Form-fit joining behaviour between an aluminium tube and sheet using electromagnetic forming

The electromagnetic forming (EMF) process is a typical high speed forming technique using Lorentz forces generated by interaction between the magnetic field and induced electric current. Recently, researchers have discussed form-fit joining using tube compression by EMF without additional connection elements for application in the industry. This paper provides analysis into the form-fit joining behaviour achieved by tube expansion using EMF. The aluminum 6063 tube was inserted into an aluminum 7075 sheet with hole of the same size as the diameter of the tube, and they were fixed on the coil. The flanging and bulging of the tube were simultaneously conducted by the magnetic force with given charging voltage, and then the form-fit joining was achieved between the tube and sheet. To investigate the effect of the input voltages, the experiments were performed with various charging voltages from 5.7 kV up to 11.1 kV. In addition, the connection strength of the joined specimen was measured by the pull-out test between the tube and sheet. As a result, the connection strength was stronger than the yield strength and lower than the tensile strength of the aluminum 6063 tube.