Abstract: Disclosed is a valve gate apparatus for an injection mold comprising: a valve gate 6 in communication with a mold cavity; a valve pin 3 adapted to be actuated to open and close the valve gate 6, received therein for reciprocal movement in the axial direction of a probe assembly 1 equipped with a body heater 2; and a resin melt passage 7 formed within the probe assembly 1 at the position where the valve pin 3 is opened; the resin melt passage 7 having a gradually curved region 8 formed adjacent the opening end of the passage.

Abstract: A method for runnerless injection molding of a synthetic resin, provided with a novel valve gate for performing intermittent temperature control to forcibly change the property of a molten or solidified resin material adjacent to the gate, capable of performing a precision molding operation without leaving an improper gate mark. The apparatus therefor comprises a runner 3 with a temperature maintaining means for storing a molten resin and forming an injection passage, a gate 1 in communication with a cavity 2 connected to the end of the runner 3, a valve pin 4 enclosed within the runner 3, and an intermittent temperature control assembly P.

Abstract: A valve gate injection molding apparatus, in which the gas produced within a heating probe is discharged through a gas discharge outlet groove from the base side of a valve pin, leak of the resin melt is prevented by flowing a cooling fluid for controlling the temperature to increase viscosity of the resin melt, and preventing overheat of the valve pin actuating assembly caused by heat conduction from the heated and pressurized resin melt.