HK1126032A - Channel electric inductor assembly - Google Patents

Description

Channel electric inductor assembly

Technical Field

The present invention relates to a channel electric inductor assembly for use in a vessel for melting or heating an electrically conductive liquid material, such as molten metal.

Background

The channel electric inductor assembly may be used with a vessel that holds molten metal in an industrial process. Fig. 1(a) shows a cross-sectional view of a typical channel electrical inductor assembly 110. The housing 112 generally provides structural support for the assembly. A heat resistant material 114 is provided along the inner wall of the shell to insulate. The generally cylindrical shaped sleeve 116 serves as an outer housing for the coil and core assembly containing the inductor coil 118a and the transformer core 118 b. The sleeve 116 provides support and cooling for the refractory wall 114 surrounding the coil and core assembly. A heat resistant material 114 is provided along the outer wall of the sleeve for thermal insulation. The space between the refractory material adjacent the inner wall of the shell and the refractory material surrounding the sleeve forms a metal flow channel. The channel electrical assembly shown in fig. 1(a) is referred to as a single loop type because the metal flows around the single loop formed by the coil and core assembly in the sleeve 116. When an ac current flows through inductor 118a, the conductive metal is inductively heated and passes through the flow path of the loop in the direction of the arrows shown, for example, in fig. 1 (a). The channel electric inductor assembly 110 is typically connected to a vessel 130 (also referred to as an upper box) for holding molten metal as shown in fig. 1 (b). The container may be formed by a structural support outer wall 132 with a heat resistant material 134 suitably provided along the structural support outer wall 132. By circulating metal from the vessel 130 through the flow path of the loop, the metal in the vessel 130 can be heated or maintained at a desired processing temperature for use in industrial processes. For example, the metal in the container may be a zinc composition and a metal strip may be dipped into the container so that the zinc covers the metal strip.

In the manufacture of channel electric induction assemblies, not only must flow channels be created, but also flow channel boundary walls containing porous refractory material must be properly prepared to prevent infiltration of molten metal into the refractory material. Typically, heat resistant wall materials are often sintered; that is, the refractory walls of the flow channel are heated at a sufficiently high temperature that is below the melting point of the refractory composition but that can bond the grains of refractory material together at the interface walls to form a boundary that is substantially impermeable to the molten metal passing through the flow channel. The conventional way to accomplish the formation of the flow channel and the sintering of the heat resistant wall material is to use a combustible channel mold, such as a mold formed of wood, for the flow channel. The mold is shaped to conform to the space of the flow channel of the circuit. After installing a heat-resistant material around the combustible channel mold, the mold is ignited by combustion and burned off to remove the mold, and the heat of combustion is used to sinter the heat-resistant walls of the flow channel. This is referred to as using a combustible mold. A disadvantage of this method is that the firing rate over the entire space of the channel mould is often not controllable. The degree of sintering of the refractory walls along the entire flow channel is therefore not of uniform quality and results in local areas of the refractory walls being improperly sintered. Infiltration of molten metal from the flow channels into the refractory 114 can result in metal leakage to the outer shell and/or inductor coil and core assembly, which can cause premature failure of the channel electrical inductor assembly.

The non-detachable channel mould may be formed, for example, from a conductive metal. After the channel electric inductor assembly is assembled with the conductive metal in the space where the flow channel is to be formed, ac current is applied to inductor coil 118a to inductively melt the conductive channel mold. The disadvantage of this method is that the electric induction heating and melting of the conductive metal mold makes it difficult to reach the sintering temperature of the heat-resistant material before the mold melts. Furthermore, the mould may be formed from welded parts, the rapid induction melting of the weld causing the parts of the mould to be induction melted in an irregular manner. Accordingly, there is a need for a channel electric inductor assembly that utilizes a non-removable channel mold that can be used to properly sinter the refractory walls of the flow channel and then satisfactorily removed.

Disclosure of Invention

In one aspect, the present invention is a channel electric inductor assembly having a non-removable channel mold formed of a hollow substantially non-magnetic component.

In another aspect, the present invention is a method of forming a channel electric inductor assembly. A non-removable hollow and substantially non-magnetic channel mold is disposed in the space forming one or more flow channels of the assembly. The heated fluid medium is circulated inside the hollow mold to heat the walls of the mold, thereby generally heating the refractory walls outside the mold by heat conduction from the mold walls to heat-treat the refractory walls. A charge of material is provided to the interior of the hollow mold to chemically dissolve the mold. The AC current flowing through the one or more inductors of the assembly may utilize the electromagnetic properties to circulate the charge and dissolved mold within the flow channel to form one or more flow channels having sintered walls.

