2016 Volume 56 Issue 8 Pages 1452-1461
In this paper processing effects were studied while 12 mm thick circular blanks of hardened-tempered AISI 1040 graded medium carbon steel, applied in cylindrical cup manufacturing by a new modified processing route as an innovative approach. The processing route mainly consisted of pre-forming of flat blanks to a little draw in shape, followed by multistage drawing without blank-holder. The wall ironing was purposefully accompanied with deep drawing by ensuring suitable die-punch design to reduce wall thickness as well as earing tendency on cup edges. Thus, evolution of cup dimensions and quality, wall thickness distribution profiles, drawability and ironability parameters, punch force history, hardness distribution profiles, strain distribution profiles, spring back tendency by Demeri split ring test, and microstructures of cup wall zones were discussed.
With appropriate heat treatment cycle, the steel showed a good combination of strength-ductility-formability and thus indicated its moderate drawability with high strength applications, i.e. up to ~634 MPa. The multistage cup drawing process feasibility was confirmed by manufacturing of >50 mm long cylindrical cups with uniform wall thickness and without any common forming defect. The microstructure study of cup walls also further substantiated the process feasibility. Moreover, the data pertaining to strain distribution profiles and spring back tendency of cups were shown for the process engineers to optimise the process and draw tool design, as a future scope of work.
