CA2013981C - A method of fabricating firearm cartridge cases, and the cartridge case obtained by implementation of such a method - Google Patents
A method of fabricating firearm cartridge cases, and the cartridge case obtained by implementation of such a methodInfo
- Publication number
- CA2013981C CA2013981C CA002013981A CA2013981A CA2013981C CA 2013981 C CA2013981 C CA 2013981C CA 002013981 A CA002013981 A CA 002013981A CA 2013981 A CA2013981 A CA 2013981A CA 2013981 C CA2013981 C CA 2013981C
- Authority
- CA
- Canada
- Prior art keywords
- tube
- strengthening piece
- base
- piece
- strengthening
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
Links
Classifications
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F42—AMMUNITION; BLASTING
- F42B—EXPLOSIVE CHARGES, e.g. FOR BLASTING, FIREWORKS, AMMUNITION
- F42B5/00—Cartridge ammunition, e.g. separately-loaded propellant charges
- F42B5/26—Cartridge cases
- F42B5/30—Cartridge cases of plastics, i.e. the cartridge-case tube is of plastics
- F42B5/307—Cartridge cases of plastics, i.e. the cartridge-case tube is of plastics formed by assembling several elements
Abstract
a cartridge case is assembled from three pieces, namely a cylindrical tube, a strengthening piece insertable in the tube, and a base ensheathing the end of the tube occupied by the strengthening piece, utilizing a strengthening piece fashioned in a substantially non-deformable material with a ready-made radially projecting flange; the base is open at both ends, and formed with stretches of dissimilar diameter interconnected by a flared reduction the internal surface of which creates a seating by which the flange can be accommodated together with one end of the tube, Having inserted the tube through the smaller diameter of the base a short way into the larger diameter stretch, the strengthening piece is inserted into the base from the opposite direction, located in the tube, and driven forward such that the end of the tube is splayed and sandwiched between the flange and the seating, whereupon it remains only to crimp the excess part of the larger diameter stretch inwards to lock the strengthening piece in place.
Description
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2 BACKGROUND of the INVENTION
The invention relates to a method of fabricating three-piece type cartridge cases, and by extension, to the cartridge case obtainable by implementation of such a method.
05 Cartridge cases, in particular those for guns used in hunting and competition shooting (skeet), are fashioned conventionally by assembling a number of discrete parts consisting but minimally in material of any value, in order to gain economies both in manufacture and ultimately in use, given that such items are generally fired once and discarded.
In the method of fabrication most widely adopted for three-piece cartridge cases, use is made of a tube of plastic or paper material, a cylindrical strengthening piece, also in plastic or paper, and a metal base.
The base appears essentially as a cylinder of which the bottom end is enclosed and enlarged around the periphery by incorporation of a molded rim serving to create an complementary internal seating, and is holed at center to take a cap for detonation of the propellant. The tube, likewise cylindrical, slots into the base until fully abutted with the enclosed _ . J~ s, s~ r.
~s~~ ~ b.~Ju3'~.
The invention relates to a method of fabricating three-piece type cartridge cases, and by extension, to the cartridge case obtainable by implementation of such a method.
05 Cartridge cases, in particular those for guns used in hunting and competition shooting (skeet), are fashioned conventionally by assembling a number of discrete parts consisting but minimally in material of any value, in order to gain economies both in manufacture and ultimately in use, given that such items are generally fired once and discarded.
In the method of fabrication most widely adopted for three-piece cartridge cases, use is made of a tube of plastic or paper material, a cylindrical strengthening piece, also in plastic or paper, and a metal base.
The base appears essentially as a cylinder of which the bottom end is enclosed and enlarged around the periphery by incorporation of a molded rim serving to create an complementary internal seating, and is holed at center to take a cap for detonation of the propellant. The tube, likewise cylindrical, slots into the base until fully abutted with the enclosed _ . J~ s, s~ r.
~s~~ ~ b.~Ju3'~.
3 bottom, and the peripheral edge of the inserted end may also be rolled inwards toward its axis, fox a reason that will become apparent in due course. The strengthening piece is also cylindrical externally, 05 affording a center hole designed to align coaxially with the hole in the base which accommodates the cap, and is fashioned in a deformable material for a reason that will emerge from the brief outline of the conventional method which follows.
For example, the strengthening piece is inserted into one end of the tube, and this preassembled end then pushed full into the base to the point where contact is made with the enclosed bottom; in the event that the edge of the tube is rolled inwards, as aforementioned, the tube will be inserted into the base, and the strengthening piece then inserted into the tube and located against the rolled edge.
Thereafter, with the three pieces positioned one in relation to the other and correctly held in place, a compressive force is applied to the strengthening piece, which under the resultant stress is required to perform two basic functions: first, to compress the tube against the internal cylindrical surface of the base, and second, to deform the rolled edge of the tube radially in such a way as forces it ~~
~ /
~i ~ ~.~''~ ~1 '~ ~.z.
For example, the strengthening piece is inserted into one end of the tube, and this preassembled end then pushed full into the base to the point where contact is made with the enclosed bottom; in the event that the edge of the tube is rolled inwards, as aforementioned, the tube will be inserted into the base, and the strengthening piece then inserted into the tube and located against the rolled edge.
