Method for analyzing a case, cartridge chamber of a firearm, and firearm

Abstract

The invention relates to a method for analyzing a case (1) of a cartridge (3) fired with the aid of a cartridge chamber (2). The invention further relates to a cartridge chamber (2) of a firearm (6) and to a firearm (6) having such a cartridge chamber (2). A cartridge chamber (1) or an associated firearm (2) can be uniquely associated with at least parts of a cartridge (5) fired from the cartridge chamber (1), in particular by means of said firearm (2), in that the cartridge chamber (2) is designed to influence the flow behavior of the case (1) during the firing process in such a way that, after the firing process, a frequency spectrum (4), in particular a natural frequency spectrum, of the case (1) is formed according to an identification code (5). The case (1) is vibrated, and the vibrations of the case (1) are detected, the frequency spectrum (4), in particular the natural frequency spectrum, of the case (1) being determined from the detected vibrations and the identification code (5) being determined from the frequency spectrum (4).

Description

[0001] Methods for analyzing a cartridge case, chamber of a firearm and firearm

[0002] The invention relates to a method for analyzing a cartridge case fired using a cartridge chamber, a cartridge chamber of a firearm and a firearm with such a cartridge chamber.

[0003] From DE 10 2005 003 752 A1, a cartridge chamber and a device for the controlled ejection of a cartridge case from the chamber are known. A defined case extraction resistance can be achieved with the aid of the cartridge chamber. This resistance is created by a minimum seal on the case, which is achievable with the aid of the cartridge chamber when the cartridge is fired. For this purpose, at least one groove is provided in the cartridge chamber in the front area of ​​the case. The individual groove can be located around the entire inner circumference of the cartridge chamber housing or only in specific sections of the inner circumference. During the ejection process, the energy released during the firing process is utilized and converted into velocity when the case is released. However, tracing the cartridges or assigning at least parts of the cartridges to the firearm with which this ammunition was fired is not possible with this device.Especially in criminal investigations and forensic studies, this information about how the ammunition was fired is important, particularly since firearms are often registered and their owners are therefore known. Identical cartridges fired from identical firearms with identical chambers will exhibit similar, if not entirely detectable, differences even after firing.

[0004] The traceability of cartridges, such as small-caliber ammunition, has become a crucial issue in recent years within non-governmental organizations (NGOs), security organizations, and especially regulatory bodies. Cartridges are also referred to as ammunition in this document. Given the global proliferation of firearms, particularly small arms, and their ammunition, the question arises as to how this ammunition can be traced, for example, to uncover illegal trade flows and / or facilitate law enforcement. The problem is that small-caliber ammunition is currently unmarked, making tracing very difficult. NGOs and joint governmental organizations (GGOs) are therefore calling for technologies and, above all, legislation to increase the transparency and traceability of small-caliber ammunition. Illegal trade routes for small-caliber ammunition do exist.Some of the small-caliber ammunition that ends up in conflict zones and in the hands of criminal organizations originates from illegal sources. Traceability could help uncover the origin and trafficking routes of this ammunition and then disrupt these routes. In criminal investigations, the origin of the ammunition can often provide crucial clues for solving a case. Clear marking and traceability allow governments, for example, to better control who buys, sells, or exports ammunition, thereby ensuring that it does not fall into the wrong hands.

[0005] Various methods of marking ammunition during its manufacture are known in the prior art, such as chemical or biological marking, marking with agents like gadolinium, marking by mechanical imprinting, marking with lasers or other focused thermal energy, and / or electrotechnical marking, e.g., using RFID tags. However, these methods of marking ammunition are sometimes very complex and only feasible with considerable effort and expense. Furthermore, depending on the nature of the marking, in some cases, it can lead to a loss of the weapon's effectiveness, for example, its accuracy. Electrotechnical solutions, in particular, have reliability issues, especially due to the destruction or damage of the marking during firing. Other markings can also be destroyed or damaged by firing.Other problems that have prevented any of the aforementioned solutions from becoming established include, for example, their lack of general acceptance, their lack of interoperability, limited reach of the technologies, lack of connections via appropriate databases, data protection or other regulations, the low added value in operational application, and a lack of doctrinal foundations.

