초록 ▼

To produce base boards each usable for an information recording medium such as a photoelectromagnetic disc or the like by employing an injection molding process, an injection molding die of the type comprising a die half on the stationary side and a die half on the movable side includes a cylindrica

To produce base boards each usable for an information recording medium such as a photoelectromagnetic disc or the like by employing an injection molding process, an injection molding die of the type comprising a die half on the stationary side and a die half on the movable side includes a cylindrical supporting member on the stationary side, a die assembly on the stationary side arranged in the cylindrical supporting member, a cylindrical supporting member on the movable side, a die assembly on the movable side arranged in the cylindrical supporting member, a cylindrical guide member located between both the cylindrical members, a first driving unit for displacing the die half on the movable side, and a second driving unit for actuating an ejector sleeve. Each injection-molding operation is achieved by way of the steps of filling a cylindrical die cavity with a pressurized molten resin, forming a center hole through a molded product of base board, holding the die cavity in the fully closed state, and then re-compressing the molded produce of base board by actuating the first driving unit. While the step of re-compressing is executed, the molded product of base board is squeezed against the die cavity and the outer peripheral surface of a cut sleeve by a high inner pressure of the molten resin with the result that a final molded product of base board has a high density and exhibits a smooth surface on the center hole formed through the molded product of base board.

대표청구항 ▼

An injection molding die for injection-molding base boards in a cylindrical die cavity, comprising: (A) a movable side, including: (1) a first platen; (2) a first base plate; (3) a first cylindrical supporting member integrally secured to the first base plate; and (4) a first die assembly arranged i

An injection molding die for injection-molding base boards in a cylindrical die cavity, comprising: (A) a movable side, including: (1) a first platen; (2) a first base plate; (3) a first cylindrical supporting member integrally secured to the first base plate; and (4) a first die assembly arranged in the first cylindrical supporting member and being operatively connected to the first base plate, including: (a) a first die half fixedly secured to the first platen; (b) an ejector sleeve; (c) a cut sleeve; (d) an ejector pin, said ejector pin, the ejector sleeve and cut sleeve being positioned within the first die half in a coaxial arrangement; (e) a floating member slidably positioned around the first die half to define an outer peripheral surface of the cylindrical die cavity; and (f) a movable plate; (B) a stationary side, including: (1) a second platen; (2) a second base plate; (3) a second cylindrical supporting member integrally secured to the second base plate; and (4) a second die assembly arranged in the second cylindrical supporting member and fixedly secured to the second base plate, including: (a) a second die half fixedly secured to the second platen, the first and second die halves defining a cylindrical die cavity therebetween; (b) a nozzle bush; and (c) a flange bush for supporting a stamper plate, said nozzle bush and flange bush being positioned within the second die half in a coaxial arrangement; (C) first spring means for biasing the floating member toward the second die half; (D) second spring means for biasing the ejector pin away from the second die half; (E) third spring means for biasing the cut sleeve away from the second die half; (F) cylindrical guide member means located between the first and second cylindrical supporting members for aligning the first die assembly with the second die assembly, said guide member means defining a minimum gap between the first and second die assemblies; (G) first driving means for moving the cut sleeve, the ejector pin, and the movable plate, said movable plate displacing the first die half and ejector sleeve; and (H) second driving means for actuating the ejector sleeve so as to remove a finished molded base board away from the cylindrical die cavity; whereby the cylindrical die cavity is filled with pressurized molten resin fed through the nozzle bush to produce a primarily molded base board, the cut sleeve is actuated by said first driving means to form a center hole through the primarily molded base board, the cylindrical die cavity is held in a fully closed state, and the first driving means is additionally activated to recompress the primarily molded product by a distance corresponding to a quantity of recompression to produce a secondarily molded base board, respectively.