| 摘要 |
A reel on which a web, such as magnetic tape, is to wound is formed of molded synthetic resin and comprises a generally cylindrical hollow reel hub, a circular flange at one end of the hub and integrally formed therewith, and a rib portion generally closing off the other end of the reel hub. A circular sub-flange is thermally welded to the rib portion at that end of the reel hub, for instance, by an ultrasonic welding technique. In order to prevent the reel hub, in which the synthetic resin material may have undergone a dimensional change after welding, from causing undulations in an edge of the tape wound on it, the reel hub is provided with a thin cylindrical portion at the same end of the hub as the rib portion. The top of the cylindrical portion is separated from the sub-flange. The thin cylindrical portion can be defined by an annular recess in the end of the hub. In one arrangement, an annular cut-out is provided contiguous with the annular recess and the cut-out receives a mating projection on the sub-flange. |
