GB2164131A

GB2164131A - Process for the production of a grenade body

Info

Publication number: GB2164131A
Application number: GB08521025A
Authority: GB
Inventors: Hans Assmann
Original assignee: Oregon Etablissements fuer Patentverwertung
Current assignee: Oregon Etablissements fuer Patentverwertung
Priority date: 1984-08-28
Filing date: 1985-08-22
Publication date: 1986-03-12
Also published as: ES8702645A1; EG16918A; DE3528609A1; GB8521025D0; ES546435A0; MY101326A; GB2164131B; SG63888G

Abstract

In the production of a grenade body, the fragmentation casing 1 is but up in a step-wise manner by producing a receiving portion 15 which has a large opening (5), through which the explosive filling (2) is then introduced, and completing the fragmentation casing by means of a completing portion 8 whilst leaving a fuse tube opening (3). A plastics sheathing 7 may already be applied to the receiving portion 15 if the latter represents a substantial part of the fragmentation casing 1 and the completing portion (8) represents a closure plug for the opening (5). However, the plastics sheathing 7 may also be injected moulded around the fragmentation casing, as a final step, the fragmentation casing forming a heat- insulating cover for the explosive (2). In this alternative form of the process, the receiving portion 15 and the completing portion 8 are substantially identical half shell members which are fitted around a preformed explosive filling (2). <IMAGE>

Description

SPECIFICATION Process for the production of a grenade body This invention relates to a process for the production of a grenade body, in particular a hand grenade body, have an explosive-filled fragmentation casing comprising fragments which are embedded in plastics material, and an opening for introducing a fuse tube of a fuse which can preferably be fixed to a plastics sheath preferably enclosing the fragmentation casing.

Particularly in relation to hand grenades, it is conventional practice to produce a fragmentation casing which is closed except for the filling opening for the explosive, through which the fuse or detonator tube is then fitted, the fragmentation casing possibly also comprising two members which are to be joined together, and preferably being covered with an external layer comprising thermoplastic material. The filling opening may not be of less than a given cross-section which depends on the properties of the explosive material to be introduced.

Hitherto, the filling opening was generally provided at the location where the opening for the fuse tube, which opening is smaller in itself, is required, so that at least the remaining part of the fragmentation casing can be of a closed construction. A hand grenade of that kind is disclosed for example in Austrian patent specification No 357 904. Austrian patent specification No 348 898 also discloses a hand grenade which has a removable, nonsheated fragmentation casing so that the explosive which is disposed in a containiner can be used alone as an attack hand grenade and, with a fragmentation casing, as a defense hand grenade.

A process for the production ol a fragmentation casing with an opening at top and bottom is disclosed in DE-OS No 23 44 173, wherein a double-case hollow member is filled with a hardenable plastics-fragment mix.

There is thus a need for a generally improved process for the production of a grenade body, in particular a hand grenade body, of the kind set forth in the opening part of this specification, wherein the fragmentation casing is completely closed with the exception of the fuse tube opening which corresponds to the diameter of the fuse tube, and in which the operation of-introducing any explosive does not give rise to any difficulties.

According to the present invention there is provided a process for the production of a grenade body, in particular a hand grenade body having an explosive-filled fragmentation casing comprising fragments which are embedded in -plastics material, and an opening for introducing a fuse tube of a fuse which can preferably be fixed to a plastics sheath preferably enclosing the fragmentation casing, in which firstly a receiving portion of the plastics-encased fragmentation casing is produced, which receiving portion has an opening through which explosive can be introduced into said receiving portion, then explosive is introduced, and finally the fragmentation casing is completed by completing or closing the receiving portion, except for a fuse tube opening.

The process according to the invention therefore makes it possible to provide an opening of any desired size for introducing the explosive into the body, while nonetheless producing the closed fragmentation casing.

The process according to the invention also makes it possible to use any suitable explosive for increasing the effectiveness of the grenade, which hitherto encountered difficulties in regard to handling and manufacture due to the endeavour to provide a filling opening of minimum size in order to render the fragmentation effect more uniform, while finally the process of the invention provides a fragmentation casing which, in test explosions, gave substantially the same fragmentation effect and density in all directions.

