US3437038A

US3437038A - Process and assembly for manufacture of cast boosters,and booster product

Info

Publication number: US3437038A
Application number: US674337A
Authority: US
Inventors: Philip G Newman
Original assignee: Hercules LLC
Current assignee: Ireco Inc
Priority date: 1967-10-10
Filing date: 1967-10-10
Publication date: 1969-04-08
Anticipated expiration: 1986-04-08

Description

Apnl 8, 1969 P. G. NEWMAN 3,437,038

PROCESS AND ASSEMBLY FOR MANUFACTURE OF CAST BOOSTERS, AND BOOSTER PRODUCT FMed on. 10, 1961' Sheet I of 2 FIG. 3

I30 Ho 24 I30 Ho 24 I00 I30 H024 1 l I l 1 1 I PHILIP G. NEWMAN INVENTOR.

8Y5 MM ATTORNEY Aprll 8, 1969 P. G. NEWMAN 3,437,038

PROCESS AND ASSEMBLY FUR MANUFACTURE OF CAST BOOSTERS. AND BOOSTER PRODUCT Filed Oct. 10, 1967 Sheet 2 of 2 lOb FIG. 6B

FIG. 7A FIG. 7B

PHILiP G, NEWMAN INVENTOR.

BY S gym/W ATTORNEY United States Patent ABSTRACT OF THE DISCLOSURE The invention provides (1) a casting method for the manufacture of booster type initiators (2) integral molding assembly therefor (3) a resulting plurality of booster type initiators as an integral unit for storage, Shipping and the like, and (4) individual booster type initiators.

The process The steps of castng booster type explosives in each of a plurality of adjacently disposed integrally joined molds,

generally with primary initiator support means in each mold; and detachably supporting the molds of cast explosive in the integral unit.

The molding assembly A plurality of integrally joined open end molds, each generally containing primary initiator support means for a booster explosive, and means within the integral construction for detachably supporting the individual molds in the integral relationship, preferably a line of perforations intermediate open ends of adjacent mold members.

The integral unit of initiators Resulting detachably supported plurality of booster type initiators, each of which constitutes not only the cast explosive but also the mold in which it was formed, and is detachable from the integral unit for use without need for separation of the cast explosive from the mold.

The individual initiators Booster type initiators constituting the cast explosive, in the mold in which it was formed, generally with primary initiator support means therefor, detached for use from the above described integral unit.

This invention relates to a casting process for the manufacture of booster type initiators for explosives. In one aspect this invention relates to a molding assembly of integral construction for the manufacture of booster type initiators. In another aspect this invention relates to a plurality of cast booster type explosive charges integrally supported as separate units in a molding assembly above described and to resulting booster type initiators, individually detachable from the molding assembly, and each comprising the cast booster charge together with the mold in which it was formed, ready for firing without the need for separation of the booster charge from the mold. In still another aspect this invention relates to individual cast booster type initiators, including the booster charge and the molds in which they were formed, individually detached from a mold assembly above described. Other aspects of the invention will be apparent in light of the accompanying disclosure and the appended claims.

A complete explosive assembly ready for firing comprises a main explosive charge and means for initiating detonation of same. One such complete assembly comprises a combination of a cap-insensitive charge as a main explosive charge, a booster unit containing a booster type explosive charge as a secondary initiator, and an electric blasting cap or a detonating fuse as the primary initiator.

3,437,038 Patented Apr. 8, 1969 The booster charge is detonated in response to actuation of the primary initiator, and the main charge is detonated in response to detonation of the booster charge, to provide the full explosive force of the assembly.

Booster type initiators for explosives generally comprise a closed shell and a booster type explosive charge therein together with means for support of a primary initiator, such as a blasting cap and/or a detonating fuse, in detonating relationship with the booster charge. Usually, a well extending in the booster charge, and/ or one or more tunnels extending through the booster charge, or a combination of both, serves to support a blasting cap or detonating fuse or a combination of the two. Dependent upon the particular booster charge, a blasting cap may be sufficient as the primary initiator. However, the blasting cap may be utilizable with one or more strands of detonating fuse, or, One or more strands of detonating fuse may be utilized independently of the use of a blasting cap. In all events, such a booster assembly generally contains a single well, and/or one or more tunnels depending upon the need at hand. In some instances a small portion of supplemental explosive or inner sensitizer" of sensitivity greater than that of the booster charge is present as an insert in the booster charge in detonating relationship with the primary initiator and in turn with the booster charge to facilitate detonation of the booster charge in response to initiation of the primary initiator.

