Internal Flow-Turning – extended manufacturing possibilities in tailored tube production

Abstract

The motivation behind the development of a new approach to the manufacture of tailored tubes is the need for greater flexibility in the wall thickness variation of semi-finished parts compared with present manufacturing processes. In the so-called Internal Flow-Turning (IFT) process, the wall thickness contour of regular tubes with a uniform wall thickness is adjusted by means of a rolling process employing an innovative roller tool on the inside of the tube and a die on the outside of the tube. The gap between the roller element and the die can be adjusted through the axial infeed of the roller tool. The gap defines the current wall thickness of the tube during the manufacturing process. In this way, the wall thickness contour can be set in a precise manner by varying the gap distance as the tube is being pulled through the die. Besides the possibility of locally adjusting the wall thickness, IFT can also be used to form geometrical rib elements in the radial tube direction by using a radially shaped die. As the material flow in the IFT-process is mainly caused by compressive stress, the grooves of the die can be “filled up” by radial material displacement.