US2986803A

US2986803A - Method and means for producing a low energy detonator

Info

Publication number: US2986803A
Application number: US69547A
Authority: US
Inventors: Richard H F Stresau; Harold J Plumley
Original assignee: Individual
Current assignee: Individual
Priority date: 1949-01-06
Filing date: 1949-01-06
Publication date: 1961-06-06
Anticipated expiration: 1978-06-06

Description

June 1961 R. H. F. STRESAU ETAL 2,986,803

METHOD AND MEANS FOR PRODUCING A LOW ENERGY DETONATOR 4 Sheets-Sheet 1 Filed Jan. 6, 1949 gvvumn bo'w R. H. E STRESAU H. J. PLUMLEY R. H. F. STRESAU ET AL June 6, 1961 METHOD AND MEANS FOR PRODUCING A LOW ENERGY DETONATOR Filed Jan. 6, 1949 4 Shee ts-Shee N @NE e/wton R. H. F STRES H. J PLUMLEY June 6, R, H. F, STRESAU ETAL METHOD AND MEANS FOR PRODUCING A LOW ENERGY DETONATOR 4 Sheets-Sheet 3 Filed Jan. 6, 1949 awe/whoa R. H. E STRESAU H. J. PLUMLEY W June 6, 1961 R. H. F. STRESAU ET AL METHOD AND MEANS FOR PRODUCING A LOW ENERGY DETONATOR Filed Jan. 6, 1949 4 Sheets-Sheet 4 Elma/whom R. H. F. STRESAU H. J. PLUMLEY METHOD AND MEANS FOR PRODUCING A LOW ENERGY DETONATOR Richard H. F. Stresau, Washington Grove, Md., and

Harold J. Plumley, Washington, D.C.

Filed Jan. 6, 1949, Ser. No. 69,547 20 Claims. (Cl. 29155.5) (Granted under Title 35, U.S. Code (1952), sec. 266) This invention relates to an electrical initiator for a detonator and more particularly to an apparatus for constructing and applying a low energy operated initiator to the end f a wire bridge type of detonator plug. The present invention provides a new and improved method and apparatus for securing a relatively fine wire or initiator to the end of a detonator plug by spraying molten metal thereon in which the bridge portion of the initiator 1s maintained at a predetermined effective length during the aforesaid spraying operation.

The invention further provides a method and apparatus for applying an initiator wire of relatively small diameter to the detonator plug in such a manner that only a small portion of the initiator wire is eifective'to ignite the exlplosive in response to an electrical impulse received there- One of the objects of the invention is the provision of a new and improved method and apparatus whereby an electrical initiator is applied and secured to a chemically treated end of the detonator plug. I

Another object of the invention is the provision of a new and improved apparatus for applying and securing a length of fine initiator wire to the detonator plug.

A further object of the invention is the provision of a new and improved device for controlling the effective length of the bridge portion of a fine wire initiator for a low energy detonator as the initiator is secured to the end of the detonator plug.

Other objects and many of this invention will be readily appreciated as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings wherein: I

the attendant advantages of FIG. 1 is a plan view of the device of the present invention and showing portions thereof broken away and in section;

FIG. 2 is an elevational view of the device of FIG. 1 and showing portions of the device broken away and in section; v I

FIG. 3 is an enlarged fragmentary sectional view of the device of FIG. 1 and showing a detonator plug arranged therein, before the top plate assembly supporting a length of initiating wire has been clamped to the plug holder assembly;

FIG. 4 is a view similar to FIG. 3 but showing the top plate ina clamped condition with respect to the plug holder and the initiating wire embedded in the end of the detonator plug; I

FIG. 5 is a detail sectional view taken on the line 55 of FIG. 3;

FIG. 6 is a diagrammatical view showing an arrangement whereby the initiating wire is secured to the end of the detonator plug by spraying the end of the plug with molten metal;

FIG. 7 is an enlarged sectional view of the top plate assembly and taken on the line 7--7 of FIG. 2;

\FIG. 8 is a view similar to FIG. 7 but taken on the line 8-8 of FIG. 2;

FIG. 9 is an enlarged end view of the detonator 'plug and the fine bridge wire initiator secured thereto;

FIG. 10 is a fragmentary sectional view taken on the line 10-10 of FIG. 9;

2,986,803 Patented June 6, 1961 FIG. 11 is a sectional view taken on the line 1111 of FIG. 10; and

FIG. 12 is an enlarged sectional view of a complete detonator and initiator therefor.

