| 摘要 |
In a method for spot welding workpieces, more particularly made of copper, copper alloys, gold or jewellery materials, using laser pulses (31) having a wavelength of 500 to 540 nm to produce welding depths greater than 0.5 mm, preferably 0.8 to 1.3 mm, especially preferably greater than 1.3 mm, wherein the laser pulses (31) have a main pulse section (6b) lasting between approx. 1 ms and approx. 20 ms with a peak pulse power level between approx. 1600 W and approx. 6000 W, the power level of each of the laser pulses (31) has a time plot comprising a temporally first pulse section (6a) in the form of a rising pulse edge, representing the creation of a melting temperature and then a vaporisation temperature in the workpiece; comprising the main pulse section (6b) as a temporally second pulse section, representing the creation of a melt bath with a keyhole in the workpiece; comprising a temporally third pulse section (6c) in the form of a pulse edge which initially falls vertically to at least 3/4 of the power level at the end of the main pulse section (6b) and then falls more gradually, representing the reformation of the keyhole; and comprising a temporally fourth pulse section (3d) in the form of a low pulse plateau, the height of which is between 1/3 and 1/4 of the power level at the end of the main pulse section (6b), representing the cooling of the melt. |
