US2965034A - Shell cases - Google Patents

Description

L. HEIDMANN Dec. 20, 1960 SHELL CASES 5 Sheets-Sheet 1 Filed Feb. l2. 1957 MOLD WALL |Iv w L.HEIDMANN Dec. 20, 1960 SHELL CASES 3 Sheets-Sheet 2 Filed Feb. l2, 1957 3 Sheets-Sheet 3 United States Patent O SHELL CASES Leon Heidmann, Paris, France, assignor to Forges et Ateliers de Constructions Electriques de Jeumont, Paris, France, a corporation of France Filed Feb. 12, 1957, Ser. No. 639,673

Claims priority, application France Mar. 4, 1952 l6 Claims. (Cl. 102-43) This invention relates to shell cases and other containers of like shape of the type described in my co-pending applications No. 292,321, filed June 7, 1952, now abandoned, and No. 491,943, led March 3, 1955, now abandoned, of which this application is a continuation-inpart.

The invention consists of improvements in shell cases or containers having a multi-layer wound tube or tubular body portion and to an improved and novel method of manufacturing them. Heretofore design and manufacturing engineers have been faced with the complex problems of designing and manufacturing shell cases that have a suitable factor of safety and yet enough elasticity to return to their original dimensions after removal of the stresses developed by the rapidly expanding gases that tend to deform a shell case radially when a gun is fired. The elastic limit of the materials used must be such that no permanent set remains so that the shell case may be easily automatically gas-expelled, manually removed or otherwise mechanically ejected from the gun.

Moreover, as the speed of targets increases, the guns used to fire at them have their firing rate increased and the ejection problem is made more difficult due to the elevated temperatures encountered when a gun res many rounds in succession. Furthermore, ease and speed of ejection becomes important in order to permit increased firing rates with safety in that the bore and breech must be cleared7 between the firing of successive rounds to preclude hang fires etc.

While shell cases made of a winding of sheet metal secured to a base have in part been an answer to the above problems, since they permit relative movement of the layers to effect radial expansion of the shell case; cases thus constructed have limitations in that some of them will partially unwind due to impacts that they may be subjected to, as for example, in being transported during operations in the field. Moreover, if the shell case is of the type secured to a deformable base by positioning one end of the winding, comprising a tubular portion, into a groove in the base and then subjecting the assembly to a high internal fluid pressure while in a mold an additional limitation is encountered in that rejects will be found since some cases will unwind after molding operations.

It can readily be seen that fastening or securing the layers in multi-layer wound shell cases by the known methods of welding, riveting, and by tenons not permitting relative movement between the layers does not solve the problems and shell cases so constructed are subject to the above mentioned problems of the possibility of surpassing the elastic limit of the material so that removal of the expended shell case from a guns breech may well be made impossible after ring.

It is a principal object of the invention to provide a shell case overcoming all of the above mentioned problems and limitations of the known types of shell cases.

Another object is to provide a shell case simple and inexpensive to manufacture and permitting present equip- Fice ment to be used to construct or manufacture shell cases according to the invention.

Still another object is to provide a method of manufacture without adding to the labor cost of manufacture by requiring additional operations.

A feature of the shell case in accordance with the invention is that at least one arcuate radially projecting prominence is automatically formed on an inside layer of the multi-layer tubular portion of the shell case during a final molding operation and is slidably engaged with a recess or aperture in an adjacent layer or with a corresponding prominence to releasably lock the layers in fixed relationship regardless of the type impact or shock to which the shell case is subjected. The locking means is unlocked only by radial forces having a predetermined value to permit sliding relative movement between the layers whereby the elastic limit of the material used in constructing the shell case is never reached or exceeded due to the above mentioned radial forces. The elasticity of the assembly is thus maintained permitting easy removal of the shell case after firing.

Other objects, features, and advantages of the invention will be understood from the following description and claims in conjunction with the accompanying drawings which illustrate, by way of example, preferred embodiments of the shell cases, and in which Fig. 1 is a vertical sectional view of the assembled shell case inside a mold and illustrates the molding operation in accordance with the invention.

Fig. 2 is a schematic cross-section View of the shell case taken on line z-z of Fig. 1.

Fig. 2a is a fragmentary cross-section View of the shell case material before fluid pressure is applied.

Fig. 3 is a plan View illustrating the geometry of the sheet material before being wo-und into the tubular portion of the shell case.