[0006] The marking of ammunition / cartridges during their manufacture does not allow for the attribution of at least some parts of the ammunition / cartridges to the firearm from which they were fired. This information is particularly important in criminal investigations and forensic studies, especially since firearms are often registered and their owners are therefore known. Even after firing, identical but marked cartridges fired from identical firearms with identical chambers exhibit similar differences, which are difficult to detect at all, except for the marking. The invention therefore aims to provide a method for analyzing a cartridge case fired from a chamber, a firearm chamber, and a firearm with such a chamber.to design and / or further develop the technology in such a way that the problems of the prior art are avoided, or at least reduced. In particular, it should be possible, preferably in a simple manner, to unambiguously assign a cartridge chamber or an associated firearm to at least parts of a cartridge fired from this cartridge chamber, especially by means of this firearm.

[0007] This problem underlying the invention is now first solved by a method for analyzing a sleeve with the features of claim 1.

[0008] One aspect of the invention essentially lies in the fact that the cartridge chamber is designed to influence the flow behavior of the cartridge case during firing in such a way that a frequency spectrum, in particular a natural frequency spectrum, of the cartridge case is formed after firing according to an identification code, wherein the cartridge case is excited to vibrate, wherein the vibrations of the cartridge case are detected, wherein the frequency spectrum of the cartridge case is determined from the detected vibrations, and wherein the identification code is determined from the frequency spectrum.

[0009] The frequency spectrum can be determined by exciting the sleeve to vibrate with one or more specific frequencies or an excitation spectrum of excitation frequencies, and recording the frequency spectrum emitted by the vibrating sleeve. Preferably, the natural frequency spectrum is determined. However, it is also conceivable that the natural frequencies are not determined, but rather that only the frequency spectrum recorded according to a defined test protocol is used to determine the identification code.

[0010] This allows for a simple and unambiguous assignment of the cartridge chamber to a cartridge case fired from that chamber. The identification code marks the case in relation to the individual cartridge chamber. Due to the high pressure in the chamber during firing, the case deforms, expanding primarily radially, but also axially, elastically and plastically. The term "flow behavior" refers to plastic expansion. Through plastic expansion, the shape of the case, particularly its outer contour, adapts to the shape of the inner circumference of the cartridge chamber. No modification of the ammunition is necessary; that is, commercially available cartridges can be used.This type of cartridge case marking prevents any loss of performance in the firearm's chamber, ensuring that the firearm's accuracy is not reduced by the marking process. The alteration of the chamber's shape does not significantly affect the weapon's function or ballistics. Despite this, the marking is reliably generated with every shot. This provides a solid foundation for the widespread acceptance of this technology. Furthermore, marking the cartridge case during firing allows for the identification of the cartridge case and the specific firearm from which it was fired, which is crucial for solving crimes. The identification code is generated by the natural frequency spectrum, which exhibits predetermined amplitudes at specific frequencies.The identification code can be converted into a string of characters, e.g., a numerical code. Such a string is particularly easy to process digitally and can be compared with previously known information.

[0011] The vibrations that occur during firing can be simulated. Using computer software, for example for finite element analysis (FEA), complex structures of the deformed cartridge case can be modeled and their natural frequencies calculated numerically. This makes it possible to design the chamber so that the fired cartridge cases exhibit a specific natural frequency spectrum. This method allows for the creation of realistic models of the fired cartridge case and the design of its natural frequency spectrum.

[0012] The natural frequency spectrum of a sleeve describes the specific frequencies at which the sleeve can naturally vibrate or oscillate. Every sleeve has a unique set of natural frequencies, which depend on its physical properties such as material, shape, size, and structure. When a sleeve is mechanically excited, for example, by an external force or a shock wave, it oscillates at a frequency that corresponds to or is close to one of its natural frequencies. Natural modes are the characteristic vibration patterns of a physical system such as a sleeve or mechanical component. These vibration patterns correspond to the system's natural frequencies. Each natural mode has a specific frequency and a specific spatial distribution of vibration or deformation within the system. Natural modes can exhibit complex waveforms. Natural modes determine how a system responds to external excitations.When the system resonates with an external excitation, the vibration is amplified. Advantageously, the sleeve is continuously excited to vibrate, particularly at different frequencies, over a measurement period. One method for exciting a test specimen such as the sleeve is described in DE 4 330 752 A1, where an acoustic quality test of the specimen is performed. During the excitation of the sleeve, its natural frequency spectrum is superimposed on the vibration excitation, and this superposition allows the determination of the natural frequency spectrum. Continuous excitation of the sleeve also allows the natural frequency spectrum of sleeves with a low tendency to vibrate to be determined with sufficient precision.

