US20020089099A1

US20020089099A1 - Molten metal holding furnace baffle/heater system

Info

Publication number: US20020089099A1
Application number: US09/756,689
Authority: US
Inventors: Scott Denning; Russell Hale
Original assignee: Pyrotek Inc
Current assignee: Pyrotek Inc
Priority date: 2001-01-09
Filing date: 2001-01-09
Publication date: 2002-07-11

Abstract

Disclosed is a molten metal holding furnace system and a baffle and/or heater for use therein. The baffle/heater includes, among other things, a heat conductive body, at least one heater apertures and at least one passageways from a first side of the baffle body to the second side of the baffle body. Heaters within the heater apertures are isolated within the baffle body from the molten metal.

Description

TECHNICAL FIELD

This invention pertains to a molten metal melting or holding furnace baffle and heater system.

BACKGROUND OF THE INVENTION

Metal castparts such as aluminum castparts are typically manufactured by first smelting the raw components and then transferring the metal for casting. The casting process generally includes a melting or holding furnace, a degassing unit, filtration of the molten metal and then the casting of the metal into a desired shape. The metal may later be recast or shaped in its later handling. There may also be a secondary or scrap smelter to prepare the material to be placed in the melting or holding furnace.

In the melting or holding furnace, the material is either melted if it is not already in the desired molten state, or it is held, while heat is applied to maintain it in a desired molten state.

Molten metal from the melting or holding furnace may then be degassed in a degassing unit. In the degassing unit, impurities are removed from the molten metal through several known processes. The degassed molten metal is typically then filtered by known means before being cast into a desired solidified shape.

Molten metal may be one of the more difficult environments in which to maintain equipment such as heaters and pumps, due to the heat and the corrosive factors within the molten metal. The components of various systems which are submerged in the molten metal must therefore be specially designed to withstand the heat and corrosive effects of the molten metal environment.

In some typical holding furnaces, heat is applied through a plurality of smaller immersible heating units which are immersed into the top surface of the metal. Due to the difficult operating environment, the immersible heating units generally require frequent maintenance or replacement. Utilizing a plurality of these typical immersion heaters at or near the top of the surface level of the molten metal is also not as efficient as it could be in the heating of the metal or maintenance of the holding furnace. Further, typical immersion heaters intended to operate in this environment are substantially more expensive than heaters which may be used with this baffle system.

In other holding furnaces, radiant heaters are located in the furnace lid and radiate heat downward to the molten metal. These types of furnaces typically have excess oxide buildup both on the bath surface and on the furnace walls, which is detrimental to both metal quality and furnace life. Additionally, these types of furnaces may limit the practical depth of the molten metal in the furnace due to compensation for thermal losses. In some situations, the depth may be limited to eighteen inches despite a desire for a deeper furnace.

This invention is intended for use in the holding furnace or melting furnace and provides a new system through which heat may be applied to the metal being heated or melted, and/or which provides baffling.

It is therefore an object of this invention to provide an improved molten metal melting or holding furnace system.