Thereafter, with the three pieces positioned one in relation to the other and correctly held in place, a compressive force is applied to the strengthening piece, which under the resultant stress is required to perform two basic functions: first, to compress the tube against the internal cylindrical surface of the base, and second, to deform the rolled edge of the tube radially in such a way as forces it ~~
~ /
~i ~ ~.~''~ ~1 '~ ~.z.
4 into the seating created within the molded rim of the base. During such an operation, considerable mechanical stresses are applied to the materials both of the tube, and of the strengthening piece in 05 particular, which can cause irreparable damage if not properly controlled. For example, if too great a force is applied to the strengthening piece, the stretch of the tube inserted into the base may be pinched too tightly and its ability to withstand tensile stress thus weakened, resulting in a loss of strength when the cartridge is fired.
This complex and delicate assembly is nonetheless indispensable in order to ensure that the tube does not separate from the base on detonation of the charge and enter the barrel of the gun, of which the consequences would clearly be hazardous.
This same assembly procedure serves also to ensure that the base of the cartridge, accommodating the cap and bolstered by the strengthening piece, will afford firm resistance to the firing pin of the gun at the moment when the cap is struck; the requisite properties of rigidity and strength, which can be.
ensured only where relative movement between the three pieces is disallowed, roust be calculated with absolute precision to avoid any risk of irregular initiation and detonation of the charge.
A further aim of the operation in question is to eliminate or at least to minimize the leakages of combustion gas that tend to occur from between the 05 tube and the strengthening piece, which distort the base and thus affect the dimensional structure of the cartridge case.
Numeronis intrinsic. problems are thus posed in the assembly operation, first among which is the need for technically complex and high powered machinery, given the requirement for a considerable force to b~~ generated internally of a restricted space such as that afforded by a cartridge case. Moreover, the part of the machine that engages the strengthening piece and invests it with the compressive force roust be of a precise shape, in order to permit of applying the force correctly to ensure a tight union of the three pieces and obtain the desired rigidity of the base.
Neither is it possible to ignore the many external factors adversely affecting the assembly operation and tending to inhibit a firm association between the three pieces. Among such adverse factors are the restrictive dimensions of the seating afforded by the molded rim of the base, the difficulty of ~~, . ~ c; ~ r G
'.J .~.
bringing about a repeatable and uniform insertion of the tube and strengthening piece materials into the seating to provide an efficient anchorage, and the possible tendency of the elastic strengthening 05 material to regain its original shape.
This entire range of factors is aggravated further by the obvious difficulty of verifying with the aid of non-destructive technical or visual means that forcing of the strengthening piece has resulted in the successful formation of a lip internally of the base seating, this being in effect the one element capable of ensuring a positive connection between the three component pieces.
Accordingly, the object of the present invention is to provide a method of fabricating three-piece type cartridge cases whereby. the connection of the three pieces can be maintained secure from assembly right through detonation and c7ischarge without the aid of powerful compressive forces during assembly tending to deform and thus alter the geometry of one or more of the component parts of the case.
A further object of the invention is to permit of assembling cartridge cases by adoption of a simple, rational and economic method capable of overcoming ' the drawbacks mentioned above.
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SUMMARY of the INVENTION
The stated objects are realized comprehensively by adoption of a cartridge case design as disclosed, 05 of which the essential feature is that no reliance is placed on deformation of the strengthening piece to obtain a tight fit between the three component parts; instead, by utilizing an open bottomed base and a strengthening piece fashioned in essentially rigid material with the necessary retaining flange already incorporated, and inserting the tube and the strengthening piece into the base from opposite directions, the need for high compressive forces is dispensed with, and it remains simply to crimp the open bottom of the base in toward the center.
BRIEF DESCRIPTION of the DRAWINGS
The invention will now be described in detail, by way of example, with the aid of the accompanying drawings, in which;
-fig 1 illustrates the three pieces of a cartridge case according to the invention, in axial section, seen in readiness for assembly by implementation of the method disclosed;
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ø~ .W. ~i ti rl .3 figs 2...4 are further axial sections of the three pieces of fig 1, seen during successive steps of the method disclosed;
-fig 5 illustrates a different embodiment of the 05 cartidge case of fig 4, seen in axial section;
-figs 6...8 illustrate three different embodiments of the strengthening piece shown in fig 1.
DESCRIPTION of the PREFERRED EMBODIMENTS
Referring now to the drawings, the method according to the present invention permits of fabricating a cartridge case, denoted l in its entirety, embodied in three component parts: a cylindrical tube 2, a 15 strengthening piece 3 insertable into the tube, and a base 4.
The method disclosed consists first and foremost in fashioning a basically cylindrical strengthening piece 3 from essentially non-deformable material, 20 of shape such at least as to exhibit a peripheral lip, or flange, denoted 3l, which in the example illustrated exhibits a maximum diameter 3d greater than the maximum diameter 2d of the tube, and is flared in relation to the cylindrical surface of 25 the component.
