AU2008100509A4

AU2008100509A4 - Blast hole plug and actuator therefor

Info

Publication number: AU2008100509A4
Application number: AU2008100509A
Authority: AU
Inventors: Koen Alixe Mauritz Dhooge
Original assignee: Riplog Pty Ltd
Current assignee: RIPLOG Pty Ltd
Priority date: 2008-06-03
Filing date: 2008-06-03
Publication date: 2008-07-03
Anticipated expiration: 2016-06-03

Description

P/00/011 Regulation 3.2

AUSTRALIA

Patents Act 1990 COMPLETE SPECIFICATION INNOVATION PATENT Invention Title: Blast hole plug and actuator therefor The following statement is a full description of this invention, including the best method of performing it known to us: 00 SBLAST HOLE PLUG AND ACTUATOR THEREFOR c BACKGROUND OF THE INVENTION O THIS invention relates to a blast hole plug and to an actuator forming part of the blast hole plug.

Blast hole plugs are known which comprise an inflatable plastic body in _which is contained a canister of gas. A reinforcing sleeve surrounds the 00 inflatable body.

To operate the blast hole plug, an actuator on the gas canister is operated by a user, which starts the release of gas from the canister and the inflation of the device. The device is then lowered into a blast hole to a desired position. As the blast hole plug inflates, it lodges in the blast hole and effectively provides a deck for stemming and explosives.

An example of a blast hole plug of this kind is described in International Patent Publication WO 01/04565.

Any reference in this specification to the prior art does not constitute an admission that such prior art was well-known or forms part of the common general knowledge in any jurisdiction.

SUMMARY OF THE INVENTION According to the invention there is provided a blast hole plug comprising an inflatable body; a container of pressurized gas in the inflatable body; and an actuator associated with the container of pressurized gas, the actuator comprising a cap attachable to the container of pressurized gas, an actuator member movable from a first, non-active position to a second, release position to release gas from the container, and a latch mechanism for retaining the actuator member in said release position, the actuator being formed from acetal plastics material.

Doc ID 005445388 00 ;ZFurther according to the invention there is provided an actuator for a blast M hole plug which comprises an inflatable body and a container of pressurized gas in the inflatable body, the actuator comprising a cap which is attachable to a container of pressurized gas, an actuator member I movable from a first, non-active position to a second, release position to Srelease gas from the container, and a latch mechanism for retaining the actuator member in said release position, the actuator being formed from 00 an acetal plastics material.

The cap of the actuator may define a mounting ring attachable to a rim at an upper end of the container of pressurized gas.

The actuator member may define a tapered bore in which a stem of the container of pressurized gas can be received in a gas-tight manner, and a nozzle through which the contents of the container can be expelled.

The cap, the actuator member and the latch mechanism are preferably formed as an integral moulded article.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 Is a perspective view of a blast hole plug in an un-inflated configuration thereof; Figure 2 is a perspective view of the blast hole plug of Figure 1 with a pressure tube thereof removed, showing how the blast hole plug is folded; Figure 3 is a perspective view of the blast hole plug in its fully inflated configuration; Doc ID 005445388 00 Figure 4 is a cross sectional view on the line 4-4 in Figure 3, showing ;Za gas canister within the inflatable body of the blast hole Cc plug; Figure 5 is a first pictorial view from above of an actuator for a Scontainer of pressurized gas within the body of the blast hole Splug; 00 Figure 6 is a perspective view from below of the actuator of Figure Figure 7 is a sectional side view of the actuator mounted on a canister of pressurized gas, prior to use thereof; Figure 8 is a similar view to that of Figure 7, showing the actuator latched into a release position thereof; Figure 9 is a cross sectional side view of a blast hole plug with the blast hole plug of the invention; and Figure 10 is a cross sectional plan view on the line 10-10 in Figure 9.

DESCRIPTION OF A PREFERRED EMBODIMENT The blast hole plug shown in Figures 1 to 4 is similar to that described in WO 01/04565. The blast hole plug 10 includes an inflatable plastic bladder 12, a paper sleeve 14, and a plastic sleeve 16 which are all folded up and contained within a plastic bag 18.

The inflatable bladder 12 consists of an inner weldable material 20 such as polyethylene and an outer gas barrier 22 made of nylon or an acrylic material. An aerosol gas canister 24 containing a non-flammable mixture of a gas and a solvent is located within the bladder 12. (In Figure 4 the solvent 26 is shown within the inflated blast hole plug.) Doc ID 005445388 00

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;The paper sleeve 14 consists of three layers 28 of paper. Each layer is 100 microns thick and is not treated with a non-flammable or flame resistant substance. The prime function of the paper sleeve 14 is that of an insulator.

It acts as a heat barrier which prevents the heat of a blast from melting the plastic bladder. If the plastic bladder melts it will deflate and the blast plug Swill not be able to contain the blast within a blast hole 32. Thus it can be Sappreciated that the heat barrier could be made of other suitable materials 00

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such as aluminium foil, which is also flexible and which can reflect the heat 0 of the blast away from the plastic bladder. Thus the heat barrier must not melt, or must at least have a substantially higher melting point than the plastic bladder 12 and the plastic sleeve 16, so that it protects the plastic bladder 12 from the heat of the blast and prevents the plastic bladder from being melted by the heat of the blast.

