| 摘要 |
PURPOSE:To easily and surely detect a weld defect part at a low cost by disposing a light emitting device and photodetector so as to face each other behind a means for welding the butt part of a metallic tape and measuring the presence or absence of the received light. CONSTITUTION:The light emitting device 10 consisting of a diode, etc. and the photodetector 1 consisting of a phototransistor, etc. are disposed to face each other behind the means 4 for welding the metallic tape 2 in the stage of producing a corrugated pipe 8. A light shielding plate 13 is provided to prevent the disturbance of the operation of the light emitting device 10 and the photodetector 11 by the emission of the light from the means 4. The light which is emitted by the element 10 and is passed through the weld defect part such as hole or pinhole is detected by the photodetector 11. The weld defect part generated during welding is surely detected the above-mentioned mechanism without visual inspection.
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