| 摘要 |
PURPOSE: A door closure body is provided to eliminate need of impregnation of a door closure body and to prevent oil leakage and durability degradation due to cracks by restraining formation of porosities in the door closure body made of aluminum alloy. CONSTITUTION: An aluminum alloy body material is formed in the shape of a bar, and the bar is cut by a specific length. The body material is extruded to form a chamber(11) of specific appearance and diameter. Thus, a formed body(10B) is obtained. The body is drawn at cold atmosphere. Both opening of the chamber are closed with caps(40) with thread pitches(13) formed at both ends of the body. According to extrusion and drawing, formation of porosities is prevented. Therefore, a door closure body of compact texture is obtained.
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