1, the plane flange area is the main deformation area, which bears radial tensile stress and tangential compressive stress, tangential compression, radial elongation deformation and compressive stress in the thickness direction.
2. In the fillet part of the flange, the material deformation is complex, including radial tensile stress, tangential compressive stress and thickness compressive stress, and the deformation state of this area is also three-dimensional.
3. In the pipe wall part, the diameter will not change due to the flange during drawing, that is, the tangential strain is 0. If the gap is appropriate, the thickness direction is not stressed, resulting in radial tensile stress, and this area is deformed into a plane state.
4. At the bottom fillet, the material bears large radial tensile stress of the cylinder wall, pressure of the punch fillet and compressive stress in the thickness direction, and tangential tensile stress during bending.
5. At the bottom of the cylinder, at the beginning of stretching, the material is pulled into the concave die, which keeps the plane state and basically does not deform. However, due to the tensile stress of the bottom fillet, the material is subjected to biaxial tensile stress, and the thickness is slightly thin.