Referring now to the drawings for a complete understanding of the invention and more particularly to FIGS. 1 and 2, the device for applying the initiator wire to a detonator plug is generally indicated by the reference character 10, and comprises an elongated base or supporting member 11, composed of any material suitable for the purpose such, for example, as laminated Bakelite. The member 11 is provided with a plurality of bores 12 extending therethrough for slideably supporting a plurality of plug holders generally indicated by the numeral 13 and respectively arranged in bores 12, each plug holder comprising a shaft 14 respectively extending through bearings 20 formed in the member 11, and having a knurled knob 17 arranged on one end thereof and a head 18 adjustably secured to the other end as by threaded engage ment therewith, the head 18 being provided with a transversely arranged slot 19, FIGS. 3, 4 and 5. As shown on FIGS. 1 and 2, rotative movement of the heads 18 is prevented with respect to the shafts 14 by a plurality of screws and keyways respectively disposed in the member 11 and heads 18, indicated by the

numerals

21 and 22. It will be understood, however, that upon rotation of the knobs 17 the heads 18 will be slideably adjusted within the bores 12 by reason of the threaded connection between the shafts 14 and bores 23 formed in the heads 18. Surrounding the shafts 14 and having one end thereof in abutting engagement with the heads 18 respectively and the other end in abutting engagement with the bearings 20 respectively is a spring 24. By this arrangement the detonator plugs generally indicated by the numeral 26 are adjustably maintained in the desired position within the member 11, with the reduced end 27 on each plug extending a predetermined amount beyond the outer surface of member 11 such, for example, as .020 of an inch. Each plug is provided with a pair of spaced terminals 28 molded therein and extending therefrom, the terminals on each plug being respectively disposed within the slots 19 in heads 18 when the device is assembled and thus the plugs are maintained within the bores 12 in desired relation with respect to each other whereby the terminals on the plugs are in alignment as most clearly shown on FIG. 1.

In preparing each plug prior to the fabrication operation, the surface 31 thereof is ground, whereupon the plug is further prepared by etching the ground surface in an alkaline solution such, for example, as a 10% aqueous solution of potassium hydroxide. The etching operation is continued until the ground surface of the plug is rough and soft enough to assure a good adherent surface. When this has been done the plugs are arranged within the member or base 11 in the aforesaid manner with the reduced ends 27 thereof extending beyond the outer surface of the member whereupon the surface 31 of each plug is wiped with a cloth containing a copious amount of carbon tetrachloride, thus removing fingerprints, grease and dirt therefrom.

The initiator wire 30 comprising the bridge of the detonator plug is drawn very fine and etched, a wire having a diameter of .0001 to .00045 inch having been found satisfactory for the purpose. In applying the initiator wire 30 to the heretofore mentioned end portion of the plugs, a top plate assembly generally indicated by the reference character 32 is employed as more clearly shown in FIGS. 2, 7 and 8. The plate assembly comprises an elongated member 33, composed of any material suitable for the purpose such, for example, as steel and having a plurality of blocks 34 secured thereto as by screws 35 or the like, the initiator wire 30 being secured to and along 3. a common centerline of the under surface of the block assembly as by Scotch tape 36, FIGS. 1 and 2. Arranged between each block and in engagementtherewith is a shim 37. The blocks are provided With arcu'ate notches respectively formed in the outer surfaces thereof and arranged in such a manner as to form a plurality of holes 38 therebetween when the blocks are assembled, each hole being bisected by one of the shims 37 and in registration with a complementary bore 39 formed in member 33, the bores 39 terminating at a wall defining the bottom surface of a groove or guideway 41, FIGS. 1, 7 and 8. As more clearly shown on FIG. 1 the blocks and shims are secured together and drawn into abutting engagement with respect to each other by a pair of bolts indicated by the reference character '40, one end thereof being respectively threaded into bores arranged in the end block of the block assembly, the other end of each bolt having an enlarged head thereon and in abutting engagement with the outer surface of the other end block of the block assembly. As hereinbefore described the blocks are secured to the member 33 by screws 35. To provide a unitary top plate assembly after the blocks, shims and members have been assembled in the aforesaid manner, the shims are .Welded to the blocks 34 as at 50 and the member 33 is welded to the blocks as at 60, FIGS. 7 and 8. As shown more clearly on FIGS. 1 and 2 the top plate assembly 32 is guided into proper position with respect to member 11 by a pair of dowel pins 42, supported thereby and adapted respectively to engage a' pair of openings 43 formed in the plate assembly 32 and thus the shims are positioned at a right angle with respect to the common centerline of the top plate assembly and the initiator wire coincides therewith, the shims and wire intersecting at a point, FIG. 1. By reason of the aforesaid arrangement a portion of the ground and etched surface of each plug 26 is masked corresponding to the thickness of the respective shims thereforand the effective portion of the initiator wire 30 in alignment with the ends of each plug is also masked by the shims.

