AU725158B2 - Apparatus for plugging a hole - Google Patents

Description

49991 DP:MNP/0 11 Regulation 3.2

AUSTRALIA

Patents Act 1990 COMPLETE SPECIFICATION FOR A STANDARD PATENT

ORIGINAL

Nam ofApiat N o: SPC

MC

Adrs fo Sevie COLIO O,17Kn ila tet dlie Ineto Title APAAU FO.LUGN.AHL The folwn ttmnCsafl ecitino hsivnin nldn h bes meho ofpromn tkont s 0 9 **BACKGROUND OF THE NENTION THIS invention relates to apparatus for plugging a hole.

*:Owe, In certain blasting operations, boreholes are drilled and explosive charges are inserted into the holes. For successful blasting, the explosive charges should be located at the correct depths in the boreholes.

Various plugs have been provided for this purpose. However, many of the known plugs are difficult to locate accurately in boreholes, or do not seat securely in use.

It is an object of the invention to provide a relatively simple apparatus whichfor plugging a hole.

n plug certain blasting op a secure mannerboreholes are drilled and explosivcated at a selected inserted int the holes. For successful blasting the explosive charges should S 5 be located at the correct depths in the boreholes.

Various plugs have been provided for this purpose. However, many of the known plugs are difficult to locate accurately in boreholes, or do not seat securely in use.

It is an object of the invention to provide a relatively simple apparatus which can plug a hole in a secure manner and which can be located at a selected depth in the hole.

SUMMARY OF THE INVENTION According to the invention there is provided apparatus for plugging a hole, the apparatus comprising: an inflatable body; 5 inflation means for inflating the body; and i 0 S inflation restraining means for temporarily preventing or *,restraining distension of the body once the inflation means has been activated so that the body can be lowered into the hole in a substantially deflated or only partially inflated condition, the 10 inflation restraining means being arranged to fail at a predetermined pressure so as to allow the body to become substantially fully distended and consequently wedged within the hole.

The inflation means is preferably a gas-filled canister located within the 15 inflatable body.

oo The inflation restraining means may be in the form of a sealed enclosure surrounding the canister and located within the inflatable body. The sealed enclosure may be formed from a flexible, gas impervious plastics material.

Alternatively, the inflation restraining means may be a sleeve or strap which is arranged to fit around the inflatable body when the body is in a substantially deflated condition.

-4- The inflatable body is preferably in the form of a bladder comprising a flexible, gas impervious plastics material.

The apparatus preferably includes a protective outer cover to cover the inflatable body. The outer cover preferably defines an aperture to allow a user 5 access to the inflation means.

S* The apparatus may also include at least one wedge member associated with the body and arranged to move from a retracted position to an extended position when the body is inflated, thereby to wedge the body in the hole.

The at least one wedge member may be a plurality of rigid elongate members disposed at an end of the body in the manner of umbrella spokes.

Each rigid elongate member may be located in a sleeve formed on the body, and preferably extends beyond the body in the extended position thereof.

*0 BRIEF DESCRIPTION OF THE DRAWINGS The invention will now be described in more detail, by way of example only, with reference to the accompanying drawings in which: Figure 1 shows a side view of apparatus for plugging a hole according to 5 the invention, in a deflated condition; SFigure 2 shows a top view of the apparatus, in an inflated condition; Figure 3 shows a cross-sectional view of the apparatus illustrated in Figure 2 along the line 3-3; Figure 4 shows a sectional side view of the apparatus of the invention 10 wedged in a borehole; Figure 5 shows a pictorial view of the apparatus in a deflated, folded condition for insertion into a borehole; Figure 6 shows a cross-sectional view, similar to that of Figure 3, of a second embodiment of the apparatus of the invention; Figure 7 shows the apparatus of Figures 6 in a deflated, folded condition for insertion into a borehole; Figure 8 shows a pictorial view of a third embodiment of the apparatus; and Figure 9 shows a side view of the apparatus of Figure 8 in an unfolded condition with part of the outer cover cut away.

IDESCIPTION OF EMBOD)MENTS Figures 1 to 3 of the drawings show. a first embodiment of plug apparatus 5 which comprises an inflatable body 12 having an inner bladder 14 and an outer cover 16.

