| 摘要 |
PURPOSE:To allow a resin to certainly reach the end part of a cavity without increasing the injection pressure of a resin to a runner, in an injection mold equipped with a film gate, by gradually increasing the longitudinal cross section of the film gate along the runner as going away from a resin injection passage. CONSTITUTION:A molten resin is injected in a runner 2 from a resin injection passage 3 and injected in a cavity through a film gate 4. The slit width of the opening 41 on the cavity side of the film gate 4 is made less than that of the opening 42 on the side of the cavity of the film gate 4 to increase an injection speed. The opening width of the opening 41 is continuously increased toward both end parts 41b of the opening 41 from the central part 41a thereof and the cross-sectional area of the resin in the film gate 4 along the flow direction of the resin is gradually increased as going away from the resin injection passage 3 to reduce the resistance of the passage. By this constitution, the injection pressure from both end parts rises and the resin extends to the end part of the cavity and no deformation is generated. |
