In the drawing die structure, the nitrogen spring was used as the drawing die ejecting components. The traditional rubber or metal spring pressure boundary components were replaced. The problems of crack and wrinkle in drawing forming were solved well. Because the nitrogen spring had stable constant and elastic properties, the pressure-pad-force was always maintained at a stable numerical range. So the material can be processed smoothly into the cavity. The magnetic yoke parts were not broken and the circumferential surface was smooth. The drawing performance of materials was greatly improved. So the low price hot rolling acid steel plates using this technology were used in the drawing. The production cost was greatly reduced.
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