| 摘要 |
PURPOSE: To prevent movement and damage of an internal casing by molding the internal casing and contracting the same before injecting an elastomeric resin into the gap between external and internal casings. CONSTITUTION: An external casing is heated by rotary molding oeration to form a continuous internal casing 10 made of polyvinylidene fluoride having uniform thickness within a metal casing. After cooling, the internal casing 10 made of polyvinylidene fluoride receives shrinkage large than that of the external casing to form a continuous space 11 between these casings. A slight vacuum is generated through a connection part 4 without closing the connection part 4 and openings 8, 9 and an elastomeric polyurethane resin is injected into the space 11 arranged between the internal and external casings 10, 1 through the opening 8. The obtained drum is suitable for packing a product having activity and desired to hold purity and has excellent collision strength. |
