US2327902A - Safety blasting cap - Google Patents

Description

ug. 24, 1943- .1. G. .JOHNSON 2,327,902

SAFETY BLASTING CAP Filed NOV. 14, 1940 HU @mao/a Horn@ HUH I ,UUR

UNITED STATES PATENT OFFICE SAFETY BLASTING CAP John G. Johnson, Lead City, S. Dak.

Application November 14, 1940, Serial No. 365,701

2 Claims.

The present invention relates to new and useful improvements in blasting caps for use in all kinds of blasting operations, including coal mining, wherein dynamite or highly explosive powder is used, and has for its primary object to provide, in a manner as hereinafter set forth, a device of this character which, in the event of a misiire, will become harmless after a predetermined length of time, thereby promoting safety.

Another very important object oi the invention is to provide a blasting cap of the aforementioned character which is adapted to be bent at spaced points at relatively sharp or acute angles without breaking.

Other objects of the invention are to provide a blasting cap of the character described which will be comparatively simple in construction. highly eiilcient and reliable in use, light in weight and which may be manufactured at low cost.

All of the foregoing and still further objects and advantages oi the invention will become apparent from a study oi' the following specilication, taken in connection with the accompany,- ing drawing wherein like characters of reference designate corresponding parts throughout the several views, and wherein:

Figure 1 is a view in side elevation oi a safety blasting cap constructed in accordance with the present invention, showing said cap in position in a charge which has been placed upside down in a hole.

Figure 2 is a view in vertical longitudinal section through the cap.

Figure 3 is a perspective view of the cap.

Referring now to the drawing in detail, it

will be seen that the embodiment of the invention which has been illustrated comprises a tubular casing I which is formed oi' rolled paper. The paper of which the rolled tubular casing I is made is oi a texture to absorb and permit the passage of moisture or water in a predetermined length of time. One end of the tubular casing I is closed, as at 2.

The closed end portion of the tubular casing I is internally reduced for providing an explosive chamber 3. The explosive chamber 3 is formed from suitable light cardboard or paper rolled into a tube 4. Thus, a shoulder or abutment 5 is provided in this end portion oi the tubular casing I.

The tubular casing I is of Just suilicient diameter to nicely receive the usual fuse 8. However, the fuse 8 is too large to enter the explosive 4 chamber 3 but engages or abuts the shoulder i. Split clamps 1 are bent around the tubular casing I at longitudinally spaced points for contracting said casing and frictionally securingv same on the fuse 6. The clamps 1 also positively prevent the tubular casing I from unrolling.

In Figure 1 of the drawing, the reference numeral 8 designates a charge in a, hole 9. When using the cap constituting the present inven.

tion, the fuse 6 is inserted in the tubular casing and the charge is readyI to be red. Should a misiire occur, moisture or water will, within a predetermined time, penetrate the tubular cas- 'ing I and the explosive chamber 4 and render the powder or dynamite in said chamber 4 harmless. It isv believed that the many advantages of a blasting cap constructed in accordance with the present invention will be readily understood and although a preferred embodiment of the device is as illustrated and described, it is to be understood that changes in the details of construction may be resorted to which will fall within the scope of the invention as claimed.

What is claimed is: 1. A blasting cap comprising-a rolled tube of absorbent paper capable of constituting a exible casing of uniform diameter for the reception of a fuse in one end. said casing including an internally reduced, closed end portion consti- 'tuting a chamber at the other end of the tube,

an explosive in said chamber, and clamps detachably securedto the -casing for contracting the casing and frictionally securing same on a fuse.

2. A blasting cap oi the character described comprising a tubular casing of uniform diameter, said casing being constructed of bendable, absorbent material ior the reception of a fuse in one end of the casing. a tubular explosive chamber in the other end portion oi.' the casing. an-

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