| 摘要 |
<p>PURPOSE:To make removal of core after casting as well as a hard machining of boring unnecessary by a method wherein the casting is effected centering around a metallic pipe manufactured beforehand upon casting the runner, to form the balance holes by utilizing the hole of the pipe. CONSTITUTION:A balance hole 15 is formed by a method wherein a pipe 21 is made by a kind of metal, same as or different from a runner 20, so as to have a predetermined dimension, thereafter, a necessary number of pipes 21 are inserted as the cores into the predetermined positions in the mold upon casting the runner 20 to cast them integrally with the runner 20 and form the balance holes by the holes of the pipes 21. In such a manufacturing method of the balance holes 15, removing work of the core or machining work for boring becomes unnecessary and the manufacturing thereof may be facilitated.</p> |
