Anti-strain device for artillery projectiles

Description

[0001] The present invention relates to an anti-strain device for the tubular shell of artillery projectiles intended to eject a useful load.

[0002] It is known that when an artillery projectile is fired, a translation movement and a spin around its axis are simultaneously imparted to it by the pressure exerted by the combustion gases of a propellant explosive, which pressure is transmitted through the base plug applied on the tubular shell of said projectile.

[0003] Said base plug must be separable from the projectile when its purpose is to carry on a predetermined target a useful load, for example an illuminating or smoke producing canister, or a set of small bombs; this useful load being ejected from the projectile at the time of splitting up and caused to fall to ground.

[0004] The maximum operating pressure due to the combustion gases of the explosive causes permanent distorsions in the tubular shell of the projectile, which distorsions, if their amount is higher than allowable, can damage the inner canister or prevent its correct ejection. This leads to defective operation or even to disastrous breakage.

[0005] Generally the more heavily stressed areas are found to be those under the driving band, where the equivalent stresses reach their maximum values. If that area is free to warp, considerable wall displacements can take place, such as to lead even to scraping off of the driving band itself, especially for projectiles with a tubular shell of small thickness.

[0006] DE-A-2 100 276 discloses a reinforcement device substantially made of a ring inserted in the shell at the portion to be reinforced.

[0007] It is the object of the present invention to provide an improved anti-strain device for the portion of the tubular shell between the driving band and the base plug of the projectile.

[0008] This object is achieved by a device as described in claim 1.

[0009] It is obvious that the metal reinforcing structure according to the invention can have several embodiments, depending particularly on the kind of useful load contained in the tubular shell of the projectile.

[0010] By using the reinforcement device according to the invention, the strains of the tubular shell are limited to allowable values, so as to avoid the inconveniences of the prior art.

[0011] The invention will be better understood from the following description, given merely as an example and therefore in no limiting sense, of three embodiments thereof, referring to the accompanying drawings in which:

Fig. 1 is a partial longitudinal sectional view of the end portion of an artillery projectile of a type intended to carry a useful load which, in this specific case, consists of sub-ammunition, a first embodiment of the invention being shown in the figure;

Fig. 2 is a plan view of the metal reinforcing structure alone, as shown in Figure 1;

Fig. 3 is a vertical cross-sectional view of it, taken along line 3-3 of Figure 2;

Fig. 4 is a sectional view similar to that of Figure 1, showing a second embodiment of the invention, for the case in which the useful load is for example an illuminating canister with its associated parachute;

Fig. 5 is also a sectional view similar to that of Figure 1, showing a third embodiment of the invention for the case in which the useful load consists for example of pyrotechnical mixtures.

[0012] Referring to Fig. 1 it can be seen that between the driving band 1 of an artillery projectile intended to carry a sub-ammunition load 2, and its base plug 3 there is arranged in contact with the inner wall of the tubular shell 4 a metal reinforcement structure 5 for said tubular shell 4. Said reinforcement structure 5 is better seen in Fig. 2 and 3, where it is shown alone. It should be noted that in Fig. 1 the reinforcement structure 5 is sectioned along a line 1 - 1 indicated in Fig. 2.

[0013] As is apparent from the figures, the first embodiment shown of the reinforcement structure according to the present invention is particularly suited to the case in which the useful load consists of sub-ammunition 2, in which case a lightweight but particularly strong reinforcement structure 5 is provided which in addition does not take precious space from the useful load.

[0014] Fig. 2 shows a locating key 6 which can be engaged in a corresponding seat provided on the inner wall of the tubular shell of the projectile to prevent angular displacements of the structure 5 with respect to the projectile during its firing. In the embodiment illustrated said key 6 is fixed to the structure 5 by means of two screws 7.

[0015] As can be seen in Fig. 2, the reinforcement structure of said first embodiment has a central circular hole and six holes regularly arranged radially around the central hole, all holes having the same diameter.

