US2455336A - Delay action initiator for explosive charges - Google Patents

Description

E. JONES DELAY ACTION INITIATOR FOR EXPLOSIVE CHARGES 3 Sheets-Sheet 1 zlwuwno'n )EL YN JON ES m JZ J. WM

Nov. 30, 1948.

Filed July 26, 1944 Nov. .30, 1948. E. JONES DELAY ACTION INiTIATOR FOR EXPLOSIVE CHARGES Filed July 26, 1944 3 Sheets-Sheet 2 g qdoo -LWY JONES ilfllliilll'llllllllll:

Nov. 30, 1948. E. JONES DELAY ACTION INITIATOR FOR EXPLO SIVE CHARGES Filed July 26, 1944 3 Sheets-Sheet 3 A I v EL YN JON/ES IlllllfllI/ll Ill Guam;

Patented Nov. 30, 1948 DELAY ACTION INITIATOR FOR EXPLOSIVE CHARGES Elwyn Jones, Ardrossan, Scotland, assignor to Imperial Chemical Industries Limited, a corporation of Great Britain Application July 26, 1944, Serial No. 546,666 In Great Britain February 15, 1943 1 Claim. 1

The present invention relates to the provision of delay action initiators for explosive charges, for instance, delay action detonators, which are adapted to be actuated by hand by an operator before he has left the position at which the explosive charge has been laid, or while he is still in its near vicinity.

The hand actuated delay action initiators made according to the present invention are especially, but not exclusively, useful for military demolition purposes, since in warfare it is possible for an operator to lay a demolition explosive charge with which the delay initiator has preferably been already assembled, in a required position at which he may be exposed to danger from the enemy, and thereafter in a mere moment actuate the delay action initiator and immediately make his escape to a position of safety from the explosion, and, if need be, back into cover from the enemy, no time being wasted at the exposed position in making electrical connection or the like for distant actuation. Moreover, if a number of demolition charges at wide distances apart are to be fired a considerable saving of time and material results from the fact that each delay action initiator comprises its own means of actuation.

For the proper functioning of a delay action initiator it is essential that the delay composition, which is commonly in agtube superposed on top of the instantaneously reactive composition constituting the top charge or sole charge as the case may be of the portion of the initiator interposed between the delay composition and the explosive, should be protected from the access of moisture; but except in the case of delay compositions yielding little or no gas as a result of their combustion it is also necessary to provide free venting means to the exterior in order to prevent the delay composition from racing as a result of the development of excessive gas pressure- A compromise between these requirements is usually efiected by the application over the vents of a waterproof coating or the like of a nature easily rupturable or combustible by the hot gases developed within the initiator by the delay composition or the means of the ignition thereof, which in the case of delay action electric blasting detonators for instance is an electric fuzehead actuated from a safe distance.

' The consequences of racing of the delay composition owing to excessive pressure development withinthe delay action initiator due to undue clelay in venting an early stage of the combustion of the delay composition would be disastrous to the operator in the case of a delay action initiato'r actuated by hand in the proximity of the explosive charge.

Moreover, if while still holding the delay action initiator immediately after performing the act necessary to start the combustion train the operator's hand should be seared by a jet of flame emerging through the vent, it is possible that his attention would be distracted for the moment from the urgent necessity of putting a safe distance between himself and the explosive charge.

The present invention comprises a delay action initiator having a disengageably fixed external hand actuation member which in its fixed position occludes the venting communication to the exterior from the interior of the combustible charge containing portion of the delay initiator with which it forms part of the waterproofed closure, and which has associated with it friction means that is held out of contact with a match composition located in said portion, while the hand actuation member is in said fixed position, and can frictionally cooperate with it to start the combustion train only after disengagement and retraction of the said member by one hand of the operator from the charge containing portion held in his other hand have broken the waterproof closure and established effective venting communication to the exterior.

According to one .form of the invention the venting communication to the exterior from the interior of the combustible charge containing portion is formed in the terminal wall thereof, and according to another form of the invention it is formed in the lateral wall thereof. In the latter case the combustible charge containing portion of the delay action initiator preferably has an external flame shield for the hand holding it. The

flame shield may advantageously be independent of the waterproof joint between the hand actuation member and the charge containing portion of the device.

The means by which the hand actuation member is disengageably fixed to the combustible charge containing portion preferably comprises a bayonet joint, screwed joint or other form of joint adapted to lock the hand actuation member at an inoperative position with respect to the charge containing portion when attached thereto.

