US2877709A - Cartridge - Google Patents

Description

United States Patent i' CARTRIDGE Clifford L. Duckworth, East Alton, Ill., assignor to Olin Mathieson Chemical Corporation, East Alton, Ill., a corporation of Virginia Application April 23, 1956, Serial No. 579,939

3 Claims. (Cl. 102-39) This invention relates generally to cartridges and more particularly to an improved cartridge for use as a fluid power source in fluid pressure systems adapted to actuate moving parts of various mechanical devices.

It has been proposed before to utilize cartridges containing a gas generating smokeless powder composition for actuating mechanical devices such as in engine starters on airplanes, in systems adapted to eject pilots, missiles, gas tanks, and the like from airplanes, and in various other mechanical devices. Such cartridges are ordinarily provided with a smokeless powder fuel adapted to burn slowly and thus gradually build up a fluid pressure in the fluid pressure system. Various types of such cartridges have been proposed but none of them has been entirely suitable for all purposes because the specific burning rate required for use in one particular system may be quite different from the burning rate required in other fluid pressure systems. Consequently, it has been necessary to manufacture a large variety of cartridges and to more or less custom buildv the fuel charge for each fluid pressure system. Such a procedure is not only disadvantageous because of the large variety of cartridges required but also because of the time required to develop a fuel suitable for a particular purpose each time a new use is found for such cartridges. Furthermore, the burning rate of the propellent required in a particular situation may not be obtainable with a single type of powder using known deterrents and other modifiers of the burning rate of nitrocellulose and other smokeless powder bases.

It is, therefore, an object of this invention to provide a cartridge devoid of the foregoing disadvantages. Another object of the invention is to provide a cartridge that can be easily modified to be used in a number of different fluid pressure systems. Another object of the invention is to provide a gas generating cartridge for uid pressure systems that is easily ignited and consistently burns at a uniform predetermined rate. Still another object of the invention is to provide a fuel charge for cartridges adapted to be used in fluid pressure systems having improved ignition characteristics and improved burning rate characteristics. A further object of the invention is to provide a method for making an improved fuel for cartridges.

Other objects will become apparent upon reading the following description taken in connection with the aclcompanying drawing in which:

and connected to a source of resinous material.

In accordance with this invention, generally speaking,

the, foregoing objects areaccomplished by providing a" Y2,877,709 Patented Mar. 17, 1959 cartridge containing a fuel having a resinous matrix surrounding perforated rods of smokeless powder base propellant. The thickness of the sidewalls of the cartridge case adjacent the head thereof is greater than the thickness of the sidewalls of the remainder of the cartridge case. This thickened portion of the cartridge case provides a well adjacent the head of the cartridge and communicating with a primer inserted in a pocket in the cartridge case head. The well has an open end spaced from the head of the cartridge and the thickened portion of the cartridge case wall terminates in a shoulder or ledge around the inner wall of the cartridge case. An annular ring of asuitable kindling composition is placed in the well and may rest on a spacer ring adapted to position it where it will be most easily ignited by the primer. A main fuel charge consisting of a single grain of such size and configuration that it fits snugly in the cartridge case and rests on the ledge provided by the thickened portion of the cartridge case sidewall has a resinous matrix surrounding longitudinally perforated rods of smokeless powder basepropellant. The sidewalls of the cartridge case at the open end are turned over with the end of the cartridge case wall resting against a washer which urges the fuel charge against the ledge and thus confines the fuel charge in the cartridge case.

The cartridge case may be molded from any suitable resinous material, for example ethyl cellulose, polyethylene, polystyrene, cellulose acetate or the like, or it may be formed from any suitable metal, for example brass, steel, aluminum or the like.

The spacer ring in the well of the cartridge case may be a molded resinous ring, for example, formed from ce1- lulose acetate,'ethyl cellulose, or it may be formed from rubber, synthetic rubber, or a suitable metal such as brass, copper, steel or the like.

The primer may be a conventional ammunition type primer either impact sensitive or one that is initiated electrically. An. example of suitable compositions include those containing from about 30 to about 45 partsv normal lead styphnate, basic lead styphnate, or the like, about 30 parts to about 40 parts of an inorganic oxidizing salt such as, for example, potassium nitrate, sodium nitrate, potassium bichromate, barium nitrate, lead peroxide and the like and about l5 parts to about 30 parts of a suitable fuel such as powdered aluminum, zirconium and the like.

