US2644117A - Blasting machine - Google Patents

Description

June 30, 1953 R. A. SCHMITT ETAL 2,644,117

BLASTING MACHINE Filed July 2, 1952 INVENTORS R T A. SCHMITT BY flfl d ATTORNEYS Patentecl June 30, 1953 UNITED STATES PATENT GFFEQE 2,644,117 BLAS'IING MACHINE Application July 2,1952, Serial No. 296,872

The present invention relates'to a blasting machine. More particularly, the present invention relates to a blasting machine for use with a non-- explosive blasting cartridge of the pressure-reslstant tube type wherein the gas-producing charge consists of a chemical composition which is initiated by the application of heat.

In co-pending application Serial Number 174,818, filed July 20, 1950, by Davis, Glogau, Loving, and Swed, a blasting assembly is described wherein a reusable pressure-resistant tube contains a prepackaged charge of ammonium nitrate sition, and that the current must be sustained for several seconds. The burning through of the ribbon interrupts the current, thus reducing the likelihood of sparks occurring outside of the blasting cartridge.

It is an object of the present invention to provide a device for the safe initiation of the blasting cartridges described above. A further object is to provide a portable controller for the safe application of current to initiate a blasting cartridge. Additional objects will become apparent as the invention is further described.

We have found that the foregoing objects may be attained when we provide a blasting controller adapted to provide a current of from '2 to 11 amperes as long as the starter ribbon is effective, and then to discontinue the current to the blasting cartridge.

In order to more fully describe the present invention, reference is made to the accompanying drawing which represents a diagram of a circuit adapted to produce the desired results.

In the drawings, l is a power source, for example, a 36 volt wet storage battery, 2 is a fuse, e. g., 20 amperes, 3 is a snap-toggle type double-pole switch and 4 is a dual-coil current regulating relay adapted to be energized by a current in excess of 13 amperes, mechanically latching in the energized position, and electrically resetting by the second coil. 5 is a set of breaker points actuated by relay 4 and B is a pushbutton switch 5Claims. ((21. 31780) in series with the resetting coil of relay 4. l is a condenser, preferably an electrolytic type, 8 is a snap-toggle double throw switch'which connects the condenser I 'circuit'to either contact 9 or contact ID. i! is a dual coil relay, one coil in series with the condenser circuit adapted to energize the relay momentarily, and a second coil in series with the firing circuit adapted to maintain the relay in the actuated position while a current of at least 2 amperes fiows therethrough. l2 and I3 are breaker points actuated by relay i I. I4 is a resistance element, [5 is an indicator light, and I6 is an outlet receptacle.

In operation, one or more blasting cartridges are connected to the present device at receptacle 1 6. Main line switch 3 is then closed, and pushbutton 6 depressed to insure the closing of points 5 by relay 4. Snap-toggle switch 8 is thrown to connect with contact 9, thus completing the circuit from the power source l to the condenser 1, the latter being charged thereby. When switch 8 is reversed, i. e., connected with contact [8, the condenser T discharges through relay H, which is thus momentarily actuated, thereby closing breaker points [2 and [3. This completes a circuit from power source I through relay H to receptacle [6, and if at least 2 amperes current is flowing, relay ll remains actuated, and the blasting cartridge starter ribbons receive the required electrical current. As soon as the starter ribbon is burned through, the current is interrupted and relay II is deenergized, thus opening the circuit. In the event a short occurs so that the current exceeds 13 amperes, relay 4 is energized, thereby opening the circuit. Indicator light I5 will permit the operator to visually check whether the circuit was completed and continued for a sufficient length of time for the initiation of the charge.

The essential features of the present invention reside in a relay in series with a firing circuit to disconnect the power source from the lead wires as soon as the starter ribbon is parted, the use of a condenser circuit to momentarily energize the relay to provide a closed firing circuit, and relay means for limiting the current to a predetermined maximum value. Preferably, the device also contains an indicator light to visually apprise the operator of the operation of the firing circuit, and a means for electrically resetting the current limiting relay in the event it has become energized. The fuse is present merely to protect the assembly in the event of a short circuit. It may also be desirable to connect an ammeter in series with the firing circuit so that the operarent value between 2 and 11 amperes is deliverable to the blasting cartridge.

While the invention has been fully described with reference to the specific'embodiment illustrated in the drawing, it will be understood that variations in design and construction may be 7 made without departure from the spirit of the invention. Therefore, we intend to be limited only by the following claims:

We claim:

1. A blasting machine comprising a firing circuit, means for connecting said firing circuit toa source of electrical energy, a condenser circuit containing a condensena dual coil relay having one coil in series with said firing circuit adjusted to maintain said relay in an energized condition when a current of a predetermined magnitude flows in said firing circuit, and a second coil adjusted to momentarily actuate said relay from the energy of a condenser discharge, switch'me'ans which in one position connects the condenser circuit in parallel with the firing circuit and in the second position in series with the second coil of said relay, circuit closing elements connected in series with said firing circuit and actuated by said relay, and electrical means for opening said firing circuit if the current exceeds a pre determined magnitude.

2. A blasting machine comprising a firing circuit, a battery, manual switch means for connecting said battery with said firing circuit, a condenser circuit containing a condenser, a dualcoil relay having one coil in series with said firing 4 1 mined'magnitude flows therethrough and a second coil adjusted to momentarily actuate said relay from the energy of a condenser charge, switch means which in one position connects the said condenser circuit in series with said battery and in'the'secondposition in'serie's with said second coil of said relay, circuit closing elements connected in series with said firing circuit and actuated by said relay, and electrical means for opening said firing circuit if the current exceeds a predetermined magnitude.

- 3. A blasting machine comprising a firing circuit, a battery, switch means for connecting said battery in series with said firing circuit, a condenser circuit containing a condenser, a dual coil relay having one coil in series with said firing circuit adjusted to maintain said relay in an energized condition when a current of predetermined magnitude flows therethrough, and a second coil adjusted to momentarily actuate said relay from the energy of a condenser discharge,

"switch means which in one position connects the condenser circuit in series with-said battery, and in the second position in series with said second coil of said relay; circuit closing elements con nected in series with said firing'circuit and actu' ated by said relay, and a second relay having a coil in series with said firing circuit adjusted to energize said relay at a predetermined current higher in magnitude than that required to maintain the first relay in an energized condition, said second relay actuating circuit-breaking elements connected in series with said firing circuit.

circuit adjusted to maintain saidrelay in an 4. A blasting machine as claimed'in claim 3, wherein the first relay will be maintained in-an energized condition by a current of at least 2' amperes, and said second relay will be energized by a current in excess of 13 amperes.

5. A blasting machine as claimed in claim 3, wherein said second relay is of the mechanically latching, electrically resetting'type.

ROBERT A. SGHMITT. JAMES P.-SWED. CHARLES =P. WILLIAMS.

N 0 references cited.

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