Check valve assembly for injection molding apparatus

In a check valve assembly for an injection molding apparatus having a rotatable and axially translatable feed-screw within a barrel bore and adapted for moving a polymeric material through the valve assembly towards an an exit chamber of the apparatus, the check valve assembly characterized by:

• (A) a valve body member attached to the forward end of the feed-screw and moveable with the feed-screw, said body member having at least one valve seat surface thereon;
• (B) an axially slidable valve member mounted on the body member for limited axial movement thereon, said slidable member having;
• (1) at least one valve seat surface which frictionally engages a corresponding valve seat surface on the body member, and
• (2) a circumferential surface at its outside diameter which frictionally engages the inner surface of the barrel bore
• (C) the improvement comprising a plurality of cylindrical recesses extending into at least part of the valve seats, said recesses filled with abrasion resistant disks securely attached therein, said disks effectively reducing frictional wear between relatively co-acting frictional wear surfaces and between the surfaces and the plasticized material as it is moved through the check valve assembly.

In an injection molding apparatus having a rotatable and axially translatable feed-screw within a barrel bore and adapted for moving a polymeric material through the barrel from an input end to an exit end and having a check valve assembly mounted forwardly on the feed-screw toward the exit end to govern the amount of a plasticized polymeric material being ejected from the apparatus, a check valve assembly comprising in combination:

• (A) a valve body having a conically-shaped forward end and a rearward shank end, the forward end having axially oriented flute passages through the valve seat surface and said shank end having a valve passage portion and a threaded end portion for threaded engagement within an axial bore in the end of the feed-screw˜
• (B) a valve seat ring mounted on the shank end of the valve body at the juncture of the valve passage portion and the threaded portion and having a forwardly facing valve seat surface;
• and
• (C) an annular valve check ring mounted coaxially about the valve passage portion of the valve body shank end, said check ring having a forward flat annular valve seat surface and rearward frustoconical valve seat surface for alternate seating engagement with the rearward-facing valve seat surface of the conically shaped forward end of the valve body when the valve is in an opened position and with the forward-facing valve seat surface of the valve seat ring when the valve is in a closed position in response to a back-pressure generated by the plasticized material passing through and forwardly of the check valve assembly;
• (D) the improvement comprising a plurality of cylindrical recesses extending into at least part of the valve seats, said recesses filled with abrasion resistant disks securely attached therein, said disks effectively reducing frictional wear between relatively co-acting frictional wear surfaces and between the surfaces and the plasticized material as it is moved through the check valve assembly.