| 摘要 |
PURPOSE:To prevent an over-flow of an inner air from an opening part in an under part of the cylindrical substrate by providing on a closed part of a cylindrical substrate, at least one of openings through an inner part of cylindrical substrate. CONSTITUTION:An ascend of a fluid surface in the substrate depends on an amount of an air exhausting from the opening 2, namely on an area of the opening and an inner diameter of the cylindrical substrate. As the more the area of opening against the inner diameter of said substrate becomes large, the more the ascending rate of the fluid surface becomes fast, the relative opening area is necessary to be within the prescribed range. If the opening area is too small, said effect is not obtained. If the interrelationship between the opening area S and the inner diameter of the substrate satisfies 3X10<3=piD<2>/4S<=1X10<8>, preferably 6X10<3=piD<2>/4S<=1X10<7>. An excess adhesion of a coating solution on the inner surface of the cylindrical substrate is prevented whereby a stable coating is performed. The substrate 1 is optionally selected, but preferably is composed of Al. One of the forming method of the substrate is performed by impact-working, restriction-working and drawing- working, and then the formed cylindrical tube is closed with another metal. |
