Heavy-duty laser plate cutting machine

A heavy-duty laser plate cutting machine comprising in combination:

• a laser source producing a laser beam having an output power of at least 3 kilowatts;
• a cutting head carrying a focusing optic which focuses the laser beam to a focal spot and directs the focal spot toward a workpiece for cutting the workpiece;
• a drive system for controlling relative motion between the cutting head and the workpiece;
• an automatic beam control system interposed between the laser source and the focusing optic for assisting the cutting head to focus the laser beam;
• the cutting head having an adjustment for positioning the focusing optic to position the laser beam focal spot relative to the workpiece during cutting;
• wherein the laser source is stationary, a bridge traversable along a first axis carries the cutting head which is traversable along an orthogonal axis, and the automatic beam control system is operated by the computer numerical control configured to compensate for path length changes as the cutting head and bridge traverse to controllably position the cutting head over the workpiece;
• and
• a slag collection bed underlying the workpiece and capable of absorbing the energy of the laser beam without permanent damages to the machine, the slag collection bed comprising a hard, smooth, metal surface underlying the entire workpiece so as to collect slag as the bridge and cutting head traverse the workpiece during a cut.

A heavy-duty computer controlled plate cutting machine comprising in combination;

• a stationary laser source producing a laser beam having an output power of at least 3 kilowatts;
• a workpiece supporting means;
• a bridge traversable along a first axis carrying a cutting head which is traversable along an orthogonal axis, and a drive system for controlling the relative motion between the cutting head and the workpiece;
• said cutting head having a nozzle, a lens carrier, a focal lens, controllably positioned in an axis normal to the workpiece to position the nozzle with respect to the workpiece, and a drive for adjusting the position of the lens carrier within the cutting head independently altering the position of the laser beam focus spot with respect to the workpiece without adjusting the position of the cutting head in the axis normal to the workpiece;
• an automatic beam control system interposed between the laser source and the focal lens for controlling the diameter of the laser beam on the focal lens;
• the automatic beam control system interposing a first correction for the length of the beam path between the laser resonator output coupler and the focusing optic in the cutting head, and a second correction for thermal lensing of the laser resonator output coupler which integrates the on and off intervals of the laser beam with a thermal time constant of the output coupler;
• a thermal lensing control for the focal lens comprising an integration means integrating the laser source power level output and the on and off intervals of the laser beam with a thermal time constant of the focal lens;
• and
• a slag collection bed underlying the workpiece and capable of absorbing the energy of the laser beam without permanent damage to the machine, said slag collection bed comprising a hard, smooth, metal surface underlaid by a heat resistant insulating and supporting means.