. ,/, /,. ,"A !"j !~, i A 7 . i 'J 'J ~/
Needless to say, the strengthening piece 3 will be non-deformable not in any absolute sense, but only insofar as no deforrnation occurs during the steps of the method disclosed. Also, reference to the 05 strengthening piece 3 of a. cartridge case according to the invention as being non-deformable permits conveniently of drawing a clear distinction with the corresponding component in a conventional cartridge case, of which the drastic deformation undergone during assembly is such as to alter both its geometry and its mechanical properties; whereas the application of a strong compressive force is intended conventionally to enhance rigidity of the flat bottom of the base, this very notion places a marked limitation on the number of profiles that can be adopted for the strengthening piece, which in the finished cartridge is positioned in dixect contact with the propellant.
mhe method according to the invention comprises the further expedient of adopting a base 4 embodied with two coaxial stretches 4l and 42 of dissimilar internal diameter 41d and 42d, respectively, of ;
which the smaller diameter Old is substantially equal to the external diameter 2d of the tube 2, and the larger diameter 42d is substantially equal A ;~ f) ~.
t~ ~. ~3 ~ ~.3 .~.
to the maximum diameter 3d of the flange 31 of the strengthening piece 3. The two coaxial stretches 41 and 42 are interconnected by a stretch 43 serving to create a peripheral rim, matched in profile with 05 the flared flange 31 of the strengthening piece 3, internally of which a complementary seating 45 is afforded of dimensions such as to accommodate the flange 31 and one end 21 of the tube 2 together.
Utilizing a strengthening piece 3 and a base 4 10 embodied thus, the method disclosed comprises the following steps:
-insertion of the tube 2 into the base 4 to the point where the inserted end 21 projects beyond the level, denoted 44, at which the smaller diameter stretch 41 of the base 4 merges with the rim 43, by a distance 1 not less than the axial dimension of the peripheral flange 31 (fig 2);
-insertion of the strengthening piece 3 into the base 4 and into the projecting end 21 of the tube 2 in such a way that the projecting end 21 is splayed and driven into contact with the internal wall of the seating 45 (fig 3);
-folding of the larger diameter stretch 42 of the base 4 in toward center to the point where contact is made with the strengthening piece 3 (fig 4).
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The length 1 of the inserted end 21 of the tube 2 may vary from the rninimum shown in fig 4, in which case the flange 31 of the strengthening piece 3 registers in direct contact with the inside wall of 05 the larger diameter stretch 42 of the base 4, up to a maximum that exceeds the.axial dimension of the flange 31, measured parallel to its generators, in such a way that the tube projects into the larger diameter stretch 42 to the point of enveloping the flange 31 entirely (see fig 5). In this instance, the outer diameter 3d of the peripheral flange 31 will be substantially equivalent to the internal diameter 42d of the relative stretch of the base 4, minus twice the thickness s of the tube 2.
It will be apparent immediately that the method disclosed hinges on the adoption of a strengthening piece that is preformed, and can be assembled with other components to create a rigid fabricated whole by exploiting an established geometry that remains unaltered throughout the assembl y procedure.
Expressed in other terms, the stability of the fit between tube 2, strengthening piece 3 and base 4 is ensured by a geometrical shape that is discernible and verifiable prior to assembly and remains stable right through to completion of the assembly steps.
- 4' l~!!'iv~i~l ' ~ ~./ . :9 .l J .%.
Accordingly, the machine used to lock together the three components, namely the tube 2, strengthening piece 3 and base 4, will be a simple and economical item of equipment when compared with the machines 05 currently in use; thus, the costs of manufacturing cartridge cases can be cut drastically by virtue of the substantially smaller capital outlay, and the significant savings in expenditure on labor, raw materials and maintenance of the equipment. In the case of conventional equipment currently in use, in effect, where one has considerable forces unleashed in confined spaces such as that encompassed by a cartridge tube, servicing of the higher precision machines (presses in particular) is essentially an on-going process. As to the consumption of raw materials, this is undoubtedly reduced by adoption of the method disclosed, inasmuch as the base 4 is of open design rather than enclosed as in prior art embodiments. What is more, the method disclosed permits of eliminating the operation of roll-edging one end of the tube 2 in order to improve tYie fit between the three components.
As illustrated in fig 4, a typical cartridge case 1 obtained by implementation of the method disclosed will be seen to consist in a tube 2, an open-ended base 4 ensheathing the tube, and a strengthening piece 3 that is embodied with a radially projecting peripheral flange 31 and inserted into the tube.
Given that the strengthening piece 3 is not subject 05 to appreciable deformation during assembly, it can be embodied with the geometrical shape best able to ensure that the cartridge case 1 is as functional and ballistically effective as possible.
For example, 38 denotes the part of the piece 3 in contact caith the propellant, which might be cupped as illustrated in the drawings; this part could be embodied faith projections 33 disposed peripherally about an axial hole 32 in the strengthening piece 3 which serves to accommodate a detonation cap 5.
Such projections 33 have the function of ensuring that the propellant powder, which is subsequently packed into the cup 38, does not smother the fire issuing from the cap 5 seated in the hole 32, and might be embodied as a plurality of fins radiating from the hole; in positive terms, the fins serve to increase the propagation front of the flame thrown by the cap 5.