The kindling composition may be black powder contained in a suitable washer shaped plastic bag such as a polyethylene bag or a bag made from regenerated cellulose, or the like, or it may be a molded ring of black powder, tetryl, or other explosive suitable for use as a booster and ignitable by the priming composition.

The fuel charge is a single grain and has longitudinally perforated rods of .smokeless powder base extending through the length of the grain. These rods of smoke- .less powder base are surrounded by a matrix of a thermosetting resin which supports the rods in the cartridge case and aligns them with the primer and kindling composition to insure proper ignition. Because of the alignlment of the perforated rods in substantially parallel renot contribute appreciably tothe generation of gas. In

fact, with `sorne resinous matrixes of high melting point and low combustibility, very little burning or charring results.

The rods of propellant may be shaped from any suitable smokeless powder base. They may `consist of nitrocellulose or may be formed from mixtures of nitrocellulose with a liquid explosive polyhydric alcohol such as, for example, nitroglycerine, nitroglycol and the like or the grains may be shaped from propellent compositions having a nitrocellulose base and containing particles of a solid inorganic oxidizing salt. Examples of such inorganic salts are barium nitrate, potassium nitrate, potassium sulfate, ammonium nitrate, ammonium perchlorate, sodium perchlorate, potassium chlorate, lead peroxide, tin dioxide, lead stearate and the like, and mixtures thereof. The propellant may also contain particles of a metal that will modify the burning rate of propellant. Examples of such metals include powdered tin, aluminum, lead and the like.

If maximum progressive burning characteristics are desired, the rods of propellant should extend entirely through the grain and should have a longitudinal perforation extending therethrough. If the rods are easily ignitable and it is desired to have a maximum progressive burning grain, the end of rods adjacent the kindling composition may be coated with the resinous material of the matrix, but the perforations in the rod should not be closed with resin. The molded grain may have a suitable resinous matrix and contain a plurality of rods of propellant of the same composition or each having a different composition from that of the other. By having available rods of various compositions, a propellent grain having practically any desired burning rate may be made by properly selecting the combination of different rod compositions required.

In order better to describe and further clarify the invention, the following is a detailed description of one embodiment thereof.

One embodiment of the invention is illustrated in Figure l having an aluminum cartridge case 1, having closed end shaped into a conventional cartridge case head 9 with primer pocket 11 containing primer 12. The head portion of the cartridge and the sidewalls adjacent thereto are thicker than the sidewalls of the remainder of the cartridge forming a well 13 and a ledge or shoulder 14. A spacer ring 8 lies against head 9 and supports an annular ring of black powder 7 inclosed in regenerated cellulose, Fuel 4 is a molded grain that tits snugly in the cartridge and occupies substantially all of the space between shoulder 14 and a washer 2 adjacent the open end of the cartridge case. The sidewalls of cartridge case 1 are turned over to form a roll type crimp 3 with the end of the cartridge case wall urging wad 2 against the exposed surface of grain 4 which, in turn, presses grain 4 against ledge 14. As shown in Figure 2, grain 4 is composed of a resinous matrix 1S and 3 rods of smokeless powder base propellant 5 longitudinally disposed in the matrix and having a single longitudinally extending perforation 6. ln this particular embodiment, each of the rods 5 has the composition of about 50 parts by weight gelatinized nitrocellulose having a nitrogen content of about 13.25 percent, about 4S parts nitroglycerine, about 3 parts diethylphthalate, about l part ethyl centralite, about 1 part potassium sulfate, about 0.1 part candelilla wax and about 0.1 part powdered carbon black.

In another embodiment of the invention, the cartridge has the same component parts as the one described in the foregoing in detail except that in this embodiment, one of the rods 5 has the same composition as that described above while the other two rods are of dilerent composition. For example, one of the rods may have a composition of about 97 percent gelatinized nitrocellulose having a nitrogen content of about 13.15 percent, about l percent stabilizer such as ethyl centralite or diphenylamine and about 2 percent of a deterrent such as dibutylphthalate or other suitable deterrents including ethyl centralite or other dialkylphthalates like diamylphthalate or a diarylphthalate such as diphenylphthalate 0r the like. The third rod may be a double base smokeless powder containing about percent gelatinized nitrocellulose having a nitrogen content of about 13.15 percent, about 10 percent nitroglycerine and about 5 percent of a suitable dialkylphthalate deterrent. ln other embodiments, only one or two rods 5 may be utilized or the grain may contain several rods of up to say 5 or 6 rods of similar or different compositions.

