| 摘要 |
The present invention relates to a structure having a variable diameter, which comprises: a bolt extending along the longitudinal direction thereof; a body arranged on one side of the bolt so as to surround the bolt; a core arranged along the longitudinal direction of the bolt; a plurality of extensions radially arranged outside the core; and a plurality of outer shells surrounding the extensions so as to correspond to the extensions, wherein the extensions are extended to the outside or contracted in the direction of the center by the core according to the rotation direction of the bolt, thereby changing the diameter of the outer peripheral surface. |
