Woven insert

Abstract

To provide an insert which is handled safely and needs only a thin jacket wall.SOLUTION: A fabric insert to be received in a jacket wall of an ammunition cartridge (6) in a cylinder shape made of a combustible felt fiber material is provided, wherein a fabric comprises one or a plurality of threads forming a plurality of mesh rows (18.1-18.3) each of which includes a plurality of meshes (19, 20.1-20.3, 21) extending in a circumferential direction (U) of the insert along a longitudinal direction (L) of the insert.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to an insert made of a woven fabric intended to be received in a jacket wall of a cylindrical cartridge made of a combustible felt fiber material. [Background technology]

[0002] Cartridges have long been known as an element of firearm ammunition. They are used to hold propellant powder, usually in granular form. Cartridges usually have a cylindrical, elongated, hollow shape. The cylinder wall of a cartridge is referred to herein as the jacket wall.

[0003] Flammable cartridges are burned or consumed as a result of combustion. If this occurs sufficiently without residue, there is no need to remove the cartridge residue before the next shot. Ideally, only the metal base attached to the outside of the cartridge needs to be removed.

[0004] Usually, combustible cartridges are known to be produced from nitrocellulose and cellulose, using additives such as binder resins and stabilizers. To produce them, a screen mould is immersed vertically or horizontally into an aqueous pulp containing nitrocellulose and cellulose. With the help of negative pressure, the screen mould sucks the fibrous pulp. A wet fleece, usually called "green felt", is formed, which constitutes the preliminary stage of the jacket wall. To achieve the final shape of the jacket wall and to dehydrate it, the fleece / green felt is pressed and heated, at least temporarily, which dimensionally stabilizes the cartridge. Summary of the Invention

[0005] Nevertheless, due to the nature of the flammable material, the cartridges are fragile. If they fall to the ground or hit a solid object during handling, the jacket wall may crack or the cartridge may break completely. If the cartridge is filled with propellant powder as intended, this is no longer acceptable, as the escape of propellant powder clearly represents a major safety risk.

[0006] For this reason, for a long time, various proposals have been made to reinforce the cartridge jacket wall with embedded inserts and thus reduce its vulnerability to destruction. For example, it is known from WO 2011 / 015346 A1 that a coarse mesh made of cotton threads is wrapped in the jacket wall, created during the manufacture of the pulp. The multi-layered wrapped net increases the strength of the cartridge to such an extent that the formation of cracks in the jacket wall or even the complete destruction of the cartridge by impact or fall is practically impossible. However, the manufacturing process is expensive, the thickness of the jacket wall is large, and for a certain outer diameter, the volume of the cartridge available for the absorption of propellant powder is smaller than would be possible in the absence of the multi-layered reinforcing insert.

[0007] Against this background, it is an object of the present invention to provide an improved insert which is safe to handle and which nevertheless requires only a relatively thin jacket wall.

[0008] This object is achieved by an insert having the features of claim 1. Advantageous embodiments are the subject of the dependent claims and the following description.

[0009] According to one embodiment, an insert made of a woven fabric is proposed to be received in the jacket wall of a cylindrical cartridge made of a combustible felted fibrous material, the woven fabric being formed as a knitwear, and therefore in particular comprising one, several or several threads along the longitudinal direction of the insert forming a number of mesh rows, each of which comprises a number of meshes extending in the circumferential direction of the insert.

[0010] The textile is a knitwear made of yarns of natural fibers and blended yarns of natural fibers and plastics. Preferably, the textile has only one layer. According to one embodiment, the insert made of knitwear consists of knitted, woven and / or crocheted fabric.

[0011] According to one embodiment, the natural fiber is cotton, due to its high tear strength. According to one embodiment, the plastic material is or includes polyurethane, due to its high elasticity.

[0012] In order to obtain a suitable combination of tear strength and stretchability, according to one embodiment the natural fibre yarns have a proportion, in particular a yarn content and / or weight content, of 30% to 50% in the woven fabric and / or the blended natural fibre / plastic yarns have a proportion, in particular a yarn content and / or weight content, of 50% to 70% in the woven fabric, in particular a ratio of 50 to 50.

[0013] In order to precisely adjust the stretchability, according to one embodiment the blended yarn of natural fibres and plastic has a natural fibre content of 70% to 95%, in particular between 70% and 95%, and / or a plastic fibre content of 5% to 30%, in particular between 5% and 30%. In particular the share is 89 to 11.

