Combined drawing with heating of the stress relaxing material

The relations for calculating the modes of technology for the subsequent operation of combined drawing with heating of blanks made of highstrength aluminum and titanium alloys are proposed. During the deformation process, both the hardening of the material and its softening occur, which is associated with the exhibition of viscous properties (creep). Under conditions of isothermal deformation, the blank material is assumed to be viscoplastic, the deformation state is accompanied by stress relaxation. The lower the operation speed, the greater the relaxation is. It is assumed that the design drawing scheme consists of a bending area of the blank wall at the entrance to the die, a conical area and a thinning area of the wall in the drawing gap of the die. Deformation also occurs on the surface of the velocity discontinuity during the transition of the blank from the die cone to the drawing ring. The friction on the contact surfaces of the tool and the blank is taken into account. Analytical relations have been obtained for estimating the power of plastic deformation, strength, and damage of the blank material during isothermal combined drawing on a conical die. The specific force of the operation is determined using the basic energy equation, which establishes the balance of the capacities of external and internal forces. The damage capacity of the blank material is estimated in accordance with the energy criterion of fracture mechanics. Based on the obtained relations, calculations of the specific strength and damage of the material during the subsequent operation of isothermal combined drawing of cylindrical products made of aluminum and titanium alloys at processing temperatures of 450 and 850 оC, respectively, depending on the tool speed, have been performed. It has been found that in the speed range from 5 to 100 mm/min, the materials under study exhibit viscous properties, and reducing the drawing speed helps to reduce the technological force and damage of the blank material.