| 摘要 |
PURPOSE:To eliminate the sink of polyolefin plate-shape foam due to a two- stage foaming method. CONSTITUTION:A preforming process is provided before a primary process producing intermediate foam. A preforming mold 10 is equipped with an upper mold (not shown in a drawing) and a lower mold 10a both of which are symmetric up and down. The bottom wall part 12 is constituted of a central circular area part 12a and the digged part 12b provided to the periphery thereof. The depth Xmax of the deepest parts A, B of the digged part l2b is set so as to become larger than the reference depth xo of the circular area part by 5-20%. The internal space shape of the preforming mold has a plate-shape almost similar to the shape of the internal space of the primary mold. The dimension of the internal space of the preforming mold in londitudinal and lateral directions thereof is 90-95% of the dimension of the internal space of the primary mold and the volume of the internal volume thereof is 90-95% of that of the internal space of the primary mold. |
