The Influence of Pre-forming on Hydroforming of Extruded Aluminum Tubes
The conventional tube hydroforming process involves the use of internal pressure and axial feed applied to a tubular section which expands to fill an external die. However, axial feed is not possible for many industrial applications where complex geometrical features hinder lateral material flow. In such cases, the achievable circumferential strains for the required shape changes must be minimized to avoid premature failure. Pre-forming by die closure (i.e., crush forming) is often used to acquire desired cross-sectional shapes. This paper discusses the effects of this type of pre-forming operation on the formability of an AA6063-T4 alloy during hydroforming. A cylindrical tube was first crushed with flat punches and then hydroformed. This two-step forming process was investigated using a wellcoordinated experimental and numerical study. The simulations are extended to investigate an intermediate heat-treatment step between the pre-forming and hydroforming operations and the results are discussed.
A.R. LOUKUS, G. SUBHASH, Henry VALBERG
Aluminum Extrusions, Hydroforming, Pre-Forming, Formability, FE Simulation.