The length of this unmasked bridge portion is only sufiicient to cause the fine wire bridge to be heated to incande'scence in'response to the momentary application of electrical energy in the order of 50 ergs applied thereto from a suitable source such, for "example, as the voltage generating devices disclosed and claimed in the copending application of Harold J. Plumley for Magnetic Inertia Controlled Fuze, Serial No. 535,799, filed May 16', 1944,

now Patent 2,848,948. To achieve this result it is necesthe member 11 it is clamped in position thereon by a pair of clamping devices 45 respectively disposed on the ends thereof and comprising a'pair of clamp plates 46 maintained in clamping engagement withrespect to-the plate assembly by a pair of bolts 47 and wing nuts 48, FIGS;

land 2. When this has been done the wire 30'is forced into the ground and etched surfaces of each plug by the aforesaid spring and plug holder arrangement associated therewith, the prongs of eachplug respectively extending into the slots 13 in heads 18. When the aforesaidclamping operation has been completed the initiator wire is secured to the ground and etched end of the battery of plugs arranged therein in the following manner.

With particular reference to FIG. 6 the assembly 32 is supported in any suitable manner adjacent a metal spray gun 49 with the grooved surface 41 thereof outermost and in alignment with the gun nozzle '51, suchthat the molten metal sprayed therefrom is directed into the aforesaid holes or

openings

38 and 39 formed in the plate assembly 32 onto the ground and etched end of the plugs and thus securing of the wire to the plugs in electrical connection with the prongs is accomplished. It has been found that during the spraying operation the best results are obtained when the' discharge end of the nozzle is spaced substantially three inches from the work. It will be understood, however, that any means may be employed for supporting the spray gun in operative relation with respect to'the work which permits transverse movement thereof with respect thereto, such for example as a lathe generally indicated by the numeral 52, FIG. 6, the gun being secured to the movable carriage thereof by the tool post 53. It has further been found that the best spraying results are obtained when the traversing speed of the carriage to which the gun is secured is between 13 to 26 inches per minute and the spray wire 54 on reel 55 is automatically fed therefrom through the rear end of the gun in the usual manner in solid condition and discharged from the nozzle end 51 thereof into the aforesaid groove in a sprayed molten condition, the wire being composed of any suitable material for the purpose such, for example, as silver solder, brass, copper or the like.

The spray gun is provided with the usual three way valve 56 adapted to be adjusted in such a manner as to provide a suflicient amount of air, gas and oxygen pressure to cause proper combustion and sufiicient heat therefrom; at the'nozz le end of the gun to melt the wire as the wire is fed therethrough in the usual manner, the air, gas and oxygen connections to the valve being indicated by the

reference characters

57, 58 and 59.

After the spraying operation has been completed, the clamp devices 45 are released from clamping engagement with member 11 whereupon the top plate assembly is rocked sufi'lciently transversely to free it from the metal spray. When this has been accomplished the Scotch tape is removed from the top plate assembly and the plate removed from the member 11 thereby exposing the fabricated ends of each plug with the initiator wire 30 embedded therein by -the spray metal 60 except for the portions thereof respectively masked by the shims, it being understood, that the surplus portions of the wire be tween each of the plugs not coated by the spray operation is removed in any suitable manner preferably by cutting the wire on opposite sides of each of the plugs thereby providing an initiator 61 having a relative small bridge portion 62. When the cutting operation has been completed the plugs are readily removed from the member 11 by moving the plugs outwardly a predetermined amount beyond the outer surface of the member 11 by the aforesaid plug holder and spring arrangement respectively associated therewith after the plate assembly has been removed from the member 11;

