To strengthen winding by arranging a sliding piece to slide a constitutional piece to wind or unwind in the neighborhood of a winding drum.

A telescopic structural body sequentially delivers a constitutional piece from a winding drum 11 in accordance with driving of a driving mechanism. The delivered constitutional piece is smoothly guided by a sliding piece 30 set in the neighborhood of the winding drum 11, a superposed stepped part 2d of a rear part form 2 is fitted and inserted into a front part form 2 at a connecting shaft 2j, and when a rise part 2e is fitted in an engagement recessed part 2g of the front and rear forms 2, fitting recessed part 2h of the front and rear forms 2 coincide with each other, a rear part of an engagement plate 3 comes to be in resilient pressure engagement state by resilient pressure work of a spring body. A fitting piece 3b of the engagement plate 3 is pressurized and closely fitted in the fitting recessed parts 2h communicated to each other by coincidence of the front and rear forms 2 by passing through pressure rollers 27, 28 facing each other which are clamping and pressurizing the constitutional piece in this state. Roughly simultaneously with this, a rear form horn type cam 2f prevents looseness by pressurizing a lower part of a presser part 3e of the engagement plate 3 upward, and it is formed into a strong rectilinear columnar shape. Consequently, it endures heavy pressure and impact force at the time of extension.