Abstract: An ending target position Xes corresponding to the measurement ending position Xe, a rotation rate pattern Ar to rotate a screw 2, and a hypothetical retraction rate pattern Ab for the screw 2 to retract are set in advance, the remaining rotation rate pattern Ar to stop the screw 2 rotation at the ending target position Xes is predicated by calculation based on the screw position X detected at every specified time interval Ts at the time of measurement, based on which the screw 2 is controlled to rotate to the measurement ending position Xe, the remaining retraction rate pattern Ab to stop the screw 2 retraction at the ending target position Xe based on the screw 2 retraction rate Vd detected at every specified time interval Ts, based on which the screw 2 is controlled to retract to the measurement ending position Xe, the rotation and retraction of the screw 2 are stopped, and subsequently the screw 2 is controlled to reverse rotate by a pre-set constant amount of rotation Rc while position controlling its po

Abstract: An ending target position Xes corresponding to the measurement ending position Xe, a rotation rate pattern Ar to rotate a screw 2, and a hypothetical retraction rate pattern Ab for the screw 2 to retract are set in advance, the remaining rotation rate pattern Ar to stop the screw 2 rotation at the ending target position Xes is predicated by calculation based on the screw position X detected at every specified time interval Ts at the time of measurement, based on which the screw 2 is controlled to rotate to the measurement ending position Xe, the remaining retraction rate pattern Ab to stop the screw 2 retraction at the ending target position Xe based on the screw 2 retraction rate Vd detected at every specified time interval Ts, based on which the screw 2 is controlled to retract to the measurement ending position Xe, the rotation and retraction of the screw 2 are stopped, and subsequently the screw 2 is controlled to reverse rotate by a pre-set constant amount of rotation Rc while position controlling its po

Abstract: An injection mold for molding discs is provided, wherein the injection mold comprises a base die, a board fitted inside the base die, a stamper in the form of a doughnut fitted to the front surface of the board, an outer ring fitted to the front end of the base die, and a sleeve having a flange fitted to the center of the board, the ring and/or the flange fixing the stamper to the board. The injection mold further comprises a thin disc thicker than the stamper interposed closely between the stamper and the board so as that the front surface of the thin disc contacts with the back surface of the stamper. According to the thus constructed injection mold of the present invention, it is possible to prevent dust or dirt from sticking when the stamper is replaced in the field, and to make it unnecessary to replace the mirror surface board, by mounting the combination of the stamper and thin disc on the mold.

Abstract: A novel and improved metal mold for molding a runnerless product can be provided. The metal mold according to the present invention comprises a stationary and a movable mold halves, one of which is provided at the center thereof with a recess and the other of which is provided with a compression core to be retractably received by said recess, said stationary and movable mold halves defining a cavity for the runnerless product, and further comprises a hot nozzle inserted into the recess or the compression core and having a tip projecting therefrom to allow resin to be left around the nozzle. In such a construction, a runner section and a gate are defined by said recess and the compression core so as that they are closable by the movement of said compression core, and thereby the center of the final product, e.g. a disc can certainly be finished without punching, cutting or the like.

Abstract: An improved injection mold for molding an information recording disc is provided.

Abstract: A die assembly for molding a disc such as a compact disc, a video disc or the like by employing an injection molding process. The die assembly comprises a stationary die half including as essential components a stationary platen, a base die half, and an insert die half received on the stationary platen, and a movable die half. The insert die half includes a first insert for fixing the insert die half on the stationary platen, and a first mirror surface board removably received in a cavity of the first insert. The insert die half can be easily installed and removed into/from an installation space defined by a pair of retaining members and a die receiving member and when installed, it can be certainly and easily fixed by a pair of retaining members.

Abstract: A disk substrate molding die is provided in which the quantity of eccentricity of a stamper can be reduced to a small value. The molding die includes a member having mounted thereon a thin plate (19) carrying thereon a recorded transfer signal and an adjusting device consisting of a plurality of pairs of adjusting blocks, each formed of movable blocks (9a) and (9b) and blocks (10a) and (10b) having adjacent surfaces inclined in the moving direction of the movable blocks and common to one another.

Abstract: A method for positioning both dies set to both movable and stationary platens of a plastic molding machine to form a cavity by fitting convex and concave portions formed on the facing surfaces of the dies into a spigot respectively, wherein a movable die is set to the movable platen at the retreat position to secure the movable die to the home position and a stationary die is temporarily clamped at the home position of the stationary platen by pressing the stationary die in the lateral direction by a repulsive member, the movable die is advanced against the stationary die under the above state, die matching of the stationary and movable dies is performed by fitting the convex portion to the concave portion, and thereby positioning of the stationary die is performed by correcting the position of the die before permanently clamping the stationary die to the stationary platen under the state in which the both dies are fastened by the movable platen.

Abstract: A pair of mold bases are provided, each of which possesses a nest-mold insert hole which is open in one direction perpendicular to the mold-closing direction and capable of receiving a plurality of nest molds.The plurality of nest molds, with contacting wall faces between adjacent members, are inserted into the insert hole of each mold base from the open side of the insert hole. In order that the nest molds will not slip in the mold-closing direction, a wall-face engagement is applied between the nest molds and the inner wall of the insert hole and between the nest molds themselves. Mutually corresponding nest molds on both the mold bases, except substitute nest molds, form the cavity for molded products.The nest molds put in the insert hole are fixed by being pushed by a fixing device from the open side of the insert hole.