[0013] According to an alternative embodiment of the method, the sleeve is excited to vibrate only once. This can be achieved by an impulse such as a blow. After this excitation, the sleeve then vibrates at its natural frequencies, generating its natural frequency spectrum, until the vibrational energy is dissipated by the damping of the sleeve. Thus, the natural frequency spectrum can be directly determined or measured due to the single excitation. The measurement period then lies between the single excitation and the point at which the vibrational energy is dissipated.

[0014] Preferably, the vibrations of the sleeve are detected using at least one microphone, in particular an airborne microphone and / or a contact microphone. This allows for precise determination of the frequency spectrum. The recorded vibrations are preferably converted into an electrical signal by the microphone, which is then particularly easy to analyze. More preferably, the analog electrical signal is converted into a digital signal by appropriate sampling, enabling further evaluation at the digital level using commercially available computers.

[0015] Preferably, the frequency spectrum of the sleeve is determined from the detected vibrations using Fourier analysis, in particular a discrete Fourier transform and / or a fast Fourier transform. Fourier analysis allows for the quick and easy determination of the frequency spectrum of the detected vibrations. A discrete Fourier transform is performed digitally. A fast Fourier transform is a special algorithm for the efficient and therefore rapid calculation of the discrete Fourier transform.

[0016] The problem underlying the invention is also solved by a cartridge chamber of a firearm with the features of claim 6. One aspect of the invention is essentially that the cartridge chamber is designed to influence the flow behavior of a cartridge case during firing in such a way that a frequency spectrum, in particular a natural frequency spectrum, of the case is formed after firing according to an identification code.

[0017] This allows for a simple and unambiguous assignment of the cartridge chamber to a cartridge case fired from that chamber. The identification code then marks the case in relation to the individual cartridge chamber. Due to the high pressure in the cartridge chamber during firing, the case deforms, expanding primarily radially, but also axially, elastically and plastically. The term "flow behavior" refers to plastic expansion. Through plastic expansion, the shape of the case, particularly its outer contour, adapts to the shape of the inner circumference of the cartridge chamber.

[0018] Preferably, the cartridge chamber has at least one bulge and / or constriction in the axial direction. Due to plastic expansion, the cartridge case then conforms to the contour of the bulge and / or constriction upon firing. After firing, the cartridge case exhibits a bell shape, particularly according to the bulge and / or constriction. The cartridge case also possesses a specific natural frequency spectrum after firing. Different bulges and / or constrictions are incorporated into different cartridge chambers, so that cartridge cases fired from different chambers have different, individual identification codes.

[0019] According to a further advantageous embodiment of the cartridge chamber, the cartridge chamber has at least one bulge and / or constriction in the circumferential direction. This provides additional parameters for influencing the frequency spectrum, thus increasing the information content of the identification code.

[0020] To create the bulges and / or constrictions, the chamber is preferably partially milled away. Specifically, the chamber is milled away in a hollow cylindrical area adjacent to which the cartridge case is positioned. This method makes it particularly easy to produce the bulges and / or constrictions. The hollow cylindrical area can initially be produced in the same way for all identical firearms. The bulges and / or constrictions are then individually created for each firearm. Preferably, the chamber is milled, ground, and / or polished. This further simplifies the creation of the bulges and / or constrictions.

[0021] Advantageously, the identification code includes a firearm registration code. This registration code is often already stored in databases in connection with the corresponding owner of the firearm. This information about the firearm's owner is particularly important in criminal investigations and can aid in clarifying the facts of a case. The owner of the firearm can also be identified by the marking on the cartridge case even if only the case, but not the firearm itself, is found at a crime scene.

[0022] The problem underlying the invention is also solved by a firearm with the features of claim 10. The advantages described above apply not only to a cartridge chamber, but also analogously to the firearm comprising the cartridge chamber.

[0023] Ideally, both the firearm and the ammunition should remain traceable from the factory.

[0024] There are now numerous possibilities for advantageously designing and further developing the inventive method for analyzing a cartridge case fired using a cartridge chamber, the inventive cartridge chamber of a firearm, and the inventive firearm with such a cartridge chamber. Reference may first be made to the claims subordinate to claims 1 and 6. In the following, a preferred embodiment of the inventive method for analyzing a cartridge case fired using a cartridge chamber, the inventive cartridge chamber of a firearm, and the inventive firearm with such a cartridge chamber will be explained and described in more detail with reference to the drawing and the accompanying description. The drawing shows:

[0025] Fig. 1a schematically represents a first embodiment of the cartridge chamber of a firearm with a cartridge arranged therein in a side view in section before firing the cartridge.