The inner bladder 14 is gas impervious and is formed from a -relatively soft.

flexible plastics material, such as polyethylene, EVA or plasticised PVC. This bladder 14 is enclosed within -a protective outer cover compri sing first and 10 second generally hexagonal panels 18 and 20 which are stitched together at their edges along a seam 21 to form the outer cover 16. The panels 18 and comprise a tough, relatively non-extensible plastics or fabric material, and serve to protect the inner bladder from abrasion and puncturing in use. In a prototype of the invention, a polyester reinforced PVC material was used for the panels18 and Disposed radially on the upper portion of the inflatable body 12 are elongate -sleeves 28 which are stitched to the panels 18 and 20 so as to have open lower ends 30. Thbe sleeves are shaped and sized to receive rigid rods or spikes 32 in a friction fit so that the rods do not slip out of the sleeves during use. The rods 32 are formed from hard steel rod, reinforced glass fibre, or the like and are sized to project beyond the lower ends 30 of the sleeves 28 as shown. In use, the rods engage the side wall of the borehole 36, thereby -securing the plug apparatus in the borehole. It will be appreciated that the plug apparatus need not include these rods and may be effectively secured in the borehole without them.

At the apex of the upper portion of the inflatable body 12 is an e ye 34 allowing a line (not shown) to be attached to the body for lowering it into a borehole. A length of fuse may be used for this pupose, if desired.

1 In the first embodiment of the invention, a plastic tube 22 is provided which acts as a physical expansion limiting means. The tube 22 is sealed at both ends ad extends internally across the bladder 14 as shown. The tube 22 is also formed from a gas impervious material and carries a built-in inflation means in the form of a small gas canister 24 which is operable from the base of the tube. The canister includes a valve (not shown) which once actuated, allows all the gas to be expelled from the canister. The gas may be any standard aerosol propellant gas such as butane. The tube 22 is configured to expand to a predetermined extent and then rupture, thereby expelling the gas :into the inner bladder. This will allow a user a predetermined amount of time to correctly position the plug in the borehole before the plug expands and is secured in the borehole.

A small aperture 26 in the panel 18 allows a user access to the inner bladder 14. In this way a user can insert his or her hand through the aperture 26 in the outer cover 16 and activate the canister 24 from the base of the tube 22.

Figure 4 shows a borehole 3 6 (not to scale) in which the plug apparatus 10 of the invention has been wedged. To install the plug apparatus, a user activates the canister 24, as described above, and then folds the lateral edges of the apparatus inwardly as shown in Figure 5. A relatively flimsy strap 38 temporarily maintains the apparatus in its folded configuration so that it is relatively easy to lower the body down the borehole 3 6. The strap 3 8 is fixed at one end to one side of the body 12, and at its other end carries adherent material to facilitate quick folding and securing of the body after activation of the gas canister 24. A hook and loop fastening arrangement may be used to secure the free end of the strap 38 to the body 12. Thereafter the apparatus is inserted into and lowered down the borehole 36 to a selected depth with the aid of a fuse 40 connected to the eye 34 on the inflatable body.

As the apparatus is being lowered into the borehole. the canister 24 slowly releases its contents into the tube 22. As described above, since the tube 22 is gas impermeable, the contents of the canister 24 are initially contained within 10 the tube. However, as soon as the pressure in the tube reaches a predetenyined level, the tube ruptures -and expels the pressurized gas into the inner bladder 14. When thig occurs the strap 38 also fails and the inflatable body 12 is distended into its inflated condition in which the rods 32 are brought into engagement with the side wall of the borehole 36i as illustrated in Figure 4.

A charge of explosive material 42 it accurately loc ated in the borehole by the plug apparatus 10, and the fuse -40, which passes through the, explosive material, is used to ignite it.

Since the rods 32 are angled downwardly (see Figure a downward force on the plug apparatus tends to wedge the rods more tightly against the sides of 2 0 -the borehole 36, so that the apparatus resists being forced downwardly in the borehole.

A second embodiment of the plug apparatus is shown in Figures 6 and 7 of the drawings. In this case the plug apparatus 50 has an outer cover 52 and an inner bladder 54 similar to the cover 16 and the bladder 14 of the first embodiment.

Unlike the first embodiment, however, the inner bladder 54 does not include a tube similar to the tube 22- Instead the small gas canister is included directly in the flexible inner bladder 54 itself, and the canister 56 can be activated from outside the bladder 54.

The plug apparatus 50 includes a flexible sleeve 58 of plastics material which acts as a physical expansion limiting means. The sleeve 58 is sized to slip ':over the apparatus once the sides of the apparatus have been folded inwardly as shown in Figure 7. In use, the canister 56 is activated from outside the inner bladder 54, in a mariner similar to that of the first embodiment, and the plug apparatus is thereafter folded and placed within the sleeve 58, as described above. The plug apparatus can now be lowered down the borehole relatively easily. As the canister 56 discharges its contents into the inner bladder 54, the plug apparatus is distended outwardly, However, the sleeve 58 temporarily *~*limits the extent to which the apparatus is distended, thereby allowing the apparatus to be lowered to a selected depth before the inflatable body is fuilly distended. The sleeve 58 is designed to burst or part at a predetermined pressure, in a similar fashion to the tube 22-of-the first embodiment, so as to allow the inflatable body to be fully distended into engagement with the side wall of the borehole when the sleeve faiLs.

