| 摘要 |
PURPOSE:To increase an internal loss, and to increase flexural rigidity, by using a thermoplastic resin foamed body as a core material of a diaphragm part, providing a surface material made of thermosetting resin on both surfaces, and constituting a three-layered structure consisting of the films, thereby making its edge part filmy. CONSTITUTION:On both center surfaces of a foamed body sheet 1 a thermoplastic resin foamed body having prescribed size, thermosetting resin is applied so that it has a prescribed diameter and also the positions of the center parts of both the surfaces coincide with each other on the front and rear sides. This sheet 1 is heated by an infrared heater, etc., and a resin layer 2 is formed on both front and rear surfaces. Subsequently, when the resin layer 2 is hardened, press-molding is executed to form a film, and a conical diaphragm part 3 of a conical shape, and a wave edge part 4 of the out circumference of said diaphragm part 3 are formed as one body. In this way, said diaphragm part 3 is constituted of a three-layered structure consisting of the film to increase flexural rigidity, and also by forming the filmy edge part 4 as one body, an internal loss is increased. |
