US3182595A - Igniter assembly containing strands of benite - Google Patents

Description

Mayu, 1965 H. F. HAssMANN 3,182,595

IGNITER ASSEIBLY CONTAINING STRANDS 0F BENITE mea .my zo. 1962 a u v1-1 INVENTOA Herrg Haast-n ann.

black powder ingredients United States Patent Oli 3,182,595 Patented May 11, 1965 ice 3,182,595 IGNITER ASSEMBLY CNTAININ G STRANDS F BENITE Harry F. Hassmann, Sparta, NJ., assigner to the United States 0f America as represented by the Secretary of the Army Filed July 20, 1962, Ser. No. 211,461

1 Claim. (Cl. IGZ-86.5)

(Granted under Title 35, U.S. Code (1952), see. 266) The invention described herein may be manufactured and used by or for the Government for governmental purposes without the payment to me of any royalty thereon.

This invention relates to a new igniter and particularly to a new igniter material designated Benite. This material is essentially an extruded form of black powder manufactured by standard solvent propellant processing equipment. Benite is a formulation containing (sulfur, charcoal, and potassium nitrate) in a nitrocellulose matrix.

Necessity for an improved igniter was emphasized when high explosive, high velocity finned antitank projectiles Came into use. Serious problems arose from the poor ignition of triple-base powders at low temperatures. Benite igniters consisting of metal primer bodies loaded with Benite strands, exhibit better performance characteristics over similar standard igniters loaded with Grade -1 black powder, especially at low temperatures. The use of strands overcame the basic problem of resistance to the flow of combustion gases in the igniter tube which retarded the rapid and uniform ignition of granular black powder and prevented the uniform venting of the combustion gases which occurred in a packed bed of black powder. Benite strands minimize gas ow resistance and permit the igniter energy to be released from the igniter at a much faster rate than in standard black powder igniters and primers.

Benite possesses several other advantages over black powder. Benite is less hygroscopic than black powder since nitrocellulose protects the charcoal from moisture and at 90% relative humidity and 30 C., the hygroscopicity is 1.9% as compared to 2.7% for black powder. Benite also has a higher caloriic value than black powder. The heat of combustion for Benite is approximately `910 calories per gram at 1 atmosphere as compared to 700 calories per gram for black powder.

The primary object of this invention is to improve the burning performance of propellant igniters and primers.

A further object of this invention is to provide an improved ignition igniter for high velocity projectiles.

Another object of this invention is to provide a method to about 32 inches and approximately 0.08 inch in diameter, weighing 30 up to 1600 grains, are sealed in a paper foil liner 2 which covers all the holes in the body 5. These holes are sealed with a lacquer to a position of flush or slightly below flush with the outside surface. The body 5 which is one inch longer than the nominal length of the strands is closed by the head '7 and closing plug 4 which are threaded and coated with a coating compound 3. A percussion primer 6 is actuated by firing plug 9 contained in the battery cup 8. The joint seal between the percussion element 6 and the head '7 comprises -cellulose nitrate lacquer 10.

The composition of Benite is as follows:

Constituent- Percent by weight Nitrocellulose 39-41 Potassium nitrate 1 43.3-45.3 Sulfur 6.0-6.6 Charcoal 9.1-9.7 Stabilizer (added) 2 0.4-0.6

1The potassium nitrate is pulver-ized to an average diamestiof 10 to 30 microns as determined by a Fisher Sub-Sieve 5Ilil'thyl Centralite or Nitrodiphenyiamine.

The total volatiles in Benite powder should not be more than 2.25 percent by weight and the moisture content should not exceed 1.0 percent by weight. The group of strands should be suiciently straight to permit insertion, without force, into the igniter tube.

Benite powder which is extruded in the form of long cords has a diameter of approximately 0.08 inch. All standard percussion or electric elements, heads, and closing plugs are used in the igniter assembly except for the body which requires a modified flash hole pattern. The Benite igniters may be used in the same manner as standard percussion or percussion-electric artillery igniters and primers for fixed or semilixed artillery ammunition. Rocket booster charges and center cores for separate loading ammunition also may utilize the long cord Benite igniter powder.

