| 摘要 |
A core shaft having, at its outer circumference, lugs for gripping winding cores, wherein the winding cores are securely gripped concentrically, a reduction in gripping force due to air leakage during winding is impeded, and decentering and runout of the winding cores is prevented, thereby enabling a smooth winding or unwinding of a sheet material. The core shaft comprises plural sets of lugs (10) arranged circumferentially equally relative to the center of the shaft; an inner core tube (2) for introduction of air disposed in a central part of the shaft; air cylinders (4) having an axially movable inclined wall (4a) disposed between the inner core tube and the lugs, each air cylinder including therein a spring member (15); and slide fittings (9) having an opposite inclined wall disposed in abutting contact with the inclined wall, the slide fittings being fitted with the lugs so that the lugs are, during winding, protruded equally from the outer circumference by the spring force of the spring member and ,upon mounting or removal of the winding cores, retracted by introduction of air. <IMAGE> |
