Laser machining apparatus and laser machining method for performing laser machining while controlling reflected light

A laser machining method executed in a laser machining apparatus that outputs a laser beam from a cutting head to a workpiece and performs laser machining while controlling reflected light of the output laser beam, the laser machining method comprising the steps of:

• outputting the laser beam to the workpiece for a setting time at a laser power low enough not to melt or oxidize the workpiece to measure reflected light of the output laser beam before performing laser machining on the workpiece;
• comparing a measured value of the reflected light to a predetermined reference value, wherein the predetermined reference value is based on a type of the workpiece, and is associated with a laser power suitable for melting or oxidizing the workpiece;
• selecting the laser power suitable for melting or oxidizing the workpiece associated with the predetermined reference value based on the comparison;
• determining whether or not the workpiece can be melted or oxidized based on the selected laser power suitable for melting or oxidizing the workpiece;
• when the determining indicates that the workpiece can be melted or oxidized, outputting a laser beam to the workpiece for a setting time at a laser power high enough to melt or oxidize the workpiece;
• outputting again a laser beam to the workpiece for a setting time at the low laser power to measure reflected light of the output laser beam;
• and
• checking whether or not the workpiece has been melted or oxidized based on a measured value of the reflected light to determine whether or not to start the laser machining.