[0026] Fig. 1b shows a schematic representation of a frequency spectrum of a cartridge case before firing, Fig. 2a shows a schematic representation of the embodiment of the cartridge chamber from Fig. 1a with a cartridge case of a fired cartridge arranged therein in a side view in section,

[0027] Fig. 2b schematically shows a frequency spectrum of a cartridge case of a fired cartridge, and

[0028] Fig. 3 shows a schematic representation of a second embodiment of the cartridge chamber of a firearm in a sectional view perpendicular to the axial direction of the cartridge chamber.

[0029] The method for analyzing a cartridge case 1 of a cartridge 3 fired using a cartridge chamber 2 is made possible in particular by the cartridge chamber 2 shown in Fig. 1a, Fig. 2a and Fig. 3. This cartridge chamber 2 is designed to influence the flow behavior of the cartridge case 1 during firing such that a frequency spectrum 4, in particular a natural frequency spectrum, of the cartridge case 1 is formed after firing according to an identification code 5. Fig. 1b shows the frequency spectrum 4 before firing, and Fig. 2b shows the frequency spectrum 4 after firing.

[0030] During firing, a projectile 9 of cartridge 3, which is connected to the cartridge case 1 before firing, is accelerated in the axial direction S by the ignition of a propellant charge 10 of cartridge 3 located in the cartridge case 1, thereby detaching it from the cartridge case 1. The projectile 9 then travels through the barrel of a firearm 6, which has a chamber 2, and exits through the muzzle of the barrel. The ignition of the propellant charge 10 creates a high internal pressure of up to approximately 4200 bar within the cartridge case 1. This high internal pressure causes the cartridge case 1 to deform and conform to the chamber 2. This process is called compression. The deformation of the cartridge case 1 consists of an elastic and a plastic component. The plastic component causes the outer circumference of the cartridge case 1 to expand slightly during firing. In addition to this expansion, the cartridge case 1 also stretches in the axial direction S during firing, thus increasing its length.The high internal pressure results in a reduction of the case wall thickness. The material of the case 1 is sufficiently ductile to allow the described plastic deformation, namely the corresponding flow behavior, to occur. This flow allows the case 1 to conform to the contour of the cartridge chamber 2, as can be seen particularly clearly by comparing Fig. 1a and Fig. 2a. In the method for analyzing the case 1 of the fired cartridge 3, the case 1 is set into vibration. The vibrations of the case 1 are detected, and from these vibrations, the frequency spectrum 4, in particular the natural frequency spectrum, of the case 1 is determined. The identification code 5 is then derived from the frequency spectrum 4.

[0031] The identification code 5 can be read in this way, for example, after the cartridge case 4 has been found at a crime scene. The identification code 5 is then used to transform the cartridge chamber 1 into the shape of the cartridge chamber 2. The shape of the cartridge chamber 1 is designed such that the frequency spectrum 4 is formed according to this identification code 5. Before firing, the vibrations of the cartridge case 1, as shown in Fig. 1b, exhibit only slight changes in their amplitude A over a wide range of frequencies f. This is also referred to as a noisy sound. After firing, the vibrations of the cartridge case 1, as shown in Fig. 2b, exhibit pronounced signal peaks in amplitude A at certain frequencies f. This is also referred to as a sound with strong acoustic properties.

[0032] The sleeve 1 is continuously excited to vibrate and / or at a constant frequency f during a measurement period. The sleeve 1 can also be excited at different frequencies f during a measurement period, which then has corresponding effects on the frequency spectrum 4. During continuous vibration excitation, the sleeve 1 is preferably clamped in the region of a sleeve base 11.

[0033] It is also conceivable that the sleeve 1 is excited to vibrate only once. Subsequently, the sleeve 1 oscillates freely until the vibrational energy is dissipated. During this free oscillation, the natural frequency spectrum of the sleeve 1 is formed.

[0034] I is also preferably located in the area of ​​the sleeve base during a single vibration excitation.

[0035] II is clamped in place and struck with a mallet.

[0036] The vibrations of sleeve 1 are detected by means of at least one microphone (not shown here), in particular an airborne microphone and / or a contact microphone. An airborne microphone is positioned at a specific, short distance from sleeve 1. A contact microphone, e.g., with a piezo pickup, is mounted in contact with sleeve 1. Several microphones can also be used to detect the vibrations of sleeve 1.

