| 摘要 |
PURPOSE:To avoid lowering of sensitivity due to vapor deposition of metal and to improve the work efficiency of a titled device, by providing a metal adhesion preventing mechanism in front of the light receiving plane for X-ray detection to prevent the adhesion of metal vapor. CONSTITUTION:When detecting a weld line generating X-ray 9 by irradiating electron beam on an object to be welded, a metal adhesion preventing device 50 is provided in front of a light receiving plane 22 that receives X-ray 9. This mechanism 50 consists of a discoidal shield plate 41, a metal deposition preventing plate 42, and a shutter plate 43. By opening the shutter plate 43, X-ray 9 passes through the shield plate 41 and light receiving plane 22. When the shutter plate 43 is closed, the metal vapor from welded object adheres to the shutter plate 43 and metal deposition preventing plate 42, and does not adhere to the shield plate 41 and light receiving plane 22. When the metal vapor adheres to the shield plate 41 by opening the shutter plate 43 for a long time, the shield plate 41 is rotated, and a new clean face is faced toward the light receiving plane 22. |
