Patent ID: 7704428
Filing Date: 2010-04-27
Classification: B29C,B29K,H04R

Abstract:
1. A method for manufacturing a diaphragm for use in an electroacoustic transducer in a multi-layer structure which includes a first diaphragm layer of synthetic resin molded in a predetermined shape by injection molding and a second diaphragm layer layered in intimate contact on the first diaphragm layer, the method comprising: executing successively a pre-molding step and an injection-molding step, thereby providing the multi-layer structure in which the second diaphragm layer is layered on the first diaphragm layer in such a manner that entire surface of the first diaphragm layer and the second diaphragm layer that are opposed to each other are in intimate contact with each other, wherein the pre-molding step includes: attaching the second diaphragm layer to a mating surface of one of die parts of an injection molding die; and closing thereafter the injection molding die to give a sheet material a certain shape corresponding to the predetermined shape; and the injection molding step includes: injecting synthetic resin material constituting the first diaphragm layer into the injection molding die thus closed thereby to form the first diaphragm layer; and forming a die gap necessary to inject the synthetic resin material constituting the first diaphragm layer, before injection of the synthetic resin material by moving either one die part by a predetermined distance in a direction in which both die parts constituting the injection molding die leave each other, wherein one of the die parts to which the second diaphragm layer is attached includes: a plurality of sheet positioning pins penetrating an outer edge of the sheet material to secure the sheet material during the operation of closing the injection molding die in the pre-molding step; and a sheet pressing-down unit continuously pressing the sheet material positioned by the sheet positioning pins to prevent wrinkles from occurring on the sheet material until the end of the injection molding step.