| 摘要 |
PURPOSE:To cut off an unnecessary part such as a sprue part without generating a cutting layer, by a method wherein an information disk base and fitting hub are molded at the same time in the same mold, the fitting hub is fitted into an inner diametral part of the information disk base with a moving mechanism of the inside of the mold and a gate part is separated from the information disk base by synchronizing with this fitting action. CONSTITUTION:An assembled body is put into a mold, a projected part 31(a) of a magnetic material fitting tool 31 is inserted into the central part hole 21(a) of a piston 21 for fitting, the mold is clamped and molten resin 35 is injected into the mold through a sprue bushing 13. The molten resin 35 flows into an information disk base forming part 32 a part of the molten resin flows into a reinforcing part forming part 29 and fitting hub forming part 28 also. At a point of time when the molten resin becomes a semimolten state, the piston 21 is moved forward. This advancement generates shearing force of the resin between a gate part 36' and information disk base 32' and separation between the gate part 36' and information disk base 32' is performed. When the advancement of the piston 21 progresses further, a fitting hub 28' is fitted more deeply into a reinforcing part 29' and cutting of the gate part is furthered. |
