DIAPHRAGM FOR SPEAKER AND ITS PRODUCTION

摘要

PURPOSE:To reproduce sounds in a wide band from a low sound band to a high sound band, by heating a thermoplastic resin sheet so that this sheet is higher according as going from the center toward the outside circumferential part and forming this sheet into a conical shape by cold press. CONSTITUTION:A paper sheet 1 where a high-density polyethylene synthetic pulp (80wt%) is used as a base material and carbon fibers (20wt%) having 5mm. fiber length are used as a reinforcing material is heated between heating plates 2 and 3; and heating plates 2 and 3 have tubes 6 and 7 for flow of cooling water in center parts of discs 4 and 5, and band heaters 8 and 9 are provided on outside circumferences of discs 4 and 5. The temperature of heating plates 2 and 3 is 170 deg.C in the cone part and is 210 deg.C in the outside circumferential part, and the heating time is 2 seconds. The softened paper sheet is formed into a conical shape between upper and lower dies 10 and 11 by cold press. A formed diaphragm 14 has 90g/m<2> face density in the center part and has 75g/m<2> face density in the outside circumferential part.