Influence of Projection Number of Circular Tube with Many Spiral Projections on Inside Wall Formed by Extrusion

Abstract

Extrusion components are used in many industrial systems, such as railroad vehicles and heat exchangers. The demand for components whose section and tube are not uniform is increasing, and there are several studies of nonuniform tubes. A typical extrusion study involves a tube with spiral projections on the inside wall. When the tubes are exchangers, such as in room air conditioners, they raise the heat exchange performance. If the exchanger tube are made of extruded aluminum, spiral projections formed on the inside wall can extend the limit of the exchanger. The exchanger tubes will become inexpensive and the productivity will be improved. We propose a new extrusion method for tubes with spiral projections on the inside wall in this study. The new extrusion method is suitable for mass production, and the setup spiral angle of projections is 30 degrees. The material flow of a billet is changed by the mandrel slots and the tubes with spiral projections on the inside wall are made. The extrusion conditions were experimentally discussed regarding the shape of circular tubes with spiral projections. We experimentally clarified the limit and characteristics of the extrusion of circular tubes with spiral projections on the inside wall in this study.