The means by which the frictional co-operation starting the combustion train is effected after effective venting communication from the interior of the combustible charge containing portion has been established according to one form of the invention comprises a channeled match located in a coaxially perforated cup at the end asaasse of a space terminally bound by a coaxially periorated terminal wall, and a wire having a irictionally ineffective portion passing through the periorations in the terminal wall and cup and the channel in the match, and terminating in a frictionally effective coiled spring portion that is companying drawings. In these drawings Fig. 1 'is an axial section of one form of delay action detonator made in accordance with the invention. Figs. 2 to '7 are details of certain oi the component parts employed in the delay action detonator illustrated in Fig. 1 and whereof Fig. 5 is an and elevation of the delay action detonator. Fig. 8 is an axial section of another form of delay action detonator made in accordance with the invention and Fig. 9 is a detail of one oi! the components of the delay action detonator illustrated in Fig. 8. Fig. 10 and Fig. 11 are axial sections of further forms of delay action detonators made in accordance with the invention.

With reference to the form shown in Fig. 1 a metal detonator tube i has a circular external protuberance or rim 3 pressed out of it from the interior and contains a single or multiple detonator charge 2 pressed into it. 6 is a tube of paper or other suitably compressible material fitting tightly over an open-ended metal delay tube 6 into which has been pressed a delay iuze composition 1. 6 is an outward lip at the mouth at one end of the tube 5, and 20 an inward turnover at the other end. B is a collar of paper or like compressible material. 9 is a metal tube, closed at one end except for an axial pinhole, having lateral venting apertures ill and external protuberances I l, which are best seen in Fig. 2, which is a side view of the tube 9 seen from a direction at right angles to that from which the section in. Fig. 1 is viewed. it, also shown in Fig. 3, is a cup charged with a pellet 18 of match composition having an axial channel preferably tapering towards a pinhole in the base of the cup and this channel is broader than the pinhole. I5 is a tubular distance piece, also shown in Fig. 4, abutting with the wall of the cup i2. i6 is the coiled portion of a strong wire 18. In its normal state the coil is of sufficient diameter to be held out of contact with the match composition by the distance piece it.

It is a metal cap slidably fitting over the cap 8. The cap it has an axial pinhole through which the wire it can slide and has a tongue 22 cut out in it, under which the end of the wire can be tucked to form an attachment loop 2|, also shown in end view in Fig. 5 when the cap i6 has been fixed into the desired position. The tube 9, with the cup l2, the distance piece it, the cap it and the wire I8, of which last a portion passes through the terminal pinholes, is slipped over the paper collar 8 at the end of the detonator tube I and located in position with the aid oi the protuberance 3 and is tightly crimped as shown at IS. The

open end of the cap it has slots I! out, in it, as seen in Fig. 6, which is a side view or the cap it, seen from a different direction from that from which the section in Fig. 1 is viewed. These slots co-operate with the protuberances ii on the tube 8 in forming a. close bayonet Joint, held in its extreme position by the looping oi the wire l8, and thus fixing the position 0! the tube It so that it shuts oi! the venting apertures iii and locks the operating member in a safe position so that inadvertent operation cannot be eflected. The portion of the resulting assembly iromthe protuberance 3 to the end remote from the detonator is provided with a waterproofing costing not shown in the drawing. 23 is a flame guard having a slotted portion of reduced diameter 24, which is slipped on to the detonator tuba l, and crimped as shown at 25 so that its wider, portion overlaps the tube It.

In the alternative form shown in Fig. 8 the numbers i to 22 have the same significance as in Figs. 1 to 7. 28 is a metal delay extension tube having a terminal portion of enlarged diameter 21, optionally provided with venting apertures 28, and having near its narrower end an external circular protuberance or rim 2t. 30 is a tube of paper or other suitably compressible material fitting tightly round a metal delay tube 8i oi similar construction to the delay tube 5 in Fig. 1, filled with a delay iuze composition 82, not extending appreciably into the enlarged portion 21 of the extension tube.

The tube 8 and collar 9 are crimped over the narrow end oi the delay extension tube 28, as shown at $8,.and the broad end 0! this tube is crimped over a collar 34 of paper or other compressible material over the end of the detonator tube i as shown at in Fig. 8. The joints from the protuberance 3 to the wire loop end are waterprooied in the manner already described and the crimped joint at 35 and the venting orifices 28 are also waterprooi'ed. The slotted end 24 of the flame guard 28 is crimped over the extension tube as shown at 36.

