METHOD FOR MANUFACTURING HOLLOW PARTS Russian patent published in 1994 - IPC

FIELD: plastic metal working. SUBSTANCE: initially the blank material is tested to stretching to define the mean statistic elongation. The deformation localization coefficient through the material thickness K_δ is measured electrically. The semifinished product is preliminary stretched to dimensions in plane and through the height smaller than the corresponding dimensions of the finished article. Then the final stretching to required dimensions is performed. The pressing force during preliminary and final stretching is constant. The article dimensions are determined considering K_δ according to design relations. EFFECT: improved quality. 3 cl, 2 dwg