PROCEDURE FOR DRAWING COMPLEX LARGE-SIZE ITEMS IN PUNCH AT DOUBLE ACTION PRESS (VERSIONS) Russian patent published in 2011 - IPC B21D22/26 B21D37/00 

FIELD: metallurgy.

SUBSTANCE: work piece cut of sheet material and preliminary bent is drawn in double action press in punch with travelling central part of matrix. During drawing the central part of matrix creates pressing force of the central part of a work piece with preliminary peripheral part of work piece pressing. According to the first version force of springs positioned under the central part of the matrix is set higher, than force of deformation of a part of the work piece located over this part of the matrix during whole process of work piece deformation. According to the second version force of springs positioned under the central part of the matrix is set lower, than force of deformation of the work piece part located under this part of the matrix during an initial stage of drawing and higher, than force of deformation of this work piece part during intermediate and final stage of drawing. According to the third version force of springs is set lower, than force of deformation of the work piece part positioned over the central part of the matrix during an initial and intermediate stages of drawing and higher, than force of deformation of this work piece part during a final stage of drawing.

EFFECT: reduced fatigue strength, corrosion resistance and accuracy of items, reduced waste of sheet material and labour input.

3 cl, 7 dwg