In preparing the portion 27of the plug prior to securing the explosive cap 63 thereto, FIG. 12, it .is essential to chamfer or bevel the end portion of the plug including the spray metal 60 thereon as indicated at 64, FIGS. 10 and 11. When thislhas been-done the cap is secured to the portion 27 of the plug as by 'a pressfit therewith, FIG. 12, and, due to-the beveled portion thereof and by reason of the insulating washer 65 disposed within the cap and forced into engagement with the aforesaid spray metal 60 as the cap is pressed on portion 27, the possibility of a short circuit occurring between the aforesaid parts is eliminated.

The cap 63 is composed ofany material suitable for the purpose such, for example, as aluminum, the cap having a bore 66 arranged therein. Disposed within the bore 66 and surrounding the bridge 62 is an explosive charge 67 suitable for the purpose such, for example, 'as lead azide 'or the like, FIG. '12. It will be understood, however, that any suitable method maybe employed for loading the :c'ap with the aforesaid explosive such, for example, as pressing the explosive into the here under a predetermined {amount ofpressure.

From the foregoing description it will be apparent that a device and method is provided for applying and securguesses ing an electrical initiator of low impedance and low energy requirement to a detonator plug, in which the securing of the initiator to the end of a detonator plug is accomplished by spraying the end thereof with molten metal in such a manner as to cover the end of the plug and initiator except for a narrow strip masked by the edge of a relatively thin shim, and thus facilitating the application of a wire of small diameter to the end of a detonator plug and also controlling the effective length or bridge portion thereof whereby the low energy required to cause firing thereof is concentrated on a small quantity of the material comprising the initiator.

Obviously many modifications and variations of the present invention are possible in the light of the above teachings. It is therefore to be understood that within the scope of the appended claims the invention may be practiced otherwise than as specifically described.

The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor.

What is claimed as new and desired to be secured by Letters Patent of the United States is:

1. In an apparatus for applying a fine electrical initiator wire to an exposed end of a plurality of detonator plugs and in bonded relation with a pair of terminals arranged within each of said plugs, a base member for supporting said detonator plugs in spaced relation with respect to each other, means detachably secured to said base member for supporting a length of said wire thereon, said wire being adapted to intersect said exposed end of the plugs and said terminals at the center points thereof when the supporting means is secured to the base member, and a plurality of elements secured to the supporting means and respectively bisecting said exposed ends of the plugs at a right angle with respect to said wire for masking a portion of the wire and the end of each plug sufliciently to form a minute bridge portion thereon as molten metal is sprayed upon the exposed end of the plugs and on the terminals.

2. In an apparatus for applying a fine electrical initiator wire to an exposed end of a plurality of detonator plugs and in bonded relation with a pair of terminals arranged within each of said plugs, a base member, means for slidably supporting said plugs within said base member in predetermined spaced relation with respect to each other, means detachably secured to said base member for supporting a length of said wire thereon, said wire being adapted to intersect said exposed end of the plugs and said terminals at the center points thereof when the supporting means is secured to said base member, means on said plug supporting means for maintaining said exposed ends of the plugs and the terminals in engagement with said wire, and a plurality of elements secured to said supporting means and respectively bisecting the exposed ends of the plugs for masking a portion of the wire and of said end of each plug sufliciently to form a minute bridge portion thereon as molten metal is sprayed thereon and on the terminals.

3. In an apparatus for applying an electrical initiator to an exposed end of a plurality of detonator plugs and in bonded relation with a pair of terminals arranged Within each of said plugs and in face adjacency with respect thereto, a base member having a plurality of spaced bores extending therethrough, a plurality of actuating plungers slidably disposed within said bores respectively for supporting the plugs therein, a plate clamped to the base member and having a plurality of spaced openings extending therethrough and in registration with said bores, means for clamping said plate to the base member, a length of fine wire secured to said plate and adapted to intersect the bores, openings, and said pair of terminals at the center points thereof when the plate is clamped to the base member, means on the plungers for forcibly urging said end of the plugs and the terminals therein into engagement with said Wire when the bores and openings are in registration and the plate is clamped to the base member, and a plurality of'elements secured to the platefand respectively bisecting the openings therein for masking a portion of the wire'and of said end of the plugssufficiently to form a minute bridge portion thereon as molten metal is sprayed into the openings and upon the exposed ends of the plugs and the terminals.