The axial hole32 in the strengthening piece 3 might be embodied in a variety of ways in order to enable the accommodation of different types of cap 5; the hole 32 could incorporate a rigid elernent 34, for , example, serving as the anvil for a conventional "Berdan" type cap (fig 7).
In a further embodiment, the strengthening piece 3 05 could exhibit a peripheral groove 35, and created between the groove 35 and the cup 38, a web 37 that is able to flex in the face of thrust generated by the detonating powder. In this type of embodiment, the flexibility of the web 37 remains compatible with the essentially non-deformable characteristic of the strengthening piece 3 described earlier. In effect, the web 37 undergoPS no defarmation during assembly of the three components of the cartridge case, even as a result of such forces as may be generated in the course of the procedure, though deformation is indeed envisaged thereafter, when the cartridge is discharged and becomes subject to forces infinitely greater in absalute terms than those attributable to the steps of the method as described above.
Fig 8 illustrates an embodiment of particular ' interest as regards the question of saving on raw materials. More e:~actly, the strengthening piece 3 is relieved of matserial at points 36 on the side 25, accommodated by the larger diameter stretch 42 of ~: , ~ ~.,~ ~ r .~, ~.3 ~1 ~ .~e.
the base, and in the case in question, simply by sinking a number of blind holes. Such an expedient is made possible by virtue of the fact that the piece is not subject to any deforming stress worthy 05 of note during assembly of 'the cartridge case 1, and being thus able to retain its shape unaffected, can be embodied with any given geometry provided that the peripheral flange 31 is included.
The method disclosed provides a facility not found 10 in'prior art cartridge case manufacture, namely, of selecting the geometry of the strengthening piece 3 according to the features it may be sought to build into the cartridge case; the strengthening piece 3 thus plays an active role in fabrication, given 15 that a variation in its shape has material bearing on the performance of the finished cartridge.
This complex and delicate assembly is nonetheless indispensable in order to ensure that the tube does not separate from the base on detonation of the charge and enter the barrel of the gun, of which the consequences would clearly be hazardous.
This same assembly procedure serves also to ensure that the base of the cartridge, accommodating the cap and bolstered by the strengthening piece, will afford firm resistance to the firing pin of the gun at the moment when the cap is struck; the requisite properties of rigidity and strength, which can be.
ensured only where relative movement between the three pieces is disallowed, roust be calculated with absolute precision to avoid any risk of irregular initiation and detonation of the charge.
A further aim of the operation in question is to eliminate or at least to minimize the leakages of combustion gas that tend to occur from between the 05 tube and the strengthening piece, which distort the base and thus affect the dimensional structure of the cartridge case.
Numeronis intrinsic. problems are thus posed in the assembly operation, first among which is the need for technically complex and high powered machinery, given the requirement for a considerable force to b~~ generated internally of a restricted space such as that afforded by a cartridge case. Moreover, the part of the machine that engages the strengthening piece and invests it with the compressive force roust be of a precise shape, in order to permit of applying the force correctly to ensure a tight union of the three pieces and obtain the desired rigidity of the base.
Neither is it possible to ignore the many external factors adversely affecting the assembly operation and tending to inhibit a firm association between the three pieces. Among such adverse factors are the restrictive dimensions of the seating afforded by the molded rim of the base, the difficulty of ~~, . ~ c; ~ r G
'.J .~.
bringing about a repeatable and uniform insertion of the tube and strengthening piece materials into the seating to provide an efficient anchorage, and the possible tendency of the elastic strengthening 05 material to regain its original shape.
This entire range of factors is aggravated further by the obvious difficulty of verifying with the aid of non-destructive technical or visual means that forcing of the strengthening piece has resulted in the successful formation of a lip internally of the base seating, this being in effect the one element capable of ensuring a positive connection between the three component pieces.
Accordingly, the object of the present invention is to provide a method of fabricating three-piece type cartridge cases whereby. the connection of the three pieces can be maintained secure from assembly right through detonation and c7ischarge without the aid of powerful compressive forces during assembly tending to deform and thus alter the geometry of one or more of the component parts of the case.
A further object of the invention is to permit of assembling cartridge cases by adoption of a simple, rational and economic method capable of overcoming ' the drawbacks mentioned above.
s 6 ly i! ' ~; :j / ~'., ~~~~.3:i~
SUMMARY of the INVENTION
The stated objects are realized comprehensively by adoption of a cartridge case design as disclosed, 05 of which the essential feature is that no reliance is placed on deformation of the strengthening piece to obtain a tight fit between the three component parts; instead, by utilizing an open bottomed base and a strengthening piece fashioned in essentially rigid material with the necessary retaining flange already incorporated, and inserting the tube and the strengthening piece into the base from opposite directions, the need for high compressive forces is dispensed with, and it remains simply to crimp the open bottom of the base in toward the center.