A smooth seam and contact surface between the receiving portion and the completing portion of the fragmentation casing can result in disturbances in the fragmentation pattern, that is to say, irregularities in the way in which the fragments are dispersed. In this respect, some problems can be overcome in a simple manner if the receiving portion is formed with uneven portions in the seam or contact surface with the completing portion of the fragmentation casing, whereby fragments are also arranged in the regions of the seam or contact surfaces.

The irregularities or uneven portions of the seam or contact surfaces between the individual portions of the fragmentation casing may be formed for example by steps or by a tongue and groove configuration. In that connection, it is advantageous if the notional extension of the surface regions disposed transversely with respect to the outside surface of the fragmentation casing represents a geometrical surface which intersects a plurality of fragments in one of the two portions to be joined together.As generally substantially spherical fragments are disposed in virtually closely packed form in the portions of the fragmentation casing, the surface regions of the irregularities or uneven portions, which extend transversely with respect to the outside surface of the fragmentation casing, are preferably displaced relative to each other by a distance which approximately corresponds to the radius of the spherical fragments or an odd multiple of the radius.

Another embodiment provides that a tooth configuration may be formed between the receiving portion and the completing portion, wherein the irregularities or uneven portions thereof are preferably formed by parts of the fragments projecting from the two seam or contact surfaces.

In relation to the two portions of the fragmentation casing, the fuse or detonator tube opening which usually extends along the longitudinal axis of the grenade body can be selected to be disposed at any desired position which derives from the shaping of the individual portions of the fragmentation casing. In regard to production however it is advantageous if at least a part of the fuse tube opening is formed in the completing portion of the casing. In that connection, a preferred construction wherein the receiving portion is of a container-like form with a cavity therewithin provides that after the introduction of the explosive, to form a closure plug, plastics material with embedded fragments is poured into the opening for introducing the explosive, as the completing or closure portion of the fragmentation casing.In this case also the fuse tube opening may be provided in the completing or closure portion of the casing so that the latter represents a kind of closure sleeve for the opening for introducing the explosive. As a higher number of fragments is desirable in the region of the fuse tube opening to adapt that region, in regard to fragmentation effectiveness, to the remainder of the fragmentation casing, such a closure sleeve extends slightly into the internal cavity or also outwardly, preferably with a projection portion.

After the plastics material which has been cast in position and which bears the missing fragments has set, it completes the receiving portion to make up a fragmentation sleeve which is completely closed off, by virtue of engagement thereof into the irregularities or uneven portions or the formation of the tooth configuration.

In particular hand grenades generally have a sheathing of thermoplastic material. In this connection, in a first embodiment, the receiving portion may be provided with the plastics sheating before the casing is filled with explosive and, after the completing portion or closure plug has hardened, a cover portion comprising the material of the sheathing is applied to the closure plug.

Instead of casting the completing portion in position, it is also possible to complete the receiving portion by means of a preformed completing portion which is inserted into the opening for introducing the explosive, for example in the form of the closure plug, preferably being secured in position by adhesive, in which connection the irregularities or uneven portions which are preferably provided, depending on the respective nature of their configuration, may also produce a positive connection between the components.

Another alternative form of the process according to the invention provides that two identical half shell members are produced as the receiving portion and the completing portion, wherein a respective half of the fuse tube opening is provided at each of the contact surfaces, and a preformed insert of solid explosive is fitted into the receiving portion, then the completing portion is fitted into position and finally the completed fragmentation casing containing the explosive is fitted into the mould cavity of a casting mould, in particular an injection casting mould, in which the plastics sheathing is formed thereon.

It is surprising in particular in relation to that process that the high temperatures produced in the cavity of the injection moulding tool for forming the outer sheathing on the grenade (the injection moulding tools are heated and the liquid plastics material is injected at temperatures of about 200 to 250"C) do not have any disadvantageous effect on the explosive which is also introduced into the casing, although the temperatures obtaining at the walls of the mould and in the mould cavity for the external sheathing may be of the order of magnitude of the melting point or the firing temperature of cast or pressed explosives.

