US2918003A

US2918003A - Deep water cartridge

Info

Publication number: US2918003A
Application number: US655803A
Authority: US
Inventors: Temple Robert
Original assignee: Mine Safety Appliances Co
Current assignee: MSA Safety Inc
Priority date: 1957-04-29
Filing date: 1957-04-29
Publication date: 1959-12-22
Anticipated expiration: 1976-12-22

Description

Dec. 22, 1959 I R. TEMPLE 2,918,003

DEEP WATER CARTRIDGE Original Filed April 19. 1950 INVEN TOR.

Robert Temple, Swissv'ale, Pa., assignor, by 'mesne assignments, to Mine Safety Appliances Eompany, Pittsburgh, Pa., a corporation of Pennsylvania Continuation of application Serial No. 156,815, April 19, 1950. This application April 29, 1957, Serial No. 655,803 I 3 Claims. c1. 192-413 This invention relates to explosive blank cartridges especially suitable for use for long periods of time in deep water where the hydrostatic pressure is very great, and more particularly to the sealing of such cartridges to prevent water from leaking into them,

The invention disclosed herein is acontinuation of copending application Serial No. 156,815, now abandoned, filed April 19, 1950 for Deep Water vCartridge and Method of Sealing It. a

Most tools now used for cutting the anchoring cables or chains of floating mines are actuated by explosive blank cartridges. When such mine cutters areused at considerable depths in the ocean and other bodies of water, such as from 500 to 1000 or more feet, they are not always dependable because the vhydrostatic pressure is so great that water may be forced into the cartridges. The cartridges may not always leak immediately but such cartridges are often submerged for hours and even days. Therefore, they should be water tight permanently. Crimping of the cartridge case over the closure in its open end is not sufficient to prevent leakage, and neither is the use of plastic sealing material between the closure and the encircling wall of the case.

It 'is among the objects of this invention ,to provide a deep water cartridge which is sealed against great hydrostatic pressure indefinitely, in which. .the seal itself is metal securely united to the adjoining metal parts, and in which great pressure is built up before the cartridge is ruptured.

In accordance with this invention, the tubular metal case of the cartridge has an-i-ntegral closed end, and an open end in which a metal closure member is inserted. The closure is soldered -to the case by a solder whose melting point is low'enough to prevent the soldering heat from igniting the powder in the case, Preferably, the cartridge case has an annular shoulder formed inside of it close to its open end. 'A metal closure is seated on this shoulder and is pressed against it by a short portion of the case projecting beyond the closure and bent inward against the latter. This crimped end of the cartridge then is dipped in molten solder which is at a temperature between about 225 and 350 F. This temperature will not heat the cartridge sufficiently to explode the double base powder, with which these cartridges generaly are filled. The soft or low melting point solder unites with the closure and the surrounding case and forms a permanent seal between them. The pressure seal prevents water from leaking into the cartridge. If desired, a separate primer head may be formed and used as the closure for the open end of the case, the opposite end of which has a thin end wall closing it and which is ruptured when sufficient pressure builds up in the case. The primer head and case are soldered together.

The invention is illustrated in the accompanying drawings, in-Which Fig. l is a longitudinal section through a cartridge just before the open end of the case has been crimped over the closure; Fig. 2 is a side view of the cartridge, partly in section, after the solder seal has been its States Pater 2 formed; Fig. 3 is a cross section taken on the line III:I1I of Fig. 2; and Fig. 4 is a longitudinal section through a modified embodiment of the invention.

Referring to Figs. 1 to 3 of the drawings, themain part of the cartridge is the usual tubular metal case which is closed at one end by an integral end wall 1 and a separate priming cap 2. The endwall forms a primer head,

and the cap is disposed in a socket in the head and is forced tightly against a seat therein by ring stakingthe outer end of the socket against the cap. This holds the 7 4, preferably the well-known double basepowder, and

then its open end is closed by a metal closure member, This member is in the form of a disc 6 of a size thatwill fit snugly within the thin walled end of he case. In tegral with the inner face of the disc is an annular flange 7 which engages the case shoulder 3. The closure is held firmly against the shoulder while the projecting end 8 of the case is crimped over the edge ofthe disc, This crimping or bending can be done in any well-known man ner while theside wall of the case js preventcdfrom bulging away from closure flange 7. Projecting end '8 extends beyond closure 6 to provide an annular wall to which solder is applied,

The crimped end of the case then is dipped ina suitable the molten solder the excess solder is wiped from the outer surface of the case. The end of the cartridge is completely tinned. 'Thesolder 9' covering and unitedto the closure and the encircling thin annular wall of th e case solders the two together and forms ,a metal seal between them that will prevent water, even at high pressure, from entering the case, no matter how long the cartridge is submerged. The solder that is 'used',preferably,is formed from 52 /2 percent bismuth, '32 percent lead-and 15 /2 percent tin. This is a soft or' low melting point solder, the melting point of which is low enough to prevent the soldering heat from igniting the powder in ;the cartridge. For the usual double base powder, the-"ternperature of the molten solder, into whichthe cartridge is dipped, should be between 225 and 350 F. The higher temperature is not great enough to ignite-such a=pow der in the cartridge case. 7

Since the bonding qualities of low melting point solder are relatively poor, it is necessary to provide adequate cartridge surface area to which the solder may be applied. The surface provided by the annular wall formed by extending projecting end 8 beyond closure 6 a short distance, together with the closure surface provide the necessary bonding surface area.

