US3837279A

US3837279A - Blasting cartridge and primer

Info

Publication number: US3837279A
Application number: US00337934A
Authority: US
Inventors: H Cooke
Original assignee: EI Du Pont de Nemours and Co
Current assignee: ETI EXPLOSIVES TECHNOLOGIES INTE
Priority date: 1973-03-05
Filing date: 1973-03-05
Publication date: 1974-09-24
Anticipated expiration: 1991-09-24

Abstract

A blasting cartridge comprising a tube of plastic film filled with water-bearing explosive and gathered and closed at both ends has a sleeve or capsule over one or both ends, or a full-length sheath, e.g., of water-resistant paper or plastic, which forms an end abutment surface at one or both of the package ends that impedes cartridge override and jamming during string-loading of boreholes. A primer comprising a blasting cap embedded in this cartridge has the added advantage of improved integrity when punctured for the reception of the blasting cap.

Description

United States Patent 11 1 1111 3,837,279

Cooke, Jr. [4 Sept. 24, 1974 BLASTING CARTRIDGE AND PRIMER FOREIGN PATENTS OR APPLICATIONS Inventor: 5 Cooke, Pineville 794,623 9/1968 Canada 102/24 a. [73] Assignee: E. I. duPont de Nemours and Primary Examiner-Vern" Pendegrass Company, Wilmington, Del. TRA [22] Filed: Mar. 5, 1973 [57] ABS CT A blastmg cartridge compnslng a tube of plast1c film PP NOJ 337,934 filled with water-bearing explosive and gathered and closed at both ends has a sleeve or capsule over one or [52] Us. CL 102/24 R both ends, or a full-length sheath, e.g., of water- [51] Int Cl. "F42b 3/02 resistant paper or plastic, which forms an end abut- [58] Field l' i 102/24 R ment surface at one or both of the package ends that impedes cartridge override and jamming during stringloading of boreholes. A primer comprising a blasting [56] SXF SZ cap embedded in this cartridge has the added advantage of improved integrity when punctured for the re- Duesing of the cap 3,200,743 8/l965 Griffith et al. 102/24 3,332,349 7/1967 Schwoyer et al. 102/24 20 Claims, 3 Drawlng Flgllres PAIENTEB FIG- FIG-

BLASTING CARTRIDGE AND PRIMER BACKGROUND OF THE INVENTION The present invention relates to a blasting cartridge of water-bearing explosive especially adapted to be loaded efficiently in small-diameter boreholes.

Water-bearing explosives, which typically comprise an oxidizing component and a fuel component dispersed or dissolved in an aqueous medium that normally is thickened or gelled, currently are available in the form of small-diameter cartridges for use in underground blasting operations. The cartridge is a tube of plastic film, filled with explosive, and gathered at both ends and closed, e.g., by means of metal closure bands around the gathered portions. Such cartridges, while performing very satisfactorily when properly loaded into the borehole, often are difficult to load by means of certain commonly used loading techniques.

One efficient borehole loading technique is the string-loading technique whereby several cartridges are pushed into the hole, e.g., by means of a pole, at the same time in the form of a composite multi-cartridge unit or column. This technique is advantageous in that it is faster than a cartridge-by-cartridge loading procedure, and it avoids the possibility of cartridge column separation due to dust which can occur when the cartridges are loaded singly. However, the film-wrap, water-bearing explosive cartridges available in the art for use in underground blasting, which generally range from about 7/8 inch to about 1 3/4 inches in diameter, cannot be loaded consistently in a trouble-free manner by the string-loading procedure. Cartridges of this type, when pushed into the borehole as multi-cartridge units, i.e., units of two or more cartridges, tend to become wedged in the hole as a result of cartridge over-ride, especially in the case of rough-walled holes or when the borehole diameter exceeds the cartridge diameter, e.g., by one-quarter inch or more. Inasmuch as the wedged mass of cartridges can produce a bridge in the cartridge column or a void at the back of the borehole, which can result in poor blasting performance, it is necessary to resort to a less efficient method of borehole loading, i.e., the movement of only one cartridge toward the back of the hole at a time.

Apart from the problem of jamming during stringloading, the currently available cartridges described above, in practically acceptable film wrap thicknesses, also may afford problems related to lack of package integrity under certain handling conditions. For example, the buckling and tear resistance of the cartridge may not be sufficient to withstand the poling force used during loading, especially when the borehole is rough and gravelly. Also, puncturing a primer cartridge for insertion of a blasting cap may result in the propagation of the tear in the film and loss of the integrity of the cartridge.

