金属板料在压弯过程中,中心层上部的金属随着几何空间的增大,在径向拉应力的作用下,向弯曲方向的两端流动,表层的金属纤维向中心层贴近,板料厚度变薄,从而保持其体积相等。中心层下部的金属随着几何空间的缩小,在径向压应力的作用下,不得不向弯曲方向的两端搓动,部分金属流 Metal sheet material in the bending process, the upper center of the metal layer with the geometric space increases, under the action of radial tensile stress to the bending direction of the two ends of the surface layer of metal fibers to the center layer close to the sheet metal The thickness is thinner, keeping its volume equal. The lower part of the center layer of the metal with the reduction of geometric space, under the effect of radial compressive stress, have to twist the ends of the bending direction, part of the metal flow