PURPOSE: To omit the welding of a flange and to manufacture the above exhaust manifold at a low cost by pouring molten metal in a mold while heating end parts of a cast steel pipe inserted in the mold from inside and casting the flange as cast-in at outside of the end part of pipe.
CONSTITUTION: The cast steel pipe 5 is cast under condition of the straight pipe and also after forming plural small circular recessed parts 5a at the time of casting this, this is bent to the prescribed shape. Successively, the end part at engine side of bent cast steel pipe 5 is set in through hole 2c in the casting mold 2, and the part at out of the mold in the cast steel pipe 5 is supported with a pipe receiving jig 4, and also the upper and lower molds 2a, 2b are mated. Successively, ignited gas burner 3 is inserted into the through hole 2c to heat the end part of cast steel pipe 5. After that, molten cast steel is poured into the cavity 2d from a sprue under condition of igniting the gas burner 3, and after pouring the molten steel, the gas burner 3 is extingushed and the cast molten steel is cooled. Then, the flange is fitted to the end part at the engine side of cast steel pipe 5 and cast as cast-in. Further, a collective flange 6 is cast to the other end part of cast steel pipe at the same time.
TAGO HIROSHI
SHINODA HOZUMI
SHOJI TAKENORI
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