BRIEF DESCRIPTION of the DRAWINGS
The invention will now be described in detail, by way of example, with the aid of the accompanying drawings, in which;
-fig 1 illustrates the three pieces of a cartridge case according to the invention, in axial section, seen in readiness for assembly by implementation of the method disclosed;
!f, ~ _' j :,'~, ~ J
ø~ .W. ~i ti rl .3 figs 2...4 are further axial sections of the three pieces of fig 1, seen during successive steps of the method disclosed;
-fig 5 illustrates a different embodiment of the 05 cartidge case of fig 4, seen in axial section;
-figs 6...8 illustrate three different embodiments of the strengthening piece shown in fig 1.
DESCRIPTION of the PREFERRED EMBODIMENTS
Referring now to the drawings, the method according to the present invention permits of fabricating a cartridge case, denoted l in its entirety, embodied in three component parts: a cylindrical tube 2, a 15 strengthening piece 3 insertable into the tube, and a base 4.
The method disclosed consists first and foremost in fashioning a basically cylindrical strengthening piece 3 from essentially non-deformable material, 20 of shape such at least as to exhibit a peripheral lip, or flange, denoted 3l, which in the example illustrated exhibits a maximum diameter 3d greater than the maximum diameter 2d of the tube, and is flared in relation to the cylindrical surface of 25 the component.
. ,/, /,. ,"A !"j !~, i A 7 . i 'J 'J ~/
Needless to say, the strengthening piece 3 will be non-deformable not in any absolute sense, but only insofar as no deforrnation occurs during the steps of the method disclosed. Also, reference to the 05 strengthening piece 3 of a. cartridge case according to the invention as being non-deformable permits conveniently of drawing a clear distinction with the corresponding component in a conventional cartridge case, of which the drastic deformation undergone during assembly is such as to alter both its geometry and its mechanical properties; whereas the application of a strong compressive force is intended conventionally to enhance rigidity of the flat bottom of the base, this very notion places a marked limitation on the number of profiles that can be adopted for the strengthening piece, which in the finished cartridge is positioned in dixect contact with the propellant.
mhe method according to the invention comprises the further expedient of adopting a base 4 embodied with two coaxial stretches 4l and 42 of dissimilar internal diameter 41d and 42d, respectively, of ;
which the smaller diameter Old is substantially equal to the external diameter 2d of the tube 2, and the larger diameter 42d is substantially equal A ;~ f) ~.
t~ ~. ~3 ~ ~.3 .~.
to the maximum diameter 3d of the flange 31 of the strengthening piece 3. The two coaxial stretches 41 and 42 are interconnected by a stretch 43 serving to create a peripheral rim, matched in profile with 05 the flared flange 31 of the strengthening piece 3, internally of which a complementary seating 45 is afforded of dimensions such as to accommodate the flange 31 and one end 21 of the tube 2 together.
Utilizing a strengthening piece 3 and a base 4 10 embodied thus, the method disclosed comprises the following steps:
-insertion of the tube 2 into the base 4 to the point where the inserted end 21 projects beyond the level, denoted 44, at which the smaller diameter stretch 41 of the base 4 merges with the rim 43, by a distance 1 not less than the axial dimension of the peripheral flange 31 (fig 2);
-insertion of the strengthening piece 3 into the base 4 and into the projecting end 21 of the tube 2 in such a way that the projecting end 21 is splayed and driven into contact with the internal wall of the seating 45 (fig 3);
-folding of the larger diameter stretch 42 of the base 4 in toward center to the point where contact is made with the strengthening piece 3 (fig 4).
~?, f ~ i1 ~I ~'y 1 'n ;~ .s. :3 J 'J .:..
The length 1 of the inserted end 21 of the tube 2 may vary from the rninimum shown in fig 4, in which case the flange 31 of the strengthening piece 3 registers in direct contact with the inside wall of 05 the larger diameter stretch 42 of the base 4, up to a maximum that exceeds the.axial dimension of the flange 31, measured parallel to its generators, in such a way that the tube projects into the larger diameter stretch 42 to the point of enveloping the flange 31 entirely (see fig 5). In this instance, the outer diameter 3d of the peripheral flange 31 will be substantially equivalent to the internal diameter 42d of the relative stretch of the base 4, minus twice the thickness s of the tube 2.
It will be apparent immediately that the method disclosed hinges on the adoption of a strengthening piece that is preformed, and can be assembled with other components to create a rigid fabricated whole by exploiting an established geometry that remains unaltered throughout the assembl y procedure.
Expressed in other terms, the stability of the fit between tube 2, strengthening piece 3 and base 4 is ensured by a geometrical shape that is discernible and verifiable prior to assembly and remains stable right through to completion of the assembly steps.
- 4' l~!!'iv~i~l ' ~ ~./ . :9 .l J .%.
Accordingly, the machine used to lock together the three components, namely the tube 2, strengthening piece 3 and base 4, will be a simple and economical item of equipment when compared with the machines 05 currently in use; thus, the costs of manufacturing cartridge cases can be cut drastically by virtue of the substantially smaller capital outlay, and the significant savings in expenditure on labor, raw materials and maintenance of the equipment. In the case of conventional equipment currently in use, in effect, where one has considerable forces unleashed in confined spaces such as that encompassed by a cartridge tube, servicing of the higher precision machines (presses in particular) is essentially an on-going process. As to the consumption of raw materials, this is undoubtedly reduced by adoption of the method disclosed, inasmuch as the base 4 is of open design rather than enclosed as in prior art embodiments. What is more, the method disclosed permits of eliminating the operation of roll-edging one end of the tube 2 in order to improve tYie fit between the three components.
