| 摘要 |
PROBLEM TO BE SOLVED: To be applicable as a core for eliminating a step height trace even if a thickness of sheets is different, to be easily and inexpensively manufacturable, and to require no labor even in the case of disposal.SOLUTION: This cylindrical and flexible core 1 is wound with the sheets 3. A through-groove 2 penetrating through the inside-outside of a cylinder is formed along the axial direction, and a groove width h of the through-groove 2 is set to the thickness or more of the sheets 3. An end surface on the winding direction side of the through-groove 2 is inclined as a tapered surface t, and when molding the through-groove 2, the through-groove 2 is molded by cutting off a part by an ultrasonic cutter from an existing cylindrical core. |
