Experimental study on cold metal shaping of circular tube into a structural profile and analytical calculation of its forming energy

Abstract

This paper introduces a new method on cold metal forming of a circular metal tube into a structural profile and analyzes the process by theoretical and experimental methods. For this purpose, some thin-walled circular tubes of brass are laterally compressed on a U-shaped die with the quasi-static condition in two different conditions of empty and filled by polyethylene Teflon. A theoretical plastic deformation model is introduced, and an analytical relation is derived to predict required energy for performing the shaping process. To perform the experimental investigations, several specimens with different geometrical shapes and initial lengths of the Teflon filler and with different wall thicknesses, lengths, and diameters of circular tubes are prepared to study influences of each parameter on the forming process. Some deviation parameters are defined to check final cross-sectional shape of final productions. The cold forming process is performed by two different methods: single-stage and double-stage process. To investigate verity of the present theory, diagrams of forming energy-lateral displacement are compared with the corresponding theoretical predictions. The performed comparisons show that the theoretical relation estimates forming energy with a good accuracy. Finally, as an application, the produced thin-walled profiles are compressed between two rigid platens in the lateral direction and their energy absorption capacities are compared with the corresponding values of the simple circular tubes. The compared results show that when a circular metal tube is shaped into the structural profile, a new energy absorber part with higher energy absorption capability is achieved.