The above and other aspects of the invention are further set out in the present description and the appended claims.

Drawings

For the purpose of illustrating the invention, there is shown in the drawings a form that is presently preferred; it should be understood, however, that the invention is not limited to the precise arrangements and instrumentalities shown.

Fig. 1(a) shows a cross-sectional view of a typical single-circuit channel electric inductor assembly, and fig. 1(b) shows the inductor assembly of fig. 1(a) connected to a vessel for holding molten metal.

Figure 2 is a cross-sectional view of one example of a channel electrical inductor assembly of the present invention.

Fig. 3(a) and 3(b) show an example of a non-removable channel die used in the channel inductor assembly of the present invention.

Fig. 4(a), 4(b) and 4(c) are cross-sectional views taken along line a-a in fig. 2 and illustrate one example of a method of making a channel electrical inductor assembly of the present invention.

Figure 5 shows one arrangement for providing heated fluid medium to the hollow interior of a channel die for use in the channel electric inductor assembly of the present invention.

Detailed Description

Figure 2 shows one example of a channel electrical inductor assembly 10 of the present invention. Although the channel electric inductor assembly is shown as a dual loop type (i.e., two flow channels surrounding two inductor coils and a core assembly, each assembly in a separate casing), the invention is not limited to the number of loops and the channel electric inductor assembly may have a single loop or more than two loops.

The inductor assembly 10 includes a housing 12; a refractory material 14 disposed at least partially along the inner wall of the shell; two bushings 16 in which two inductor coil and core assemblies (each including an inductor coil 18a and a transformer core 18b) are respectively located; a heat resistant material 14 surrounding the outer surface of the sleeve 16; and a hollow non-magnetic metal channel mold 24 located in the space serving as the dual-circuit flow channel. Fig. 3(a) and 3(b) show one non-limiting example of a mold 24, where fig. 3(a) (with dashed lines) shows the interior features of the mold and fig. 3(b) shows the exterior of the mold design. In this non-limiting example, the mold 24 has two open cylindrical tubes 24a in which the heat resistant material 14, the sleeve 16, and the coil and core assembly are disposed. The space between the outer surface of the tube and the inside of the outer wall of the mold (e.g., wall regions 24b, 24c, and 24d) forms the hollow interior space of the mold. The top of the mold 24 may be generally open and one or more cross-brace elements 24e may be provided across the top of the mold, if desired. The mold is formed of a non-magnetic material such that the mold is generally not melted by electric induction when an ac current is applied to coil 18 a. The composition of the mold is selected such that the mold is chemically dissolved by reaction with a liquid introduced into the hollow space of the mold as described further below. The mold 24 may be of other shapes suitable for the desired location and spacing of the flow channel or channels to be formed by the mold. For example, the die may be formed to provide a flow passage of generally elliptical rather than rectangular cross-section around a selected region of the one or more sleeves. The minimum wall thickness of the hollow mold is generally selected to provide sufficient structural integrity of the mold and sufficient thermal conductivity characteristics from the mold to the heat resistant material surrounding the outside of the mold as further described below.

One non-limiting method of forming a channel electric inductor assembly of the present invention is described with reference to fig. 4(a), 4(b) and 4(c), wherein the formation of the inductor assembly is accomplished by first placing the inductor assembly on its side. Referring to fig. 4(a), an outer shell, which may be formed of structural steel, first has a horizontally oriented first shell side wall 12a and a vertically oriented shell bottom 12 c. One or more sleeves 16 may be placed in the housing in the desired position shown in fig. 4 (a). The temporary structural wall 96 may be used to contain the refractory 14 within the channel electric inductor assembly until it is turned to an upright position after assembly. X may be formed on the inner side of the first case side wall 12a₁A highly heat resistant material 14. If a dry refractory material is used, the refractory material may be compacted (charged) by vibration as it is gradually added using, for example, a compacting tool.

Referring to fig. 4(b), the mold 24 is placed into a space that forms one or more flow channels as will be described further below. Voids may be present between the inner surface of housing bottom 12c and the outer wall of the mold and between the outer surface of sleeve 16 and the outer wall of the moldWith intermediate addition of refractory material 14 to height x₂If necessary, further compaction is performed, for example, using dry refractory material.

