Method and apparatus for manufacturing metal bars or ingots

Abstract

Method and apparatus for manufacturing metal bars or ingots. The abstract of the disclosure is submitted herewith as required by 37 C.F.R. §1.72(b). As stated in 37 C.F.R. §1.72(b): A brief abstract of the technical disclosure in the specification must commence on a separate sheet, preferably following the claims, under the heading “Abstract of the Disclosure.” The purpose of the abstract is to enable the Patent and Trademark Office and the public generally to determine quickly from a cursory inspection the nature and gist of the technical disclosure. The abstract shall not be used for interpreting the scope of the claims. Therefore, any statements made relating to the abstract are not intended to limit the claims in any manner and should not be interpreted as limiting the claims in any manner.

Description

BACKGROUND[0001]1. Technical Field[0002]Small diameter bars, and small ingots, sometimes referred to as pig ingots, or concast bars are used throughout many segments of the metals industry. These small bars and ingots (SBI), weigh approximately twenty pounds and are frequently used as raw materials for investment and sand casting foundries, and die casting foundries. They are also used for alloy additions in other melting facilities such as steel mills and vacuum induction furnaces (VIM).[0003]2. Background Information[0004]Background information is for informational purposes only and does not necessarily admit that subsequently mentioned information and publications are prior art.[0005]The traditional manufacturing systems for producing these small ingots and bars are fairly limited and comprise some adverse process characteristics including negative health and environmental impacts, reduced manufacturing flexibility, increased manufacturing costs, and in some cases, poor ingot qua...

AI Technical Summary

Benefits of technology

[0048]The process according to at least one possible embodiment of the present application addresses the undesirable problems associated with these other processes. In addition, the method of the present application offers flexibility and high quality, improved operating costs, and significantly reduced environmental concerns.

[0050]1. A holding tundish which includes insulated walls and floor, an emergency inductive heater controlled by an electric power supply and automated control system, controlled heating by use of an induction coil connected to a power supply, an automated control system, an insulated lid with ports for continuous temperature monitoring and ports for backfill flooding with an inert gas such as argon; continuous temperature monitoring equipment, a spout, screw jacks, and either linear position transducers, LPT, or encoders, which are used to precisely or substantially precisely control the tilting of the tundish;

[0058]The combination of the holding tundish, pouring vessel, mold system, and conveyor system creates a process whereby the products produced are of exceptional quality and have a high cleanliness and size control. As the result of precise or general temperature control and protection of the metal bath from re-oxidation, this process yields itself to the production of a wide range of alloy types.

Problems solved by technology

The traditional manufacturing systems for producing these small ingots and bars are fairly limited and comprise some adverse process characteristics including negative health and environmental impacts, reduced manufacturing flexibility, increased manufacturing costs, and in some cases, poor ingot quality.

It also provides some limited protection to the mold during casting.

Both permanent and sand cast ingots are prone to developing blow holes in the tops and side walls of the ingots.

The permanent mold system is prone to developing blow holes due to an out gassing effect from the mold wash and moisture left from the water spray.

Other sources of contamination include the mold wash, oxidation formed as the result of the molten metal being exposed to open air during the pouring process, and shot that may become entrapped in blow holes during tumble blast cleaning operations.

Contamination and oxide formation in and around blow holes is a chronic problem.

The presence of such contaminates can result in increased production costs and higher rejection rates for the foundry using the pig ingots to produce castings.

During pouring with the PMC system there is also the potential to form metal fins across the tops of adjacent ingots.

The formation of these metal fins tends to be more severe when casting grades that have high ductility.

This adds additional labor cost and potentially lower yields for the producer.

The permanent mold pig casting process has a number of undesirable attributes.

Poor ingot quality, waste, and reduced good product yields when compared to other methods.

Additional undesirable environmental and cost concerns may be created from the need or desire to properly dispose of the mold wash materials and contaminated sprayed cooling water.

Oxide is a major source of contamination in the ingot and increases the likelihood of scraped castings.

Having a precise or general control of the molten stream during the pour is rather difficult and rather time consuming.

Since metal is simply top poured into the molds, the process is relatively simple, but like the permanent mold process, there are numerous undesirable aspects which can occur.

As mentioned earlier, sand cast ingots often develop blow holes.

They also commonly comprise internal voids which form as the result of uncontrolled cooling.

In addition, the molds may break apart before the molten metal has solidified.

As a result, additional loose mold sand becomes a source of contamination in the ingot.

However, these alternative consumable mold products have had limited success.

The alternative molds have been prone to leaking metal during the casting operation and thus become another potential source for contamination.

Increased manufacturing consumable costs, product size variability, poor ingot quality, concerns about potential hazards from the presence of free silica dust in the workplace, and increased labor requirements are adverse factors for this process.

The proper disposal of spent sand molds may also increase costs for the producer.

The binders in the molds often emit a strong and unpleasant odor and fumes are created from both the holding tundish, or furnace, and the molds during pouring.

Producing small bars by this method is very time consuming and labor intensive.

Metal may freeze when traveling through the refractory system and the pour must or should be aborted.

The metal may also leak out the refractory system or the ingots may become stuck in the molds.

Set up and tear down requires or desires excessive labor time.

High consumable refractory and disposal costs, combined with poor yields and excessive labor costs are negative aspects of the BPI process when it is used to produce small bars.

There are a large number of variables which can affect the success of the cast and the quality of the bars.

Too hot, and the liquid metal can “run out” of the die.

Casting rates, temperature control, and differences in solidification properties between various grades can limit the grades that can be successfully cast with the continuous casting process.

The initial machine and start up costs with this process can be quite expensive.

Although the cutting of the bars can be automated to reduce the labor costs, the good product yields are negatively impacted when cutting small size bars for remelting applications.

Another undesirable element is that concast process has limited flexibility.

Also, since the set up costs between runs can be expensive and time consuming, the production and consumable costs can be high for a producer who needs or desires to change grades or change sizes.

Product diameter changes are somewhat limited and expensive due to mold and die costs, and the need or desire to maintain a precise or general alignment between the molds and drive motors.

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