US2676542A - Connector for reusable pressureresistant blasting cartridges - Google Patents

Description

April 1954 M. M. LILLY ETAL 2,676,542

CONNECTOR FOR REUSABLE PRESSURE-RESISTANT BLASTI'NG CARTRIDGES Filed Feb. 1a, 1953 F .5. g 4 y L [:1 I 5 f) 10 5 4 INVENTORS M.Lilly JameSRS /ed ATTORNEY Patented Apr. 27, 1954 acres-4a eo s eroago REUSABLE-PRESSIJEE- ,aasismm nrs rme" meanness MichaelsMxEilly; Charleston, .Va.,. andJames iP.,-Swed,..Gibbstnwn, N. J'.,. assignors==torE. 1.51m t p t .Nem ur e fil mnanriiwilminstnn. pel a corporation of Delaware iipplicatibn-Felirnary 18, 1 953, Serial-Nor3 -3-7 ,4 62

1.3 .Q e s {The present; invention relates :to.- an improued l;ass embly qfQl? proyiding. electrical connection -,f r orn:,,a source of electricalzzenergy ,tora blasting ,cartridge of. the reusable; pressure resistant tube It is an object of the present invention sto provide an improved assembly for making: el'ectricaL connectionwiththe firing head of; 21.2111188- sure-resistant blasting I tube. A further object is type; 5 to provide an assembly for making electrical The use ,of reusable pressure-resistant tube connection with: the fi'ring head of-ikapressure -re blastingcai tridgei in mining; operations; is rapidly sistant. blasting tube wherein the lead wires: will gainin wideacceptance. Essent-ially:, :the blastnot be. damaged by fragments:resulting from the fi .eartnidges consist ,of .a heavy steel tubular blasting action. Additional objects-:will 1986611 119 .bodyclosed at one ,end witha firing head and apparent as theinventioirisifurthendescribeda.

at the other endwith; a: pressurerresponsivedis- We have found that" the f-oregoing obj'ects -may .gakitguige; head;. The head: contains a cenbe attained when we providea socket on --the tra lly positioned electrodewhich extends intothe head end of a pressure-resistant blasting tubular bod-yandisinsulated from the, remainder cartridge; and a plug of suchsize aato formtight ,ottl re. blasting cartridge. Thadischarge head friction fit with the said socket firmly attached containqaa number of venting, apertures, usually to the lead wires. The-socket is-centrally posisloping outwardly toward the firing head end tionedat-the outside end of the firing heagd and of the cartridga.andivalyingimeans or a rupturathe insulated electrode within the firing head ble disc which will permit the sudden release of projects centrally into the space created by the gases under high pressure from within the tube. socket. The plug is of greater length than the The tube body contains the gas-producing charge, depth of the socket and is preferably molded which may be a substance capable of decomposabout the end of a pair of heavily insulated leading into gaseous material upon initiation, or may in wires. The end of the plug opposite the wire, be a liquefied or solidified form of a normally i. e., the end of the plug which is inserted into gaseous material. A typical charge of the former the socket, has a peripheral metal sleeve which type contains a large proportion of ammonium is connected to one of the lead-in wires, and a nitrate, and is initiated by means of an electrical transverse slot containing a metal liner connectheating element imbedded within the charge. A ed to the other lead-in wire. The liner is shorter typical example of the latter type substance is than the diameter of the plug so that it is not carbon dioxide solidified or liquefied under presin contact with the sleeve which is also slotted at sure and gasified by the heat produced by the the same points. When the plug is inserted into action of an exothermic starter mixture or by an the socket, the sleeve is in contact with the sides electrical resistance coil. The starter mixture is of the socket and the liner is in contact with the initiated by means of an electric squib or an electrode, thus providing the desired electrical electric heating element. contacts.

