A Method for Eliminating Black Spot Defects of Ductile Iron Cutterhead Castings

Abstract

The invention relates to a method for removing defects of a nodular cast iron cutter casting with a thick section, and particularly relates to a method for removing black spot defects of the nodular cast iron cutter casting. According to the method, the furnace charge comprises 40-45% of steel scrap, 5-10% of iron, and 50-55% of pig iron. The method comprises the following steps: machining two dead heads in the upper surface of the cutter pouring position before pouring; dividing a feeding area between the dead heads by using straight cold iron; pouring, wherein a direct nodularizing process is adopted in a pouring inoculation; and carrying out instantaneous inoculation by adopting 0.1-0.2% by weight of silicon nucleating agent in a pouring basin. The method disclosed by the invention is unique; the black spot defects of the products are overcome by controlling chemical components, improving the inoculation process and the inoculation materials and simultaneously adjusting the pouring temperature under the condition that a limited number of cold iron is used; the condition that the exposed surface after finish machining is consistent in color and luster is ensured; a metallographic check tissue is good.

Description

technical field [0001] The invention relates to a method for eliminating defects of thick-section ductile iron cutterhead castings, in particular to a method for eliminating black spot defects of ductile iron cutterhead castings. Background technique [0002] Ductile iron cutter head casting is an important part of cutting tool clamping in high-end machining centers. All surfaces need to be finished, and the surface roughness is required to be high. In the use of machine tools, it is an unpainted and fully exposed appearance surface, and is an important part that affects the quality of machine tools. Although it is light in weight, its wall thickness is 150-300mm. It belongs to thick-walled nodular cast iron. Due to the slow cooling rate in casting production, it is prone to various defects such as spheroidization, gestation decline, graphite floating, and poor spheroidization. Black spot is a common defect of this type of casting. The difference in surface color can be see...

AI Technical Summary

Problems solved by technology

To solve this problem, the method of setting cold iron on the upper and lower surfaces of the cutterhead is usually adopted, that is, through forced cooling, the cooling rate is accelerated, and the spheroidization and gestation decline are eliminated. The disadvantage of this method is that it can only solve the surface problem, and the core part The problem of poor spheroidization still exists, and the operation is complicated

In addition, the use of cold iron will lead to poor surface texture and increase the risk of cold iron choking and inclusion

[0003] So far, there is no way to overcome the above drawbacks