Blasting cartridge, blasting apparatus, and blasting method

• US 8,904,938 B2
• Filed: 09/01/2010
• Issued: 12/09/2014
• Est. Priority Date: 09/28/2009
• Status: Active Grant

• Current Assignee: Hitachi Zosen Corporation
• Original Assignee: Hitachi Zosen Corporation
• Inventors: Sasaki, Katsuya, Kitajima, Hideaki, Sakamoto, Ryo, Ohnishi, Takaaki
• Primary Examiner(s): BERGIN, JAMES S
• Application Number:
  US13/498,514
• Publication Number:
  US 20120180684A1
• Time in Patent Office: 1,560 Days
• Field of Search: 102/301, 102/302, 102/322, 102/332, 102/202.5, 102/202.7, 102/202.9, 102/202.11, 102/205, 102/312, 102/313, 102/202
• US Class Current: 102/322
• CPC Class Codes: E04G 23/083 using vaporising wire technique particular applications of blasting techniques F42D3/00
• CPC Class Codes: F42B 3/00 Blasting cartridges, i.e. case and explosive fuse cords, e.g. detonating fuse cords C06C5/00; chemical aspects of detonators, blasting caps or primers C06C7/00
• CPC Class Codes: F42B 3/11 characterised by the material used, e.g. for initiator case or electric leads F42B3/107 takes precedence
• CPC Class Codes: F42B 3/124 characterised by the configuration or material of the bridge F42B3/13 takes precedence
• CPC Class Codes: F42B 3/128 characterised by the composition of the pyrotechnic material
• CPC Class Codes: F42D 3/04 for rock blasting

Abstract

A blasting cartridge includes a generally cylindrical blasting container, a blasting substance filled in the blasting container, a pair of leadwires contained in the blasting container, and a single thin metal wire connected to tip portions of the pair of leadwires. The leadwires and the thin metal wire are positioned within the blasting substance within the blasting container. The blasting substance is nitromethane, and the thin metal wire is formed of tungsten. With an electric discharge impact blasting apparatus, since the thin metal wire has a higher heating value than a copper wire because of its higher resistance and vaporizes at higher temperatures, it is possible to obtain a greater blasting force at lower voltages than with a blasting apparatus using a copper wire.

Claims

1. A blasting cartridge to be used in a blasting apparatus that blasts an object, comprising:

a single self-reactive blasting substance consisting essentially of nitromethane;

a container that contains said blasting substance;

a tungsten wire disposed within said blasting substance, said tungsten wire having a length greater than or equal to 10 mm and less than or equal to 120 mm and a cross-sectional area greater than or equal to 0.03 mm² and less than or equal to 0.13 mm², said tungsten wire being configured to reach the evaporation temperature of tungsten by application of an applied voltage which is greater than or equal to 1500 V and less than or equal to 3000 V to thereby detonate said nitromethane; and

a pair of leadwires whose one ends are connected to both ends of said tungsten wire and whose other ends are connected to a power supply device outside said container.

2. The blasting cartridge according to claim 1, wherein, said tungsten wire is formed of a single metal wire or two or three stranded metal wires.

3. A blasting apparatus for blasting an object, comprising:

a blasting cartridge as defined in claim 1; and

said power supply device, wherein said power supply device comprises;

a capacitor connected to said pair of leadwires;

a power supply part that supplies electric energy to said capacitor; and

a discharge switch that discharges electric energy accumulated in said capacitor to said tungsten wire as said applied voltage through said pair of leadwires.

4. The blasting apparatus according to claim 3, wherein, said tungsten wire is formed of a single metal wire or two or three stranded metal wires.

5. The blasting apparatus according to claim 3, wherein

said capacitor has an electrostatic capacitance greater than or equal to 100 μ

F and less than or equal to 1000 μ

F.

6. A blasting method for blasting an object, comprising the steps of:

a) housing a blasting cartridge comprising self-reactive blasting substance, a tungsten wire and a pair of leadwires as defined in claim 1, in a recessed portion formed in an object, such that said tungsten wire whose both ends are connected to said pair of leadwires is positioned within said blasting substance; and

b) causing said tungsten wire to melt and vaporize by supplying said applied voltage to said pair of leadwires and thereby blasting said object by an impact force caused by said blasting substance.

7. The blasting method according to claim 6, wherein, said tungsten wire is formed of a single metal wire or two or three stranded metal wires.

8. The blasting method according to claim 6, wherein

said capacitor has an electrostatic capacitance greater than or equal to 100 μ

F and less than or equal to 1000 μ

F.