SUMMARY OF THE INVENTION This invention provides an improved blasting cartridge of water-bearing explosive comprising (a) a tubular member made of pliable film material, e.g., a polymeric linear terephthalate ester, the tubular member i) being gathered and closed at both ends, e.g., by means of encircling closure means such as a metal band or clip, and (2) containing a water-bearing explosive in an amount sufficient to produce a tubular package having a substantially uniform cross-section portion and tapered end portions continuous therewith; and (b) at least one water-resistant hollow cylindrical member. e.g., a plastic or coated-paper end sleeve, or preferably a single end-to-end sheath, circumferentially disposed around, and stationarily engaged with, the package at the uniform cross-section portion thereof and extending at least about as far as one or both of the tapered portions, the cylindrical member forming a circularly bounded end abutment surface, e.g., an annular surface, on the package, the abutment surface having an effective diameter at least about equal to that of the uniform cross-section portion of the package, and the stiffness of the cylindrical member and the position and attitude of the abutment surface relative to the tapered portion of the package being such that when said cartridge is positioned coaxially with its end abutment surface in contact with the end of another like cartridge, a compressive force applied axially to the pair of contacting cartridges causes cartridge lodgement against the end abutment surface, thereby impeding substantial relative motion of the cartridge.

The invention also provides a primer comprising the blasting cartridge of the invention and a blasting cap embedded within the water-bearing explosive therein and disposed within a perforation in the film material located in the portion of the package around which the cylindrical member is circumferentially disposed or in the tapered end portion of the package to which the cylindrical member extends, the cylindrical member preferably being of sufficient length that the cap embedded in the explosive is located substantially totally within the confines of the cylindrical member.

BRIEF DESCRIPTION OF THE DRAWING FIGS. 1 and 2 are longitudinal cross'sectional views of two different embodiments of the blasting cartridge of the invention; and

FIG. 3 is a longitudinal cross-sectional view of a primer of the invention.

DETAILED DESCRIPTION In the blasting cartridge of this invention, a waterbearing explosive composition is enclosed in a tubular film package which has a sheath or jacket, or one or more sleeves or capsules, fittedaround it and adapted to provide, at one or both ends of the package, an abutment surface against which an adjacent cartridge will become lodged during borehole loading so as to prevent cartridge override. Because of the film wrap, the package wall is impermeable to seepage from within, and the cartridge has good dimensions] stability owing to the fact that tight packing of the explosive can be achieved with a film package gathered and mechanically closed at both ends. In contrast to the waterbearing explosive cartridges of the prior art, the cartridge of the invention has an end abutment surface, e.g., the annular surface of a projection or shelf formed by the end of a stiff sheath or sleeve, which surface is about as large in effective diameter as the uniform cross-section portion of the package, and this feature permits the cartridge to be string-loaded in a borehole without difficulty. The cartridge design also is more favorable with respect to resistance to tear propagation in a primer cartridge which is punctured for the reception of a blasting cap, and the preferred cartridge, wherein a single cylindrical member extends to both end portions of the package, additionally has the buckle and tear resistance needed to withstand high loading forces coupled with a high degree of borehole wall resistance.

The tubular member from which the package is formed is filled, or nearly filled, with a water-bearing explosive, and the ends of the tubular member are constricted, or gathered, and closed, thereby forming a tubular package of substantially uniform circular crosssection between, and continuous with, tapered end portions. Such a package can be made, for example, using packaging machinery such as that described in US. Pat. No. 2,831,302, issued Apr. 22, 1958, to Oscar Mayer and Co. The tubular member and package are made of pliable film material, e.g., a polymeric linear terephthalate ester such as polyethylene terephthalate, polyethylene, cellophane, a vinyl polymer, etc. Polyethylene terephthalate film is preferred because of its resistance to creep, ease with which it can be intentionally slitted for tamping, etc. Polyethylene terephthalate should be in a biaxially oriented, heat-set form as described in US. Pat. No. 2,830,735, issued Jan. 21, 1958, to L. E. Amborski. When polyethylene terephthalate film is used to form the package, the continuous longitudinal seam which is made in the advancing tube in the apparatus described in the aforementioned US. Pat. No. 2,831,302 can be made by the method described in co-pending, co-assigned US. Pat. Application Ser. No. 281,165, filed Aug. 16, 1972, by W. .1. Simmons.