BRIEF DESCRIPTION OF THE DRAWINGS

Preferred embodiments of the invention are described below with reference to the following accompanying drawings. [0010]
FIG. 1 is top view of one embodiment of a holding furnace system as contemplated by this invention; [0011]
FIG. 2 is a front elevation view of the embodiment of the holding furnace system shown in FIG. 1; [0012]
FIG. 3 is a side elevation view of the embodiment of the holding furnace system shown in FIG. 1; [0013]
FIG. 4 is a perspective view of the block/baffle utilized in the embodiment of the holding furnace system shown in FIG. 1; [0014]
FIG. 5 is a perspective view of another example of an alternative block/baffle which may be utilized in the embodiment of the holding furnace system shown in FIG. 1; [0015]
FIG. 6 is a side elevation view of the embodiment of the holding furnace system shown in FIG. 1, only with yet another example of an alternative block/baffle which may be utilized in combination therewith; and [0016]
FIG. 7 is a front elevation view of the embodiment of the holding furnace system shown in FIG. 1, with the holding furnace tilted to allow molten metal to be poured out of the holding furnace. [0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Many of the fastening, connection, manufacturing and other means and components utilized in this invention are widely known and used in the field of the invention described, their exact nature or type is not necessary for an understanding and use of the invention by a person skilled in the art or science, and they will not therefore be discussed in significant detail. Furthermore, the various components shown or described herein for any specific application of this invention can be varied or altered as anticipated by this invention and the practice of a specific application of any element may already be widely known or used in the art, or by persons skilled in the art or science, and each will not therefore be discussed in significant detail. [0018]
The terms “a”, “an” and “the” as used in the claims herein are used in conformance with longstanding claim drafting practice and interpretation and not in a limiting way. Unless specifically set forth herein, the aforementioned terms are not limited to one of such items but instead are intended to mean “at least one”. [0019]
While references may be made herein to molten aluminum, this is only used to give an example and not to limit the invention to molten aluminum systems since the invention disclosed herein may be used for other molten metals as well. [0020]
FIG. 1 is ta op view of one embodiment of a holding furnace system as contemplated by this invention, illustrating [0021] holding furnace 100, furnace containment walls 101, refractory or furnace lining 102, bottom furnace lining surface 102 a, side furnace lining walls 102 b, baffle 104 with baffle top side 104 a, baffle first side 104 b, baffle second side 104 c, heater apertures 105 in baffle 104, dip well 106 with dip well walls 103, charge well 107 shown with under pour funnel, and the interior cavity 108 of the holding furnace 100. Holding furnaces 100 are well known in the art.
FIG. 2 is a front elevation view of the embodiment of the holding furnace system shown in FIG. 1, illustrating [0022] holding furnace 100, furnace containment walls 101, side furnace lining walls 102 b, baffle, furnace lid 110, heater 117, heater apertures 105 in baffle 104, dip well 106 with dip well walls 103, charge well 107 shown with under pour funnel, spout 122, furnace base 120 and axis 121 about which the furnace may be rotated to pour or discharge molten metal (as shown more fully in FIG. 7).
The heater [0023] 117 may be any one of a number of different types of heaters known in the trade and depending on the specific circumstances of the furnace, preferably a radiant heater or a gas fired heater. No one type or kind of heater is required to practice the invention.
While the use of the [0024] furnace lid 110 is not necessary to practice this invention it is preferred as it assists in the control of the gases in the furnace.
FIG. 3 is a side elevation view of the embodiment of the holding furnace system shown in FIG. 1, illustrating [0025] heating furnace 100, furnace base 120, lid 110, furnace lining 102, heater apertures 105, insulation 125, baffle 104, first passageway 126 a and second passageway 126 b in baffle 104. It will be noted that while two passageways 126 a and 126 b are shown, one or more may be utilized in the practice of this invention, with no specific number required. As shown in FIG. 6 for example, there is only one passageway which spans across the entire span of the baffle 104.
It will further be noted that three [0026] heater apertures 105 are illustrated, one or more may be utilized in the practice of this invention, with no specific number required.
FIG. 4 is a perspective view of the block/baffle utilized in the embodiment of the holding furnace system shown in FIG. 1, and shows [0027] baffle 104 with top side 104 a, bottom side 104 f, first end 104 d, second end 104 e, first side 104 b, first passageway 126 a, and second passageway 126 b. In this embodiment, three heater apertures 105 are shown, first heater aperture 105 a, second heater aperture 105 b and third heater aperture 105 c, with second heater aperture 105 b being longer or deeper than the other two. It will be noted that there are numerous variations of heater aperture 105 sizes and configuration.
The [0028] baffle body 104 is preferably made of synthetic graphite, a manmade material which is made from petroleum coke for use in aluminum, an example of which may be grade CS114 available from Union Carbide. No one type of material or composition is required to practice the invention, and numerous types may be used, such as technical ceramics, silicon carbides, silicon nitrides, and others, all within the contemplation of this invention.
The [0029] baffle 104 will be sized to fit the application and may be in any one of a number of different external and internal shapes and configurations. One example of a size is wherein the baffle 104 is twenty nine inches high, thirty six and three-quarters inches long and ten and one-half inches thick. There is likewise no particular number of passageways or shapes of passageways are required to practice the invention.
FIG. 5 is a perspective view of another example of an alternative block/baffle which may be utilized in the embodiment of the holding furnace system shown in FIG. 1, showing a [0030] single passageway 126 a which only extends partially across the span of the baffle 104. All other components and items are as shown and described above with respect to FIG. 4.
FIG. 6 is a side elevation view of the embodiment of the holding furnace system shown in FIG. 1, only with yet another example of an alternative block/baffle which may be utilized in combination therewith. FIG. 6 shows a [0031] baffle 104 for a holding furnace 100, the baffle having one passageway 140 which spans the entire length of the baffle 104. FIG. 6 also shows heater apertures 105 in the heating block or baffle 104.
FIG. 7 is a front elevation view of the embodiment of the [0032] holding furnace 100 system shown in FIG. 1, with the holding furnace 100 tilted about tilt axis 121 to allow molten metal to be poured out of the holding furnace 100 through spout 122. Also shown in FIG. 7 are furnace containment wall 101, furnace lid 110 and furnace base 120.
As will be appreciated by those of reasonable skill in the art, there are numerous embodiments to this invention, and variations of elements and components which may be used, all within the scope of this invention. [0033]
One embodiment of this invention for example is a baffle for use in a molten metal holding furnace with an interior cavity for holding molten metal, the baffle comprising: a heat conductive baffle body with a first end, a second end, a first side, a second side, a top side and a bottom side, the baffle body being configured to span substantially across an interior cavity of a molten metal holding furnace at an intermediate location in the holding furnace; at least one heater aperture in the top side of the baffle body configured to receive at least one heater; such that the at least one heater is isolated from molten metal in the holding furnace; and at least one passageway between the first side and the second side of the baffle body, said at least one passageway being positioned through the baffle body such that when the baffle body is positioned within the holding furnace, molten metal may flow from one side of the baffle body to another side of the baffle body. [0034]
In addition to the foregoing, examples of further embodiments of the baffle would be for instance: wherein the at least one passageway is located below an intended level of the surface of molten metal in the holding furnace; wherein the baffle body is comprised of graphite; wherein the at least one apertures have a heater therein; and/or wherein there are two spaced apart passageways through the baffle body. [0035]
It will also be appreciated that there are molten metal holding furnace embodiments of the invention, such as wherein the molten metal holding furnace is comprised of: an insulated shell having bottom and side walls for containing molten metal and an internal cavity; a baffle comprised of: a heat conductive baffle body with a first end, a second end, a first side, a second side, a top side and a bottom side, the baffle body being configured to span substantially across the interior cavity of the insulated shell at an intermediate location in the holding furnace; at least one heater aperture in the top side of the baffle body configured to receive at least one heater; such that the at least one heater is isolated from molten metal in the holding furnace; and at least one passageway between the first side and the second side of the baffle body, said at least one passageway being positioned through the baffle body such that when the baffle body is positioned within the holding furnace, molten metal may flow from one side of the baffle body to another side of the baffle body. [0036]
In addition to the foregoing and similar to the examples given for the baffle, examples of further embodiments of the molten metal holding furnace include embodiments in which the baffle would be: wherein the at least one passageway is located below an intended level of the surface of molten metal in the holding furnace; wherein the baffle body is comprised of graphite; wherein the at least one apertures have a heater therein; and/or wherein there are two spaced-apart passageways through the baffle body. [0037]
Another embodiment is one in which the molten metal holding furnace further includes a lid over the top of the internal cavity of the insulated shell, the lid substantially sealing the internal cavity from the outside air. [0038]
In compliance with the statute, the invention has been described in language more or less specific as to structural and methodical features. It is to be understood, however, that the invention is not limited to the specific features shown and described, since the means herein disclosed comprise preferred forms of putting the invention into effect. The invention is, therefore, claimed in any of its forms or modifications within the proper scope of the appended claims appropriately interpreted in accordance with the doctrine of equivalents. [0039]