Referring finally to fig. 4(c), refractory 14 may be added to height x over the top of mold 24₃Further compaction may be performed, if desired, and the opposite shell side wall 12b of the shell may be mounted to the assembly. The channel electric inductor assembly may then be rotated to an upright position with housing bottom 12c oriented horizontally, and temporary structure 96 may be removed from the top of the inductor assembly. Optionally, the open end of one or more sleeves may extend outside of the side walls 12a and 12b as shown in fig. 4(a), 4(b) and 4(c) so that the inductor coil and core assembly may be inserted into or removed from its sleeve after assembly of the channel electrical inductor assembly is completed. The inductor coil and core assembly may be installed in each of the one or more bushings at any suitable step in the assembly of the channel electric inductor assembly.

An alternative but non-limiting method of forming a channel electric inductor assembly of the present invention comprises the steps of: the mold 24 and sleeve 16 are first inserted into the erected shell 12 (with side panels 12b installed) and held in place with temporary support structures, while a heat resistant material is poured into the space between the outer surface of the mold and the shell 12 and sleeve 16. If desired, the entire housing containing the mold and sleeve may be vibrated as refractory material is added to the space, or alternatively, in combination therewith, vibration of the refractory material may be accomplished using a compaction tool, if desired.

After forming the channel electric inductor assembly of the present invention as described above, the refractory material adjacent the outer wall of the mold is heat treated. For heat treatment of refractory material adjacent the outer walls of the mold, a heated fluid medium, liquid or gas, is circulated within the hollow interior of the mold 24 to heat treat the refractory material that will form the bounding walls of the one or more flow channels. The term "heat treatment" as used herein refers to any heating process that causes the refractory material adjacent the outer wall of the mold to bond to form a substantially impermeable boundary to the material to be flowed within the flow channel. Typically, this may be a sintering process, although the heat treatment depends on the particular type of heat resistant material used in the application. The electric channel inductor assembly can be sintered in any orientation; however, in this example, reference is made to FIG. 5, wherein the inductor assembly is shown in an upright position. The normally open top area of the mold may be temporarily sealed with a cover 30. A suitably heated fluid medium, such as air, may be introduced into and through the hollow core of the mold, for example, using a fluid pump. The fluid pump may be a jet pump (using the venturi effect to create a vacuum). For example, as shown in fig. 5, one or more jet pumps 32 and 33 may be provided at the top of the mold for introducing heated air into and through the hollow space of the mold via the cover 30. The heated air is provided via one or more openings 34 in the lid. A suitable jet working fluid medium is supplied to the working inlet 32a and 33a of each jet pump which draws supplied air from the inlets 32b and 33b to the outlets 32c and 33c respectively by the venturi effect, thereby drawing heated air through the hollow of the mould as diagrammatically indicated by the arrows in figure 5. A conduit extending from the one or more openings 34 into the hollow of the mold introduces heated air into the hollow of the mold. The flow of heated air through the hollow interior of the mold heats the mold by convection, and the heated mold generally heats the heat resistant material disposed outside the mold walls by convection. One or more suitable temperature sensing devices, such as thermocouples, may be mounted within the hollow interior of the mold to monitor the temperature at selected points during the heat treatment process to ensure that the proper heat treatment temperature of the refractory material is achieved in selected areas. Alternatively, the temperature sensing device may be embedded in the mold or mounted on the outer wall of the mold. A heat treatment parameter, such as the temperature or flow pressure of the heated fluid medium, may be adjusted in response to the sensed temperature. For example, if the temperature sensing device indicates low heat in loop a and high heat in loop B, the jet pumps 32 and 33 may be adjusted to produce higher and lower flow rates through the pumps, respectively, so that higher heat transfer is achieved in loop a than in loop B. The heat treatment process is continued until the boundary walls of the flow channel have been sintered. Alternatively, the heat treatment process may be performed after the channel electric inductor assembly is mounted to its upper cabinet, and the top of the upper cabinet may be temporarily sealed rather than the top of the electric inductor assembly to form a boundary for the flow of heated medium into and out of the hollow interior of the mold as described above. Although a jet pump is used in the non-limiting example of the invention, other types of fluid flow control devices may be used in other examples of the invention.

After heat treating the refractory walls of the flow channels, the cover 30, temperature sensing means (if used), and associated fluid medium circulation apparatus may be removed and a charge of electrically conductive molten metal may be supplied to the hollow interior of the mold 24 to chemically dissolve the mold, preferably while an ac current is supplied to the one or more inductors 18 so that when the hollow mold dissolves into the molten metal, it is removed from the flow channels by the electromagnetically induced flow of the electrically conductive molten metal, leaving a substantially uniform heat treated refractory wall around the open flow channels.