Heretofore in the manufacture of cast booster initiators, the practice has been to individually cast each booster charge together with the initiator support means therefor which has required separate handling of the individual units during the molding and packing operations and then during handling at the shooting site. This has of course necessitated additional man power, equip ment and time requirements to which the industry has been committed.

This invention is concerned with a molding assembly, method for manufacture, and product, in accordance with which a plurality of booster type explosive charges can be cast, packed, stored, shipped, and further handled as integrally supported elements of the molding assembly, thereby eliminating the need for individual handling during those operations; with a resulting plurality of booster type initiators, each comprising a cast charge, above described, in the mold in which it was formed, and readily detachable from the molding assembly for firing without need for separating the booster charge from the mold; and with individual booster type initiators thus detached from the unit.

In accordance with the invention a process is provided for the manufacture of booster type initiators which comprises casting a mass of booster type high explosive in each of a plurality of separate, but integrally joined, molds; and detachably supporting the resulting plurality of separate molds and product therein, in said integral joined relationship, along lines extending intermediate adjacent mold members. In preferred practice the booster type high explosive is cast, in each mold, in the presence of primary initiator support means therefor.

In one embodiment, the process of the invention is carried out by introducing a molten high explosive such as Composition B, Pentolite, TNT, Amatol, and the like, into a plurality of separate and upwardly extending open end molds, integrally joined at their open ends in substantially the same plane to form a tray type assembly of integral construction, generally containing in the order of from 6 to 50 molds per tray. Each individual mold contains supported therein, a well member, and/or one or more tubes extending therethrough for tunnel formation; and, alone, or together with any such well and tube structure above described, an opening in a side,

or bottom wall, for support of a detonating fuse emplaced in the molten mass during casting and extending from within the booster charge through the wall, to an external point for communication with the energy source. The molten masses of explosive are then solidified by cooling, and the resulting tray assembly of booster type initiators of the invention is ready for storage and associated handling prior to need for the individual booster type initiators at the shooting site.

It is sometimes advantageous that an insert of additional explosive be placed in the open end mold during the casting process so as to be embedded in the cast explosive in detonating relationship therewith and with the primary initiator means, supported in any suitable manner. The insert explosive, often PETN, is of a sensitivity greater than that of the cast explosive and serves to facilitate detonation of the cast explosive in response to initiation of the primary initiator. The insert, generally a closed tube containing the more sensitive explosive, is disposed in the mold in any suitable manner so as to be in the above described detonating relationships.

The individual booster type initiators each of which comprises the cast charge and the mold in which it was formed are supported as units of the integral tray assembly along any suitable lines of detachable support extending in the assembly intermediate the open ends of all adjacent mold members. Each booster unit can then be neatly torn from the tray unit along the particular lines as needed.

Although it is generally preferred to detachably support the individual molds of the assembly along lines of perforations as described above, the individual molds can be so detachably disposed in any suitable manner, as for example along lines of sulficiently thin gauge construction material, that the molds can be readily detached along those defined lines merely by tearing or cutting. The lines of detachable support can be emplaced before or subsequent to the casting as desired.

Further in accordance with the invention, a molding assembly for the manufacture of cast booster type initiators is provided which comprises a plurality of open end mold members adjacently disposed and joined as members of a molding assembly of integral construction; and means for detachably supporting each said mold, as an element of said integral molding assembly, along lines in said assembly extending intermediate the open ends of adjacent mold members. Generally, each said mold member also contains primary initiator support means for a booster type high explosive, i.e. for support of a primary initiator in detonating relationship with cast booster explosive when formed in the mold.

In preferred practice, the molding assembly of the invention is a tray type unit of integral construction which comprises a plurality of adjacently disposed open end molds extending codirectionally and integrally joined at their open ends in substantially the same plane, as separate elements of an integral tray type unit together with primary initiator support means, and detachable support means, as described.