Claims

I/we claim:

1. A baffle for use in a molten metal holding furnace with an interior cavity for holding molten metal, the baffle comprising:

a heat conductive baffle body with a first end, a second end, a first side, a second side, a top side and a bottom side, the baffle body being configured to span substantially across an interior cavity of a molten metal holding furnace at an intermediate location in the holding furnace;

at least one heater aperture in the top side of the baffle body configured to receive at least one heater; such that the at least one heater is isolated from molten metal in the holding furnace; and

at least one passageway between the first side and the second side of the baffle body, said at least one passageway being positioned through the baffle body such that when the baffle body is positioned within the holding furnace, molten metal may flow from one side of the baffle body to another side of the baffle body.

2. A baffle as recited in claim 1, and further wherein the at least one passageway is located below an intended level of the surface of molten metal in the holding furnace.

3. A baffle as recited in claim 1 and wherein the baffle body is comprised of graphite.

4. A baffle as recited in claim 1 and wherein the at least one apertures have a heater therein.

5. A baffle as recited in claim 1 and further wherein there are two spaced-apart passageways through the baffle body.

6. A molten metal holding furnace comprised of:

an insulated shell having bottom and side walls for containing molten metal and an internal cavity;

a baffle comprised of:

a heat conductive baffle body with a first end, a second end, a first side, a second side, a top side and a bottom side, the baffle body being configured to span substantially across the interior cavity of the insulated shell at an intermediate location in the holding furnace;

7. A molten metal holding furnace as recited in claim 6, and further wherein the baffle body is graphite.

8. A molten metal holding furnace as recited in claim 6, and further comprising at least one heater in at least one heater aperture in the baffle body.

9. A molten metal holding furnace as recited in claim 6, and further comprising a lid over the top of the internal cavity of the insulated shell, the lid substantially sealing the internal cavity from the outside air.