US2441248A - Fast burning delay fuze - Google Patents

Description

y 11, 1943- s. MORRIS ET AL FAST BURNING DELAY FUZE Filed NOV. 20, 1942 Georgia M 01-1 3 John L Owl/Jen.

ATTORNEY IN VEN TORS nasal May 11, 1948 PATENT OFFICE FAST BURNING DELAY FUZE George Morris, Ardrossan, Scotland, and John London, Preston, England, assignoro to Imperial Chemical Industries Limited, a corporation oi Great Britain Application November 20, 1942, Serial No. 466,378 In Great Britain August I, 1941 6 Claims. (Cl. 102-86.5)

The present invention relates to the provision of last burning delay iuzes for military or other pes for which there may be required mechanically robust fuzes, for instance bomb fuzes, shell iuzes, grenade iuzes and the like, having burning speeds more rapid than those that can be obtained from any compressed composition 01' the nature oi a black powder. Considerable difllculty has hitherto been experienced in finding suitable materials for use in preparing mechanically robust fuses having burning speeds faster than those obtainable by means of compressed black powder, and especially when the burning time required is less than can conveniently be arranged when compressed black powder is used, c. g.,less than 0.15 second, for which a compressed blackpowder fuze would be of too short a length for practical purposes.

It has been proposed to employ for the manufacture of slow or rapid burning fuze certain basic lead salts of low-nitrated nitro-compounds, or isomorphous mixed salts or crystal combinations thereof one with the otheror with multiple basic, partly basic, or neutral salts produced by the action of one or more intro-compounds or an alkali salt thereof upona non-explosive lead salt solution; and in particular to use for .this purpose basic lead salts of the dinitrocresols. dlnitrophenols and picraminic acid.

We have found that in the compressed train dorm the monobasic lead salt of 4:6 dlnitroresorcinol, is distinguished from the aforesaid lowly nitrated basic lead salts by the exceptionally rapid rate at which it burns without detonating, and its suitability for the purpose of prepar= ing mechanically robust fast burning delay fuzes as aforesaid. Q

According to the present invention therefore we employ in the production oi fast burning robust iuzee' a compressed composition comprising the monobaslc lead salt of 4:6 dlnitroresorclnol.

In the form in which the monobasic lead salt 01 as dlnitroresorclnol is ordinarily obtained as a result of its precipitation from solutions of a water soluble normal salt of 4:6 dlnitroresorclnol and theappropriate quantities of a water soluble eezplosive normal lead salt and a soluble w as. described hereinafter, it has poor runhing properties. For convenience in loading it i'ae' aordlngiy desirable to corn it with the assistonce Oi-161M611 percentage of an adhesive such M slim-arable. About 1 to 5 per cent. of the adhesive mayconveniently be used. The material also tends to stick to the punches used in loading the fuses, and it is therefore desirable to include a small percentage of a lubricant in the composition, preferably as a surface coating.

Thus the surface of the corned material may advantageously be coated with about 2 to 6 per 5 cent. of its weight of graphite.

' Monobasic lead salt of 4:6 dlnitroresorclnol may be obtained by causing a water soluble normal salt of 4:6 dlnitroresorclnol to react in aqueous solution with the amount of a water soluble lead salt theoretically required for its formation, in presence of not more than the calculated amount of a soluble base. The soluble normal salt of 4:6 dlnitroresorclnol may conveniently be a sodium, potassium, ammonium, calcium, or magnesium salt. The soluble base may be, for instance, sodium hydroxide, potassium hydroxide or ammonia; and the soluble lead salt may be, for instance lead nitrate or normal lead acetate. Instead-of the normal lead salt there may 29 be employed a soluble basic lead salt, e. g., basic lead acetate, but in this case the additional base is omitted or correspondingly reduced in amount. Preferably a solution of the water soluble normal lead salt is introduced gradually with agitation into an aqueous solution containing the dissolved salt of the 4:6 dlnitroresorclnol and the free base employed, and it is desirable to agitate the mixture for some time after the solutions have been mixed. While satisfactory results 30 can be obtained at atmospheric temperatures, the use of elevated temperatures is advantageous since it facilitates the occurrence of the preclpitated basic lead salt of 4:6 dlnitroresorclnol in more easily filterable form.

