US2123996A

US2123996A - Electric blasting cap

Info

Publication number: US2123996A
Application number: US73602A
Authority: US
Inventors: William C Hunt
Original assignee: Hercules Powder Co
Current assignee: Hercules Powder Co
Priority date: 1936-04-10
Filing date: 1936-04-10
Publication date: 1938-07-19
Anticipated expiration: 1955-07-19

Description

July 19, 1938. w. c, HUNT 2,123,996

July 19, 1938.

W. C. HUNT ELECTRIC BLASTING CAP Filed April 10, 1936 2 Sheets-Sheet 2 FIG.5

FIG.4

FIG.7

FIG.6

S M N M 2 R E W V T A Y B M M Patented July 19, 1938 UNITED STATES PATENT OFFICE Application April 10, 1936, Serial No. 73,602

4 Claims.

.This invention relates to a new and improved electric blasting cap, such as is used in firing commercial explosives, and more particularly relates to an arrangement whereby blasting caps may be protected during shipment and storage,

with avoidance of accidental discharge.

As is well known, electric blasting caps are equipped with a pair of lead wires, by which they are connected to a firing circuit after they have been placed within an explosive charge to be detonated. Usually, forthe purpose of shipment and storage of such electric blasting caps, the lead wires, often of considerable length, are bundled and tied centrally of thewire bundle, with the free ends of the lead wires and the v cap at opposite ends of the bundle.

The customary bundling and tying of the lead wires .of such caps is ordinarily sufficient to enable packaging and handling of the caps, but, since the cap itself is wholly unprotected, it is liable to accidental firing by any shock to which it may be subjected, for example, by striking another cap in the package, or by striking the wall of a package during shipment, from being 25 dropped during handling, or otherwise. Such caps are usually loaded with mercury fulminate,

diazodinltrophenol, or similar, sensitive high explosive, so that the possibility of accidental firing presents a certain amount of hazard.

Heretofore, attempts have been made to avoid this disadvantage of having the cap exposed to shock, e. g. as in United States Let ers Patents 1,912,432 and 1,631,756, but such attempts have not wholly accomplished their purpose, or have 35 involved serious difficulties in removing the lead wires from the bundle without tangllng the wires. Moreover, such attempts in the past have necessitated the use of separate elements to form the core and the protective sleeve and' the insertion 40 of the wire bundle within said sleeve element, all at considerable cost of materials and labor in packing such electric blasting caps.

It is theobject of this invention to provide an arrangement consisting of the lead wires only, whereby such caps will be adequately protected from shock, whether during shipment, storage, or handling, and at the same time provide a ready method of dis-assembling the package without 50 tangling the lead wires.

In accordance with this invention there is provided a protector for the blasting cap in the form' of a self-supporting coil, without the use of a sleeve or tube to form either core of the coil or tsprotecticn over the coil, such as has been necessary in the past withhelically wound lead wires.

Having now indicated in a general Way the nature and purpose of my invention, I shall proceed to a detailed description of preferred embodiments thereof, with reference to the accompanying drawings, in which Figure 1 is a side view of an electric blasting cap package embodying my invention, Figure 2 is a view in elevation of the device of Figure 1, Figure 3 is a modification. of the device of Figure 1, Figure 4 an end view of the device embodying my invention where it is desired to use the invention on short lengths of lead wires, and Figure 5 a side view of the device of Figure 4, Figure 6 an end view of a modification of the device of Figures 4 and 5, and Figure '7 a side view of the device shown in Figure 5.

Referring more particularly to Figure l of the accompanying drawings, l indicates an electric blasting cap, provided with lead wires 2 which are wound, beginning with the lead wires adjacent to the cap, in the form of what is commonly known as a honeycomb coil," by moving the lead wires, uring the coiling operation on a mandrel whose diameter is approximately the length of the blasting cap, from one end of the coil to the other, so that said lead wires cross the wires beneath them at an angle to the underlying wires, and also form a lock for the underlying wires at the ends of the coil, to prevent collapse of the coil, allas is shown in greater detail in Figures 2, 5, and 7. When the coil has been wound as described, a loop, 2 is formed from the the extending ends of the lead wires, and the end of lead wires 2 passed through said loop, the loop placed about the exterior of the honeycomb coil, pulled tight, and the ends of the lead wires 2 bent back to lock the loop in place. The coil is then removed from the mandrel, and will be found to be interlocked from layer to layer and will be self-supporting, being prevented from uncoiling by the exterior loop '2 The blasting cap I is then inserted into the open space forming the core of the coil and is retained there by resting with the base of the blasting cap pressed against the interior of the coil by the spring effect of lead wires 2. The uninsulated ends of thelead wires 2 may be suitably short-circuited, by twisting them together or by twisting them, as shown by 2', about a bare piece of heavier wire 3.

