초록 ▼

A self-regulating gate valve assembly, adapted for use in a plastic product injection molding apparatus having a mold cavity and a core therein for molding a hollow product of predetermined design, is characterized by a construction substantially eliminating core deflection during plastic molding co

A self-regulating gate valve assembly, adapted for use in a plastic product injection molding apparatus having a mold cavity and a core therein for molding a hollow product of predetermined design, is characterized by a construction substantially eliminating core deflection during plastic molding compound flow in the injection molding apparatus and thus uneven wall thicknesses and weld lines in the hollow molded plastic product. The gate valve assembly includes a valve pin of unique construction for creating a sheath-like flow configuration of the plastic molding compound as it is injected into the mold cavity to produce balanced forces on the mold core to prevent deflection and for closing the gate in a self-regulating manner when the mold cavity is filled.

대표청구항 ▼

A self-regulating gate valve assembly, adapted for use in a plastic product injection molding apparatus having a mold cavity and a mold core therein for molding a hollow product of predetermined design, said gate valve assembly having construction substantially eliminating mold core deflection durin

A self-regulating gate valve assembly, adapted for use in a plastic product injection molding apparatus having a mold cavity and a mold core therein for molding a hollow product of predetermined design, said gate valve assembly having construction substantially eliminating mold core deflection during plastic molding compound flow in the injection molding apparatus and thus uneven wall thicknesses and weld lines in the molded plastic product, said gate valve assembly comprising: a valve housing having passageways therein for receiving plastic molding compound under pressure from a source and including a generally cylindrical gate of restricted dimensions adapted to communicate with the mold cavity for injecting a jet of the plastic molding compound under a predetermined pressure into the mold cavity to impinge upon an end of the mold core and flow around the mold core therein to fill the cavity; a generally cylindrical valve pin having a cross-sectional diameter approximately as great as the dimensions of said gate, an end and a reduced diameter section adjacent said end, said valve pin being movably positioned within said valve housing for movement of said end into seating position with said gate for closing said gate and shutting-off the flow of the plastic molding compound through said gate into the mold cavity and out of seating position with said gate toward the mold cavity with said reduced diameter section positioned within said gate for allowing the low of the plastic molding compound though said gate into the mold cavity, said reduced diameter section of said valve pin comprises a longitudinally-extending cut-out section around the circumference thereof having a reduced cross-sectional diameter at the center thereof and progressively increasing in cross-sectional diameter from the center thereof in both longitudinal directions to form a generally concave outside surface around said valve pin resulting in a uniform balanced flow around said valve pin by the plastic molding compound flowing therearound and into the mold cavity; and means connected to said valve pin for being actuated to move said valve pin longitudinally toward the mold cavity to open said gate and hold said pin in the position of said gate under predetermined forces; whereby, said reduced diameter section and said end of said valve pin cooperate when said valve pin is in the open position of said gate so that the plastic molding compound will flow through said gate and around said reduced diameter section and said end of said valve pin and into the mold cavity and around the mold core in a sheath-like flow configuration to produce balanced forces on the mold core to prevent deflection, and, wherein, the predetermined pressure of the plastic molding compound will produce forces on the end of said valve pin after filling the mold cavity greater than the predetermined forces holding said valve pin open to cause said valve pin to move longitudinally and close said gate in a self-regulating manner.