US2666948A

US2666948A - Apparatus for the manufacture of plastic explosive pellets

Info

Publication number: US2666948A
Application number: US495084A
Authority: US
Inventors: Edgar G Guenther; Robert C Burton
Original assignee: Individual
Current assignee: Individual
Priority date: 1943-07-16
Filing date: 1943-07-16
Publication date: 1954-01-26
Anticipated expiration: 1971-01-26

Description

9 1954 E. G. GUENTHER ETAL 2,666,948

APPARATUS FOR THE MANUFACTURE OF PLASTIC EXPLOSIVE PELLETS Filed July 16, 1943 2 Sheets-Sheet 1 Edfl'ar' G- Guenther Robert E. Burton amen W010 I 1954 E. G. GUENTHER ETAL 2,666,948

APPARATUS FOR THE MANUFACTURE OF PLASTIC EXPLOSIVE PELLETS 2 Sheets-Sheet 2 Filed July 16, 1943 Patented Jan. 26, 1954 UNITED PATENT F 'F l CE Application July '16, 194$,Seri'al No. 495,084

101mm. 1 .Ihepresent invention relates g'enerallyto thermoplastic explosive compositions, and more particularly to an improved apparatus for casting andvpelleting the same.

Heretofore it has been common practice in manufacturing high explosives to produce "a flaked, grained, crystalline or-other free-flowing material which can be safely charged into'agitated mixing vessels having clearances of less than 1 inch. When pellets of single explosives pelletsof a size and shape whlchcanb'e remelte'd quickly and safely, and "which can he used "directly for pellet loading.

. Another object is the "p'rovisic'mor apparatus for producing free-flowing pellets from thermoplastic explosive compositions.

Other objects andadvantages willbe apparent as the invention is hereinafter-more 1 particularly described.

A preferred illustrative embodiment of the present invention is shown in the appended-drawing, wherein:

Figure 1 is-a side 'elevation of the p'e'lleti'ng apparatuszas-a whole;

Figure 2 is a sectionongtheimes z ofFigure '1;

Figure Sis a plan -of the extrusion vessel, the direction of belt movement and the pellet rows being indicated by the arrow and the dotted lines, respectively;

Figure 4 is a vertical cross section of the extrusion vessel shown in'Figure 3;

Figure 5 is a perspective view of an agitator for the extrusion vessel;

Figure 6 is a perspective view-of the scraper and apron at thedischar'geend of the apparatus shown in Figure 1-; and

Figure 7 is a perspective view of one of the formed pellets.

Referring particularly to Figure l, the apparatus comprises a machine bed or frame I supporting at each end, a rotatably mounted

pulley wheel

2 and 3,"o'ne-of which (2) isdriven in any suitable-manner, for example by means offabelt 2a passing-over pulley 2b. The two wheels-2 "and '3 carry'an'endless metallic belt 4 preferably made of stainless steel. Suitable supporting skids 5, preferably of wood, on the underside of the advancing belt-prevent the belt'fromwibrating'ahtl thereby obviate-the formation of disc' 'shapedpellets. The under side of the returning beltis supported by idle rollers 6, and a swinging 'belt "tightener roller Ga may be provided on 1 the 1 upper side ofthe returning belt. u

At the feed and of the be1t ,-a'steam jacketed ex- 'trusion kettle is supported a "suitabledistance above the beltl, onhkettlepracket-B. Th dis- "tance of the kettle I -'ahove-the-belt"4 is so ad- 'iusted that uniform droplets of explosive will'forin during the period of fall from the kettle to the belt.

The details of 'thelkettle are morefparticularly shown in Figures 3, 4 and 5. The kettle consists of two concentric 'n'e sted pots 20 and 2 l suitably united to form a single jacketed vessel. Suitable 'outlet and inlet ports 22 and 23 permitstearn to be introduced into the annular"spacebetween the pots Hand 21. The bottom of the-pot'is provided with "a number of extrusion holes, 2'4, uniformly spaced'and'arranged in the form of a circle which ar'e'also steam jacketed, as shown, the holes being so located as to provide a uniformly -spaced feed. A twisted-anchor agitator 25 provided with upturned ends 26 is connected to a hub 21 which has a socket connection with drive shaft 28, so that the pot contents maybe stirred duringpper ation. 5 Set screw ZSsecures hub-21 to drive shaft 28. Shaft 28 is rotatably supported in the upright- 12 (Fig.1) and adapted'to be'rotatedbythe pulley wheel H connected 'through'a V=be1t (not shown) to a suitable source for power- (not shown) for slowly rotating the agitator-shaft 28,

Above and below the advancingb'elt'li are disposed. suitable air ducts 12 and 13 provided with spaced air outlet slots!!! on the face adjacent to the advancing some that cool 'ainmayb'e blown against the upper andlowe'r surface-thereof. "Ifhe ducts I2 *and I3 are connected through conduits and [5 to air trunk a! which isconnectedivith a suitable pressure Tan (not shown).

At the discharge end or the "belt, a 'wooden scraper blade 11 is provided to remove anyexplosive pellets which adhere to the belt 4. The explosive pellets fall into a suitable hopper H, being collected on the apron l8 which desirably consists of; a frame covered with cloth 32 to cushion the fall.

