Casting Method to Prevent Shrinkage Porosity of Ductile Iron Crankshaft

Abstract

The invention is mainly applied in the technical field of casting of nodular cast iron crankshaft castings of marine diesel engines and particularly relates to a casting method preventing a shrinkagedefect of a nodular cast iron crankshaft. The following steps that (firstly), process design of a cast model and design of a mold bottom plate and a sand box are completed; (secondly) a temperature field during box erecting of a casting is calculated, and hot section portions are determined; (thirdly) chilling blocks are designed at the positions of the hot section portions; (fourthly) riser design is performed, specifically, a spherical riser is arranged at the crankshaft free end to be used for feeding of the free end, and the riser is required to be provided with gas outflow holes; (fifthly) crankshaft, chilling block mold and tool manufacturing and installing are completed; (sixthly) a modeling procedure is completed; and (seventhly) casting and box erecting are performed are adopted.According to the method, the hot section positions are determined, the different chilling blocks are adopted on different portions to be matched according to the structure so that generated defects can be reduced, meanwhile, the riser, the chilling blocks and a manner that box erecting and casting are combined are adopted at the same time to solve the shrinkage defect, the effect is obvious, the production quality is improved, and cost is lowered.

Description

technical field

[0001] The invention relates to a casting method for preventing shrinkage defects of ductile iron crankshafts, which is mainly applied in the technical field of casting castings of ductile iron crankshafts for marine diesel engines. Background technique

[0002] Existing nodular iron crankshafts of diesel engines usually adopt resin sand molding process, which is flexible and widely applicable, and can produce all kinds of crankshafts, but the crankshaft main journal and crank crank neck are prone to shrinkage defects.

[0003] At present, the production of ductile iron crankshafts in the foundry industry mainly includes resin sand technology and iron mold sand coating technology. Due to the large investment, iron mold sand coating technology mainly produces small crankshafts, while resin sand technology is widely used in large diesel engine crankshafts. However, the shrinkage and porosity defects produced at the main journal of the crankshaft and the cranksh...

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