Pneumo-thermal molding of sandwich wedge-like panels from titanium alloy VT20

Аuthors

Kolesnikov A. V.^*, Kolesnik A. V.^**, Zabolotskii A. P.^***

Irkutsk National Research Technical University, 83, Lermontov str., Irkutsk, 664074, Russia

*e-mail: Avk@istu.edu
**e-mail: kemazik@mail.ru
***e-mail: donzab@ya.ru

Abstract

The presented work deals with considering pneumo-thermal molding and diffusion welding (PTM/DW) technology for multilayer structures manufacturing from titanium alloys, including the ones of variable height. The paper represents the presentation of general theory of the above said technology, and analysis of the problems emerging while its realization.

The author separated out the stages of PTM/DW technology of multilayer titanium panels.

The main problem considered in the paper consists in the problem of non-removable defects formation, accompanying manufacturing of multilayer wedge-like panels. These defects are imaged on the appended plots and figures.

The reason of these defects occurrence while multilayer panels molding lies in the different displacement of the lower shell in various areas of the pack of sheets. In the area of diffusion welding this displacement is constrained by ribs of the filler, while in the zones which are not welded with the filler, the upper shell is forming freely under gas pressure. Its deflections are forming herewith between the areas of welding with the filler.

Solution of this problem consists in defining the managing program, necessary to form the ribs of the filler and the shell, whereby the shell deviation in the areas unreinforced by the ribs would not reach critical value.

The recommended range of the shell and filler thicknesses ratio in dependence on the shell deflection in the areas unreinforced by the ribs, as well as equations for determining critical deflection factor and molding pressure were obtained by mathematical modeling.

Application of the above said equations for the filler and shell thicknesses of multilayer wedge-like panels will allow avoiding defects occurrence, which was confirmed in practice. All fabricated panels comply with the calculated parameters. No defects were detected over the profile section dimensions.

In view of the foregoing, one may state that the problem consisting in determining the regularities for selection of design and geometry parameters of multilayer structures, allowing ensure qualitative molding process without defects formation was solved successfully, and the solution has practical applicability.

Keywords:

pneumo-thermal molding, superplasticity, wedge-like sandwich panels, titanium alloy VT20

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