| 摘要 |
PURPOSE:To improve a molding cycle without causing deterioration in quality, by a method wherein the tip part of a cooling water hole is formed conically close to a part facing on a gate, a rib is stretched out to the cooling water hole on the inside of a core and provided about parallel with a flowing direction of the cooling water in a mold for bottomed cylindrical injection moldings. CONSTITUTION:Cooling water streamed into a cooling water hole through a feed hole 15 is lifted along a partition plate 12, turned round the upper part of the partition plate 12 at the tip part of the same, descended and streamed out into a discharge hole 16. A ceiling face 19 of a folded back part of a cooling water hole 13 is formed into a state of a truncated cone and its upper base 19a is situated directly below a gate 6. A pair of ribs 20, 21 stretched out to the cooling water hole 13 about in parallel with a flowing direction of the cooling water are provided on the ceiling face 19. With this construction, the tip part of a core bushing 9 can be reinforced and thinned. Therefore, heat transfer from the upper base 19a to the tip face becomes easy, molten resin within a cavity 3 in the vicinity of the gate 6 is cooled efficiently and solidification time is shortened. Then a molding cycle can be improved by holding fixed quality without generating poor external appearance. |
