Effect of Heating Order on Interference between Deformations by Curved Line Heating in Laser Forming

Laser forming is one of a few processing methods that can form a plate material into a curved surface without contact and without using a mold. A combination of multiple curved heating lines is required to form a practical shape. The relationship between heating conditions and deformation has been studied in detail in the field of welding, etc. when the heating line is straight. However, there are not many reports investigating the effect of interference between heating lines on deformation. Therefore, in this study, we investigated the interference effect of multiple heating lines with different heating order on angular distortion in laser forming under different two conditions, straight heating lines and curved heating lines. Annealed austenitic stainless steel sheet material with 0.75mm thick was used as the test material for the laser forming with 1500W YAG laser before deformation measurement by using a non–contact three–dimensional coordinate measuring device. From the relationship between the heating order and the angular distortions of the three heating lines arranged concentrically, the influence of the area inside and outside of the curved heating line on the angular distortion behavior of the other heating lines was investigated. When the heating was repeated inside the curved heating line, the inner heating hardly interfered with the angular deformation of the outer heating line, but the angular distortion on the heating line placed inside was changed. When the heating lines were placed on the outside in order, the amount of angular distortion of the heating lines placed earlier changed depending on the heating lines placed later. When considering the curved heating part by classifying it into the inside and outside of the curve, the ability to interfere with the angular distortion of other heating lines was observed inside, but not outside. When laser forming curved surface using multiple curved heating, it was found that the classification of the inner and outer regions of the curved heating part and the heating order are important for examining the interference between the heating lines. [doi:10.2320/jinstmet.J2020033]