Gas venting device for molding operations
AssigneeToshiba Kikai Kabushiki Kaisha
InventorsMamoru Ozeki, Akihico Tsuda
Life of this patent
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Abstract
A gas venting device for molding operations is disclosed having a valve for closing off a gas evacuation system from a mold when the mold cavity is filled with melt. A positive drive mechanism is provided for closing the valve, and a mechanism is provided for allowing the valve body to close more rapidly by action of the melt itself against the valve body in the event the melt advances more rapidly through the gas vent passages than expected.
Claims18
A gas venting arrangement for use with molding apparatus including a mold having a cavity to be filled with a melt, means for injecting melt into the mold cavity and a gas vent passage communicating with the mold cavity for evacuating gas from the mold cavity ahead of advancing melt as it fills the mold cavity, said gas venting arrangement comprising:
- a housing having a valve chamber with an inlet adapted to be placed in fluid communication with the gas vent passage, and an exhaust port for evacuating gas from said valve chamber;
- an annular valve seat adjacent said inlet;
- a valve body coaxial with said valve chamber and said valve seat and having a valve stem extending rearwardly through said valve chamber away from the mold, said valve body being axially movable forwardly, toward the mold, to open said inlet, and movable rearwardly, away from the mold, to close said inlet in cooperation with said valve seat;
- and
- valve actuation means associated with said housing and including a positively driven, reciprocable drive member and coupling means interconnecting said drive member and said valve stem for transmitting rearward movement of said drive member to said valve stem to positively close said inlet when the mold is full of melt, and permitting said valve body to be driven rearwardly more rapidly by the melt itself to close said inlet if melt advancing through the gas vent passage overtakes the positively driven valve body.
A gas venting arrangement for use with molding apparatus including a mold having a cavity to be filled with a melt, means for injecting melt into the mold cavity and a gas vent passage communicating with the mold cavity for evacuating gas from the mold cavity ahead of advancing melt as it fills the mold cavity, said gas venting arrangement comprising:
- a housing having a valve chamber with an inlet adapted to be placed in fluid communication with the gas vent passage, and an exhaust port for evacuating gas from said valve chamber;
- a cylindrical valve seat adjacent said inlet;
- a cylindrical valve body coaxial with said valve chamber and said valve seat and having a valve stem extending rearwardly through said valve chamber away from the mold, said valve body being axially movable forwardly, toward the mold, to open said inlet, and movable rearwardly, away from the mold, to retract fully within said valve seat and thereby close said inlet;
- a double-acting fluid cylinder and piston assembly at the rear of said housing having a drive rod coaxial with and extending forwardly toward said valve stem;
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- coupling means in said housing, intermediate said valve chamber and said cylinder and piston assembly, interconnecting said drive rod and said valve stem for transmitting rearward movement of said drive rod to said valve stem to positively close said inlet when the mold is full of melt, while permitting faster melt-driven rearward movement of said valve body if the inlet is not closed when melt reaches said valve body, and for transmitting forward movement of said drive rod to said valve stem to forcibly open said inlet before melt is injected into the mold cavity,
- said coupling means comprising a forwardly facing shoulder on the distal end of said valve stem, a rearwardly facing shoulder on the distal end of said drive rod, and a sliding joint embracing the distal ends of said valve stem and said drive rod and having front and rear mutually facing shoulders which mate respectively with said forwardly and rearwardly facing shoulders on said valve stem and said drive rod, the gap between said front and rear shoulders of said sliding joint being greater than the minimum spacing between the shoulders on the distal ends of said valve stem and said drive rod.
A gas venting arrangement for use with molding apparatus including a mold having a cavity to be filled with a melt, means including an injection ram for injecting melt into the mold cavity and a gas vent passage communicating with the mold cavity for evacuating gas from the mold cavity ahead of advancing melt as it fills the mold cavity, said gas venting arrangement comprising:
- a housing having a valve chamber with an inlet adapted to be placed in fluid communication with the gas vent passage, and an exhaust port for evacuating gas from said valve chamber;
- a cylindrical valve seat adjacent said inlet;
- a cylindrical valve body coaxial with said valve chamber and said valve seat and having a stem extending rearwardly through said valve chamber away from the mold, said valve body being axially movable forwardly, toward the mold, to open said inlet, and movable rearwardly, away from the mold, to retract fully within said valve seat and thereby close said inlet;
- means for detecting a predetermined position of the injection ram at which the mold cavity is substantially filled with melt, and for producing a signal when the injection ram reaches said predetermined position;
- a double-acting fluid cylinder and piston assembly at the rear of said housing having a drive rod coaxial with and extending forwardly toward said valve stem;
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- coupling means in said housing, intermediate said valve chamber and said cylinder and piston assembly, interconnecting said drive rod and said valve stem, for transmitting rearward movement of said drive rod to said valve stem, in response to said signal produced by said detecting means, to positively close said inlet when the mold is full of melt, and before the advancing melt reaches and contacts said valve body, and for transmitting forward movement of said drive rod to said valve stem to forcibly open said inlet before melt is injected into the mold cavity,
- said coupling means comprising a forwardly facing shoulder on the distal end of said valve stem, a rearwardly facing shoulder on the distal end of said drive rod, and a sliding joint embracing the distal ends of said valve stem and said drive rod and having front and rear mutually facing shoulders which mate respectively with said forwardly and rearwardly facing shoulders on said valve stem and said drive rod, the gap between said front and rear shoulders of said sliding joint being greater than the minimum spacing between the shoulders on the distal ends of said valve stem and said drive rod.
Dependencies are inferred from the claim text.