US2129388A

US2129388A - Blasting explosive device

Info

Publication number: US2129388A
Application number: US15643A
Authority: US
Inventors: Taylor James; Young William
Original assignee: Imperial Chemical Industries Ltd
Current assignee: Imperial Chemical Industries Ltd
Priority date: 1934-04-20
Filing date: 1935-04-10
Publication date: 1938-09-06
Anticipated expiration: 1955-09-06
Also published as: GB436860A

Description

Sept. 6', 1938. J. TAYLOR ET AL BLASTING EXPLDSIVE DEVICE Filed April 10, 1935 James Ta [or INVENTORS ATTORNEY.

Sept. 6, 1938. J. TAYLOR El AL 2,129,388

BLASTING EXPLOS IVE DEVICE Filed April 10, 1955 2 Sheets-Sheet 2 James T615202 INVENTORS W'i/Zz'am yaunj BY W ATTORNEY.

Patented Sept. 6, 193a UNITED PATENT OFFlC BLASTING EXPLOSIVE DEVICE Application April 10, 1935, Serial No. 15,643 In Great Britain April 20, 1934 14 Claims. 102-6) This invention relates to devices for use in blasting, the said devices being of the kind in which a charge of gas-producing materials, together with a suitable initiating device, is enclosed in a rigid container provided with a closure member adapted to release the gases from the container at a predetermined pressure so that a blasting effect -is produced in the borehole, the

body of the container being sufiiciently strong to .0 withstand theexplosion and being capable of reutilization. The gas-producing charge may comprise a slow burning explosive, such as blackpowder, or any other suitable gas forming material such as for example, a highly compressed or 5 liquefied gas. 'The charge may also comprise a chemical mixture capable of undergoingan exo- 1 thermic reaction'with generation of gas when suitably initiated, although not adapted to react under normal conditions with explosive violence.

:0 gIn blasting devices of the kind described the gas release member usually takes the form of a. rupturablesteel disc sealing a vent from the container and held in place by a hollow cap screwed to the container. It has also been proposed to i; employ a suitably adjusted valve or othermechanical form of release device similarly situated within a hollow cap. ,Discharge caps ofthis nature are provided with, channels or ports I through which the gases escape and these chan- 0 nels or parts have hitherto consisted of a single row of radial apertures formed at right angles to the longitudinal axis of the cap and having a total ventingarea usually approximately equal to the cross sectional area of the container.

5 According to the present invention a blasting device of the kind described comprises a contain- I er of substantially uniform cross section throughout at least the greater part of its length, and an elongated cap provided with a plurality of rows 0 of venting apertures of about the customary size distributed uniformly over the cylindrical surface of the cap, the total-cross sectional area of the venting apertures being considerably greater than the internal cross sectional area of the container.

5 Itis preferred thatthe total area of the venting apertures should be at least twice the internal ably not exceeding four times this area although beneficial'results may be obtained when the ratio 0 is as great as five to one or even higher.

The venting apertures are preferably located so that their centres lie in a plurality of planes spaced substantially uniformly along the lon'gitudinal axis of the cap and perpendicular there- 5 to. It is preferred that there should be at least cross sectional area of the container but prefer=:.

three series of apertures lying in separate planes but preferably not more than five.

Discharge caps constructed in accordance with the present invention permit of very eiiicient venting of the gases generated in the container over a relatively large area of the borehole. The rapid and eflicient venting of the gases minimizes any risk of bursting or cracking of the head.

It .will be understood that the caps of the presl0 ent invention are relatively long (for agj-given diameter) as compared with the caps hitherto employed in the art. It will also be understood that the amount of material removed from the cap to form the venting apertures must not be so great as 'to weaken the cap mechanically and the invention provides a method whereby the ratio of the venting area to the internal cross sectional area may be increased considerably without the necessity of increasing the diameter of the cap and hence the diameter of the borehole.

According to a further feature of the invention the venting apertures are located at an acute angle to the longitudinal axis of the discharge cap and in a backward direction in the manner described and claimed for a single row of apertures in pending application No. 752,924.

In order to improve still further the eil'icient venting of the gases the length of the blasting cap occupied by the venting apertures may be formed with a slightly reduced external diameter as compared with the external diameter of the modifying the shape of one of the forward apertures. It is necessary, however, simultaneously to modify one of the venting apertures at the remote side of the cap so that the total venting area is stilluniform about the longitudinal axis.

