MONITORING METHOD FOR PLASMA ARC WELDING AND PLASMA ARC WELDING DEVICE

摘要

The method of monitoring keyhole welding with a plasma arc includes the step of measuring output voltages when welding is performed with a constant current, and the step of finding peak frequencies and distributions of welding voltages by analyzing frequencies of the welding voltages which correlate to a molten weld pool (P) vibration among the output voltages measured. The method also includes the step of identifying the peak frequencies that correlate to the molten weld pool (P) vibration, and the step of comparing the identified peak frequencies with a frequency range and determining whether the welding is good or bad. Thus, whether or not good keyhole welding is carried out can be determined with excellent precision by simply comparing the peak frequency that correlates to the molten weld pool (P) vibration with the frequency range.

主权项

1. A method of monitoring welding that continuously welds a welding target area of a welding workpiece when forming a keyhole in the welding target area of the welding workpiece by a plasma arc, the method comprising:
an output voltage measuring step that measures an output voltage when a constant current is used for the welding; a welding voltage frequency analyzing step that analyzes frequencies of those welding voltages, among the output voltages measured by the output voltage measuring step, which possibly correlate to a vibration of a weld pool formed on a back face of a base metal during the welding, to obtain peak frequencies of the welding voltages and their distributions; a peak frequency identifying step that identifies those peak frequencies which possibly correlate to the vibration of the weld pool, based on frequency analysis results of the welding voltage frequency analyzing step; and a determination step that compares the peak frequencies identified by the peak frequency identifying step with a preset frequency range to determine a quality of the welding.