| 摘要 |
PURPOSE:To obtain a blow molding having small marks showing existence of concealed ribs at the time of viewing from the outside of the molding, in a manufacture of blow moldings with concealed ribs. CONSTITUTION:A slide board 23 is projectingly installed on only one mold 21 of two opposite molds 21, 22. The two molds 21, 22 define a blow molding cavity in conformity with their inside shapes. The slide board 23 is to be a part of the inside shape of the mold 21 in its tip end, and made to project in the vicinity of the other mold 22. When the molds 21, 22 are closed, parisons held between the tip end of the slide board 23 and the inside surface of the mold 22 are pressed and then fused to each other. Subsequently, at almost the same time that air is blown into the parisons, the slide board 23 is retracted, and secured at the walling position, namely, the position that stretches to the tip end mold 21 cavity surface. In this way, no slide marks are formed at the metal mold 22 side of the blow molding. |
