METHOD OF STRETCHING OF COMPLEX LARGE PARTS (VARIANTS) Russian patent published in 2012 - IPC B21D22/22 

FIELD: sheet-metal stamping.

SUBSTANCE: invention relates to sheet-metal stamping; the method includes laying of the work-piece, clamping of the flange of the work-piece, retracting of the central part of the work-piece by the centre punch into the matrix working space along its outline with the simultaneous restraining of the work-piece flange by means of the over-winding cusps; the matrix outline adds to the plan of rectilineal or curvilineal crowned pieces with rounded corner pieces; according to the first variant the over-winding cusps are placed on the flat clamping surface of the matrix and restraining of the flange is executed by the sliding member of the press or automatic machine; according to the second variant the over-winding cusps are positioned on the spatial unfolding clamping surface of the matrix and restraining of the flange is executed by the sliding member of the pressing unit or the automatic machine; according to the third variant the over-winding cusps are placed on the matrix and restraining of the flange is performed by the sliding member of the pressing unit or automatic machine; according to the forth variant the over-winding cusps are placed on the matrix and restraining of the flange is performed by the pressing buck; according to the fifth variant the over-winding cusps are placed on the clamping plate and restraining of the flange is performed by the pressing buck.

EFFECT: invention allows to avoid crustal folding of the work-piece.

5 cl, 9 dwg