At least one hollow cylindrical member is circumferentially disposed around the package, the cylindrical member(s) being disposed around the uniform crosssection portion of the package and extending at least about as far as one, or preferably both, of the tapered end portions. The endmost portion of the cylindrical member forms a peripheral abutment surface on the end portion of the package, the abutment surface being a substantially circularly bounded surface having an effective diameter equal to at least about the diameter of the uniform cross-section portion of the package. In the simplest case, the cylindrical member is a uniformdiameter tube having substantially flat annular end surfaces, and the abutment surface can be an annular end surface of such a cylindrical member, which surface lies in a plane that is substantially normal to the longitudinal axis of the tubular member. The abutment surface need not be flat or annular, however, as will be discussed hereinafter. As will be seen from the accompanying drawing and the discussion which follows, the exact contour of the abutment surface and the position of this surface with respect to the adjoining package surface can vary, provided that the effective, i.e., outermost, diameter of the abutment surface is at least about equal to the diameter of the uniform cross-section portion of the package, i.e., larger than the diameter of the tapered portion of the package. To assure proper abutment of cartridge ends, the cylindrical member generally should extend to, and the abutment surface lie in, a plane which bounds, or falls outside the boundaries of, the uniform cross-section portion of the package, this plane being substantially normal to the longitudinal axis of the tubular member. The degree of rigidity or stiffness of the cylindrical member is sufficiently high that the effective diameter of the abutment surface does not become substantially reduced as a result of the abutment under an axially applied compressive force.

Such reduction would amount to a tapering of the abutment surface with the attendant possibility of cartridge over-ride during axial motion.

Referring to FIG. 1, which shows a blasting cartridge of the invention wherein two separate sleeves are dis posed around the film package, one at each tapered end, a tubular package 1, filled with water-bearing explosive 2 and formed from a tubular member of pliable film having gathered

ends

3 and 4, held closed by

encircling closure members

5 and 6, respectively, has a substantially uniform circular cross-section portion 10 between, and continuous with, tapered end portions lb and 1c. Two like hollow cylindrical members, 7 and 8, e. g., plastic, or waxed or plastic-coated paper tubes, are circumferentially disposed around package 1 and stationarily engaged therewith, e.g., by friction fit, cylindrical member 7 extending to tapered portion 1b and cylindrical member 8 to tapered portion 1c. The outermost end surfaces of cylindrical members 7 and 8, which lie in planes that bound uniform cross-section portion 1a, formed peripheral abutment surfaces and 8a, respectively.

Abutment surfaces

7a and 8a are annular (i.e., circularly bounded) and substantially flat, and lie in planes that are substantially normal to the longitudinal axis of package 1. Cylindrical members 7 and 8 are of uniform diameter, and therefore the outer or peripheral (i.e., the effective) diameter of surfaces 70 and 8a equals the outer diameter of cylindrical members 7 and 8. The end portions of cylindrical members 7 and 8 of which abutment sufaces 7a and 8a are a part thus can be seen to form angular projections, or shelves, around the shoulder portions of package 1 where tapering begins, these projections serving as backstops against the passage of axially adjacent cartridges when an axial compressive force is applied to a column of the cartridges in a restricted passage such as a borehole.

1n the blasting cartridge shown in F IG. 2, a single hollow cylindrical member 9, e.g., a plastic or waterresistant paper tube, is disposed around package 1, extending to planes which fall outside the boundaries of uniform cross-section portion 1a and beyond tapered portions lb and 1c. The portions of cylindrical member 9 which extend beyond the tapered portions 1b and 1c are collapsed so as to form accordian-pleated annuli 10 and 11, respectively, the end surfaces of cylindrical member 9 forming

annular abutment surfaces

9a and 9b, which lie in the same planes as gathered

ends

3 and 4, respectively. In this instance, pleated annuli 10 and 11 form backstop end projections on package 1, tapered portions 1b and It being recessed within pleated annuli l0 and 11, respectively. In this embodiment, although the actual outer diameter of the abutment surfaces can be smaller than that of the uniform crosssection portion of the package, e.g., when the surfaces are in planes passing through trough portions of the pleated annuli, the effective diameter of the surface is intended to denote the diameter at the crest portions of the pleated annuli, such portions in effect acting as the abutment surfaces under compression.

