| 摘要 |
PURPOSE:To facilitate filling of melted resin into a surrounding base part of a needle pin, and to obtain moldings having larger distribution of hollows by a method wherein a rib is formed round the base part of the needle pin with a specified distance kept from the base part so that aeration can be made therethrough. CONSTITUTION:A needle pin 24, provided with a plurality of ejection ports 25 on its upper end, is installed to a gas hole 23a of a core 20 for a cavity 21. A rib 27 is formed to the installation base of the needle pin 24. The rib 27 is made up in the shape of a ring, opening toward the upside and surrounding the pin with a space (t) kept at a specified distance from the base part of the needle pin 24, and a slit 28 is provided to one side of the rib 27. As melted resin flowing into the cavity 21 is flowed into the space (t) through the slit 28 and the opening looking toward the upside, no vacant space is produced between the needle pin 24 and the rib 27. |
