Screw tooth core-returning mechanism and die

The invention relates to the technical field of injection moulding, in particular to a screw tooth core-returning mechanism and a die. The screw tooth core-returning mechanism comprises a rack, a gear, a center shaft, a guide shaft, a first insert and a first insert pin, wherein the center shaft is of hollow structure; the gear is coaxially arranged on the center shaft and is meshed with the rack;a thread is formed in one end of a gear shaft; the center shaft is coaxially connected with the guide sleeve; the first insert is arranged in the center shaft; an exhausting passage is arranged on the first insert; the first insert pin is arranged in the first insert; and an exhausting groove is formed in the axial direction of the first insert pin and communicates with the exhausting passage. The die comprises a die box and a plurality of screw tooth core-returning mechanisms; the screw tooth core-returning mechanisms are mounted on the die box. The rack is directly meshed with the gear to reduce driving abrasion of the gear; the center shaft is coaxially connected with the guide sleeve, so that guiding exit of the center shaft is facilitated, and abrasion of the center shaft is reduced;and the exhausting groove communicates with the exhausting passage to exhaust air in the die to facilitate forming of colloid in a cavity.