As illustrated in fig 4, a typical cartridge case 1 obtained by implementation of the method disclosed will be seen to consist in a tube 2, an open-ended base 4 ensheathing the tube, and a strengthening piece 3 that is embodied with a radially projecting peripheral flange 31 and inserted into the tube.
Given that the strengthening piece 3 is not subject 05 to appreciable deformation during assembly, it can be embodied with the geometrical shape best able to ensure that the cartridge case 1 is as functional and ballistically effective as possible.
For example, 38 denotes the part of the piece 3 in contact caith the propellant, which might be cupped as illustrated in the drawings; this part could be embodied faith projections 33 disposed peripherally about an axial hole 32 in the strengthening piece 3 which serves to accommodate a detonation cap 5.
Such projections 33 have the function of ensuring that the propellant powder, which is subsequently packed into the cup 38, does not smother the fire issuing from the cap 5 seated in the hole 32, and might be embodied as a plurality of fins radiating from the hole; in positive terms, the fins serve to increase the propagation front of the flame thrown by the cap 5.
The axial hole32 in the strengthening piece 3 might be embodied in a variety of ways in order to enable the accommodation of different types of cap 5; the hole 32 could incorporate a rigid elernent 34, for , example, serving as the anvil for a conventional "Berdan" type cap (fig 7).
In a further embodiment, the strengthening piece 3 05 could exhibit a peripheral groove 35, and created between the groove 35 and the cup 38, a web 37 that is able to flex in the face of thrust generated by the detonating powder. In this type of embodiment, the flexibility of the web 37 remains compatible with the essentially non-deformable characteristic of the strengthening piece 3 described earlier. In effect, the web 37 undergoPS no defarmation during assembly of the three components of the cartridge case, even as a result of such forces as may be generated in the course of the procedure, though deformation is indeed envisaged thereafter, when the cartridge is discharged and becomes subject to forces infinitely greater in absalute terms than those attributable to the steps of the method as described above.
Fig 8 illustrates an embodiment of particular ' interest as regards the question of saving on raw materials. More e:~actly, the strengthening piece 3 is relieved of matserial at points 36 on the side 25, accommodated by the larger diameter stretch 42 of ~: , ~ ~.,~ ~ r .~, ~.3 ~1 ~ .~e.
the base, and in the case in question, simply by sinking a number of blind holes. Such an expedient is made possible by virtue of the fact that the piece is not subject to any deforming stress worthy 05 of note during assembly of 'the cartridge case 1, and being thus able to retain its shape unaffected, can be embodied with any given geometry provided that the peripheral flange 31 is included.
The method disclosed provides a facility not found 10 in'prior art cartridge case manufacture, namely, of selecting the geometry of the strengthening piece 3 according to the features it may be sought to build into the cartridge case; the strengthening piece 3 thus plays an active role in fabrication, given 15 that a variation in its shape has material bearing on the performance of the finished cartridge.
Claims (14)
1) A method of fabricating firearm cartridge cases in three pieces:
-a cylindrical tube of plastic or paper material;
-an essentially cylindrical strengthening piece fashioned in substantially non-deformable material, insertable in one end of the tube and incorporating at least one radially projecting peripheral lip or flange at one end, of which the maximum external diameter is not less than the external diameter of the tube, and the profile flared in relation to the cylindrical surface;
-an open-ended base, ensheathing at least the end of the tube occupied by the strengthening piece and embodied in two successive coaxial stretches of dissimilar internal diameter, the smaller diameter substantially equal to the external diameter of the tube and the larger substantially equal to the external diameter of the peripheral flange of the strengthening piece, which are interconnected by a further stretch exhibiting a flared profile matched to that of the flange of the strengthening piece and serving to establish a peripheral external rim and a complementary internal seating in which to accommodate both the flange of the strengthening piece and the end of the tube together;
comprising the steps of:
-inserting the tube into the base to the point where the inserted end projects beyond the level at which the smaller diameter stretch of the base merges with the peripheral rim, by a distance not less than the axial length of the flare generator of the rim;
-inserting the strengthening piece into the base and into the projecting end of the tube in such a way that the projecting end deforms and is driven by the non-deformable flange into close and uniform contact with the seating afforded internally by the peripheral rim of the base;
-rolling, crimping or otherwise folding the larger diameter stretch of the base into contact with the encompassed strengthening piece.
