Cold Metal Forming of Columns with the Rectangular Cross-section Using the Circular Tubes

Cold Metal Forming of Columns with the Rectangular Cross-section Using the Circular Tubes

This article investigates a new method of cold metal forming of columns with rectangular crosssection using the circular tubes under the lateral loading by a U-shaped rigid die in two conditions: empty and polyurethane foam-filled by the experimental methods. During the experiments, the circular metal tubes are compressed between a rigid cubic punch and a U-shaped rigid die in the quasi-static condition to form the tubes into the rectangular columns. Some geometrical groups of the circular specimens were prepared and tested in empty and foam-filled conditions. The specimens were arranged in three different diameters, two different wall thicknesses and four different lengths. Also, for each geometrical characteristic, two other specimens were prepared and filled by the foam with two different densities. Effects of foam-filler, foam density, tube wall thickness, tube length and diameter are investigated on the cold forming process of rectangular columns. The experiments show that in most of the empty samples, an undesirable extra plastic hinge line is created during the forming process, but, this phenomenon is not observed in the filled specimens. Therefore, the experiments illustrate that filling the tubes by the polyurethane foam improves the deformation mode and final shape of the product comparing with the desirable form. Also, it is found that the final shape of the rectangular columns improves by decreasing initial tube diameter and wall thickness, but it is independent of tube length. The tests show that the required mean load of the process increases by increasing the wall thickness, tube length and foam density, and by decreasing the tube diameter.