Casting apparatus whose cooling flow passage is formed by welding and method for manufacturing the same

Abstract

A casting apparatus for manufacturing a cast product from molten metal includes a molten metal and a cooling portion. The molten metal contacts a surface for contact with the molten metal. The cooling portion forms a cooling flow passage. The cooling flow passage is configured to cool the molten metal contacting surface. At least a part of an inner surface of the cooling flow passage is constituted of a welding portion formed by welding, the welding portion sealing the cooling flow passage. The welding portion is constituted such that an exposure to the molten metal becomes equal to or less than a predetermined ratio with respect to an area of the welding portion constituting the inner surface of the cooling flow passage.

What is claimed is: 
     
         1 . A casting apparatus for manufacturing a cast product from molten metal, the casting apparatus comprising:
 a molten metal contacting surface for contact with the molten metal; and   a cooling portion forming a cooling flow passage, the cooling flow passage being configured to cool the molten metal contacting surface, wherein   at least a part of an inner surface of the cooling flow passage is constituted of a welding portion formed by welding, the welding portion sealing the cooling flow passage, and   the welding portion is constituted such that an exposure to the molten metal becomes equal to or less than a predetermined ratio with respect to an area of the welding portion constituting the inner surface of the cooling flow passage.   
     
     
         2 . The casting apparatus according to  claim 1 , wherein
 the casting apparatus has a plurality of components including a welding component having the welding portion, and   with the plurality of components assembled, the welding portion is constituted not to be exposed to the molten metal.   
     
     
         3 . The casting apparatus according to  claim 2 , wherein
 the casting apparatus is a mold,   the molten metal contacting surface constitutes a part of the mold as a product shape forming surface, the product shape forming surface forming a shape of the cast product set in advance, and   an outer surface of the welding portion is constituted so as not to be exposed to the molten metal by contact with any of outer surfaces of the plurality of components.   
     
     
         4 . The casting apparatus according to  claim 1 , wherein
 the cooling portion is manufactured by welding a material before quenching and subsequently quenching the material.   
     
     
         5 . The casting apparatus according to  claim 1 , wherein
 the casting apparatus is a mold,   the cooling flow passage includes a columnar flow passage, one end of the columnar flow passage being sealed by the welding portion, another end of the columnar flow passage communicating with a circulation path, the circulation path causing a cooling medium to circulate, and   the welding portion has a diameter 1.5 times to 2.5 times of a diameter of the columnar flow passage viewed from an axial direction of the columnar flow passage such that the diameter becomes equal to or less than the predetermined ratio.   
     
     
         6 . The casting apparatus according to  claim 5 , wherein
 the columnar flow passage is a mold whose length from the one end to the other end is longer than the diameter of the columnar flow passage.   
     
     
         7 . The casting apparatus according to  claim 1 , wherein
 the casting apparatus is a sprue bushing, and   the molten metal contacting surface constitutes a path to cause the molten metal to pass through to supply the molten metal to a mold.   
     
     
         8 . A method for manufacturing a casting apparatus for manufacturing a cast product from molten metal, the method comprising:
 providing a molten metal contacting surface for contact with the molten metal and a material before quenching, a part of a cooling flow passage being formed at the material, the cooling flow passage being configured to cool the molten metal contacting surface, wherein   welding at least a part of an inner surface of the cooling flow passage to form a welding portion configured to seal the cooling flow passage, and   the welding portion is constituted such that an exposure to the molten metal becomes equal to or less than a predetermined ratio with respect to an area of the welding portion constituting the inner surface of the cooling flow passage.   
     
     
         9 . The casting apparatus according to  claim 2 , wherein
 the cooling portion is manufactured by welding a material before quenching and subsequently quenching the material.   
     
     
         10 . The casting apparatus according to  claim 3 , wherein
 the cooling portion is manufactured by welding a material before quenching and subsequently quenching the material.