an apparatus for attaching a plastic wrapping sheet to a composite product formed of a plastic core tube having a web - shaped material wrapped therearound , the plastic wrapping sheet surrounding the composite product so that an end portion extends beyond an end of the composite product , the apparatus including twin closing yokes which are movable towards one another to gather the end portion together , a cylindrical welding head for welding the gathered end portion to the end of the core tube , and a rotatable cutting bead for removing free excess plastic wrapping sheet from within the core tube .