| 摘要 |
PURPOSE:To attain ease of manufacture, by using a spiral ribbon member as a core and sticking a skin member in which radial ribs are continuously provided on the surface of the core member. CONSTITUTION:The ribbon member made of a light metal foil such as aluminum foil or a resin film having a ridigity is wound in spiral to form the core member 4. On the upper and lower surfaces of the core member 4, skin members 5, 6 made of a light metal such as aluminum or a resin film and in which radial ribs 7 are continuously provided on the entire surface are pasted with bonding. |
