| 摘要 |
PROBLEM TO BE SOLVED: To provide a monitoring device which determines whether welding quality is good or not at real time in DC butt welding used in the production of a rim for an automobile wheel, and to provide a method therefor.SOLUTION: In the method for monitoring the welding quality of a welded product 17 welded by upsetting butt welding, welding current is made to flow to the butted face of both the edge parts 13a, 13b in a steel sheet 12 via fixed electrodes 15a, 15b and moving electrodes 16a, 16b, and resistance welding is performed. The waveform of welding voltage in a period from the start of energization to both the edge parts 13a, 13b to the completion of the energization is measured by a voltage waveform measurement means 18, and, the voltage waveform measured by the voltage waveform measurement means 18 and the beforehand set standard range of the voltage waveform in the above period are compared by a welding quality discrimination means 19, by which whether the welding in the weld zone 17a of the welded product 17 is good or not is determined. |
