TUBULAR SHELL FOR ARTILLERY PROJECTILES WITH INTERNAL UNDERCUT AND FILLING SECTORS

Abstract: A tubular shell for artillery projectiles, which can be used as a carrier for an internal canister, or load, of an illuminating or smoke producing or deflagrating type, the ejection from the projectile and the operation of which are activated by known pyrotechnic and mechanical devices. In order to make possible to reduce the thickness and weight of the tubular shell to the minimum value compatible with the stresses due both to starting accelerations of the projectile and to internal pressures generated by a suitable splitting-up charge, the tubular shell (1) of the projectile according to the present invention is made of a single part instead of being divided in two or more parts as in the prior art, and it is internally undercut by means of flask boring machining, so as to provide an internal shoulder (4) at the end of the internal undercut facing the end plug and an internal shoulder (5) at the end facing the nose. The internal undercut is filled by a cylindrical insert (2) of a material which is lighter than that of the tubular shell (1) and the introduction and fitting of which into the tubular shell (1) is made possible in that the insert (2) is subdivided by longitudinal cuts into sectors (2a, b, c, d) which are embedded and fixed between said internal shoulder (4, 5).

Description: Tubular shell for artillery projectiles with internal undercut and filling sectors. The present ; invention relates to a tubular shell for artillery projectiles which can be used in particular as a carrier of an internal canister, or load, of an illuminating or smoke producing or deflagrating type, the ejection from the projectile and the operation of which are activated by suitable known pyrotechnic and mechanical devices. According to the prior art, to the purpose of providing in a tubular shell body of a given external profile for a projectile of the above type having the desired bal- listic properties a weight reduction and at the same time keeping unaffected the masses toward the larger diameters, in favour of an increase of stability of the whole system, an undercutting is made by boring machin¬ ing of the internal surface of said tubular shell, which to this purpose has to be composed of two or three parts, with resulting cost and time waste, and by inserting tubes of a lighter material, suitably shaped, into the undercuts. The purpose of these tubes is to keep to a cylindrical shape the internal chamber, so as to pro- vide a continuous guide to the internal load, or cani- ster, of the projectile during the ejection movement. The tubes themselves are also intended to keep or ad¬ just the weights of the assembly to within expected to¬ lerances. This projectile structure according to the prior art has the inconvenience of being expensive and work consuming, because of the plurality of pieces to be machined and of their corresponding coupling surfaces, whose degree of finish has necessarily to be very accurate; and in spite of this accuracy of machining, in every case the subdivision of the tubular shell into more parts repre¬ sents an intrinsic weakening which does not allow a priori to reach optimum compromise conditions between light weight and mechanical strength. The purpose of this invention is to eliminate the above inconveniences of the prior art by providing a tubular body for artillery projectiles of the abovementioned known type which is provided with the desired ballistic properties, which has an internal volume optimized to suit the contents for which it is intended, minimum stresses and strains and minimum weight with respect to those provided by the present state of the art, and ^ which in . ad&iti . on . is inexpensive to manufacture. This purpose as well as others stated below are reached according to the present invention by providing a tubu¬ lar shell for artillery projectiles of the type pre- viously mentioned which consists of an internally hol ¬ low body of high mechanical strength comprising a nose- shaped front zone provided with threaded connection for the fuse of an approximately cylindrical central part, and of a tapered rear zone, provided with base plug, said body being undercut in its internal part and said undercut being filled up to the required diameter with a material having a specific weight lower than that of the tubular shell, characterized in that the tubular shell body is made of a single part, that the internal undercut is performed by boring machining to a flask shape of the internal surface of the tubular shell, so as to provide an internal shoulder at the end of the internal undercut facing the end plug and a shoulder at the end of the internal undercut facing the nose-shaped zone, and that the filling material consists of a cy¬ lindrical insert having at least one longitudinal cut along at least one generating line of.ife,to allow it ' s intro duction into the hollow part of the cylindrical shell body made of a single part, from the opening of the cy¬ lindrical body facing the base plug,and to make possible to fit the insert itself in contact with the internal wall of the undercut and against the internal shoulders of the hollow part, after overtaking the internal shoulder. Conveniently, the cylindrical insert is longitudinally subdivided in a number of cylinder sectors, permanently and firmly fixed to the internal surface of the under¬ cut so as to prevent a relative movement of the insert itself with respect to the tubular shell. It is also convenient that the fixing of the insert against the internal surface of the undercut be effect¬ ed by means of glueing or riveting, or by means of stud bolts, and that the material of the insert be composed of a light alloy, or a plastic material, or a composite material. The invention will be better understood from the follow- ing description, given merely as an example and there¬ fore in no limiting sense, of an embodiment thereof, referring to the accompanying drawings, in which: Pigure 1 represents a partly sectional longitudinal view of a tubular shell for artillery projectiles according to the present invention; and Pigure 2 represents an enlarged cross-sectional view, taken along line II-II of Pigure 1, of the tubular shell according to the present invention. Referring first to Pigure 1, it can be seen that the tu¬ bular shell according to the present invention consists of a body 1 of a single piece, internally hollow, of high-resistance-steel, with a nose-shaped front outside provided with a threaded connection 8 for the nose, with a central cylindrical part providing a guide during mo¬ tion in the barrel, and with a tapered back portion pro¬ vided with a base plug 3. To the tubular shell a driving band is connected, which is known to the expert of the art and does not require any further explanation. Approximately in correspondence of the central cylindri¬ cal part of the tubular shell 1 an undercut 9 is obtained by means of flask boring machining of the internal sur¬ face, so as to provide an internal shoulder 4- at the end of the internal undercut facing the end plug 3, and a shoulder 5 at the end of the internal undercut facing the nose-shaped zone. The internal undercut is filled with a number of sectors 2, which in the embodiment shown are four in quantity, as can be seen in Pigure 2 which is described below. These sectors can be manufactured from various types of materials, having a specific weight lower than that of the material of the tubular shell 1. It has been found to be particularly suitable, according to the particular application of the projectile, to manufacture these sec¬ tors from light alloy, or plastic material, or composite material. The sectors are introduced into the cavity of the tubu¬ lar shell through the opening 6 of the base plug and are •restrained between shoulders 4 and 5 which are foreseen to this purpose. Instead of an insert made of a number of sectors, a cy¬ lindrical insert of flexible material longitudinally cut along a generating line can be adopted, in which case the introduction into the cavity of the tubular body through the aperture β can be effected by overlapping the facing edges of the longitudinal cut and then spreadingthem out again in their seat against the surface 9 after overtak¬ ing the shoulder 6. Into the body 1, which is open in its back portion through which the load is inserted or ejected, a base plug 3 is inserted and it is suitably fixed to it, for example by forcing or threading (not shown). Pigure 2 shows the tubular shell of the invention in a cross-section through the cylindrical intermediate por¬ tion. The number 1 indicates the tubular steel shell body, while numbers 2a , b , c , d indicate the four filling sectors. The number of the se sectors as well as their shape can be varied according to the particular design requirements. The filling sectors 2 are.resting, from the base plug end, against the shoulder 4, whose area should be such as not to allow to exceed during firing the maximum allowable specific pressures of the constituent ma- terial ' of the sectors themselves. In addition, it is convenient that these sectors be further secured against the wall 9 with suitable means such as by glueing and/or riveting, or by means of screws or other means or combination of means per se known. In this way the locking action provided by the shoulders 4 and 5 between which the sectors are re¬ strained can be completed. Thanks to the use of the ar¬ rangements provided according to the present invention, a weight reduction of the tubular shell body of the projectile, an increase of its strength thanks to the elimination of joints, and a cost reduction in terms of machining times and material can be contemporarily realized.

