Scrap melter and impeller therefore

Abstract

A device for submerging scrap metal includes: (a) a drive source, (b) a drive shaft having a first end and a second end, the first end being connected to the drive source, and (d) an impeller connected to the second end of the drive shaft, the impeller preferably having two or more outwardly-extending blades. Preferably, each of the blades has a portion that directs molten metal at least partially downward. The impeller design leads to lower operating speeds, lower vibration, longer component life and less maintenance. Additionally, the impeller preferably has a connective portion. The connective portion is used to connect the impeller to the shaft and preferably comprises a nonthreaded, tapered bore extending through the impeller.

Description

RELATED APPLICATIONS[0001]This application is a continuation of and claims priority to U.S. application Ser. No. 10 / 827,941 filed Apr. 19, 2004, which is a divisional application of and claims priority to U.S. patent application Ser. No. 09 / 649,190, filed Aug. 28, 2000, now U.S. Pat. No. 6,723,276.FIELD OF THE INVENTION[0002]The present invention relates to a device, called a scrap melter, for submerging scrap metal in a molten metal bath. The device preferably includes a drive source, an impeller and a drive shaft. The device preferably draws molten metal downward in order to submerge scrap placed on the surface of the bath.BACKGROUND OF THE INVENTION[0003]Scrap melter systems, such as the one shown schematically in FIGS. 1 and 2, generally use two devices, a circulation pump and a scrap melter. As shown in FIG. 1 the vessel V containing molten metal bath B is preferably divided into two compartments. Compartment 1 (called a pump well) houses circulation pump 2. Compartment 3 (call...

AI Technical Summary

Benefits of technology

[0007]The preferred embodiment of the present invention is a scrap melter utilizing an open impeller to reduce jamming or clogging. Thus, the invention can function efficiently in virtually any scrap melting environment, handling particles of virtually any size that are likely to be encountered in any such environment. An impeller according to the invention functions by displacing molten metal to create a downward draw. It provides the benefit of reducing the problems associated with faster operating speeds (i.e., the possible creation of a vortex and turbulence, and / or part failure, greater downtime and higher maintenance costs). The way in which it achieves these results is by (a) displacing more molten metal while operating at the same speed as conventional impellers, and / or (b) moving at least some of the molten metal in a downward or partially downward direction.

[0009]In one preferred embodiment the impeller is preferably a four-bladed cross wherein each blade preferably includes an angled surface that directs molten metal at least partially in the downward direction. The impeller creates a draw that draws molten metal and any solid scrap metal contained therein downward into the molten metal bath. It also preferably provides at least some radial or partially radial flow, and may include a surface or structure specifically designed to generate radial or partially radial flow, to assist in circulating molten metal within the bath.

[0010]In another preferred embodiment, the impeller is preferably a four-bladed cross wherein each blade preferably includes a vertical surface that directs molten metal radially outward away from the impeller. The impeller creates a draw that draws molten metal and any solid scrap metal contained therein downward into the molten metal bath. It also assists in circulating molten metal within the bath.

[0011]A scrap melter according to the invention can be operated at lower speeds than conventional melters but still displace the same amount of molten metal per impeller revolution. Alternatively, it can be operated at the same speeds as, and displace more molten than conventional scrap melters. A benefit of the lower speed is that the scrap melter of the invention vibrates less and requires less maintenance and fewer replacement parts.

Problems solved by technology

However, such impellers can create turbulence or flow that may partially move into the path of the fluid entering the impeller from above, in which case some scrap may not be efficiently drawn into bath B where it can be melted and mixed, thus decreasing the fluid flow to the impeller and decreasing the efficiency of the scrap melting operation.

In addition, the radial turbulence may cause some fluid that has been expelled from the impeller to be immediately recirculated through the impeller, thus decreasing the flow of virgin fluid through the impeller.

That further decreases efficiency because it reduces the draw of molten metal from above the impeller.

Increasing the speed of the impeller, however, may cause excess vibration leading to part failure, downtime and maintenance expenses.

One disadvantage to this assembly is that pieces of scrap or dross can jam in it, which decreases its efficiency.

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