| 摘要 |
PROBLEM TO BE SOLVED: To provide a film opening forming unit with a mandrel, that can adjust an open/close amount of open/close levers according to a circumferential length of a cylindrical film, and can always maintain the open/close levers parallel to each other when they are opened.SOLUTION: A mandrel 43 includes a base member 44, four open/close levers 45, an open/close mechanism part 46 attached to the base member 44 and for supporting the open/close levers 45 so as to open and close them, a biasing means 47 for biasing the open/close levers 45 in respective closing directions, an opening/closing means 48 for opening and closing the open/close levers 45, and an opening amount adjusting means 49 for adjusting a maximum opening amount of the open/close levers 45 by the opening/closing means 48. The open/close mechanism part 46 has a plurality of parallel link mechanisms arranged radially from the center of the base member 44. The opening amount adjusting means 49 changes the shape of the parallel link mechanisms in an open state to adjust the maximum opening amount of the open/close levers 45. The open/close levers 45 are attached to the parallel link mechanisms so as to be parallel to each other when they are opened. |
