| 摘要 |
PROBLEM TO BE SOLVED: To improve flexibility of resin molding using a hot runner.SOLUTION: A valve pin 3 includes a communication recessed portion 21 wherein one section in the axial direction on the outer peripheral surface is recessed in order to communicate a cavity 13 with a flow passage 6 in such a state that the tip end advances to the position where it enters the cavity 13. The advancing/retreating positions of the valve pin 3 which communicates the cavity 13 with the flow passage 6 by the communication recessed portion 21 is the communication position. When the valve pin 3 retreats from the communication position within a range maintaining the state wherein the tip end enters in the cavity 13, the outer peripheral surface at the tip end side rather than the communication recessed portion 21 fits to a gate 14 to seal the gate 14. A controller (not shown in the figure) sets the valve pin to the communication position until the pressure keeping step of molten resin is completed. When the pressure keeping step is completed, the valve pin 3 is retreated to a predetermined molding position within a range of maintaining the state wherein the tip end enters in the cavity 13. |
