| 摘要 |
PROBLEM TO BE SOLVED: To correspond to sharp curvature as well as width by providing a first moving block on a front drum part free to move in the diameter enlarging direction, providing a second moving block at a position corresponding to the first block on a rear drum part free to move in the diameter enlarging direction and furnishing a moving broken-type jack free to slide in the moving direction of the first or second moving block. SOLUTION: A front drum part 3 is constituted of a front central block 3a and left and right blocks 3b, 3c on the left and the right of the front central block 3a free to move in the diameter enlarging direction. Driving mechanisms 7a, 7b, 7c are respectively set on each of front end parts of the front central block 3a and the left and right blocks 3b, 3c. One ends of fixed broken-type jacks 11a, 11b, 11c, 11d, 11e are pin-connected to a female block 4a and the other ends are pin-connected to a rear central block 5a respectively. One ends of moving broken-type jacks 13a, 15a are respectively connected to the left and right blocks 5b, 5c, and the other ends are set on the female block 4a free to slide in the width direction. |