The primer shown in FIG. 3 also has a single hollow cylindrical member 9 disposed around package 1, extending beyond tapered portions lb and 10. In this case, the portions of cylindrical member 9 which extend beyond tapered portions 1b and 1c are uncollapsed, forming straight-walled annuli 12 and 13, respectively, which act as backstop end projections on package 1,

tapered portions 1b and being recessed within annuli l2 and 13, respectively. Blasting cap 14, in this instance an electric blasting cap, is embedded in waterbearing explosive 2, the cap having been inserted through perforation in the film material in tapered portion lb. This primer is adapted for use in bringing about the detonation of other blasting cartridges in a cartridge column.

In order that a surface of the cylindrical member disposed around the film package be adapted to abut with an opposing surface of an adjacent package under an axial compressive force without over-ride, the cylindrical member generally should extend to the boundary plane between the uniform cross-section and tapered portions of the package (or to the shoulder of the package), as shown in FIG. 1, or beyond such plane, as shown in FIGS. 2 and 3. While the position of the cylindrical member shown in FIG. 1 can provide the required backstopping, provided the cylindrical member is sufficiently stiff and the contour of the abutment surface does not conform to the contour of the tapered portions of the package (i.e., the abutment surface preferably forms an angle of at least about 90 with the wall of the uniform cross-section portion of the package), it may be desirable, e.g., for reasons associated with the capabilities of available cartridging machinery, or to provide maximum capability with respect to abutment strength and cartridge integrity, to extend the cylindrical member(s) to locations beyond the boundary planes specified above.

While the exact location of the end of the cylindrical member, and the abutment surface formed therefrom, when extended beyond the shoulder of the package, is not critical, it is preferred that the distance between the abutment surface and a plane parallel thereto tangent, to the nearest surface of the package (normal to the packages longitudinal axis) be limited to assure propagation of detonation from one cartridge to the next in a column of cartridges. The maximum distance between the abutment surface and the aforementioned parallel plane depends on the gap sensitiveness of the blasting agent, desired borehole loading density, etc., but generally will be about l-3 inches. One way to reduce this distance, if desired, is to collapse the extended portion of the cylindrical member, e.g., to form an accordionpleated annulus such as is shown in FIG. 2, or to peripherally fold the end of the cylindrical member thereby producing, in some cases, a substantially closed end over the gathered portion of the tubular member. On the basis of ease of manufacture, the accordion-pleated annulus is preferred over the closedend modification. In closed-end cartridges, the end abutment surface is internal as well as peripheral, the entire closed end surface being the abutment surface in this case. Collapsing of the extended portion(s) of the cylindrical member can be effected in situ, e.g., by using cartridges with uncollapsed extended end portions and crushing the end portions by axial force while loading the cartridges in the borehole, but it is preferred that cartridges having pre-collapsed extended end portions be employed so as to assure that propagation requirements are met. In cases such as those shown in the drawing, the abutment surface of the package is the same as the end surface of the cylindrical member; in other cases, e.g., those in which a circumferential fold is made in the extended end portion of the cylindrical member, the abutment surface is a portion of the side surface of the cylindrical member. Except for the limitation discussed above for the case in which the abutment surface is located at the boundary plane of the uniform cross-section portion of the package, the configuration and attitude of the abutment surface with respect to the side of the package can be as desired, but, considering the relatively small thickness dimension of the cylindrical member and the capability of available cartridging machinery, a more easily achieved, and therefore preferred, abutment surface is one which is substantially flat, and lies in a plane substantially normal to the longitudinal axis of the package.

The blasting cartridge of the invention can have a single cylindrical member disposed around the film package extending to only one end thereof, e.g., an endsleeve (open at both ends, or closed at the outermost end in the form of a capsule), such cartridges being capable of being satisfactorily string-loaded in boreholes with the sleeved end of one cartridge abutting the unsleeved end of the adjacent cartridge, etc. In this case, there is a single abutment surface for each pair of adjacent cartridges, and the unsleeved end of one of the cartridges lodges against the abutment surface of the other. However, greater reliability in the string-loading of end-sleeved cartridges in boreholes is achieved if there is a sleeve at both ends of the package, and cartridges having a sleeve at each end therefore are the preferred end-sleeved cartridges. Cartridges having a single end-to-end cylindrical member around the film package provide maximum reliability, both with respect to ease of string-loading as well as to cartridge integrity, and therefore are the most preferred of the blasting cartridges of the invention. In a column of cartridges having a sleeve at both ends or an end-to-end sheath, there is an abutment surface at the end of both cartridges of adjacent pairs, and each cartridge lodges against he others abutment surface.

