PACKING FOR HOLLOW CHARGES

Abstract

The invention relates to a packing having a top side, a base side and face sides for hollow charges for use in blasting applications in boreholes. In order that fragments are retained in the packing in the event of an unintentional ignition of the hollow charges, the packing withstands the pressure which is generated and permits a dissipation of pressure, it is proposed according to the invention that a) the hollow charges are embedded in a solid material which captures the fragments generated during a detonation of the hollow charges, b) the solid material has pressure relief openings through which the pressure wave of the gas volume generated during a detonation of the hollow charges can escape, c) the solid material is covered with shock-absorbing material on the top side and on the base side of the packing, d) the hollow charges are packed in pairs such that there are always two hollow charges situated opposite the openings, e) the axes of symmetry of the hollow charges are arranged in a plane perpendicular to the top side and base side, and f) the solid material is inserted with the hollow charges and the shock-absorbing material into a cage, preferably a bar-grate-type cage.

Description

FIELD OF THE INVENTION

The invention relates to a packing having a top side, a base side and face sides for hollow charges for use in blasting applications in boreholes.

BACKGROUND OF THE INVENTION

According to the prior art, hollow charges for use in blasting applications in boreholes are packed in pairs in a pack. No protection against fragments is provided. Usually, the whole packing is made of cardboard and, if necessary, a vacuum bag to protect against moisture.

The packing is only suitable to a limited extent for capturing fragments, which are generated in the packing when a hollow charge is initiated. The criteria which are specified by the official 6(d) test are not fulfilled.

As well as the existing criteria of the official 6(a), 6(b) and 6(c) test, the packing must also withstand the “Test 6(d) Unconfined Package Test (UN)” in the “UN Manual of Tests and Criteria”.

The requirements of the official 6(d) Unconfined Package Test dictate that all hazardous effects caused by the reaction of a hollow charge in the packing must be restricted to the packing.

Indications of a hazardous effect outside the packing are:

(a) Denting or perforation of a verification plate under the packing;

(b) A flash or a flame is produced, which ignites a material lying next to the packing, such as a sheet of paper (80±10 g/cm²) at a distance of 25 cm from the packing;

(c) Tearing of the packing and ejection of the contents of the packing, or

(d) An ejected part, which completely punctures the packing (an ejected part or fragment retained or sticking in the wall of the packing is not considered to be hazardous).

BRIEF DESCRIPTION OF THE INVENTION

The invention is based on the object of specifying a packing for hollow charges, which, in the event of an unintentional ignition of the hollow charges, retains the fragments, withstands the pressure generated in the packing and permits a dissipation of pressure.

According to the invention this object is achieved by the characteristics of claim 1, in which a packing is provided having a top side, a base side and face sides for hollow charges for use in blasting applications in boreholes, characterized in that the hollow charges are embedded in a solid material which captures the fragments generated during a detonation of the hollow charges, the solid material has pressure relief openings through which the pressure wave of the gas volume generated during a detonation of the hollow charges can escape, the solid material is covered with shock-absorbing material on the top side and on the base side of the packing, the hollow charges are packed in pairs such that there are always two hollow charges situated opposite the openings, the axes of symmetry of the hollow charges are arranged in a plane perpendicular to the top side and base side, and the solid material is inserted with the hollow charges and the shock-absorbing material into a cage, preferably a bar-grate-type cage.

BRIEF DESCRIPTION OF THE FIGURES

A more particular description of the invention briefly described above will be rendered by reference to specific embodiments thereof that are illustrated in the appended drawings in which:

FIG. 1 is a perspective view of a packing according to an embodiment of the invention;

FIG. 2 is an end view of the packing of FIG. 1 according to an embodiment of the invention; and

FIG. 3 is a perspective end view of the packing of FIG. 2 according to an embodiment of the invention.

