| 摘要 |
PROBLEM TO BE SOLVED: To obtain a lightweight, high-rigidity septic tank by a method wherein a tank structure that forms the shell of the septic tank is made of a fiber- reinforced foamed polyurethane resin and specially-shaped ribs are arranged on the shell. SOLUTION: This tank structure includes a tank upper part 1 and a tank lower part 2 and they are made of a fiber-reinforced polyurethane resin and bonded together with their openings facing each other. Sidewalls 1a and 2a of the tank upper and lower parts 1 and 2 are provided with reinforcing ribs 4 that stretch along the depth and protruded inside the tank. The height H of the protruding ribs 4 is 6-60mm and the curvature radiuses R of carved parts of the ribs 4 are at least 2mm and less than the height H. The tank structure is produced by a forming method wherein the working environment is improved with less scatter of glass fibers at the site and without emission of volatile substances harmful to human body when the tank structure is formed. |
