Laser cutting nozzle for a laser machining unit and method for operating such a laser machining unit

A method of performing three-dimensional cutting machining on a metal profile, the method comprising:

• feeding a cutting gas to a laser cutting nozzle, the laser cutting nozzle comprising a passage for a laser beam and a cutting gas, the passage extending between a nozzle inlet and a nozzle mouth along a passage longitudinal axis, the passage converging continuously towards the nozzle mouth thereof, in a convergence portion, as far as a constriction of the passage, to less than 40% of a cross-sectional area at an inlet of the convergence portion, the passage diverging continuously in a divergence portion, proceeding from the constriction of the passage, as far as the mouth of the passage, to over 130% of a cross-sectional area at the constriction of the passage, wherein, in the entire divergence portion, the wall of the passage is at an angle of inclination relative to the passage longitudinal axis of at most 5°, and the length of the divergence portion is less than 5 times the diameter of the constriction and more than twice the diameter of the constriction, wherein the cutting gas is fed on the inlet side, at a pressure of between 8 and 23 bar;
• and
• cutting, at least intermittently, the metal profile at a distance between the nozzle and a workpiece surface that is in a distance range of between 2 and 6 mm;
• wherein the metal profile has a workpiece thickness of between 1 to 4 mm.

A laser cutting nozzle for a laser machining unit, the laser cutting nozzle comprising:

• a passage for a laser beam and a cutting gas,
• the passage extending between a nozzle inlet and a nozzle mouth along a passage longitudinal axis,
• the passage converging continuously towards the nozzle mouth thereof, in a convergence portion, as far as a constriction of the passage, to less than 40% of a cross-sectional area at an inlet of the convergence portion,
• the passage diverging continuously in a divergence portion, proceeding from the constriction of the passage, as far as the mouth of the passage, to over 130% of a cross-sectional area at the constriction of the passage;
• wherein the convergence portion transitions in an edgeless manner into the divergence portion at the constriction;
• wherein, in the entire divergence portion, the wall of the passage is at an angle of inclination relative to the passage longitudinal axis of at most 5°;
• wherein the length of the divergence portion is less than 5 times the diameter of the constriction and more than twice the diameter of the constriction.

A laser cutting nozzle for a laser machining unit, the laser cutting nozzle comprising:

• a passage for a laser beam and a cutting gas,
• the passage extending between a nozzle inlet and a nozzle mouth along a passage longitudinal axis,
• the passage converging continuously towards the nozzle mouth thereof, in a convergence portion, as far as a constriction of the passage, to less than 40% of a cross-sectional area at an inlet of the convergence portion,
• the passage diverging continuously in a divergence portion, proceeding from the constriction of the passage, as far as the mouth of the passage, to over 130% and less than 250% of a cross-sectional area at the constriction of the passage;
• wherein the diameter of the mouth is between 1.8 and 3.5 mm;
• wherein the diameter of the constriction is between 1.3 and 3.0 mm;
• wherein, in the entire divergence portion, the wall of the passage is at an angle of inclination relative to the passage longitudinal axis of at most 5°;
• and
• wherein the length of the divergence portion is less than 5 times the diameter of the constriction and more than twice the diameter of the constriction.