown in Figure 3.) Figure 4 is a three dimensional view of the spider 10 and the section 20 of the explosives cartridge 38 shown in Figure 3, as the cartridge 38 is being located in a borehole 40. A typical cartridge 38 comprises a semi-rigid polyethylene tube with a preferred wall thickness of about 1.00mm and a length of between 2 and 5 metres, which contains a fluent explosives composition having a desired compaction and density. 25 The legs 18 of the spider 10 can flex in a direction which is rearward of the direction of movement of the spider 10, in use, as the explosives cartridge 38 is pushed into the borehole 40 in a direction indicated by arrow 42. The forward extending foot 34 on each of the legs 18, and the reinforcing web 36 between the collar 16 and the forward facing surface 37 of each leg 30 18, assist to preserve the integrity of the spider 10 as it is forced, with the explosives cartridge 38, into the borehole 40, and they thereby increase the efficacy of the spider 10 in locating the cartridge 38 centrally of the borehole 7 40. In use, (see Figures 3 and 4), the spider 10 is placed over the cartridge 38. The collar 16 is then deformed and thereby reduced in size by urging the retaining claws 22, 24 towards each other so that each of the 5 retaining members 22.1, 24.1 is located between the members 24.1 24.2 and 22.1, 22.2, respectively, of the other claw 24, 22. The retaining formations 26 on the claw member 22.1 engage with the complementary retaining formations 28 on the claw member 24.1, and the tongue 32 is received in the groove 30. The tongue 32 effectively urges the retaining formations 26, 28 10 on the respective claws 22, 24 into engagement with each other, and the collar 16 is thereby locked in its size-reduced configuration. (The retaining formations 26, 28, and the tongue 32 and groove 30 cannot be seen when the spider 10 is secured on the cartridge 38 as shown in Figures 3 and 4.) A number of spiders 10 are spaced at appropriate intervals along an 15 elongate tubular explosives cartridge 38, and the cartridge 38 is then pushed into a borehole 40 in the direction indicated by arrow 42. Appropriate intervals are determined according to what may be required to hold a cartridge of a particular length, diameter and mass, centrally of a borehole 40 for which it has been designated. As the cartridge 38 with the spiders 10 20 secured thereto, are inserted into the borehole 40 in the direction 42, the legs 18 are flexed rearward relative to the direction 42. Rearward flexing of the legs 18 creates a resilient restoring force in the legs so that, in use, the legs 18 are urged against the wall/s 44 of the borehole 40, thereby to retain the spider 10, and hence the cartridge 38, generally centrally of the borehole 25 40. Advantages of the spider according to the invention, at least as exemplified, include the relatively robust construction of the legs, particularly where they meet the collar, which promotes integrity of the spider in use, and hence its efficacy in holding a tubular explosives cartridge in a position which 30 is generally central of the borehole. The spider also facilitates charging of boreholes with elongate tubular explosives cartridges, which provides a cost saving advantage arising from a more convenient and less labour intensive 8 procedure. Furthermore, they better preserve the integrity of the cartridges as the cartridges are being pushed into the boreholes, by protecting the polyethylene cartridge walls against tearing on the sides of the borehole. The above description of an embodiment of the present invention is 5 provided for purposes of description to one of ordinary skill in the related art. It is not intended to be exhaustive or to limit the invention to a single disclosed embodiment. Numerous alternatives and variations to the present invention will be apparent to those skilled in the art of the above teaching. Accordingly, while a particular embodiment has been discussed specifically, 10 other embodiments will be apparent or relatively easily developed by those of ordinary skill in the art. Accordingly, this patent specification is intended to embrace all alternatives, modifications and variations of the present invention that have been discussed herein, and other embodiments that fall within the spirit and scope of the above-described invention.

Claims

1. A spider for locating an elongate tubular explosives cartridge in a borehole, said spider comprising: 5 a mounting collar, in use securable about an outer surface of an elongate tubular explosives cartridge, the collar being deformable and thereby size-adjustable to accommodate explosives cartridges of different diameters; a plurality of spaced, substantially radially extending legs supported by 10 the mounting collar, and resiliently deformable to permit the spider to be accommodated in a borehole having a diameter greater than said elongate tubular explosives cartridge and smaller than a diameter of said spider when the radially extending legs are in an undeformed state; and a retaining means on said mounting collar for retaining the collar in a 15 selected size-adjusted configuration and thereby, in use, retaining the spider on the explosives cartridge.

2. A spider as claimed in claim 1 wherein the retaining means includes interengageable retaining formations which can be urged into engagement 20 with each other by deformation of the collar to a size-adjusted configuration.

3. A spider as claimed in claim 1 wherein the retaining means comprises a first arm and a second arm, and the first and second arms extend towards each other from opposite ends of the collar, and overlap with each other 25 when the collar is in a size-adjusted configuration.

4. A spider as claimed in claim 3 wherein each of the arms comprises opposed, spaced apart retaining members, one of the members of each arm being receivable between the retaining members of the other arm when the 30 collar is in its size-adjusted configuration.

5. A spider as claimed in claim 4, wherein at least one of the members of 10 each arm has retaining formations, and the retaining formations on one of the arms are engageable with the formations on the other arm when the collar is deformed, thereby to retain the collar in a size-adjusted configuration. 5

6. A spider as claimed in claim 5, wherein the retaining means further includes a tongue and groove arrangement for locking the retaining formations on the one arm in engagement with the retaining formations on the other arm, the groove being defined by one of the retaining members of 10 the one arm, and the tongue being provided on the other arm so that it projects from one of the retaining members towards the other, and is receivable in the groove when the collar is in its size-adjusted configuration.

7. A spider as claimed in any of claims 1-6, wherein each of the legs 15 has a foot which forms an obtuse angle with the leg, the foot serving to strengthen the leg in use.

8. A spider as claimed in any one of claims 1-7, which includes a reinforcing web between the mounting collar and each of the legs, the web 20 serving to preserve the integrity of the spider in use.

9. A spider substantially as hereinbefore described with reference to the accompanying drawings.