Internal expansion pull pin mechanism and molding mechanism

The embodiment of the utility model provides an internal expansion pull pin mechanism and a molding mechanism, and belongs to the field of insert injection molding. The internal expansion pull pin mechanism and the molding mechanism comprise an expansion sleeve, the top end of which is used for penetrating into an insert of the molding mechanism; the expansion inner pin is arranged in the expansion sleeve, and the diameter of the top end of the expansion inner pin is larger than the inner diameter of the expansion sleeve; the top plate is connected with the expansion inner pin; and the push rod is connected with the top plate and is parallel to the length direction of the expansion inner pin. When the mold is closed, the fixed mold pushes the push rod to move downwards, so that the expansion inner pin moves downwards, the expansion sleeve arranged outside the expansion inner pin expands outwards and has the trend of moving downwards, and the insert sleeving the expansion sleeve is tightly attached to the mold