Pouring gate structure for nut casting

Abstract

The invention discloses a pouring gate structure for nut casting. The pouring gate structure for nut casting comprises cavities, ingates, a runner and a sprue. During casting, molten metal enters from the sprue, flows into the runner in a distributed manner, and then is injected into the cavities via the ingates, a position where each cavity is connected with the corresponding ingate is an inner gate, a position where the runner is connected with each ingate is a runner gate, the cross-sectional area of each runner gate is greater than that of the inner gate, the cooling speed of the ingates is slowed, replenishment time is sufficient when liquid in the cavity of a casting is cooled by the molten metal, defects of shrinkage holes and shrinkage porosity are eliminated, chilling block treatment and arrangement are not required, a large amount of costs for tools are saved, pore defects which are possibly caused by chilling blocks are eliminated, and the yield of the casting can reach 100%.

Description

technical field [0001] The invention relates to the field of nut casting, in particular to a runner structure applied to nut casting. Background technique [0002] In the production of various iron castings without risers, the probability of shrinkage porosity and shrinkage cavity defects is high, and the rejection rate of castings with compactness requirements is high. Ductile iron nuts are required to have no casting defects in their threads, and have extremely high requirements on the mechanical properties and compactness of castings. The material is QT500-7A. In actual production, shrinkage porosity and shrinkage cavity defects appear at the flange transition figure 1 , the effect of multiple improvement processes is not obvious. The molten metal enters the cavity from the ingate, the wall thickness of the casting is relatively large, the cooling speed is slow, and there is no liquid metal replenishment in the later stage of cooling, which is the main factor that eventu...

AI Technical Summary

Problems solved by technology

Ductile iron nuts are required to have no casting defects in their threads, and have extremely high requirements on the mechanical properties and compactness of castings. The material is QT500-7A. In actual production, shrinkage porosity and shrinkage defects appear at the flange transition. figure 1 , the effect of many times of improving the process is not obvious

The molten metal enters the cavity from the ingate, the wall thickness of the casting is relatively large, the cooling speed is slow, and there is no liquid metal replenishment in the later stage of cooling, which is the main factor that eventually causes shrinkage porosity and shrinkage cavities in the product. To solve this problem, most of the current It is solved by speeding up the cooling speed of castings, that is, figure 2 As shown in Fig. 1, chill iron is installed on the side of the cavity to make the cooling rate of the cavity and the runner roughly consistent. Although the product quality has been improved, it still cannot meet the process requirements, especially for thick-walled workpieces, the effect is not obvious , and the cooling is too fast at the joint between the cold iron and the cavity, which is very easy to produce structural defects of pores

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