However, the danger of firing of the explosive does not occur (the risk of detonation does not arise in any case because a detonator is required for that purpose). That is achieved by virtue of the fragmentation casing being closed except for the fuse tube opening and which serves as thermal insulation for the explosive. It has been found that, under the short-term effect of a temperature of from 200 to 250"C on the fragmentation casing, temperatures for example around 70"C occur, which are far below the melting temperature or firing temperature of the solid explosive.

The invention will now be described in greater detail, by way of example, to the accompanying drawings, in which: Figure 1 is a view in longitudinal section through a hand grenade body produced by the process according to the invention, Figures 2 to 4 show individual steps of the production process, and Figure 5 shows a step in an alternative form of production process according to the present invention.

A hand grenade body as shown in Fig. 1 comprises a fragmentation casing 1 with fragments 10 which are embedded in a hardened plastics material. The casing is completely closed, except for an opening 4. The fragmentation casing is filled with explosive 2 and a fuse tube 3 of a fuse projects through the opening 4 into the explosive 2. The fragmentation casing 1 is further provided with a sheathing 7, preferably comprising thermoplastic material, which has a neck portion 14 for fixing the fuse. As the cross-section of the opening 4 only corresponds to the diameter of the fuse tube 3, it is not possible for the explosive 2 to be introduced through the opening 4. Therefore, the fragmentation casing 1 is made up from two portions.In this operation, firstly a receiving portion 15 of the fragmentation casing 1 is produced, having an opening 5 for introducing the explosive, then the explosive 2 is introduced, and finally the fragmentation casing 1 is finished off by means of a closure or completing portion 8.

Fig. 1 shows a first construction in which the completing portion 8 forms a closure sleeve for the receiving portion 15 of the fragmentation casing 1, which portion 15 is provided with a sheathing 7 and is filled with explosive 2 through the opening 5 for introducing the explosive. The mode of operation which is used in that respect will be described in greater detail with reference to Figs. 2 to 4. In that connection, in producing the fragmentation casing 1, the seam or join surface 16 of the opening 5 for introducing the explosive is provided with irregularities or uneven portions 6 which are formed for example by a stepped configuration and by parts 13 of the fragments 10, which project out of the receiving portion 15 (see Fig. 2).After the explosive 2 has been introduced (see Fig. 3), a hardenable plastics 11, for example a casting resin, which corresponds to the material used for the fragmentation casing 1, is poured into the opening 5 and then (see Fig. 4) the number of fragments 10 required for arming the closure sleeve which is to be formed as the completing portion 8 are pressed in around the mandrel 9. It will be appreciated that it is also possible to introduce a plastics-fragment mix which has previously been prepared. In that operation, as can be seen from Fig. 4, the fragments 10 penetrate between the projecting parts 13 of the fragments 10 of the receiving portion 15, thereby forming a tooth or serration configuration in respect of the completing portion 8 with the receiving portion 15, and the entire fragmentation casing 1 is substantially uniformly and completely closed off.After the material has hardened, instead of the large opening 5 for introducing the explosive, the grenade has the substantially smaller fuse tube opening 4 whose diameter corresponds to that of the fuse tube 3, and through which it would have been impossible to introduce the explosive 2. In order to give a more uniform fragmentation pattern, the closure sleeve is provided with a greater number of fragments 10 which are embedded on both sides in extension portions 12 of the sleeve, of which the outer one extends into the neck portion 14 of the sheathing 7 on to which the fuse head with the fuse tube 3 is screwed.

