Nippon Oil Fats Co., Ltd.

Kajima Corporation

Nippon Oil and Fats Company, Limited and Kajima Corporation

Koichi Kurokawa

Katsuhide Hattori

Yoji Tasaki

Takeo Ueda

Koji Edamura

Mikio Takano

Toshikazu Miyajima

Motoyuki Amano

Katsura Ogasawara

Toshifumi Sato

Tomoyuki Amano

Kenji Hashimoto

Akihiro Tanaka

Yoshiro Osumi

A wireless detonator is disclosed that includes an antenna for receiving microwaves, a detonator provided with a heating element, and a transmission circuit. The heating element in the detonator is heated by the energy of the microwaves. The transmission circuit transmits the microwave energy from the antenna directly to the heating element. The antenna has a relative gain of 0 to 20 dB in the frequency band of the microwaves. The absolute value of the reactance component in the radiation impedance of the antenna is at most 50% of the pure resistance component of that impedance. The absolute value of the reactance component in the impedance of the heating element is at most 50% of the pure resistance component of that impedance. The pure resistance components of the radiation impedance of the antenna and of the impedance of the heating element are in a range of 70 to 130% of the characteristic impedance of the transmission circuit.

Wireless detonator

An excellent water in oil type emulsion explosive having both of a superior handling property and a good aging initiating sensitivity at low temperatures and at small calibers, is provided by using a specific low molecular weight polyethylene as the carbonaceous fuel in the emulsion explosive.

Water in oil type emulsion explosive

Thermostability, age stability, and ignition property at low temperatures of a W/O type emulsion explosive are remarkably improved by incorporating a chelating agent in the W/O type emulsion explosive.

Water-in-oil type emulsion explosive with chelating agent

A laser beam-detonatable blasting cap containing secondary explosives charged therein in the upper and lower portions, wherein the explosive charged in the upper portion contains a laser beam-absorbing black material and is contacted with an optical fiber at the top. The loading density of the explosive charged in the lower portion is higher than that of the explosive charged in the higher portion, and only the side of the explosive charged in the upper portion is surrounded with a restraining wall. The blasting cap can be easily and surely detonated by a laser beam having a low peak output power generated by means of a pulse-oscillation system without using Q-switching or a continous oscillation system.

Laser beam-detonatable blasting cap

An apparatus for electrically blasting a number of electric detonators arranged at a plurality of working faces, including a single controller having a power source unit for supplying a D.C. voltage and a plurality of ignition control units for selectively applying the D.C. voltage; a plurality of oscillators each arranged near respective working faces, the number of the oscillators corresponding to that of the ignition control units, each oscillator being energized with the D.C. voltage to generate a high frequency current and being connected to respective ignition control units via an electric wire bundle; and a plurality of lead wires each connected to outputs of respective oscillators. Loop-like leg wires of electric detonators are electro-magnetically coupled with the lead wires with the aid of transformer magnetic cores.

Method of electrically blasting a plurality of detonators and electric

A loop portion of a bus wire connected to an electric blasting device is passed through a first magnetic core together with a first loop-like wire, and the first loop-like wire is further passed through a second magnetic core provided in a detonator. The detonator includes a second loop-like wire which is passed through the second magnetic core, an electric bridge connected to the second loop-like wire and a fuse head provided around the electric bridge. When a pulsatory high frequency current is supplied to the bus wire, high frequency currents are induced in the first and second loop-like wires by electromagnetic induction. Then the current flows through the electric bridge of the detonator to fire the primer explosive.

Growing community of inventors

Chita, Japan

Koichi Kurokawa