Method and device for producing a cartridge case

Abstract

The present invention relates to a method for producing a cartridge case by connecting the components thereof. The method comprises: providing a breech ring and a case made of the same or different materials; aligning the breech ring and the case in a device using positioning aids; providing a gap between the breech ring and the case; enclosing the region to be connected using an annular field former; conducting a current through the field former in order to induce currents in at least a first electrically conductive component, whereby a Lorentz force is generated; accelerating the first component away from the field former towards the second component to form an integral bond between the components.

Description

[0001] JECK, FLECK & PARTNER mbB P.O. Box 14 69 • D-71657 Vaihingen / Enz

[0002] PAT EN TA N WÄ LT E Telephone (07042) 9728 - 0

[0003] Fax (07042) 9728 - 11

[0004] A 25752-PCT - YY / YY August 18, 2025 Patrick Schmitz

[0005] Geislinger Weg 11 71732 Tamm

[0006] - 1 -

[0007] Method and apparatus for manufacturing a cartridge case

[0008] Description

[0009] The present invention relates to a method for manufacturing a cartridge case according to independent claim 1. Preferred embodiments are specified in the description and the dependent claims.

[0010] Traditionally, cartridge cases are manufactured by mechanically forming a single metal part made of brass, steel, or other alloys. This process requires numerous forming, annealing, and cleaning steps, which is time-consuming, space-consuming, and costly. The present invention differs from known methods, in particular, in that the cartridge case is manufactured from two separate components—a base and a sleeve—by means of kinetic acceleration towards one another and the resulting metallurgical bond upon contact of the components. In contrast to conventional welding processes, this enables the joining of dissimilar materials without significant heat input.

[0011] The method described in US10866073B2 for manufacturing multi-part sleeves uses thin sheets that are formed over a die. The present invention differs from this method in the use of prefabricated components and the metallurgical bond achieved by accelerating one component onto another.

[0012] In contrast to the electrical resistance welding using a roller electrode described in GB113601A, the present invention uses the Lorentz force generated by, for example, a magnetic pulse to create a material-bonded connection, in particular without heat input.

[0013] From DE 10 2013 100 930 B3, a method for manufacturing a cartridge case is known in which two different metallic materials are first axially joined over their entire surface to form a common workpiece, which is then formed into a finished cartridge case in several forming steps, in particular by extrusion. The materials are joined before forming, for example by roll cladding, casting, friction welding, capacitor discharge welding, or pulse magnetic welding. The resulting workpiece is then mechanically formed in several stages, including forming the case mouth, drilling a primer hole, creating an ejector groove, and removing excess material.

[0014] This well-known process therefore always requires upstream manufacturing and planar axial joining of the materials to form a solid initial workpiece, as well as subsequent multi-stage mechanical forming to complete the cartridge case. This results in additional manufacturing steps, longer process chains, and mechanical and thermal stresses that can lead to changes in the material structure, which can adversely affect the material reliability and pressure tightness under the extreme pressure conditions of a controlled explosion of the propellant charge in the finished cartridge.

[0015] The present invention provides for supplying the sleeve shell and the base piece as functionally complete individual components and joining them in the final manufacturing step by means of radial pulse magnetic welding, thus creating a material-locking connection without requiring any further forming operations at the joint. This eliminates the need to produce a solid, combined initial workpiece and the subsequent extensive forming process to create the finished sleeve. Furthermore, a specific joining geometry is unnecessary, as the joining gap is defined solely by the geometry and orientation of the components. The process allows for a material-conserving solid-state connection without significant heat input, thereby preserving the microstructure and achieving high strength and tightness in the joining area. Simultaneously, a high degree of freedom is achieved with regard to material combinations and component design.

