| 摘要 |
PURPOSE:To prevent the self-combustion of a member at the start point for cutting and to place the start point for cutting on the locus for the necessary cutting shape by forming a laser beam into pulses at the start point for cutting and making the average intensity thereof smaller than the intensity in the stage of cutting. CONSTITUTION:While a laser beam 1 is irradiated to the start point for cutting, the relative position of a working member 3 and the beam 1 is fixed during the prescribed time T1. The beam 1 is made into pulses during this time. The member is worked by the continuous beam at the same laser intensity as the peak of the pulse output upon lapse of the time T1. Since the heated cutting powder material 2 falls from the rear side of the surface irradiated by the beam 1, no excess heat is left in the member 3. On the other hand, the material 2 is not removed at the start point for cutting and the heat input of the beam 1 is left as it is in the member 3 and therefore when the member 3 is locally heated to the specified heat input or above, the member 3 itself burns but the combustion is prevented by making the beam 1 into pulses. |