Fig. 5 shows a second alternative embodiment. In accordance therewith, firstly the explosive 2 is preformed in the form of a body corresponding to the cavity in the fragmentation casing 1, and a centrai bore is left free to receive the fuse or detonator tube 3. The preformed explosive body is for example a pressing consisting of Hexastit or Pentastit. In addition, two half shell members are produced to act as the receiving portion 15 of the fragmentation casing 1 and as the completing or supplementing portion 8 thereof. The explosive 2 is fitted into the receiving portion 15, the open side of which forms the opening 5 for introducing the explosive, and the completing portion 8 is fitted into position. In that case, the joint or contact surfaces 16 of the two shell-like portions 8 and 15 of the fragmentation casing 1 are secured together by adhesive.In addition, as illustrated, the surfaces 16 may be of a stepped configuration in cross-section or may have a groove-and-tongue cross-sectional configuration. Each portion 8 and 15 is provided at one side with a central opening 4' at its edge, with the openings 4' supplementing each other to make up the fuse tube opening 4.

In the next step in the process, the assembled fragmentation casing 1 together with the explosive 2 in the interior thereof is put into the mould cavity of an injection moulding tool where a thermoplastic material such as polyethylene, in a hot and liquid condition, is moulded on to the outside surface of the fragmentation body, thereby forming the external sheathing 7. It will be appreciated that in this case also a tube-like projection 12 may be provided at least in an outward direction, in the region of the opening 4 for the fuse tube.

The process as described above with reference to two embodiments provides a grenade body having a fragmentation casing which is filled with explosive and which is of an outwardly swelling configuration, being for example of ball-like or egg-like shape, together with an external sheathing of plastics material which is preferably in one piece. The crosssection of the opening 4 for receiving the fuse tube 3 is substantially less than the maximum cross-section of the explosive 2 which is introduced into the grenade, preferably being a quarter thereof. Therefore, the fragmentation casing 1 almost completely encases the explosive 2 (except for the small opening for the fuse tube). That has a particularly advantageous effect in regard to distribution of the fragments in a uniform pattern around the grenade upon detonation thereof.

Claims

1. A process for the production of a grenade body, in particular a hand grenade body having an explosive-filled fragmentation casing comprising fragments which are embedded in plastics material, and an opening for introducing a fuse tube of a fuse which can preferably be fixed to a plastics sheath preferably enclosing the fragmentation casing, in which firstly a receiving portion of the plastics-encased fragmentation casing is produced, which receiving portion has an opening through which explosive can be introduced into said receiving por tion, then explosive is introduced, and finally the fragmentation casing is completed by completing or closing the receiving portion, except for a fuse tube opening.

2. A process according to claim 1, in which the receiving portion is formed with uneven portions in the seam or contact surface with a completing or closure portion of the fragmentation casing.

3. A process according to claim 2, in which between the receiving portion and the completing or closure portion is formed a tooth configuration which comprises at least partially mutually overlapping fragments of the receiving portion and the completing or closure portion.

4. A process according to claim 2 or claim 3, in which at least a part of the fuse tube opening is formed in the completing or closure portion.

5. A process according to any one of claims 1 to 4, wherein the receiving portion is of a container-like configuration having a cavity therewithin, in which after the introduction of the explosive, to form a closure plug, plastics material with embedded fragments is poured into the opening for introducing the explosive, as the completing portion of the fragmentation casing.

6. A process according to claim 5, in which the receiving portion is provided with a plastics sheathing prior to introducing the explosive, and, after the closure plug has hardened, a cover means comprising the material of the plastics sheathing is applied to the closure plug.

7. A process according to any one of claims 1 to 4, in which the receiving portion is completed by means of a preformed completing or closure portion.

8. A process according to claim 7, in which two identical half shell members are produced as the receiving portion and as the completing portion, wherein provided at the contact surfaces is a respective half of the fuse tube opening, a preformed insert of solid explosive is fitted into the receiving portion, then the completing portion is fitted into position, and finally the completed fragmentation casing containing the explosive is fitted into a mould cavity of a casting mould, in particular an injection moulding mould, in which a plastics sheathing is formed on the completed fragmentation casing.

9. A process for the production of a grenade body, substantially as hereinbefore described with reference to Figs. 1 to 4 or Fig.

5 of the accompanying drawings.

10. A grenade body produced according to the process of any one of claims 1 to 9.