| 摘要 |
PURPOSE:To keep the outside diameter constant independently of variance of temperature by arranging circularly arc-shaped members at proper intervals to form a take-up part and connecting individual arc-shaped members on the outside peripheral surface of a core part through ribs. CONSTITUTION:With respect to a hub 10, arc-shaped members 11 and 11 are arranged circularly at proper intervals 12 and 12 to form a take-up part 13, and arc-shaped members 15 and 15 having plural rackets 14 on inside peripheral surfaces are arranged circularly at proper intervals 16 and 16 to form a core part 17, and both end parts of arc-shaped members 11 and 11 and those of arc-shaped members 15 and 15 are connected to each other by ribs 18, and thus, they are formed into one body. Consequently, when temperature rises, ribs 18 are bent in accordance with the expansion of members 11 and 15, and expanded components of members 11 and 15 are escaped to intervals 12 and 16, and an outside diameter D2 of the hub 10 is corrected properly. When temperature falls, contracted components of members 11 and 15 are supplied to intervals 12 and 16, and the outside diameter D2 is corrected properly.
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