US2789504A - High explosives - Google Patents

Description

April 23, 1957 'D. BQMQCLOUD ETAL HIGH EXPLOSIVES 2 Shee'ts-Sheet 1 Fil ed Feb. 25. 1950' mvamoas DON B. McCLOUD 8\ MARY v McCLOUD f g m 1/. Eu;

THEIR ATTORNEY April 23, 1957 o. BJMGGLOUD-ETAL 4 9 HIGH EXPLOSIVES Filed Feb. 25, 1950 asheet -sh et 2 INVHVTOR. DON B. McCLouo &

MARY McC-Loun' THEIR ATTORNEY United States Patent ice HIGH EXPLOSIVES Don B. McCloud and Mary McCloud, Carbondale, 111.; said Don B. McCloud assignor to said Mary McCloud This invention relates to high explosives, more particularly those employing liquid oxygen impregnated carbonaceous material, encased in cartridges, and which are adapted for use in blasting operations where very hard materials such as rock, ore, and the like, are encountered. This application is a continuation in part of the copending application of Don B. McCloud and Mary Mc- Cloud, Serial Number 776,068, filed September 25, 1947, now abandoned, and entitled High Explosives.

Liquid oxygen explosive consists of porous, combustible materials saturated with liquid oxygen, and for brevity known as LOX. In the past, this explosive has been prepared by packing a porous type of carbon such as lampblack in a cloth bag with an expansible liner or stiffener inside the bag, then saturating the bag and contents by immersion in liquid oxygen. The porous carbon within the bag absorbs or adsorbs approximately three and one-half times its weight of liquid oxygen and such carbon-oxygen mixture constitutes the high explosive known as LOX. The bag of carbon is commonly called a cartridge and after saturation is called a saturated cartridge.

Heretofore, the outside diameter, and the elongated shape of an LOX cartridge, has been governed by the size and shape of a cloth bag used as an outer covering. An expansible sheath, or liner, when used inside of the cloth bag,has given a certain amount of longitudinal rigidity to a cartridge, but in every case the outer cloth covering or bag has been the means of retaining the porous, combustible ingredients within the cartridge, and

such cartridge bag has been free to expand radially to its full elastic limit. It is necessary to pack or compress the porous, combustible ingredients to certain densities within the retaining medium of a cartridge so as to accomplish the desired carbon-oxygen ratio when a cartridge is saturated, and inasmuch as the cloth bag constitutes the retaining medium in all previously made cartridges, the size and the shape of thecloth bag determines the size and the shape of the cartridge. The most'widely used filter for cartridges is a type of pure lampblack that is exceedingly soft andfiuify in its natural state. When such a filter is compressed in a cartridge, considerable tension is, exerted on the cartridge bag which tends to bulge and stretch to its expansible limits. As a result of this, it has been impossible to manufacture cartridges of uniform, precise outside dimensions on a commercial basis. A type of cotton fabric known as osnaburg is uni-' versally used for cartridge bags, and these bags are made by folding a piece of cloth cut to suitable size and then sewing together one side and one end of the folded material. A slight deviation in the bag seam, a change in the fibres or weave of the cloth that might influence its stretching characteristics, or a change in' the pressure required to compress the carbon content of a cartridge to its required density, cause variations in the diameter, size and shape of cartridges. The prohibitive cost of heavy, non-stretchable fabric cut and sewed with great 110-" 2,789,594 Patented Apr. 23, 1957 curacy, prohibits the commercial use of bags of this latter yp It is also common practice in the industry to store cartridges in bins with one row of cartridges stacked upon another to a considerable height. Cartridges in the bottom layers of such a pile tend to lose their cylindrical shape due to the pressure on them when a flexible cloth bag is the shaping element.

LOX cartridges of precise and uniform outside dimensions are of great importance in modern blasting operations because of the comparatively recent development of so-called precision drilling of vertical blast holes into which the explosive is charged. Such holes formerly were drilled by means of a churn type drill that produced a hole through raising and dropping a heavy cylindrical shaped tool terminating in a rock cutting bit. Blast holes drilled in this manner often were irregular and hole diameters were not uniform in various types of earth and rock formations, and there was nourgent necessity for precise shape and dimensions of the cartridges. Comparatively recently, however, rotary drills, similar to those used for oil well drilling, have been adapted for blast hole drilling. These rotary drills produce smooth, straight blast holes of uniform diameter.