4. In an apparatus for applying an electrical initiator to an exposed end of a plurality of detonator plugs and in bonded relation with a pair of terminals arranged within each of said plugs, a base member, said base member having a plurality of spaced bores extending therethrough, a plurality of actuating plungers slidably disposed within said bores respectively, means on said plungers for supporting the plugs thereon, a plate detachably clamped to the base member and having a plurality of openings extending therethrough and in registration with the bores respectively, means for clamping said plate to the base member, a length of fine wire secured to said plate and adapted to intersect the bores, openings and said terminals in the plugs at the center points thereof when the plate is clamped to the base member, means on the plungers for forcibly urging said end of the plugs and the terminals therein into engagement with said wire when the bores and openings are in said registration andthe plate is clamped to the base member, and a plurality of elements secured to the plate and respectively bisecting said openings therein and the bores in the base member for masking a portion of the wire and of said end of the plugs sufliciently to form a minute bridge portion thereon as molten metal is sprayed into the openings and upon the exposed end of the plugs and on the terminals.

5. In an apparatus for applying an electrical initiator to an exposed end of a plurality of detonator plugs, a base member having a plurality of spaced bores extending therethrough, a plurality of plugs respectively disposed Within said bores, each plug having a pair of terminals disposed therein and extending therethrough, a plurality of actuating plungers slideably disposed within said bores respectively, means on each plunger and in engagement with said pair of terminals on each plug for supporting the plugs, a plate having a plurality of spaced openings extending therethrough and in registration with said bores when the plate is clamped to the base member, means for clamping said plate to the base member, a length of fine wire secured to the plate, resilient means disposed on the plungers for forcibly urging said ends of the plugs and the pair of terminals respectively disposed therein into engagement with said wire when the plate is clamped to the base member, and means secured to the plate and respectively bisecting the openings therein and the bores in the base member for masking a portion of the wire and of said end of the plugs sufiiciently to form a minute bridge port-ion thereon as molten metal is sprayed into the openings and upon the exposed ends of the plugs and the terminals.

6. In an apparatus for applying an electrical initiator to one end of a battery of detonator plugs and in bonded relation with a pair of terminals disposed therein and extending through each of said plugs, a base member having a plurality of spaced bores extending therethrough, a plurality of plungers slideably arranged within said bores respectively, means including a slot arranged in each of said plungers and in engagement with said pair of term-inals for supporting one of said plugs thereon and within the bores respectively, a plate detachably clamped to said base member and having a plurality of spaced openings therein in registration with said bores, a length of fine wire secured to said plate and respectively intersecting the exposed end of the plugs, and means including a plurality of members-secured to said base member and bisecting said bores and openings for masking a portion of the wire and of the end of the plugs sufliciently to form a minute bridge portion thereon as molten metal is sprayed into said openings and upon the exposed ends of the plugs and the terminals.

7. In an apparatus for applying an electrical initiator to an exposed end of 'a plurality of detonator plugs and in bonded relation with a pair of spaced terminals disposed within and extending through each of said plugs, a base member, said base member having a plurality of spaced bores extending therethrough, a plurality of plungers slideably arranged within said bores respectively for supporting said plugs, means including a plurality of slots arranged in the plungers for respectively receiving a pair of said terminals thereby to prevent rotation of the plugs Within the bores, a plate having a plurality of spaced openings extending therethrough and in registration with said spaced bores respectively when the plate is clamped to said base member, means for detachably clamping said plate to the base member, a length of fine wire secured to said plate, resilient means arranged in each of the bores and in abutting engagement with the plungers therein for forcibly urging said end'of the plugs and said terminals into engagement with said wire when the plate is clamped to the base member, and a plurality of elongated devices secured to the plate and bisecting the openings therein and said bores for masking a portion of the wire and of said end of the plugs sufliciently to form a minute bridge portion thereon as molten metal is sprayed into the openings and upon the exposed ends of the plugs and the terminals.

