PURPOSE: To absorb shock wave while holding pleasant sound of metal by filling a hollow cylindrical body with foam aluminum body and to reduce crack and break damage by improving pressure resisting strength in a metal bat composed of a hollow cylindrical body.
CONSTITUTION: This metal bat 1 composed of an aluminum alloy comprises a head part 2, a large-diameter batting part 3, a tapered part 4, and a small- diameter grip part 5 and its inside is made into a hollow cylindrical body 6. A honeycomb foam aluminum body 7 is filled in the batting part 3 in the hollow cylindrical body 6. As for a means for manufacturing the foam aluminum body 7, for example, particles of hydroxide and natural mineral, etc., which generate gas at approximately 700°C in the adjacent to its fusing point, are added and mixed with a molten aluminum whose viscosity is improved by such a method as, for example, formation of alloy, oxidation of molten metal, and dispersion of ceramic particles, as foaming agent and formed into a foam aluminum body for retaining the generated gas in the molten metal as independent bubble.
FUJII HIROYASU
ONISHI TOSHIO
HOSOKAWA TOSHIHIRO
