Laser machining apparatus and laser machining method

A laser machining apparatus, comprising:

• a machining head configured to emit a laser beam for cutting sheet metal of stainless steel;
• a moving mechanism configured to move the machining head relatively to a surface of the sheet metal;
• a beam vibrating mechanism configured to vibrate the laser beam in a parallel direction with a cutting advancing direction of the sheet metal when cutting the sheet metal by relatively moving the machining head by the moving mechanism;
• a database configured to store, as a machining condition, a relationship between a moving velocity at a time of relatively moving the machining head by the moving mechanism, and a vibration frequency of the laser beam by the beam vibrating mechanism, the moving velocity and the vibration frequency being obtained in advance for each plate thickness of the sheet metal, cutting of the sheet metal being possible at the moving velocity and the vibration frequency;
• and
• a control device configured to control the moving mechanism to relatively move the machining head at a moving velocity selected based on the machining condition, and control the beam vibrating mechanism to vibrate the laser beam at a vibration frequency selected based on the machining condition,
• wherein in the machining condition, a single specific vibration frequency at which cutting of the sheet metal is possible is set to a maximum moving velocity at which cutting of the sheet metal is possible, and a plurality of vibration frequencies from a maximum frequency to a minimum frequency at which cutting of the sheet metal is possible are set to the moving velocity more than or equal to a minimum moving velocity and less than the maximum moving velocity at which cutting of the sheet metal is possible, and
• the control device controls the beam vibrating mechanism to vibrate the laser beam at the specific vibration frequency when relatively moving the machining head at the maximum moving velocity, and controls the beam vibrating mechanism to vibrate the laser beam at a vibration frequency selected from the plurality of vibration frequencies from the maximum frequency to the minimum frequency, when relatively moving the machining head at any moving velocity more than or equal to the minimum moving velocity and less than the maximum moving velocity.