8. In an apparatus for applying an electrical initiator to one end of a battery of detonator plugs and in bonded relation with a plurality of terminals arranged in pairs, each of said pairs being disposed within a plug and extending therethrough, a base member having a plurality of spaced bores extending therethrough, a plurality of plungers slideably arranged within said bores respectively, means on said plungers and in engagement with a pair of said terminals for supporting the plugs thereon and within said bores respectively, a plate detachably clamped to said base member and having a plurality of spaced openings therein in respective registration with said bores, a plurality of complementary members secured in closely spaced alinement to said plate, each of said members having an arcuate notch provided therein in registration with respect to the notch of an adjacent member whereby said notches are alined with said bores and openings, a length of fine Wire secured to said members, and a plurality 'of devices disposed between each of said complementary members adjacent said notches and bisecting the bores and openings for masking a portion of the Wire and of said end of the plugs sufiiciently to form a minute bridge portion thereon as molten metal is sprayed into the opening and upon the exposed ends of the plugs and the terminals.

9. A device for applying a fine electrical initiator wire to an exposed end of a detonator plug and in bonded relation with a pair ofterminals disposed therein and extending therethrough, a base member, means including said terminals for supporting the plug within said base member and in engagement with said initiator wire, and means bisecting said end of the plug at a right angle with respect to the initiator wire for masking a portion of the wire and of said end of the plug sufiiciently to form a minute bridge portion on the initiator wire as molten metal is sprayed upon the end of the plug and on the terminals.

10. A method of securing a low energy fine wire initiator to the end of a detonator plug and to a pair of spaced terminals disposed therein which comprises etching said end of the plug sufficiently to produce an adherent surface thereon, applying a length of said wire to said end of the plug and to the terminals, masking a portion of the etched end of the plug and a minute portion of said wi-re intermediate the terminals, and thereafter spraying the unmasked portion of the etched "end of the plug, the

wire and the terminals with molten metal sufficiently to secure the wire to the plug and to the terminals.

11. A method of securing a low energy fine wire initiator to the end of a detonator plug and to a pair of spaced terminals disposed therein which comprises etching said end of the, plug with a 10% aqueous solution of potassium hydroxide sufilciently to produce an adherent surface thereon, applying a length of said Wire to the end of the plug and to the terminals, masking a portion of the etched end of the plug and a minute portion of the wire intermediate the terminals, applying force to the plug sufficient to cause the wire, to be embedded in said etched end and to engage the terminals, and thereafter spraying the unmasked portion of the etched end of the plug, the terminals and the wire with molten metal.

12. A method of securing a low energy fine wire initiator to the exposed end of a detonator plug and to a pair of spaced terminals disposed therein which oomprises etching said end of the plug with a 10% aqueous solution of potassium hydroxide suificiently to produce an adherent surface thereon, arranging said wire superficially with respect to said exposed end of the plug and said terminals, masking a portion of said etched end of the plug and a minute portion of said wire intermediate the terminals, applying force to the plug sufiicient to cause the wire to be embedded in the etched end of the plug and engage the terminals, and thereafter spraying the unmasked portion of the etched end of the plug, the terminals and the Wire with molten metal.

13. A method of securing a low energy fine wire initiator to the exposed end of a detonator plug and a pair of spaced terminals disposed therein which comprises etching said end of the plug with a 10% aqueous solution of potassium hydroxide sufiiciently to produce an adherent surface thereon, arranging said wire in such a manner as to intersect said etched end of the plug and said pair of terminals, masking a portion of the etched end of the plug and a minute portion of the wire, applying sulficient pressure to the plug to maintain the wire in engagement with said terminals and cause the wire to be embedded in the etched end thereof, and thereafter spraying the unmasked portion of the etched end of the plug, the terminals and the wire with molten metal.

14. A method of securing a low energy initiator wire to the exposed end of a plurality of detonator plugs and a pair of spaced terminals respectively disposed therein which comprises etching said end of each plug sufiiciently to produce an adherent surface thereon, arranging a length of said wire in such a manner as to interswt said etched end of the plugs and said terminals, respectively masking a portion of each of the plugs and portions of said wire, and thereafter spraying the unmasked portion of the etched end of each plug, the terminals and the wire with molten metal.

