초록 ▼

A delay blasting cap having improved uniformity and predictability of delay time, and less susceptible to timing change as a result of a change in the medium or temperature surrounding the cap, has a polyolefin or polyfluorocarbon carrier capsule or tube for the delay charge, and preferably a rigid

A delay blasting cap having improved uniformity and predictability of delay time, and less susceptible to timing change as a result of a change in the medium or temperature surrounding the cap, has a polyolefin or polyfluorocarbon carrier capsule or tube for the delay charge, and preferably a rigid metal capsule holding the delay charge in place. Preferably, the delay carrier is a polyethylene capsule, which inhibits the priming charge from penetrating into the delay charge during the assembling of the cap.

대표청구항 ▼

In a delay blasting cap comprising a tubular metal shell integrally closed at one end and containing, in sequence from the closed end, (a) a base charge of a detonating explosive composition, (b) a priming charge of a heat-sensitive detonating explosive composition, (c) a delay charge of an exotherm

In a delay blasting cap comprising a tubular metal shell integrally closed at one end and containing, in sequence from the closed end, (a) a base charge of a detonating explosive composition, (b) a priming charge of a heat-sensitive detonating explosive composition, (c) a delay charge of an exothermic-burning composition, and (d) an ignition assembly for igniting said delay charge, the improvement comprising a carrier element for said delay charge, said carrier element consisting of a capsule or tube whose side wall provides a layer of polyethylene, polypropylene, or polytetrafluoroethylene between said delay charge and the inner wall of said tubular metal shell, said layer having a thickness in the range of about from 0.5 mm to 1.7 mm, said delay charge having been pressed into said carrier element with a force of at least about 890 Newtons, and said priming charge being inhibited from penetrating into said delay charge by at least one of the following means: (1) pressing said priming charge into said shell with a force of at least about 225 Newtons, and (2) a barrier layer between said delay charge and said priming charge. In a delay blasting cap comprising a tubular metal shell integrally closed at one end and containing, in sequence from the closed end, (a) a base charge of a detonating explosive composition, (b) a priming charge of a heat-sensitive detonating explosive composition, (c) a delay charge of an exothermic-burning composition, and (d) an ignition assembly for igniting said delay charge, the improvement comprising (1) a tubular polyolefin or polyfluorocarbon capsule holding said delay charge and nested within said tubular metal shell, said tubular polyolefin or polyfluorocarbon capsule having one open extremity and a closure at the other extremity provided with an axial orifice therethrough, said closure on said polyolefin or polyfluorocarbon capsule being adjacent to said priming charge; and (2) a tubular rigid metal capsule nested within said polyolefin or polyfluorocarbon delay-charge-carrying capsule, said rigid metal capsule having one open extremity and a closure at the other extremity provided with an axial orifice therethrough, said closure on said rigid metal capsule being adjacent to said delay charge.