It is advantageous from a blasting standpoint to allow as little clearance as possible between explosive cartridges andthe wall ofthe blast hole in which the cartridges are charged. Blast holes of precise, uniform diameter make it necessary to have similar precision and uniformity in cartridge diameter in order to get maximum results from blasting, and one phase of our invention is directed to this purpose, as will be more fully pointed out hereinafter.

Moreover, for the past several years, engineers and scientists, have been investigating the peculiar phenomenon exhibited by certain high explosives known as the Munro effect. It has been demonstrated that the shape of an explosive charge sometimes controls to a large extent the direction in which a major amount of the forces are exerted when detonation occurs. It has also been demonstrated'that by shaping the end of an explosive charge in the form of a hollowed-out cone, it is possible to have much of the explosive force directed away from such end, in a so-to-speak jet of explosive force. This principle was widely used during the recent war in the development of explosives known as shaped charges. These shaped charges were used to drill holes in enemy pill boxes. The famed bazooka shell was a missile holding a shaped charge that would drill a hole through the steel shell of an armored vehicle. These are known examples of the peculiar jet-like forces that emanate from a properly shaped, hollowed-out surface of a high explosive. In usual mining or quarrying blast, holes are drilled into therock at suitable intervals and to suitable depth after which the holes are charged with explosive. Each loaded or charged hole is actually a column imbedded in the rock. Ordinarily, upon detonation, the explosive charge in each blast hole, exerts its principal forces laterally in all directions. By utilizing this so-called Munro effect in a manner more fully set forth hereinafter, instead of the even dispersion of the explosive energy as now produced, the explosive force of a blasting cartridge, individually, or in a column of cartridges, is concentrated and focused in radial sheet-like zones, which will shatter or fragment the rock or the surrounding material of a blast hole on a much wider radius than was thought possible.

It is a general object of our invention, therefore, to provide a cartridge, especially one containing liquid oxy- I gen-lampblack, which takes and retains a precisely acsnug disposition in accurately drilled blast holes, and

A still further object of the inventionis to provide 'a liquid oxygen cartridge or container which comprises an' accurately cut blank of relatively stiff non-elastic fibrous material, shaped about a mandrel toa true cylinder of the desired diameter, and the meeting edges fixed to preserve the exterior dimensions, the blank also being provided with shaped tongue accommodated in a conical cap secured to the tongues, and having an easily ap' plied end closure applicable after filling, and in which the securing means of the closure provide a handle ex tension.

Another object of the invention is to provide a high explosive charge, which preferably takes a cylindrical formation, whether it be of the liquid-oxygen lampblack type, or of a shaped or moulded type containing other explosive ingredients, which has impressed or formed in its exterior surface a plurality of spaced grooves or slots, formed to produce the Munro effect, along each groove or slot upon detonation of the cartridge.

Still another object of the invention is to provide in the liquid oxygcn-lampblack type of the explosive, and other types as well, the Munro effect grooves, which are impressed and retained in the explosive material through the formation of the cartridge itself, and wherein the cartridge is of the type which takes and retains the configuration and dimensions necessary for ready insertion into accurately drilled blast holes.

Still another object of the invention is the provision of cartridges of the type referred to, which may be dropped one after the other into a blast hole and wherein the Munro effect grooves assume a haphazard alignment longitudinally, and deliver the Munro effect substantially to any portion of the wall of the blast holes sur rounding the superposed cartridges.

In order to obtain the Munro effect" the grooves must have certain characteristics. ordinarily defined by a pair of flat side walls which meet at an apex and the angle at this apex should be no greaterth'an ninety degrees and no less than fortysfive degrees. Thus, the permissible range of the angle at the apex is from forty-five to ninety degrees.

