INCREASE OF PLASTIC DEFORMATION WORKOUT OF WALLS AND BOTTOM PART OF HOLLOW SEMI-FINISHED PRODUCT DURING HOT REVERSE EXTRACTION

Abstract

Computer analysis of the processes of hot reverse extrusion with crushing of round hollow semi-finished products from
cylindrical and square billets made of mild steel by the finite element method using the DEFORM-3D program has been carried
out. The extrusion with crushing provides hollow semi-finished products with external dimensions that are larger than the
dimensions of the billets. The processes of extrusion, removal of punches from the obtained semi-finished products and pushing
of semi-finished products out of dies are considered. The dependences of the forces of such processes on the movement of the
deforming tool have been established. The extrusion force of semi-finished product from round billet is 12% less than the
extrusion force from square billet. Shapes and sizes of semi-finished products with distributions of temperature, stresses and
deformations at the end of extrusion are determined. The elaboration of metal structure by hot plastic deformation is estimated
by the distribution of strain intensity in semi-finished products. The use of a square billet in extrusion leads to an increase in
the elaboration of the metal structure along the wall height by 12% and by 16% at the bottom part of the semi-finished product