Simulation of Ironing Process for Bullet Case to Get Minimum Forming Force with Variation of Die Angle and Reduction Wall Thickness

Abstract

This study described how the ironing process to manufacture 20 mm caliber bullet case. For this purpose, the first step is analyzing the process parameters, and then calculates the forces needed to make the formation of bullet case. Through the analysis of the process it is known, that the ironing process parameters most influential to the magnitude of forming force are the die angle α and the reduction of the wall thickness. In this study a simulation is conducted to determine a minimum required of forming force until the process successful. That means the required bullet case accordance with the determined specifications and geometry. The material used for bullet case caliber 20 mm is brass Cu30% Zn 70% early-shaped cup with 33.5 mm outer diameter, 3 mm thick and 37 mm high. Based on material strength calculation, the ironing force is determined with value of 50.01 kN. By using this value the maximum allowable wall reduction thickness in the ironing process is 26.7%. The simulation is carried out using finite element method on a variety of die angle such as α = 5°, 10°, 15°, 20° and 25° respectively. The simulation results show that the shell cannot through the die on each angle die. Similarly, in variation of reduction by 5%, 10%, 15%, 20% and 25%, the ironing process is also unsuccessful. However, by load of 138 kN, in the 26.7% reduction and at die angle α=5°, the ironing process to produce cylinder is successfully. Similarly by the same of wall thickness reduction, with force of 148 kN and the die angle of 10°, the ironing process is also successfully to fulfill the bullet case with a specified geometry.

Design of a Combined Redrawing-Ironing Process to Manufacture a CNG Pressure Vessel Liner

“…Based on this stress, the most optimal condition was selected [12]. Mukhtar et al conducted a simulation of an ironing process for a caliber bullet case to determine the minimum forming force on a variety of die angle and thickness reduction rates [13]. Khodsetan et al proposed a new ironing method called constrained ironing for producing thin-walled cans and components with uniform thickness [14].…”

Untitled

“…Pada penelitian tersebut menunjukkan bahwa tegangan yang terjadi pada dinding cup sangat bervariatif, namun yang paling tinggi adalah pada bagian paling bawah cup mendekati dasar dengan nilai tegangan sebesar 348 MPa dengan sudut dies Ironing 25⁰. Selain itu pada penelitian [9] yang melakukan penelitian serupa, menunjukkan bahwa dari analisis FEA yang telah dilakukan dapat menginterpretasikan perkiraan hasil yang kemungkian akan terjadi jika tegangan yang diterima sama dengan saat part tersebut dibuat dalam bentuk/dimensi sebenarnya.…”