In use, the charged blasting tube is loaded into In order to more fully describe the present ina borehole after lead wires have been connected vention, reference is made to the accompanying to the firing head, and initiated by the applicadrawings, in which: tion of current through the lead wires. Due to Figure 1 represents a plan view of the blasting the shattering action of the suddenly released assembly i accordance t t present, inven gases, the entire assembly is frequently buried tion; under a mass Of broken fragments. Since the Figure 2 represents a partially sectional view of fragments have sharp edges and strike the asth assembly; sembly with considerable force, the lead wires Figure 3 represents a view of the plug from the are naturally subjected to severe abuse. Atonta t end; d tempts have been made to pr v de permanent Figure 4 represents a View of the plug from the connections where the lead wires were heavily side. shielded and firmly secured to the firing head. Referring to the figures in greater detail, I is a This assembly is both clostly to produce and tube body, generally of steel, of the pressure-redifiicult to repair. Another practice has been sistant cartridge, 2 is the discharge head which to use expendable wire at the portion near the contains the pressure-responsive release mechatube. The disadvantages of this practice are nism and the venting ports, 3 is the firing head, the time required for repeated connections, the 4 is the plug at the end of the insulated leadloss of wire, and the contamination of the matein wires, 5, 6, and I representing the individual rial being blasted. lead-in wire cores. 8 is a U-shaped metal liner inserted in slot I0 transversely across plug 4. 9 is a metal sleeve surrounding the slotted end of plug 4, being itself slotted in alignment with slot I 0. H is an electrode inside and insulated from firing head 3 by insulators I2, the latter being retained in position by element 13.

As is-shown in the drawings, lead-in wire core 6 is welded to sleeve 9 while lead-in wire core 1 is welded to line 8. When the plug is in the position shown in Figure 2, the sleeve 9 forms electrical contact with the firing head 3 and liner 8 forms electrical contact with the electrode II. In the preferred form of the invention, sleeve 9 will be forced inwardly on plug 4 by the insertion in the socket in firing head 3, and liner 8 will be expanded by the entrance of electrode l I, so that the plug 4 will be under compression, thus assuring retention of the plug 4 in the socket during the insertion of the assembly into a borehole, and also better electrical contact with the firing head 3 and the electrode H.

The assembly of the plug and blasting cartridge are secured together only by the friction fit. Thus, when the cartridge is initiated within a borehole an initial stream of gases issue through the space between the borehole and the cartridge outwardly at tremendous velocity. These gases have suflicient drag on the plug and lead-in wire to detach the plug from the firing head and blow it completely free from the fall of the material being blasted. The slot 10 permits shaking out any dirt and facilitates cleaning liner 8 to insure a good contacting surface, so that the plug assembly is ready for reuse by simply inserting into the firing-head socket of a charged blasting cartridge.

The plug is preferably molded directly onto the length of heavily insulated lead-in wires,

but clamp or screw connections may be used. Natural or synthetic rubber is the preferred resilient material of a non-conductive nature for fabrication of the plug, but materials such as synthetic polymers having the desired resilience may also be used. Accordingly, we intend to be limited only by the following claims:

We claim:

1. An improved blasting assembly of a reusable blasting cartridge of the type described herein and a detachable lead-in wire device adapted to be blown free and clear of the fall of blasted material by the discharge within a borehole of said cartridge which comprises a firing head at the initiation end of the cartridge containing a central cylindrical socket at the outside end thereof, an insulated electrode in axial alignment with said firing head and having one end projecting into said socket, and a cylindrical plug of a resilient non-conductive -material, a portion thereof being inserted in said socket, said portion having a metal sleeve about the periphery in contact with said firing head, a transverse slot across the end of said plug and sleeve containing a centrally positioned metal liner of shorter length than the diameter of the plug in contact with said electrode, said plug being secured to two insulated lead-in wires, one of which is connected to said metal sleeve and the other to said metal liner, said plug and sleeve forming a tight fit with said socket.

2. An assembly as claimed in claim 1, wherein the sleeve has a normal outside diameter slightly larger than the diameter of said socket.

3. An assembly as claimed in claim 1, wherein the plug is molded to the insulated lead-in wires.

No references cited.

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