[0014] According to one embodiment, the insert constitutes a hose having a diameter in the unstretched state of 40 mm to 155 mm, in particular between 40 mm and 155 mm, in order to expand to typical cartridge diameters with low elongation. In particular, the hose is manufactured without seams, for example on a circular knitting machine.

[0015] In order to ensure a high tear strength of the insert, according to one embodiment, the mutually associated meshes of adjacent mesh rows are respectively guided on the same radial side of the hose of the insert and / or, in principle, adjacent meshes of one mesh row are guided on different radial sides.

[0016] In order to ensure that the typical shape of the propellant powder in the cartridge is retained in the event of breakage, the fabric according to one embodiment has a mesh row density of 10 to 13, in particular between 10 and 13, mesh rows per cm and / or a rib or mesh density of 10.5 to 13.5, in particular between 10.5 and 13.5 meshes or ridges per cm.

[0017] According to one embodiment, the insert is stretchable. According to one embodiment, the insert is formed of one layer and is stretchable both axially and radially.

[0018] Preferably, the fabric has a maximum stretch / elasticity of about 420% in the circumferential direction of the hose and about 80% in the longitudinal direction of the hose. These stretch / elasticity values ​​ensure containment of the propellant powder even in the event of a typical cartridge failure.

[0019] According to one embodiment, it is provided to embed an expandable insert in the cartridge jacket wall. This is in contrast to the previous tradition of increasing the strength of the cartridge jacket wall by means of an insert. According to the invention, mechanical damage to the cartridge jacket wall is tolerated, and the insert has the function of being able to keep the crack and break openings in the cartridge jacket wall closed against the escape of the propellant powder, due to its expandability. This allows the cartridge jacket wall to be thinned in two ways. It can be assumed that the mechanical strength that the cartridge jacket wall has from the beginning without considering the insert is less than before, since cracks and breaks are tolerated. Also, the insert itself can be made relatively thin, since it does not reinforce the cartridge jacket wall, but only holds the bulk powder in the cartridge.

[0020] The elasticity of the insert must be dimensioned to be able to perform this function, i.e. to bridge cracks or other gaps by expansion, without reaching the elongation at break. The correct elongation / elasticity parameters in this sense can be empirically determined, for example, by standardized drop tests, which have been used so far to test the breaking strength of known cartridges. Tests already carried out by the applicant with cartridges according to embodiments of the invention have shown that sufficient elasticity of the insert in the longitudinal direction of the cartridge may be more important than extensibility in the circumferential direction.

[0021] The elasticity of the insert is achieved by forming it as a knitwear, very preferably as a woven, knitted and / or crocheted fabric, where the stretchability is the result of the guidance of the yarn.

[0022] Of course, the insert must also be combustible, so it is usually made of cotton thread, which, however, is not elastic in itself. If the thread itself should also contribute to elasticity, the cotton thread is completely or partially replaced by a polyurethane-cotton blend. Such a blend is commercially available. It has a polyurethane core covered with regular cotton.

[0023] In order to keep the thickness of the jacket wall small, an insert consisting of only one layer of knitwear is preferred. The single-layer form has been found to be sufficient to safely prevent the escape of bulk powder through cracks and other crevices in the jacket wall.

[0024] Based on empirical knowledge, it is optimal to place the insert in the center of the jacket wall based on the wall thickness of the jacket wall, although it is also possible to place the insert in a wall area further inward without significantly compromising the retention function. Such placement may be a result of manufacturing.

[0025] In a preferred embodiment for all shapes of insert, the insert is configured as an expandable hose whose central axis coincides with the central axis of the embedded cartridge. The hose is preferably manufactured without seams. Suitable expandable hoses are industrially manufactured and commercially available as knitwear, in particular as woven, crocheted and / or knitted fabrics.

[0026] The use of tubular inserts greatly simplifies the manufacture of ammunition cartridges according to the invention. During the above-mentioned manufacturing process, after the green felt is built up, the expandable single-layer hose is expanded, for example, to the wall thickness in the middle of the wall and pulled axially on the screen mold over the green felt built up to this extent. The green felt is then further built up until it reaches its final thickness, after which it is compressed as usual and hardened by heating.

[0027] In order to achieve the thinnest possible insert in the radial direction and increase the space for the propellant powder at a certain diameter, according to one embodiment the insert is of single layer type and can be stretched both axially and radially. In one type of insert, the fabric must be biaxially stretchable to accommodate cracks / breaks etc. in the cartridge and allow axial and / or radial (also meaning circumferential) expansion.