The cylindrical member(s) are stationarily engaged with the film package, e. g., by friction fit, a layer of adhesive, etc. This assures that the required position of the abutment surface(s) provided by the cylindrical member(s) is maintained during handling and loading into a borehole. An effective means of obtaining the stationary engagement between the package and the cylindrical member(s) is to use a cylindrical member having a slightly smaller inner diameter than the outer diameter of the uniform cross-section portion of the water-bearing explosive package, e.g., about l/32 of an inch smaller.

The dimensions of the cylindrical member(s) will be selected on the basis of economics, conditions the cartridge is expected to withstand, etc. If one or two end sleeves are used, their length should be at least about equal to, and preferably at least about 1.2 times, the diameter of the uniform cross-section portion of the package. In the primer of the invention, the sleeve at the blasting cap end of the cartridge preferably is long enough that the cap embedded in the explosive is located essentially completely within the confines of the sleeve. This design affords better stability with respect to the cap position in the cartridge, reducing the possibility of the caps exiting from the side wall of the cartridge. If a single end-to-end sheath is employed, its length is at least about equal to the distance between the planes bounding the uniform cross-section portion of the film package, and not so great that the distance between each abutment surface and a plane parallel thereto tangent to the nearest surface of the package (normal to the packages longitudinal axis) causes the gap sensitiveness of the explosive to be exceeded, as discussed above.

The material of construction and thickness of the cylindrical member are such that the member is strong enough to provide and maintain the required abutment surface for an adjacent cartridge to lodge against when the cartridges are subjected to axial compressive force, as in string-loading of boreholes. Thus, the cylindrical member must possess a certain degree of stiffness or rigidity, while at the same time not being brittle or easily shatterable, a condition which could lead to failure of the member during handling or use of the cartridge. At the same time, the cylindrical member should possess sufficient wet-strength that it does not become weakened when subjected to humid storage or wet boreholes to the extent that the abutment surface cannot be maintained. Certain natural papers are suitable materials of construction, e.g., manila and kraft papers, paperboard such as cardboard, etc., suitably treated or coated, where required, to achieve the necessary wetstrength, e.g., coated with a wax or plastic such as polyethylene. Synthetic paper-like sheet materials, e.g., spunbonded olefins, such as high-density polyethylene, and molded or extruded plastics are the best material of construction on the basis of wet-strength, although strong, suitably coated or treated natural papers, e.g., waxed wet-strength kraft paper, may be preferred for economy reasons. The wall thickness of the cylindrical member will depend on the available thicknesses for the material used and the severity of use conditions, sleeves and sheaths usually being at least about 0.005 inch thick. Paper cylindrical members can be convolute-wound or spiral-wound, both types being equally effective.

The particular water-bearing explosive composition contained in the blasting cartridge is not critical, and can be any desired composition. Because the cartridge can be string-loaded satisfactorily, i.e., moved into a borehole as a multi-cartridge unit, and can be subjected to stemming procedures without breakage, the cartridge is especially suitable for use in underground blasting in coal, and accordingly the explosive composition in cartridges intended for this use will be a permissible explosive, e.g., a formulation of the type described in US. Pat. 3,43 1,155, issued Mar. 4, 1969, to C. Dunglinson and W. M. Lyerly.

The primer of the invention has a blasting cap embedded within the water-bearing explosive therein and disposed within a perforation in the film material, the perforation being located either in a tapered end portion of the package to which the cylindrical member extends, as shown in FIG. 3, or in the side wall of the package around which the cylindrical member is circumferentially disposed (a perforation also being made in the cylindrical member wall in this case). Such location of the cap-receiving perforation enables the cylindrical member to prevent any significant propagation of the tear in the film caused by puncturing of the cartridge to produce the perforation. The attitude of the blasting cap in the cartridge is not critical especially since the cylindrical member, in the preferred primer, is long enough that the embedded cap is located essentially completely within the confines of the cylindrical member; thus a cap which is not parallel to the longitudinal axis of the tubular package is prevented by the cylindrical member from exiting from the side wall of the film package. The specific blasting cap employed (type, design, and size) is dependent on the waterbearing explosive composition used and whether an electrical or non-electrical initiation system is desired. Any standard electric or non-electric blasting cap can be employed.