[0016] From JP H04-319024 A, a method for manufacturing an elongated projectile core is known, in which several shorter elastic core elements are arranged in an elongated cylindrical metal body and axially compressed ("caulking") at both ends of the cylinder by electromagnetic forming. In this process, the end regions of the cylinder are individually processed in an electromagnetic forming machine with a coil arrangement, so that the applied magnetic field causes plastic compression of the end regions, thereby firmly clamping the core elements. Optionally, the core elements can consist of different shapes, such as solid cylinders and ring bodies, to achieve specific ballistic properties, e.g., for penetration ("immersion").The known process is particularly useful for the cost-effective production of projectile cores by using smaller starting materials and avoiding complex machining steps. A 25752-PCT - YY / YY - 4 - August 18, 2025.

[0017] This method involves manufacturing the projectile core as an assembly of several sub-cores within a metallic casing and fixing it solely by mechanical deformation of the casing ends using electromagnetic forces. A material-bonded connection in the joining area, particularly without plastic deformation of the entire casing structure, is not disclosed. Likewise, no method is described or suggested in which a finished case base is joined to a separate case jacket in a final manufacturing step in a pressure-resistant and gas-tight manner.

[0018] The present invention differs from JP H04-319024 A in particular in that

[0019] • no multiple shorter core elements are arranged in a shell structure,

[0020] • a joining process is used and not a forming process that is aimed at axial compression (“caulking”) of the end regions,

[0021] • instead, radial impulse magnetic welding is used to join the sleeve shell and base piece materially,

[0022] • The joining step is the last manufacturing step, without any subsequent forming operations being necessary at the joint of the workpiece parts,

[0023] • and the joining gap and positioning are defined by the geometry of the two finished components.

[0024] The method according to the invention allows for a heat- and shape-preserving connection, which prevents material stress corrosion and is particularly suitable for cartridge cases with high precision requirements.

[0025] From DE 20 2006 001 923 U1, a cartridge case for long gun ammunition is known in which a tubular case body is connected to a separate case head. The case head has higher strength values ​​than the brass material commonly used for cartridge cases, preferably through the use of an iron or steel material, in particular a corrosion-resistant steel. The case head is provided with a circumferential collar that encloses a firing chamber and is connected to the primer receptacle via a firing pin hole. The connection between the case head and the case body is made by brazing, with the case body being made of steel or brass tubing. The collar is intended to withstand high gas pressures and relieve stress at the connection point. The process includes not only the material processing of the sleeve base and sleeve body, but also chipless forming steps and the production of the brazed joint.However, it is known from practice that cartridge cases manufactured according to the method of DE 20 2006 001 923 U1 do not meet the high requirements for the resilience of the cartridge case as a whole and the joint in particular, insofar as the joint gives way to the conditions of the explosion in a statistically significant manner and the cartridge can burst open at the joint in an unfavorable and dangerous way for the user.

[0026] This process requires a thermal connection through brazing, which necessitates heating to temperatures around 1100°C. This can lead to structural changes and material weakening, and additional post-processing steps such as grinding the joint are required. Furthermore, the collared design and brazed joint require precise component fitting, making manufacturing complex.

[0027] The present invention differs from DE 20 2006 001 923 U1 in particular in that

[0028] • no brazing is used, but a material-bonded connection is made by radial pulse magnetic welding, the connection is made as the last manufacturing step between a finished sleeve shell and a finished base piece, A 25752-PCT - YY / YY - 6 - 18 August 2025 no significant heating of the components occurs, thus avoiding structural changes,

[0029] • no machining or forming post-processing of the joint is required,

[0030] • and the joining geometry does not have to be determined by a specific collar with a centering shoulder, but can be flexibly determined by the geometry of the two components, for example by the base and sleeve simply overlapping.

[0031] These features enable a shorter process chain, reduce the thermal and mechanical stress on the components, and allow a wider selection of material combinations while maintaining high strength and tightness in the joining area.

[0032] DE 10 2016 219 307 A1 describes in particular the joining of damper assemblies, for example between a chrome-plated steel piston rod and an aluminum end piece, whereby the process can also be used on coated or nitrided surfaces without damaging them.

