Effect of Cooling on Bending Angle and Microstructure in Laser Tube Bending with Circumferential Scanning

Laser tube bending is a flexible forming process. Two irradiation methods of axial and circumferential scanning are generally used to form metal tubes. The two most important disadvantages of circumferential scanning are its lower bending angle and the time interval required between each scan for cooling purpose. In this research, a novel cooling strategy during laser tube bending with circumferential scanning is proposed to eliminate these disadvantages. The effects of this method on the bending angle and total production time are experimentally investigated. Also, the changes in the microstructure of the tube after bending are studied. The bending angle obtained at each scan using this strategy was increased more than 1.5 times with much less production time and energy consumption. Besides, the undesired effect of HAZ was significantly reduced. It is shown that this new cooling technique can highly improve the efficiency of laser tube bending by the circumferential scanning method.