| 摘要 |
PURPOSE:To attempt to mold a molded item having no silver streak by forming a resin reservoir on the apex part of a sprue with a diameter being at least the max. diameter of the sprue and a length being at least two times of the diameter of the sprue. CONSTITUTION:A resin reservoir 8 is provided at the apex part of a sprue 5. The resin reservoir 8 has a diameter R being at least the diameter R1 at the bottom part of the sprue 5 and a length L being at least two times of the diameter R1. When a fixed side mold 1, a movable side mold 2 and a slide core 3 are closed to form a cavity 4, a molten resin is injected from a nozzle of an injection molding machine and the first part of the molten resin is entered in the resin reservoir through a sprue 5. A resin cooled while it is passed through the sprue 5 and turned to a cold slug and a successive part of the molten resin are stored in a large resin reservoir 8. Then, the molten resin is fed in the cavity 4 through the sprue 5, a runner 6 and a gate 7. Therefore, not only the cold slug but a resin contg. air and volatile substances are stored in the resin reservoir 8 and a molded item with no silver streak can be obtd.
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