US1900624A - Safety device for blasting charges employed in mining and similar work - Google Patents

Description

March 7, 1933. Wy VORTMANN 1,900,624

SAFETY DEVICE FOR BLASTING CHARGES EMPLOYED IN MINING AND SIMILAR WORK Filed Jan. 16, 1951 7 7f4 A i Bf 7mm/MM Patented Mar. 7, 12933 STAT 'WALTER VOORTMAN'N, OF DORTMUND, GERMANY DEVICE FOB BLASTING CHARGES EMPLOYED IN MINING AND SIMILAR- WORK Application led January 16, 1931, Serial No. 509,247, and in Germany March 5, 1930.

This invention relates to a protective device for the blasting charges that are usual in mining and similar operations. It is y known to mount upon a blasting charge located in a bore hole, before tamping or stemming it, a plug that receives a pulling member, for the purpose of enabling the blasting cap to be pulled out again in the event of failure of the explosion, after the tamping that closes the bore hole, consisting of moist clay or the like,u has been removed.

The object of the present invention is to provide a protective device for the blasting charges that are usual in mining and similar 5 o erations, characterized by the feature that t e plug, made of an incombustible material, impregnated wood for example, or an incombustible articial material, is provided with two longitudinal bores, for the ignition wires and for the pulling member respectively, and

has on the outside axially arranged and prefv erably dovetail-shaped notches for the reception of supporting members for a partial charge. 4

According toy a further feature ofthe invention the bore in the plug for the pulling member is located centrally, and has at the inner end a conical expansion.

According to another feature of the invention the pulling member consists of an incombustible string or wire, which is held in the bore of the plu by a knot and preferably has a coloured mar 'ng.

invention the margins of the recesses in the plug for the supporting members are somewhat convergent towards one end, and the supporting members, which consist of incom- 40 bustible material, such as presspahn for example, are provided with transverse holes at their ends.

By locating the pulling member exactly in alinement with the axis of the bore hole for the blasting charge, and firmly connecting a partial charge with the plug by means of the supporting members, a reliable guidance y is established in the bore hole when inserting and withdrawing the plug. In consequence v of the coloured marking of the .string it can According to yet a further feature of thel at any time be ascertained how deep the plug is in the hole.

The invention is illustrated by way of example in the accompanying drawing, in

which Figure 1 shows a back view of the plug according to the invention.

\ Figure 2 a side view of the plug.

Figure 3 a side view of a plug with supporting members inserted and a partial charge fitted in, a

Figure 4 a side view of a supporting member, and

Figure 5 a blasting charge inserted in the e5 bore hole, on a smaller scale.

A cylindrical plug 1, illustrated in the drawing, preferably consists of an incombustible material, for instance impregnated wood or an articiflal material. The plug has in an axial direction a central cylindrical bore 2 for the reception of a pulling member, not shown, an incombustible string or wire a for example. The bore 2 is conically flared towards the inner end of the plug, and in this conical widening 3 is placed a knot on the pulling member, which prevents the string from being dragged out of the plug. Parallel to the bore 2 is provided a second bore 4, through which ignition wires c, c for the blasting cap d. In the cylindrical surface of the plug are cut dovetail-shaped grooves 5 and 6 parallel to the axis, which taper t0- wards the inside of the plug, as shown in Figure 2. Into the dovetail-shaped groves are inserted from the outside supporting memo bers 7 and 8, which likewise consist of an incombustible material, such as presspahn. The shape of these supporting members is externally adapted to the periphery of the e plug. The supporting members 7 and 8 are 90 long bars, which are provided inthe neighbourhood of their ends with transverse holes 9 and 10 respectively. Owing to the fact that the grooves 5 and 6 taper inwards to some extent, the supporting members are firmly connected with the plug. j

The supporting mem ers 7 and 8 serve to hold a partial charge e inserted between them`I The ignition wires are passed y through the bores 4, and the inner end of the partial charge is held by a string f of incombustible material, which passes through the holes 9 and l0.

If no partial charge is desired between the bars they may be omitted, and the ignition wires may be passed through the laterally provided grooves. The plug may also Ibe directly connected with the fuse, and the ignition Wires are then so strong that they serve as a pulling member.

When inserting the partial charge connected with the plug, the whole is introduced so far into the bore hole that the inner ends of the supporting members come into contact with the preceding partial charge, as shown in Figure. The string, not shown, projecting from the outer end of the plug, and preferably having a colored marking, every Centimetres for instance, indicates how deep the plug is in the bore hole.

The free end of the bore hole is closedin the usual manner, after the insertion of the i plug, by the so-called tamping or stemming g or moist clay or the like. The string or the pulling member then projects out, as do also the ignition wires.

If a miss-fire occurs, the tamping is blown out of the bore hole .by compressed air by means of a blast pipe having an internal `diameter of about l() millmetres, and by exerting a pull on the string or wire a or on the ignition wires, the plug can be drawn out, together with the partial charge (if any) connected with it. In Figure 5 three partial charges are shown, inserted in one bore hole.

What I claim is 1. A safety device for blasting charges employed in mining and similar operations, consisting in the combination of a cylindrical plug of incombustible material provided with a central passage, and a pulling member anchored axially of the passage in the plug, the pulling member being marked at definite distances.

2. A safety device for blasting charges employed in mining and similar operations, consisting in the combination of a cylindrical plug of incombustible material provided with a central passage, and a pulling member anchored axially of the passage in the plug,y

ignition wires, the plug being formed with a second passage, parallel to the said central passage, for the ignition Wires.

3. A safety device for blasting charges employed in mining and similar operations, consisting in the combination of a cylindrical plug of incombustible material and a pulling member attached centrally to the plug, ignition wires, the plug being formed with a central passage for the pulling member, and with a second passage, parallel to the said central passage, for the ignition wires, and with dovetail-shaped slots in its cylindrical surface, supporting members engaging in the vLacasse-st said slots, and a partial charge held between the supporting members.

4. A safety device for blasting charges employed in mining and similar operations, consistin in the combination of a cylindrical plug of mcombustible material, supporting members connected with the plug, a string holding the supporting members together, a partial charge held by the supporting members, and a pulling member attached centrally to the plug.

5. A safety device for blasting charges employed in mining and similar operations, consisting in the combination of a cylindrical plug of incombustible material, supporting members connected with the plug, a. string holding the supporting members .together, a partial charge held by the supporting members, and a pulling member attached centrally to the plug, the pulling member being marked at definite distances.

6. A safety device for blasting charges employed in mining and similar operations, consisting in the combination of a cylindrical plug of incombustible material, and a pulling member attached centrally to the plug, the plug being formed with a central passage for the pulling member, supporting members connected with the plug, a string holding the supporting members together, a partial charge he d by the supporting members, a blasting cap, and ignition wires for the electrical ignition of the blasting cap.

In testimony whereof I have signed my name to this specification.

WALTER VOORTMANN.

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