Cryogenic deep drawing of aluminum alloy AA6014 using macro-structured tools

Abstract

For functional lightweight construction, 6xxx aluminum alloys are essential materials for exterior components due to their low weight to stiffness ratio and acceptable formability. The formability of the 6xxx alloys is lower compared to other aluminum alloys but they are free of flow lines. MOUSAVI ET AL. [1] demonstrate an alternative method of improving the forming limit with a deep drawing process using macro-structured tools. Another approach increasing the formability of aluminum alloys is forming at cryogenic temperatures [2]. This paper presents an advancement of deep drawing on macro-structured tools at cryogenic temperatures. This assumes a lower heat flux due to the reduction of the contact area between the blank and deep drawing tools, enabling forming at cryogenic blank temperature. After characterization of the material, experimental investigations are carried out on a cup test geometry. In addition to the required punch force at different temperatures, this paper presents the influence of macro-structured tools at cryogenic temperatures on springback and hardness distribution. Finally, the extension of the process limits and options by cryogenic macro-structured deep drawing are discussed.

Influence of Macro-Structured Tools on the Formability of Aluminum Alloys in the Cryogenic Temperature Range

“…Subject of the study are numerical and experimental investigations regarding the formability of the aluminum alloy AA6014 in a deep drawing process with macro-structured tools at cryogenic blank temperatures. The object of this investigation is the increasing drawing ration of AA6014 and represents the continuation of the preliminary tests in [10]. It is assumed that the line contact between the macro-structured tools and the blank results in a reduction of the heat flux between tools and blank that enables deep drawing with improved material properties at cryogenic temperatures of the sheet metal.…”

“…This leads to the question, if the combination of approaches results in an increasing process window. In [10] it was already shown that deep drawing of aluminum sheets with a sheet temperature in the cryogenic range with macro-structured tools leads to a reduction of the required punch force and spring back.…”