Forming box-shaped ends in circular tubes

This study is aimed to form a pair of axially displaced box-shaped ends from a circular tube. In this process, one tube end is first expanded into a circular section having a diameter equal to the diagonal length of the target square using a conical top circular die. A square punch having a conical bottom end and a tapered square die are then used to draw the expanded section into a square box. The side walls of the box are flattened at an ironing ratio of 15% corresponding to its initial wall thickness. The expansion and squaring processes are repeated at the opposite tube end. However, the tapered die in the final stage is oriented at 45 relative to the square punch and tube to form an axially displaced square section at the opposite end. Both the experiments and FE simulations were performed to evaluate this process. A pair of axially displaced box-shaped ends having small corner radii is successfully obtained from the experiment and the simulation. With the developed process, the design of steel balustrades is improved and similar to the precast or stone balustrades.