Abstract: At the operation of a suction pump, a negative pressure is generated in a supply-side pipe line, a cooling passageway of a mold, and a return-side pipe line. Cooling water stored in a water tank is sucked by the negative pressure, flows from a first feed-water inlet to the supply-side pipe line, flows through the supply-side pipe line, and enters the cooling passageway of the mold. After the cooling water cools down the mold while flowing through the cooling passageway of the mold, it flows out to the return-side pipe line. Additionally, at the operation of the suction pump, a negative pressure is also generated in a bypass pipe line. The cooling water stored in the water tank is sucked by the negative pressure, flows from a second feed-water port to the bypass pipe line, and enters the return-side pipe line via the bypass pipe line.

Abstract: A mold cooling device includes an air feeding and discharging circuit 22 which effects the driving by air of a pump section 1 for feeding a cooling liquid to a fluid flaw passageway 65a fanned in a mold 64 and the feeding of air to the fluid flow passageway 65a. Letting (Dx) be the outer diameter-corresponding dimension of the holed convex portion 53x of a cast article 64x, (D1) be the outer diameter of the pin section 65 of the mold 64, (t1) be the outer peripheral thickness of the pin section 65, and (T1) be −5.103+(0.621×Dx)−(1.068×D1)+(3.61×t1), the time (T) for feeding cooling liquid to the fluid flow passageway 65a after completion of the pouring of molten metal into the mold 64 is set so that the relation T1-0.5 seconds ≦T≦T1×0.5 seconds is satisfied.