International Journal of Scientific & Engineering Research, Volume 5, Issue 10, October-2014 78 ISSN 2229-5518 IJSER © 2014 http://www.ijser.org WIRE DRAWING IN DIE-LESS CONICAL PRESSURE UNIT Dr. Yassr Y. Kahtan, Asst. Prof. Talal Y. M. Al-Naib Abstract— A theoretical study of the die-less wire drawing was carried out in which the conventional die is replaced by a die-less conical orifice reduction unit. The process involves pulling the wire through the conical die-less unit which is filled with a polymer melt, the pulling action causes yielding of the continuum and a reduction in area is then obtained. A Newtonian behavior of the polymer melt and a rigid non-linear strain-hardening continuum were considered in which non-linear equations are formulated for the pressure and the stress increment in the die unit. A finite difference numerical technique was applied to solve these equations for the plasto-hydrodynamic pressure and the stress, which enabled prediction of the non-linear deformation profile of the continuum, the pressure distribution, and the percentage reduction in area for various drawing speeds. The maximum reduction in area for wire drawing is (5.5%). The maximum pressure lies in the rear half of the die unit for various drawing speeds and it was found to be larger than that obtained by previous experimental work, however the drawing stress attained in this technique was less than that obtained using conventional dies. Index Terms— Wire Drawing, Die-less, Hydrodynamic Pressure. ——————————  —————————— 1 INTRODUCTION Wire drawing operation involves pulling metal through a die by means of a tensile force applied to the exit side of the die. The material within the die is rendered plastic by the combined action of the applied longitudinal pull and the pressure developed between the wire and the die [1]. The reduction in diameter of a solid bar or rod by successive drawing is known as bar, rod, or wire drawing, depending on the diameter of the final product. In addition to direct application such as electrical wiring, wire is the starting material for many products including wire frame structures (ranging from coat hangers to shopping carts), nails, screws, bolts, rivets, wire fencing, etc. In this technique, the wire is pulled through a tubular orifice of conical or stepped bore shape, which is filled with viscous fluid as shown in figure (1). Experiments [2] have shown that products having comparable dimensional and surface qualities can be achieved using this method. The only limitation observed during this process was the decrease in the reduction of the wire diameter at higher drawing speeds [3]. 2 THEORETICAL ANALYSIS This study is focused on die-less wire drawing, the pressure medium is considered Newtonian. Non-linear equations are formulated for the pressure and axial stress increment in a conical tubular orifice with viscous fluid through which a circular cross-section continuum is being pulled. A finite difference numerical technique was applied to solve these equations for the plasto-hydrodynamic pressure and the resulting axial stress, which in turn enabled prediction of the non-linear deformation profile of the continuum, the pressure distribution and the percentage reduction in area for various drawing speeds. mechanism that can perform planar biaxial loading, the composite materials laminates, preparation of the required specimens, investigation of their mechanical properties, fatigue behavior under uniaxial and plane biaxial loading. There is no standard shape or design for the biaxial specimens until now [4], so the specimen design was based on the generic form shown in fig (1), with specimen arms all of the same length and a circular central gauge section. 2.1 ANALYSIS PRIOR TO THE DEFORMATION OF DIE-LESS WIRE DRAWING PROCESS Figure (2) shows the geometrical configuration of the orifice and the continuum, the gap at any point is given by: kx h h − = 1 (1) Where, B h h k / ) ( 2 1 − = k = is the slope of the die. IJSER