Retracting and expanding device of unreeling machine

The invention provides a collapsing and expanding device of an unreeling machine, which solves the problems of axial deviation and the like of the collapsing and expanding device and comprises a central rotating shaft, a collapsing and expanding base is mounted on the outer side of the central rotating shaft, and a plurality of collapsing and expanding blocks which are symmetrically arranged relative to the center of the collapsing and expanding base are slidably mounted on the collapsing and expanding base through a slope guide mechanism. Arc-shaped contraction and expansion plates are installed on the outward sides of the contraction and expansion blocks respectively, a synchronous driving mechanism is arranged between the contraction and expansion blocks, and axial positioning mechanisms are arranged between the contraction and expansion plates and the contraction and expansion base. The positioning device has the advantages of good positioning effect, convenience in adjustment and the like. 本发明提供了一种放卷机缩涨器