The apparatus shown in Figures 3 and 4 has been found particularly advantageous for molding a propellent grain for the cartridge of this invention. The rods of propellant 5 are placed on wires or metal rods 16 and the ends of the wires 16 are placed in one of the perforations 17 in each of end plates 18 and 19. After the required number of rods 5 have been disposed substantially parallel to each other between end plates 18 and 19 sidewalls 20 and `21 are placed about the rods and rest on the shoulder of the perforated plates 22 on end plates 18 and 19. Bottom plate 23 is also positioned between end plates 18 and 19 and the entire assembly is fastened together by means of screws or other suitable means. The resulting air-tight mold assembly is then placed on end plate 19 and the mold is connected through port 24 to a `suitable source of molten resinous material such as tank 25 illustrated in Figure 4. The resinous material is then forced through tube 26 into the mold until the interstices between the rods 5 are entirely lled with resinous material. Port 27 provides an exit for the air in the mold. Resinous material is added to the mold until it begins to emerge therefrom through port 27. The contents of the mold are then placed in a heated atmosphere until the resin has set. For most thermosetting resins such as a polyester, a period of about 12 hours at from 40 to 50 C. is required to properly cure the resin. Obviously, the temperature to which the mold is heated must not exceed the ignition temperature of rods 5. After the curing period, the contents of the mold are cooled to room temperature and the resulting grain is removed from the mold. If the grain has been molded to the proper length, it is ready to be inserted into the cartridge case. lf the length of the grain is some multiple of the length required for the cartridge, it is iirst cut into the proper lengths and then inserted into the cartridge.

Although the invention has been described in considerable detail in the foregoing for the purpose of describing the invention, it is to be understood that such detail is solely for that purpose and that many modifications can be made by those skilled in the art in the cartridge and in the process for making it without departing from the spirit and scope of the invention except as it may be limited by the appended claims.

1 claim:

1. A cartridge comprising a case with a head portion and a cylindrical body portion, a primer in the head portion, the cylindrical body portion having two internal diameters, the lesser diameter being adjacent the head portion, thereby forming a well terminating in a ledge joining the two diameters, a booster charge in said well, a propellent grain comprising a resinous matrix and longitudinally perforated rods of smokeless powder base propellant, said propellent grain resting against said ledge and fitting snugly within the case, a void between said booster charge and said propellent grain, and an end closure on said cartridge comprising a washer lying on said propellent grain, the open end of said case being turned over and pressed against said washer, thus confining said propellent grain in the cartridge and against the cartridge case head.

2. A cartridge having a metallic case comprising a cylindrical body open at one end and closed by a head at the other end, the portion of the body adjacent the head having a reduced internal diameter thereby form ing a well adjacent said head of less diameter than the remainder of the body, the well terminating in a ledge around the open end of the well, a primer in the head, a booster charge in the well, a propellent grain comprising a resinous matrix and longitudinally perforated rods of smokeless powder base propellant extending longitudinally through the grain, said propellent grain being directly ignitable by said booster charge, a washer lying on the grain, the open end of the cartridge being turned over and against said washer and confining said grain in the cartridge case.

3. A cartridge having a case comprising a cylindrical body open at one end and closed at the other end by a head, said head having a pocket containing a primer, the internal diameter of the body being stepped down adjacent the head thereby forming a well adjacent the primer having an open end remote from the primer terminating and forming a ledge at the open end of the well, an annular ring of explosive ignitable by said primer in the well, a propellent grain having one end resting against said ledge and tting snugly in said case comprising a resinous matrix and a plurality of longitudinally perforated rods of smokeless powder base propellant extending longitudinally through the grain, said propellent grain being directly ignitable by said annular ring of explosives, and end closure at the open end of the cylindrical body comprising a resinous washer lying on the grain, at the open end of the body being turned over to form a crimp thereby urging the powder grain toward the ledge and confining said grain within the cartridge.

References Cited in the ile of this patent UNITED STATES PATENTS 321,374 vLyman June 30, 1885 1,920,075 Haenichen July 25, 1933 2,090,608 Holm Aug. 17, 1937 2,549,005 Preckel Apr. 17, 1951 2,568,274 Clark Sept. 18, 1951 2,816,418 Loedding Dec. 17, 1957 FOREIGN PATENTS 21,296 Great Britain of 1898 159,248 Australia Oct. 8A, 1954

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