Abstract: To reduce the need for manual work, improve productivity and reduce the fabrication cost in the method for molding a lead screw for converting a rotational movement into a linear movement, there are provided a method and a die assembly which may involve the steps of forming a plurality of holes in a wall of a tube in a spiral arrangement, preparing a metallic die assembly provided with a cavity defining a thread groove adapted to form the thread crest matching in position with an array of the holes, placing the tube in the cavity, and injecting synthetic resin material into the cavity so that the synthetic resin material may flow in two separate flows, one flowing inside the core tube, and the other flowing along the outer surface of the core tube. The thread crest is connected to the synthetic resin material filled in the core tube, and can be securely attached to the core tube. Optionally, an annular rotor may be fitted onto the base end portion of the lead screw.

Abstract: To reduce the need for manual work, improve productivity and reduce the fabrication cost in the method for molding a lead screw for converting a rotational movement into a linear movement, there are provided a method and a die assembly which may involve the steps of forming a plurality of holes in a wall of a tube in a spiral arrangement, preparing a metallic die assembly provided with a cavity defining a thread groove adapted to form the thread crest matching in position with an array of the holes, placing the tube in the cavity, and injecting synthetic resin material into the cavity so that the synthetic resin material may flow in two separate flows, one flowing inside the core tube, and the other flowing along the outer surface of the core tube. The thread crest is connected to the synthetic resin material filled in the core tube, and can be securely attached to the core tube. Optionally, an annular rotor may be fitted onto the base end portion of the lead screw.