US2312744A - Blasting cartridge shell - Google Patents

Description

March 2, 1943. c BARKER BLASTING CARTRIDGE SHELL Filed Nov. 22, 1939 INVENTOR v C'ZAUDE L. 645mm Patented Mar. 2, 1943 1 2,3123% BLAST-ING CARTREGE SH Claude L. Barker, Denver, 0010., 'assignor to E. I.

du Pont de Nemours & Company, Wilmington, Del., a corporation Delaware Application November 22, 1939, Serial No. 305,631

1 Claim.

This invention relates to an improved explosive cartridge for use in blasting operations, and more particularly to a modification im the form of the wrapper about said cartridge whereby increased effectiveness is realized- Dynamite cartridges commonly comprise pre- (Cl. roe-24) formed cylindrical paper shells which have been the packages arerelatively rigidin nature and,

deformable only with difiiculty. Various diam- The object of my invention is an improved explosive package that overcomes the dificulties heretofore encountered. A further object is an explosive cartridge which is readily conformable to the shape and size of the borehole by means of ordinary tamping procedures. A further object is such a cartridge which becomes readily wedged into a borehole and fills it completely is an explosive cartridge contained in a wrap-' eters are used for such cartridges, 2. common size being 1 inches in diameter by 8 inches in length.

In blasting it is customary to drill a borehole into the rock, the diameter of the hole depending on the diameter of the dynamite cartridge to be inserted. The cartridges are loaded to the desired depth in the hole, each one ordinarily being tamped or rammed tightly into position with a long rod. It frequently happens that the boreholes contain irregular portjons which are larger in diameter than the cartridges to be inserted. It would be desirable to rupture the dynamite wrapper and allow the explosive to fill the hole completely under the effect of vigorous tamping, thus enhancing the blasting execution. The rigidity of the filled cartridge, however, makes such rupture very difilcult, even impossible, in many cases. Trouble from the same cause is likewise met in loading pulverulent high explogravity. Difliculties of the above nature have without the necessity of any preliminary treatment at the place of use. A still further object per of such construction as to bring about the advantages cited. Additional objects will be described .as the invention is disclosed further hereinafter.

I have found that the foregoing objects are attained and the obstacles of prior practice overi come by enclosing the explosive in a shell of rupturable material having rows of perforationsor other weakening indentations in rectilinear arrangement. It is essential that the row of perforations be disposed in a spiral around the sides of the finished shell so that the row makes an acute angle with the axis of said shell. In one embodiment, the perforations in'the paper are so placed that in the rolled cartridges the rows of perforations are superposed on one another. In another embodiment, the rows are offset in the rolled cartridge. Such an explosive package presents a rigid appearance and does not become distorted in handling. When charged into av I borehole, however,brealring of the paper wrapbeen met by the procedure of slitting the cartridges with a knife so that the explosive material can readily expand and conform to the size and shape of the borehole. The slittingoperaallel sides.

per along the lines of the rows of perforations presents no difflculties and the explosive takes the form of the borehole and fills it completely.

In order'that the shape of the shell paper and the arrangement of the perforations may be seen more clearly, Figure 1 shows a sheet of paper of trapezoidal form adapted to serve as the wrapper for explosive cartridges. Figure 2 shows a similar paper sheet in the form of a parallelogram. Figure 3 is a view of a completed cylindrical explosive package accordingto the present inventionT Referring to Figure l, the size of the sheet ABCD' will depend on the diameter of the cartridge intended. Assuming a 1%" x 8"- cartridge, suitable dimensions will comprise lengths 017%" and 11% for the parallel sides and 10" for the perpendicular distance between said parsisting of small circular openings resembling pin holes are made in the shell paper alongthe straight lines GI, FJ, and KL, these rows stop: Pmsabtmt 1" from the edge of the paper sheet Parallel-rows of perforations conalong the parallel sides but extending to the very edge wherever they meet the non-parallel sides. The slope of the rows of perforations is such as to form approximately a 50 angle with the base and top of the sheet. The explosive container is prepared by forming the paper ABCD into a cylinder about a rotating mandrel, with the end of the mandrel extending to the line GH. The protruding portion is then bent inwardly at a plurality of places and so pressed that a stiff crimp is formed. It is not necessary to the invention that the rows of perforations be superposed on one another in the rolled cartridge. However, this arrangement may be employed, if desired. If such a structure is cOntemplated the rows are separated along the lines EF and GH by a distance substantially equivalent to the circumference of the cartridge, that is by about 3.9" in a cartridge of 1%." diameter. In the embodiment in which no exposed perforations appear on the wrapped cartridge, it is im-.

portant that I be removed from E by a distance at least as great as the circumference. The above cylindrical container is filled with explosive material to the level EF, and the cartridge is closed tightly by crimping over the portion Figure 2 is similar to Figure 1 except that it shows a paper sheet of the shape of a parallelogram, namely, MNOP. Intended for a 1 x 8" cartridge. again, suitable dimensions will be a height of a length of top and bottom sides of 9", and a base angle of around 70. Rows of perforations are made in the shell paper, the rows again starting at points about. 1" from the top and bottom parallel sides of the sheet but v extending to the edge of the sheet onthe sides MP and 0N. These rows, sU, VW, and Y are parallel to one another and are separated by a distance equal to the circumference of the wrapped cartridge, approximately 3.9" for a 1%," diameter cartridge. are sloped so that the acute angle with the top and bottom parallel sides is approximately 50.

