Laser cutting method

Abstract

A laser cutting method and a laser cutting apparatus cut a metallic work with a laser beam of a one-micrometer waveband. The method and apparatus carry out the laser cutting of the work with a ring beam RB passed through a focus position of a condenser lens 13 and having inner and outer diameters that tend to expand. The outer diameter of the ring beam is in a range of 300 μm (micrometers) to 600 μm, an inner diameter ratio of the same is in a range of 30% to 70%, and a focal depth of the condenser lens is in a range of 2 mm to 5 mm.

1 . A laser cutting method of cutting a work with a laser beam that becomes a ring beam whose inner and outer diameters gradually expand after passing a focus position of a condenser lens arranged in a laser processing head, the laser beam including a first portion in a region extending between the condenser lens and the focus position of the condenser lens, the first portion of the laser beam extends continuously within an area defined by and entirely filling a perimeter of the first portion of the laser beam, the perimeter of the first portion of the laser beam is defined by a diameter of the first portion of the laser beam; and the ring beam comprising a second portion of the laser beam, the ring beam of the second portion of the laser beam extending within an area defined between the outer diameter of the ring beam and the inner diameter of the ring beam, the method comprising:
 providing the laser beam;   applying the first portion of the laser beam to a surface of the work to carry out a piercing process; and   thereafter, applying the ring beam of the second portion of the laser beam to the surface of the work to perform the cutting of the work.   
     
     
         2 . The laser cutting method according to  claim 1 , wherein after the piercing process, the applying of the ring beam to the surface of the work includes:
 moving a laser processing head toward the surface of the work; and   thereafter, moving the laser processing head in a direction along the surface of the work.