Deep large nodular cast iron die casting and molding method

Abstract

The invention relates to a casting forming method used for a thick and large nodular cast irondie, comprising the steps as follows: a. die tolerance: the height of the die top is not needed to be increased for supplement contraction; b. a necking typed contraction supplementing gate is arranged on the top of the die and hot spot normally according to nodular cast iron, thus being used for metal liquid contraction supplementing; the gate contraction supplementing quantity is more than 5%; c. the pouring is stable for filling by a bottom pouring type; air in the die sufficiently escapes out and alloy air suction is reduced; d. on the working surface and the hot joint, graphite chilling material with the thickness less than 50% of the wall thickness of the casting is used for cold iron; e. casting sandbox with rigidity is selected and moldng sand is used; f. alloy carbon equivalent is adjusted to the critical value; g. molten steel is spheroidized and gestated by a nodulizer which contains heavy rare earth element; h. by adopting a quick casting type with low-temperature pouring, the large die is taken out at the temperature of 1200-1350 DEG C. The method is applicable to sand casting production and has ideal practical effect.

Description

technical field [0001] The invention relates to casting of ductile iron molds, in particular to a casting molding method of thick and large ductile iron molds. Background technique [0002] Ductile iron molds have high requirements on materials, not only have high requirements on basic properties such as strength, elongation, metallurgy, etc., but also must carry out strict ultrasonic testing on the whole mold, and make strict regulations on casting defects , In addition, there are special requirements for its working surface such as hardness. [0003] When casting ductile iron molds, considering the amount of mold required, foundry manufacturers usually use sand casting methods. In order to meet the high requirements of the material, the common method is to add a certain amount of alloy during the batching, increase the height of the mold blank by 30% to 50% as a feeding riser, and use the high pressure head to ensure the molding of the lower mold blank quality. However,...

AI Technical Summary

Problems solved by technology

[0005] The task of the present invention is to provide a thick and large ductile iron mold casting molding method, which solves the problems of large waste, low process yield and poor quality caused by the commonly used sand casting method at present.