Method and apparatus for casting

Abstract

A method and apparatus for casting wherein molten metal is treated to create conditions of whole volume solidification in the mold. The treating of the molten metal can include the application of vibration in specified manner under specific frequency and amplitude for causing multiple sites of crystallization throughout the mold, or the treating can be by use of activators which are formed during casting, either directly from the molten metal stream by dispersion or from a mineral which concurrently with casting is milled, to a finely ground powder, dehydrated and fed into the molten metal throughout the metal to speed solidification and crystallization at multiple sites. Solidification speed can be more than doubled while eliminating pouring defects and improving the cast metal structure. The methods are applicable to various methods of casting including continuous casting and the methods of vibrating and use of activators can be combined with improved results.

Description

RELATED APPLICATIONS[0001]This application claims priority of U.S. provisional application No. 60 / 935,152 filed Jul. 27, 2007 and U.S. provisional application No. 61 / 004,115 filed Apr. 11, 2008. The disclosures of these provisional applications are hereby incorporated by reference.TECHNICAL FIELD[0002]The present invention involves new methods and apparatus directed to improving the quality of both casts and ingots of ferrous and non-ferrous metals involving treating the molten metal to create conditions of whole volume solidification (crystallization) in the mold through the use of either mechanical vibrations, including direct agitation of the liquid steel, or through the use of suspension pouring (activators).BACKGROUND AND SUMMARY[0003]V. A. Povidaylo et al. report in their 1963 article “Casting in Vibration Molds” that the idea of improving the properties of cast steel by vibration in the process of solidication was mentioned for the first time by D. K. Chernov back in 1868. Re...

AI Technical Summary

Benefits of technology

[0004]The use of suspension pouring (activators) to speed solidification of cast metal is known. Made from steel activators presently used industrially in casting are produced in specialized plants, transported to the casting production site and have a tendency to oxidize, interact with the molten steel being cast and thus cause non-metallic inclusions in the steel end product worsening the steel ingot quality, increasing its cost.

[0005]There is a need for improved casting methods and apparatus, directed to improving the quality of both casts and ingots, which avoid the aforementioned drawbacks and particularly which reduce losses, increase productivity, eliminate pouring defects and improve the product quality. The present invention addresses this need. According to the disclosed, preferred embodiment of the invention, the improved method of casting of the invention comprises pouring molten metal into a mold and treating the molten metal to create conditions of whole volume solidification (crystallization) in the mold. The treating includes at least one of:

[0008]adding activators to the molten metal so they are dispersed throughout the mold and act as solidification sites to speed solidification.

[0009]Each of these treatments has been found to create conditions of whole volume solidification (crystallization). The vibrations at the frequencies and amplitudes indicated keep stirring the molten metal thus creating the conditions of whole volume solidification. In addition, the invention includes the combined use of vibration and suspension pouring (activators) in accordance with the invention for better cast and ingot quality.

[0011]According to another embodiment, it has been found that for larger, multi-ton ingots, direct agitation of the molten metal is more advantageous in creating the conditions of whole volume solidification (crystallization). As compared with using a vibroplate method, this method allows the use of lower powered vibrators. In the example embodiment the waveguide can be made of either a refractory ceramic material, a steel rod, or a water cooled agitator.

Problems solved by technology

However, in the known methods of casting with vibration, both casts and ingots, there remains considerable losses with physical and chemical heterogeneity in the cast metal structure.

Made from steel activators presently used industrially in casting are produced in specialized plants, transported to the casting production site and have a tendency to oxidize, interact with the molten steel being cast and thus cause non-metallic inclusions in the steel end product worsening the steel ingot quality, increasing its cost.

Images