15. A method of securing a length of fine initiator wire to the end of a plurality of detonator plugs and to a pair of spaced terminals respectively disposed therein which comprises etching one end of each plug sufiicient- 1y to produce an adherent surface thereon, arranging said wire in such a manner as to intersect the etched end of the plugs and said pair of terminals therein, masking a portion of each of the plugs and of the wire, applying sufficient pressure to the plugs respectively to maintain the wire in engagement with said terminals and to cause a portion of the wire to be embedded in the etched end of the plugs, and spraying the portions of the etched end of each plug, the terminals and the Wire with molten metal.

'16. A method of securing a length of fine initiator wire to the end of a plurality of plugs and to a pair of spaced terminals respectively disposed therein which comprises etching one end of each plug with a 10% aqueous solution of potassium hydroxide sufiiciently to produce an adherent surface thereon, arranging a length of said wire in such a manner as to respectively intersect the etched end of each plug and said pair of terminals therein, respectively masking a fractional portion of the etched end of the plugs and of the wire intermediate said pair of terminals, applying sufiicient pressure respectively to the plugs to cause a portion of the wire to be embedded in the etched ends thereof and in engagement with said pair of terminals, and spraying the unmasked portion of the wire and of the etched ends of each plug including the pair of spaced terminals therein with molten metal.

17. An apparatus for securing a length of fine initiator wire to an etched end of a plurality of detonator plugs and to a pair of spaced terminals respectively disposed in said plugs which comprises means supporting the plugs with the etched end thereof exposed, means arranging a length of initiator wire in such a manner as to intersect the etched end of each plug and said pair of terminals therein, means masking a fractional portion of the etched end of the plugs and of the wire intermediate said pair of terminals, means applying sufiicient pressure to the plugs to cause a portion of the wire to be embedded in the etched end thereof and in engagement with said pair of terminals, and means adapted to spray the unmasked portion of the wire and the etched end of each plug including the pair of spaced terminals therein with molten metal.

18. A method for securing a length of fine initiator wire to the end of a plurality of plugs and to a pair of spaced terminals respectively disposed in said plugs which comprises etching one end of each plug sufiiciently to produce an adherent surface thereon, supporting the plug with the etched end thereof exposed, arranging a length of initiator wire in such a manner as to intersect the etched end of each plug and said pair of terminals therein, masking a fractional portion of the etched end of the plug and the wire intermediate said pair of terminals, applying sufiicient pressure to the plug to cause a portion of the wire to be embedded in the etched end thereof and in engagement with said pair of terminals, and spraying the unmasked portion of the wire and the etched end of each plug including the pair of spaced terminals with molten metal.

19. An apparatus for securing a length of fine initiator wire to an etched end of a plurality of detonator plugs and to a pair of spaced terminals disposed in said plugs which comprises means supporting the plugs with the etched end thereof exposed, means positioning a length of initiator wire in such a manner as to intersect the etched end of each plug and said pair of terminals therein, means masking a fractional portion of the etched end of the plug and of the wire intermediate said pair of terminals and means situated to spray the unmasked portion of the wire and the etched end of each plug including the pair of spaced terminals therein with molten metal.

20. A method of securing a length of initiator wire to an etched end of a plurality of detonator plugs and to a pair of spaced terminals disposed in said plugs which comprises supporting the plugs with the etched end thereof exposed, positioning a length of initiator wire in such a manner as to intersect the etched end of each plug and said pair of terminals therein, masking a fractional portion of the etched end of the plug and the wire intermediate said pair of terminals, and spraying the unmasked portion of the wire and the etched end of each plug including the pair of spaced terminals therein with molten metal.

References Cited in the file of this patent UNITED STATES PATENTS 1,612,479 Wellhauser Dec. 28, 1926 2,005,897 Knowles June 25, 1935 2,107,903 Peters Feb. 8, 1938 2,182,968 Lunsford Dec. 12, 1939 2,260,558 Caughey Oct. 28, 1941 2,365,539 Flowers Dec. 19, 1944 2,387,083 McCain Oct. 16, 1945 2,393,780 Johansson Jan. 29, 1946 2,445,874 De Boisblanc July 27, 1948 2,466,890 Gilbertson Apr. 12, 1949 OTHER REFERENCES Stee magazine, September 15, 1947, pages 96 and article by Collier.