The following examples illustrate various embodiments of the invention, including different blasting cartridge designs and their utility.

Example 1 Twelve-inch-long tubular packages made from a tubular member of biaxially oriented, heat-set polyethylene terephthalate film, 0.0015-inch thick, gathered and closed at each end with a metal clip, contain a waterbearing explosive composition of the class described in the aforementioned US. Pat. No. 3,431,155, the sensitizer component of the composition comprising monomethylamine nitrate. The packages have a 1.25-inchdiameter uniform circular cross-section portion continuous with tapered end portions.

A 1.50-inch long spiral-wound kraft paper sleeve having a 1.25-inch outer diameter and a 0.0l6-inch wall thickness is positioned on each end of six of the above-described packages, the endmost surface of each sleeve being located at the shoulder portion of the package where tapering begins. The tapered end portion of one of the cartridges is punctured and a dummy electric blasting cap is inserted into the cartridge through the puncture. The latter (primer) cartridge retains its integrity after insertion of the dummy cap, the puncture failing to propagate beyond the sleeve. The six cartridges are positioned, primer cartridge first, in end-to-end abutting relationship in a simulated borehole, tce latter being a 1.875-inch inner diameter transparent plastic tube, l0-feet long and containing about a quart of wet sand and gravel distributed along its length, the tube being tilted about 3 below horizontal. Then the column of six cartridges is shoved as a unit toward the back of the hole (end of the tube). The column advances through the tube without cartridge override and jamming, even though considerable resistance to the columns movement is presented by the build-up of gravel ahead of the column. If required, the entire column can be retracted by pulling back on the electric blasting cap wires (the cap having been secured in place in the cartridge by means of two half-hitches). Example 2 Similar results to those described in Example 1 are obtained when the procedure described in Example 1 is repeated with the exception that the paper sleeve is positioned on only one end of each package, the primer cartridge having the sleeve positioned at the end at which the blasting cap is inserted. The six cartridges are positioned in the simulated borehole with the sleeved end of one cartridge abutting the unsleeved end of the adjacent cartridge, etc.

Example 3 The procedure described in Example 1 is repeated with the exception that the sleeves are made of polyethylene and have a 0.030-inch wall thickness. The results are similar to those obtained in Example 1.

Example 4 A full-length sheath of waxed wet-strength kraft paper lb. basis weight plus 15 lb. wax, based on a 3,000 sq. ft. area) is formed and secured around the tubular packages described in Example 1 by wrapping a 12-inch by 4.75-inch sheet of the paper around the package, and applying adhesive between the wrapper and the polyethylene terephthalate film, and also to the wrapper overlap. The end surfaces of the sheath lie in planes which are tangent to the tapered portions of the package normal to the longitudinal axis.

Cartridges having the described full-length sheath are string-loaded in the simulated borehole in columns of nine cartridges without difficulty due to override. Example 5 Similar results to those obtained in Example 4 are obtained when the waxed paper sheath described in Example 4 is replaced by a sheath of 68 pound (per 3,000 sq. ft.) manila paper having a coating of 1.5 mils polyethylene on each side.

Example 6 The cartridges described in Example 4, having a diameter of the uniform cross-section portion of one inch in this case, are string-loaded in 6-7 cartridge columns in 1 7/32 inch diameter, 8.5-9 inch deep boreholes in a limestone formation. Each column of cartridges is pushed to the back of the hole with a l-inch-diameter pole. The primer cartridge in each hole contains an electric delay blasting cap. No wedging of cartridges occurs on loading. After completion of the blasting circuit, the round is fired. Satisfactory breakage is achieved, indicating that the holes had been properly loaded.