Benite powder may be extruded and cut into cylinders Whose dried dimensions may be about 0.035 inch in diameter by 0.035 inch long or smaller. The Benite in this form can be used in base igniter pads in the same manner as Grade A-l black powder for separate loading ammunition.

The improved performance of an igniter employing Benite strands over a conventional black powder igniter was evident in the firings of a 90 mm. high explosive antitank round at A- F. This ammunition employs 8 pounds 4 ounces of triple base propellant with finned projectile. A summary of the results is given below:

of manufacturing a high performance igniter from inexpensive, readily available materials.

Other objects will become apparent to those skilled in the art from the following disclosure.

Practical embodiments of the present invention may be further illustrated by the accompanying drawing which shows a side View of the Benite primer.

Referring to the drawing, long strands of Benite 1 up Benite is manufactured with considerably less hazard than black powder. The wet mixing and solvent extrusion employed in the manufacture of Benite permits the safe utilization of existing equipment and less specialized skills than in the manufacture of black powder.

In the production of Benite, the nitrocellulose blocks are broken up in a Baker-Perkins sigma-blade mixer for 30 minutes. The 2/1 ethyl ether/ethyl alcohol mixed solvents with ethyl centralite are added so as to wet all the nitrocellulose bers, and then the `slurry is mixed for 15 minutes. The ratio of solvents to total solids is 0.6. The potassium nitrate, sulfur, and charcoal are added to the slurry-in the mixer and mixed for one hour at 50 to 60 F; or until good consistency for extrusion is= attained. The extrusion is performed with a 4 inch Logan hydraulic press or larger extrusion equipment. The doughy material is screened using No. 12 and 24 screens, blocked at 2400 p.s.i. for 5 minutes, and extruded through a 0.1102 inch die at 1150 p.s.i. The extruded strands are Wrapped on drying racks and dried for 7` days at 70 F. followed by 7 days at 105 F. The

dried Benite strands can then be cut to the desired length. Alternatively, granulated Benite powder grains are made by extruding the doughy Benite material through a 0.041 inch die or smaller at 2500 p.s.i. The extruded Benite strands are cut to a 0.04 inch length or smaller by ay McKiernan-Terry propellant cutting apparatus or equivalent, and air dried for 3 days at 70 F. and for 7 days at 105 F.

I claim:

An igniter assembly for use in high velocity ammunition comprising a tubular body having llash holes therein, a tubular liner tted within Vsaid body and shorter than the body, a threaded plug closing one end of said body and maintaining said liner in spaced relation with said end, said liner loaded with ne strands of potassium nitrate, sulphur and charcoal in a nitrocellulose matrix, said strands in axial alignment with the liner and slightly shorter than the liner, a head of greater diameter than said body for closing the opposite end of the body, said 4 Y head having a reduced threaded portion adapted to be screwed into the body to maintain thev liner in position, Said head provided with a channel extending therethrough and open to said strands, a mushroom-shaped percussion primer with the umbrella portion facing away from said strands positioned in said channel in that portion of the head extending beyond said body, a firing plug within said channel of the head having a pin pointed toward the umbrella portion of the percussion primer and a battery cup securing said ring plug inposition in the channel of said closing head.

References Cited by tlie Examiner UNITED STATES PATENTS 1,901,469 3/33` Piccard 102--86-5 XR 2,424,993 8/ 47 Meister 102-86.5 2,516,898 8/50 vMeister 102-865 XR 2,853,007 9/58 Casati l-02-86.5 XR 2,995,088 8/61 Asplund 102-70 3,044,399' 7/ 62 Easton 102-70 FOREIGN PATENTS 51,264,862 5/61 France.

298,543 l0=/ 28 Great Britain.

OTHER REFERENCES Military Explosives, Department of the Army Technical Manual TM 9-l9l0, 1955 (pages 240 and 241 relied on).

SAMUEL FEINBERG, Primary Examiner.

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