The preferred tray type molding assembly contains an opening in one of the sides of each open end mold to accept passage of a detonating fuse from within the mold to an external point, to thereby function as support for a detonating fuse as a primary initiator for the cast explosive charge when contained within the mold. The opening in the mold sidewall is preferably in a side opposite the open end of the mold. The open ends of all molds in the tray type assembly, as they terminate in substantially the same plane, are joined by an interconnecting wall to complete formation of the integral unit. A continuous line of perforations is disposed within the interconnecting wall member between the open end of each mold and all molds adjacent thereto. The perforations are of any suitable size and frequency to secure a path along which the individual mold can be readily torn from the tray. The tray type mold assembly can be formed from any suitable material. Such materials now preferred are suitable cellulose ethers and cellulose esters, high impact polyethylene, polystyrene, polypropylene and the like, all of which can be readily associated with the cast booster charge as a fuel.

Although the above described lines of detachable support for the open end molds of the integral molding assembly are preferably perforated, they can be of any suitable form. For example, each line of detachable support can be a continuous indentation of relatively thin gauge plastic, i.e. thinner gauge than that from which the remainder of the assembly is formed to thereby facilitate detaching of the individual booster type initiator assemblies by cutting or tearing along the defined lines.

Although preferably the open end tray members are supported at their open ends terminating in substantially the same plane and are joined by an interconnected wall in which the line of detachable supports is preferably disposed, the tray members can be joined at other points if desired, as for example in a plane containing the bottom ends thereof by an interconnecting wall similarly containing a line for detachable support of the mold members.

When the particular molding material is a plastic such as cellulose ethers, or esters, polyethylene, polypropylene, polystyrene and the like, the molds are of a wall thickness generally in a range of from 5/1000 to 50/1000 inch. Although the tray molding assembly is generally an integral unit of about 6 to 50 mold members, the number of molds generally utilized is dependent upon the degree of convenience in handling in any given set of circumstances.

Although it is not required that the mold members contain primary initiator support means, each open end mold, in preferred practice, contains an opening in a wall portion thereof as support for a detonating fuse, as a primary initiator, as above described, or alternatively any suitable primary initiator support means, For example, in other embodiments a tube, closed at one end, as a well member for a primary initiator, extends, closed end first, into the open end mold through a wall thereof, and is supported at its open end in the mold wall member; and/or one or more open end tubes can extend through the open end mold, supported in a wall of the mold, for the formation of a tunnel(s) for accepting a detonating fuse(s) as a primary initiator for the cast charge. Often, formation of one or two tunnels is preferred alone or with a well member, although a well member can be present as the only support means for a primary initiator, when desired.

Further, in accordance with the invention is provided a tray type molding assembly, above described, in combination with a plurality of cast booster type high explosive charges formed therein. In one embodiment, the said combination comprises a cast high explosive, preferably Pentolite, Composition B, TNT or Amatol, within cach of the open end molds, often in an amount of from about 30 to 2500 grams. Each mold member contains an opening in a wall, preferably opposite the open end of the mold, and a detonating fuse extends from within the cast explosive in the mold to the outside of the mold through the opening. In another embodiment, each cast charge of the combination contains a tube, closed at one end, extending through a wall of the mold, closed end first, into the cast charge as a cap well therefor, alone or together with at least one tunnel extending through a wall of the mold and on through the cast charge. However, the tunnel structure can also be present independently of the well structure. In other embodiments an insert, above described, is also present within the cast charge in detonating relationship with the primary initiator and the cast charge as a supplemental charge.

The above described plurality of booster type charges as an integrally supported unit is particularly advantageous inasmuch as it is formed in a single casting step and is then ready for convenient storage and shipping to the shooting site, without need for processing of any kind; and it serves to dispense each booster initiator from the integral unit, individually as needed, without requirement at any time for the separation of the cast booster charge from the individual mold in which it was formed. This aspect of the invention provides, further, for conveniently shaped assemblies for efficient stacking and hence shipping and handling prior to use, and for selection of suitable charges for desired direction effects and initiation efficiency.

