Manufacturing Technology Today

N. S. Das ¹, S. K. Sahoo ¹

Affiliations
1 Department of Mechanical Engineering, National Institute of Technology, Rourkela, 769 008, IN

Abstract

In the present investigation a class of upper bound solutions are proposed for plane-strain extrusion through square dies at different area reductions. The variation of normalized mean extrusion pressure with area reduction has been computed for a number of die geometries and for different values of friction conditions at the interfaces. A non-linear optimization procedure for calculation of the best upper bound is used. The method eliminates the constraints by a simple change of variables thus transforming the usual constrained problem to an unconstrained problem so that more complex velocity fields may be analyzed by the proposed procedure. The results are compared with slipline field analysis.

Full Text

     

N. S. Das ¹, S. K. Sahoo ¹

Affiliations
1 Department of Mechanical Engineering, National Institute of Technology, Rourkela, 769 008, IN

Abstract

In the present investigation, experimental studies were carried out with a view to compare some theoretically predicted plane-strain extrusion loads with experiment, taking into account friction at the billet-die and billet-container interfaces. The study was confined to square dies only and a laboratory extrusion apparatus was used for the purpose with lead as the work material.

Full Text

     

S. K. Sahoo ¹, N. S. Das ¹

Affiliations
1 Department of Mechanical Engineering, Eegional Engineering College, Rourkela-769 008, IN

Abstract

We know that it is very difficult to get exact mathematical solution for metal forming problems, hence a number of approximate methods are used. Upper bound method is always preferred for the analysis of metal forming problems as it ensures the metal flow. But till date no attempt has been made to find the upper bound solution of a truncated cone. In the present work a generalized expression for finding out the average forging pressure in case of axisymmetric forging (cold) of a truncated cone is found out considering an exponential velocity field taking account the bulging effect. The effects of taper angle, height and friction on forging load are studied.

Full Text