[0028] According to one embodiment, the insert has at least two or three layers, a first layer of which is stretchable at least axially and a second layer of which is stretchable at least radially, such that less expensive fabrics can be used and each fabric only needs to be stretchable about one axis.

[0029] In this case, in particular the radial elasticity of the insert is understood as the elasticity of the insert relative to its circumferential direction, in particular if the insert is tubular or of another hollow shape, in particular cylindrical or partially cylindrical. The correspondence of the two terms is due in particular to the application of tubular inserts. If the hose is stretched in the radial direction, this elasticity is provided in particular by stretching the insert relative to its circumferential direction.

[0030] Depending on the materials used, and possibly on processing the materials into a suitable knitwear, the inserts according to various embodiments can be stretchable due to the macroscopic elasticity of the insert's material and / or due to the meshing of the insert's knitwear.

[0031] As regards the choice of material for the insert, tests have shown that the insert suitably comprises at least one natural and / or plastic thread, in particular cotton thread and / or polyurethane and cotton blend thread and / or silk thread and / or polyurethane thread and / or nylon thread, in particular consisting of at least one such thread.

[0032] According to one embodiment, the insert is arranged in the middle of the jacket wall or closer to the inside or outside of the jacket wall with respect to its thickness, one arrangement of the insert in particular is provided between 1 / 4 and 4 / 4 of the jacket wall thickness. Tests carried out by the applicant have shown that in the event of damage, the retention of the propellant powder is ensured by arranging the insert between 1 / 3 and 2 / 3 of the jacket wall thickness. This is possible both in the middle arrangement and between 2 / 3 and 3 / 3 of the jacket wall thickness.

[0033] To further simplify the manufacturing process, according to one embodiment, the insert can also be placed directly on the inside of the jacket wall. The felt of the cartridge on the screen then does not have to be interrupted to install the insert. Rather, the insert is first installed and only then the creation of the felt begins. In this manufacturing variant, the insert is reliably and securely placed in the finished cartridge, especially since the cartridge material is deposited between the meshes of the insert.

[0034] In this case, a cylindrical cartridge is also understood to be a cartridge which is cylindrically formed in an essential part of its longitudinal extension, but has a different, in particular tapered, diameter towards its base and / or its tip.

[0035] Further advantages and possible applications of the invention can be gleaned from the following description in conjunction with the drawings. [Brief description of the drawings]

[0036] [Figure 1] FIG. 1 shows a schematic diagram of a cartridge including an insert as part of a cartridge according to an exemplary embodiment of the present invention; [Diagram 2] Photograph of the cartridge in Figure 1 after destructive testing with the insert partially exposed in the fracture area. [Diagram 3] FIG. 3 is a schematic cross-section of a knitted fabric forming the insert of the cartridge of FIGS. 1 and 2; DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0037] As an exemplary embodiment, Figure 1 shows a schematic of a cartridge 6 as part of a cartridge 1. The cartridge has an elongated cylindrical shape and contains granular propellant powder 4. An insert 5 according to an embodiment of the invention is embedded in the jacket wall of the cartridge 6. A brass base 2 is attached to the lower end of the cartridge 1 together with a detonator 3.

[0038] The cartridge 6 is formed of felted cellulose and nitrocellulose fibers and conventional additives. The embedded insert 5 is a seamless elastic hose made from knitwear 12, here by way of example a woven, crocheted and / or knitted fabric. It is embedded in the cartridge 6 as shown so that its central axis coincides with the central axis of the cartridge.

[0039] The hose is made of 50% regular cotton yarn and 50% polyurethane-cotton blend yarn, and experiments have shown that the variants of 1 / 3 cotton yarn and 2 / 3 polyurethane-cotton blend yarn are also suitable materials for the hose. In both cases, the blend yarn has a polyurethane core covered with cotton. In an exemplary embodiment, the blend yarn has a composition of 89% cotton and 11% PUR, and according to different embodiments, PUR contents of 5% to 20%, in particular between 5% and 20%, are possible.

[0040] Being formed as knitwear 12, the hose forming the insert is very elastic. The axial elasticity of the cartridge is further supported by the polyurethane / cotton blend yarn.

[0041] If the cartridge 6 is damaged by mechanical action such that a crack, gap or other breakage opening appears in the jacket wall, the insert will be exposed at the breakage opening and will be stretched there without being torn to such an extent that it will keep the breakage opening closed against the granular propellant powder inside the cartridge.

