US3136052A

US3136052A - Process for the closure of hollow bodies

Info

Publication number: US3136052A
Application number: US814714A
Authority: US
Inventors: Pickart Auguste Jean- Ghislain
Original assignee: FN Herstal SA
Current assignee: FN Herstal SA
Priority date: 1958-06-04
Filing date: 1959-05-21
Publication date: 1964-06-09
Anticipated expiration: 1981-06-09
Also published as: GB897673A; FR1223086A; BE568340A; NL239701A; ES250046A1; NL106032C

Description

J1me 1964 A. JEAN-BAPTISTE GHISLAIN PICKART 3,136,052

PROCESS FOR THE CLOSURE OF HOLLOW BODIES Filed May 21, 1959 United States Patent 3,136,052 PROfIESS FOR TIE CLOSURE OF HOLLOW BODIES Auguste Jean-Baptiste Gliislain Pickart, Seraing, Belgium, assiguor to Fabrique Nationale dArmes de Guerre, Societe Anonyme, Herstal-lez-Liege, Belgium Filed May 21, 1959, Ser. No. 814,714 Claims priority, application Belgium June 4, 1958 2 Claims. (Cl. 29-543) It is known to effect the closure of cartridge cases for sporting firearms in various manners and particularly by providing folds at the end thereof and turning the folds down towards the centre.

In a conventional process of this nature, the foldingdown is effected until the inner folds project below the plane of the closure, i.e. are inscribed within an extremely obtuse cone towards the interior of the case. In another process, the folds form projecting ribs externally of the plane of closure, inscribed in a truncated cone towards the exterior of the case.

Since therefore the known processes of closure by folding do not permit the obtaining of a closure other than a plane or frusto-conical closure, they are not suitable for the manufacture of practice cartridges suitable for use in all kinds of automatic firearms without any form of adaptation other than the addition at the end of the barrel of a device the purpose of which it is to limit the gas-flow section. In fact, the closure obtained by these known processes results in the formation of an excessively large plane surface or of a series of sharp ridges distributed over an excessively large diameter which become caught at one or the other point during the travel of the cartridge before it is received in the barrel chamber, the result being failure in the feed. If it is to function correctly in all cases, the cartridge should terminate in a portion the shape of which is as similar as possible to that of the real projectile and which guides the cartridge over the path from the magazine to the barrel chamber and its centre of gravity should be conveniently situated in such manner that at the moment of ejection it carries out the same movements as those of the case of a real cartridge.

Hitherto, during practice, use has been made of ammu nition called blank ammunition wherein the projectile is a dummy and consists for example of a piece of wood having the shape of the real projectile and being inserted in the case. Although ammunition of this kind is similar to real ammunition, it has disadvantages during firing practice in which the adversaries may fire point-blank since, in this case, the dummy bullet is fired like a projectile and may cause accidents.

Practice cartridges are also known wherein the body of the'case of plastic material is prolonged by a portion in the form of a dummy projectile which is also of plastic material. The behaviour of these cartridges, the dummy projectile of which remains integral with the case, differs from that of real cartridges, in view of the difference in the nature of the materials; since the specific weights, coefiicients of expansion, softening temperatures and mechanical rigidities are different, these cartridges are not entirely satisfactory.

The present invention relates to a process for the closure of hollow cylindrical bodies of slight thickness and consists in forming on the end of the body a small number of folds, in rounding the ridges of the external folds whilst simultaneously bending them down towards the longitudinal axis, and in simultaneously elongating them transversely so as to constitute an ogive (conical point).

According to a feature of the invention, there are initially produced, in a first phase, internal folds which are brought into contact and which have substantially the shape of arcs of a circle; the second phase consists in flattening the ridges of the external folds whilst folding them down towards the axis and elongating them transversely by means of a concave ogival matrix exerting a longitudinal thrust towards the body, so that each initial external fold yields two lateral folds.

An especially advantageous embodiment consists of practice ammunition wherein the case is prolonged by an inseparable terminal portion corresponding to the projectile and having its free end closed by the present process; the said cylindrical terminal portion is directly manufactured with the body of the case and is fitted thereon and secured thereto by welding during the manufacturing process.

Further features will be apparent from the following description of the accompanying drawings which refer to an embodiment of a practice cartridge.

In the said drawings:

FIGURE 1 is a view, partially in perspective and drawn to a large scale, of the end of a practice cartridge to be closed, shown after the first phase of operation;

FIGURE 2 is a lateral view, drawn to a large scale and in elevation, of the final ogive obtained, and FIG- URE 3 is a sectional view taken along the line IIIIII of FIGURE 2;

FIGURE 4 is a diagrammatic view, drawn to a still larger scale, and showing in plan the end of the ogive and the deformation of the folds for forming the ogive;

FIGURE 5 is an elevational view of a completed practice cartridge.

Referring to FIGURE 1, it will be seen that the body 1 of the case is prolonged by a tubular and cylindrical terminal portion 2, the said portion 2 comes, together with the body 1, directly from the factory in the case of small-bore ammunition. If the ammunition is of large size, the body of the case and the terminal tubular portion may be manufactured separately, the said terminal tubular portion then being made integral with the case by Welding.

