PURPOSE: To form cooling water passages with good accuracy without using any pipe materials and to prevent the occurrence of potential difference corrosion, rust, etc. by burying cores and core clampers for forming the cooling water passages.
CONSTITUTION: A product cavity 11 along a spot gun arm is formed, and two pieces of barlike sand cores 12, 13 are set vertically spacially in a transverse direction within this cavity 11. The sand cores 12, 13 will later constitute cooling water flow passages. Clamper members 14, 15... are disposed in circumferentially symmetrical positions in plural positions of the sand cores 12, 13. The respective opposite inside ends of the members 14, 15 are provided in the symmetrical positions on the respective outside circumferences of the cores 12, 13 by adhering or the like, and the respectively symmetrical outside ends are adhered to the right and left inside walls of the cavity 11. A spot gun arm is cast when molten metal M is charged into the cavity 11, wherein the cores 12, 13 try to float up by the pressure of the molten metal, but are prevented from floating by the members 14, 15..., and are thereby held in the correct positions.
NANDATE MASAO
TANAKA SHINOBU
YAMAZAKI HAJIME
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