Experimental Study of Steady-State Tube Expansion by using Conical Mandrel

Abstract

An Experimental study Conducted for the continuous expansion process of the brass (70/30) tubes by pushing a conical rigid mandrel inside the tube mechanically. This study included an empirical part throughout the test of (60) tube samples to give a different expanding ratios up to (40%) and almost at semi-cone angle of the mandrel ranging from small, medium and large angles (10°,20° and 30°) in addition to that the samples with different relative thicknesses (0.05, 0.1, 0.15 and 0.2).The theoretical part ensures that for the predicted with relative forming stress that needed to complete the expansion process in addition to the changes in the stresses of the various exposed a wall of the sample tube ,The study included the influence of work hardening property which earns this study has a great importance in how to deal with this property. This study showed a good agreement between both theoretical and practical parts, especially in determining the relative forming stress necessary for the success of the operation that showed the relative forming stress increases as the expansion ratio and the semi-cone angle of the mandrel increases has ranged between (0.1-0.7) of the samples tested. Noting that the formation is influenced by the first was much larger than the second was. Whereas the relative forming stress decrease as the relative thickness increase for the same expansion ratio and the semi-cone angle of the mandrel formation.