| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To provide a weld crack detecting method capable of easily and reliably detecting a weld crack generated in a weld bead. <P>SOLUTION: When performing the laser beam welding of overlapped portions of flange parts 1a, 2a of thin steel plates 1, 2 by a welding torch 4, a welding range is extensively subjected to the image pickup by an infrared ray image pickup apparatus 11, the picked-up images are transmitted to an image data processor 12 to obtain the temperature change at edge side parts of the flanges 1a, 2a for each measurement point set at a predetermined pitch in the welding direction F. When a crack is generated in the weld bead 3, the cooling at the measurement point corresponding to the cracked part is delayed more than the cooling at the measurement point corresponding to non-cracked parts. Thus, by storing a temperature change curve when any crack is generated in advance in an acceptance/rejection determination device 13, the presence of any weld crack can be easily and correctly determined from the difference in the temperature change. <P>COPYRIGHT: (C)2009,JPO&INPIT</p> |
