Cutting a workpiece e.g. stainless steel by laser beam, comprises generating laser beam having Gaussian-type intensity distribution using laser source, and modifying laser beam so as to obtain ring type intensity distribution laser beam

摘要

The process comprises generating a laser beam (10) having a Gaussian-type intensity distribution using a fiber or disc laser source (1), modifying the Gaussian-type intensity distribution laser beam generated by the laser source so as to obtain a ring type intensity distribution laser beam with a hollow center portion, and cutting a workpiece using the ring type intensity distribution laser beam. The Gaussian-type intensity distribution laser beam is modified by passing the laser beam through a conical or sphero-conical single lens (17). The workpiece has a thickness of 4 mm. The process comprises generating a laser beam (10) having a Gaussian-type intensity distribution using a fiber or disc laser source (1), modifying the Gaussian-type intensity distribution laser beam generated by the laser source so as to obtain a ring type intensity distribution laser beam with a hollow center portion, and cutting a workpiece using the ring type intensity distribution laser beam. The Gaussian-type intensity distribution laser beam is modified by passing the laser beam through a conical or sphero-conical single lens (17). The workpiece has a thickness of 4 mm, and terminates in a tip base angle (theta ) for 0.5-10 minutes of arc. The laser beam generated by the laser source is conveyed by a fiber conveyor (2), and passes through a collimating optical unit and a focusing optical unit. The single conical lens is arranged in a downstream of the fiber conveyor, is arranged between the collimating optical unit and the focusing optical unit, and is arranged in a focusing head (3). The laser source has a beam parameter of = 10 mm.milliradians (mrad), and a diameter in a focal length of 100-500 mu m. The conical lens is adapted to produce a laser beam with ring type intensity distribution comprising maximum intensities located on either side of a propagation axis of the beam and separated from each other by a distance of 50-95%. The hollow central portion includes a minimum intensity value, which is 50% less than maximum intensity peaks (less than 10%) located on either side of the propagation axis of the beam. The laser beam has a wavelength of 1.06-1.10 mu m and a capacity of 1-8 kW, and is focused by the focusing lens so as to obtain a focused laser beam in the vicinity of a lower surface and an upper surface of the workpiece.