[0033] The present invention relates to a method for manufacturing a cartridge case by joining a case shell to a base piece by means of radial pulsed magnetic welding, without requiring a stud-socket geometry with a defined gap width. Instead, the components are provided in their final shape and joined directly at the joint by electromagnetic pulse energy. Furthermore, no machining or forming post-processing of the joint is required after joining. DE 10 2016 219 307 A1 provides no indication of the application of this technique to the manufacture of a cartridge case or any suggestion to the person skilled in the art of the resulting advantages for the final product of the cartridge case and, in this context, is to be considered outside the field of expertise (A 25752-PCT - JJ / JJ - 7 - 18 August 2025), or at least unsuitable for leading the person skilled in the art to the solution according to the invention.

[0034] From DE 196 02 951 A1, a method for shaping workpieces is known in which the magnetic field of a current pulse acts on a ring or a tube made of electrically conductive material. By means of a defined pulse shape, rings and tube sections can be deformed with high dimensional accuracy and dimensional stability, and in particular can also be produced as plug connections.

[0035] The publication reveals several applications:

[0036] • Compressing tubes with magnetic coils so that the material penetrates ring grooves and a form-fit and force-fit connection is created.

[0037] • Expanding pipes using a support core to avoid unwanted shrinkage during the initial impulse phase.

[0038] • Adapting electrically poorly conductive materials such as steel by means of an additionally arranged, electrically highly conductive pressure ring, which first compresses the component and is then expanded and removed in the reverse direction of the magnetic field.

[0039] The method described in this publication relies on the plastic deformation of the components, using additional auxiliary elements such as a support core or pressure ring. The adaptation is based primarily on mechanical forming and not primarily on a material-bonded connection. For electrically poorly conductive materials, an additional electrically conductive element is mandatory, which must be removed after joining. The method thus requires additional components, several work steps, and design modifications (e.g., the introduction of annular grooves, design for pressure ring receptacles) and is not aimed at the material-bonded joining of components. DE 196 02 951 A1 provides no indication of the application of this technique to the manufacture of a cartridge case or any suggestion to the person skilled in the art regarding the resulting advantages for A 25752-PCT - JJ / JJ - 8 - 18.August 2025 the final product of the cartridge case and in this context is to be described as outside the field of expertise, or at least unsuitable to lead the person skilled in the art to the solution according to the invention.

[0040] The present invention enables the material-bonded joining of a sleeve shell to a base piece by means of radial pulse magnetic welding, without the need for extensive plastic deformation in conjunction with mechanical form-fitting. The components are provided in their intended geometry and are directly joined by the joining pulse, without any post-processing of the joint. Even minimal gaps between the workpieces are sufficient, which reduces the minimal shape adjustment in the joining area to a mere formality. This significantly reduces manufacturing effort and allows for much greater flexibility in material and geometry selection.

[0041] German patent application DE 10 2004 010 723 A1 discloses a method for attaching metallic components to a workpiece by electromagnetic forming. In this process, a first, electrically conductive component is radially formed and plastically deformed by means of a rapidly changing magnetic field, so that it is pressed against a second component. The connection is achieved essentially by mechanical positive locking. German patent application DE 6 describes, in particular, joining applications on rotationally symmetrical workpieces such as tubes, rings, or sleeves, which are radially deformed around their circumference to fit tightly against an internal component, such as a shaft or a solid core.

[0042] For poorly conductive materials, D6 specifies the use of an electrically conductive adapter body, which is first radially accelerated by the magnetic field and then mechanically presses the joining partner against it.

[0043] Disadvantages of the known solution

[0044] The methods disclosed in D6 always require plastic deformation of one of the joining partners to create the positive fit. A purely material-bonded A 25752-PCT - JJ / JJ - 9 - 18 August 2025

[0045] Joining by pulsed magnetic welding without macroscopic deformation is not described. Furthermore, the joining process does not occur between two finished end components as the final manufacturing step, but requires an adapted geometry (e.g., the introduction of grooves or interference fits) and, if necessary, additional auxiliary elements such as adapter rings. DE 10 2004 010 723 A1 provides no indication of the application of this technique to the manufacture of a cartridge case or any suggestion to those skilled in the art regarding the resulting advantages for the final cartridge case product and, in this context, is to be considered outside the field of expertise, or at least unsuitable for leading those skilled in the art to the solution according to the invention.

