US1614210A - Method of manufacturing watertight electric fuses - Google Patents

Description

N. SCHMITT Jan. 11', 1927.

"METHOD OF MANUFACTURING WATERTIGHT ELECTRIC FUSES Filed July 26. 1926 Fig.3

Patented Jan.'11,1 927.

UNITED STATE-S uh h nrcomps sonm'r'r, or mnnnnnossmr'z, qnnmfir. v t

amnion or mumc'runme Application and miss, 1926, Serial up.

In blasting operations .it frequently occurs that the 7 have to be carried out in wet rock or comp etely under water. Hence it is necessary that the electric fuses used shall 5 be made perfectly watertight, so that they shall not become uselessthrough the action of the water. The methods adopted hitherto with this object in view consist mainliyiig this, that the caps of the fuses are embe either directly'm the detonator or m a casing, into which the detonator is then cemented. As, however, all cementing materials more particularly the sulphur usually used for this purpose, contract when they solidify and the water would penetrate through the which the priming composition is attached.

In a construction of this kind the wiresare bound to become loose when handled, thus rendering the 'acking inell'ective. 7

It has also lieen p oposed to cement the fuse into a cast casing which is divided by a partition into two separate spaces, one of avhich receives the incandescent wire and priming composition and the other-the detonator. The carrying out of this idea is rendered difiicult'hy the complicated form of the casing, the manufacture of which is fairly expensive. But even in this construction water is not prevented from penetrating to the primary composition, which fails to act when wet.

' By pressing delay compositions into the fuse casing the fuse isrendered watertight on the side facing the detonator. On the 'other'side, however, is the cement for fixing the fuse wires into this casing as in fuses of the usual' kind which does not form a tight closure as already explained above. The present invention has for its object to re der both. the detonator and the primarfccmposition tight against the penetrawarnnrren'r rane'rmc seats:

125,019 and in Germany mm yiia, 1921s.

ti on of moisture without any casingin the simplest mannerfbythe following method. 7

In the accom anymgdrawmg:

Figures 1 an 2 are longitudinal sectional.

and side views respectively of the fuse. 1

Figure 3 is an elevation ofthe fuse fitted.

with a detonator. 4

- Figures 4, 5 and dareelevations of modifications of the invention.

The fuse head of electric mine fuses are embedded in 'some suitable material, as

shown in section in Fig. 1, and in elevation in Fig. 2, a being the fuse head, I; the leadin'g-in wires and a the embedding material. The embedding material may consist of resin, wax, paraflin, asphalt and the like or of mixtures of these materials or of other suitable materials, which, however, must have the requisite strength and toughness and be easily fused. 1 Y

When a fuse embedded in material of this kind is to be fitted with the detonator d (fig. 3), the latter is inserted in the hole in t e metal plate 6 which has been heated by steam or hot water, so as to rest on thesupport f. The fuse-head (Fig. '2) is then inserted in the detonator. The embedded material on the fuse head has a-conical shapev and the external dimensions are such that the lower end will fit tightly in the detonator. Through the detonator beingheated the surface of the embedded material will be melted, so that it canbe forced easi-- 1y down intothe detonator till the shoulder a. rests against the latter. This will bring about such an intimate and permanentIcoii-a; =nect1on between the fuse head and the detona tor that water cannot possibly penetrate.

The finished fuse is imnie'diatelypushed out of the hot plate by raising the plunger f and is ready 7 for transport and use. Fig. 4 shows the complete fuse which may be left mentally afi'ected. T For fuses which without detonators a modified form shall now he described. In Fig. 5 a fuse is shown embedded in the manner described, which has a tapered extension 7:. at its lower end. If a fuse head of this kind be immersed in melted embedding material up to the shoulder, a portion of the material will adfor weeks under water without being-detrL are to be transportedhere toit, giving it the shape shown. at k in Fi 6. By this method the fuse head descri ed is not only protected against damage, but also against being affected by water, to such an extent that the fuse head may lie in water for weeks without being detriin'entally afi'ected, even without the detonator, In addition to this the resent method reliders the use of paper and brass casin superfluous, as detonators may be placed on the fuse heads at the place where they are to be used, when they'wiil form a firm connection, owing to the conical shape of the head.

' What I claim is: y

1. A method of manufacturing watertight electric fuses, consisting in providing the fuse head'with aconical covering of an,

easily fusedmaterial, externally heating a detonator and inserting the said fuse head therein, whereby the two' are'oonnected together securel and in a watertight manner, as set forth. v

2. A method of manufacturing watertight electric fuses, consisting ,in providing the fuse head with a tapered extension, immersing the'said fuse head in'molten easily fused material, externally heating a detonator and inserting the said fuseheadtherein, whereby the two are connected together securely and in a watertight manner, as "set. forth.

In testimony whereof l havesigned my name to this specification.

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