Another feature which is of critical importance is the ratio of the distance from the axis or center of'the charge to the apex of any groove as compared to the distance across the mouth or open side of the groove. The dis tance from the center to the apex of the groove must .be at least one and one-half times the distance across the mouth of the groove and no greater than three times, the distance across the mouth of the groove.

An important object of the present invention is to pro.- vide a cartridge of the general character above indicated which is of generally cylindrical formation having longitudinal grooves in the cylinder surface and which grooves fulfill the specifications above outlined. V.

In order for the cartridge to have the Munro effect, it is also essential that the explosive be. of a closely compacted nature. A liquid-oxygen explosive is entirely satisfactory and any other explosive which might besubstituted therefor must be of a closely compacted nature such as that provided by the explosives which are melted and formed in solid shape.

Certain types of commercial blasting, portiens reguireg Each. of these grooves" is that the explosive force be downwardly directed over a wide area.

In view of this condition a furtherobject is to provide an explosive cartridge of the general character above outlined which takes the form of a rectangular block having one face formed with grooves having the characteristics above outlined and which grooves will impart to the cartridge the shaped charge effect. In use such a cartridge is placed with the grooves faced downwardly in engagement with the surface which is to be shattered. These grooves will result in a shaped charge effect giving high penetration and good shattering effects.

Other and. further objects of the invention-will appear from the specification and claims hereinafter following, and from the accompanying drawings forming a part hereof, and in which:

Figure 1 is a side elevational view of the completed high explosive cartridge forming the subject matter of the invention.

Figure 2 is an enlarged transverse sectional View, corresponding substantially to the line 2-2 of Figure 1.

Figure 3 is a transverse sectional view of the explosive charge, similar to Figure 2, but shown with the cartridge or casing omitted.

Figure 4 is a plan view of the blank from which the body portion of the cartridge is constructed.

a Figure 5 is a sectional view through the blank shown in Figure 4, and corresponding substantially to the line 5'--.-5 of Figure 4.

' Figure 6 is a plan view of a blank from which the nose portion of the cartridge is constructed.

Figure 7 is a perspective view of the blank shown in Figure 6 in its assembled condition.

Figure 8 is a diagrammatic view illustrating one limit of the permissible range as to the angle at the apex of the grooves and the ratio between the distance from the center to the apex of a groove to the distance across the mouth of'a groove.

Figure 9 is another diagrammatic view bringing out the other limit as to the angle of the apex of the grooves and the ratio above identified.

Figure 10 is a cross section through a modified form of cartridge; and

Figure 11 is a diagrammatic view of the charge shown in Figure 10.

As shown in the drawings, the embodiment of the invention comprises a blank 10 of predetermined length and breadth,rhaving side marginal edges 11 and 12. At one end the blank is provided with a plurality of triangular tongues 13, and the blank 10 is slightly scored along the base, portions of the tongues 13, as at 14, to enable the tongues 13 to be readily bent inwardly'toward' each other for a purpose which will presently appear. The opposite end of the blank 10 is cut offsquare with thesides 11' and 12,-as indicated at 15. Fixed to one face of the. blank 10, as by suitable adhesive, is a corrugated sheet or liner 16, the corrugations 17 of which are disposed longitudinally of the sheet and of the blank 10. The corrugations'17 preferably extend the full length of the blank 10, and at one set of ends terminate at the line of scoring 14, the opposite ends of the corrugations 17 terminating flush with the opposite end 15 of the blank 10. The corrugated sheet 16 also terminates short of theouter edge of the marginal portion 11 of the blank 10, and a greater distance from the outer edge of the marginal portion '12 of the blank 10. In crosssection the corrugations 17 are triangular in shape, the crests 18 thereof being uniformly spaced apart, and defined between-the crests 18, are valleys or grooves 19, the walls-2t) of which diverge outwardly toward the crests 18. I The: blank 10 and the attached corrugated sheet or lininglfi, may bemade of heavy kraft paper, chipboard, strawboard, plastic, or any other sheet material having the necessary strengthand inelasticity.