The quantities of the reagents required may be calculated from the following equation, wherein n is a measure of the basicity of the precipitated salt, and which is applicable to the case in which the sodium salt of 4:6 dlnitroresorclnol is caused to react with lead nitrate in presence of sodium hydroxide.

CeHz(NO-s) :(ONa) 2+ (12+ 1) Pb (N03 2+2nNaOH= CeHs(NO2) 2 (OrPb) +2 (n+1) NaNOa-l-nHzO 4 The basic lead salt of 4:6 dlnitroresorclnol may 5 be separated from the supernatant liquor, washed with water, advantageously used warm, e. g., at a temperature oi! --55 0., and dried at a temperature not exceeding about C. If desired the drying may be assisted by displacing the 50 water in the wet preparation by a neutral volatile organic liquid such as. alcohol, and evaporating oi the volatile organic liquid. The lead content of the ,monobasic lead salt of 4:6 dlnitroresorcinol, as is frequently experienced in the preparation of basic lead salts of other polyhydric phenolic compounds, may vary slightly from the value calculated for its anhydrous form according to the precise conditions of the preparation, a fact which may be attributed to a varying degree of hydration of the compound. As prepared by the method hereinbefore described the lead content usually lies somewhat below that corresponding to the anhydrous form of the salt, more particularly 62-64 per cent.

To obtain a robust fuze of the maximum burning rate the composition should consist, apart from its content of coming agent and lubricant, wholly of the monobasic salt of 4-: 6. dinitroresorcinol; but if somewhat slower fast burning fuzes are required it may advantageously comprise a proportion of a slower burning lead salt of a dinitrophenolic compound. As in the case of the aforementioned prior proposal this may be pres ent in the form of a mixed salt or crystal combination produced by co-precipitation with the monobasic lead salt of 4:6 dinitroresorcinol. For instance. there may be employed a co-precipitated mixture of the monobasic lead salts of 4:6 and 2:4 dinitroresorcinols with the former pre= dominating, corned and surface coated with graphite.

In putting the invention into effect, the material is pressed into the robust tubes employed in one or more increments, at a suitably high pressure, for instance to 14 tons per square inch.

The invention may be understood more readily by referring to the accompanying drawing which is a view in cross section of the fuze as claimed. In this drawing, l is a striker, 2 a threaded and channeled retaining nut for a percussion detonator 6. 6 is a threaded fuze body in which is accommodated a threaded and internally shouldered delay tube of stout metal construction into which has been compressed the delay fuze composition 6. i is a detonator capable of initiation from the iuze composition 6. 8 is a diaphragm of thin. metal and 9 is a pellet primer of a detonating explosive sensitive to initiation by the detonator i, and capable of transmitting a strong detonating impulse to a further charge of detonating explosive relatively less sensitive to initiation, not

shown, through the wall of the threaded pellet container ill. The explosive I may be for instance compressed tetryl.

The fuzes can be ignited by the flame from a percussion cap or electric fuzehead of the ordinary type.

Example 1 A steel tube having an external diameter of 5.08 millimetres and an internal diameter of 3.81 mm. and 31.75 mm. length is loaded under a pressure of 10 tons per square inch with four or five substantially equal small portions of a corned composition consisting of 98 per cent. monobasic lead 4:6 dinitroresorcinate, of lead content 64 to 66 per cent. and 2 per cent. gum arabic, surfacecoated with 2 to 6 per cent. graphite. The quantity of the composition that can be conveniently loaded into the tube amounts to about 0.85 gm., and the burning time of the resulting fuze is 0.12 second. The length of the tube filled by the composition is 17 mm.

Example 2 The procedure is the same as in Example 1 except that the corned composition employed consists of 98 per cent. of a mixture of monobasic lead dinitroresorcinates, of lead content 62 to 66 per cent, and 2 per cent. gum arabic, surfacecoated with 2 to 6 per cent. graphite, this mixture of monobasiclead salts being obtained by precipitation from a solution containing sodium 4:6 dinitroresorcinate and sodium 2:4 dinitroresorcinate in the ratio 4:1. For this purpose 28 parts 4:6 dinitroresorcinol and '7 parts 2:4 dinitroresorcinol are dissolved in a solution containing 28 parts sodium hydroxide in 1400 parts hot water, and into the resulting solution there are introduced over the course of 38 minutes 116 parts of a 10 per cent. solution of lead nitrate with agitation, the reaction temperature being maintained at 47 C. The mixture is stirred for a turther 15 minutes and allowed to settle, whereupon the supernatant liquor is decanted oif and the yellowish brown precipitate is washed with cold water at about 40 C. until the washings are free from sodium nitrate. It is then washed with alcohol and dried at 35 to 40 C. The resulting fuze has a burning time of approximately 0.16 second.

