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US 4,311,185 AGranted
Injection piston for die casting
AssigneeGebrueder Buehler AG
InventorRene Zimmerman
Life of this patent
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AssigneeGebrueder Buehler AG
InventorRene Zimmerman
Estimating the term…
An injection piston for a die casting machine comprising, a piston die having a chamber therein open at one end, a die rod having an end slidable in the chamber for changing the volume thereof. A coolant is supplied to the chamber to act as a damper to the movement of the die rod toward the press die when the injection piston is moved under pressure into a mold. The coolant flows in a coolant path comprising a feed path defined in the die rod and a discharge path at least a portion of which is defined between the press die and the die rod and the rest of which is defined in the die rod. A slidably mounted immersion valve is in the end of the die rod adjacent the chamber and movable into a neutral, a first and a second position for selectively permitting the flow of coolant into and out of the chamber, blocking the flow of coolant altogether and permitting the flow of fluid only out of the chamber depending on the increase of pressure exerted on the injection piston as it is forced into a mold. A restraining member is biased toward the immersion valve for restraining its motion between its first and second operating positions.
An injection piston in a die casting machine comprising, a press die having interior walls defining a chamber therein open at one end, a die rod having an end slidable in said chamber through said open end thereof, said die rod movable to move said press die under pressure into a mold, said die rod defining a coolant feed path into said chamber for the passage of coolant at a working pressure and a coolant discharge path for the passage of coolant out of said chamber, an immersion valve movably mounted in said feed path which is exposed to said working pressure of the coolant on one side and a pressure of coolant in said chamber on another side thereof, said immersion valve being in a neutral position for the passage of coolant through said feed and discharge paths when said chamber pressure in less than said working pressure, and in a first operating position for the blockage of coolant in said feed and discharge paths when said chamber pressure at least equals said working pressure and in a second operating position for the passage of coolant in said discharge path but not in said feed path when said chamber pressure exceeds said working pressure by a selected amount, and restraining means engaged with said immersion valve when it is in said first operating position for restraining said immersion valve from moving to said second operating position until said selected amount is reached.
A die construction for a die casting machine comprising, a press die movable into a mold, a die rod slidably connected to said press die and movable to move said press die under pressure into said mold, hydraulic damping means connected between said press die and said die rod for damping a movement of said die rod toward said press die when said press die is slowed down by a backpressure acting on its pressure surface, and a cooling liquid circuit for providing coolant through said die rod and to said press die, said coolant comprising a hydraulic medium for said hydraulic damping means, said cooling liquid circuit comprises means defining a coolant feed path in said die rod, said press die having internal walls defining a chamber with said die rod slidable in said chamber to change the volume thereof, said feed path communicating with said chamber and including an enlarged diameter portion, an immersion valve slidably mounted in said large diameter portion of said feed path having a channel defined therethrough communicating said feed path with said chamber, said die rod having an end face facing said chamber with an opening therein, said immersion valve slidable in said opening and movable from a neutral position for the flow of coolant through said feed path and into said chamber to a first operating position with said immersion valve channel closed when a coolant pressure in said chamber is at least equal to a working pressure of said coolant in said feed path.
A die construction for a die casting machine comprising, a press die movable into a mold cavity, a die rod slidably connected to said press die and defining with interior walls of said press die a hydraulic fluid chamber, said die rod movable to move said press die under pressure into said mold, hydraulic damping means connected between said press die and said die rod for damping a movement of said die rod towards said press die when said press die is slowed down by a back pressure acting on said press die, said hydraulic damping means comprising means defining a hydraulic fluid supply conduit in said die rod to said chamber and means defining a hydraulic fluid outlet conduit in said die rod from said chamber, said chamber being closed to said mold cavity, said chamber decreasing in volume when said die rod is moved to apply pressure to move said press die, said reduction in volume forcing hydraulic fluid out through said hydraulic fluid outlet conduit to damp the movement of said die rod toward said press die, said hydraulic fluid outlet conduit including a portion defined between said die rod and press die which is varied in cross-sectional area, with the cross-sectional area of said hydraulic fluid outlet conduit reducing with reduced volume of said chamber to increase a resistance to flow of hydraulic fluid in said hydraulic fluid outlet conduit, said hydraulic fluid supply conduit, said hydraulic fluid outlet conduit and said chamber form a cooling liquid circuit for providing coolant through said die rod and to said press die, said coolant comprising a hydraulic medium for said hydraulic damping means.
Dependencies are inferred from the claim text.