[0046] Differences of the present invention

[0047] The present invention differs from DE 10 2004 010 723 A1 in particular in that

[0048] • no significant plastic deformation of the joining partners occurs,

[0049] • the connection is made exclusively by radial pulse magnetic welding, whereby a metallurgical bond is created between the contact surfaces,

[0050] • the components - sleeve shell and base piece - are in their final geometry and no machining or forming post-processing of the joint is required after joining,

[0051] • and no additional conductive adapter bodies or auxiliary elements are needed, even if one joining partner is made of a poorly conductive material.

[0052] The invention thus provides a material-friendly, process-reliable joining method that is specifically tailored to the joining of precision-manufactured cartridge case components A 25752-PCT - JJ / JJ - 10 - 18 August 2025 and differs significantly from the purely forming-based joining methods described in D6.

[0053] DE 10 2016 110 397 A1 relates to the axial fastening of functional elements to workpieces using a magnetic pulse process. A functional element with a positioning section is placed onto a (typically plate-like) workpiece with a defined gap and accelerated axially relative to the workpiece by a magnetic pulse, so that a material-bonded connection is formed in the contact area. This document describes setting heads, dies, positioning and contact surfaces, variable gap geometries, and – depending on the design – a targeted local deformation of the workpiece. The teaching aims at the industrially appropriate attachment of fasteners (e.g., bolt-Z threaded elements) and the reproducibility of the connection on sheet metal and general components. A manufacturing technique for producing a cartridge case is not disclosed.

[0054] • No reference to the problem in the manufacture of cartridge cases. DE 10 2016 110 397 A1 addresses the fastening of functional elements; it lacks any teaching for the production of a cartridge case or a case-base assembly, as well as the advantages of applying the magnetic impulse method to solve the problem according to the invention (gas tightness, structure-preserving joining).

[0055] • DE 10 2016 110 397 A1 does not discuss either the extreme pressure peaks (several thousand bar) occurring in the area of ​​the joint during firing, nor the requirements for gas-tight, cyclically highly stressed 360° ring connections. The person skilled in the art (F42B) therefore lacks the incentive to use this teaching, which is unrelated to cartridge case manufacturing technology (B23K).

[0056] • Local form adaptation instead of annular high-pressure seal: The printing process uses locally defined deformation / gap contour (including the type head / die). A circumferential, end-geometric cylindrical overlap joint between the sleeve shell and

[0057] Differences of the invention compared to DE 10 2016 110 397 A1 A 25752-PCT - JJ / JJ - 11 - 18 August 2025

[0058] • Purpose / Functional objective: To manufacture a cartridge case with a gas-tight, high-strength, circumferential connection between the case jacket and the base, designed for pressure loads during firing.

[0059] • Method: Radial pulse magnetic welding as a solid-state joining process on two end-geometric components; the joining step is sleeve-forming and the last manufacturing step in the joining area, without the need for post-forming / technical rework at the joining point.

[0060] German patent DE 10 2007 034 396 A1 discloses an electromagnetic forming device with a divisible multi-winding coil for forming tubular workpieces, in particular tube-to-flange connections, with optimized air gap, contact, and system efficiency. It does not deal with a thermally neutral joining technique and makes no reference to ammunition / cartridge joining; it describes a forming process, not a joining technique, and therefore does not provide a suggestion for the solution according to the invention. The present invention thus offers a simplified manufacturing process for cartridge cases that enables the combination of different materials and produces a high-strength joint without impairing the material properties, creating a particularly reliable gas-tight joint that requires no post-processing.

[0061] According to one aspect of the present invention, a method for manufacturing a cartridge case by joining its components is provided. The method may include providing two components, in particular a base and a case. The base and the case may be made of the same or different materials. The method may further include aligning the base and the case in a device using positioning aids. A gap may be provided between the base and the case. The area to be joined may be enclosed by an annular field former. The method may further include passing a high current through the field former to ensure high A 25752-PCT - YY / YY - 12 - August 18, 2025

[0062] The aim is to induce currents in a first electrically conductive component, i.e., the sleeve or the base piece, thereby generating a Lorentz force. This allows the first component to be accelerated away from the field former towards the second component, forming a material-bonded connection between the components.

