Branched tubes are an important component of the piping system. A new incremental burring process for manufacturing branched tubes is developed to enhance the formability, product quality and process flexibility of large branched tubes. A significantly crucial process history using a bar tool is proposed suitably on the basis of features of conventional forming processes. Concerning incremental burring processes, proper forming conditions were decided using FE simulation, as previously reported. In this study, to put a new burring method to practical use, a large branched pipe is studied. In the experiment, the following branched tubes are used: A5083-O, SUS304 and SS400 with diameters of 300 and 400 mm and wall thicknesses of 3.0, 4.0 and 6.0mm. The equipment is remodeled to achieve new processes and a bar tool with diameter of 65 mm is used. The method consists of three stages. The history of thickness reduction ratio distribution is almost the same as that in the analysis. Moreover, the thickness reduction ratio distribution at the edges of the branched tubes is hardly affected by the materials and thicknesses of the work. The results show that branched tube can be burred under a cold condition and its use can flexibly reduce the die cost related to the diameter of the branched tube with a bar tool.