In operation, the plastic explosive is placed in the steam jacketed extrusion vessel I wherein a constant level is desirably maintained in order to obtain drops of uniform volume. As the agitator 25 revolves, the plastic flows through the extrusion holes 24 and falls in the form of discrete globules 9 through the air onto the advancing belt 4. As the deposited droplets, supported on the belt, are carried forward between the upper and lower air ducts l2 and I3, they are gradually solidified. When the pellets reach the discharge end most of them slide onto the apron 18 or directly into the hopper l 6. Any pellets which adhere to the belt are removed by the scraper blade I! and thence fall into the hopper It.

By suitable adjustment of the plasticity of the explosive, the size of the extrusion holes 24, the depth of the plastic in the extrusion vessel 1, the height of the fall from the extrusion vessel 1 to the belt l, the cooling rate, the length of the belt etc., the explosive may be obtained in pellets of varying size and shape. Generally the pellets, in configuration, resemble an unopened rose bud, as shown in Figure '7, and are freeflowing.

As an example of the preparation of an explosive composition that may be formed into pellets according to the present invention, the following is given:

One hundred parts by weight of water is placed in a steam-jacketed mixing vessel provided with an efiicient stirrer and equipped with a hood for removing TNT fumes. 400 parts by weight of TNT is then added and the mixture agitated until the TNT is completely melted (15 pounds of steam pressure being applied in the jacket). After allowing the mixture to come to rest, the water separates and rises to the top of the molten TNT. About 705 to 750 parts by weight of moist cyclonite (15-20% moisture, corresponding to 600 parts of cyclonite on a dry basis) is then added slowly through the water layer which appears to disperse the cyclonite and permit rapid mixing with the TNT. After the cyclonite is all added, the mixture is stirred for about one-half hour and the water layer then decanted. Heating is continued for about one and one-half hours in order to vaporize all the water from the molten mass. During the foregoing operations, 15 pounds steam pressure is maintained in the jacket until the temperature of the molten composition reaches about 104 C. Thereafter, the steam pressure in the jacket is reduced to about pounds. By holding the molten composition about 104 C., is was found that the subsequent operation of wax incorporation is facilitated.

After the water is substantially completely removed from the TNT-cyclonite composition, 1% of a previously melted amorphous petroleum wax, for example Aristowax sold by Union Oil Co. of California, is mixed with the TNT-cyclonite mixture in the mixing vessel, while maintaining a mixture temperature of 104 C.

Preferably an agent for lowering the interfacial tension between the cyclonite and the amorphous wax is added to the amorphous wax before it is added to the TNT-cyclonite mixture. For this purpose a large number of long chain hydrocarbon derivatives containing polar groups (e. g., carbonyl, carboxyl, hydroxyl, etc.) may be used.

The long chain fatty acids such as stearic acid, for example, are illustrative of the type of interfacial adjuncts which are suitable. It is preferred, however, for economical and other reasons, to employ the crude mixture of polar compounds obtained by bubbling air through heated petroleum hydrocarbons (e. g., those derived from Pennsylvania crudes) in the presence of oxidation catalysts such as manganese oleate. The resulting water insoluble, oil-soluble, oxygen-containing petroleum derivatives consist of alcohol. ketone and carboxyl compounds as well as esters and probably some lactones, etc. These complex mixtures are available on the market under the trade name Alox, such as Alox-310, A101:- 350 and Alox-600. Alox-600 to the extent of about 10% by weight of the amount of the amorphous petroleum wax used is added to said wax before it is added, as above described, to the TNT-cyclonite mixture.

The proportion of cyclonite in the above described explosive composition may be varied, as will be understood by the person skilled in the art, and indeed, in some instances it may be desirable to increase the proportion of cyclonite to 62-63% by weight of the composition, in order to obtain a more workable composition.

The cyclonite referred to above is an explosive which has a molecular formula of CsHsOsNe, and a melting point in the pure state of approximately 205 C. It is considered to be cyclotrimethylenetrinitramine, and may be prepared by the method described by Hale in the Journal of the American Chemical Society, vol. 47, page 2754, issued in 1925.

In the foregoing detailed description, it will be apparent that many variations may be made without departing from the spirit and scope of the invention. We therefore intend to be limited only in accordance with the following patent claim.

We claim:

An apparatus for the manufacture of uniformly sized and shaped high explosive pellets comprising an extrusion chamber having its sides and bottom surrounded by steam jacketing forming therewith a steam space having inlet and outlet connections thereto, bottom openings in said chamber connected by pipe portions leading through said steam space and said jacket, a rotatably mounted S-shaped anchor agitator having upturned ends, said agitator cooperating with said pipe portions to move a plastic explosive composition therethrough, a flexible conveyor mounted beneath said chamber for receiving and moving said extruded material, supporting means for dampening the vibration of said conveyor while in motion, and means for cooling said ex-' truded material on said conveyor.

EDGAR G. GUEN'I'HER. ROBERT C. BURTON.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 450,591 Schrader Apr. 14, 1891 1,455,923 Minniberg May 22, 1923 1,469,316 I-Iartshorn Oct. 2, 1923 2,088,247 Paton July 27. 1937