Tula State University, Tula, Russia:

S. N. Larin, Doctor of Technical Sciences, Professor at the Department of Plastic Forming Mechanics, e-mail: mpf-tula@rambler.ru

A. A. Pasynkov, Сandidate of Technical Sciences, Associate Professor at the Department of Plastic Forming Mechanics, e-mail: mpf-tula@rambler.ru

Russian University of Transport, Moscow, Russia:

V. N. Chudin, Doctor of Technical Sciences, Professor at the Department of Strength of Materials and Construction Mechanics

Hollow cylindrical and tapered parts with internal upset ends often serve as bodies in equipment designed for different applications. Such specialized equipment is designed on the basis of specific requirements regarding the weight and strength of such parts, and such requirements can be satisfied when using high-strength non-ferrous alloys. Use of pressure forming for such parts can often be labour intensive. The benefit of using isothermal deformation in this case includes higher deformation ratios and lower specific pressures. With the help of energy method, this research study looks at internal upsetting of a tapered body in viscoplasticity mode. The conclusion drawn is that the process is not stationary. The state of viscoplasticity was combined with an axisymmetric deformation pattern. The paper describes a process flow chart and ratios to calculate the kinematics, pressure and damageability of the workpiece material when heat is applied during upsetting. The design was performed for a tapered body made of the high-strength aluminium alloy AMg6 and chromium-nickel alloy VNS25 that is subjected to upsetting at the temperatures and rates ensuring viscoelastic flow. Design data were obtained. A relationship was established between creep and work hardening and softening of the workpiece material. Thus, relaxation intensifies as the upsetting process slows down or extends in time. The authors established how the upsetting pressure and the damageability of the material change in the course of upsetting; the effect of creep on the upsetting pressure and the degrees of forming as the thickness of the part grows. The paper describes sample parts and includes drawings of pipe upsetting dies.
This research study was carried out as part of the governmental grant NSh-2601.2020.8 aimed to support leading scientific schools of the Russian Federation.

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