Patent ID: 7527493
Filing Date: 2009-05-05
Classification: B29C

Abstract:
1. A precise control non-return valve assembly for an injection molding machine, said molding machine comprised of an elongated helical plasticating screw that rotates about an axis and reciprocates along said axis within a heated barrel, to discharge molten plastic material through said non-return valve at a discharge end of said screw, said non-return valve assembly comprising: a) moving from upstream to downstream, an outwardly extending shaft that is integral with or has a means for attachment to said screw that is preferably diametrical in shape said shaft having a means for attachment for a hardened pin with a conical portion at the distal end that is designed to match the cone of an discharge chamber passageway; b) a rear seating area that is integral with or mates up with the face of said plasticating screw and allows passage of molten plastic material between it and a ring; c) a ring that is a free rotating un-attached shutoff mechanism whose inner and outer periphery is diametrical in shape and fits with minimal clearance between it and said heated barrel, that is sandwiched between said rear seat and a bushing assembly that is positioned downstream of said screw and rear seating area; d) a pin that fits snugly into a machined hole in said shaft that protrudes above the surface of the shaft and is designed to accept a hardened bushing that is slipped over the top of the pin to form a bushing assembly; e) a bushing assembly that is positioned such so as to govern the forward downstream movement of said ring that is sandwiched between it and said rear seating area; f) a bushing assembly that consists of at least two bushings and a hardened pin whereas the bushing that is cylindrical in shape with an inside diameter that fits in close proximity to the outside diameter of said pin but is free to spin about the axis of the pin, said bushing is free to spin about said hardened pin but is governed in movement on the “Y” axis by said shaft and the barrel inside diameter.