As before pointed out, the blank,.10 andthelcormgated sheet ,16 are of predetermined .dimensions,- dependent sees-ear upon the diameter and length ofthe cartridgeto'be c'onstructed. The blank 10, with its attached corrugated sheet or liner 16, is adapted to be disposed about a cylindrical form or mandrel (not shown) of exact pre-determined dimensions, so that the blank may be wrapped about the form or mandrel, with the liner 16 inside, until the opposite side edges of the sheet 16 meet and abut, while the marginal portions 11 and 12 of the sheet 10 will be overlapped. The margins 11 and 12 are then secured by suitable metallic clips or fasteners 21, thereby fixing the outside diameter of the body portion 22 of the cartridge 23, and disposing the corrugations 17 side by side continuously around the insidediameter of the cartridge 23. Upon removal of the formed or shaped cartridge cylinder from the mandrel, it will present a continuous inelastic wall held against expansion by the metallic fasteners 21.

In this condition the tongues 13 may be bent inwardly along the scoring 14, to define a conical nose portion adapted to be accommodated within a cone-shaped nose piece 24, secured to the tongues 13 by fasteners 25. The nose piece 24 is preferably made up from a blank 26, of suitable inelastic material similar to that constituting the body portion 22 of the cartridge 23. As best shown in Figures 6 and 7 the blank 26 is preferably in the form of a cutout disk, cut out, as at 27, to define a tongue 28, and a slit 29, so that when the blank 26 is rolled up, the tongue 28 may be inserted into the slit 29 and locked in the slit to maintain the blank 26 in hollow conical shape,

adapted to overlie the tongues 13, and to be secured to the tongues 13 by the fasteners 25.

The cartridge 23 is now ready to be filled with carbonaceous material, in this embodiment, a particular grade of larnpblack such as that heretofore referred to. The

lampblack is introduced into the open rear end of the cartridge 23, and being of a loose powdery character, flows into the cartridge 23 and in and about the corrugations 17, and afterward, being tamped or pressed within the cartridge, the shape of contour of the corrugations 17 are impressed in the exterior surface of the charge in the form of longitudinally extending slots or grooves of triangular formation. When completely filled and packed, a closure 30, in the form of a disk, may be inserted within the rear end of the cartridge 23, and a strand of Wire 31 extended through the wall of the cartridge in position to overlie the closure 23 and hold it in place. The ends of the wire 31 may be extended, and interwound, to form a handle .32 bywhich the cartridge 23 maybe readily carried.

The cartridge 23, when thus assembled and fully packed, r

is" immersed in liquid oxygen for a pre-determined petied, and to facilitate or hasten the impregnation of the carbonaceou material Within the cartridge by the liquid oxygen, the body portion of the cartridge is provided with a plurality of pin holes 33 of extremely small size, of the order of the interstices between the fibres of a woven fabric.

1 The charge'of explosive, proper, shown in Figure 3 apart from the cartridge itself, has an elongated body portion 34, generally cylindrical in shape, and its exterior surface is "characterized by a plurality of longitudinally extending grooves or slots 35, spaced apart by the intervening defining ridges or crests 36, each groove or slot 35 having walls 3737 which extend from a point below the exterior surface of the charge, in divergent relation toward the exterior surface of the charge, thus providing a, plurality of extended cavities or depressions, which upondetonation of the charge, exert the so-called Munro e ife'ct in a plurality of longitudinally extending radially directed zones of concentrated or intensified explosive effect. In this connection, it will be clear that though the charge proper, described in connection with Figure 3, requires the cartridge 23 to retain the same in unitary formation, nevertheless the invention contemplates the formation of"a""charge from other explosive ingredi nts; which may be molded or otherwise formed to provide a] unitary charge, characterized by the slots or grooves already referred to, and which produce the so-called- Munro effect upon detonation of the charge.-

corrugation is represented at c and the'distance from the apex a to the center or axis of the cartridge which is depicted at o is represented by d. In Figure 8 d is three times as great as c which is one limit for this ratio.

' In Figure 9 the reference characters a, b, c, and -d depict the same elements that are illustratedin Figure 8. However, in Figure 9 the angle b is forty-five degrees which is the smallest permissible angle.

Moreover, d is one and one-half times 0.