In firing the delay ignition device, the operator holds the upper portion of the detonator tube or delay extension tube as the case may be in one hand, preferably by gripping the narrow portion as of the flame guard in his fingers. With the fingers of his other hand he grips the cap it, unflxes the bayonet joint and pulls the cap right off by means of an energetic tug. The unflxlng oi the bayonet joint destroys the waterproof seal. and the early part of the pull uncovers the venting apertures It before the distortion of the coiled portion M of the wire it enables it to slip through the distance piece l5 and so make frictional contact in its distorted state with the match pellet l3.

The flame guard 23 protects the fingers of the hand still holding the detonator tube or delay extension tube when the composition begins to burn from flame issuing through the venting apertures II). By this time the fingers holding the cap it will have been removed sufilciently far away to prevent them from being seared.

When a delay extension piece is used, it is not essential that it should have lateral vents such as are illustrated at 28 in Figs. 8 and 9, if the fuze composition I is of such a nature that it will not race when it is ignited under pressure. For instance the lateral vents may be omitted if the fuze composition I is formed from a mixture of oxidising and reducing agents yielding little or no gas as a result of its composition. Moreover these lateral vents may be omitted ii the iuze frictionally co-operates with composition 32 is of such a nature that the residue of' its combustion does not clog up the fuze composition 1. Some kinds of black powder fuze compositions are less liable than others to form a residue that prevents the relief of pressure by longitudinal escape of the gases.

With reference to Figures and 11, the numerals I to 6 and II to I3 and I8 have the same significance as in Fig. 8. I8 is a wire of which a coiled portion abuts against the end of the wall of the cup I2. This coiled portion I4 is not itself efiective to ignite the pellet l3 of match composition, and simply becomes extended and slips past the pellet without igniting the latter when the wire 18 is retracted through the orifice at the base of the cup i2, which is of sufllcient diameter to provide an effective gas vent when it is exposed by the removal of the disengageably fixed hand actuation member to which the wire 18 is permanently attached. 40 is a roughened and coiled portion of the wire l9 which provides a coil of smaller diameter than the portion 14, and the pellet l3 to ignite the latter after the coiled portion i 4 has been pulled out sufiiciently to bring this roughened and coiled portion into engagement with the pellet. 42 is a delay extension tube having a portion 43 of enlarged diameter and a rim 44; 37 is a spit composition and 38 a fuze composition. 45 is a paper tube, 46 is a metal delay tube charged with a spit composition 47 and a fuze composition 48. 49 and 52 are layers of sealing composition and 50 and BI are crimps. The fuze composition is one composed of a mixture of oxidising and reducing agents yielding substantially no gaseous products as a result of its combustion.

In Fig. 10 39 is a metal tube having a terminal aperture of about the same diameter as that of the cup II, but no lateral perforation in its wall.

. The cap I6 is similar to the cap illustrated in Fig.

5 and Fig. 6 except for the provision of corrugations 4| intended to facilitate its being gripped. The waterproof closure is provided by the blob of waterproofing material 53, and a waterproofing clip not shown at the other end of cap l8.

In Fig. 11, 54 is a metal cap accommodating the cup 12 and the threaded body ring 55 on opposite sides of a constriction therein. 56 is a threaded body plug forming a waterproof joint with the threaded body ring 55 with the aid of a layer of sealing composition 58. 51 is a solder anchorage for the wire l8 and 59 is a ring handle. In order to actuate the device the operator unscrews the body plug 56 by means of the ring 59 from the body ring 55 and retracts the body plug.

I claim:

A hand operated delay action initiator comprising a detonator tube, an explosive charge therein, in juxtaposition thereto a delay tube containing a delay composition, an ignition tube containing a co-axially perforated match composition and a friction ignition member passing through said perforation, said member having one end fastened to a slidable sheath surrounding said ignition tube, a portion of said member being frictionally ineffective, venting means in said ignition tube, said venting means being un-- covered only when the effective portion of said friction member contacts said match composition, safety means to prevent accidental sliding of said sheath, and an external flame shield surrounding said ignition tube. I

ELWYN JONES.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 379,147 Andrews Mar. 6, 1888 2,170,815 Eroe Aug. 29, 1939 FOREIGN PATENTS Number Country Date 17,343 Great Britain 1912 87,868 Austria Apr. 10, 1922 299,044 Germany Mar. 16, 1921 424,527 Germany Jan. 26, 1926 442,119 Germany Mar. 21, 1927 512,856 Germany Nov. 20, 1930 612,946 Germany May 8, 1935

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