Effects of Rotational Feed Emulating Four-Die Radial Forging on Forged Shape in Mandrel-Less Incremental Forging of Thick Circular Tube

Abstract

Tubes with variable wall thickness corresponded to their load distribution have advantages in weightsaving and resource-saving. Because of the advantages, those tubes are applied to bicycles frame and proposed to apply automotive driveshafts [1] and railway axles [2]. Those tubes should be tailormade to reduce their weight effectively; therefore, flexible forming is suitable for their production. Most tubes with variable wall thickness are produced by radial forging, rotary swaging, cross-wedge rolling, and drawing. Those forming processes are relatively flexible; however, their dies and mandrels have to be prepared according to the tubes' size to be produced.The author proposed a new incremental forging to produce tubes with variable wall thickness [3]. A circular tube is placed between two simple flat dies and held by a manipulator. No mandrels are used. Initially, the tube is compressed by the dies in the radial direction. Then, the tube is rotated by the manipulator around the longitudinal direction. After that, the compression and rotation are repeated alternately until an intended forging number. This incremental forging does not require preparing special dies and mandrels regardless of the tubes' size to be produced.One of the difficulties in the proposed incremental forging is to obtain the forming conditions to produce desired shapes because the tube freely deforms except a small area where the two flat dies are contacted. To examine the possibility of formability improvement, the author conducted finite element simulation using commercial software FORGE. As a fundamental research, the effects of rotational feed emulating four-die radial forging on forged shape ware clarified in this study.

A Study on the Effect of the Die Transverse Angle and the Part Rotational Feed Angle in the Cold Radial Forging Process of Rods

“…Diagrams of von Mises, hoop and axial residual stress distribution in the part surface are shown in Figures (19) , respectively.…”

“…Yang et al [18] employed a two-dimensional polycrystalline finite element model to simulate the microstructure and the texture of the 30SiMn2MoVA steel gun barrel processed by radial forging. Makiyama [19] conducted a finite element simulation using commercial software FORGE to study the effect of rotational feed emulating four-die radial forging on the forged shape in mandrel-less incremental forging of thick circular tube. Darki and Raskatov [20] developed a 3D visco-elastoplastic finite element model to predict the effect of the die angle on the forging load and the residual stresses in the workpiece.…”