| 摘要 |
Bowling pins formed by molding a plastic shell about a foamed plastic core have not heretofore come into practical use because of inability to withstand shocks in service, resulting in separation of the shell from the core. According to the present invention, a foamed thermoset (non-melting) copolymer is employed for casting the core. Thereafter, before casting a plastic shell thereabout, the core surface area is substantially increased by simply removing the core surface skin, thereby opening the outermost thermoset core cells for filling by the shell material.
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