The invention is illustrated with reference to the drawings, all of which are perspective views, and of which FIGURE 1 illustrates a tray type molding assembly of the invention in which each mold member contains an opening in a bottom end, or wall, portion for support of a detonating fuse as a primary initiator, and wherein each mold is detachably supported in the integral tray assembly unit along a line of perforations; FIGURES 2A and 2B are views of tray type molding assemblies of the invention illustrated with reference to FIGURE 1 but containing alternatively shaped molds; FIGURE 3 illus trates a now preferred form of detonating fuse structure as a primary initiator to be supported in an integral tray assembly of the invention during casting of the booster explosive charge; FIGURE 4 illustrates a tray molding assembly of the invention with reference to FIGURE 1, containing a plurality of integrally supported cast booster charges for storage, shipping, and handling prior to use in firing; FIGURE 5 illustrates a booster type initiator assembly of the invention detached from an asssembly of booster initiators of FIGURE 4; FIGURES 6A6C illustrates tray type molding assembly structure of FIG- URE 1 except that the mold members contain various suitable welland/or tunnelforming members for support of primary initiator means in the explosive charge when cast therein; FIGURE 6D illustrates a tray type molding assembly of the invention, with reference to FIGURES 6A-6C, additionally containing explosive charge cast therein together, and optionally, with an insert" of supplemental charge; and FIGURES 7A and 7B illustrate molding assembly and integrally supported booster charges therein, as booster type initiators of the invention, with reference to FIGURES 6A6D but of alternatively shaped molds and optionally containing insert" structure the same as that of FIGURE 6D except in combination with other well and/or tunnel structure.

Referring to FIGURE 1, molds are each frustoconical with open end 11 at the base of the cone and extend codirectionally and are integrally joined at open ends 11 in substantially the same plane by interconnecting sheet member 16 to form integral tray type assembly 12. A continuous line of perforations 13 in interconnecting sheet member 16 around the entire open end 11 of each mold 10 is intermediate each mold 10 and all molds 10 adjacent thereto to detachably support each mold 10 as a unit of integral tray assembly 12, i.e. to provide a line along which each mold 10 can be individually detached from the remainder of the integral assembly 12. Each mold member 10 contains an opening 9 in the bottom, of closed, end 8 thereof as support for a detonating fuse extending from within mold 10 to an outside point, as a primary initiator for an explosive charge when the latter is contained within the mold member.

As illustrated with reference to FIGURES 2A and 2B, in which primed numbers refer to corresponding (though not exactly like) parts of structure of FIGURE 1 identified by the same but unprimed numbers, molds 10 of FIGURE 1 can, in accordance with other embodiments, be of any suitable shape which often determines the particuluar interconnecting structure for integral support of the molds in the tray unit.

Thus, as shown in FIGURE 2A, molds 10' can be trapezoidal, and each contains a flange, or wall, member 17 extending laterally entirely about its open end 11'. Adjacent molds 10 are connected along the opposing interfaces of their flanges 17 to form a resulting interconnecting wall member 16' which is integral with all molds 10' about their open ends 11', as support for molds 10 in an integral tray assembly 12'. A continuous line of perforations 13', is disposed in the interconnecting member 16', intermediate all adjacent molds 10' to thereby detachably support molds 10 as units of tray assembly 12'. Further, as shown in FIGURE 28, the molds 10" can be cup shape, the open end 11" of each being connected with that of an adjacent mold 10 by an interconnecting sheet 16 and being detachably supported in the resulting tray assembly in substantially the same manner as shown with reference to molds 10 and sheet member 16 of FIGURE 1 to form a tray assembly 12" of integral construction.

