Abstract: A stringiness-preventing pad having a resin passage hole defined by partition leaves is interposed between a sprue bush and an injection cylinder nozzle so that the partition leaves are spread by the pressure of molten resin material being injected into a mold and elastically closed upon completion of injection. The resin material solidified in the sprue is prevented from stringing by virtue of the partition leaves when removing a molded object from the mold.

Abstract: A cassette-type molding die comprises a die plate unit having fitting bores and a cassette die unit including movable and stationary cassette plates between which a molding cavity is defined, an ejector cassette plate, and ejector pins disposed between the movable cassette plate and the ejector cassette plate. The cassette die unit can be detachably inserted into the fitting bores of the die plate unit. As a result, the cassette die unit can be easily exchanged with another cassette die unit while the movable and stationary die plates of the die plate unit are very close together. This speeds up the process of changing cassette die units, and also allows for the overall cassette-type molding die to be smaller than conventional units.

Abstract: A rotary block having a gate is rotatably mounted within either one of stationary or movable die plates so that the gate forms a resin passage interconnected to a molding cavity in the stationary die plate in the mold closing state. A gate slug which is inevitably formed on a molded article in injection molding can effectively be cut off by rotating the rotary block so as to intercept the resin passage before a mold opening process.