To provide a burring processing method which can form a magnesium alloy made plate of a low material elongation by preventing generation of a crack at a flange tip and a breakage at a root of the flange when burring forming is performed by a press processing.
A plate material 4 is heated to a temperature at which an elongation is increased instantly by temperature adjusting heaters 9 arranged in a stripper plate 2 and a die plate 3 so as to perform a forming with a burring punch 5 against a bottom hole 8 of the burring. Thereby, at a tip end 12 of a flange 11 and at a root 13, the burring processing can be performed in a way that a tensile strength is not exceeded in a circumference direction at the flange tip part and the tensile strength in a flange vertical direction is not exceeded; resulting in forming of the burring having no crack at the flange tip end and no breakage at the flange root.
TANSHIN MASAYA
TAKEGAWA ATSUO
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