A FRAGMENTATION BOMB

Abstract: A fragmentation projectile such as a single or dual purpose grenade (4) or bomblet for a cargo projectile comprising a fragmentation body (8) enveloping an explosive charge (17) carrying casing (5), which fragmentation body comprises one or more fragmentation rings (9) having a plurality of axially oriented notches (2), said notched rings (9) being confined between unnotched first and second terminal members (10, 11). Where the grenade is dual purpose, anti-personnel and anti-­ armour, the explosive charge (17) inside the casing (5) is sealed off by a conical liner (18).

Description: The present invention relates to anti-personnel and anti-armour munition such as bombs, grenades and explosive projectiles. One particular category of such munition is that classified as cargo munition, in which a cargo projectile is utilized to carry and deliver a plurality of grenades, e.g. dual purpose grenades or bomblets serving for anti-personnel and anti-armour purposes. Known grenades of this type comprise a cylindrical body made from a hardened, heat-treated steel. This construction is dictated by the stresses to which the grenade is subject during firing of the cargo projectile and the release and ejection of the grenades therefrom. The invention relates, inter alia, to grenades for cargo projectiles as disclosed in European Patent application number 0 176 885. In the following description and claims the term "fragmentation grenade" will be used to describe the type of munition with which the invention is concerned, it being understood that such munition is not restricted to grenades proper and comprises also other types of munitions such as bombs, single and dual purpose grenades or bomblets for cargo projectiles, explosive projectiles and the like. The design of any fragmentation grenade must allow for fragmentation of the body so as to disperse numerous fragments which will maximize the anti-personnel effect in the target area. The fragmentation efficiency of grenades of conventional construction is limited, partially because the above-referred to design criteria which call for a construction which can withstand the firing and ejection stresses, and this is incompatible with design criteria calling for good fragmentation properties. This is true even if the grenade body is pre-stamped with a fragmentation pattern. It is known that explosive forces released within cylindrical vessels subject the walls to stresses according to principles which dicate that the radial stress is twice that of the longitudinal stress. Therefore the longitudinal fragmentation of such cylindrical bodies, i.e. the tearing open of the body in an axial direction, will not normally occur simultaneously with the radial fragmentation. Thus the fragmentation efficiency and the resulting distribution of fragments is unsatisfactory. The problem underlying the present invention is to provide a new and improved fragmentation grenade of a design such that the above-referred to disadvantages are significantly reduced or overcome and which design will provide effective shattering upon impact are significantly reduced or overcome. A fragmentation grenade which overcomes this problem is defined in the appendant claim. All fragmentation rings are preferably equiradial. The axial notching of the fragmentation rings may be on the inside or outside edges thereof. If the fragmentation grenade is single purpose the explosive charge inside the casing is sealed off by an end plate. If the fragmentation grenade is dual purpose, anti-personnel and anti-armour, said charge of explosive material inside the casing, being designed as a shaped charge, is sealed off by a concial liner which tapers in a direction away from said first end of the casing. A fragmentation means including equiradial fragmentation rings, stacks of fragmentation rings, a plurality of axially oriented notches (inside, outside or both of fragmentation envolopes), as well as a shaped charge of explosive are well known in the art (French patent specification 1 275 604, disclosing a warhead, US patent specification 2,798,431 and French patent of addition specification 996 disclosing a warhead which incorporates non-shaped charges and notched fragmentation envelopes, and European patent application publication number 0 176 885 disclosing a shaped-charge/fragmentation bomblet). Brief Description of the Drawings For better understanding the invention will now be described with reference to the attached drawings, in which: Fig. 1 is a plan view, partly in section, of a pre-notched fragmentation ring used for making a fragmentation grenade in accordance with the invention; Fig. 2 is an elevation of the ring of Fig. 1; Fig. 3 is an axial section of a dual purpose fragmentation grenade according to the invention. Description of a Specific Embodiment Referring now to Figs. 1 and 2, there is shown a metal ring 1 which has a plurality of notches 2 along its inside edge 3. The pre-notching of the ring in the axial direction creates a stress weakness such that radially directed forces cause an extremely high radial fragmentation efficiency. The dual purpose, anti-personnel and anti-armour fragmentation grenade 4 according to the present invention shown in Fig. 3 comprises a longitudinal casing 5 having a first, open end 6 and a second, closed end 7. Casing 5 is enveloped by a fragmentation body 8 comprising a plurality of notched fragmentation rings 9 and the kind shown in Figs. 1 and 2, which rings are equiradial and stacked one on top of the other. Rings 9 are confined between first and second unnotched members 10 and 11, the first unnotched member 10 being annular and seated near the first end 6 of casing 5 on an outer circumferential shoulder 12 thereof while the second unnotched member 11 is cap-shaped and seated near the second end 7 of casing 5 on a fluted portion 13 thereof. The second unnotched member 11 of fragmentation body 8 is tightly secured to casing 5 by a tubular locking rivet 14 engaging registering bores in member 11 and casing 5 and having a fluted skirt 15 and an annular head 16. The substantially cylindrical casing 5 contains a charge of explosive material 17 sealed off by a conical metal liner 18 forming a tapering interior wall and leaving a cavity 19. A substantially cylindrical end portion 20 of the conical interior liner 18 has an integrally formed circumferential outer rib 21 which mates with an annular groove 22 near the first end of casing 5 whereby liner 18 is retained in position. The explosive charge 17 and liner 18 are thus designed as a shaped charge assembly which, as known per se, produces upon detonation an armour piercing jet in axial direction. In an alternative embodiment of the invention the explosive charge 17 may fill out substantially the entire inner space of casing 5 and be sealed off by a substantially circular, flat end plate suitably received at the first end of the casing. For detonation of the explosive charge 17 there is provided a booster charge 23 located in an axial bore of the tubular rivet 13. The booster charge 23 is of a kind known per se and may be in form of an assembly comprising retaining plates and a tightly packed explosive charge. In operation booster charge 23 is detonated by a conventional striker pin/primer mechanism forming part of the grenade head assembly (not shown) mounted on top of member 11 and rivet 14. Assembly of the fragmentation grenade 4 shown in Fig. 3 may proceed by first connecting casing 5 whose open, first end portion is yet unshaped, to member 11 by means of rivet 14. Thereafter fragmentation rings 9 are mounted on casing 5 and this is followed by mounting the base ring 10. Once the base ring 10 is mounted the end portion of casing 5 is shaped by rolling so as to form the circumferential groove 21 and the fluted portion thereof the match the internal shoulder 12 of member 10. After completion of the rolling operation, the booster charge assembly 23 is inserted into the central cavity of rivet 14 and this can be achieved either by using a ready-made booster charge assembly or by assembling it in situ. The central cavity of rivet 14 msy be provided with means (not shown) such as a shoulder, for holding the booster charge assembly 23 in position. At this point, the fragmentation grenade is inverted and explosive charge 17 is poured into casing 5. The conical interior liner 18 is then inserted and a pressure operation is performed on the substantially cylindrical end portion 20 of liner 18 to integrally form a circumferential outer rib 21 which locks it into the annular groove 22 of casing 5. From the foregoing description it is readily understood that the fragmentation grenade according to the invention excels by a high, reliable and reproducable fragmentation efficiency in both radial and axial directions. The radial fragmentation is facilitated by the notched design of each of the fragmentation rings that constitute the grenade body; and where two or more such rings are provided axial fragmentation is pre-determined and requires very little energy by the very fact that the grenade body is constituted by a plurality of discrete rings. Although particular embodiments of the invention have been described and illustrated herein, it is recognized that modifications and variations may readily occur to those skilled in the art and consequently, it is intended that the claims be interpreted to cover such modifications and equivalents. In particular it should be noted that instead of using fragmentation rings that are notched on the inside edge, it is also possible in accordance with the invention to use rings that are notched on the outside edge or even on both sides.