Referring to FIGURE 3 is shown a detonating fuse system 18 now preferred as a primary initiator for a booster type initiator of the invention. The detonating fuse system 18 is disclosed and claimed in my copending application Ser. No. 674,278 filed concurrently herewith. Thus, separate detonating fuse strands 19a and 19b in detonating fuse system 18 extend in parallel in close proximity to, and generally, in direct contact with the other as a double strand along the pattern of a U-shape loop to form a resulting detonating fuse element 21. The core loading of the U-shape fuse element 21 is at least and generally in the order of about 50 to 300 grains PETN (or equivalent) per foot. A separate detonating fuse 22, as a tail fuse for the detonating fuse system 18 extends in contact with fuse element 21 from within the U loop through the open end thereof to an external point. The core loading of detonating fuse 22 is not above about 40 and is often in the order of from about 5 to 35 grains PETN (or equivalent) per foot. Detonating fuse 22 is supported in the loop of fuse element 21 in direct contact with one or both of strands 19a and 1% by any suitable means such as by a metal tie 23 disposed around a section of fuse element 21 through which fuse 22 extends.

Tie member 23 can be a tab ring member, cord, or the like, although a metal tie is preferred inasmuch as it also contributes additional detonating energy that results from the formation of molten metal particles and impact of same with the booster charge at the time of initiation.

When desired, detonating element 21 can be formed from a single detonating fuse strand (not shown). In that event, the core loading for the single strand of the loop is obviously greater than that of each of the individual strands 19a and 19b in order that the single strand fuse element provide the same detonating energy as the double strand element 21, when both loops are of the same length.

The detonating fuse system of FIGURE 3 is particularly preferred because it provides a higher than normal core loading in the initiation area Without incurring appreciable loss in compactness of the booster assembly while at the same time providing increased flexibility of the tail portion extending to the energy source.

Referring to FIGURE 4, in which the lettered index numbers refer to like parts identified in FIGURES 1 and 3 by the same, but unlettered, numbers is shown a tray type molding assembly 12a containing a cast booster type explosive charge 24 in each of the molds 10a as product of the casting process of the invention. In each mold 10a is inserted a fuse system 180, with fuse element 21a dis posed within each mold 101: and tail fuse 22a extending through the opening 9a in end member 8a opposite the open end 1111. Each tail fuse 22a extends from the mold 10a to a suitable energy source for firing. Molten high explosive 24, often Pentolite, is poured into each mold 10a to immerse the detonating fuse element 21a therein, and the resulting mass of molten explosive, containing the detonating fuse supported in opening 911, is then solidified by cooling to form solid cast booster charge 24 containing detonation fuse system 18a as shown.

The resulting tray assembly 12a integrally supports the plurality of individual booster charges and in turn comprises an integral unit of a plurality of booster type initiators of the invention, each of which includes the cast booster charge 24, the mold a in which it was formed, together with primary initiator support means therefor-and in this embodiment, the primary initiator also. It eliminates need for removal of the booster from the mold at any time, even for firing. Indeed, it is an important feature of the invention that each individual mold 10a and its total content can be simply detached from the remaining integral unit by tearing along the appropriate perforations 13a and the detached unit emplaced, as a booster initiator of the invention, in the main explosive charge for detonation.

Referring to FIGURE 5 in which the primed index numbers refer to like parts identified by unprimed index numbers of FIGURE 4, is shown a now preferred booster type initiator of the invention, detached from the integral unit of booster type initiators of FIGURE 4. Thus, booster type initiator of the invention comprises mold 10a detached from the integrally supported assembly 12a of FIGURE 4 and containing charge 24 together with detonator fuse system 21a therein and tail fuse 22a extending therefrom. The frustoconical shape of booster type initiators 10a is particularly preferred because it provides for increased initiation efiiciency for a given weight of booster charge, which depends on the diameter of the base of the cone.

By way of example, a tray assembly 12a of FIGURE 4 is formed by injection molding high density polystyrene or polyethylene into an integral unit of individual. molds 10a of about 0.030 inch wall thickness. A detonating fuse system 18 of FIGURE 3, emplaced in each mold 10a, as illustrated with reference to FIGURE 4, is formed from a U-shape loop 21a of double strand Primacord 2 inches in length and having a core load of from 50 to 200 grains PETN (or equivalent), the loop being one inch in length, and a tail fuse 18a of core loading in order of 25 grains per foot, and about 18 inches in length. 300 grams of molten Pentolite is then poured into each mold 100 and the resulting molten mass, containing the detonating fuse system supported in the mold is permitted to solidify by cooling. The resulting filled tray constitutes an integrally supported plurality of cast booster type charges, and a plurality of booster type initiators of the invention as an integral unit ready for storage, shipment and associated handling; and the individual booster initiators, each including the explosive charge and the mold 10a in which it was cast, are ready for detachment from the tray assembly for use as needed at the blasting site.