[0063] According to a further aspect of the present invention, the base and the case can be made of different materials, selected from the group comprising steel, brass, titanium, aluminum, and other non-ferrous alloys. This can allow for optimization of the material properties for different areas of the cartridge case, such as hardness at the base and ductility at the case mouth. The component to be accelerated should be selected such that a Lorentz force can be exerted on it by the rifling.

[0064] According to another aspect of the present disclosure, the base and the sleeve can be prefabricated using different manufacturing processes. This can enable flexible manufacturing, whereby, for example, the base can be produced by machining and / or the sleeve by deep drawing.

[0065] According to another aspect of the present disclosure, the positioning aids may comprise a plastic holder or a gripper on a robot arm. Alternative positioning aids may be mechanical clamping devices or magnetic holders.

[0066] According to another aspect of the present disclosure, the current frequency and current intensity used in the magnetic pulse method can be approximately 15 kHz and 250 kA. These parameters can be adjusted depending on the material and geometry of the components to be joined, with the frequency ranging from 1 to 100 kHz and the current intensity ranging from 10 to 1000 kA. A 25752-PCT - YY / YY - 13 - August 18, 2025

[0067] According to another aspect of the present disclosure, the gap between the base piece and the sleeve can be created by the geometry and orientation of the components relative to each other. Alternatively, the gap can be created by additional spacers or adjustable positioning elements in the device.

[0068] According to another aspect of the present disclosure, the process may further include applying a coating to at least one of the components, base piece or sleeve, before or after the joining process in order to improve corrosion protection. The coating may consist of various materials, such as nickel, chromium, polymers, or oxide layers.

[0069] According to another aspect of the present disclosure, a device for manufacturing a cartridge case is provided. The device may include a mechanism that can be configured to align a base and a case within one another at a radial distance. The device may further include positioning aids that can be configured to assist in aligning the base and the case within the device. An annular field former may be included in the device, which may be configured to enclose an area to be joined. The device may further include, or be connected to, a power source that can be configured to conduct a current through the field former. A control unit may be included in the device, which can be configured to control the joining process for joining the base and the case to form a material joint.

[0070] According to a further aspect of the present invention, the positioning aids can comprise at least one (plastic) holder, a clamping device, or a gripper on a robot arm. Alternative positioning aids can be optical sensors or laser systems for the precise alignment of the components. A 25752-PCT - YY / YY - 14 - August 18, 2025

[0071] According to another aspect of the present disclosure, the current source can be configured to generate a current with a frequency of approximately 15 kHz and a current intensity of approximately 250 kA. The current source can be adapted to generate different frequencies and current intensities, depending on the specific requirements of the materials to be joined.

[0072] According to another aspect of the present disclosure, the device may further comprise a coating application unit which may be configured to apply a coating to at least one of the parts, base piece or sleeve, before or after the joining process. The coating application unit may employ various coating technologies, such as spray coating, electroplating, or plasma deposition.

[0073] FIG. 1 shows a sectional view of a cartridge case assembly and an electromagnetic field former, according to aspects of the present invention.

[0074] The present invention relates to a method for manufacturing cartridge cases by metallurgical bonding of separate components. This method can offer a multitude of advantages, particularly with regard to the flexibility of material selection and the quality of the resulting bond.

[0075] In some embodiments, the method may involve the use of two components, in particular a base and a case, which may be made of the same or different materials. This flexibility in material selection can make it possible to optimize the material properties for different areas of the cartridge case, such as hardness at the base and ductility at the case mouth.

[0076] In some embodiments, the method may involve aligning the base and sleeve in a fixture using positioning aids. This can enable precise alignment of the components, resulting in a high-quality connection. A 25752-PCT - YY / YY - 15 - August 18, 2025

[0077] In some embodiments, the method may involve passing a current through an annular field former to induce (high) currents in a first electrically conductive component. This can generate a Lorentz force that accelerates the first component away from the field former towards the second component, potentially forming a material-bonded connection between the components.