Fig. 4 is a fragmentary cross-sectional enlarged view of the releasable locking means, according to the invention, in locked position.

Fig. 5 is a fragmentary cross-sectional enlarged view of the releasable locking means of Fig. 4 shown in unlocked position.

Fig. 6 is a fragmentary vertical sectional view of a triple layer shell case locking means according to the invention.

Fig. 7 is a fragmentary cross-sectional View of the locking means shown in Fig. 6 and taken on lines 7-7.

Fig. 8 is a vertical sectional view of an assembled triple layer shell case and illustrates a construction wherein the locking or connecting means of the invention is not visible externally.

Fig. 9 is a transverse sectional view taken on line 9-9 of Fig. 8.

Fig. l0 is a fragmentary vertical sectional view of an assembled shell case and illustrates another embodiment of the locking means according to the invention.

Fig. 11 is a fragmentary transverse sectional view taken on line 11-11 of Fig. 10.

Fig. 12 is a fragmentary vertical sectional view of an assembled shell case and illustrates another modification 0f the locking means and the method of forming it.

Fig. 13 is a fragmentary cross-section view taken on line 13--13 of Fig. 12.

The shell case in accordance with the invention comprises a multi-layer tubular portion A fixed to a base B (Figs. 1 and 8) by means of an inturned end t fixed in a frusto-conical groove as shown. The tubular portion A is formed by rolling a sheet of metal a having a trapezoidal form (Fig. 3) or any other suitable geometry, so that edge e is positioned internally (Fig. 2) forming an internal helical seam and edge g is positioned external of the winding forming a helical lap joint or seam. The sheet of metal a is provided with an aperture or hole y positioned toward the edge g and adjacent the marginal portion t as shown. The hole y is thus adacent the external helical seam formed by edge g and near the base in the finished shell case.

The lower marginal portion t is bent inwardly by known means and the multi-layer winding of sheet material forming the tubular body of the shell case is assembled with the base B made of a deformable material. The assembly is then placed in a mold M (Fig. l) where a high uid pressure is applied to the interior of the case to mold the case to the size and shape of the mold. During the molding operation the effect of the internally applied uid pressure is to move the layers of the winding outwardly radially against the mold walls so that the tubular portion is molded to its finished shape and dimensions as determined by the mold walls. During the course of the same operation and immediately after the molding of the shell case, the inner layer a1 (Figs. 1, 2a, and 4) has a localized area corresponding with the aperture or hole y deected or deformed outwardly to automatically form `an arcuate radially projecting prominence or protuberance penetrating into the hole or recess y. Thus it can be seen that the layer a2 more particularly the hole y cooperates with layer al to form a rounded protuberance x of such a size as to be capable of sliding movement in said hole or recess y to provide an elastic interlock between the layers to restrain unwinding of the sheet in the manner later herein described.

It will be understood that the fastening or layer interlocking means must be releasable only by non-localized internal forces applied internally of the case or container in radial directions and outwardly directed and must permit circumferential displacement of the layers by movement relative one another in order to meet the conditions encountered in the ring of a gun.

The invention functions as follows:

When the gun is fired the hot and rapidly expanding gases tend to expand the shell case radially so that layer a1 moves circumferentially in the direction of the arrow f1 (Fig. 5) and the layer a2 moves circumferentially in the direction of arrow f2 until the inner walls of the gun breech (not shown) limit any further movement. As the gas pressure diminishes the inherent resiliency of the material and the geometry of the rounded protuberance x move the layers in an opposite direction back into an interlocking position as shown in Fig. 4. Accordingly it can be seen that the arcuate configuration of the protuberance x releasably locks the layers so that during the relative sliding movements of the sheet layers in opposite circumferential directions the elastic limit of the material from which the shell is made is never reached much less exceeded. Accordingly the shell case returns to its initial dimension permitting it to be easily ejected or removed from the gun breech. It will be understood that hole y may be provided with a chamfered edge as shown in Fig. 5 in order to facilitate the above described circumferential movement of the layers and an easy return of the prominence x into registering position with hole y so as to interlock the layers.

