The effect of beam geometry on stress distribution in laser bending of tubes

Abstract

Laser forming is a spring-back free non-contact forming method. Compared to the mechanical bending no hard tooling, dies or external force is used. Laser forming in recent years have received considerable attention. Within laser forming; tube bending is an important industrial activity, the final product being used in critical engineering systems like heat exchangers, hydraulic systems, boilers etc, etc. Laser tube bending utilizes the thermal stresses generated during laser scanning to achieve the desired bends. The parameters varied to control the process are usually laser power, beam diameter, scanning velocity and number of scans. The thermal stresses generated during laser scanning are strongly dependent upon laser beam geometry. To the best knowledge of authors there are only a small number of publications available on this aspect. Most of these publications have only considered circular and rectangular beams. This paper investigates the effect of laser beam geometry on laser tube bending. Finite element modeling has been used for better understanding of the process. Some of the results have also been validated by experiments