Screw for direct molding, injection molding apparatus, and kneading piece

A screw for direct molding that transports, toward a downstream side, thermoplastic resin supplied from an upstream side, while melting the thermoplastic resin, and that kneads molten resin which has been transported thereto, together with an additive material introduced at an intermediate point, the screw for direct molding comprising:

• a screw main body;
• and
• a kneading piece main body detachably attached to an end part of the screw main body on the downstream side, wherein
• the screw main body includes a first stage positioned on the upstream side and a second stage positioned on the downstream side,
• a main flight in a spiral form is provided on an outer circumferential surface of the first stage,
• a plurality of flights in a spiral form are provided on an outer circumferential surface of the second stage,
• a plurality of flights in a spiral form are provided on an outer circumferential surface of the kneading piece main body,
• at least one cutout part is formed at an intermediate point of the flights provided on the kneading piece, and
• a step part into which the molten resin enters is formed at an apex part of the main flight, by cutting out a section of the apex part of the main flight on the downstream side.