Method and apparatus for laser cutting

A laser cutting method for laser cutting a metallic material workpiece to form a hole in the workpiece, the hole having a desired shape, comprising the steps of:

• cutting said workpiece up to a point a predetermined distance from a cutting end point on a circumference of said hole according to first laser cutting conditions;
• cutting said workpiece between said point a predetermined distance from said cutting end point and said cutting end point according to second laser cutting conditions, said second laser cutting conditions being different from said first laser cutting conditions, wherein at least one of pulse peak output, cutting gas pressure and focus position in said second laser cutting conditions is the same as at least a corresponding one of pulse peak output, cutting gas pressure and focus position in said first laser cutting conditions.

A laser cutting apparatus, comprising:

• means for recognizing the presence of a piercing line in contact with the circumference of a hole to be formed by laser cutting at an arc of 1 mm or more radius (R) on the basis of cutting path information,
• means for determining a point of a circumferential distance approximately 4.times.R short of cutting end point on said hole circumference, said point being a switching point for switching first laser cutting conditions to second laser cutting conditions, and
• means for automatically allocating said first laser cutting conditions and second laser cutting conditions relative to said switching point.

A laser cutting method for laser cutting a metallic material workpiece to form a hole in said workpiece, said hole having a desired shape, comprising the steps of:

• cutting said workpiece up to a point a predetermined distance from a cutting end point on a circumference of said hole according to first laser cutting conditions;
• cutting said workpiece between said point a predetermined distance from said cutting end point and said cutting end point on said circumference of said hole according to second laser cutting conditions such that damage to the workpiece is minimized;
• wherein the laser cutting according to said first laser cutting conditions forms a first groove in said workpiece having a first width, and the laser cutting according to said second laser cutting conditions forms a second groove in said workpiece having a second width, and said second width is substantially the same as said first width.