Research on controllability of final macroscopic specimen shape in electromagnetic superposed forming

Abstract

Electromagnetic superposed forming (EMSF) is a newly proposed method for forming large-scale aluminum alloy sheets with small curvature. The forming principle is based on superposition of local shallow deformations generated by the coaction of a flat spiral coil and a punch matrix. This paper emphasizes the deformation controllability, which is a basic research for developing the EMSF into a mature process of forming aircraft skins. The study is conducted via forming experiments in which the sheet blanks with different length-width ratio are entirely or partially subjected to the pulsed electromagnetic force. Finally, two pieces of S-shaped specimens are trail-produced. Waviness and surface finish of the specimens are analyzed. The results show that obtaining spherical specimen by EMSF is feasible. When a square blank is uniformly loaded, the specimen shape is approximately spherical. It is also feasible to obtain the major deformation perpendicular to loading paths in EMSF. The controllability of deformation during the EMSF process can be ensured. The S-shaped specimens show potential application of the EMSF in forming parts with complex shape. Besides, the specimen waviness is suitable for aircraft skins.