METHOD AND INSTRUMENT FOR JUDGING GOOD OR BAD CONDITION OF COMPRESSION STROKE FOR CENTER PLUNGER IN SPRUE SEPARATING DIE

摘要

PURPOSE:To control compression stroke and to obtain a tough casting product by measuring stroke of an injection plunger, stroke of a center plunger and stroke from the original point at the time, when the injection plunger retreats, calculating the compression stroke and judging whether this is within the specification or not. CONSTITUTION:After supplying the fixed quantity of molten metal M into the injection sleeve 15, the injection plunger 16 having the cross sectional area A is advanced by the stroke S1, and the molten metal M is pressurized and filled up into cavity K. Successively, a center plunger 22 having the cross sectional area (a) concentrically arranged to the injection plunger 16 is advanced by the stroke S3 - S2 to separate the sprue 14, and the molten metal M is compressed and also the injection plunger 16 is retreated to the stroke S2 position with the molten metal M corresponding to the volume pushed out by advancing the center plunger 22. Successively, the compression stroke epsilon is calculated with the equation from the strokes S1, S2, S3 - S2 and cross sectional areas A and (a). Then, by comparing the calculated compression stroke with the reference compression stroke E, it is judged whether the compression stroke epsilonis good or bad.