Stainless steel 3D laser forming for rapid prototyping

Abstract

Laser forming is well known for allowing hard tool-less forming procedures, which produce precise metal sheet products. This is due to the fact that deformations are springback-free since they are induced by thermal variation inside the sheet, which are generated by laser irradiation. The basic mechanism is based on a thermal-induced deformation and it is not yet possible to adequately control it.Nowadays, the generation of complex curved sheet metal parts for rapid prototyping is possible using only curved irradiation, i.e. the irradiated path on the surface is curved. The forming mechanism induced by this irradiation strategy is similar to those of linear irradiation, i.e. the irradiated path on the surface is straight, but their effects are averagely lower.In this paper, the effect of curved irradiation was investigated for AISI 316 and AISI 304 stainless steel sheets by numerical and experimental analysis. The experimental analysis was design according to the Design of Experiments Analysis (DOE) principles. This permits to evaluate the effects of process parameters on the bending angle on the basis of a statistical analysis. In fact, the analysis of variance was performed. It gave the weights of every single studied variables on the deformation process. Thereafter, the levels of the parameters, which gave the largest deformation, were isolated by means of Response Surface Method (RSM).The investigated parameters were the spot diameter, the curvature and the length of irradiation path, the laser power and speed. A CO2 operating in continuous wave regime laser source was used. All the tests were performed and compared on the basis of geometrical and technological parameters. The results were also compared with those of linear irradiation, which were gathered during previous investigations.Moreover, the collected experimental data were interpolated by means of an Artificial Neural Network (ANN), which are well known as universal interpolators.In the view of the exploitation of laser for forming in the mechanical engineering, this investigation provided a better knowledge of the process and demonstrated the effectiveness of DOE for optimal process parameters selection and ANN for experimental data interpolation.Laser forming is well known for allowing hard tool-less forming procedures, which produce precise metal sheet products. This is due to the fact that deformations are springback-free since they are induced by thermal variation inside the sheet, which are generated by laser irradiation. The basic mechanism is based on a thermal-induced deformation and it is not yet possible to adequately control it.Nowadays, the generation of complex curved sheet metal parts for rapid prototyping is possible using only curved irradiation, i.e. the irradiated path on the surface is curved. The forming mechanism induced by this irradiation strategy is similar to those of linear irradiation, i.e. the irradiated path on the surface is straight, but their effects are averagely lower.In this paper, the effect of curved irradiation was investigated for AISI 316 and AISI 304 stainless steel sheets by numerical and experimental analysis. The experimental analysis was design according to the Design of Experiments Analysis (DOE) princ...