[0042] A typical cartridge according to the invention has an outer diameter of 50 to 170 mm, in particular between 50 and 170 mm, a length of 35 to 75 cm, in particular between 35 and 75 cm, a wall thickness, in particular the jacket wall thickness, of 1.5 to 4 mm, in particular 2.5 mm. When the cartridge is manufactured, the insert is attached with a slight elongation of about 10% and in the unstretched state, the diameter is 40 to 155 mm, in particular between 40 and 155 mm.

[0043] Figure 2 shows a photograph of the cartridge of Figure 1 after a destructive test in which the insert 5 is partially exposed in the destruction zone 8. The arrangement of the insert 5 between the radially inner part 6a and the radially outer part 6b of the cartridge 6 is clearly visible. The felt 10 formed by the mesh of the insert 5 is also partially visible.

[0044] The black lettering on the outer part 6b of the cartridge 6 comes from the sample designation of the destructive tests carried out and is not relevant here.

[0045] FIG. 3 shows diagrammatically a cut-out from the knitwear 12 forming the hose of the insert 5 of the cartridge 6 of FIGS.

[0046] Tests carried out by the applicant have shown that the insert 5 as knitwear 12, in particular as woven, crocheted and / or knitted fabric, provides very high tensile strength and high elongation values ​​at a relatively low weight per area and small radial dimensions of the hose. Such a woven surface is produced, for example, on a circular knitting machine. For example, a circular knitting machine can be used to produce a seamless tubular insert as shown in the exemplary embodiment.

[0047] A particular mesh weave 14 is used in the exemplary embodiment to allow for very high stretch of the insert 5. A weave diagram 16 of this mesh weave 14 is shown in FIG.

[0048] The weaving diagram 16 partially illustrates a number of mesh rows 18 arranged vertically one above the other in Fig. 3 and a number of ridges 20 arranged horizontally in Fig. 3. In an exemplary embodiment, the vertical direction in Fig. 3 corresponds to the longitudinal direction L of the insert 5 or cartridge 6. The horizontal direction corresponds to the circumferential direction U of the insert 5 or cartridge 6.

[0049] At its lower end, each mesh 20.2 is guided through a corresponding mesh 20.3 of the adjacent lower mesh row 18.3 and guides a corresponding mesh 20.1 of the adjacent upper mesh row 18.1.

[0050] The corresponding inter-associated meshes 20 of adjacent mesh rows 18 form ridges 23, each guided on the same radial side of the hose of the insert, ie all outward or all inward.

[0051] Adjacent meshes 20 of the mesh row 18 are always guided in opposite radial directions, i.e. if one adjacent mesh 20 is guided inwards, the adjacent meshes 19, 21 are respectively guided outwards, and if one adjacent mesh is guided inwards, the adjacent meshes are respectively guided inwards.

[0052] In an exemplary embodiment of the cartridge, in the unstretched state of the insert in the mesh, 10 to 13, in particular between 10 and 13, mesh rows are provided in the knitwear, in particular between 11.5 to 12, in particular between 11.5 and 12, mesh rows (number of mesh rows MRZ, FIG. 3 shows the reciprocal) per cm of longitudinal extension. It is also customary to specify mesh rows per 2 centimeters. In this case, the insert has a weave pattern of 20 to 26, in particular between 20 and 26, in particular between 23 to 24, in particular between 23 and 24, mesh rows per 2 centimeters of longitudinal extension.

[0053] With regard to the ridges 23, in the unstretched state of the insert, a weave pattern is provided with 10.5 to 13.5, in particular between 10.5 and 13.5, in particular between 11.75 and 12.25, in particular between 11.75 and 12.25 ridges per centimeter of circumferential extension (ridge number MSZ, FIG. 3 shows its reciprocal). The indication of ridges per two centimeters is also customary. In this case, the insert exhibits a weave pattern with 21 to 27, in particular between 21 and 27 ridges per two centimeters of circumferential extension, in particular with 23.5 to 24.5, in particular between 23.5 and 24.5 ridges per two centimeters.

[0054] The insert of the exemplary embodiment, when mounted in the cartridge, exhibits a fabric elongation of 5% to 20%, in particular about 11%, compared to the unstretched state, in particular in the circumferential direction U (or radial direction R) of the cartridge and / or in the longitudinal direction L of the cartridge. If a small additional elongation due to the displacement at the break point is ignored, this stretched state constitutes in particular the stretched state shown in FIG. 2 in terms of magnitude.