A third embodiment of the plug apparatus is shown in Figures 8 and 9 of the 2 0 drawings. In this case the plug apparatus 60 has an outer cover 62 and an inner gas impervious bladder 64. A small gas canister 56 is located in the bottom corner of the inner bladder 64, and the canister 5 6 can be activated from outside the apparatus through a window formed in the outer cover 62.

The plug apparatus includes a flexible sleeve 68 of plastics material which acts as a physical expansion limiting means. The sleeve 68 is sized to slip over the apparatus, as shown in Figure 8, and is taped in a folded position using flexible adhesive tape 72. The sleeve 68 also has a window defined by flaps 70, to allow a user access to the canister. In use, the canister 56 is activated frorm outside the sleeve 68, and the plug apparatus can then be lowered down the borehole relatively easily. As the canister 56 discharges its contents into the inner bladder 64, the body of the plug apparatus is distended outwardly. However, in a similar manner to the second embodiment, the sleeve 68 temporarily limits the extent to which the apparatus is distended, thereby allowing the apparatus to be lowered to a selected depth before the inflatable body is fully distended. The sleeve 68 is designed to burst or part at 10 a predeternxed pressure so as to allow the inflatable body to be fully :distended into engagement -with the side wall of the borehole.

major advantage of the embodiments described above is the fact that the inflatable body is tenmporarily prevented or restrained from distending fully :once the pressurized, gas-filled canister is activated so as to allow the apparatus to be lowered down the borehole relatively easily in a substantially deflated or only partially inflated condition. In this way the full inflation of the inflatable body is delayed until the inflation-restraining means falls once a predetermined pressure is reached in the body, thus allowing for the apparatus to be lowered down the hole to a selected depth before the apparatus becomes 20 wedged in the hole. However, conventional gas canisters can be used and -there is no need for specialized canisters which have a. time delay feature.

It will be appreciated that the physical expansion limiting means need not be an inner tube or outer sleeve, but-may be any other means which effectively delays the full distension of the ping apparatus.

It will also be appreciated that the apparatus can be inflated in different ways.

Instead of the use of a compressed gas canister, gas generating reagents can -1I1 also be used to inflate the body, in a manner known as such.

In tests on prototype versions of the apparatus, pressures in excess of 200 kPa were attained within the inflatable body, although a pressure in the region of 100 to 110 kPa is sufficient to anchor the apparatus firmily in the borehole and to extend the rods or spikes 32 (if used) correctly.

*0 0 .0 6. 0

Claims (7)

1. Apparatus for plugging a hole, the apparatus comprising: an inflatable body; inflation means for inflating the body; and 5 inflation restraining means for temporarily preventing or restraining distension of the body once the inflation S means has been activated so that the body can be lowered into the hole in a substantially deflated or only partially inflated condition, the inflation restraining t10 means being arranged to fail at a predetermined pressure so as to allow the body to become substantially fully distended and consequently wedged within the hole. 0e

2. Apparatus according to claim 1 wherein the inflation means 15 comprises a gas-filled canister located within the inflatable body. Apparatus according to claim 2 wherein the inflation restraining means is a sealed enclosure surrounding the canister and located within the inflatable body.

4. Apparatus according to claim 3 wherein the sealed enclosure is formed from a flexible, gas impervious plastics material. 13 Apparatus according to claim I or 2 wherein the inflation restraining means is a sleeve or strap which is arranged to fit around the inflatable body when the body is in a substantially deflated condition.

6. Apparatus according to any preceding claim wherein the inflatable body is in the form of a bladder comprising a flexible, gas &vow '6impervious plastics material. Apparatus according to any preceding claim fuirther including a protective outer cover to cover the inflatable body.

8- Apparatus according to claim 7 wherein the outer cover defines an aperture to allow a user access to the inflation means. @09. Apparatus acrigto an reeig li further icungat least one wedge member associated with the body and arranged to move from a retracted position to an extended position when the body is inflated, thereby to wedge the body in the hole. :15 10. Apparatus according to claim 9 wherein the at least one wedge member is a plurality of rigid elongate members disposed at an end of the body in the manner of umbrella spokes.

11. Apparatus according to claim 10 wherein each rigid elongate member is located in a sleeve formed onl the body, and each member extends beyond the body in the extended position thereof.

12. Apparatus substantially as herein described with reference to any one of the illustrated embodiments.