Non-Symmetrical Direct Extrusion-Analytical Modelling, Numerical Simulation and Experiment.

Marek Kowalik,Piotr Paszta,Leon Kukiełka,Tomasz Trzepieciński

doi:10.3390/ma14247856

Abstract

The article presents the original technology of the extrusion of hollow curved pipes. The curvature radius of pipe axis was obtained directly during extrusion by eccentric alignment of the annular calibration gap of the extrusion die. Theoretical relationships describing the radius of curvature of the extruded part as a function of the eccentricity e of position of the annular calibration gap in the die were developed. A die with replaceable inserts with eccentricity e equal to 1, 2, 3, 5, 7 mm was designed and fabricated. Experimental tests were carried out to extrude lead pipes with an outer diameter of 20 mm and an inner diameter of 18 mm. Measurements of the radii of the curvature of the extruded pipes were consistent with the values calculated from the developed theoretical relationships. Numerical modelling of the proposed method of extrusion in a finite element-based QForm 3D program was carried out. The finite element method (FEM) numerical calculations were carried out for lead. Numerical simulations and experimental studies have shown that, by changing the value of the eccentric gap, the radius of curvature of the extruded pipe can be controlled.

Highlights

One of the methods used in the production technology of machine parts, including the production of hollow toric elements, is the direct extrusion of metal elements
The value of the radius Rt of the hollow elements formed by the direct extrusion method from a specific stock is inversely proportional to the value of eccentric e
It has been found that, by using eccentric extrusion, hollow products are obtained, which are distinguished by a uniform fibrous structure of the numerical simulation of the lines of the flow of lead during direct extrusion with an eccentric position of the sizing ring

Summary

Introduction

One of the methods used in the production technology of machine parts, including the production of hollow toric elements, is the direct extrusion of metal elements. Metal flow may be predicted through finite element-based numerical models They described the procedure of designing dies for the extrusion process of complex shapes from aluminium alloys. The method of the direct extrusion of hollow parts with a nonrectilinear profile radius consists in the use of the eccentric positioning of the hole in the die. Due to the eccentric position of the hole in the die bottom, on both sides of the plane of symmetry of the wall-forming gap, a difference in material volumes occurs, while the different material volumes flowing into the ring-shaped gap causes the extruded piece to bend. The shape and dimensions of the jigs were designed depending on the initially assumed sizes of the hollow torus elements for the specified extrusion method and the assumed technological parameters of the process. Yield Stress Re, MPa Ultimate Tensile Stress Rm, MPa Elongation A5, % Young’s Modulus E, MPa Poisson’s Ratio ν

Extrusion Process

Microstructural Examination

Analysis of the State of Stress

Conclusions