[0078] In some embodiments, the method may further include applying a coating to at least one of the components, base piece or sleeve, before or after the joining process to improve corrosion protection.

[0079] Overall, the presented method for manufacturing cartridge cases or parts thereof using the method according to the invention can offer improved flexibility in material selection, high quality of the compound produced and improved corrosion resistance.

[0080] Referring to FIG. 1, this figure shows a sectional view of a cartridge case assembly and an (electro)magnetic field former. The assembly comprises a base piece 1 and a sleeve 2, positioned for connection. An annular field former 3 is shown, enclosing the area where the base piece 1 and the sleeve 2 are to be joined.

[0081] In some embodiments, the base piece 1 and the sleeve 2 can be made of the same or different materials. For example, the base piece 1 can be made of steel and the sleeve 2 of brass, titanium, aluminum, or other non-ferrous alloys. In other embodiments, both the base piece 1 and the sleeve 2 can be made of the same material, for example, steel or brass.

[0082] The base piece 1 and the sleeve 2 can be aligned in a fixture using positioning aids. These positioning aids can, for example, include a plastic holder or a gripper on a robot arm. In some embodiments, the fixture can be configured to hold the base piece 1 and the sleeve 2 in a specific orientation to ensure optimal connection.

[0083] A gap can be provided between the base piece 1 and the sleeve 2. This gap can serve as an acceleration path for the joining process between the base piece 1 and the sleeve 2, which promotes a particularly durable connection of the components. In some embodiments, the gap can be created by the geometry and orientation of the base piece 1 and the sleeve 2 relative to each other. In other embodiments, the gap can be created by additional spacers or adjustable positioning elements in the device.

[0084] With reference to FIG. 1, the method is further described. The annular field former / electrically conductive coil / magnetic coil 3 can be configured to enclose a region of the cartridge case parts to be joined. In some embodiments, the field former 3 can conduct a (high) current to induce high currents in a first electrically conductive component. This is intended to generate a Lorentz force that accelerates the first component away from the field former 3 towards the second component, thereby forming a material-locked / compounded connection between the components.

[0085] In some embodiments, the first component can be the base piece 1 or the sleeve 2. The choice of which component is accelerated may depend on the specific material properties and the requirements of the connection. For example, in some cases the base piece 1 can be accelerated if it is made of a material with high electrical conductivity and ductility, while in other cases the sleeve 2 can be accelerated.

[0086] In principle, it is also conceivable that both components are accelerated towards each other. The use of a second field former may be advantageous in this regard, with the cartridge case components being positioned between the first and second field formers.

[0087] In some embodiments, the inner part, for example the base piece 1 (Fig. 1), can be supported by a mandrel to prevent unwanted deformation. This can be particularly important if the base piece 1 or the sleeve 2 is made of a soft or ductile material that could easily deform during the joining process.

[0088] In some embodiments, the device for manufacturing a cartridge case may include a feature configured to align the base piece 1 and the case 2 at a radial distance from each other. This can enable precise alignment of the components, resulting in a high-quality and stable connection. The device may further include positioning aids configured to assist in aligning the base piece 1 and the case 2 within the device. These positioning aids may, for example, include a plastic holder or a gripper on a robot arm. In other embodiments, the positioning aids may be mechanical clamping devices or magnetic holders.

[0089] The acceleration of the first component can be adjusted to such a high degree that the oxide layer on both the first and second components is removed. This enables a metallurgical bond between the components within a very short time, for example, approximately 25 ps. In some embodiments, the resulting joint can be annular and have a width of a few millimeters. The width of the joint can be increased as required, particularly by adjusting the field dimensions and / or the degree of overlap of the sleeve parts to be joined.

[0090] In some embodiments, the cartridge case, through the kinetic energy of the case part(s) discharged in the material bond, does not experience any significant temperature increase during the joining process and can be removed from the device. Therefore, no thermally induced changes in the material properties occur during the process, as there is essentially no effect on the microstructure.

