Patent EP-2359974-A2 (EP)
Inventor: JAESCHKE BIRGER
IPC: B23K9/09
Filed: 2010-11-19
Abstract: The light-arc welding process comprises burning an electrical arc between a fused welding electrode continuously fed to a welding torch and a workpiece in a protective gas atmosphere, passing a material melted by the welding electrode into a melting bath on the workpiece, supplying a pulsed welding current to the welding electrode by a welding current source (12), where the pulsed welding current has a basic current phase, a pulsed current phase and an intermediate current phase subsequent to the pulsed current phase, and regulating the welding current in the intermediate current phase. The light-arc welding process comprises burning an electrical arc between a fused welding electrode continuously fed to a welding torch and a workpiece in a protective gas atmosphere, passing a material melted by the welding electrode into a melting bath on the workpiece, supplying a pulsed welding current to the welding electrode by a welding current source (12), where the pulsed welding current has a basic current phase, a pulsed current phase and an intermediate current phase subsequent to the pulsed current phase, and regulating the welding current in the intermediate current phase on the basis of a current set-point value. The current set-point value is determined in dependent of the current actual value of the welding current and the voltage actual value of the output voltage of the welding current source. The current set-point value of the intermediate phase is determined under the consideration of the correction factors. The sum of the current actual value of the welding current and the voltage actual value of the output voltage of the welding current source is formed for the determination the current set-point value of the intermediate phase. The current actual value and the voltage actual value are measured with a correction factor. The current set-point value of the intermediate phase is formed from the sum of the current actual value and the deviations of the voltage actual value of the output voltage of the welding current source from a voltage fixed value and of the current actual value of the welding current from a current fixed value, where the deviations are measured with the correction factor. The welding current is cyclically regulated in the intermediate current phase, where an actual value of the welding current measured in the preceding regulating cycle, the set-point value of the welding current determined in the preceding regulating cycle and the actual value of the output voltage of the welding current source measured in the preceding regulating cycle are collected for the determination of the current set-point value in an actual regulating cycle, where the values are measured with the correction factor. A guiding parameter is assigned to several correction factors and the correction factors with the assignment are saved in a memory element. The correction factors associated to the guiding parameter are retrieved during the demand of a determined guiding parameter and are collected for determining the current set-point value of the intermediate current phase. The current set-point value of the intermediate current phase is limited to a minimum value and a maximum value. The duration of the intermediate current phase is limited to a minimum value. The intermediate current phase has duration of 5-10 ms. A representation actual value is detected, which characterizes the progression of the welding current in the intermediate current phase and is compared with a representation set-point value, where the current set-point value of the intermediate current phase, the current set-point of the basic current phase and/or the pulse frequency of the welding current are changed on the basis of the comparison of the representation actual value with the representation set-point value. The representation actual value is compared with maximum and minimum values of the current set-point value of the intermediate current phase, and is changed in dependent of the results of the comparison of the current set-point value of the basic current phase and/or the pulse frequency of the welding current. The current set-point value of the basic current phase and/or the pulse frequency of the welding current are regulated, where a predetermined set-point value of the basic current- and/or pulse frequency regulation or a gain factor of the basic current and/or pulse frequency regulation is changed in dependent of the deviation of the representation actual value from the representation set-point value. The gain factor is proportionally or integral-proportionally changed to the amount of the deviation of the representation actual value from the representation set-point value. The actual value of the welding current smoothed over the duration of the intermediate current phase is used as representation actual value in the intermediate current phase. An independent claim is included for a welding current source for performing a light-arc welding process.