AU2007205818B2 - Blast plug - Google Patents

Abstract

The present invention relates to a blast plug (10) that allows easy positioning in a drilled hole prior to blasting. In accordance with one aspect of the present invention there is provided a blast plug (10) for sealing a hole drilled in a substantially horizontal surface comprising a body having a connection point (12) for connection to an elongate suspension means such as a rope (14), a first end (16) and a second end (18), the first end (16) of the body being connected to the second end (18) along a hinge axis (20), the first end (16) and the second end (18) being pivotable relative to one another about the hinge axis (20) such that when the body hangs from the connection point (12), the hinge axis (20) is generally horizontal.

Description

AUSTRALIA PATENTS ACT 1990 COMPLETE SPECIFICATION FOR A STANDARD PATENT (Original) APPLICATION NO: LODGED: COMPLETE SPECIFICATION LODGED: ACCEPTED: PUBLISHED: RELATED ART: NAME OF APPLICANT: Peter Bryce Catoi ACTUAL INVENTOR: Peter Bryce Catoi ADDRESS FOR SERVICE: LORD AND COMPANY, Patent and Trade Mark Attorneys, of 4 Douro Place, West Perth, Western Australia, 6005, AUSTRALIA. INVENTION TITLE: Blast Plug DETAILS OF ASSOCIATED PROVISIONAL APPLICATION NO'S: Australian Provisional Patent Application Number 2006904430 filed on 16 August 2006 The following Statement is a full description of this invention including the best method of performing it known to me: TITLE "BLAST PLUG" FIELD OF THE INVENTION The present invention relates to a blast plug. Blast plugs are required to be used in the mining industry as part of the process for creating a substantially vertical shaft by blasting. In a standard process, a substantially vertical hole is drilled downwardly along the path to be created. A blast plug is inserted down the hole until it passes out the lower end of the hole. The blast plug is generally attached to a rope to allow it then to be pulled upwards to block the end of the hole, into which can then be placed explosive material for detonation. Any suitable material or device at hand may be used for the blast plug and it is not uncommon for the blast plug to simply comprise a rag or similar device forced down the hole with a rod. The present invention relates to a blast plug that allows positioning in a drilled hole prior to blasting. SUMMARY OF THE INVENTION In accordance with one aspect of the present invention there is provided a blast plug 0 for sealing a hole drilled in a substantially horizontal surface comprising a body having a connection point for connection to an elongate suspension means, and first and second ends, the first end of the body being connected to the second end of the body along a hinge axis, the first and second ends being pivotable relative to one 2 another about the hinge axis such that when the body hangs from the connection point, the hinge axis is generally horizontal. In accordance with a further aspect of the present invention there is provided a method of sealing a hole drilled in a substantially horizontal surface utilising a blast plug in accordance with the present invention which comprises; attaching an elongate suspension means to the connection point on the blast plug, inserting the blast plug downwardly into the hole with the first or second end foremost, pushing the blast plug, allowing the blast plug to rotate when it exits the hole such that the hinge axis is oriented approximately horizontally, pulling upwardly on the suspension means such that the first and second ends of the blast plug engage with a lower end of the hole, and further pulling upwardly on the suspension means such that the first and second ends pivot towards each other to create a seal across the hole. BRIEF DESCRIPTION OF THE DRAWINGS The present invention will now be described, by way of example, with reference to the accompanying drawings, in which: Figure 1 a is an upper perspective of a blast plug in accordance with the present invention; Figure lb is a lower perspective view of the blast plug of Figure Ia; Figure Ic is a top view of the blast plug of Figure Ia; Figure Id is a side view of the blast plug of Figure Ia; 3 Figure 1 e is an end view of the blast plug of Figure Ia; Figure 2a is an upper perspective view of the blast plug of Figure I a in a compressed state; Figure 2b is a lower perspective view of the blast plug of Figure la in a compressed state; Figure 3a is a view of the blast plug of Figure 1 being inserted downwardly into a drilled hole; Figure 3b is a view of the blast plug of Figure 1 exiting from the lower end of the drilled hole; and Figure 3c is a view of the blast plug of Figure 1 being pulled upwardly to seal across the lower end of the hole. DESCRIPTION OF THE INVENTION Referring to the Figures, there is shown a blast plug 10 for sealing across the lower end of a drilled hole as shown in the method of Figures 3a to 3c. The blast plug 10 includes a connection point 12 to which is attached, in use, a flexible elongate suspension means such as a rope 14. The blast plug 10 comprises a body having a first end 16 and a second end 18. The first end 16 and the second end 18 are connected together along a hinge axis 20. The connection point 12 is located 0 generally on the hinge axis 20 and the first and second ends 16 and 18 extend generally downwardly and away from each other as shown in Figure Id when the blast plug 10 is suspended. A wedge shaped space 22 is thereby defined between the first and second ends 16 and 18. 4 The body of the blast plug 10 is expected to be constructed of a flexible resilient material such as polyurethane foam. This flexibility provides hinged movement between the first and second ends 16 and 18 about the hinge axis. The first and second ends 16 and 18 each include a first portion 24 adjacent the connection point 12. The first portions 24 are each shaped in a generally half cone or dome shape but in which the axis of the cone or dome is angled outwardly from a vertical axis by an amount approximately equal to the angle of the sides of the wedge shaped space 22 from the vertical. With this shape, when the first and second ends 16 and 18 are pivoted towards each other until the first and second ends 16 and 18 come into contact, the first portions 24 define a sealing portion 40 of an approximate cone or dome shape. That is the first portions 24 form a shape having a circular cross sectional shape about the axis of the rope 14, tapered towards the connection point 12 (as shown in Figures 2a and 2b). The shape of the body of the blast plug 10 when viewed along a longitudinal axis 30 (see Figure lc) perpendicular to a vertical plane passing through the hinge axis 20 is generally circular, as can be seen in Figure le. The diameter of the circular cross section along the longitudinal axis 30 is less than the diameter of the hole through which the blast plug is to be inserted. The use of the pivoting first and second ends 16 and 18 of the body of the blast plug 10 allows the cross sectional diameter along the longitudinal axis 30 to be less than that of the hole, while allowing the first portions 24 to be sufficiently large to block the hole. Each of the first and second ends 16 and 18 includes a second portion 26 extending outwardly from the first portions 24. The second portions 26 each include recesses 28 in longitudinal ends thereof. The recesses 28 are provided to receive a push rod 29. 5 The push rod 29 engages in one of the recesses 28 in use to allow the blast plug 10 to be pushed down the hole. The first and second ends 16 and 18 each also include a groove 32 running parallel to the longitudinal axis 30 outwardly from the connection point 12. The grooves 32 are provided for receiving the rope 14. In use, the blast plug 10 is inserted downwardly into the hole with the longitudinal axis 30 parallel to the direction of the hole as shown in Figure 3a. The rope 14 is received in one of the grooves 32 when the blast plug is in this orientation, as can be seen in Figure 3a. The blast plug 10 is pushed down the hole by engaging a push rod 29 in the uppermost of the recesses 28. When the blast plug 10 exits the lower end of the hole, it rotates approximately 90 degrees due to its shape such that the hinge axis 20 is oriented approximately horizontally (as shown in Figure 3b). The rope 14 is then pulled upwardly and the first portions 24 of the first and second ends 16 and 18 engage with the lower end of the hole. This engagement causes the first and second ends 16 and 18 to pivot towards each other, creating the sealing portion 40 of the shape as described above. The sealing portion 40 seals across the hole as shown in Figure 3c. The compressibility of the blast plug 10 allows the blast plug to be compressed into the hole, retaining its position in the hole when released. The hole can then be filled with suitable explosive D material and blasted in a known manner. Modifications and variations as would be apparent to a skilled addressee are deemed to be within the scope of the present invention 6

