Developing a Support Vector Regression (SVR) Model for Prediction of Main and Lateral Bending Angles in Laser Tube Bending Process

The laser tube bending process (LTBP) is a new and powerful manufacturing method for bending tubes more accurately and economically by eliminating the bending die. The irradiated laser beam creates a local plastic deformation area, and the bending of the tube occurs depending on the magnitude of the heat absorbed by the tube and its material characteristics. The main bending angle and lateral bending angle are the output variables of the LTBP. In this study, the output variables are predicted by support vector regression (SVR) modeling, which is an effective methodology in machine learning. The SVR input data is provided by performing 92 experimental tests determined by the design of the experimental techniques. The measurement results are divided into two sub-datasets: 70% for the training dataset, and 30% for the testing dataset. The inputs of the SVR model are process parameters, which can be listed as the laser power, laser beam diameter, scanning speed, irradiation length, irradiation scheme, and the number of irradiations. Two SVR models are developed for the prediction of the output variables separately. The SVR predictor achieved a mean absolute error of 0.021/0.003, a mean absolute percentage error of 1.485/1.849, a root mean square error of 0.039/0.005, and a determination factor of 93.5/90.8% for the main/lateral bending angle. Accordingly, the SVR models prove the possibility of applying SVR to the prediction of the main bending angle and lateral bending angle in LTBP with quite an acceptable accuracy

Fabrication of Saddle-Shaped Surfaces by a Laser Forming Process: An Experimental and Statistical Investigation

Laser forming is a powerful tool for fabricating complicated shapes economically. The pattern of laser movement (irradiating scheme) has an essential effect on the shaped form. In this article, the forming of a saddle-shaped surface will be investigated experimentally by the laser forming process. A spiral irradiating scheme is implemented to manufacture a saddle-shaped surface. The main idea of this study is the investigation of the simultaneous variations of the process parameters and their effect on the curvature of the final part. The process parameters of the study are the spiral pitch, number of spiral passes, and movement pattern (In-to-Out or reversely Out-to-In scanning path). The response surface methodology is selected for experimentation. The measurement of the deformation results shows that the deformations of laser-formed saddle-shaped surfaces decrease with an increase in the spiral pitch of the path. Additionally, the deformations of the saddle-shaped surface increase by increasing the number of spiral passes. The results demonstrate that the pattern movement has little effect on the deformations of laser-formed saddle-shaped surfaces and an Out-to-In spiral pattern movement is advised. At last, the proper input variables to obtain the maximum value of displacements for the saddle point are determined (10 mm spiral pitch, three spiral passes, and Out-to-In pattern movement)

Comprehensive assessment of laser tube bending process by response surface methodology

The laser beam can be used as a powerful tool for bending tubes and sheets by local heating and buckling mechanism. In this paper, the bending of mild steel tubes will be investigated by irradiation of the laser beam. To consider the effect of the interaction of process parameters despite previous research, six laser tube bending process parameters in different levels including laser power, scanning speed, laser beam diameter, irradiation length, number of irradiation passes, and irradiation scheme are selected and set of 92 experimental tests planned according to the response surface methodology (RSM). The tests have been carried out by using a continuous wave (CW) CO2 laser. The influencing parameters affecting the main bending angle and lateral bending angle are determined. The effect of main process parameters and their interaction on the main and lateral bending angle are discussed either. The AIS creates a higher main bending angle compared to the CIS. The results show that the main bending angle and lateral bending angle increase by increasing the laser power, irradiation length, and the number of irradiation passes and reducing the scanning speed and laser beam diameter. The main and lateral bending angles are determined by a regression equation with about 96% goodness of fitting. The results show that 1100 W laser power, 14.6 mm/s scanning speed, 4 mm laser beam diameter, 28.27 mm irradiation length, 1 pass of irradiation, and axial irradiation scheme (AIS) lead to a simultaneous maximum bending angle of 1.80° and minimum lateral bending angle of 0.152°.publishe

Experimental investigation of laser cladding of H13 hot work steel by Stellite 6 powder

Cladding of metals can enhance the wear behavior of metals. Many dies work at elevated temperature such as hot forging dies and hot extrusion dies need resistance to wear at higher temperatures. In this article, the cladding of H13 hot work steel (DIN 1.2324) was investigated by laser cladding. The Stellite 6 powders coat the steel surface by using a continuous fiber laser. Two important objects in cladding are the effect of laser process parameters on the quality of the cladding layer and the lateral overlapping percent in adjacent passes. The laser power, scanning speed, and powder feed rate are the process variables in the study. The results show that the laser power is the most influencing parameter and by increasing laser power and decreasing the scanning speed, the hardness and penetration depth of cladded powder in the substrate will be increased. The dilution factor increases by increasing the laser power and reducing scanning speed at a moderate powder feed rate. The microstructure observation shows that strong metallurgical bonding between the clad and substrate and good mixing of powder in substrate metal can be obtained by proper setting of process parameters. The micro-hardness of the cladded specimen increased to 300 HV (164% increase compared to the substrate material. Best results were obtained at 10% overlapping between adjacent irradiation passes

Experimental investigation of laser cladding of H13 hot work steel by Stellite 6 powder

Cladding of metals can enhance the wear behavior of metals. Many dies work at elevated temperature such as hot forging dies and hot extrusion dies need resistance to wear at higher temperatures. In this article, the cladding of H13 hot work steel (DIN 1.2324) was investigated by laser cladding. The Stellite 6 powders coat the steel surface by using a continuous fiber laser. Two important objects in cladding are the effect of laser process parameters on the quality of the cladding layer and the lateral overlapping percent in adjacent passes. The laser power, scanning speed, and powder feed rate are the process variables in the study. The results show that the laser power is the most influencing parameter and by increasing laser power and decreasing the scanning speed, the hardness and penetration depth of cladded powder in the substrate will be increased. The dilution factor increases by increasing the laser power and reducing scanning speed at a moderate powder feed rate. The microstructure observation shows that strong metallurgical bonding between the clad and substrate and good mixing of powder in substrate metal can be obtained by proper setting of process parameters. The micro-hardness of the cladded specimen increased to 300 HV (164% increase compared to the substrate material. Best results were obtained at 10% overlapping between adjacent irradiation passes