| 摘要 |
PURPOSE: A method for manufacturing a ball for a big ball valve is provided to obtain the miniaturization of grain by a ring rolling process, and to remove foreign materials. CONSTITUTION: A method for manufacturing a ball for a big ball valve comprises following steps. A raw material formed into a plate shape is cut into a rectangular shape(S100). The cut material is pressed and firstly formed into flat cylindrical shape(S210). The material after the first step is bored in an axial direction(S300). The material with a hole is secondly formed into cylindrical forging(S400). The material after the second step is formed into a ball shape using a mold(S600). |
