Methods of electromagnetic forming aluminum alloy wheel for automotive use

A method of manufacturing an aluminum alloy wheel for automotive use, comprising the steps of:

• disposing a columnar workpiece in a metal mold for electromagnetic forming, with the inner peripheral face of the metal mold serving as a forming face for the outer peripheral side of the columnar workpiece having a wall thickness uniform throughout a body thereof;
• disposing a coil for electromagnetic forming on the inner peripheral side of the columnar workpiece;
• throwing electric energy into the coil for electromagnetic forming of the columnar workpiece, thereby causing the columnar workpiece to undergo flaring to be pressed against the forming face of the metal mold for electromagnetic forming, and forming a wheel rim having a drop part small in outside diameter, and two side parts each larger in outside diameter than the drop part, so that a flaring ratio of each of the two side parts is greater than that for the drop part;
• forming a disc separately from the wheel rim;
• and
• joining the disc to the inner peripheral face of the drop part of the wheel rim.

A method of manufacturing an aluminum alloy wheel for automotive use, comprising the steps of:

• disposing a columnar workpiece in a metal mold for electromagnetic forming, with the inner peripheral face of the metal mold having a plurality of steps and serving as a forming face for the outer peripheral side of the columnar workpiece;
• disposing a coil for electromagnetic forming on the inner peripheral side of the columnar workpiece;
• causing the columnar workpiece to undergo flaring to be pressed against the forming face of the metal mold in a single forming step by throwing electric energy into the coil for electromagnetic forming of the columnar workpiece, thereby forming a wheel rim having a drop part small in outside diameter, and two stepped side parts each larger in outside diameter than the drop part, so that a flaring ratio of each of the two side parts is greater than that for the drop part;
• forming a disc separately from the wheel rim;
• and
• joining the disc to the inner peripheral face of the drop part of the wheel rim.

A method of manufacturing an aluminum alloy wheel for automotive use, comprising the steps of:

• disposing a columnar workpiece in a metal mold for electromagnetic forming, with the inner peripheral face of the metal mold having a plurality of steps and serving as a forming face for the outer peripheral side of a columnar workpiece;
• disposing a coil for electromagnetic forming on the inner peripheral side of the columnar workpiece;
• and
• causing the columnar workpiece to undergo flaring to be pressed against the forming face of the metal mold in a single forming step by throwing electric energy into the coil for electromagnetic forming, thereby forming a wheel rim having a drop part small in outside diameter, and two stepped side parts each larger in outside diameter than the drop part, so that a flaring ratio of each of the two side parts is greater than that for the drop part.