-a cylindrical tube of plastic or paper material;
-an essentially cylindrical strengthening piece fashioned in substantially non-deformable material, insertable in one end of the tube and incorporating at least one radially projecting peripheral lip or flange at one end, of which the maximum external diameter is not less than the external diameter of the tube, and the profile flared in relation to the cylindrical surface;
-an open-ended base, ensheathing at least the end of the tube occupied by the strengthening piece and embodied in two successive coaxial stretches of dissimilar internal diameter, the smaller diameter substantially equal to the external diameter of the tube and the larger substantially equal to the external diameter of the peripheral flange of the strengthening piece, which are interconnected by a further stretch exhibiting a flared profile matched to that of the flange of the strengthening piece and serving to establish a peripheral external rim and a complementary internal seating in which to accommodate both the flange of the strengthening piece and the end of the tube together;
comprising the steps of:
-inserting the tube into the base to the point where the inserted end projects beyond the level at which the smaller diameter stretch of the base merges with the peripheral rim, by a distance not less than the axial length of the flare generator of the rim;
-inserting the strengthening piece into the base and into the projecting end of the tube in such a way that the projecting end deforms and is driven by the non-deformable flange into close and uniform contact with the seating afforded internally by the peripheral rim of the base;
-rolling, crimping or otherwise folding the larger diameter stretch of the base into contact with the encompassed strengthening piece.
2) A method as in claim 1, wherein the maximum external diameter of the peripheral flange of the strengthening piece is substantially equal to the greater internal diameter of the base minus twice the thickness of the tube.
3) A method as in claim 1, wherein the inserted end of the tube projects beyond the level at which the smaller diameter stretch of the base merges with the peripheral rim, by a'distance not less than the axial length of the flare generator of the rim.
4) A method as in claim 1, wherein the inserted end of the tube projects beyond the level at which the smaller diameter stretch of the base merges with the peripheral rim by a distance not less than the axial length of the flare generator of the rim, and with the strengthening piece fully inserted into the base and the tube, no farther than the bottom face of the strengthening piece.
5) A method as in claim 1, wherein the inserted end of the tube projects beyond the level at which the smaller diameter stretch of the base merges with the peripheral rim by a distance not less than the axial length of the flare generator of the rim, and with the strengthening piece fully inserted into the base and the tube, beyond the strengthening piece by a distance such as enables its compression and retention between a folded edge of the larger diameter stretch of the base and the bottom face of the strengthening piece.
6) A three-piece cartridge case obtainable by implementation of the method of preceding claims, comprising:
-a cylindrical tube;
-a cylindrical, hollow base designed to ensheath one end of the tube, fully penetrable from either end and exhibiting stretches of dissimilar diameter interconnected by a further stretch constituting an external rim and a complementary internal seating;
-a strengthening piece insertable in the tube, fashioned in a material that remains substantially non-deformable throughout the assembly steps of the method, and embodied with a peripheral flange at one end that can be accommodated internally of the seating together with a corresponding part of the ensheathed end of the tube, whereupon a projecting edge of the larger diameter stretch of the base is folded in toward the axis of the case in such a way as to enclose the seating and force the flange and the corresponding end of the tube against the internal surface of the rim to which the seating is complementary.
-a cylindrical tube;
-a cylindrical, hollow base designed to ensheath one end of the tube, fully penetrable from either end and exhibiting stretches of dissimilar diameter interconnected by a further stretch constituting an external rim and a complementary internal seating;
-a strengthening piece insertable in the tube, fashioned in a material that remains substantially non-deformable throughout the assembly steps of the method, and embodied with a peripheral flange at one end that can be accommodated internally of the seating together with a corresponding part of the ensheathed end of the tube, whereupon a projecting edge of the larger diameter stretch of the base is folded in toward the axis of the case in such a way as to enclose the seating and force the flange and the corresponding end of the tube against the internal surface of the rim to which the seating is complementary.
7) A cartridge case as in claim 6, wherein the strengthening piece affords an axial hole serving to accommodate a detonation cap, and is provided at the emergence of the hole onto the surface offered directly to the propellant powder with a plurality of projections of which the purpose is to prevent powder packed into the tube from smothering the flame generated by the cap.
8) A cartridge case as in claim 7, wherein the projections provided at the emergence of the axial hale unto the surface of the strengthening piece offered to the propellant powder are embodied as a plurality of fins radiating from the hole.
9) A cartridge case as in claim 7, wherein the shape of the axial hole in the strengthening piece is matched to the shape of the accommodated cap.
10) A cartridge case as in claim 9, wherein a given proportion of the axial hole of the strengthening piece is occupied by a coaxial element serving as the anvil for a cap accommodated by the remaining proportion of the hole.
11) A cartridge case as in claim 6, wherein shape and geometry of the strengthening piece are selected to the end of maximizing ballistic performance and intrinsic safety of the cartridge, without any restriction attributable to assembly requirements.
12) A cartridge case as in claim 6, wherein shape and geometry of the strengthening piece are selected, without any restriction attributable to assembly requirements, in such a manner that at least the part farthest inside the tube is rendered axially flexible in the face of thrust generated by the propellant in combustion.
13) A cartridge case as in claim 12, wherein the strengthening piece exhibits a peripheral groove isolated from the propellant by a web of thickness such as to enable flexing movement in the face of thrust generated by the propellant in combustion.