DETAILED DESCRIPTION

In an embodiment of the invention, a packing is provided having a top side, a base side and face sides for hollow charges for use in blasting applications in boreholes, characterized in that the hollow charges are embedded in a solid material which captures the fragments generated during a detonation of the hollow charges, the solid material has pressure relief openings through which the pressure wave of the gas volume generated during a detonation of the hollow charges can escape, the solid material is covered with shock-absorbing material on the top side and on the base side of the packing, the hollow charges are packed in pairs such that there are always two hollow charges situated opposite the openings, the axes of symmetry of the hollow charges are arranged in a plane perpendicular to the top side and base side, and the solid material is inserted with the hollow charges and the shock-absorbing material into a cage, preferably a bar-grate-type cage.

According to the invention this object is achieved because

a) the hollow charges are embedded in a solid material which captures the fragments generated during a detonation of the hollow charges,

b) the solid material has pressure relief openings through which the pressure wave of the gas volume generated during a detonation of the hollow charges can escape,

c) the solid material is covered with shock-absorbing material on the top side and on the base side of the packing,

d) the hollow charges are packed in pairs such that there are always two hollow charges situated opposite the openings,

e) the axes of symmetry of the hollow charges are arranged in a plane perpendicular to the top side and base side, and

f) the solid material is inserted with the hollow charges and the shock-absorbing material into a cage, preferably a bar-grate-type cage,

a packing for hollow charges, which, in the event of an unintentional ignition of the hollow charges, retains the fragments, withstands the pressure generated in the packing and permits a dissipation of pressure, is created.

The solid material ensures that fragments are captured. The pressure relief openings in the solid material allow the gas generated during a detonation of the hollow charges to escape. Axial forces, which are generated when a hollow charge is initiated (hollow charges can also be perforators), are absorbed by the shock-absorbing material. The shock-absorbing material can be constructed in a sandwich design with materials such as wood, metal and plastic for example. The solid material is covered with the shock-absorbing material on its top side and base side and the shock-absorbing material borders on the solid material here.

The feature that the axes of symmetry of the hollow charges are arranged in a plane perpendicular to the top and base side means that the axes of symmetry of the hollow charges are arranged parallel to the axis of symmetry of the packing. As a result, when a hollow charge is initiated, the hollow charge jet is directed onto the shock-absorbing material, which borders on the solid material at the top side and base side. The hollow charge jet must not expand in the direction of the face sides of the packing. The pressure relief openings are arranged perpendicular to the axes of symmetry of the hollow charges so that the hollow charge jet does not expand in the direction of the pressure relief openings. In this respect, the terms top side and base side are interchangeable. All that is important is that the top side and base side extend perpendicular to the axis of symmetry of the packing and perpendicular to the axes of symmetry of the hollow charges.

The hollow charges are packed in pairs such that there are always two hollow charges situated opposite the openings. This has the advantage that, when one hollow charge is detonated, the other hollow charge is destroyed. Because the axes of symmetry of the hollow charges are arranged in a plane perpendicular to the top and base side, the hollow charge jets generated during a detonation are directed onto the shock-absorbing material and are dissipated there.

According to the invention, the solid material is inserted with the hollow charges and the shock-absorbing material into a cage, preferably a bar-grate-type cage. This captures larger ejected pieces of the inner packing and the hollow charges and, at the same time, allows the pressure wave through.

The solid material, which captures the fragments, and the pressure relief openings are arranged with respect to one another such that, when a hollow charge is initiated, the fragments generated thereby are captured in the solid material at the latest by the shock-absorbing material and do not leave the packing.

The solid material is preferably wood or plastic.

In a preferred embodiment, the solid material consists of three sandwich-like layers arranged one above the other, and a gap, which forms the pressure relief openings, is arranged between the layers. The gap is preferably arranged in a plane perpendicular to the top and base side. The gas escaping during a detonation therefore leaves the cage at the face sides.

Preferably, the top and bottom layers of the solid material are designed in the form of a sheet and have closed surfaces.