The disc 6 is thin enough to be ruptured by the pressure built up in the cartridge. It must rupture before sufficient pressure would be built up to blow the primer cap back out of the primer head. The thickness of the disc will depend on the amount'of work the cartridge is expected to do.

In the modification shown in Fig. 4 the case and the primer head are made as separate elements and then are soldered together. Thus, the tubular case 10 has an integral wall 11 closing one end, while the other end of the case is open. The open end of the case is encircled by an integrai flange 12 that extends radially outward a short distance. The primer head is in the form of a plug 13 which is inserted part way into the open end of the case.

Patented Dec, 22,

The projecting portion of the plug is encircled by an integral radial flange 14 that seats against the case flange. The plug fits snugly inside the case and is provided with the usual primer cap 16- After the case-hasbeen filled with powder17 and the primer head has been. inserted, the adjacent edges of the two

flanges

12 and 14 are soldered together entirely around the cartridge to hold them together and to, form a circular seal 18 that .will prevent water from seeping into the case. The edge of the primerhead flange adjacent the case may be chamfered to form an annular groove for. receiving the solder. Here again, asoft or low melting point solder is used so that the heat of the soldering operation will not ignite the powder in the case. When the cartridge. is fired, the pressure in it builds up until it is suflicient to rupture the front wall 11 of the case. The thickness of this wall depends upon the work that it is desired to do with the cartridge, but of course it must be thinenough to rupture before the primer cap is blown back outof the primer head. i

The rate of burning of powder in.a cartridge is directly proportional to the square of the pressure on the powder. Powder loosely disposed in a cartridge with no wadding or other obstruction in front of it will be shot out by the'primer with little or no burning. On the other hand, if resistance is ofiered, the rate of burning will increase in'proportion to the square of the resistance. The faster the rate of burning, the more complete it is and the higher the pressure produced. Therefore, it is highly desirablethat the powder in the cartridges shown in the drawings should be retained therein as long as possible after detonation of the primer, thereby giving the powder time to burn and build up high pressures in the cartridge which speed up the combustion and produce even greater pressure to do work at a rapid rate. The cartridges disclosed herein are admirably suited to this purpose, because in each embodiment of the invention the front end wall of the cartridge has to be ruptured by the pressure behind it before any work can be done. This insures satisfactory combustion of the powder and great efliciency from it. Such cartridges make it unnecessary to use external means, such as shear pins and the like, for temporarily. holding back the members that are driven forward by the force of the explosion so that the desired pressure can be built up behind them, because these cartridges are self-retarding as well as leak proof. V

According to the provisions of the patent statutes, I have explained the principle of my invention and have illustrated and described what I now consider to represent its best embodiment. However, I desire to have it understood ,that, within the scope ofthe appended claims, the invention may be practiced otherwise than as specifically illustrated and described.

I claim:

l. A deep water cartridge comprising a tubular metal case having a closed end and an open end, explosive powder in the case, the inside of the case at said open end being provided with an annular shoulder,.a metal closure seated on said shoulder, the case projecting beyond the closure to form an annular "wall and being crimped over said closure to press it against the, shoulder, solder of a melting point below the ignition point of said powder covering and bonded to the outer surface of the closure and inner surface of the annular wall, and said solder forming an annular pressure seal substantially filling the annular space between the closure and surrounding case which withstands hydrostatic pressures, above atmospheric to-protect the powder from moisture.

2. A deep water cartridge comprising a tubular'metal case having a closed end and an open end, explosive powder in the case, the inside of the case at said open end being provided with an annular shoulder, .a metal closure seated on said shoulder, said metalclosure consisting of a metaldisc encircled at one side by an integral flange, the case projecting beyond the closure to form anl annular wall and being crimped over said closure to press it against the shoulder, solder of a melting point below the ignition point of said powder covering and bonded to the outer surface of the closure and inner. surface of the annular wall, and said solder forming an annular pressure seal substantially filling the annular space between the closure and surrounding case which withstandshydrm static pressures above atmospheric to protect the powder fromrnoisture. p

3. A deep water cartridge comprising a tubular metal; case havinga closed end and an' open end, explosive powder in the case, the inside of the case atsaid open end being provided with an annular shoulder, a metal clos-; ure, seated on said shoulder, the case pr oj ecting beyond the closure to form an annularwall and being crimped over said closure to press it against the shoulder, solder of a melting point below the ignition point of said powder covering and bonded to the outer surfaceof the closure and inner surface of the annular wall, and said solder forming an annular pressure sealsubstantially filling the annular space between the closure and, surrounding case which withstands pressures at water depths of at least 500 feet to protect the powder from moisture. i

References Cited in the file of this patent T 1 UNITED STATES PATENTS I 195,620 Lyman, se fzs, 1877 951,023 OBrien Mar. 1, 1910 1,624,649 Des Allimes, ;Apr. 12, 1927 FOREIGN PATENTS, j r 29,648 Germany .Nov. 24, 1884 202,252.

Great Britain Aug. 16, 1923