JPS6434589A - Method for controlling laser beam output of laser beam machine - Google Patents

Abstract

PURPOSE:To form a crater with an uniform shape all over the surface of a work by measuring a formed crater diameter by a laser beam for measuring and controlling a power unit so as to attain the target crater diameter at the time of forming the crater on the work surface by the laser beam. CONSTITUTION:A rolling roll 1 is rotated in the arrow F direction at a prescribed speed to form the crater 1a by the laser beam 17 from a laser been oscillator 7. At this time, the laser beam (a) for measuring is separated from the laser beam 17 by a spectroscope 23 and projected on the surface whose machining is finished at an incident angle theta to detect the reflected beam (b) by a photodetector 19. The photodetector 19 outputs an electrical signal (c) with the size in proportion to the quantity of photodetection to a limitter 20 which cuts the small signal of the output signal and outputs a signal (d) more than a prescribed value to a timer 21. The timer 21 measures the time when a signal is not outputted from the timer 21 based on the signal (d) and inputs a signal (e) to a computing element 22 and calculates the size of the crater 1a here and compares it with a target value (s) and outputs a signal (f) to the electric power unit 18 to carry out the control.