| 摘要 |
PURPOSE:To prevent an Al material from being flawed easily, and also to decrease the number of working processes by performing alumite processing to the Al material, and thereafter, drawing its outside peripheral surface by a die. CONSTITUTION:An outside surface 4 of a pipe material 2 made of Al is oxidized electrochemically and an oxide film 3 is formed. This primary product 5 is passed through a cold rolling drawing process. For instance, the tip of the mouthed primary product 5 is drawn by a chuck 8, passed through between a round die 9 and a plug 9 and the area is reduced, and a product of a desired size is obtained. According to this method, the pipe material 2 is scarcely subject to bruise or other flaw by the alumite processing, and handled easily by a die. Also, the cutting process for elevating the roughness of the surface can be omitted.
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