| 摘要 |
<p>An improved method is provided to cast a one-piece wheel having a circular hub and a plurality of airfoils. The method includes providing a mold having a circular main section and a plurality of open-ended airfoil forming sections. Each of the airfoil forming sections has a thick leading edge portion and a thin trailing edge portion. During a casting operation, the mold is preheated while it is spaced from a chill. The mold and chill are then moved into abutting engagement with the chill extending across the open outer end portions of the airfoil forming sections. The relatively thick leadingedge portions of the airfoil forming sections are disposed adjacent to a portion of the chill. Molten metal is poured into the mold cavity and flows outwardly through the airfoil forming sections into engagement with the chill. This results in solidification of columnar grains of metal in a direction toward the center of the mold cavity. As the molten metal is solidifying, heat is conducted at a greater rate from the relatively thick leading edge portions of the airfoils than from the relatively thin trailing edge portions of the airfoils. Therefore, the columnar grains grow in a direction parallel to the central axes of the airfoils.</p> |