It has been found and verified during the course of extensive official tests, wherein twenty thousand rounds were fired, that shell cases made according to the invention never once were hard to extract or eject from the guns in which they are fired. Inspection of the shell cases after firing proved the functioning of the mechanical interlocking means in that score marks were found on the inner side of the layers a2 showing the extent of the movement of the prominence x during the sliding displacement of said layers. The tests proved conclusively that the novel construction of the shell cases resulted in a shell case that could easily be removed after firing and offered no limitations as to manual, mechanical or automatic ejection means and the only limitation on the rate of firing would be the ejection means itself. Accordingly it can be seen that the new and novel interlocking means overcomes the heretofore mentioned limitations in both shell cases made either by windings or by drawing. Moreover, the layer interlocking means is normally in a locked position and maintains the layers in xed relationship when subjected to impacts and vibrations encountered during transportation. The tests disclosed that release of the interlocking means is possible only as heretofore described by internally applied radial forces.

It will be understood that the sheet metal employed in making the cases must have sufficient rigidity so that the prominence x is not crushed or deformed by the firing pressures and particularly when in an unlocked position as shown in Fig. 5 wherein the layers are subjected to elevated pressures while being held against the walls of the gun breech. Thus it can be seen that material while being deformable must not be so easily deformed that attening of the prominence x would be permitted under the above conditions when firing. Furthermore the material must not be readily deformable so that a new prominence is formed in the layer a1 when the hole y is displaced (Fig. 5) relative to the initial prominence formed by the high uid pressures used in molding. In order to satisfy all these requirements the sheet material must be deformable and elastic, as for example, a soft steel sheet having a thickness of the order of 0.5 mm. The diameter of the hole or recess y must not exceed a few millimeters in order that the deformation or prominence x is properly dimensioned so as to have sufficient mechanical strength to resist crushing when subjected to compression forces during ring as heretofore described.

While the releasable layer interlocking means has been described as comprising a single hole y and a registering and interpenetrating deformation, therein providing a mechanical interlocking of the layers to restrain unwinding of the sheet material forming the tubular portion of the case, it will be understood that a plurality of holes and registering prominences can be employed. Where only one hole is used it is preferable to position it as shown in Fig. 3 so that it is near the base and because of the helical outer lap joint or seam the entire length of the seam is effectively held by the one fastening means. It has been found that positioning the fastening means near the open end of the shell case permits partial unwinding near the base.

The invention is applicable to shell cases wherein the tubular portion comprises more than two layers, as for example, as shown in Figs. 6 and 7 wherein a case is made of three layers a0, a1, and a2. The hole y is made Without chamfered edges and is positioned in the outer layer a2 so that the two inner layers are deformed radially to form the nterpenetrating prominences x1 and x2 registering with the hole y as shown. The operation of the fastening means both in the locked and unlocked position is similar to the locking means described with respect to Fig. 4.

Moreover, if it is desired to position the mechanical interlock so that it is not visible on the external periphery of the container or shell case the hole y may be positioned in the intermediate layer a1 (Figs. 8 and 9) so that the registering deformation is formed in layer a0 as shown. Accordingly the mechanical interlock cannot be seen from an external position since outer layer a2 has no discontinuities.

While the invention is directed at a novel mechanical interlock particularly applicable to pressure containers, as for example, shell cases the invention also provides a simple and inexpensive process of making said shell cases without resort to tooling-up with new tools and also permitting the use of existent molding equipment. Accordingly the manufacturing process provides means wherein the mechanical interlock is formed simultaneously with the final molding operation of the shell case inter-locking the layers so that the shell case retains its finish dimensions. Moreover, even though the invention has been described as comprising the deformation of a rounded protuberance into a hole provided in the sheet material for making the shell case it will be understood that the layer fastening means may comprise an inwardly directed radial deformation. Thus prior to winding the sheet of deformable material n a deformation n can be provided therein positioned so that it will be disposed on the intermediate layer al (Figs. and 11) so that the deformation n cooperates with the intern-al pressure when applied to produce a local registering deformation on the innermost layer a0. The registering deformations comprise a mechanical interlock operating in a similar manner to the mechanical interlock means heretofore described. If it is desired to form the mechanical interlock without performing any operations prior to the molding operation the hole y and deformations n may be replaced by a forming means p made of an incompressible material so as to form a localized mechanical interlock as shown when a high fluid pressure is applied to the interior of the case and mold.

Thus it can be seen that a novel method is provided wherein means comprising a hole, a prominence or forming means is positioned between the inner layer of the deformable sheet material and the mold wall to cooperate with a high fluid pressure to form a releasable mechanical interlock in an improved shell case.

While preferred embodiments of the invention have been illustrated and described, it will be understood that the invention is in no way limited to these embodiments and that many changes may be made within the spirit and scope of the invention as defined by the following claims.

