Parametric study on bending and thickening in laser forming of a bowl shaped surface

Shaping a circular sheet into a bowl requires in-plane thickening as well as out-of-plane bending. Combinations of radial and circular laser scan paths can make that. In this work, the effects of various process parameters, viz, laser spot diameter, laser power and scan speed, on the in-plane and out-of-plane forming of stainless steel circular blanks were studied for various circular and radial scan schemes. Taguchi method was used to plan the experimental runs. Both bending angle and thickness increment for circular and radial scan schemes, respectively, were found to increase with reducing laser beam diameter and scan speed, and increasing laser power. The experimental results were corroborated with the predictions by simplified analytical models. Further, the bending angle was found to increase with increasing radius of the circular scan path. Increase in the number or in the length of radial scan lines increased the thickness increment and the bending angle, induced due to the resultant shrinkage in the periphery of the blanks. It was found that the combination of radial and circular scan schemes works better for achieving higher bending angle with smaller coefficient of variation, which gives a measure of wrinkling in the formed blanks. (C) 2012 Elsevier Ltd. All rights reserved.