Laser forming of a dome shaped surface: Experimental investigations, statistical analysis and neural network modeling

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Forming a 3D shape from a flat sheet metal using a laser beam requires multiple irradiations along different paths with necessary heating parameters. In this article, investigations on forming a dome shaped surface from a square metal sheet were carried out using laser forming under temperature gradient mechanism. Experiments were conducted to study the effects of various process parameters, considering laser power, scan speed and spot diameter as inputs and the dome height as the output. Statistical regression analysis was performed based on the experimental data collected according to a design of experiments. All the input variables were found to have significant effects on the dome height. Dome height increased with the laser power and decreased with the spot diameter, but it was found to initially increase and then decrease with the scan speed. Optimization was done to obtain the maximum dome height and the corresponding set of optimal input parameters. Neural network-based models were also developed to predict the dome height and carry out the process synthesis, i.e., to predict the process parameters for obtaining a particular dome height. These methods were able to predict the dome height and process parameters with reasonable accuracy. The effects of sample size, scan pitch, number of scans and Fourier number on dome height were further investigated experimentally. The dome height was found to increase with the increase of work piece size and number of laser scans, and decrease with the scan pitch and Fourier number.