STUDYING THE EXTRUSION PROCESS OF A SINTERED THIN-WALL PIPE LOADED WITH INTERNAL HIGH PRESSURE IN CASE OF A BOUNDARY CONDITION IN THE DIE INLET

Abstract

An analytical study of the process of sintered thin-wall pipe extrusion loaded with internal high pressure, on its cross section in the conical die inlet by compressing meridio¬n¬a¬l dimensionless stress has been carried out. It is assumed that the external die pressure p_v and the internal high pressure p_r acting on the pipe are equal. In this case, the circumferential stress is determined and a simplified plasticity condition is obtained. The dimensionless values of meridional, circumferential and average stresses depending on the degree of pipe deformation were determined, which made it possible to study the processes of their compaction using the DTPPM equations at different values of coefficients of friction and initial porosities of the pipe material. A computer simulation of the process was carried out in the MS EXEL software environment, presetting different initial values of the compressive meridional dimensionl¬e¬s¬s stress. The pipe extrusion process will correspond to such an initial value of this stress, when the meridional stress of the pipe in the outlet of the die is equal to zero. In this case, the value of strain intensities is ε_i=0.258. The graphs of changes in 10, 20 and 30% of the initial porosities of the material show that the porosity becomes zero in the interval of value of deformation intensities ε_i from 0.116 to 0.132, and also in the case of large values of porosities and contact friction, the compaction of the material occurs more intensively.