Claims (14)

1. A blast plug for sealing a hole drilled in a substantially horizontal surface comprising a body having a connection point for connection to an elongate suspension means, and first and second ends adapted to abut a surface of the hole , the first end of the body being connected to the second end of the body along a hinge axis, the first and second ends being pivotable relative to one another about the hinge axis such that when the body hangs from the connection point, the hinge axis is generally horizontal, wherein the blast plug is arranged to abut and seal the hole by pivoting the first and second ends toward one another.

2. A blast plug according to claim 1, wherein the first and second ends extend generally downwardly and away from each other when the body hangs from the connection point.

3. A blast plug according to claim 1 or 2, wherein the first and second ends each comprise a groove extending outwardly from the connection point, the grooves being arranged to receive the elongate suspension means.

4. A blast plug according to claim 3, wherein the grooves are arranged to receive a rope.

5. A blast plug according to any one of the preceding claims, wherein each end comprises a first portion adjacent the connection point shaped such that when the first 7 and second ends are pivoted toward each other , the first portions define a sealing portion of generally circular cross section centred about the connection point.

6. A blast plug according to claim 5, wherein the first portions are each shaped in a generally half cone or dome shape.

7. A blast plug according to claim 6, wherein when the first and second ends are pivoted towards each other until they are in contact with one another, the first portions define a sealing portion of an approximate cone or dome shape.

8. A blast plug according to any one of claims 5 to 7, wherein each of the first and second ends includes a second portion extending outwardly from the respective first portion wherein the second portions each include a recess.

9. A blast plug according to claim 8, wherein the recesses are able to be engaged with a push rod to allow the blast plug to be pushed down a hole.

10. A blast plug according to any one of the preceding claims, wherein pivoting the first and second ends about the hinge axis allows the first portions to enable the blast plug to block the hole.

11. A blast plug according to any one of the preceding claims, wherein the device is constructed of a flexible resilient material. Sz

12. A method of sealing a hole drilled in a substantially horizontal surface utilising a blast plug according to claim 1, which comprises: attaching an elongate suspension means to the connection point on the blast plug, inserting the blast plug downwardly into the hole with the first or second end foremost, pushing the blast plug through the hole, allowing the blast plug to rotate when it exits the hole such that the hinge axis is oriented approximately horizontally, pulling upwardly on the suspension means such that the first and second ends of the blast plug engage with a lower end of the hole, and further pulling upwardly on the suspension means such that the first and second ends pivot towards each other to create a seal across the hole.

13. A blast plug substantially as herein before described with reference to the accompanying drawings.

14. A method of sealing a hole substantially as herein before described with reference to the accompanying drawings.