' vIf it is intended that no perforations are-to be exposed on the wrapped package, the top of the first row of perforations is separated from the edge of the sheet by a distance QU, at least as great as the-circumference of the cylindrical cartridge. -The cylindrical container for the explosive is prepared. as in Figure 1, by rolling about a mandrel and crimping. The cartridge, filled to the level QR, is closed tightly by folding over the emergent paper. I

In" Figure 3, the completed perforations GI are depicted on the finished cylindrical explosive package orcartridge.

The. rows of perforations" I particularly to paper shells, but it will be under- In the foregoing specific embodiments of cartridges formed from papers weakened in accordance with the invention, three rows of perforations have beenshown. In many cases, two rows may be sufilcient and ,the outer rows GI and SU of Figures 1 and 2,-re'spectively, may be omitted.

In all events, however, I prefer to have more than one row of such perforations in the shell paper blank. -While I have applied the embodiments to shell papers for.1 diameter car- T tridges, it will be apparent that the invention is applicable to all diameters, 1 2'! etc., and even unto the vary large diameters. The illustrations have shown the perforations stopping at a distance from the top and bottom sides of the paper substantially equal to the amount crimped over. In a cartridge of 1%" diameter,

this distance may be approximately 1", while vention is applicable to cartridges containing all types of explosive whether pulverulent, gelati in the 2" cartridge diameter, it may be about 1 In general, the larger the diameter, the greater the width of paper utilized in crimping. It is undesirable from the point of view of tightness of cartridge that the perforations come completely to the edges of AB and CD.

pendicular to the longitudinal axis of the wrapped package. I have found that the acute angle of the rows of perforations with said parallel sides should be within the range of 35 to 70, and: preferably between 45 and 55, for instance about 50. That is, the row of perforations of the'flnished cartridge will make an acute angle of 20 to 55 with the axisbf said cartridge. Such an angle assures greater ease in rupturing the shell by the tamping operation and assures also that the paper will spiral open and remain generally around the column of the powder. While various types of perforations may be used, I find circular holes to be-eriective where these are of such size as to allow between 10 and 14 per inch.

The utilization of explosive cartridges in accordance with the invention makes it possible to load them into bore-holes and by comparatively mild tamping thrusts, to cause said cartridge to rupture along the lines of the perforations. With my improved cartridge, for example, I have found that one firm stroke of the temp is suflicient to secure the explosive in a smooth hole directed upwardly, while about three strokes are suflicient to give the maximum loading densityf An outstandingadvantage of the improved cartridge of my invention lies in the fact that the miner is no longer obliged to slit the car tridge before tamping the same. Thus, he avoids spilling powderand actually handling the loose powder. The time involved in the splitting operation is also saved. This becomes a big factor when a loading of 300 or more cartridges is involved. Y

.In describing the invention I have applied it stood that any type of shell other than paper may be used, provided said material is rupturable under the conditions outlined. Such materials as regenerated cellulose film and various other natural and synthetic materials are applicable,

It is apparent also that the cartridges according to my invention, may or may not be coated with paraffin or other waterproofing agent. The in nous; or semi-gelatinous dynamites. I- find it particularly advantageous in the 'case of the semi-gelatins, and with such explosives, which are more plastic in nature, two rows ofperforations may be sufijicient. The invention is not limited, however, to use with dynamite compositions but may be applied in the case of cartridges .filled with black powder or any other explosi ve material.

Inshells having a diagonal wrap, that is a wrap in whichthere is a diagonal overlap on the outside of the finished shell so that the edge of the shell paper spirals me finished shell. it is.

preferred that the row of perforations should not cross this spiral diagonal edge at the paper. but

shall spiral around the shell in the same general direction as said edge 01' the paper. at the same time making an acute angle with the axis of the completed cartridge.

shell and in procedure without departure from the spirit of the invention. I intend to be limited therefore only by the following claim.

I claim:

A substantially cylindrical explosive package 16 comprising an explosive composition encased in it rolled shell, said shell being formed from .a-

quadrilateral sheet of rupturable material having at least one set of parallel opposite sides perpendicular to the longitudinal axis of the filled cartridge. said sheet being characterized by at least one row of weakening perforations, said row being so sloped that it meets the said parallel sides of the shell material at an angle between 45 and 55, said sheet being rolled into cylindrical form so that the perforations are spirally disposed on and extend substantially from end to end of the finished shell. a

CLAUDE n BARKER.

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