FRICTION EFFECT DURING HOT REVERSE EXTRUSION OF HOLLOW SEMI-FINISHED PRODUCTS FROM ROUND AND SQUARE BLANKS

Abstract

Mathematical models have been created by the finite element method using the DEFORM-3D program and a computational analysis of the processes of hot reverse extrusion of hollow semi-finished products made of low-carbon steel from cylindrical and square blanks has been carried out. The effect of friction coefficients of μ=0.15, 0.25, and 0.35 during extrusion at deformation rates of V=20, 40, 60, and 80 mm/sec was analyzed. The dependence of the extrusion forces of semi-finished products on the displacement of the deforming tool was determined. The extrusion force from the round cross-sectional workpieces is less than the extrusion force from the square cross-sectional workpieces. An analysis of the distribution of specific forces on the deforming tool in terms of normal stresses on the contacting surfaces was performed. The shapes and sizes of semi-finished products with distributions of temperature, stresses, and strains in the deformed metal at the end of extrusion were determined. The cooling of metal layers of semi-finished products near the surfaces with a deforming tool was revealed. The development of the metal structure by hot plastic deformation was evaluated by the distributions of strain intensity in the volumes of the semi-finished products. The use of square-section billets during extrusion leads to an increase in the development of the metal structure along the height of the walls and bottom parts of semi-finished products