Seam position detection method, manufacturing method of welded steel pipe, quality control method of welded steel pipe, seam position detection apparatus, and manufacturing equipment of welded steel pipe

A seam position detection method of detecting a position of a seam portion of a welded steel pipe when the welded steel pipe is heated, the seam position detection method comprising:

• a position detection step of detecting a position of the seam portion after heating and a position of a heating portion from images obtained by capturing the seam portion after heating and the heating portion each irradiated with light having a wavelength different from a wavelength of thermal radiation by heating, the images being captured in a same field of view;
• a determination step of determining whether the position of the seam portion after heating needs to be corrected by comparing
• a position of the seam portion before heating, the position being acquired in advance, and
• the position of the seam portion after heating;
• and
• a correction step of correcting, based on the position of the seam portion before heating, the position of the seam portion after heating when the position of the seam portion after heating needs to be corrected.

A seam position detection apparatus configured to detect a position of a seam portion of a welded steel pipe when the welded steel pipe is heated, the seam position detection apparatus comprising:

• a position detection unit configured to detect a position of the seam portion after heating and a position of a heating portion from images obtained by capturing the seam portion after heating and the heating portion each irradiated with light having a wavelength different from a wavelength of thermal radiation by heating, the images being captured in a same field of view;
• a determination unit configured to determine whether the position of the seam portion after heating needs to be corrected by comparing
• a position of the seam portion before heating, the position being acquired in advance, and
• the position of the seam portion after heating;
• and
• a correction unit configured to correct, based on the position of the seam portion before heating, the position of the seam portion after heating when the position of the seam portion after heating needs to be corrected.