US2837996A

US2837996A - Explosive charge

Info

Publication number: US2837996A
Application number: US427464A
Authority: US
Inventors: Robert L Klotz
Original assignee: Seismograph Service Corp
Current assignee: Seismograph Service Corp
Priority date: 1954-05-04
Filing date: 1954-05-04
Publication date: 1958-06-10
Anticipated expiration: 1975-06-10

Description

June 10, 1958 R. l.. KLoTz l 2,837,996

ExPLos1vE- CHARGE Filed May 4. 1954 IN VEN TOR.

EXPLSIVE CHARGE Application May d, 1954, Serial No. 427,464

3 Claims. (Cl. 1432-24) The present invention relates to improvements in explosive charges and more particularly to improved explosive charge containers equipped with facilities for insuring complete detonation of a number of explosive cartridges when arranged in end-to-end relationship to form an elongated explosive column.

One method of insuring complete detonation of a long column of low sensitivity explosives of the type `commonly used in mining, quarrying and similar operations, is described and claimed in co-pending application rSerial No. 746,578, tiled May 7, 1947, by Robert l.. Klotz, Jr., and assigned to the same assignee as the ,present invention, which matured into Patent .'No. 2,683,414 on July 13, 1954. The above identiiied application discloses an arrangement wherein a plurality of cartridges, at least some of which have jet yforming cavities in one end, are aligned in end-to-end relationship to form an explosive column of the desired length. When the column is detonated, the jet forming cavity inthe end of each cartridge of the column which iS so equipped produces an explosive jetv which is directed into the next adjacent cartridge, thereby to strengthen and revitalize the cletonatingY wave travelingkalong the column. The present invention relates to improved explosive charge containers for instrumenting the arrangement disclosed inthe ide'ntied Klotz application in a simple and economical manner and for facilitating `align.- ment of the -cartridge containers in the desired end-to end relationship in a shot hole.

It is an object of the present invention to .provide Van improved container assembly 'for explosive Charges..

Itis another object of the invention to .provide explosive cartridges which are self-centering -whenv stacked end-to-end to form a column.

It is a further object of the ypresent invention `to provide an improved container foriexplosive charges which is so .formed and arranged that when two cartridges are stacked end-to-end they are self-centered and a vjet forming cavity is provided in one end wall of one of v.the cartridge containers for producing an explosive jet'upon tes Patent() ICC Itis a still further object of the present invention to provide an improved elongated explosive charge made up `of a plurality of self-centering cartridges and pro- A vided with jet forming cavities at spaced points along the charge which function to insure complete detonation of all of the explosive material in the charge. y

Further objects and advantages of the present invention will become apparent as the following description proceeds, and the features of novelty which characterize the invention will be pointed out with particularity in the claims annexed to and forming a part of this specification.

For -a better understanding of the present invention, reference may be had to the accompanying drawing, in

which:

Fig. l is a view of a charge formed of a plurality of ,to Fig. l thereof, there is illustrated an explosive charge p yor column, generally designated by the reference numeral 10, and comprising a plurality of explosive cartridges 1 2 arranged in end-to-end relationship Within a shot hole `11 ,drilled into the earth. In mining and quarryingy operations, in particular, it iS conventional practice to simply lower or push the cartridges 12 endwise into vthe shot 4hole 11 to form the column 10. The present 'proved cartridge is particularly well adapted for this type of handling, as will be apparent from the follow,.- ing description thereof.

lt Ais well known that Athe de tonation or propagation wave traversing a column of `explosive material tends to become less intense the further the detonating wave travels from 'the point of initiation. -"lhis'tendency increases as f the diameter of the explosive column decreases. It 3150 detonation of the onecartridge which is directed into the adjacent end of the other cartridge. y

According to a further object of vthe invention, one end wall of the present improved explosives container is provided with end wall parts defining an inwardly extending stand-olf chamber which is radapted to be ax ially aligned with the jet forming cavity in the opposite end wall of an identical container when the two containers are arranged in end-to-end relationship.

ln accordance with still another object ,of the inverttion, the present improved container is provided with exceedingly simple facilities for self-centering two or more stacked cartridges as they are placed one ,on top of the other, so that the jet forming cavity provided in one end of one cartridge container 'is automatically brought into registry with the standfof cavityor chamber provided in the opposite end of the ahuttingfcartridge container.

