Cold stamping of a cartridge case blank for 40x53 mm caliber grenade launcher ammunition

Problems. The choice of a rational method for stamping blanks with two hollows is usually carried out according to the permissible degree of deformation, the coefficient of material utilization, and the productivity of the process without taking into account the effect of the deformation pattern on the final mechanical properties of the stamped semi-finished product. Purpose of the study. Determination of a rational method for stamping a blank of a 40x53 mm grenade launcher cartridge case based on the results of computer modeling using the finite element method. Cartridge case material - AD35 aluminum alloy. The workpiece has two hollows with different diameters and depths. Implementation technique. By means of computer modeling using the finite element method, two options for stamping of a workpiece are researched - double-sided extrusion and sequential reverse extrusion with tilting of the workpiece. Research results. Based on the results of the research, the features of deformation according to the given schemes, as well as the energy-force parameters and parameters of the stress-strain state of the processes, are determined. It has been established that both methods make it possible to obtain blanks with specified geometric dimensions. At the same time, sequential back extrusion provides a more uniform and predictable deformation of the material along the cross-section of the workpiece, but loses in productivity to double-sided extrusion. Conclusions. The obtained research results can be used as criteria when choosing the optimal option for stamping of a workpiece with two hollows by cold extrusion.

Digital double of special purpose products

The article suggests the use of a promising technological process for manufacturing a cartridge case for sporting and hunting cartridges using the key operation of double-sided semi-hot extrusion with distribution. The advantages of the new technological process for the production of special-purpose products are justified. To test the cartridge case for the effectiveness of its operation when fired, the ANSYS finite element analysis software system developed a digital cartridge case double, which made it possible to demonstrate the impact of design changes, environmental conditions, and other factors on the product. The analysis of the digital double showed that the sleeve made using the semi-hot extrusion technology has sufficient strength.

THE PROBLEM OF SUBCLASS CHARACTERISTICS WHILE EXAMINATION OF REDESIGNED FLARE GUNS

In the process of cartridge case forensic identification common and separate (individual) characteristics are distinguished. Common characteristics are typical for a certain construction/model of firearms and are used for identifying the cartridge case group affiliation. Individual characteristics are random and are used for determining identity. Subclass characteristics appear at the stage of mechanical processing of the firearms’ parts. Therefore, the same marks can be observed on a few parts, which were consequently processed by the same tool. Lack of knowledge on the differences between individual and subclass characteristics may result in wrong conclusions as to identity. The article purpose is to acquaint ballistic forensic experts with the problem of subclass characteristics, mechanism of their occurrence and the ways for their determination. The mechanism of subclass characteristics occurrence and the characteristics on the basis of which we can determine that the examined characteristic is individual or subclass are discussed. The main examples of subclass characteristics, such as lands and grooves, arches, circles for which the width, depth and relative position of each element coincide, were given. The peculiarities of scene which allow to determine the individual characteristics among subclass characteristics are presented. Such features include the presence of irregularities along the lands and grooves, which make up the subclass feature, the cross section of the lands and grooves, etc. The possibility of identifying subclass characteristics is illustrated by the real case from forensic practice while redesigned flare gun examination. The article highlights the need regarding the ability to determine subclass characteristics and the influence of such characteristics on the possibility of drawing up a conclusion as to identity.