[0016] Of course, the diameter of the holes, as well as their number and arrangement depend on the dimensions of the sub-ammunition 2 which represents the useful load of the projectile.

[0017] A second embodiment of the invention is shown in Fig. 4, in which the metal reinforcement structure consists of a ring formed by a stub pipe 5' within which for example the parachute 2' of an illuminating canister is arranged. In this case the reinforcement structure has been designed so as to leave free the whole space inside the ring 5'. The thickness of the ring 5' should be determined in dependance on the type of material, its construction and the stresses which it shall have to withstand without excessive strain of the tubular shell 4.

[0018] Fig. 5 shows a third embodiment of the metal reinforcement structure according to the invention. In this embodiment the metal reinforcement structure 5" is shaped like an annular box and it also acts as a container, for example for a pyrotechnical mixture. Of course, the wall thickness of the box 5" is to be designed independence on loads and allowable strains.

[0019] In all three embodiments described the outer diameter of the reinforcement structure can be made slightly smaller than the inner diameter of the tubular shell of the projectile. The clearance so obtained will facilitate an introduction of the reinforcement structure into the tubular shell 4, but it should nevertheless be such as not to allow an excessive strain of the tubular shell 4 during firing.

Claims

1. Reinforcement device for a portion of the tubular shell (4) of an artillery projectile of the kind intended to carry a useful load, said portion of the tubular shell (4) being comprised between the driving band (1) and the base plug (3) of the projectile, comprising a metal structure (5) having a cylindrical side surface, with an outer diameter substantially equal to the inner diameter of the portion of the tubular shell (4) to be reinforced, characterized in that said metal structure (5) is substantially cylindrical and is provided with a plurality of circular through holes parallel to the longitudinal axis of said structure.

2. Reinforcement device as claimed in claim 1, characterized in that one of said holes of said metal structure (5) is central and the other holes are disposed radially around said central hole.

Ansprüche

1. Verstärkungsvorrichtung für einen Teil des rohrförmigen Mantels (4) eines Artilleriegeschosses von der Art. welche zum Tragen einer Nutzlast vorgesehen ist, wobei der genannte Teil des rohrförmigen Mantels (4) zwischen dem Führungsband (1) und dem Endpfropfen (3) des Geschosses liegt, bestehend aus einer Metallkonstruktion (5) mit einer zylindrischen Seitenfläche, mit einem Außendurchmesser, der im wesentlichen gleich dem Innendurchmesser des zu verstärkenden Teiles des rohrförmigen Mantels (4) ist, dadurch gekennzeichnet, daß die Metallkonstruktion (5) im wesentlichen zylindrisch ist und mit einer Vielzahl von runden, parallel zur, Längsachse der Konstruktion verlaufenden Löchern versehen ist.

2. Verstärkungsvorrichtung nach Anspruch 1, dadurch gekennzeichnet, daß eines der Löcher der Metallkonstruktion (5) zentral ist und die anderen Löcher radial um das zentrale Loch herum angeordnet sind.

Revendications

1. Dispositif de renfort pour une partie d'une coquille tubulaire (4) d'un projectile d'artillerie du type destiné à porter une charge utile, ladite portion de coquille tubulaire (4) étant comprise entre la ceinture de propulsion (1) et le culot (3) du projectile, comportant une structure métallique (5) ayant une face latérale cylindrique à diamètre extérieur substantiellement égal au diamètre intérieur de la portion de coquille tubulaire (4) à renforcer, caractérisé en ce que ladite structure métallique (5) est substantiellement cylindrique et en ce qu'elle est pourvue d'une pluralité de trous circulaires traversants orientés parallèlement à l'axe longitudinal de ladite structure.

2. Dispositif de renfort selon la revendication 1, caractérisé en ce que l'un desdits trous dans ladite structure métallique (5) est central, tandis que les autres trous sont disposés radialement autour dudit trou central.

Drawing