FRICTION-FREE STUDY OF THE EXTRUSION PROCESS OF A SINTERED THIN-WALLED PIPE LOADED BY INTERNAL HIGH PRESSURE WITH A BOUNDARY CONDITION AT THE ENTRY INTO A DIE

Abstract

The problem of pipe extrusion in the absence of friction applying meridional pressure to the cross section at the entrance into the matrix has been solved by two methods. In the first case, the method of obtaining an exponential function with a natural base is used by transforming the corresponding formula obtained by solving this problem with the friction factor by expanding this function into a series, and in the second case, the basic equation of equilibrium is simplified by substituting zero instead of the coefficient that takes into account friction (k=0).

Dimensionless values of meridional, circumferential and average stresses are determined depending on the degree of deformation of the pipe, which allows to study the process of compaction of the pipe at different initial values of porosity of the material using the formulas of the deformation theory of plasticity of porous materials. Computer modeling of the process was performed in the MS EXEL software environment at different values of the initial meridional dimensionless compression stresses. The process of extrusion of the pipe will correspond to such an initial value of voltage, at which the meridional voltage of the pipe at the exit from the matrix will be equal to zero.

Changes in the material curves of pipes with initial porosity of 10, 20, and 30% indicate that in the absence of contact friction, the porosity becomes zero, at values of the intensity of deformation s_i – 0.142, 0.137, and 0.132, respectively. The results were compared with the data obtained for the case with taking into account friction.