Nippon Oil Fats Co., Ltd.

Takeo Ueda

Koichi Kurokawa

Masashi Nakano

Yoshiro Osumi

Yoshiro Ohsumi

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.

Method of electrically blasting detonator and cordless detonator for use

A remote blasting system for exploding a number of explosives in a multiple-step manner including an oscillating unit for radiating an electromagnetic wave due to which A.C. currents are induced in receiving units some of which are directly connected to detonators and the remaining receiving units being connected to detonators via at least one switching unit which includes a switch and an actuating member for driving the switch. At the end of first excitation, the switch is closed and at the end of second excitation the detonator is blasted via the closed switch.

Remote blasting system for effecting multiple-step explosion and

A number of detonating primers are electrically blasted by supplying a high frequency current through a bus wire formed by a pair of parallel conductors connected to each other at distal ends and having a constant impedance with which bus wire loops connected to the detonating primers via leg wires are electromagnetically coupled via a number of magnetic cores having slits formed therein. At first, one or more loops are inserted into respective magnetic core through the slit and one of the parallel conductors is also inserted into the magnetic core through the slit. When the high frequency current having a frequency from 100 KHz to 1 MHz is passed through the conductors of bus wire in opposite directions, there is induce electromagnetically secondary high frequency currents in respective loops, which are supplied to respective detonating primers for explosion.

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Aichi, Japan

Takeo Ueda