Briefly summing up at this point, his noted that the, angle bhas a permissible range of from forty-five to ninety degrees. Moreover, d must be from one and one. half to three times as great as c.

Referring to Figures 10 and 11, a modified form of the invention is therein illustrated. The charge is shown as being of generally rectangular formation including an upper face 40, a lower corrugated face 41, and side faces 42 and 43. These faces are preferably defined by a. cardboard casing or one of comparable material which encloses therewithin the explosive material represented at" 44. This material is preferably the carbon which is saturated with liquid oxygen. cludes a plurality of corrugations 45 which are in all respects similar to the corrugations 17 in the form of Figure 2.

As shown in Figure 11, the angle at the apex of one of the corrugations 45 is represented at e. The distance across the mouth of one of the corrugations is indicated at g and the distance from the apex to the face 40 is indicated at f. In accordance with the principle abo've explained, the angle e has a permissible range of fortyfive to ninety degrees and the distance f must be from one and one-half to three times the distance g.

The explosive charge shown in Figure 10 is intended to be used by placing the corrugated face 41 downwardly and in engagementwith a surface to be shattered. Upon detonation the corrugations 45 give the shaped charge effect which results in greatly improved penetrating effects.

- Through the arrangement described, the high explosive cartridge is provided having a constant pre-determined diameter before and after filling and packing and after. saturation with liquid oxygen, rendering the same suitable for insertion into accurately drilled blast holes, and by reason of the formation of the charge itself, upon detonation, the charge of explosive will exert the so-called Munro effect radially in a plurality of extended zones. Additionally, When the cartridges are packed haphazardly' one on top of another in a blast hole, the column of explosive will exert its effect upon the wall of the blast hole radially in all directions.

Although the preceding description of the invention has been directed to explosives and explosive cartridges of cylindrical formation, and consequently of the type most used in commercial blasting operations, the invention ob: viously is not limited to cylindrically shaped explosivecharges or explosive cartridges. Sometimes explosive charges are used to break boulders by a method known in the mining industry as mud capping," adobe blasting or bulldozing, which consists in placing an explosive charge on the surface of a boulder, covering the charge with mud or dirt, and then detonating the charge. The force of the explosion that strikes the surface of the boulder often is sufi'icient to break the boulder into pieces In Figure 8 this angle b The corrugated face 41 in-,

agree- 50a qf-asize--which mayreadily be handled. For this type of blasting an explosive chargewhich will present a flat surface next to the boulder would -bemore eifeetive than a cyli-nd rically shaped charge, because the explosive force emanates from the surface of the charge.

Thus in one adaptation of the invention the explosive charge would he of elongated box-like form, rectangular instead of circular in cross section, and encased in a boxshaped ribbed cartridge, similar to the cartridge 23, with the projections or ribs inwardly disposed. In packing such a cartridge, itmay be placed in a form to prevent distortion when carbonaceous material is compressed Within it to the proper density, and after removal satu-' rated with liquid oxygen. The explosive charge within the container; will thus comprise a rectangular block having V-shaped grooves like the groove 35, along each flat surface, other than the ends, which will give directional force to the energy released bythe explosion in a manne'r" already referred to. In addition to cylindrical and box-like shapes mentioned, other shapes might be used, but in each case the explosive will include a plurality of \f-shaple'd slots or grooves of the character already described in detail.

While we have illustrated and described the preferred form of-construction for carrying our invention into effct, this-is capable of variation and modification without departing from the spirit of the invention. We, therefore,do not wish to be limited to the precise details of construction set forth, but desire to avail ourselves of such variations and modifications as come within the ease of the appended claims.

What is claimed is: I j

w 1. An explosive charge of generally cylindrical formatioii having longitudinally extending closely adjacent corriigat ions formed in its periphery, said corrugations being defined by grooves having side walls which meet at apices and open mouths with the side wall of one groove meeting. the side wall of the next adjacent groove, the an'gle'between the side walls at each apex ranging from forty-five to ninety degrees and the distance from the center of s'aid charge to each apex being from one and one-half to three times the distance across the mouth of one of the grooves, said explosive charge being of a closely compacted homogeneous explosive material having high detonating properties.