Advantageously, the shock-absorbing material is constructed in sandwich design with preferably wood, metal or plastic. This enables it to be constructed extremely solidly.

Preferably, the cage is inserted in an outer packing, preferably made of cardboard.

In a preferred embodiment, the cage, the solid material and the shock-absorbing material are designed with a cuboid shape having a base side, a top side and four face sides. This enables the hollow charges to be easily packed.

Advantageously, the cage is reinforced on its base side and its top side with a steel plate. This additionally reinforces the cage.

For easy filling, one of the face sides of the cage is in the form of a door and the door is connected to the base side by means of hinges.

The hollow charges can also be perforators.

The funnels in the hollow charges can be filled with a material to prevent the development of the hollow charge jet on initiation.

The invention is explained further below with reference to three figures.

FIG. 1 shows an empty cuboid-shaped cage 1, designed as a bar-grate-type cage, having a base side 9, a top side 8 and four face sides 3a, 3b, 3c, 3d. The cage 1 is reinforced on its base side 9 and its top side 8 with a steel plate 2. One of the face sides 3a can be opened to enable the cage 1 to be loaded. Here, the face side 3a is designed as a door 11 and connected to the base side 9 by means of hinges 4.

FIG. 2 shows the cage 1 shown in FIG. 1 with open face side 3a or door 11 and filled with a solid material 5a, 5b, 5c, in this case wood, in which the hollow charges 12 are inserted. The axis of symmetry 14 of the packing is denoted by the reference 14. In this embodiment, the solid material 5a, 5b, 5c comprises three layers 5a, 5b, 5c which are arranged one above the other in the form of a sandwich. A gap, which forms the pressure relief openings 10 and through which a dissipation of pressure can take place, is provided between the individual layers 5a, 5b, 5c. The two top 5a and bottom layers 5c of the solid material are designed in the form of a sheet and have closed surfaces. These two layers 5a, 5c are covered with a shock-absorbing material 6. The shock-absorbing material 6 can be constructed in a sandwich design with materials such as wood, metal and plastic for example.

FIG. 3 shows the packing 13 with the filled cage 1 according to FIG. 2 inserted in a cardboard box. This box forms the outer packing 7.

Claims

1. A packing having a top side, a base side and face sides for hollow charges for use in blasting applications in boreholes, comprising: a) the hollow charges are embedded in a solid material which captures the fragments generated during a detonation of the hollow charges,b) the solid material has pressure relief openings through which the pressure wave of the gas volume generated during a detonation of the hollow charges can escape,c) the solid material is covered with shock-absorbing material on the top side and on the base side of the packing,d) the hollow charges are packed in pairs such that there are always two hollow charges situated opposite the openings,e) the axes of symmetry of the hollow charges are arranged in a plane perpendicular to the top side and base side, andf) the solid material is inserted with the hollow charges and the shock-absorbing material into a cage, preferably a bar-grate-type cage.

2. The packing as claimed in claim 1, wherein the solid material is wood or plastic.

3. The packing as claimed in claim 1, wherein the solid material comprises three sandwich-like layers arranged one above the other, and a gap, which forms the pressure relief openings, is arranged between the layers.

4. The packing as claimed in claim 3, wherein a top and bottom layer of the solid material are designed in a form of a sheet and have closed surfaces.

5. The packing as claimed in claim 1, characterized in that the shock-absorbing material is constructed in a sandwich design with preferably wood, metal or plastic.

6. The packing as claimed in claim 1, wherein the cage, is inserted in an outer packing, made of cardboard.

7. The packing as claimed in claim 1, wherein the cage, the solid material and the shock-absorbing material are designed with a cuboid shape of the base side, top side and face sides.

8. The packing as claimed in claim 1, wherein the cage is reinforced on its base side and its top side with a steel plate.

9. The packing as claimed in claim 1, wherein one of the face sides of the cage is in the form of a door and the door is connected to the base side by means of hinges.

10. The packing as claimed in claim 1, wherein the hollow charges are perforators.