WO2002097360A1

WO2002097360A1 - A cartridge

Info

Publication number: WO2002097360A1
Application number: PCT/IB2002/001924
Authority: WO
Inventors: Mihailo Gavrilovic; Jeffrey William Branson
Original assignee: Individual
Current assignee: Individual
Priority date: 2001-05-31
Filing date: 2002-05-31
Publication date: 2002-12-05
Anticipated expiration: 2003-11-30

Abstract

A cartridge for insertion into a hole formed in a body of a hard material is provided and comprises at least two charges of an energetic substance separated by a plug of a stemming material.

Description

A CARTRIDGE

FIELD OF THE INVENTION

This invention relates to a cartridge, more particularly, but not exclusively, to a cartridge for use in excavating hard material such as rock and concrete.

BACKGROUND TO THE INVENTION

When using an energetic substance, such as a propellant or explosive, to excavate hard material such as rock or concrete it can be necessary to separate charges of the energetic substance by a plug of a stemming material. Such a configuration of charges is sometimes referred to as a "decked charge".

At present, decked charging is achieved by inserting a charge of an energetic substance into a hole formed in a surface of a hard material, inserting a plug of stemming material, inserting the next charge and then a further plug of stemming material. This can be a laborious and time-consuming task which in turn reduces productivity.

OBJECT OF THE INVENTION

It is an object of this invention to provide a cartridge which will at least partially alleviate some of the abovementioned problems.

SUMMARY OF THE INVENTION

In accordance with this invention there is provided a cartridge for insertion into a hole formed in a body of a hard material comprising at least two charges of an energetic substance separated by a plug of a stemming material. Further features of the invention provide for the cartridge to be elongate with a first end for insertion into a hole with a charge of an energetic substance at or near the first end and a plug of stemming material at or near the opposite end; for each charge to have an initiation device associated therewith; and for a delay element to be optionally associated with either of the charges.

One aspect of the invention provides for each charge of an energetic substance to be contained in a closed receptacle, preferably a water impervious receptacle; for the charges and stemming material to be secured in sequence in a tube; and for the tube to be made of a rigid or a flexible material.

According to a second aspect of the invention there is provided for each of the charges and stemming material to be contained in an elongate receptacle with the receptacles being secured end to end.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be described, by way of example only, with reference to the drawings in which:

Figure 1 is a part sectional side elevation of a first embodiment of a cartridge in a hole; Figure 2 is an exploded perspective view of a second embodiment of a cartridge; and

Figure 3 is a part sectional side elevation of a third embodiment of a cartridge.

DETAILED DESCRIPTION OF THE DRAWINGS

A cartridge (1 ) is shown in Figure 1 inserted into a hole (2) formed in a hard material body (3), in this embodiment rock. The cartridge (1 ) includes a pair of charges (10, 11) of an energetic substance, in this embodiment a mixture of a propellant and ammonium nitrate, separated by a plug of stemming material (12). The charge (11 ) separates the plug (12) from a further plug of stemming material (13). In this embodiment the stemming material is particulate.

The charges (10, 11 ) are each contained in a water impervious plastics receptacle (15, 16) while the stemming material plugs (12, 13) are each contained in a thin-walled tube (18, 19) made of a paper or a plastics material. An initiating device (not shown), in this embodiment an electric igniter, is inserted into each of the charges (10, 11 ).

The charges (10, 11 ) and plugs (12, 13) are enclosed in a plastics sheath (20) with the electrical leads (22) from the initiators extending from the end of the sheath (20) adjacent plug (13). It is preferable that the sheath (20) be made of a thin material to enable the stemming material to rupture it to so make contact with the sides of the hole (2) when charges (10, 11) are initiated.

The cartridge (1) in effect provides a decked charge which is inserted into the hole (2) with the charge (10) adjacent the end of the hole (2). It is envisaged that the cartridge (1 ) will be less time-consuming to insert into a hole than conventional methods and will be easier to transport and handle than the components separately.

It will be appreciated, however, the many other embodiments of a cartridge exist which fall within the scope of the invention. For example, referring to Figure 2, a cartridge (30) can be formed by securing alternate tubes containing energetic material (32,33) and stemming material (34, 35) end to end. In the embodiment shown the tubes (32,33) containing energetic material provide a fiction that in sockets provided at each end of the tubes (34, 35) containing stemming material. Complementary engaging formations may, however, also be provided.

One end (36,37) of each tube (32,33) is conical which, it is envisaged, will cause outward displacement of the stemming material in the attached tubes (34, 35) on initiation of the charges. This in turn should assist the stemming material in resisting expulsion from the hole.

The charges are initiated using shock tube (38) operated igniters (not shown). The shock tube (38) is a press fit in a groove (39) which extends along the respective tubes.

A cylindrical plug (40) which is diagonally split (41 ) along its length to form a pair of wedges is secured at one end (42) in the free end of the tube (35). Once the cartridge (30) has been inserted into a hole in the free end (43) of the plug (40) will project from the opening and hammering on the end (43) will cause expansion of the plug (40) in known fashion. The plug (40) will thus further resist expulsion of the cartridge (30) from a hole upon initiation of the charges (32,33).

As shown in Figure 3, a cartridge (50) can be formed from a tube (51 ) which is closed at one end (52). A charge (54) of an explosive is inserted into the tube (51 ) to abut the closed end (52). Particulate stemming material (55) is then poured into the tube (51 ) to form a plug and then a second explosive charge (56) inserted into the (51 ). A further plug of stemming material (57) is formed over the second charge (56) to fill the tube (51 ) and the open end of the tube (51) then closed with a cover (59).

The charges (54, 56) are initiated by electrical detonators (not shown) and a time delay element (60) is provided to delay initiation of the second charge (56).

It will be appreciated that any suitable energetic substance, or combination of substances, can be used as well as any suitable stemming including gels or clay-like materials. Furthermore, the cartridge and, where provided, receptacles for the stemming material can be provided with lines of weakness to allow easy rupture upon initiation of the charges or even during insertion into a hole. Also, any suitable means of initiating the charges can be used including non-electric, electronic and detonating cord operated devices, and any suitable delay element can be associated with the charges.

Claims

1. A cartridge for insertion into a hole formed in a body of a hard material comprising at least two charges of an energetic substance separated by a plug of a stemming material.

2. A cartridge as claimed in claim 1 which is elongate with a first end for insertion into a hole and with a charge of an energetic substance at or near the first end and a further plug of stemming material at or near the opposite end.

3. A cartridge as claimed in claim 1 or claim 2 in which each charge has an initiation device associated therewith.

4. A cartridge as claimed in any one of the preceding claims in which a delay element is associated with at least one of the charges.

5. A cartridge as claimed in any one of the preceding claims in which each charge of an energetic substance is contained in a closed receptacle.

6. A cartridge as claimed in claim 5 in which each receptacle is water impervious.

7. A cartridge as claimed in any one of the preceding claims in which the charges and stemming material are secured in sequence in a tube.

8. A cartridge as claimed in claim 7 in which the tube is rigid.

9. A cartridge as claimed in claim 7 in which the tube is made of a flexible material.

10. A cartridge as claimed in any one of claims 1 to 4 in which each of the charges and stemming material is contained in a receptacle with the receptacles being secured end to end.

11. A cartridge substantially as herein described and as illustrated with reference to Figure 1 or Figure 2 or Figure 3.