| 摘要 |
PURPOSE:To measure numbers of points at a time without contacting nor destruction by arranging a radiation source and its detectors at the periphery of a tube material and rotating the tube material and radiation source relatively, and detecting a radiation passed through the tube material in an overlapping state, and then calculating the thickness of the tube. CONSTITUTION:The radiation source 10 is provided closely to the outer peripheral surface of the tube material 14, and plural, e.g. two detectors 12A and 12B are arranged symmetrically across the straight line connecting the center O of the outer peripheral surface of the material 14 and the radiation source 10 so that the angle between the straight lines connecting the radiation source 10 and detectors 12A and 12B is 1/(2N) as large as 360 deg., i.e. alpha/2. Then, the radiation source 10 and detectors 12A and 12B are rotated in one body around the center O to perform detection at every angle alpha, i.e. at N measurement points which divide the outer peripheral surface of the material 14 by N equally. The thickness of the material 14 is calculated while one of the final measurement points and one of the 1st measurement points overlap each other after one turn around the material. |