Various forms of the invention will now be described with reference to the accompanying drawings in which Figure l is a longitudinal section showing a cap in position in a container and so constructed in accordance with the invention. Figures 2, 3, 4 and 5 show in longitudinal section alternative forms of cap which may be used with the same container indicated in Figure 1.

Referring to Figure 1, the cap I constructed of posed between the' container and the cap.

1 disc.

metal is attached to the Container 2 by means of a screw thread 3, a bursting disc 6 being inge external diameter of the cap is the same as that of the container. The internal diameter 5 of the container in uniform throughout substantially.

the whole length thereof; but is restricted at the end to form a throat 6 adjacent to the bursting The cap is provided with an axial passage 7 and this passage communicates with theexterior by means of three groups of ports 9, l0 and H Each group consists of four ports equally spaced around the discharge cap and lying in a.

plane at right angles to the. longitudinal axis 'of of each of the ports in-any. row isf at anangle oi? 45 with the direction .of ports in each "adjacent may be obtained by employing a bursting disc adapted to rupture at about 13 tons per square inch and a cap constructed in the manner illustrated having an internal diameter of A and provided with ports of diameter. In the form illustrated in which there are 12 ports in all the ratio of the venting area to the internal cross sectional area of the container is approximately 2 :1.

By comparison with this cap constructed in accordance with the present invention a typical cap hitherto employed in the art as suitable for the same container is provided with one row only of 4 venting apertures of diameter, the total venting area being equal to the internal cross sectional area of the container.

Referring to Figure 2, the cap illustrated is designed for use with the same container as indicated in Figure 1, and the reference numerals employed have the same significance as in the description of Figure l, but in this cap there are provided five rows of. ports, three rows 9, i I and I3 being in line with each other, and two intermediate rows l0 and it being staggered with respect thereto at a radial inclination of 45. All the ports are pierced at an angle of about 60 with the longitudinal axis of the cap. The exterior of the cap is recessed as indicated at the upper end it and the lower end so that the cap is reduced in diameter over that part of its length which is occupied by the ports. The'cap' may be constructed of similar dimensions to that described in Figure 1, it being understood that the length is suitably increased to accommodate the" two additional rows of ports. The cap may conveniently be 6%? long excluding the screwthreaded end, the ports being distributed over a length of 4%". The ratio of the total venting area 'to the cross sectional area of the container is 3.6 :1.

Referring to Figure 3, the cap is provided with only three rows of ports but in place of one of the ports of the most forward row a deep slot I6 is cut longitudinally in order to permit the escape of the ruptured sealing disc, and this aperture is balanced by a second slot ll cut greases peripherally on the other side of the cap. The

axial aperture indicated at the head of the cap as in Figures 1 and 2 is omitted In the jeep I illustrated in Figure 4 provision for the escape 5 of identical with the can illustrated n Figure-2 with} the exception that thepbrtsa e at right angles to the longitu ineifaxisfi'rh dimensions-oi the 'cap and the ratiooflthe vesting. area to tn'emternal cross sectional area-of *the'" container are. p jithe same as in the'cap. illustratedin'li'igure. 2. the container and cap; Theintermediate group of ports i0 is staggered-with respect 'toi the other two groups 9 and II so thattheradial'direction section throughout at least the greater part of its '1. A blasting olevi oe -bf-.' tlie 1kinddescribed eom prising a container ofsubstantially uniform, cross length, and anelongatedcap provided with a plurality of rows of venting apertures distributed uniformly over the cylindrical surface of the cap; the total cross sectionalarea of the venting apertures being at least 3% times as large as the internal cross sectional area of the throat of said container.

2. A blasting device of the type wherein a charge of' gas-producing material isenclosed in a pressure-resistant container provided with a member adapted to permit the escape'of gasesat a predetermined and considerable pressure, lsaid blasting device comprising .a container'jof substantially uniform cross section throughout at least the greater part of its length, but provided with a restricted throat, and an elongated cap provided with at least three but not more than five rows of venting apertures distributed .uni'-. formly over the cylindrical surface of the cap, the total cros ssectional area of the venting apertures being at least 3% but not more than 6% times the internal cross-sectional area of th throat of said container.