With reference to each of FIGURES 6A-6C in which all lettered index numbers refer to like parts of FIGURE 1. identified therein by the same, but unlettered, index numbers, is illustrated a tray type molding assembly 12b containing mold members 10b with lines 13b of perforations above the open ends for detachably supporting the molds as described with reference to lines 13 of FIG- URE l. The integral tray type mold assembly 12b, shown in each of FIGURES 6A-6C, differs from assembly 12 of FIGURE 1 only in respect of support structure therein for primary initiator means for a booster type explosive charge when cast in molds 10b.

Thus, in FIGURE 6A each mold 10b contains open end tubular support stub 26 extending into mold 101) through bottom end 8 thereof, and terminating in close proximity to the inner side of bottom end 8. Closed end tube 28 extends within mold 10b and is frictionally supported at its open end in stub 26, as a cap well member for explosive charge to be cast in mold 1015, being thereby in communication at its open end with the outside of mold 10b. Alternatively, tube member 28 can be open at both ends and extend entirely through each mold 10b as a 8 form for tunnel formation in the explosive charge cast in each of the molds 101:.

Similarly, as illustrated with reference to FIGURE 68, in which all primed index numbers refer to like parts of FIGURE 6A identified therein by the same but un' primed numbers, mold member 1011 can contain a well member 28' supported in a stub 26' as illustrated with reference to FIGURE 6A and an open end tube member 31 extending through mold 10b and supported at one end in stub 32, generally by friction, being in open communication at its open ends with the outside of each mold 10b. Alternatively, in lieu of well member 28, and stub member 26', mold 10b can contain respectively an additional open end tube member 31 supported in an additional stub support 32, thereby providing for two separate tunnels in the explosive cast in the mold for support of a fuse type primary initiator.

As shown in FIGURE 6C, in which all primed numbers refer to like parts of FIGURES 6A and 6B identified by the same but unprimed, or less primed, numbers, each mold 10b can contain two open tubes 31, each supported in a support stub 32' as illustrated with reference to tube member 31 and stub member 32 of FIGURE 6B, and a well member 28" supported in a support stub 26" all as illustrated with reference to FIGURES 6A and 6B.

FIGURE 6D illustrates a plurality of primary initiator assemblies of the invention as an integral unit 12b, each of which includes a mold 10b of FIGURES 6A-6C, a booster type explosive charge 24" cast therein, such as explosive charge 24 of FIGURE 4 and primary initiator support means of FIGURES 6A-6C, with specific reference to that of FIGURE 6Cready for detachment from the integral unit 12 and firing. Optionally included in each cast charge 24" is an insert" 29 of supplemental high explosive charge supported in an upright position in a triangle formed by the two tunnel forming tubes 31" and well member 28".

With reference to FIGURES 7A and 7B are shown booster type initiators of the invention detachable from an integrally supported plurality such as of FIGURE 6D except that the

mold members

10a and 10"a are those of FIGURES 2A and 2B respectively and contain primary initiator support means of FIGURES 6A-C, specifically illustrated with reference to FIGURES 6B and 6A, respectively. Thus, in FIGURE 7A, index numbers 26"a, 28"a, 31'a, and 32'a refer respectively to like

parts

26', 28', 31 and 32 respectively of FIGURE 6B; and mold 10'a contains cast booster type high explosive charge 24'a and, optionally, an insert 29a of high explosive of sensitivity greater than that of booster charge 24'a and supported horizontally in the cast explosive intermediate the two tubes 28"a and 31'a so as to be in detonating relationship with cast charge 24'a and a primary initiator when supported in members 28"a and 31'a. In FIGURE 7B, index numbers 26'a and 28a refer respectively to like

parts

26 and 28 of FIGURE 6A and mold 10"a contains cast booster type high explosive charge 24"a and, optionally, an insert 29"a, the same as insert 29'a of FIGURE 7A, in cast charge 24"a and disposed in detonating relationship with both charge 24"a and primary initiator means when supported in member 28a.