Claims: Claims 1. A tubular shell for artillery projectiles consisting of an internally hollow body (1) with high mechanical strength comprising a nose-shaped front zone provided with threaded connection (8) for the fuse of an approxi- mately cylindrical central part and of a tapered rear zone, provided with base plug (3), said body being un¬ dercut in its internal part (9) and said undercut being filled up to the required diameter with a material hav¬ ing a specific weight lower than that of the tubular shell, characterized in that the tubular shell body (1) is made of a single part, that the internal undercut is performed by boring machining to a flask shape of the internal surface of the tubular shell, so as to pro¬ vide an internal shoulder (4) at the end of the internal undercut facing. he end plug (3) and a shoulder (5) at the end of the internal undercut facing the nose-shaped zone, and that the filling material (2) consists of a cylindrical insert (2) having at least one longitudinal cut along at least one generating line of it, o..allow its introduction into the hollow part of the cylindrical shell body (1) made of a single part, from the opening (6) of the cylindrical body facing the base plug and to make possible to fit the insert itself in contact with the internal wall of the undercut (9) and against the internal shoulders (4,5) of the hollow part (2), after overtaking the internal shoulder (4). 2. A tubular shell for artillery projectiles as claimed in claim 1, characterized in that the cylindrical insert (2) is provided with four longitudinal cuts which subdi¬ vide the insert itself into four cylinder sectors ( 2a, b , c , d ) . 3. A tubular shell as claimed in claim 1 or 2, characte¬ rized in that the cylindrical insert (2) is permanently and firmly fixed to the internal surface of the undercut (9) SD as to prevent a relative movement of the insert (2) itself with respect to the tubular shell (1). 4. A tubular shell as claimed in claim 3, characterized in that the insert (2) is fixed to the internal surface of the undercut (9) by glueing. 5. A tubular shell as claimed in claim 3, characterized in that the insert (2) is fixed to the internal surface of the undercut (9) by means of riveting. β. A tubular shell as claimed in claim 3, characterized in that the insert (2) is fixed to the inside surface of the undercut (9) by means of stud bolts. 7. A tubular shell as claimed in claim 1 or 2, characte¬ rized in that the cylindrical insert (2) is freely fitted in the undercut (9). 8. A tubular shell as claimed in one of claims 1 to 7, characterized in that the insert (2) is of a light alloy. 9. A tubular shell as claimed in one of the claims 1 - 7, characterized in that the insert (2) is of plastic material. 10. A tubular shell as claimed in one of claims 1 - 7, characterized in that the insert (2) is of a composite material.

Inventors: ANDREETTA RODOLFO, ANDREETTA, RODOLFO
Applicants: SIMMEL SPA, SIMMEL S.P.A.
Application year: 1985
Main classification: F42B13
IPC codes: B23P11, B23P15, F42B12, F42B30