| 摘要 |
A mold assembly and method for molding a substantially hemispherical construct from pre-expanded polystyrene beads. The mold assembly includes a female half mold; a mating male half mold; a first male mold insert mountable on the male half mold and having a continuous, peripheral, beveled edge; and a second male mold insert mountable on the first male mold insert. For forming a construct having an impact-resistant exterior layer and an energy-absorbing interior layer, such as a motorcyclist safety helmet, the beads are initially molded under heat and compression between the female half mold and the first insert to form a first intermediate product of a first volume having a continuous, peripheral, beveled edge; said product is thereafter molded under heat and compression between the female half mold and the second insert to a second, reduced volume to form a compressed, second intermediate product, the beveled edge of the first intermediate product serving to uniformly distribute the force applied thereto. The second intermediate product is then remolded to the same volume to improve volume stability, and thereafter backfilled between the male half mold and the female half mold with additional pre-expanded polystyrene beads to form an energy-absorbing inner layer.
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