vincreases as the pressure, Ysuch as the lluid tamping pressure used in the shot 'holel increases, and asthe sensitivity of the explosive material used is decreased. As a CQI1= sequence, only a portion lof the explosive material pro,- vided in along column of low sensitivi-ty explosive mterial maybe exploded in response to detonation of the `column `atone end thereof. Moreover, when the column Yis sectionalized, as by stacking a number of cartridges :in the manner described above, any foreign matter suchfas dirt, water, etc. which may inadvertently get ybetween ythe ends of any pair of abutting cartridges, in many cases has the effect of attenuating the detonating wave as it travels from onecartridge to theabutting cartridge tofthe point Where Vthe abutting cartridge is not detonated. Any such undetonatedexplosivematerial used in Ia given 4charge is not only a Waste of material, but, in 'gadditiom constitutes an explosives lhazard which remains 'after the blast.- f'

conical iet forming Cavity 14a in theexplbsive material disposed Vat the bottom of each ica fridge, a genial jet termina cavity .2Gb in the .esplosi-xe;materialeslispesed at the bottom of each cartridge, and a` cylindrical stand-olf 2,831,996 Patented June 10, 1958V strength.

chamber 14h in the explosive material disposed at the top of each cartridge More specifically, each container 14 comprises an elongated cylindrical body portion 15 having a cone-shaped bottom wall 16 integrally formed therewith and a top closure member 17. Many explosive cartridges presently sold commercially include a container 14 made of heavy carboard or other material havingrelatively little If the container 14 is comprised of such material, it may be diliicult to maintain the desired conical shape of the bottom wall 16. Accordingly, if the rcontainer 14 is made of such material a metallic backing or liner plate 19 may be provided within the container 14. This plate is conically shaped to conform to the configuration of the bottom wall 16 and functions to reinforce the same.

The top closure member 17 has an end closure wall portion 17a 4of truste-conical or convex coniguration which matches the concave configuration ofthe end closure wall 16, so that -the two end closure walls will seat in mating engagement when two or more cartridges are stacked in the manner illustrated in Figs. l and 2V of the drawing. In addition, the closure member is provided with a flange 17b which tightly embraces andV may be adhesively secured to the rim ofthe container body porr- Ation A15 after the container body portion is filled with explosive material 13.

For the purpose of defining the stand-oli chamber 14b in the explosive material 13 provided at the upper end of each cartridge, the end closure member 17 sealing the upper end of the cartridge is provided with a formed downwardly extending portion 20 loc-ated at the center of the closure member. This formed portion of the closure member is illustrated as being of generally cylindrical configuration and, as shown, is adapted to be aligned with the center of the end wall 16 in `the adjacent abutting cartridge when two or more cartridges are stacked or otherwise arranged in end-to-end relationship. At its bottom end, the formed portion 20 is provided with a coneshaped end wall 20a which denes the jet forming cavity 2Gb in the explosive material 13 disposed at the top of the container. As Will be understood, the height of the stand-off chamber or well 1417 defined by the formed wall portion 2t) of the closure member 17 for each cartridge delines the stand-off distance between the twojet forming cavities 14a and 20b.

As will be evident from the above explanation with reference to Fig. 2 of the drawing, by making the end closure wall portion 17a of the end closure member 17 of frusto-conical configuration, the desired jet forming cavity 14a is formed between two stacked cartridges incident to the placing of the cartridges in end-to-end relationship. A second jet forming cavity 20b for producing an explosive jet effect in a direction opposite to the explosive jet produced by the cavity 14a is also provided between the two stacked cartridges incident to the placing of the cartridges in end-to-end relationship. These two jet forming cavities are separated by the stand-olf chamber 1417.

closure walls

16 and 17a insure automatic alignment or centering of the cartridges as the cartridges are dropped into the shot hole 11 one on top yof the other, or are successively lowered or pushed into a horizontally or vertically extending shot hole. Thus, if the uppermost cartridge of the column shown in Figs. l and 2 is lowered into the shot hole 11, this cartridge is automatically moved into vertical alignment with the other cartridges of the column through the camming action which occurs The concial configurations of the end when the cone-shaped end closure wall 16 contacts the l conical surfaces of the end closure member 17 forming a part of the next lower cartridge container. Since the engaged conical surfaces of the contacting

end closure walls

16 and 17a are of mating configurations, the jet forming cavity 14a is conned to that area of the end closure wall 16 which is directly opposite or in registra- 'tion with the stand-off cavity or chamber 14b in the contacting end closure member 1'7. Moreover, the mating engagement of the contacting end closure walls serves to seal the cavities 14a and 1411 formed between the walls against the entry of dirt and tamping fluid into these cavities during the charge tamping 'operation which is, of course, performed after the shot hole 11 is loaded with the charge 10.

