US3895577A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Long burning delay blasting caps
Assignee: Ireco Inc
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Filing: 1973-09-25
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Granted: 1975-07-22
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Expires: 1993-09-25
Abstract
Abstract Delay type blasting caps in which the burning time of the delay fuse is at least 1.5 seconds per inch with accompanying low sensitivity to ignition, which, due to novel ignition system structure, provide for elimination of premature venting of heat and pressure required for ignition of the delay fuse and concomitant failure of the shot. The delay blasting caps include explosive base charge, primer, and delay charges in that order, and an ignition assembly above the delay charge, with or without an intermediately disposed wafer charge. The ignition assembly is a tube containing the ignition charge, as a core, having a heat of reaction of at least 50 calories per gram. When the wafer charge is included, the heat of reaction of the ignition charge is generally from 50 to about 100 calories per gram, and the heat of reaction of the wafer charge is from about 60 to 105 calories per gram; and when the ignition charge is the sole source of heat for ignition of the delay, its heat of reaction is higher, generally up to about 150 calories per gram, but higher in some embodiments, sometimes as high as about 600 calories per gram.
Inventors
- 👤 David T Zebree
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 15:21
CPC Classifications
F; F42; F42B; F42B3/00; F42B3/10; F42B3/16
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
203 words
A long burning delay blasting cap assembly which comprises, a closed shell, including a plug closure member therefor; an explosive base charge, a primer charge and a delay charge disposed in said shell in that order toward said plug closure, said base charge detonatable in response to detonation of said primer charge and said primer charge detonatable in response to burning of said delay charge, and said delay charge having a burning time of at least 1.5 seconds; an ignition assembly in said shell intermediate said plug closure and said delay charge, including a tube member and an ignition charge within said tube member as a core therein, and said core ignition charge having a heat of reaction of at least 50 calories per gram; a booster ignition charge having a heat of reaction of at least 60, but less than about 110, calories per gram intermediate said core ignition and delay charges, said booster ignition charge being ignitable in response to burning of said core ignition charge, and said delay charge being ignitable by heat and pressure from burning of said core and booster ignition charges; and means in said plug closure for support of initiator means for said core ignition charge.
Claim 2
Dependent Claim
203 words
A long burning delay blasting cap assembly which comprises, a closed shell, including a plug closure member therefor; an explosive base charge, a primer charge and a delay charge disposed in said shell in that order toward said plug closure, said base charge detonatable in response to detonation of said primer charge and said primer charge detonatable in response to burning of said delay charge, and said delay charge having a burning time of at least 1.5 seconds; an ignition assembly in said shell intermediate said plug closure and said delay charge, including a tube member and an ignition charge within said tube member as a core therein, and said core ignition charge having a heat of reaction of at least 50 calories per gram; a booster ignition charge having a heat of reaction of at least 60, but less than about 110, calories per gram intermediate said core ignition and delay charges, said booster ignition charge being ignitable in response to burning of said core ignition charge, and said delay charge being ignitable by heat and pressure from burning of said core and booster ignition charges; and means in said plug closure for support of initiator means for said core ignition charge.
Claim 3
Dependent Claim
45 words
A blasting cap assembly of claim 1 wherein said booster ignition charge has a heat of reaction of from about 60 to 105 calories per gram, and said core ignition charge has a heat of reaction of from about 70 to 100 calories per gram.
Claim 4
Dependent Claim
24 words
A blasting cap assembly of claim 2 wherein the burning time of said delay charge is from about 2 to 12 seconds per inch.
Claim 5
Dependent Claim
83 words
A blasting cap assembly of claim 3 wherein said shell is elongated and said plug closure is an end closure member therefor, said plug closure contains a passageway longitudinally extending therethrough in communication with the outside of said shell and with the interior thereof, for support of said initiator means, said tube member transversely closes said shell and extends longitudinally from said closure plug and is superposed on said booster ignition charge, and said booster ignition charge is superposed on said delay charge.
Claim 6
Dependent Claim
16 words
A blasting cap assembly of claim 4 wherein said delay charge is consolidated in said shell.
Claim 7
Dependent Claim
26 words
A blasting cap assembly of claim 4 wherein said delay charge forms a core of a metal tube transversely closing, and longitudinally extending in, said shell.
Claim 8
Dependent Claim
34 words
In a blasting cap assembly of claim 4, a detonator cord having a core loading of from 2 to 6 grains PETN (or equivalent) per foot supported in said passageway as said initiator means.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-07-21 | 1979-01-20 | 1979-07-22 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-07-21 | 1983-01-20 | 1983-07-22 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-07-21 | 1987-01-20 | 1987-07-22 | $7700.00 | Window Closed / Lapsed |