The oil pan (oil pan) grey cast iron produced by ZHY casting is a large engine part. Its function is to close the crankcase and cannot be used as the shell of the oil storage tank, prevent impurities from entering, collect and store the lubricating oil flowing back from the friction surfaces of the engine, dissipate heat and prevent the oxidation of lubricating oil. Therefore, its function determines the requirements of high quality of grey cast iron.

The overall dimension of grey cast iron of oil pan is 2300 mm × 1 030 mm × 560 mm, the single weight of gray iron casting is 1200 kg, the main wall thickness is 18 mm, and the bottom of the oil pan belongs to the thin-walled large plane, as shown in the figure. The material trademark of gray iron castings is G3000 (equivalent to national standard HT300), the hardness is required to be above 187hb, magnetic particle flaw detection is required, no cracks, sand holes and other casting defects are allowed, and the dimensional accuracy is required to reach grade ct9 of ISO 8062-3-2007 general dimensions, geometric tolerances and machining allowances of castings.

(1) For large oil pan castings, adopting the process of horizontal casting and vertical casting can theoretically avoid the blowhole casting defects on the large plane at the bottom of the oil pan. However, due to the difficulty of operation, it is not feasible in actual production.

(2) For gray iron castings with a large plane on the upper box, it is necessary to strengthen the exhaust of the sand core, pay attention to the positioning of the sand core, and prevent the sand core from floating or shaking, resulting in gas overflow to the mold cavity.

(3) Pouring temperature has a great influence on the quality of thin-wall large plane gray iron castings.