[0055] The seamless tubular insert 5 used in the example embodiment exhibits a maximum elongation in the transverse direction, i.e. in the circumferential direction U of the hose, of about 420% in the view of Fig. 3. The maximum elongation in the vertical direction, i.e. in the longitudinal direction L of the hose, of the view of Fig. 3, is about 80%. The maximum elongation in the radial direction of the hose of the insert 5 can be calculated from the unstretched hose diameter and the maximum elongation in the circumferential direction U of the hose, taking into account additional elongation in the longitudinal direction L, if necessary.

[0056] Suitable materials for the insert 5 are, for example, cellulose fibres used in pure form (100% cellulose fibres) or in fibre blends (for example cotton fibres with synthetic materials such as PUR).

[0057] By matching (by practical experts) the fiber thickness and the technological parameters of yarn and knitted product manufacturing, the desired felting quality of the cartridge (when felted through the insert) is achieved in accordance with the exemplary embodiment, i.e. it is ensured that the fiber mass is caught in the "mesh shank" of the fabric, preventing separation and splitting of the cartridge body. [Explanation of symbols]

[0058] 1 Cartridge 2 bottom 3 detonator 4. Propellant Powder 5 Insert 6 Ammunition 6a Inside the cartridge 6b Outside of cartridge 8 Destruction Area 10. Felt 12 Knitwear 14 Mesh weaving 16 Weaving Pattern 18 Mesh Column 19,20,21 Mesh 23 Ridge L Longitudinal axis / direction U Circumferential direction R Radial direction MRZ Number of mesh rows MSZ Number of ridges

Claims

1. A fabric insert (5) for receipt in the jacket wall of a cylindrical cartridge (6) made of combustible felt fiber material, the insert being suitable for containing granular propellant powder; The insert is characterized in that the fabric is stretchable and is a knitwear (12) made of natural fiber yarns and blended natural fiber and plastic yarns.

2. 2. The insert of claim 1, wherein the fabric comprises only one layer.

3. An insert according to claim 1 or 2, characterized in that the natural fibre is cotton.

4. An insert according to any one of claims 1 to 3, characterized in that the plastic is or comprises polyurethane.

5. 5. An insert according to claim 1 , characterized in that the natural fibre yarns have a proportion, in particular a yarn content and / or weight content, of 30% to 50% in the fabric and / or the natural fibre / plastic blended yarns have a proportion, in particular a yarn content and / or weight content, of 50% to 70%.

6. 6. The insert according to claim 5, characterized in that said ratio is 50 / 50.

7. 7. An insert according to any one of claims 1 to 6, characterized in that the blended natural fibre and plastic yarn has a natural fibre content of 70% to 95% and / or a plastic fibre content of 5% to 30%.

8. The insert described in claim 7, characterized in that the natural fiber and plastic blended yarn has a natural fiber content of 89% and a plastic fiber content of 11%.

9. The insert (5) according to any one of the preceding claims, characterized in that the insert (5), in particular the fabric, comprises a knitted, woven and / or crocheted fabric.

10. 10. Insert according to claim 9, characterized in that the insert (5) is formed as a hose.

11. 11. An insert according to claim 10, characterized in that the hose, in an unstretched state, has a diameter in the range of 40 mm to 155 mm.

12. 12. An insert according to claim 10 or 11, characterized in that the hose is manufactured without any seams.

13. 13. An insert according to any one of claims 10 to 12, characterized in that the mutually associated meshes (20) of adjacent mesh rows (18) are respectively guided on the same radial side of the hose of the insert.

14. An insert according to any one of claims 10 to 13, characterized in that, in the circumferential direction (U) of the hose, the fabric has a maximum elongation of about 420%.

15. An insert according to any one of claims 10 to 14, characterised in that in the longitudinal direction (L) of the hose, the fabric has a maximum elongation of about 80%.

16. 16. Insert according to any one of the preceding claims, characterized in that adjacent meshes (20) of one mesh row (18) are always guided on different radial sides.

17. 17. An insert according to any one of claims 1 to 16, characterized in that the fabric has a mesh row density (MRZ) in the range of 10 to 13 mesh rows per centimeter.

18. 18. An insert according to any one of the preceding claims, characterized in that the fabric has a rib density (MSZ) or mesh density in the range of 10.5 to 13.5 meshes or ribs per cm.

19. An insert according to any one of claims 1 to 18, characterized in that the insert (5) is made as a single layer and is stretchable both axially and radially.

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