As will be apparent from the above explanation, the purpose of providing the described container end wall `configurations to define the cavities 14a and Ztb when the cartridges are assembled into a column is to permit the well known Munroe Effect, i. e., directionalized explosive etect, to be obtained. In other words, each cavity 14a or 2Gb acts to redistribute and concentrate the energy of the portion of the explosive material nearest the cavity. Each stand-'oit chamber 14h permits the explosive jet to form. More specifically, if the explosive column 10 is detonated from the top as seen in Fig. l, the explosive forces developed at the surface of each cartridge container end wall 16 in registry with the cavity 14b of the next lower cartridge, meet at the axis `of the cavity 14a within the cavity 14h of the next lower cartridge and add vectorially, thereby to effect concentration of explosive energy into a jet which is directed into the explosive material of the next lower cartridge. Alternatively, if the explosive column 10 is detonated from its bottom end, an upwardly directed explo- 'sive jet is produced by the jet forming cavity 20h in each cartridge, which is directed into the explosive material of the next higher cartridge. As a further alternative, if the explosive column 10 is detonated -intermediate its ends, those jet forming cavities 14a which Vare disposed below the point of initial detonation are effective to produce downwardly -directed explosive jets Vand those jet forming cavities 2011 which are disposed `above the point of initial detonation are effective to produce upwardly directed explosive jets.

In order to insure that the shapes of the end closure walls of each cartridge will be preserved, it is desirable to employ relatively rigid material, such as heavy cardboard or theY like, in the'construction of the end closure member 17 and the container body portion 15. In addition, the backing o'r linerplate 19 may be used, if desired, to insure preservation of the conguration of each end closure wall 16. As illustrated in Fig. 4 of the drawing, frangible sealing'V disks 21 and 22 may be adhesively securedto the

end closure walls

16 and 17a of each container 14 Yto cover and seal the cavities 14a and 14b thereof against uid entry into these cavities.

I n use, the cartridges 12 are arrangedin end-to-end relationship with the apexes of the cone-shaped cavities 14apointing toward the point of detonation of the column thus formed. Thus when the cartridges are arranged in the manner shown in Fig. 1 with a detonating cap or fuse123 located at the top of the column and connected to the fuse-wires indicated at 24, the apexes of the cavities 14a in the cartridges 12 point upwardly toward the cap 23 and the apexes of- Vthe cavities 20b point downwardly. The "cylindrically shaped cavity or chamber 14b in the top cartridge 12 of the column may be used to house the detonating cap 23. In such case, the cavities 14b are electivt-:ftoproduceV the desired downwardly directed explosive jets from cartridge to cartridge in the manner explained above. However, under certain conditions it may be desirable to detonate the charge from the bottom, in which c ase the'cavities 20b are effective to produce the desired upvvardlyv directed explosive jets from cartridge to4 cartridge in the manner explained above. It will be understood that theecolumn may also be detonated from an intermediate point. In such case and as explained above, toward the cap 23 regardless of its location in the column. Thus if the cap -is disposed in the middle of the explosive column, then the cavities 20b above the detonatingV capare effective and the cavities 14a below the cap are effective.

In the modifiedv embodiment of the invention illustrated in-'Fig 3, the concave, convex end wall' configurations are also utilized to obtainthe above-,described centering action asthe Cartridges 12 are arranged in end-to-end relationship. In this embodiment, however, the bottom end wall 116 is of convex ,configurationY and the top closure member 117i is o'f concaveconguration. The end closure member 117 of each container is provided with a downwardly extending rim for embracing `the top of the cylindrical container walls 115. For the purpose of providing two oppositely directed jet forming cavities l14a and 116a having a stand-oft chamber 114b therebetween in the explosive material contained within two abutting cartridges 12, a small hollow element 11e is provided in each container. This element, which may be formed of the same material as the container 14 or of any appropriate metal or plastic, has a cylindrical wall 114e defining the cylindrical stand-olf chamber 1ll4b and a cone-shaped top end wall 114d defining the jet forming cavity 1l4a in the explosive material contained within the container 14 in which the element 114 is provided. The element 114 is centrally disposed within the container 14 and the lower edge of the cylindrical wall 114C is adhesively or otherwise secured to the inner surface of the bottom end wall 116, so that the jet forming cavity 116g is formed by the central portion of the conc-shaped bottom end wall 116.

With the modified container arrangement illustrated in Fig. 3 of the drawing, the desired self-centering of the cartridges 12 as they are stacked is obtained through the coaction between the conical

end closure walls

116 and 117 in a manner which will be clearly apparent from the above explanation with reference to the embodiment of the invention illustrated in Fig. 2 of the drawing. Also, the

jet forming cavities

114a and 116a, and the stand-off chamber 114b function in the exact manner explained above with reference to the corresponding cavities 14a, 20b and 14b of the Fig. 2 embodiment of the invention. It will be understood, however, that in using the Fig. 3 embodiment of the invention, the jet forming cavity lla is formed in the explosive material located at the top of each cartridge 12 as the bottom end wall 116 of another cartridge is seated on the top closure member 117 of the cartridge. v

By employing the improved cartridge and container arrangements described above, a high intensity detonation jet is formed and directed from each cartridge into the next succeeding cartridge in the column which insures complete detonation of all explosive material in the column. Also by employing the present improved cartridges and containers, it is possible to use less sensitive explosives which are less expensive. Furthermore much longer columns may be detonated and propagation of the explosive effect is assured even where there is a substantial space between the cartridges, which space may be filled with air, water, mud, or the like.

