Numerical simulation of thermohydraulic characteristics of dross ejection process in laser steel cutting

Sugihara, Kenta ; Nakamura, Yasuyuki ; Ogawa, Takemitsu; Muramatsu, Toshiharu

Numerical simulation code, based on multi-phase thermohydraulics, has been being developed with a goal of a control and prediction for the laser cutting process. A thermohydraulic numerical simulation of the laser steel cutting was carried out to confirm an assist gas and sweep velocity effect to the cutting performance. The performance was evaluated, based on temperature profile and cutting front formation. Simulation results were as follows. If there was no effect of dross ejection by assist gas, a laser light was absorbed into molten steel stagnated in the kerf. Therefore, there was less laser heat input to a solid surface directly. Then, heat transport to the back side of steel plate got delayed. In the case of faster sweep velocity, delay of heat conduction and failure cut were confirmed at behind the cut starting position of the steel plate. Failure cut at the position was observed in our experiments. From these results, it was concluded that the thermohydraulics in the kerf takes important role for not only dross ejection but also promotion of heat input at solid surface.