Example 3 The procedure is the same as in Example 1 except that instead of monobasic lead 4:6 dinitroresorcinate, of lead content 64 to 66 per cent., there is used a mixture of monobasic lead 4:6 dinitroresorcinate and monobasic lead 2:4 dinitroresorcinate in the ratio 4:1 by weight, each of these salts having a lead'content of 64 to 66 per cent. The two salts are separately prepared and dried off before they are mixed, and the mixture is then corned and coated with graphite as in Example 1. The burning time of the resulting fuze is 0.15 second.

Example 4 A cupro-nickel tube of dimensions similar to that used in Examplel is charged with 0.15 gram of corned and graphited monobasic lead 4:6 dinitroresorcinol as used in Example 1. The thickness of the charge pressed under a pressure or 10 tons per square inch is 3 mm. and the burning time of the resulting fuze is 0.025 second.

Example 5 A cupro-nickel tube similar to that described in Example 4 is employed. The composition employed is a co-precipitated mixture of the monobasic lead salts of 4:6 and 2:4 dinitroresorcinal and is the same as that described in Example 2. The weight of the charge is 0.25 gram and the length of the tube occupied by the composition compressed at 10 tons per square inch is 5 mm. The burning time is 0.06 second.

Example 6 A cupro-nickel tube similar to that employed in Examples 4 and 5 is used. The composition consists of a mixture made from a monobasic lead salt of 4:6 dinitroresorcinate having a lead content or 64 to 66 per cent. and a monobasic lead salt of 2:4 dinitroresorcinol which are mixed together in the dry state in the ratio 3:2 and then corned and graphited as described in Example 8. A charge amounting to 0.5 gram composition loaded'into the tube in two substantially equal portions under a pressure of 10 tons per square inch occupies 10 mm. of its length and the burnin: time of the resulting fuz is 0.15 second. In place of steel tubes or cupro-nickel tubes there may be used tubes of other rigid material, for instance other metals or alloys, synthetic resin, vulcanized fibre or the like. Mechanically robust composition comprising the monobasic lead salt of 4:6 dinitroresorcinol in compact form as a f result of pressing the same into saidtube.

2. A fast burning delay. fuze comprising a tube of rigid material and contained in said tube a a composition comprising the monobasic lead salt of 4:6 dinitroresorcinol in compact form as a result of pressing the same into said tube under a pressure of to 14 tons per square inch.

3. A fast burning delay fuze comprising a tube of rigid material'and contained in said tube a composition comprising the monobasic lead salt of 4:6 dinitroresorcinol in compact form as a result of pressing the same into said tube, said lead salt having a. lead content of from 64% to 66%.

4. A fast burning delay fuze comprising a tube of rigid material and contained in said tube a composition comprising the monobasic lead salt of 4:6 dinitroresorcinol and'a slower burning lead salt of a dinitrophenolic compound in compact form as a result of pressing the same into said tube.

5. A fast burning delay fuze comprising a tube of rigid material and contained in said tube a composition comprising the monobasic lead salt of 4:6 dinitroresorcinol and the monobasic lead salt of 2:4 dinitroresorcinol. in compact form as a result of pressing the same into said tube.

6. A fast burning delay fuze comprising a tube of rigid material and contained in said tube a composition comprising a. co-precipitated mixture of the monobasic lead salt of 4:6 dinitrorescorcinol and 2:4 dinitroresorcinol in compact form as a result of pressing the same into said tube.

GEORGE MORRIS. JOHN LOUDEN.

,EFEEENCES CITED The following references are of record in the file of this patent: I

UNITED STATES PATENTS Number Name g Date I 1,253,947 Casanovas Jan. 15, 1918 2,116,514

Hale et a1 May 10, 1938

Images