| 摘要 |
<p>A design for the hubs of magnetic tape cassette spools guarantees a smooth winding surface for the tape without the casting cracks and grooves present in many such spools. The mould has an inlet into which the nylon or plastic material is injected and the position of this is on one of the flat hub surfaces. Opposite this inlet is a roughly circular block (20) which affects the flow of the molten material so that a smooth winding surface without contraction cracks is produced. To balance the hub other similar blocks arranged symmetrically round it to give a total of three inlet apertures (20, 22, 23) in the final spool.</p> |
