| 摘要 |
A method of producing plastic-based casings including preformed metal fragments for ordnance articles, such as hand grenades, weapon-launched grenades or the like, by rotational molding in a shell-mold; a pulverulent thermoplastic polymer material, such as polyethylene, and steel fragments or particles are introduced into the cold shell mold, optionally in the form of a pre-compact; the closed mold is rotated slowly, i.e. at a speed where the polymer and metal constituents tend to tumble about the inner mold surface and are not held substantially thereon by centrifugal effects; while continuously rotating the shell mold about two or more axes of rotation, the mold is heated by an externally applied hot fluid such as hot gas. As the temperature of the wall of the mold increases, an adhering layer of viscous polymer is formed thereon while the metal fragments continue to tumble; only when most of the polymer material is in a viscous molten state and has formed a layer covering the inner surface of the mold, the metal particles will adhere to the viscous material layer and form a metal particle monolayer thereon; then, the mold is cooled while still in rotation until the polymer solidifies. Finally, the molded product is discharged from the shell and provides an integral casing substantially consisting of an outer wall of polymer material and a monolayer of metal fragments adhering thereto. Molecular cross-linking of the polymer may be effected by a cross-linking agent and activating the latter after formation of the monolayer.
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