3. The blasting device of claim 2, inwhich the venting apertures in each row are staggered with respect to the venting TOW. j

4. A blasting device of the "type wherein a charge of gas-producing material is enclosed in a pressure-resistant container provided with a member adapted to permit the escape of gases at a predetemined and considerable pressure, said blasting device comprising a container of substantially uniform cross section throughout at "least the greater part of its length, but provided with a restricted throat, and an elongated cap provided with at least three but not more than five rows of venting apertures, the centers of apertures in each adjacent which lie in a plurality of planes spaced sub stantially uniformly along the longitudinal axis of the cap and substantially, perpendicular thereto, the total cross-sectional area of the venting apertures being at least 3% but not more than 6% times the internal cross-sectional area of the 7. The blasting device of claim 4, in which that portion of the discharge capwhich is provided with venting apertures has anexternal diameter slightly smaller than that of the container.

8. A blasting device of the type wherein a charge of gas-producing material is enclosed in a pressure-resistant container provided with a member adapted to permit the escape of gases at a predetermined and considerable pressure, said blasting device comprising a container of substantially uniform cross section throughout at least the greater part of its length, but provided with a restricted throat, and an elongated discharge cap provided with at least three but not more than five rows of venting apertures, the centers of which lie in a plurality of planes spaced substantially uniformly along the longitudinal axis of the cap and perpendicular thereto, the venting apertures in each row being staggered with respect to the venting apertures in each adjacent row, the axes of said venting apertures forming forwardly-pointing acute angles with the longitudinal axis of said cap; and the total cross sectional area of the venting apertures being at least 3%; but not more than 6% times the internal cross-sectional area of the throat of said container.

9. The blasting device of claim 8, in which one of the forward apertures of the cap is modified to permit the expulsion of the sealing disc after rupture, a corresponding modification being made in an aperture on the other side of the cap.

10. The blasting device of claim 8, in which that portion of the discharge cap having venting apertures exhibits an external diameter slightly smaller than that of the container.

11. A blasting device of the type wherein a charge of gas-producing material is enclosed in a pressure-resistant container provided with a member adapted to permit the escape of gases at a-predetermined and considerable pressure, said blasting device comprising a container of substantially uniform cross section throughout at least the greater part of its length but provided with a restricted throat and an elongated cap provided with at least three but not more than five rows of venting apertures distributed uniformly over the cylindrical surface of the cap, the total cross-sectional area of the venting apertures being at least twice but not more than four times the internal cross-sectional area of the container, and at least 3% but not more than 6% times the internal cross-sectional area of the throat of said container.

12. A blasting device of the t3, wherein a charge of gas-producing material is enclosed in a pressure-resistant container provided with a member adapted to permit the escape of gases at a predetermined and considerable pressure, said blasting device comprising a container having internal and external diameters of approximately 1%" and 1%" respectively, and a constricted throat of approximately diameter at the venting end, and an elongated cap provided with twelve ports of approximately /2" diameter 13. A blasting device of the type wherein a charge of gas-producing material is enclosed in a pressure-resistant container provided with a member adapted to permit the escape of gases at a predetermined and considerable pressure, said blasting device comprising a container having internal and external diameters of approximately 1 and 1%" respectively, and a constricted throat of approximately diameter at the venting end, and an elongated cap provided with fifteen ports of approximately /2 diameter.

14. A blasting device of the type wherein a charge of gas-producing material is enclosed in a pressure-resistant container provided with a member adapted topermit the escape of gases at a predetermined and considerable pressure, said blasting'device comprising a container of substantially uniform cross section throughout at least the greater part of its length, and an elo'ngated discharge cap provided with at least three but not more than five rows of venting apertures, the centers of which lie in a plurality of planes spaced substantially uniformly along the longitudinal axis of the cap and perpendicular thereto, the venting apertures in each row being staggered with respect to the venting apertures in each adjacent row, the axes of said venting apertures forming forwardly-pointing acute angles with the longitudinal axis of said cap; one of the forward apertures of said cap being modified to permit the expulsion of the sealing disc after rupture, a corresponding modification being made in an aperture on the other side of said cap, and the total cross-sectional area of the venting apertures being at least twice but not more than four times the internal cross-sectional area of the container.

JAMES TAYLOR. WILLIAM YOUNG.