Claims: A dual purpose, anti-personnel and anti-armour fragmentation grenade being of the cargo munition type and comprising fragmentation means and a shaped charge of explosive material (17) enclosed within a substantially cylindrical casing (5) having a first, open end (6) and a second, mainly closed end (7), a fragmentation ring being mounted on the outer side of said substantial cylindrical casing, characterized in that the fragmentation means comprises at least two equiradial rings (9) each fragmentation ring has a plurality of axially oriented notches (2) on the inside edge; the fragmentation rings are confined between unnotched first and second terminal members (10, 11) to form therewith a fragmentation body (8), said first terminal member (10) being annular and located near said first, open end (6) of the casing in a manner that prevents disengagement in a direction away from said second end of the casing, said second terminal member (11) being located near the second end (7) of said casing; means (14) are provided for locking together said terminal member and casing; said second terminal member (11) being linked to the second end (7) of the casing by a tubular rivet (14) engaging registering bores of the terminal member (7) and casing (5), and said rivet (14) accommondates a booster charge (23).

Inventors: EYAL, JOSEPH, ROSENBERG, AVRAHAM, ZALMON, SEEV, WILLY
Applicants: ISRAEL MILITARY INDUSTRIES LTD.
Application year: 1987
Main classification: F42B12
IPC codes: F42B12