| 摘要 |
PROBLEM TO BE SOLVED: To provide a method for manufacturing a valve box for butterfly valves which is capable of improving a molding failure.SOLUTION: The method for manufacturing a valve box for butterfly valves comprises a process of using an inner mold 11 having an inner mold body 13 forming a ring portion and a cylindrical projection 14 forming a valve rod support portion, and a lower mold 12 on which the inner mold 11 is mounted to stick a glass fiber sheet base material 21 with a resin to an inner mold body 13 so that it surrounds the base end of a cylindrical projection 14, a process of disposing a preform 22 formed in a ring shape from the stacked glass fiber sheet base materials in the outer circumference of the inner mold body 13, a process of binding the preform 22 to the inner mold 11 by winding a roving 23, and a process of mounting the inner mold 11 on the lower mold 12 and disposing the glass fiber sheet base material 24 in the circumference of the preform 22 bound by the roving 23. |
