ВЛИЯНИЕ ПЕРЕМЕННЫХ СИЛ ТРЕНИЯ НА РАЗМЕРЫ ЗОН СКОЛЬЖЕНИЯ, ТОРМОЖЕНИЯ И ЗАСТОЯ ПРИ ОСАДКЕ ПОЛОСЫ

Abstract

The analyses of new solutions to determine the contact stress in zones with variable frictional forces for upsetting the rectangular strip were executed. It is shown that replacement of the Mises precise plasticity condition by an approximate condition in terms of primary stress changes the character of curves contact stresses in the slip and dead zones, and significantly influences on the dimensions of these zones. It was established that with the decrease of the friction force at the boundary of the dead zone its width increases. As a result of numerical analysis of the stress state at the dead zone dependence of its width from the value of contact shear stresses on the boundary of dead zone was proposed. Conditions of existence and sizes of the slip, retardation and dead zones on the contact surface of the deformation region were installed in dependence on friction coefficient and relative width of the strip. Considering distributions of the contact stresses, expressions to determine the efforts of the upsetting process were found. The results were compared with known experimental and theoretical data. The estimation of error calculation effort of upsetting was obtained by the engineering methods. © 2017, National University of Science and Technology MISIS. All rights reserved.