The tray type assemblies of the invention are advantageously formed by injection molding a plastic suitable for that purpose, preferably polyethylene. Generally, however, when fabricating the molding assembly containing tube members for formation of tunnel and/or well elements, the tube members are added to the otherwise finished assembly by insertion in each mold with support in a suitable support stub, as illustrated, the stub being advantageously integral with each mold member, and hence a part of each mold formed by injection molding.

When referring herein to a mass of explosive charge for casting, in practice of the invention, it is meant any booster type high explosive that can be placed in a mold, in liquid and flowable form, take the shape of the mold, and thereafter solidify to a rigid solid state. In preferred practice, the explosive to be cast is liquified by heat to thereby become molten and is then caused to solidify in the mold by cooling. Exemplary molten masses for casting, in preferred practice of the invention, are Pentolite, a suspension of PETN in molten TNT, generally in about 50/50 weight proportions; Composition B, a suspension of RDX in molten TNT generally in about 60/40 weight proportions; Amatol, a suspension of ammonium nitrate in molten TNT also in about 50/50 weight proportions; and TNT.

Other liquid masses of booster type explosive can be cast in practice of the invention although they do not necessarily require heat to become liquid but solidify in the mold. Exemplary of this latter class of materials are suspensions of one or more of RDX, PETN, tetryl and the like in a suitable liquid epoxy type plastic which is caused to solidify in the mold by curing in the presence of a suitable catalyst, in accordance with such catalytic reactions well known in the plastics art.

Although the process, molding assembly, and booster type initiator of the invention do not require specific primary initiator support means in the mold, such is generally preferred. When specific primary initiator support means is not contained in the mold, a detonating fuse as a primary initiator can be emplaced within the liquid explosive during casting, so as to extend from within the cast explosive through the open end of the mold to a point outside the mold for communication with the energy source. However, it is not required that a detonating fuse, or other suitable primary initiator, be inserted in the liquid explosive during casting when there is no primary initiator support means Within the mold. Thus, when the explosive is cast without primary initiator support means in the mold, primary initiator support means can be secured, in any suitable manner, to the individual booster initiator after it is detached from the mold assembly for use, as for example by tying a detonating fuse, to, or around, the detached booster type initiator, or by tying an electric blasting cap thereto.

As will be evident to those skilled in the art, various modifications can be made or followed, in the light of the foregoing disclosure and discussion, without departing from the spirit or scope of the disclosure or from the scope of the claims.

What I claim and desire to protect by Letters Patent is:

1. A process for the manufacture of booster type initiators for explosives, which comprises casting a mass of a booster type high explosive in each of a plurality of separate molds integrally joined as a unit of one-piece construction; and detachably supporting each resulting individual mold and cast product contained therein, in said one-piece construction along a line of structural weakness extending in said unit intermediate said individual mold and the entire remainder of said unit.

2. In a process of claim 1, casting each said mass of explosive when initially in molter form and in the presence of primary initiator support means therefor.

3. In a process of claim 2, casting from 30 to 2500 grams of an explosive, in each said mold, selected from the group consisting of Pentolite, Composition B, Amatol and TNT.

4. An assembly of booster type initiators for explosives, which comprises a plurality of codirectionally extending and adjacently disposed open end molds integrally joined in a one-piece construction to form a resulting integral molding unit; a cast booster type high explosive cast in each said mold; and said integral unit containing a line of structural weakness intermediate each said mold and the entire remainder of said unit as means for detachably supporting each said mold as an element of said one-piece construction.

5. An initiator assembly of claim 4 wherein the open ends of said molds are in substantially the same plane,

and said molds are integrally joined at their open ends, by an interconnecting wall, as separate elements of an integral tray type molding unit; means within each said mold for support of primary initiator means for said cast explosive therein; and each said line for detachable support being a continuous line of perforations in said interconnecting wall.

6. In an initiator assembly of claim 5, at least one tube member extending entirely through said cast explosive in and through at least one wall member of, each said mold in open communication at both ends with the outside of said mold; and not more than one tube, closed at one end, extending closed end first through a wall of, and into said cast explosive in, each said mold in open communication at its open end with the outside of said mold.

