DETECTING METHOD AND APPARATUS OF WELDING SEAM PART OF ELECTRIC-RESISTANCE WELDED STEEL TUBE

摘要

PURPOSE: To correctly detect a welding seam part by detecting the change of the color tone in a circumferential direction of the surface of a tube and specifying a generating part of the temper color at both sides of the welding seam part. ;CONSTITUTION: When an electric resistance welded steel tube 1 is manufactured by an electric resistance welding method, a part where the color is changed as a result of heating, i.e., a part of temper color is generated at both sides of a welding seam part 1A. Generating parts 1B of temper color are symmetric to each other along the seam part 1A, with brownish color. A detecting apparatus 10 of the welding seam part has a chromoscope 11, a spectrum analyzer 12, and an operating/processing device 13. The chromoscope 11 detects the color of the surface of the tube at each part in the circumferential direction. When sampling by the chromoscope 11 is limited, the chromoscope 11 is scanned by a scanning device 14 in the circumferential direction. The analyzer 12 analyzes the wavelength of the color on the surface of the tube based on the detecting result of the chromoscope 11. When the processing device 13 receives the analyzing result of the analyzer 12, the device detects the change of the color tone of the surface of the tube in the circumferential direction, so that the generating parts 1B at both sides of the seam part 1A are specified.;COPYRIGHT: (C)1994,JPO&Japio