Experimental investigation of hydrodynamics of melt layer during laser cutting of steel

Abstract

is an open access repository that collects the work of Arts et Métiers ParisTech researchers and makes it freely available over the web where possible. Abstract. In laser cutting process, understanding of hydrodynamics of melt layer is significant, because it is an important factor which controls the final quality. In this work, we observed hydrodynamics of melt layer on kerf front in the case of laser cutting of steel with inert gas. The observation shows that the melt flow on the kerf front exhibits strong instability, depending on cutting velocity. In intermediate range of velocity, the flow on the central part of the kerf front is continuous, whereas the flow along the sides is discontinuous. It is firstly confirmed that the instability in the side flow is the cause of the striation initiation from the top part of the kerf. The origin of the instability is discussed in terms of instabilities in thermal dynamics and hydrodynamics. The proposed model shows reasonable agreement with experimental results.

Numerical investigations on high-power laser cutting of metals

“…The model involves the implementation of a local absorbed laser intensity depending on the tilt angle. At low cutting speeds, the shelf structure formation is obtained by using our model, in accordance with the experimental observations of Hirano and Fabbro [22], and as predicted by Golubev [15]. The main data used in the simulation concern the temperature-dependent physical properties of the workpiece, the laser beam parameters, and the surrounding air conditions.…”

“…The images shown in the right side of Fig. 8 are reported by Hirano and Fabbro [22] from their experiments.…”

“…In order to compare our numerical modeling results to the experimental observations, we have used operating parameters similar to those used in the experimental work performed by Hirano and Fabbro [22]. The laser parameters, the workpiece, the assist gas characteristics, and the ambient operating conditions are as follows:…”

“…• In order to compare with the set of experimental results given in Hirano and Fabbro [22], the parametric study concerns cutting speeds from 1 to 6 m/min.…”

“…For the assumed experimental data of Hirano and Fabbro [22] used as operating parameters in our modeling, a Newtonian and laminar flow involving a free surface deformation is considered for the liquid metal. A model is developed to solve the set of hydrodynamic equations which govern the melt film dynamics during the interaction with the absorbed laser beam and the gas jet, under normal atmospheric conditions.…”