It will be apparent to those skilled in the art that the present invention is not limited to the particular construction shown but that changes and modifications may be made without departing from the spirit and scope of the present invention. It is aimed in the appended claims to cover all such changes and modifications.

What is claimed as new and desired to be secured by Letters Patent of the United States is:

1. An explosive cartridge adapted for alignment wit-h other identical cartridges to form an elongated column of explosives, comprising a container for explosive material, one end of said container being provided with a concave shaped end wall and the other end of said container being provided with a convex shaped end wall, the convex shaped end wall of said container being shaped and dimensioned to coact with the conc-ave shaped end wall of an adjacent identical container to bring the two containers into axial alignment as the cartridges are asa` liner extending inwardly of'said first-named container from its convex shaped end wall and coacting-'withthe concave shaped end wall of s aid adjacent container to define first and second spaced apart and oppositely directed jet `forming cavitiesfin the explosive material contained within the two containers, said liner defining a hollow standoff chamber extending axially of said first named'container and having opposed ends one ofV which opens to the concave shaped end Wall of said adjacent container so that the 'latter end wall cooperates with the lliner to define said first jet forming cavity, said liner also being shaped to define said second jet forming cavity at the `other end lof and directed into lsaid standoff charn'ber and extending into the explosive material in said firs-tnamed container.

Y 2. An explosive cartridge adapted for alignment with 'other identi-cal cartridges to form an elongated column of explosives, comprising a container for explosive material, one end yof said container being provided with a concave, conically shaped end wall and the other end of said container fbeing provided with a convex c-onically Ishaped end wall having the same cone angle as said concave shape-d end wall, 'the convex `shaped end wall of said container being shaped and dimensioned to coact with Ithe concave shape-d end wall of an adjacent identical container tto Abring the two containers into axial alignment as Ithe cartridges `are assembled into a column, and structural means comprising a liner extending inwardly of said first named container :from its convex shaped end wall and coacting with the concave shaped end wall of said adjacent container to define first and second spaced apart and oppositely directed jet forming cavities in the explosive material conta-ined within the two containers, said liner defining `a hollow standoff chamber extending axially of said lfirst named container and having opposed ends `one `of which opens to vthe concave shaped end wall of said adjacent container so that the latter end wall cooperates with the liner `to define said first jet forming cavity, said liner also being shaped `to define Isaid second jet forming cavity fat the other end of 'and directed into said ystandofi` 'chamber and extending into the explosive material in said first name-d container.

3. An explosive cartridge adapted for alignment with y -other identical cartridges toform an elongated cofurnn of explosives, comprising a substantially cylindrical container for explosive material, one end of said container being provided with a concave, conically shaped end wall and the other end of said container being provided lwith a convex conically shaped end wall having t-he ysame cone angle as lsaid concave shaped end wall, 'the convex `shaped end wall of said container being shaped and ldimensioned to coact with the concave shaped end wall of an adjacent identical container to ybring `the two Y a liner extending inwardly of Isaid first named container lfrom its convex shaped end wall and coacting with the concave shaped end wall of adjacent container to define first and second spaced apart :and oppositely direct-ed jet forming cavities in `the explosive material contained Within lthe ltwo containers, said liner defining a hollow cylindrical standoff chamber extending axially of and concentr-ic with said first-named container, sai-d chamber having opposed ends, one of which opens to the concave shaped end wall of said adjacent container so that the latter end wall cooperates with the lin-er to define said firs-t jet for-ming cavity which is conically shaped and has its apex aligned with the axis of said chamber, said liner also hav- I ing a conically shaped portion at the other end of said standoff chamber defining said second jet forming cavity which is directed into the standoff chamber and extends into the explosive material in said first-named container, the apex of said conicallyshaped liner portion being sembled into a column, and structnral means comprising aligned with the axis of said standoff chamber and with References Cited in the le of this patentV UNITED STATES PATENTS Muskat et al. Jan. 10, 1950 Klotz July 13, 1954 FOREIGN PATENTS 20,110 Great Britain of 1911 999,974 France Oct. 10, 19511.v 851,474

Byers: Pit and Quarry, vol. 42, No. 5; page 99 (1949).

(Copy in Scienu'c Library.)

Germany l ct. 6,A 1952