What I claim and desire to secure by Letters Patent is:

1. An open-ended shell case having a base provided with an annular groove in one face, a multi-layer tube consisting of wound deformable elastic sheet material and having an external helical seam, means holding one end of said tube clamped in said groove, the other end being free, the improvement which comprises, means providing a slidable mechanical interengagement of superposed layers of said tube comprising, in a part of said layers, local radially oifset portions slidably engaged in an interlocked position by corresponding recesses in adjacent layers adjacent said helical seam and near said clamped end to provide a releasable elastic interlock between superposed layers having their normal diameters and to restrain unwinding of said sheet, said oifset portions forming rounded protuberances of such shape as to be capable of elastic movement in said recesses in opposite circumferential directions of said shell case to permit momentary radial expansions of said tube during tiring without crushing said rounded protuberances of said tube and to produce after tiring its contraction into the interlocked position by contraction due to the elastic character of said sheet material, and the configuration of said protuberances and recesses being so chosen as to facilitate the elastic return of the case layers to the interlocked position.

2. An open-ended shell case comprising, in combination, a base having in one face an annular groove, a multilayer tubular body portion having a helical seam and consisting of a winding of deformable and elastic sheet material having the characteristic of retaining a deformation, one end of said tubular body portion being fastened in said groove to join the body portion and base, a releasable mechanical interlock for providing a slidable mechanical interengagement between said layers to restrain unwinding of said sheet material, said interlock comprising at least one local radial substantially arcuate and rigid prominence formed on at least one of the inner layers of said tubular body portion and the layer super` posed over said inner layer being provided with a recess adjacent said helical seam and near said base, said recess registering with said prominence and slidably en gaging it in an interlocked position, whereby said shell case tube is radially expanded during firing when an internal pressure of a selected value obtains in said shell case for overcoming resistance oifered by the interengagement of said prominence with said recess so as to move said layers circumferentiallyl relative one another, grid is radially contracted to the interlocked position after ring.

3. A shell case according to claim 2, in which said tubular body portion comprises three layers, and in which said recess comprises Ia hole provided in an intermediate layer and said slidable prominence is disposed in the innermost layer, whereby said mechanical interlock is not visible from outside of said shell case.

4. A shell case according to claim 2, in which said tubular body portion comprises at least two layers and the layer having said recess comprises the outermost layer defining the outer periphery of the shell case body portion, and in which said recess comprises a hole, said slidable prominence terminating substantially iiush with the outer periphery of the tubular body portion of the shell case.

5. A shell case according to claim 4, in which said hole has edges defining its dimensions and said edges are chamfered.

6. An open-ended shell case comprising, in combination, a base having in one face an annular groove, a multilayer tubular body portion having a helical seam and consisting of a winding of deformable and elastic sheet material having the characteristic of retaining a deformation, one end of said tubular body portion being fastened in said groove to join the body portion and the base, a releasable mechanical interlock for providing a slidable and elastic interengagement between said layers to restrain unwinding of said sheet material, said interlock comprising a plurality of local registering yand interpenetrating radial deformations directed in an inward direction, said deformations comprising rigid and substantially arcuate prominences positioned on the inner layers of said body portion and having an offset dimension large enough to otter resistance to relative sliding movement of said layers in opposite circumferential directions by all forces below a tirst selected value and to non-localized forces internally applied and radially and outwardly directed below a second selected value, whereby said shell case is radially expansible only when an internal pressure having a value greater than said second selected value obtains in said shell case for overcoming resistance offered by said registering and interpenetrating deformations so as to permit momentary expansion of said case during firing without crushing said protuberances of said tube and to produce its elastic return into the interlocked position after tiring by a suitable elastic force.

References Cited in the file of this patent UNITED STATES PATENTS 42,329 Crispin Apr. 12, 1864 818,731 Adriance et al Apr. 24, 1906 2,193,573 Tackler Mar. 12, 1940 2,397,206 Ryan Mar. 26, 1946 2,397,370 Raven et al. Mar. 26, 1946 2,611,460 Nash Sept. 23, 1952 2,853,945 Stealey Sept. 30, 1958 FOREIGN PATENTS 519,001 France Jan. 14, 1921 826,272 France Jan. 4, 1938 731,748 Germany June 7, 1943 .574,966 Great Britain Jan. 29, 1946

Images