Abstract: A gas venting arrangement in a high speed injection molding apparatus such as a high speed die casting machine. The gas venting arrangement includes a gas vent control valve which is closable at an optimum timing and at high speed. This valve closure is achievable by providing an improved combination of a control circuit and a valve driving mechanism. The control circuit is connected to a molten metal sensor and sends a high voltage output drive signal to the valve driving mechanism when the sensor detects a first molten metal or a metal splash. The valve driving mechanism includes an electromagnetic valve connected to a pneumatic source and a pneumatically operated valve connected between the electromagnetic valve and the gas vent control valve. The pneumatically operated valve is also connected to the pneumatic source. The electromagnetic valve performs prompt change-over operation upon receiving the drive signal, and supplies driving pneumatic pressure to the pneumatically operated valve.

Abstract: Disclosed is a gas venting arrangement in an injection molding apparatus, and a method for venting gas out of the injection molding apparatus. The gas venting arrangement includes mold halves formed with a gas vent passage in fluid communication with a mold cavity and positioned downstream thereof, a gas vent control valve disposed at a downstream end portion of the vent passage, a detection member disposed at the vent passage for detecting injected material exceeding over the mold cavity, a valve driving mechanism connected to the gas vent control valve, and an electric control means connected between the detection member and the valve driving mechanism. The detection member generates a detection signal upon contact with the injected material and the valve driving mechanism is operated in response to the detection signal through the electric control means to operate the vent control valve.

Abstract: A deflator for injection molding in a cavity. Two exhaust passages connect the cavity to a detection valve and an exhaust valve, which is being pumped. The exhaust passages are arranged so that the molten metal reaches the detection valve before the exhaust valve. Closing of the detection valve triggers the pneumatic closing of the exhaust valve. Also included in the invention is a bounce reduction means for the exhaust valve and a rockable connection for approaching the deflator to the mold.