| 摘要 |
PROBLEM TO BE SOLVED: To always hold a detection head at the center position of a pipe by providing a guide part capable of being extended and contracted in the radius direction of the pipe and capable of coming into contact with the inner surface of the pipe under pressure to an image detection part. SOLUTION: The stretchable guide 5 provided in the periphery of a holder main body 4 consists of first and second links 6, 7, a wheel 8, a tensile coil spring 10 or the like and the links 6, 7 extend in the axial direction of a steel pipe. The link 6 is attached to the detection head 1 of the main body 4 at its base end part through a pin 12 and made shakable in the radius direction of the steel pipe. A spring 10 connects the base parts of the links 6, 7 mutually and energizes the leading ends of them toward the inner surface of the steel pipe. The links 6, 7 are contracted to insert the head 1 into the steel pipe from the gap of the end part thereof and, when the head 1 and the guide part 5 are positioned along the inner surface of the steel pipe, the links 6, 7 are automatically expanded by the action of the spring 10 and the wheel 8 rolls so as to follow the inner surface of the steel pipe and the head 1 during movement is always positioned at the center of the steel pipe. Therefore, the CCD camera of the head 1 can always photograph the entire inner surface of the steel pipe. |