Applied on the circular end of the element 2 is a matrix the interior of which is provided with three pins arranged at under the pressure exerted by the matrix, the end is deformed and is formed with three inner folds 3, arranged at 120 relatively to one another, and with three outer folds 4 arranged also at 120, as apparent from FIGURES 1 and 4. It should be noted that the inner folds 3 have the form of arcs of a circle brought into contact with each other.

In the following phase, the end thus folded is covered with a matrix of ogival shape, exerting an axial thrust towards the body of the case.

By this action, the inner folds 3 substantially retain their shape; at the beginning of this phase, the initial external folds 4 are flattened so as to adopt the position 4' shown in broken lines, whilst being turned down towards the axis 5, as shown in FIGURE 4. The initial folds 4 are then crushed (flattened) and laterally extended so as to form the final lateral folds such as those shown at 4a and the lips 4b and 4c of which are pressed together; at the point 6 of the ogive, the outer lips 4b constitute a more or less complete circular surface (FIGURE 4) since the lateral folds 4a are in contact with each other at that point. The further away from the point 6, the greater will be the spacing between the folds 4a, as apparent from FIGURES 2 and 3.

The completed ammunition will have the appearance shown in FIGURE 5.

The process just described permits the obtaining of a practically continuous annular closure surface; the interstices of communication towards the interior are almost completely closed and the radius of the closureogive may be varied in accordance with necessity.

indented sufficiently to cause the internal folds to con- In the case of practice ammunition, the terminalportion representing the dummy projectile is no longer separated from the case; it is not projected and cannot result in accident during point-blank firing; furthermore, the shape and mechanical characteristics of the cartridge resemble those of a real cartridge as closely as possible.

The description given hereinabove and the drawings relate to a mode of closure wherein three folds are used. This number of folds is not limitative since, where required, use may be made of a larger number of folds;

Calculation shows, however, that there is little advantage in increasing the number 'of folds with a view to reducing the diameter of the terminal portion. The utilisation of three folds constitutes furthermore a special feature of this mode of closure.

Since the powder charge of a practice cartridge manufactured in accordance with the present process is diminished, it is necessary to maintain it in place near the percussion cap by using an adequate tamping means.

tact one another at the end of the body around the longitudinal axis of said body, and deforming the external folds by pressing said external folds inwardly in a radial; direction while simultaneously crushing and rounding the folds circumferentially into arcuate segments substantially of double thicknesscooperatively contacting one another to define a substantially circular externalsurface,

said crushing androunding of the external folds being" varied lengthwise. of the body to cause the arcuate segments to contact oneanother at the end of the body and to be spaced from'one another in. increasing mannerin a direction away from the end of the body'to form a closedogival end on said body.

2. A process as claimed in claim 1 wherein thereis'h formed three external and three internal 'folds whereby The said tamping means consists of nitrated paper or of some other substance the combustion of which is practically instantaneous, so as to avoid any projection of solid fragment out of the barre1, since such projection could entail a certain element of danger.

What I claim is:

1. A method for closing the end'of a hollow cylin drical body comprising indenting the body radially inwardly at the end thereof at angularly spaced locations to form arcuate internal folds alternating with external" folds along the periphery of the body, the body being adjacent internal folds includean angle therebetween of 7 R eferenc eslCitedin the file of this patent UNITED. STATES PATENTS Salisbury June 127,- 1386

Claims

1. A METHOD FOR CLOSING THE END OF A HOLLOW CYLINDRICAL BODY COMPRISING INDENTING THE BODY RADIALLY INWARDLY AT THE END THEREOF AT ANGULARLY SPACED LOCATIONS TO FORM ARCUATE INTERNAL FOLDS ALTERNATING WITH EXTERNAL FOLDS ALONG THE PERIPHERY OF THE BODY, THE BODY BEING INDENTED SUFFICIENTLY TO CAUSE THE INTERNAL FOLDS TO CONTACT ONE ANOTHER AT THE END OF THE BODY AROUND THE LONGITUDINAL AXIS OF SAID BODY, AND DEFORMING THE EXTERNAL FOLDS BY PRESSING SAID EXTERNAL FOLDS INWARDLY IN A RADIAL DIRECTION WHILE SIMULANEOUSLY CRUSHING AND ROUNDING THE FOLDS CIRCUMFERENTIALLY INTO ARCUATE SEGMENTS SUBSTANTIALLY OF DOUBLE THICKNESS COOPERATIVELY CONTACTING ONE ANOTHER TO DEFINE A SUBSTANTIALLY CIRCULAR EXTERNAL SURFACE, SAID CRUSHING AND ROUNDING OF THE EXTERNAL FOLDS BEING VARIED LENGTHWISE OF THE BODY TO CAUSE THE ARCUATE SEGMENTS TO CONTACT ONE ANOTHER AT THE END OF THE BODY AND TO BE SPACED FROM ONE ANOTHER IN INCREASING MANNER IN A DIRECTION AWAY FROM THE END OF THE BODY TO FORM A CLOSED OGIVAL END ON SAID BODY.