14) A cartridge case as in claim 6, wherein the face of the strengthening piece not in contact with the propellant is relieved of material by the formation of at least one concavity or indentation.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| IT3784A/89 | 1989-12-22 | ||
| IT3784A IT1235986B (en) | 1989-12-22 | 1989-12-22 | METHOD FOR THE REALIZATION OF BOSSOLI FOR FIREARMS AND BOSSOLO SO OBTAINED |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CA2013981A1 CA2013981A1 (en) | 1991-06-22 |
| CA2013981C true CA2013981C (en) | 1999-08-24 |
Family
ID=11111702
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002013981A Expired - Fee Related CA2013981C (en) | 1989-12-22 | 1990-04-05 | A method of fabricating firearm cartridge cases, and the cartridge case obtained by implementation of such a method |
Country Status (11)
| Country | Link |
|---|---|
| EP (1) | EP0435830B1 (en) |
| CN (1) | CN1023512C (en) |
| AT (1) | ATE99044T1 (en) |
| AU (1) | AU635990B2 (en) |
| BR (1) | BR9006561A (en) |
| CA (1) | CA2013981C (en) |
| DE (1) | DE69005432T2 (en) |
| ES (1) | ES2047306T3 (en) |
| IT (1) | IT1235986B (en) |
| RU (1) | RU2069302C1 (en) |
| YU (1) | YU241390A (en) |
Families Citing this family (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5710391A (en) * | 1993-10-12 | 1998-01-20 | Chetcuti; Francis | Recoil reducer wad for ammunition |
| WO1998048238A1 (en) * | 1997-04-21 | 1998-10-29 | Tomscot Hb | Shotgun cartridge case-sleeve and a cartridge made therefrom |
| US6164209A (en) * | 1998-12-21 | 2000-12-26 | Olin Corporation | Shotshell basewad |
| FR2926133B1 (en) * | 2008-01-09 | 2010-01-22 | France Cheddite | METHOD FOR MANUFACTURING CYLINDERS FOR CARTRIDGE SLEEVES AND COMPOSITION. |
| DE102008034660B4 (en) * | 2008-07-25 | 2012-03-08 | Rheinmetall Waffe Munition Gmbh | cartridge ammunition |
Family Cites Families (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB191202430A (en) * | 1912-01-26 | 1912-12-05 | James Yate Johnson | Improvements in Aluminium Catridge Cases. |
| FR1430385A (en) * | 1965-01-22 | 1966-03-04 | Gevelot Sa | Process for manufacturing cartridges, and cartridges obtained by this process |
| GB1152193A (en) * | 1965-07-23 | 1969-05-14 | Fiocchi Spa Giulio | Sporting Cartridge Case |
| DE1578223A1 (en) * | 1966-09-21 | 1971-11-25 | Fiocchi Spa Giulio | Cartridge case for shotguns |
| FR1553453A (en) * | 1967-02-27 | 1969-01-10 | ||
| US3565008A (en) * | 1968-06-26 | 1971-02-23 | Olin Mathieson | Plastic shotshell and method |
| US3675576A (en) * | 1970-02-18 | 1972-07-11 | Colorado Business Dev Corp | Reloadable two-piece shotgun cartridge |
| US4867066A (en) * | 1988-10-21 | 1989-09-19 | Olin Corporation | Shotshell casing with reduced volume basewad and increased interior volume for larger shot loads |
-
1989
- 1989-12-22 IT IT3784A patent/IT1235986B/en active IP Right Grant
-
1990
- 1990-04-05 CA CA002013981A patent/CA2013981C/en not_active Expired - Fee Related
- 1990-04-06 AT AT90830153T patent/ATE99044T1/en not_active IP Right Cessation
- 1990-04-06 ES ES90830153T patent/ES2047306T3/en not_active Expired - Lifetime
- 1990-04-06 DE DE90830153T patent/DE69005432T2/en not_active Expired - Fee Related
- 1990-04-06 EP EP90830153A patent/EP0435830B1/en not_active Expired - Lifetime
- 1990-12-19 AU AU68256/90A patent/AU635990B2/en not_active Ceased
- 1990-12-21 YU YU241390A patent/YU241390A/en unknown
- 1990-12-21 BR BR909006561A patent/BR9006561A/en not_active IP Right Cessation
- 1990-12-21 RU SU904894136A patent/RU2069302C1/en active
- 1990-12-21 CN CN91100743A patent/CN1023512C/en not_active Expired - Lifetime
Also Published As
| Publication number | Publication date |
|---|---|
| EP0435830B1 (en) | 1993-12-22 |
| CN1054131A (en) | 1991-08-28 |
| YU241390A (en) | 1994-11-15 |
| IT1235986B (en) | 1992-12-15 |
| AU635990B2 (en) | 1993-04-08 |
| AU6825690A (en) | 1991-06-27 |
| CA2013981A1 (en) | 1991-06-22 |
| DE69005432D1 (en) | 1994-02-03 |
| RU2069302C1 (en) | 1996-11-20 |
| ES2047306T3 (en) | 1994-02-16 |
| CN1023512C (en) | 1994-01-12 |
| ATE99044T1 (en) | 1994-01-15 |
| EP0435830A1 (en) | 1991-07-03 |
| IT8903784A0 (en) | 1989-12-22 |
| BR9006561A (en) | 1991-10-01 |
| DE69005432T2 (en) | 1994-04-14 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| EEER | Examination request | ||
| MKLA | Lapsed |