ALTERNATIVE STUDY OF A BEVEL PUNCH-ASSISTED ECAE SCHEME

Alexander V Perig,Nikolai N Golodenko

doi:10.12776/ams.v24i4.1147

Abstract

It is a common practice in pressure forming to make an Equal Channel Angular Extrusion (ECAE) of a workpiece through a die with channel intersection angle 2θ = 90° using a standard punch of brick or cylindrical shape with 2θ0 = 90°. However Nejadseyfi et al (2015) have applied a beveled 2θ0-punch to the process of ECAE through a standard angular die of Segal geometry with 2θ = 90° and 2θ0 ≠ 2θ. The scope of the article is focused on an alternative numerical study of Nejadseyfi-ECAE-Scheme using techniques of Computational Fluid Dynamics (CFD). A finite-difference method was applied to the numerical solution of the boundary value problem for the Navier-Stokes equations in the form of a vorticity transfer equation. The complex of 2D plots for CFD-derived fields of flow lines and flow velocities and 3D plots for spatial distributions of flow velocities and tangential stresses were firstly derived for Nejadseyfi-ECAE-Scheme during viscous flow of polymer workpiece models through angular die with 2θ = 90° for the different punch inclination angles 30° ≤ 2θ0 ≤ 150°. It was found that Nejadseyfi-ECAE-Scheme provides enhancement of the rotary modes of intensive deformations during ECAE. Results provide visualization of velocity gradients and macroscopic rotation and the illustration of Nejadseyfi et al’s ideas from an alternative CFD-based viewpoint.

Highlights

1 Introduction Equal Channel Angular Extrusion (ECAE) or Pressing (ECAP) [1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,31,32,33,34,35,36,37,38,39,40,41,42,43,44,45,46,47,48,49,50,51,52,53,54,55,56,57,58,59,60,61,62,63,64,65,66,67,68,69,70,71,72,73,74,75,76,77,78,79,80,81,82,83,84,85,86,87,88,89,90,91] is a modern material processing technology, which has attracted a lot of research attention from materials science community [1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,31,32,33,34,35,36,37,38,39,40,41,42,43,44,45,46,47,48,49,50,51,52,53,54,55,56,57,58,59,60,61,62,63,64,65,66,67,68,69,70,71,72,73,74,75,76,77,78,79,80,81,82,83,84,85,86,87,88,89,90,91]
Perig et al (2015, 2017) have reported research in the ECAE application of bevel edge 2θ0-punches to an angular extrusion through 2θ-dies (2θ0 = 2θ, 2θ ≠ 90°) in Perig et al’s FEM-based [53], Computational Fluid Dynamics (CFD)-based [54, 60], and circular gridlines-based [61] articles
And simultaneously have appeared an alternative original research article by Nejadseyfi et al (2015-2016), which was focused on the application of an inclined 2θ0-punch to ECAE through an angular die with channel intersection angle with 2θ = 90° and punch inclination angle 2θ0 ≠ 2θ [43,44]

Summary

Introduction

Equal Channel Angular Extrusion (ECAE) or Pressing (ECAP) [1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,31,32,33,34,35,36,37,38,39,40,41,42,43,44,45,46,47,48,49,50,51,52,53,54,55,56,57,58,59,60,61,62,63,64,65,66,67,68,69,70,71,72,73,74,75,76,77,78,79,80,81,82,83,84,85,86,87,88,89,90,91] is a modern material processing technology, which has attracted a lot of research attention from materials science community [1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,31,32,33,34,35,36,37,38,39,40,41,42,43,44,45,46,47,48,49,50,51,52,53,54,55,56,57,58,59,60,61,62,63,64,65,66,67,68,69,70,71,72,73,74,75,76,77,78,79,80,81,82,83,84,85,86,87,88,89,90,91]. Today we know that the development of applications of the bevel edge punch for Equal Channel Angular Extrusion (ECAE) dies originated 30 years ago in Moscow, USSR, 1987 in restricted-access Russian-language research of such scientists as Mikhalevich V.M. Perig et al (2015, 2017) have reported research in the ECAE application of bevel edge 2θ0-punches to an angular extrusion through 2θ-dies (2θ0 = 2θ, 2θ ≠ 90°) in Perig et al’s FEM-based [53], CFD-based [54, 60], and circular gridlines-based [61] articles. And simultaneously have appeared an alternative original research article by Nejadseyfi et al (2015-2016), which was focused on the application of an inclined 2θ0-punch to ECAE through an angular die with channel intersection angle with 2θ = 90° and punch inclination angle 2θ0 ≠ 2θ [43,44]. The purpose of the present research study is to provide an analysis of geometric and energypower parameters of Nejadseyfi et al’s ECAE scheme [43,44] from CFD-based viewpoint [42, 46, 50,51, 54, 56,57,58, 60, 92,93,94,95,96,97,98]

Methods

Results

Discussion

Conclusion