.It will be noted that to uncoil the lead wires for use in blasting operations, it will be necessary only to pull the blasting cap I from the core of the coil, whereupon lead wires 2 uncoil from the interior of the honeycomb coil as the lead wires arepulled forth, and do so without interference from any pasteboard coil core heretofore used, and without curling or kinking, as has been experienced with blasting cap coils heretofore employed.

Referring now specifically to Figure 3 of the accompanying drawings, which represents a modification of my invention shown in Figure 1, it will be noted that thehoneycomb coil of the lead wires is formed by winding on a mandrel whose diameter is approximately the length of the blasting cap, the lead wires 2 starting from the uninsulated extremities of said lead wires 2', forming a loop 2 of the lead wires 2 after the coil is wound, putting the blasting cap l and lead wires "through said loop and bending back cap and lead wires to form a lock, then placing the blasting cap within the core of the honeycomb coil with the bottom of the blasting cap resting against the interior of the core of the coil and retained in position by the spring of lead wires 2.

It will be noted that, in the form of my invention shown in Figure 3, the bare ends (2') of the lead wires are protected from contact with sources of electricity by being within the core of the honeycomb coil,-- and consequently do not ordinarily require short-circuiting for protection from stray currents, while at the same time the blasting cap is also protected from striking objects by being within the hollow core of the coil. It will also be noted that this form of my invention also enables the lead wires to be uncoiled from the center of the honeycomb coil by merely pulling out the end 2 of the lead wires, and this without the undesirable curling and kinking heretofore experienced with other forms of cap packages.

Referring now specifically to Figures 4 and 5 of the accompanying drawings, which illustrate a preferred embodiment of my invention with the use of comparatively short lengths of lead wire, i represents the blasting cap, 2 the lead wires of said blasting cap, 2 the uninsulated ends of said lead wires, and 4 a band or strap, e. g., of tape or rubber band, to tie down the last convolution of the honeycomb coil. In this embodiment of my invention, the lead wires 2 are coiled in the criss-cross, honeycomb manner hereinbefore described, upon a mandrel whose diameter is slight- 1y greater than the diameter of the blasting cap, commencing with the portions of the lead wires nearest the cap, and, when the coil has been formed, the coil is removed from the mandrel, the blasting cap inserted in the core of the coil, where it is retained by the spring effect of lead wires 2, and by the retaining band or strap d placed about the exterior of the coil.

Referring now specifically to Figures 6 and 7 of the accompanying drawings, which represent a modification of my invention shown in Figures 4 and 5, it will be noted that the winding of the honeycomb coil is commenced with the uninsulated' ends of the lead wires, and, after the winding of the coil is completed, the cap and its lead wires are then inserted into the hollow case of the coil and retained there by the spring effect of the lead wires. The band or strap 5 is used on the exterior of the coil, as hereinbefore described.

It will be noted that in the form of my invention shown in Figures 4 to 7 inclusive, the uncoiling of the lead wires before use in blasting operations will be from the interior of the honeycomb coil, without the usual disadvantages of curling and kinking heretofore experienced.

In the winding of the lead wires to form the honeycomb coil of my invention I prefer to use coil winders ordinarily used to form such coils, although I may use any suitable apparatus therefor.

It will be noted particularly, that I do not require any supports or end pieces for my honeycomb coil, nor, as has been stated, any tube with .in the coil. Thus, except for the binding strip of Figures 5 and 7, I form my blasting cap package solely of the lead wires per se, without resort to the use of any additional materials.

It will be noted that my blasting cap assembly lends itself with advantage to the packing of several such coils in one box, without the complication of entangling lead wires of one blasting cap with another, and without the large packing box or case heretofore required.

What I claim and desire to protect by Letters Patent is:

1. A prepared package comprising a blasting cap having a pair of lead wires wound in the form of a substantially rigid self-supporting, honeycomb coil, the blasting cap being within said honeycomb coil.

2. A prepared package comprising a blasting cap having a pair of lead wires wound in the form. of a substantially rigid self-supporting, honeycomb coil, the blasting cap being within said honeycomb coil, and a 'wire tie composed of the end portion of the lead wires about the exterior of said coil and adapted to prevent uncoiling of said coil.

3. A prepared package comprising a blasting cap having a pair of lead wires wound in the form of a substantially rigid self-supporting, honeycomb coil, said coil having a core diameter approximately the length of said blasting cap, and a blasting cap in said core of said honeycomb coil.

4. A prepared package comprising a blastng cap having a pair of lead wires wound in the form of a substantially rigid self-supporting, honeycomb coil, said coil having a core diameter approximately the diameter of said blasting cap, and a blasting cap in said core of said honeycomb coil.

WILLIAM C. HUNT.