| 摘要 |
PROBLEM TO BE SOLVED: To provide an inner form device for a vertical shaft structurally simple and easy to operate, permitting efficient and economical construction work when a mortar side wall or concrete side wall is formed in the vertical shaft by use of the device. SOLUTION: A first link 15, a short second link 21 and a long third link 24 are ingeniously assembled to a column 2 erected in a vertical shaft, a sliding element 3 slidably provided around the column 2, and first form pieces 7 and second form pieces 9 arranged alternately to constitute a cylindrical form 6, and the sliding element 3 is displaced downward or upward relative to the column 2 to form the cylindrical form 6 or to reduce the diameter of the cylindrical form 6.
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