| 摘要 |
PURPOSE: To enhance the fixing strength and to reduce the thickness by embedding the periphery of a magnetic metal plate at the protruding end face in the central hole of a disk body, inserting the releasing groove for burr and the cylindrical part of a hub provided with a protruding melting rib into a thin flange part, and closely fixing it. CONSTITUTION: The cylindrical part of a resin hub 3 is inserted to the central hole 2 of a disk body 1 made of resin provided with an information signal recording layer, and a thin flange part 5 provided with a releasing groove 5a for a burr is brought into contact with the body 1. The periphery of a magnetic metal plate 6 is embedded on the protruding surface side at the part of the hub 3, a melting rib protruded from the periphery of the groove 5a of the frame 5, and grooves A are provided on both sides of the rib. Accordingly, when the rib 2 is press with pressure to the body 1 to be ultrasonically welded, the burr of the hole A is absorbed to the hole 5a, the molted part of the rib is absorbed to the grooves A, and closely fixed. Thus, the positioning to the body 1 and the fixing strength can be effectively obtained, and the body 1 can be reduced in thickness. |
