Mathematical model development for superplastic forming of sheet shells by subliming agent gas pressure

Oleksandr Anishchenko,Alla Vorobeva,Volodymyr Kukhar,Viktor Agarkov,D Rudoy,V Murgul

doi:10.1051/e3sconf/201913501002

Abstract

The authors presented in the article an analytical model of superplastic forming of spherical shells by pressure of the gas (gaseous phase) created upon sublimation of sublimate agent. Sublimate was placed in a hermetic cavity between the workpiece and the presser cover and heated to the temperature of its sublimation. The model uses the Berthelot equation for the state of real gases, the Bernoulli relation, and the F. Jovane equations for adjusting the shell forming pressure as a function of its relative height, the heat balance equation for the sublimation process, and the Clausius-Clapeyron relation for sublimation of substances. The authors showed that the superplastic forming pressure control can be effectively applied by the way of change in the forming temperature relative to temperature of sublimate agent sublimation. The experimental results of forming of shells from aluminum alloys AlMg3Mn, AlMg5Mn and AlMg6Mn, confirming theoretical calculations of the velocity and temperature conditions of superplastic forming by the sublimating agent pressure.

Highlights

Superplastic forming of spherical shells from sheets is performed by a gas medium, and aluminum and titanium based alloys are preferably formed [1,2,3,4,5]
Replacement of the external gaseous medium to the internal gas medium will significantly facilitate the technological realization of the gas superplastic forming (Fig. 1), while it is obvious that the methods for taking into account the material plastic properties and the designing of the passes will remain the same [5, 6, 8, 15, 21,22,23]
1.An analytical model of superplastic forming of spherical shells by the pressure of a gas medium created during the sublimation of sublimate agent in the die cavity is developed

Summary

Introduction

Superplastic forming of spherical shells from sheets is performed by a gas medium, and aluminum and titanium based alloys are preferably formed [1,2,3,4,5]. One of the modern and progressive variants of superplastic forming is the molding of shells by the pressure of a gaseous medium formed as a result of a change in the aggregate state of thermo-metastable substance (sublimate or destruct agent) in the hermetic die cavity [8, 9]. Based on this kind of gas forming, in this work an attempt is made to determine the optimal power regime in relation to free forming of dome-shaped shells due to the controlled sublimation in the die cavity.

Methodology

Conclusions