Aluminum die cast product and method for manufacturing same

Abstract

An object is to provide an aluminum die cast product, e.g., a pressure vessel that requires high airtightness, in which pressure leak or gas leak ratio can be reduced and the product yield can be increased and also to provide a method for manufacturing the product. An aluminum die cast product in which a cast hole is formed by a core pin in a thick portion that is made thicker than other portions, wherein a chill layer with a secondary dendrite arm spacing of at least 5.5 μm or less is provided at the surface of the cast hole.

1 . An aluminum die cast product in which a cast hole is formed by a core pin in a thick portion that is made thicker than other portions, wherein
 a chill layer with a secondary dendrite arm spacing of at least 5.5 μm or less is provided at the surface of the cast hole.   
   
   
       2 . The aluminum die cast product according to  claim 1 , wherein
 a thickness of the chill layer with a secondary dendrite arm spacing of at least 5.5 μm or less is made larger than a cutting allowance of the cast hole that is set in advance.   
   
   
       3 . The aluminum die cast product according to  claim 2 , wherein
 the chill layer with a secondary dendrite arm spacing of at least 5.5 μm or less remains after cutting performed with the cutting allowance.   
   
   
       4 . The aluminum die cast product according to  claim 1 , wherein
 a thickness of the chill layer with a secondary dendrite arm spacing of at least 5.5 μm or less is at least 0.5 mm or more.   
   
   
       5 . The aluminum die cast product according to  claim 1 , wherein
 the aluminum die cast product is a pressure vessel.   
   
   
       6 . The aluminum die cast product according to  claim 5 , wherein
 the pressure vessel is a compressor housing.   
   
   
       7 . A method for manufacturing an aluminum die cast product in which a cast hole is formed by a core pin in a thick portion that is made thicker than other portions, wherein
 a chill layer with a secondary dendrite arm spacing of at least 5.5 μm or less is formed to a thickness equal to, or larger than a predetermined thickness at a surface of the cast hole by passing a flow of a cooling medium through the core pin and locally cooling the cast hole.   
   
   
       8 . The method for manufacturing an aluminum die cast product according to  claim 7 , wherein
 a core pin with a double-pipe structure in which a central pipe is inserted into a hollow core pin body is used as the core pin, the cooling medium is supplied from the central pipe to a distal end portion of the core pin, the cooling medium is forced to flow into a cooling medium channel between the central pipe and the pin body, and the cast hole is locally cooled.   
   
   
       9 . The method for manufacturing an aluminum die cast product according to  claim 8 , wherein
 the cooling medium is caused to flow at a flow rate of 12 cc/s or more.   
   
   
       10 . The method for manufacturing an aluminum die cast product according to  claim 7 , wherein
 a core pin of a partition plate structure in which a partition plate arranged along a pin axial direction is inserted into a hollow core pin body is used as the core pin, the cooling medium is supplied from one of cooling medium channels partitioned by the partition plate, the cooling medium is caused to flow into the other cooling medium channel, and the cast hole is locally cooled.   
   
   
       11 . The method for manufacturing an aluminum die cast product according to  claim 7 , wherein the flow of the cooling medium is initiated simultaneously with, or immediately prior to the completion of melt injection.