Abstract: A reciprocating screw for an injection molding machine includes a heating extruder barrel in which the reciprocating screw is mounted rotatably. The barrel has an extruder head and a tail portion. A hopper is coupled with the tail portion of the barrel for feeding plastic granules into the barrel via the hopper. The screw is capable of rotating in the barrel so as to move the plastic granules from the tail portion to the extruder head, thereby melting gradually the plastic granules in the barrel to form a molten plastic material in the extruder head, and extruding the molten plastic material from the extruder head. A check valve is disposed in the extruder head to prevent return flow of the molten plastic material in the extruder head.

Abstract: A lubricating system is installed in a common injection molding machine which includes a stationary mold half unit, a movable mold half unit which can be moved towards and away from the stationary mold half unit, a toggle mechanism coupled with the movable mold half unit so as to be driven to move the movable mold half unit, a mold pressing hydraulic cylinder having a piston rod coupled with the toggle mechanism so as to drive the toggle mechanism, and an oil feed system coupled with the mold pressing hydraulic cylinder so as to provide hydraulic pressure for the mold pressing hydraulic cylinder to drive the toggle mechanism.