Method for correcting a predetermined cutting path for cutting a sheet metal blank

A method for cutting a metal blank from a metal strip continuously transported in a transport direction x, comprising:

• preparing a laser cutting apparatus comprising at least one laser moving in a transport direction x and in a transverse direction y running perpendicular to the transport direction x, and a computer storing cutting path coordinates describing a predetermined cutting path for moving the at least one laser;
• simultaneously determining a first x coordinate x1 and a first y coordinate y1 of an arbitrary point (P) of a surface of the metal strip with respect to an x and a y reference, the arbitrary point not being a separate mark put on the metal strip, this determination being done by means of a strip flow measuring device (BF), which allows a determination of positional coordinates xy of the point and their change over time or travel;
• simultaneously determining a second x coordinate x2 and a second y coordinate y2 of the point (P) of the surface of the metal strip with respect to the x and y reference by means of the strip flow measuring device (BF), if the metal strip has been moved in the transport direction x by a predetermined third distance dx3;
• determining a third y correction value Ky3 using a vector (V) determined by the strip flow measuring device (BF) from coordinate pairs (x1, y1) and (x2, y2);
• using the third y correction value Ky3 to correct cutting path coordinates describing the predetermined cutting path;
• and
• cutting the metal blank by moving the at least one laser along the predetermined cutting path corrected by the third correction value Ky3 while the metal strip is continuously transported in the transport direction x.