2. An explosive charge of generally cylindrical formation having a plurality of longitudinally extending closely a'djacent corrugations defined by a plurality of grooves with each groove" being of substantially the same size and snapeas any other groove, each of said grooves having a pair of side walls which meet at an apex and an open mouth with the side walls of every groove meeting the walls'of the next adjacent grooves, the angle between the side walls at each apex ranging from forty-five to ninety degrees and the distance from the center of said charge to each apex being from one and one-half to three times the distance across the mouth of one of the grooves, said explosive charge being of a closely compacted homogeneous liquid oxygen explosive material having high detonating properties.

3. A liquid oxygen explosive charge of generally cylifidrical formation having longitudinally extending closely adjacent corrugations formed in its periphery, sai'clcorrugations being defined by grooves having side walls meet at apice's and open months With the side walls of every groove meeting the side walls of the urea adjacent grooves, the angle between the side walls zit-each apex ranging from forty-five to ninety degrees andthe distance from the center of said charge to each apex being from one and one-half to three times the distance acrossthe mouth ofoneofi the grooves, and a cylindrical casing enclosing said charge with said corruga tionsin engagement withthe inner face of said casing.

4. A detona-ti ng. explosive charge of generally cylindrical formationhaving. a plurality of longitudinally extending closely adjacent corrugations defined by a plurality of grooves with each groove being of substantially the same size andshape as any other groove, each of saidgrooveshaving a pair of side walls which meet at an apex and an open mouthwit-h: the sidewalls of every groove meeting the side walls of the next adjacent grooves, the angle between the side walls at each apex ranging from forty-five to ninety degrees and the distance from the center of" said charge to each apex being from one and one-half to three times the distance across the mouth of one of the grooves,.s'aid' explosive charge comprising carbon saturated with liquid oxygen to provide a closely compacted mass. 1

5. In combination, an outer cylindrical casing, an innor casing having corrugations engaging. the, inner face of said' ou't'er casing, said corrugations being defined by longitudinally extending grooves with all of the grooves of substantially the same size and shape each of said grooves having side Walls which meet at an apex and an opeh'rhouth with the side walls of every groove meetingthe' sidewalls of the next" adjacent groove, the angle between the side Walls at said' apex ranging f om fortyfive to" many degrees and the distance from said apex to the center ofsaid' inner casing being from one and onehalf to three time's-the distance across the mouth of one of'th'e grooves, and a clo's'ely'conipacted homogeneous explosive material having high detonating properties compltely' fillin v said" inner cas'ing.

6. In combination, an outer cylindrical casing, an inner casin'ghaving corrugations engaging the inner face of said outer casing, s'ai'd' corrugations being defined by longitudinally extending grooves with all of the grooves of substantially the same size and shape, each of said grooves having side walls which meet at an apex and an open mouth with the side walls of every groove meeting the side walls of the'next adjacent groove, the angle between the sidewalls at said apex ranging from forty-five to ninety degreesand the distance from said apex to the center of said inner casing being from one and one-half to three times the distance across the mouth of one of the grooves, and carbon saturated with liquid oxygen completely filling said inner casing.

References Cited in the file of this patent UNITED STATES PATENTS 1,923,496 McCloud m; Jan. 1, 1935 2,409,343 Grenlick r Oct. 22, 1946 2,494,256 Musket et a1. Jan. 10, 1950 2,543,057 Porter Feb. 27, 1951 FOREIGN PATENTS 369,237 Italy Mar. 15, 1939 579,279 Great Britain July 30, 1946 921,405 France Jan. 13, 1947 618,617 Great Britain Feb. 24, 1949 622,062 Great Britain Apr. 26, 1949 OTHER REFERENCES Sukha'revsky: VoinaiTekhnika,'vol. 253 (1926),.No. 39, pages 18 to 24 and 8 sheets of drawings. (Copy in Div. 70.) Unofiicial translation available in Div. 70 (16 pages of text and same 8 sheets of drawings).

Birkhotf et al.: Journal of Applied Physics, vol. 19, No. 6, pages 563-582, particularly page 565 (June 1948). (Copy in Scientific Library.)

Images