I claim:

1. A blasting cartridge comprising a. a tubular member made of pliable film material,

said tubular member being gathered and mechanically closed at both ends and containing a waterbearing explosive in an amount sufficient to produce a tubular package having a substantially uniform circular cross-section portion and tapered end portions continuous therewith; and

b. at least one water-resistant hollow cylindrical member circumferentially disposed around, and stationarily engaged with, said package at the uniform cross-section portion thereof and extending at least about as far as the two planes which bound said uniform cross-section portion and are substantially normal-to the longitudinal axis of said tubular member, said cylindrical member(s) forming two circularly bounded end abutment surfaces on said package, said abutment surfaces having an effective diameter at least about equal to that of the uniform cross-section portion of said package, and the stiffness of said cylindrical member(s) and the position and attitude of said abutment surfaces relative to said tapered portion(s) of said package being such that when said cartridge is positioned coaxially with one of its end abutment surfaces in contact with an end abutment surface of another like cartridge, a compressive force applied axially to the pair of contacting cartridges causes each cartridge to lodge against the others end abutment surface, thereby impeding substantial relative motion of the cartridges.

2. A blasting cartridge of claim 1 wherein said cylindrical member(s) extend beyond one or both of said planes which bound the uniform cross-section portion of said package.

3. A blasting cartridge of claim 1 wherein a single cylindrical member extends at least about as far as both of said planes which bound the uniform cross-section portion of said package.

4. A blasting cartridge of claim 1 wherein two separate cylindrical members are circumferentially disposed around said tubular member, each cylindrical member extending at least about as far as the plane nearest thereto which bounds the uniform cross-section portion of said package.

5. A blasting cartridge of claim 1 wherein said abutment surfaces are annular end surfaces of said cylindrical member(s).

6. A blasting cartridge of claim 1 wherein said cylindrical member(s) extend beyond the tapered portions of said package.

7. A blasting cartridge of claim 6 wherein the portions of said cylindrical member(s) which extend beyond said tapered portions are collapsed so as to form said abutment surfaces.

8. A blasting cartridge of claim 1 wherein the length of said cylindrical member(s) is at least about equal to the diameter of said package.

9. A blasting cartridge of claim 1 wherein said cylindrical member(s) are made of paper.

10. A blasting cartridge of claim 1 wherein said cylindrical member(s) are made of plastic.

11. A blasting cartridge of claim 1 wherein said film material comprises a polymeric linear terephthalate ester.

12. A blasting cartridge comprising a. a tubular member made of pliable film material,

said member being gathered and mechanically closed at both ends and containing a water-bearing explosive in an amount sufficient to produce a tubular package having a substantially uniform circular cross-section portion and tapered end portions continuous therewith; and

b. a water-resistant hollow cylindrical member circumferentially disposed around, and stationarily engaged with, said package at the uniform crosssection portion thereof and extending at least about as far as both of the planes which bound said uniform cross-section portion and are substantially normal to the longitudinal axis of said tubular member, said cylindrical member forming two circularly bounded end abutment surfaces on said package, said abutment surfaces having an effective diameter at least about equal to that of the uniform cross-section portion of said package, and the stiffness of said cylindrical member and the position and attitude of said abutment surfaces relative to said tapered portions of said package being such that when said cartridge is positioned coaxially with one of its end abutment surfaces in contact with an end abutment surface of another like cartridge, a compressive force applied axially to the pair of contacting cartridges causes each cartridge to lodge against the others end abutment surface, thereby impeding the relative motion of the cartridges.

13. A blasting cartridge of claim 12 wherein said cylindrical member is made of paper.

14. A blasting cartridge of claim 12 wherein said cylindrical member extends beyond the tapered portions of said package.

15. A blasting cartridge of claim 14 wherein the portions of said cylindrical member which extend beyond said tapered portions are collapsed so as to form said abutment surfaces.

16. A blasting cartridge of claims 15 wherein the collapsed portions of said cylindrical member are accordion-pleated annuli.

17. A blasting cartridge of claim wherein the collapsed portions of said cylindrical member are peripheral endfolds.

18. An explosive primer comprising a. a tubular member made of pliable film material,

said tubular member being gathered and mechanically closed at both ends and containing a waterbearing explosive in an amount sufficient to produce a tubular package having a substantially uniform circular cross-section portion and tapered 15 end portions continuous therewith;

b. at least one water-resistant hollow cylindrical stiffness of said cylindrical member(s) and the position and attitude of said abutment surfaces relative to said tapered portions of said package being such that when said cartridge is positioned coaxially with one of its end abutment surfaces in contact with an end abutment surface of another like cartridge, a compressive force applied axially to the pair of contacting cartridges causes each cartridge to lodge against the others end abutment surface, thereby impeding the relative motion of the cartridges; and

. a blasting cap embedded within the water-bearing explosive in said package and disposed within a perforation in the film material located in the portion of said package around which said cylindrical member(s) are circumferentially disposed or in the tapered end portions of said package to which said cylindrical member(s) extend.