7. In an initiator assembly of claim 5, a tube, closed at one end, extending closed end first into said cast explosive in each said mold through a wall thereof in open communication at its open end with the outside of said mold.

8. In an initiator assembly of claim 4, a detonating fuse extending from within each said cast explosive through the open end of said mold containing same.

9. In an initiator assembly of claim 4, each said mold containing an opening in a wall thereof, and a detonating fuse extending from within each said cast explosive through said opening to the outside of said mold.

10. In an initiator assembly of claim 9, a detonating fuse system Within each mass of said cast explosive, said detonating fuse system comprising (1) a detonating fuse element, as a U-shape loop, having a core loading of at least 50 grains PETN (or equivalent) per foot and (2) a separate fuse extending as a tail member in contact with said fuse element from within said loop along the length of said loop and through the open end thereof, and having a core loading not exceeding 40 grains PETN (or equivalent) per foot; and said tail member extending from within said cast explosive through said opening to a point external to said mold.

11. In an initiator assembly of claim 6, an insert of a high explosive, of sensitivity greater than that of said cast explosive, in each said mold in direct contact with said cast explosive therein and spaced from said tubes to detonate in response to initiation of primary initiator means when supported in said tubes.

12. In an initiator assembly of claim 7, an insert of a high explosive, of sensitivity greater than that of said cast explosive, in each of said molds in direct contact with said cast explosive therein and spaced from said tube, to detonate in response to initiation of primary initiator means when supported in said tube.

13. An individual booster type initiator comprising a mold containing a cast booster type high explosive cast therein, and detached from a molding unit initially containing same; said molding unit comprising (1) a plural ity of codirectionally extending and adjacently disposed open end molds joined in a one-piece construction to form a resulting integral molding unit, and (2) a line of structural weakness contained in said integral unit intermediate each said mold and the entire remainder of said integral unit as means for detachably supporting each said mold, as an element of said one-piece construction, and said booster type initiator being detached from said integral unit along a line of said detachable support intermediate same and the remainder of said unit.

14. A detached booster type initiator of claim 13 wherein each mold in said integral molding unit contains an opening in a wall thereof, and a detonating fuse extending from within said cast explosive in each said mold, through said opening, to the outside of said mold; Wherein said molds are integrally joined at their open ends in substantially the same plane by an interconnecting wall member to form a resulting integral tray type molding unit; and wherein each said line of detachable support is a continuous line of perforations in said interconnecting wall member.

15. A detached booster type initiator of claim 13 wherein, in said integral molding unit, at least one tube member extends through at least one wall of each said mold and through said cast explosive therein in open comrnunication at both ends with the outside of said mold; wherein not more than one tube closed at one end, extends closed end first through a wall of each said mold into said cast explosive therein in open communication at its open end with the outside of said mold; wherein said molds are integrally joined at their open ends in substantially the same plane by an interconnecting wall member to form an integral tray type molding unit; and wherein each said line of detachable support is a continuous line 1 of perforations in said interconnecting wall member.

16. A detached booster type initiator of claim 13 wherein each mold of said integral molding unit contains a tube, closed at one end, extending closed end first into each mold through a wall thereof in open communication at its open end with the outside of said mold.

17. A detached booster type initiator of claim 15 containing an insert of high explosive therein of sensitivity greater than that of said cast charge, in direct contact with said cast explosive and spaced from all of said tubes to detonate in response to initiation of primary initiator means when supported in said tubes.

18. A detached booster type initiator of claim 16 containing an insert of high explosive of sensitivity greater than that of said cast explosive in direct contact with said cast explosive and spaced from said tube to detonate in response to initiation of primary initiator means when supported in said tube.

References Cited UNITED STATES PATENTS 3,037,453 6/1962 Cook et al. 10224 3,349,710 10/1967 Sposimo 102-865 3,359,902 12/1967 Minnick et al 10224 FOREIGN PATENTS 599,612 6/1960 Canada. 599,614 6/1960 Canada. 663,864 5/1963 Canada.

VERLIN R. PENDEGRASS, Primary Examiner.

US. Cl. X.R. 861