Casting of shell casings with controlled fragmentation geometry

Abstract

A method for casting shell cases for technical purposes with a predicted nature of destruction has been substantiated and developed. The relevance of the research is driven by the need to create lightweight metal structures capable of controlled fragmentation into elements of a given mass under intensive high-energy impact, which is critical for single-use systems. Since traditional mechanical execution of grooves on the internal cavities of thin-walled bodies is economically inefficient and technologically complex, it is practically not used in mass production. The scientific novelty of the study lies in the mathematical substantiation of a geometric fragmentation criterion, which establishes an analytical relationship between the metal density, wall thickness, and the area of the section bounded by distribution grooves. The proposed criterion allows, at the design stage of the pattern tooling, to ensure the formation of fragments in the optimal mass range of 2 to 5 grams. This meets the requirements of functional efficiency through the implementation of the "gas wedge" physical effect. The paper describes the technological process of implementing the method using Lost Foam Casting (LFC). It is proved that the use of polymer patterns allows for the precise transfer of the complex geometry of stress concentrators from the mold directly into the casting, ensuring high surface quality and dimensional accuracy. Practical approbation of the method using the example of manufacturing cylindrical shell bodies from gray cast iron confirmed the possibility of producing a ribbed internal surface of the casting. The possibility of integrating such products with modern autonomous transport systems is considered, and a method for automatic unloading based on polymer fasteners that are thermally destroyed by an electrical signal is developed. The integrated approach, combining precision casting of bodies and innovative delivery methods, allows for reducing the metal consumption of production and increasing the efficiency of autonomous transport systems.