High accuracy injector for die casting machines affording automatic melt level compensation

In a mold charge injector for delivering of a measured charge of molten material into a mold chamber by controlled movement of a displacement plunger into a melting pot containing the molten material, the improvement for keeping molten material in the melting pot at a precisely determined datum level as successive charges are delivered from the pot, comprising in combination, a displacement plunger operational in the melting pot to displace molten material for a plurality of measured charges during supply of a successive series of charges from the pot by movement thereinto and to produce changes of the level of molten materials in the pot as it moves thereinto, first charge delivery movement means for inserting the displacement plunger a controlled distance into the melting pot to measure out a charge of material and inject it into the mold chamber, and second automatic vernier datum level control supplemental movement means comprising a screw adjustment mechanism for adjustably relatively changing the displacement position of said plunger into the molten material in said melting pot and an automatic control circuit making adjustments thereto in increments over a plurality of injection strokes of said first movement means as successive charges are removed from the melting pot to displace the level of the molten material just enough to provide a substantially constant starting datum level of molten materials for the plunger to begin a following injection stroke in response to the first movement means.