| 摘要 |
PROBLEM TO BE SOLVED: To reduce a recovery cost by folding a used core small to reduce a volume. SOLUTION: This core comprises a drum 1 and an expansion plate 2. The drum 1 comprises axially elongately divided rectangular elements 3 and hinges 5 each bendably connecting both the adjacent elements 3. The hinge 5 is, for example, a plastic thin bending part integrally formed with the elements 3. All the hinges 5 are formed on the inner side of the drum 1, while V-shaped gaps 6 open to the outside are formed between the elements 3 to prevent interference between the adjacent elements 3 when folding the drum 1. The expansion plate 2 is a circular plate having a hole in the center. By tightly pushing the expansion plate 2 into the drum 1, the drum 1 is kept a cylindrical shape. Protrusions 7 receiving the expansion plate 2 for positioning are integrally formed on the inner faces of the respective elements 3.
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