Replaceable air cylinder unit and valve gate for injection molding

Abstract

A mold assembly is provided for use in an injection molding machine and includes a cavity plate defining a cavity adapted to receive a moldable material, and a manifold positioned behind the cavity plate. The manifold includes a passageway for guiding the flow of the moldable material to the cavity plate. A support plate is positioned adjacent the manifold and includes a rear face into which a cup shaped recess extends, a front face opposite the rear face, and a bore extending between the front face and the recess. A nozzle is provided between the passageway in the manifold and the cavity in the plate for directing the flow of material into the cavity, and a valve gate pin extends into the nozzle. The valve gate pin is movable between a forward flow-blocking position and a rearward flow-permitting position, and a cylinder unit moves the valve gate pin between these positions. The actuator includes a drop-in pneumatic actuator secured within the recess of the support plate. The actuator includes a body presenting a front closed end and a rear open end, a movable piston extending through the closed end of the cylinder and being connected to the piston. A cap closes off the open end of the cylinder, and threaded fasteners are provided for holding the cap and cylinder together as a unit. Threaded fasteners are also provided for securing the actuator within the recess of the support plate so that the actuator can be dropped into the recess and secured in place or pulled from the recess as an assembled unit.