| 摘要 |
PURPOSE:To enhance productivity by irradiating a workpiece with a laser beam, detecting the quantity of light having a wave length different from that of the laser beam produced by the irradiation and thereby accurately discriminating the completion of piercing. CONSTITUTION:Piercing is performed on a workpiece by a laser beam 2 which is outputted from a laser generator 1, reflected with a reflecting mirror 3, transmitted with a semi-transparent mirror 4 and converged with a machining lens 5. A reflected light 7 from the workpiece is reflected by the workpiece, and reflected by the semi-transparent mirror 4, with its quantity of light detected at a means 8 for detecting quantity of light. A wave form is subjected to sample-and-hold by a sampling hold circuit 12 from the quantity of light detected by the detecting means 8 at a timing delayed from the command signal for a laser pulse oscillation; and the detected quantity of light is obtained at the unirradiation time of the laser beam 2. When this value is discriminated as smaller than a threshold value level preliminarily set, piercing is judged as completed. |