[0091] In some embodiments, the current frequency used in the inventive method can be in the range of 15 kHz and the current intensity can be in the range of 250 kA. In other embodiments, the current frequency and the current intensity can be adjusted depending on the material and geometry of the components to be joined. For example, the frequency can be between 1 and 100 kHz and the current intensity between 10 and 1000 kA, and is selected depending on the materials and the wall thickness of the cartridge case parts so that the accelerating Lorentz force provides a metallurgical bond. As a guideline, a velocity of approximately 200 m / s for the accelerating part at the moment of impact on the other component can be assumed. However, it should be noted that the velocity required for a metallurgical bond can be material-dependent.The speed information provided should therefore be understood as an illustration of the expected order of magnitude or guideline value and does not constitute a fixed value.

[0092] It should be noted that the descriptions in this text are merely exemplary and are not to be understood as limiting. All features from all embodiments can be interchanged or combined with one another, and each feature of each embodiment is disclosed independently of all other features of each individual embodiment.

[0093] In some embodiments, the device for manufacturing a cartridge case may include or be connected to a power source configured to conduct a (high) current through the field former 3. The power source may be capable of generating a current with a frequency of about 15 kHz and a current of about 250 kA. In other embodiments, the power source may be adjustable to generate different frequencies and currents, depending on the specific requirements of the materials to be joined. For example, the frequency may range from 1 to 100 kHz and the current from 10 to 1000 kA.

[0094] The device may further include a control unit configured to control the joining process for connecting the base piece 1 and the sleeve 2 to form a material connection. The control unit may be capable of controlling the current flow through the field former 3, monitoring and, if necessary, adjusting the positioning of the components, and monitoring and controlling the joining process as a whole.

[0095] The positioning aids can include a plastic holder or a gripper on a robot arm. These can serve to precisely align the base piece 1 and the sleeve 2 in the device and to hold them in position during the joining process. In other embodiments, the positioning aids can be mechanical clamping devices or magnetic holders.

[0096] The sleeve 2 advantageously has good electrical conductivity. This can help ensure that the currents induced by the field former 3 flow effectively in the sleeve 2 and generate a sufficient Lorentz force to accelerate the sleeve 2 towards the base piece 1.

[0097] The resulting joint can be ring-shaped and several millimeters wide. This can help to create a robust and tight connection between the base piece 1 and the sleeve 2. In other embodiments, the width of the joint can be adjusted, for example, by adjusting the dimensions of the field former 3 or the overlap of the parts to be joined.

[0098] In some embodiments, the base 1 and the sleeve 2 can be prefabricated before being positioned and joined in the device. Prefabrication can be achieved using various manufacturing processes. For example, the base 1 can be machined and the sleeve 2 deep-drawn. In other embodiments, the base 1 and the sleeve 2 can be manufactured by other suitable methods, such as casting, forging, or extrusion. The choice of manufacturing method may depend on the specific requirements for the components and the materials used.

[0099] In some embodiments, the method may include applying a coating to at least one of the components, base piece 1 or sleeve 2, before or after the joining process to improve corrosion protection. The coating may consist of various materials, such as nickel, chromium, polymers, or oxide layers. In other embodiments, the coating may also consist of other suitable materials that provide good corrosion protection. The coating may be applied, for example, by spray coating, electroplating, or plasma deposition. In some cases, the coating may also be applied by other suitable methods, such as dip coating or electrochemical deposition.