19. A primer of claim 18 wherein said cylindrical member is sufficiently long that said blasting cap embedded in said explosive is located substantially totally within the confines of said cylindrical member.

20. A primer of claim 19 wherein a single cylindrical member extends at least about as far as both of said planes which bound the uniform cross-section portion of said package.

Claims

1. A blasting cartridge comprising a. a tubular member made of pliable film material, said tubular member being gathered and mechanically closed at both ends and containing a water-bearing explosive in an amount sufficient to produce a tubular package having a substantially uniform circular cross-section portion and tapered end portions continuous therewith; and b. at least one water-resistant hollow cylindrical member circumferentially disposed around, and stationarily engaged with, said package at the uniform cross-section portion thereof and extending at least about as far as the two planes which bound said uniform cross-section portion and are substantially normal to the longitudinal axis of said tubular member, said cylindrical member(s) forming two circularly bounded end abutment surfaces on said package, said abutment surfaces having an effective diameter at least about equal to that of the uniform cross-section portion of said package, and the stiffness of said cylindrical member(s) and the position and attitude of said abutment surfaces relative to said tapered portion(s) of said package being such that when said cartridge is positioned coaxially with one of its end abutment surfaces in contact with an end abutment surface of another like cartridge, a compressive force applied axially to the pair of contacting cartridges causes each caRtridge to lodge against the other''s end abutment surface, thereby impeding substantial relative motion of the cartridges.

12. A blasting cartridge comprising a. a tubular member made of pliable film material, said member being gathered and mechanically closed at both ends and containing a water-bearing explosive in an amount sufficient to produce a tubular package having a substantially uniform circular cross-section portion and tapered end portions continuous therewith; and b. a water-resistant hollow cylindrical member circumferentially disposed around, and stationarily engaged with, said package at the uniform cross-section portion thereof and extending at least about as far as both of the planes which bound said uniform cross-section portion and are substantially normal to the longitudinal axis of said tubular member, said cylindrical member forming two circularly bounded end abutment surfaces on said package, said abutment surfaces having an effective diameter at least about equal to that of the uniform cross-section portion of said package, and the stiffness of said cylindrical member and the position and attitude of said abutment surfaces relative to said tapered portions of said package being such that when said cartridge is positioned coaxially with one of its end abutment surfaces in contact with an end abutment surface of another like cartridge, a compressive force applied axially to the pair of contacting cartridges causes each cartridge to lodge against the other''s end abutment surface, thereby impeding the relative motion of the cartridges.

17. A blasting cartridge of claim 15 wherein the collapsed portions of said cylindrical member are peripheral endfolds.

18. An explosive primer comprising a. a tubular member made of pliable film material, said tubular member being gathered and mechanically closed at both ends and containing a water-bearing explosive in an amount sufficient to produce a tubular package Having a substantially uniform circular cross-section portion and tapered end portions continuous therewith; b. at least one water-resistant hollow cylindrical member circumferentially disposed around, and stationarily engaged with, said package at the uniform cross-section portion thereof and extending at least about as far as the two planes which bound said uniform crosssection portion and are substantially normal to the longitudinal axis of said tubular member, said cylindrical member(s) forming two circularly bounded end abutment surfaces on said package, said abutment surfaces having an effective diameter at least about equal to that of the uniform cross-section portion of said package, and the stiffness of said cylindrical member(s) and the position and attitude of said abutment surfaces relative to said tapered portions of said package being such that when said cartridge is positioned coaxially with one of its end abutment surfaces in contact with an end abutment surface of another like cartridge, a compressive force applied axially to the pair of contacting cartridges causes each cartridge to lodge against the other''s end abutment surface, thereby impeding the relative motion of the cartridges; and c. a blasting cap embedded within the water-bearing explosive in said package and disposed within a perforation in the film material located in the portion of said package around which said cylindrical member(s) are circumferentially disposed or in the tapered end portions of said package to which said cylindrical member(s) extend.