Investigation of boundary conditions on the contact surface when drawing on free floating-plug

The article presents results of a numerical study of the stress state in the drawing of tubes on free floating-plug. In particular, the condition of the balance position of free floating-plug in the deformation zone is analyzed. For this study, used a mathematical model that takes into account the real nature of the hardening of metal and the distinction in boundary conditions on the contact surface of the pipe with a die and a plug. An analysis of the results obtained showed that the range of boundary conditions on the contact surface can be significantly expanded in comparison with what is currently being accepted. The estimation of applicability in practice of the received information is given. For this purpose, the dependence of the change in friction coefficient on the drawing speed for various lubricants has been studied. The results confirmed the possibility of implementation the boundary conditions established at modeling. Recommendations are given on the use of the lubricants considered, depending on the speed drawing of pipe.