Study on the Influence of the Preheating Flame Characteristics and the Oxy-fuel Gas Cutting Performance

Abstract

To study the influence of the CO₂ on the cutting performance, the heat input due to preheating flame q_G, and that due to the combustion of the material being cut q_B are estimated by performing a three-dimensional nonlinear heat conduction analysis that considers the temperature dependence of the thermomechanical properties. Spot heating tests are performed to identify the heat input parameters of the preheating gases H₂ and H₂-CO₂. Gas cutting tests are performed to identify the characteristics of the cutting groove shape while employing the selected preheating gases. Based on the information of the spot heating, and the gas cutting tests, a three-dimensional heat conduction analysis is performed to identify the temperature fields along the thickness direction of the workpiece. A new technique for the estimation of the temperature fields considering inclined cutting-fronts based on Matsuyama’s theory is proposed. The role of the preheating heat input and the material combustion heat input for the selected gases is examined. Based on the simulation results of this study, CO₂ deterioration mechanism on the cutting performance is discussed. From the study, the following results were obtained: (1) A new procedure for the kerf temperature estimation throughout the plate thickness based on the two-dimensional analysis of Matsuyama is established. The procedure allows a smooth and continuous temperature distribution through the plate thickness direction. (2) By applying the proposed procedure, it is possible to estimate the three-dimensional kerf temperature distribution on thick plates and allows the consideration of inclined cutting fronts. (3) By evaluating the preheating, and the material combustion heat input, it is observed a substantial declined in q_G when employing CO₂ while q_B remains unchanged regardless of the employed preheating gas.