The plastic sleeve 16 is made of woven polypropylene. The function of the plastic sleeve 16 is to contain the plastic bladder 12 against over-expansion if the paper sleeve 14 ruptures. The paper sleeve 14 can rupture if water dissolves the adhesive which forms a seam 30 between two overlapping ends of the paper. In situations where water is not present, the plastic sleeve 16 is not necessary since the paper sleeve 14 is strong enough by itself to contain the plastic bladder 12, and to prevent the plastic bladder 12 from being punctured by sharp portions of the sidewall of the blast hole 32.

The plastic bag 18, the plastic sleeve 16 and the paper sleeve 14 have apertures 32 through which the gas canister 24 can be seen and activated.

The function of the plastic bag 18, other than to store the folded plastic bladder 12, paper sleeve 14 and plastic sleeve 16, is to restrict the size of the bladder 12 for a limited period of time whilst it is being inflated. This limited period of time provides a user with sufficient time to activate the gas canister 24 and to insert the blast hole plug 10 into a blast hole 32 before the plastic bag 18 ruptures and the bladder 12 becomes too large to insert into the blast hole 32.

Doc ID 005445388 00 SA charge of explosive 34 and a fuse 36 are first placed into the blast hole ;Z32. The blast plug 10 is then inserted into the blast hole 32 after the Mc, aerosol canister has been activated. Once the blast hole plug 10 has inflated sufficiently to plug the blast hole 32, stemming 38 is poured into the blast hole 32 onto the top of the blast plug SFigures 5 to 8 show an improved actuator 50 which forms part of the blast 0hole plug of the present invention. The actuator is intended to be clipped 00 Sfirmly onto a ridge or rim 48 at the upper end of the gas canister 24, as best C shown in Figures 7 and 8. The actuator 50 comprises a body defining a mounting ring 52 with an inwardly extending lip 54. The lip 54 has an inclined surface 56 which allows the actuator to be pushed over the rim 48 and maintained in position by the lip on the top of the canister. Formed integrally with the mounting ring 52 is an actuator member comprising an upstanding central portion 58, an operating tab 60 extending radially outwardly beyond the ring 52, and a bridge portion 62 joining the tab to the mounting ring 52.

As best shown in the sectional views of Figures 7 and 8, the upstanding central portion 58 of the actuator has a stepped bore 64 which is formed with a slight taper for engaging the stem 74 of the gas canister 24 with a gas-tight seal. The bore 64 has a widened mouth portion 66. At the extreme inner end of the bore 64 is a nozzle 68 through which the contents of the gas canister are expelled in use.

As best seen in Figures 6, 7 and 8, a clip or latch member 70 is formed integrally with the actuating tab 60 and extends below the tab. On its outer edge, the catch has a chamfer allowing it to ride over the inner edge of a complemental catch formation 72 formed at an edge of an opening in the mounting ring 52.

When the tab 60 is depressed as indicated by the arrow in Figure 8, the catch members 70 and 22 ride over one another and lock the actuator Doc ID 005445388 00 (Ni Smember in its depressed position, operating the gas canister and causing Zits contents to be expelled via the nozzle 68. The tapered construction of Mc, the bore 64 ensures a gas-tight fit over the stem 74 of the gas canister, so that gas does not leak from the actuator in use, but is expelled only from the nozzle 68.

SThe actuator is molded from acetal plastics material, which maintains its 0shape and physical properties over a wide temperature range, and helps to 00 Sensure that gas does not leak from the joint between the stem 74 and the C(N bore of the actuator member in use.

The blast hole plug 10 performs two functions. Firstly, it contains the blast within the blast hole 32. In this regard the blast hole plug 10 provides sufficient time for the gas pressure to build up in the air gap 40 in the blast hole 32 before the plug 10 is shattered by the blast. Secondly, the blast hole plug 10 acts as a deck upon which the stemming 38 is supported.

Doc ID 005445388

Claims

1. A blast hole plug comprising an inflatable body; a container of O pressurized gas in the inflatable body; and an actuator associated with the container of pressurized gas, the actuator comprising a cap Oattachable to the container of pressurized gas, an actuator member Omovable from a first, non-active position to a second, release position to release gas from the container, and a latch mechanism 00 OO for retaining the actuator member in said release position, the Oactuator being formed from an acetal plastics material.

2. An actuator for a blast hole plug which comprises an inflatable body and a container of pressurized gas in the inflatable body, the actuator comprising a cap which is attachable to a container of pressurized gas, an actuator member movable from a first, non- active position to a second, release position to release gas from the container, and a latch mechanism for retaining the actuator member in said release position, the actuator being formed from an acetal plastics material.

3. An actuator according to claim 2 wherein the cap defines a mounting ring attachable to a rim at an upper end of the container of pressurized gas.

4. An actuator according to claim 2 or claim 3 wherein the actuator member defines a tapered bore in which a stem of the container of pressurized gas can be received in a gas-tight manner, and a nozzle through which the contents of the container can be expelled. An actuator according to any one of claims 2 to 4 wherein the cap, the actuator member and the latch mechanism are formed as an integral moulded article. Doc ID 005445388