Laser machining apparatus and method of setting focus thereof

摘要

The focus of a laser machining apparatus is set by reading a program for setting the focus of the laser beam on a workpiece; irradiating the workpiece with the laser beam according to the program for setting the focus; moving a machining lens relative to the workpiece while keeping constant the distance between the machining head and the surface of the workpiece; detecting information regarding the relative distance between the machining lens and the workpiece; judging that the laser beam has focused on the workpiece when the detected relative distance information has exceeded a predetermined range and when a blue flame occurs; and storing the position information of the machining lens at the time when it is judged that the laser beam has focused on the workpiece.