[0037] The frequency spectrum 4 of sleeve 1 is determined from the detected vibrations using Fourier analysis, in particular a discrete Fourier transform and / or a fast Fourier transform. The Fourier analysis, in particular the discrete Fourier transform and / or the fast Fourier transform, is performed using a computer. For this purpose, the vibrations of sleeve 1 are converted into an analog electrical signal using the microphone, and this analog electrical signal is then converted into a digital signal that can be processed by the computer. The determined frequency spectrum 4 and / or the determined identification code 5 can then be displayed, for example, by a forensic scientist using a display device connected to the computer.

[0038] The cartridge chamber 2 is part of a firearm 6, with Fig. 1a, Fig. 2a and Fig. 3 also partially showing this firearm 6 with the cartridge chamber 2. A barrel of the firearm 6 is connected to the cartridge chamber 2.

[0039] The cartridge chamber 2 has at least one bulge 7 and / or constriction in the axial direction S. According to its first embodiment shown in Figs. 1a and 2a, the cartridge chamber 2 has a bulge 7 in the axial direction S that widens towards the breech face in this axial direction S with respect to the cartridge case 2 arranged in the cartridge chamber 2. The cartridge chamber 2, including the bulge 7, is preferably rotationally symmetrical. However, it would also be conceivable to provide bulges extending over limited angular ranges in the axial direction S.

[0040] According to its second embodiment shown in Fig. 3, the cartridge chamber 2 has at least one bulge and / or constriction 8 in the circumferential direction U. Fig. 3 shows three constrictions 8 evenly distributed around the circumference. However, there could also be only one, two, or more than three constrictions 8.

[0041] It is also conceivable that the bulges and / or constrictions form both in the axial direction S and in the circumferential direction U.

[0042] The cartridge chamber 2 is removed, in particular by a milling process, a grinding process, and / or a polishing process, to create the bulges 7 and / or constrictions 8. Other removal methods are conceivable. Alternatively, the bulges 7 and / or constrictions 8 could also be created by other (primary forming) processes without removal.

[0043] Identification code 5 contains a registration code for firearm 6. Other information may also be stored in identification code 5. Reference list.

[0044] 1 sleeve

[0045] 2 cartridge chambers

[0046] 3 cartridges

[0047] 4 Frequency spectrum

[0048] 5 Identification code

[0049] 6 Firearm

[0050] 7 bulge

[0051] 8 Narrowing

[0052] 9 projectile

[0053] 10 propellant charge

[0054] 11 Sleeve base f frequency

[0055] A Amplitude

[0056] S Axial direction

[0057] U circumferential direction

Claims

Patent claims 1. Method for analyzing a cartridge case (1) of a cartridge (3) fired with the aid of a cartridge chamber (2), characterized in that the cartridge chamber (2) is designed to influence the flow behavior of the cartridge case (1) during firing such that a frequency spectrum (4), in particular a natural frequency spectrum, of the cartridge case (1) is formed after firing according to an identification code (5), wherein the cartridge case (1) is excited to vibrate, wherein the vibrations of the cartridge case (1) are detected, wherein the frequency spectrum (4), in particular the natural frequency spectrum, of the cartridge case (1) is determined from the detected vibrations, wherein the identification code (5) is determined from the frequency spectrum (4).

2. Method according to claim 1, characterized in that the sleeve (1) is continuously excited to vibrate and / or at a frequency (f) during a measurement period.

3. Method according to claim 1, characterized in that the sleeve (1) is excited to vibrate once.

4. Method according to one of the preceding claims, characterized in that the vibrations of the sleeve (1) are detected by means of at least one microphone, in particular an airborne sound microphone and / or a structure-borne sound microphone.

5. Method according to one of the preceding claims, characterized in that the frequency spectrum (4) of the sleeve (1) is determined from the detected vibrations by means of a Fourier analysis, in particular a discrete Fourier transform and / or fast Fourier transform.

6. Cartridge chamber (2) of a firearm (6), characterized in that the cartridge chamber (2) is designed to influence the flow behavior of a cartridge case (1) of a cartridge (3) during firing such that a frequency spectrum (4), in particular a natural frequency spectrum, of the cartridge case (1) is formed after firing according to an identification code (5).

7. Cartridge chamber (2) according to claim 6, characterized in that the cartridge chamber (2) has at least one bulge (7) and / or constriction in the axial direction (S).

8. Cartridge chamber (2) according to claim 6 or 7, characterized in that the cartridge chamber (2) has at least one bulge and / or constriction (8) in the circumferential direction (U).

9. Cartridge chamber (2) according to one of claims 6 to 8, characterized in that the identification code (5) has a registration code of the firearm (6).

10. Firearm (6) with a cartridge chamber (2) according to one of claims 6 to 9.

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