Method for eliminating carbon defects by adopting high-performance coating, negative-pressure firing, vacant shell pouring and quick airflow cooling in lost foam casting

Abstract

The invention discloses a method for eliminating carbon defects by adopting a high-performance coating, negative-pressure firing, vacant shell pouring and quick airflow cooling in lost foam casting. The process comprises the following steps: placing a mould into a sand box; filling dry sand into the sand box; sealing the upper surface of a sand layer with a plastic thin film; starting a vacuum pump, igniting and gasifying the foam mould from a pouring gate under a negative pressure condition so as to form an intact vacant shell cavity, wherein over 95 percent of carbon is discharged out of the molding sand box; pouring molten iron and steel; lifting or cutting the sealing thin film on the top surface of the sand box when the molten iron and steel is in a temperature area where a liquid phase and a solid phase coexist, and then sucking cold airflow into the sand box so as to quickly cool a cast piece; and after stopping the pouring, continuing extracting air for 3 to 6 minutes, and then stopping the vacuum pump. The method can realize the elimination of the carbon defects of the cast piece, grain refinement, and easy falling-off of the coating by discharging and reducing carbon and pouring the vacant shell in the lost foam casting, makes the cast piece have bright and clean surface to comprehensively improve the quality of the cast piece, saves energy and reduce consumption, is high in efficiency and benefit and is applied to industrialized mass production.

Description

Technical field: [0001] The invention relates to lost foam casting, in particular to a method for eliminating carbon defects of castings by adopting high-performance coating negative pressure combustion hollow shell pouring air flow velocity cooling. Background technique: [0002] Lost foam casting (international abbreviation LFC) is a new casting technology representing the 21st century. It has a history of 50 years in the world, and it has been industrialized in China for almost 20 years. About 2,000 lost foam casting factories have been built nationwide, and It is developing at a rapid rate, but the technology is not yet mature. Even in the United States, the original invention of international lost foam casting, the problem of serious carbon defects in lost foam castings is still in the research period. Their goal is to strive for 2013 Years are maturing. The main manifestations of carbon defects are serious carburization, carbon slag pores, carbon ash wrinkling, coarse...

AI Technical Summary

Problems solved by technology

This method not only has cumbersome procedures, high cost, low efficiency, and poor operational reliability—the shell is easy to break and crack, and the molten steel is easy to lift the box or burst the shell during pouring, and it is only suitable for small cast steel with special requirements for carbon addition. The production of parts cannot be applied in large-scale industrial production, and it is even more difficult to promote in China

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