To obtain a speaker edge which is small in an amplitude at the resonance, easy to mold and sure/easy to integrate with a speaker cone body by injecting material composition for a specific speaker edge into a forming mold so as to react, foam and cake in the mold for forming.
The material composition P for the speaker edge including isocyanate and polyol is injected to the lower mold 42 of the forming mold 40 by the nozzle N of a stirring mixer, then clamped and then, made to react, foam and cake in the mold 40 to form. It is preferable to previously arrange the speaker cone body 20 in the mold 40 at the time and adhere-integrate the inner periphery of the speaker edge to the periphery of the speaker cone body 20 by the reaction of the composition P and chemical reaction at the time of foaming and caking. Thus, this speaker edge is lighter than a speaker edge made of rubber, and the mass of a vibration system never becomes heavy and sound pressure frequency characteristics is never degraded.
KANEKO SHINYA
IKEDA KIYOSHI
YAMAZAKI HIROKO
MATSUSHITA ELECTRIC IND CO LTD