Abstract: A disc-molding mold includes a first support plate disposed at the stationary side of the mold; a first mirror-surface disc attached to the first support plate; a first guide ring disposed radially outside the first mirror-surface disc and attached to the first support plate; a second support plate disposed at the movable side of the mold; a second mirror-surface disc attached to the second support plate; a second guide ring disposed radially outside the second mirror-surface disc and attached to the second support plate; a guide post attached to either the first or second guide ring and projecting toward the other guide ring; and a guide bushing attached to the other guide ring and adapted to guide the guide post. The first and second guide rings each have a temperature control medium passage formed therein in order to allow passage of a temperature control medium. Thus, the thermal expansion of the first guide ring is made equal to that of the second guide ring.

Abstract: A disc-molding mold includes a first support plate disposed at the stationary side of the mold; a first mirror-surface disc attached to the first support plate; a first guide ring disposed radially outside the first mirror-surface disc and attached to the first support plate; a second support plate disposed at the movable side of the mold; a second mirror-surface disc attached to the second support plate; a second guide ring disposed radially outside the second mirror-surface disc and attached to the second support plate; a guide post attached to either the first or second guide ring and projecting toward the other guide ring; and a guide bush attached to the other guide ring and adapted to guide the guide post. The first and second guide rings each have a temperature control medium passage formed therein in order to allow passage of a temperature control medium. Thus, the thermal expansion of the first guide ring is made equal to that of the second guide ring.

Abstract: A horizontal type disk injection mold apparatus having a stationary and a movable mold base, cylindrical cavity molds provided at the center of each base, and a pair of cylindrical guide rings provided concentrically at the outer peripheries of each disk cavity mold, one such guide ring having a female tapered end and the other guide ring having a male tapered end facing and fitting into the female tapered end. One of the guide rings has a plurality of parallel grooves. The other guide ring has a plurality of guide blocks, each such guide block fitting within a parallel groove on the first guide ring. During mold clamping and mold opening, the guide blocks fit into the parallel grooves, ensuring that the disk cavity molds are maintained along the same longitudinal axis during mold opening.

Abstract: A stamper plate attaching/detaching device of an injection mold for forming an optical disc substrate wherein a stamper plate is supported in a cavity which is formed by a cavity side disc cavity plate, a movable disc cavity plate, and a cavity ring. The stamper plate attaching/detaching device is equipped with a section for holding the outer circumferential rim of the stamper plate by means of the inner circumferential rim of the cavity ring, which inner circumferential rim is larger than the outer diameter of the stamper plate. A plurality of pairs of permanent magnets, which have magnetic poles in parallel with respect to a central line are buried, with phase differences, on the same radial line of the cavity side disc cavity plate and the movable disc cavity plate. The cavity ring rotates between a first angle position and a second angle position in relation to the cavity side disc cavity plate and the movable disc cavity plate.

Abstract: A horizontal type disk injection mold apparatus having a stationary and a movable mold base, cylindrical cavity molds provided at the center of each base, and a pair of cylindrical guide rings provided concentrically at the outer peripheries of each disk cavity mold, one such guide ring having a female tapered end and the other guide ring having a male tapered end facing and fitting into the female tapered end. One of the guide rings has a plurality of parallel grooves. The other guide ring has a plurality of guide blocks, each such guide block fitting within a parallel groove on the first guide ring. During mold clamping and mold opening, the guide blocks fit into the parallel grooves, ensuring that the disk cavity molds are maintained along the same longitudinal axis during mold opening.

Abstract: An optical disk metal mold apparatus includes a fixed cavity plate; a movable cavity plate facing the fixed cavity plate; a disk-shaped plate disposed on at least one of the fixed and movable cavity plates such that it is movable with respect thereto; a stamper plate concentrically supported on the at least one of the fixed and movable cavity plates by the disk-shaped plate such that it is movable with respect to the disk-shaped plate and the at least one of the fixed and movable cavity plates; wherein the stamper plate and the disk-shaped plate are each made of a material and further configured such that a difference between respective deformations of the disk-shaped plate and the stamper plate caused by expansion and contraction thereof due to temperature changes during a molding cycle is smaller than a difference between respective deformations of the stamper plate and the at least one of the fixed and movable cavity plates caused by expansion and contraction thereof due to temperature changes during a mol

Abstract: An apparatus for guiding and aligning fixed side and movable side disk cavity plates of disk injection molding dies of an injection molding device is provided with a plurality of first grooves formed on the outer surface of the fixed side disk cavity plate and a plurality of second grooves formed on the outer surface of the movable side disk cavity plate, wherein each of the first grooves and second grooves form a pair of aligned grooves parallel to the center axes of the fixed and movable side disk cavity plates. The apparatus further comprises a plurality of guide blocks fixed to one groove of a pair of aligned grooves and engaged with the other groove of the pair.

Abstract: An injection molding die for simultaneously molding a plurality of optical disc base boards. The die has a stationary die assembly portion that includes a first base plate having a first center axis, and a plurality of first cavities each having a respective center axis. The first cavities are arranged in an equally spaced relationship along a circumference of a circle coaxial with the first center axis. The die also has a movable die assembly portion that includes a second base plate having a second center axis, and a plurality of second cavities each having a respective center axis. Each second cavity positionally corresponds to a respective first cavity. The first center axis is aligned with the second center axis using a guide rod fixedly secured to the first base plate and that extends along the first center axis, and by using a guide member that extends along the second center axis to be positionally coincident with the first center axis.