Vaccum die casting method and a die for vaccum die casting

Abstract

A vacuum die casting method may include: coupling a fixed die and a movable die to each other; closing a molten metal pouring hole formed in a sleeve using an injection plunger operated in the sleeve, which is formed on a lower side of the fixed die or the movable die; performing vacuum decompression in a cavity formed between the fixed die and the movable die using a vacuum decompression device connected to chill vent blocks provided on upper portions of the fixed die and the movable die; supplying oxygen in the cavity using an oxygen supply device connected to the chill vent blocks after completing the step of performing vacuum decompression; and supplying a molten metal to the cavity through the molten metal pouring hole.

What is claimed is: 
     
         1 . A vacuum die casting method, comprising:
 coupling a fixed die and a movable die to each other;   closing a molten metal pouring hole, which is formed in a sleeve, using an injection plunger operated in the sleeve, which is formed on a lower side of the fixed die or the movable die;   performing vacuum decompression in a cavity formed between the fixed die and the movable die using a vacuum decompression device connected to chill vent blocks, which are provided on upper portions of the fixed die and the movable die;   supplying oxygen in the cavity using an oxygen supply device connected to the chill vent blocks after completing the performing of the vacuum decompression; and   supplying a molten metal to the cavity through the molten metal pouring hole.   
     
     
         2 . The vacuum die casting method of  claim 1 ,
 wherein the vacuum decompression device is connected to the chill vent blocks through a vacuum decompression line, and   wherein the oxygen supply device is connected to the chill vent blocks through the vacuum decompression line and an oxygen supply line.   
     
     
         3 . The vacuum die casting method of  claim 1 , wherein, in the performing of the vacuum decompression, a vacuum decompression valve, which is provided on the vacuum decompression line, is controlled to be opened following a signal indicating the molten metal pouring hole is closed. 
     
     
         4 . The vacuum die casting method of  claim 3 , wherein the performing of the vacuum decompression is performed until a pressure in the cavity reaches 200 mmHg or less. 
     
     
         5 . The vacuum die casting method of  claim 1 ,
 wherein the supplying of the oxygen in the cavity includes performing a primary oxygen supply until the pressure in the cavity reaches 1200 mbar or more;   the supplying of the molten metal to the cavity is performed after the primary oxygen supply is completed; and   the supplying of the oxygen in the cavity further includes performing a secondary oxygen supply to supply less oxygen than the primary oxygen supply after the supplying of the molten metal to the cavity is started.   
     
     
         6 . The vacuum die casting method of  claim 5 , wherein the molten metal is molten aluminum. 
     
     
         7 . The vacuum die casting method of  claim 5  further comprising:
 proceeding with an injection by operating the injection plunger after the supplying of the molten metal to the cavity; and 
 completing the secondary oxygen supply at a time point when the injection plunger passes the molten metal pouring hole during the injection. 
 
     
     
         8 . A die for a vacuum die casting, the die comprising:
 a fixed die and a movable die;   an injection plunger operated in a sleeve, which is formed on a lower side of the fixed die or the movable die;   a vacuum decompression device connected to chill vent blocks, which are provided on upper portions of the fixed die and the movable die, and configured to perform vacuum decompression in a cavity formed between the fixed die and the movable die; and   an oxygen supply device connected to the chill vent blocks and configured to supply oxygen in the cavity.   
     
     
         9 . The die of  claim 8  further comprising:
 a vacuum decompression line connected from the vacuum decompression device to the chill vent blocks; 
 a vacuum decompression valve provided on the vacuum decompression line; 
 an oxygen supply line connected from the oxygen supply device to the chill vent blocks; and 
 an oxygen supply valve provided on the oxygen supply line. 
 
     
     
         10 . The die of  claim 9 ,
 wherein the vacuum decompression valve is controlled following a signal of a vacuum sensor provided in the cavity; and   wherein the oxygen supply valve is controlled following a signal of an oxygen sensor provided in the cavity.   
     
     
         11 . The die of  claim 8 ,
 wherein the chill vent blocks are formed as a pair in the fixed die and the movable die, respectively, and   wherein the chill vent blocks have a molten metal inlet communicating with an upper end of the cavity and introducing the molten metal when the fixed die and the movable die are coupled to each other, and have a molten metal solidification flow path extending from the molten metal inlet and a gas discharge hole communicating with the vacuum decompression line.   
     
     
         12 . The die of  claim 11 , wherein the molten metal solidification flow path has a gap of 1.0 to 1.2 mm. 
     
     
         13 . The die of  claim 11 , wherein a cross section of the molten metal solidification flow path has triangular uneven structures such that alternating convex portions and concave portions are repeated and bent several times. 
     
     
         14 . The die of  claim 13 , wherein an interior angle of each of the convex portions and the concave portions is 40 degrees or less. 
     
     
         15 . The die of  claim 8 , wherein the chill vent blocks have a conformal cooling channel in which a coolant is allowed to efficiently flow.