[0100] The device for manufacturing a cartridge case may, in some embodiments, include a coating application unit configured to apply a coating to at least one of the parts, base piece 1 or case 2, before or after the joining process. The coating application unit may employ various coating technologies, such as spray coating, electroplating, or plasma deposition. In other embodiments, the coating application unit may also employ other suitable coating technologies, such as dip coating or electrochemical deposition. The coating application unit may be configured to apply the coating uniformly and in a controlled thickness to the components to ensure optimal corrosion protection. A 25752-PCT - YY / YY - 21 - August 18, 2025

[0101] The inventive method can be carried out as follows: a) Providing a cylindrical, open-ended cartridge case, e.g., made of brass, and a base piece, e.g., made of steel, e.g., with a finished primer pocket and primer hole; b) Aligning the components in a device to form a circumferential radial gap defined by the component geometry of e.g.0.2 mm to 0.5 mm; c) Enclosing the joining area with an electrically conductive coil, in particular with an annular field former; d) Applying a current pulse of 10 kA to 1000 kA to the coil at a frequency of 1 kHz to 100 kHz, so that the sleeve shell is accelerated radially at a speed of preferably at least 200 m / s towards the base piece; e) Material-fit joining without melting the material, wherein no forming or heating takes place outside the joining area and the joining step is the last manufacturing step in the joining area.

Claims

A 25752-PCT - YY / YY - 22 - 18 August 2025 Claims 1. Method for manufacturing a cartridge case by joining its components, namely a base piece (1) and a case jacket open at both ends (2), the method comprising: Providing both components, wherein the base (1) and the sleeve (2) are made of the same or different materials; Aligning the base piece (1 ) and the sleeve shell (2) in a device forming a circumferential radial gap between the base piece (1 ) and the sleeve (2) in an overlapping section of the two components (1 , 2) in which the connection of the components is provided; Enclosing the section of the two components (1 , 2) to be joined with an electrically conductive coil (3), in particular with a ring-shaped field former; Generating a time-limited magnetic pulse by means of the coil, whereby eddy currents are induced in at least one of the components and a Lorentz force radial to the longitudinal axis of the sleeve is generated in order to accelerate the respective component away from the field former and onto the other component and to materially bond the components (1 , 2) together without melting the material, wherein the joining step is the cartridge case forming step and represents the final manufacturing step for the production of the cartridge case in the overlapping joining section.

2. The method according to claim 1, wherein the base and the sleeve are made of different materials selected from the group comprising steel, brass, titanium, aluminium and other non-ferrous alloys. A 25752-PCT - YY / YY - 23 - 18 August 2025 3. The method according to claim 1 or 2, wherein the base and the sleeve are prefabricated using different manufacturing processes.

4. The method according to any one of claims 1 to 3, wherein the positioning aids comprise a plastic holder or a gripper on a robot arm.

5. The method according to any one of claims 1 to 4, wherein the current frequency and current strength used during connection are approximately 15 kHz and 250 kA.

6. The method according to any one of claims 1 to 5, wherein the gap between the base piece and the sleeve is created by the geometry and orientation of the components relative to each other.

7. The method according to any one of claims 1 to 6, further comprising the application of a coating to at least one of the components, base piece or sleeve, before or after the joining process to improve corrosion protection.

8. The method according to any one of claims 1 to 7, wherein the axial overlap between the sleeve shell and the base piece is at least 1.5 times the wall thickness of the sleeve shell.

9. The method according to any one of claims 1 to 8, wherein the bottom piece is flat in the connection area to the sleeve and has no depressions or grooves.

10. The method according to any one of claims 1 to 9, wherein no machining or forming post-processing is carried out at the joining point after joining.

11. The method according to any one of claims 1 to 10, wherein the acceleration of the moving component is selected such that oxide layers at the joining areas are completely broken up, A 25752-PCT - YY / YY - 24 - 18 August 2025 12. A device for manufacturing a cartridge case, the device comprising: a device configured to align a base piece and a case within each other at a radial distance; Positioning aids configured to assist in aligning the base and sleeve in the device; An electrically conductive coil, in particular with an annular field former, configured to enclose a section to be joined; a power source configured to pass a high current through the coil; and a control unit configured to control the joining process to join the base piece and the sleeve to form a material joint.

13. The device according to claim 12, wherein the positioning aids comprise at least a plastic holder, a clamping device or a gripper on a robot arm.

14. The device according to one of claims 12 or 13, wherein the power source is configured to generate a current with a frequency of approximately 15 kHz and a current intensity of approximately 250 kA.

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