Typically, but not necessarily, the electrically conductive molten metal charge used to chemically dissolve the hollow molds is a composition similar to that used by the electric channel inductor assembly for melting or heating molten metal in the upper enclosure; thus, the composition of the hollow mold is selected based on the properties of the conductive molten metal to ensure that the mold is chemically dissolved in the molten metal. By way of example, but not limitation, when the conductive molten metal charge is zinc or a zinc/aluminum composite, such as the metals used in electroplating processes, then the hollow non-magnetic via mold may be constructed of an 1/4 inch sheet formed of aluminum standard alloy 6061-O (untempered) of the aluminum association, which is an aluminum composite with the lowest trace constituents of silicon, copper, magnesium, and chromium, having sufficient tensile strength to function as a via mold. In these examples, essentially the aluminum mold is chemically dissolved in the molten metal.

In other examples of the invention, the liquid charge need not be a metal composition, but may be any other electrically conductive fluid material that acts as a chemical solvent for the hollow mold and does not contaminate the flow channels.

In other examples of the invention, the liquid charge may be a non-conductive fluid material in which the hollow mould is to be dissolved. After the mold is dissolved, conductive material is supplied to the flow channel for mixing with the non-conductive material in which the hollow mold has been dissolved, and ac current is supplied to the one or more induction coils 18a to remove the conductive material from the flow channel.

The term "refractory" as used herein may be any material used to provide a form-independent refractory lining, which may include, but is not limited to, dry bulk particulate material that may be vibrated or packed into place, and a casting comprised of dry pellets and a binder that may be mixed with a liquid and poured into place.

Although one die is used in the above example of the invention, two or more dies may be used to form multiple flow loops along the length of the channel electric induction furnace, each flow loop being separated from the other by a refractory material.

The above examples of the present invention are provided for illustrative purposes only and are not intended to limit the present invention in any way. While the invention has been described in connection with various embodiments, the words which have been used herein are words of description and illustration, rather than words of limitation. Although the present invention has been described herein with reference to particular means, materials and embodiments, the present invention is not intended to be limited to the particulars disclosed herein; rather, the invention extends to functionally equivalent structures, methods and uses, such as are within the scope of the appended claims. Those skilled in the art, having the benefit of the teachings of this specification, may effect numerous modifications thereto and changes may be made without departing from the scope of the invention in its aspects.

Claims (18)

1. In an electrical channel inductor assembly comprising a housing having one or more bushings disposed therein and a heat resistant material between said housing and said one or more bushings, an inductor coil and core assembly housed in each of said one or more bushings, the improvement comprising:

a hollow, non-magnetic channel mold conforms to the shape of the one or more flow channels, is disposed in the refractory material between the housing and the one or more sleeves and is formed of a composition that does not deform at the refractory material heat treatment temperature, and is chemically soluble in the material provided to the hollow interior of the mold.

2. A method of forming an electrical channel inductor assembly comprising the steps of:

placing a hollow, non-magnetic channel mold conforming to the shape of the one or more flow channels between the inner wall of the assembly and the one or more sleeves;

installing a heat resistant material between the outer surface of the hollow, non-magnetic channel mold and the inner wall of the assembly and the outer surface of the one or more sleeves; and

circulating a heated fluid medium through the hollow interior of the mold to heat the walls of the mold to heat treat the refractory material adjacent the outer surface of the hollow channel mold to form sealed refractory material walls.

3. The method of claim 2, wherein the heat treatment is sintering.

4. The method of claim 3, wherein the step of circulating the heated fluid medium comprises drawing the heated fluid medium through the hollow interior of the mold with one or more jet pumps.

5. The method of claim 4, further comprising the steps of: sensing the temperature of the mould wall at one or more points, analysing the temperature sensed at the one or more points; and adjusting a parameter of the heated fluid medium in response to the sensed temperature at the one or more points.

6. The method of claim 5, wherein the step of adjusting the parameter of the heated fluid medium in response to the temperature sensed at the one or more points is accomplished by adjusting the fluid flow rate through the one or more jet pumps.

7. The method of claim 2, further comprising the steps of: providing a liquid to the hollow interior of the mold to chemically dissolve the hollow mold.

8. The method of claim 7, further comprising the steps of: providing an alternating current to an induction coil disposed in each of the one or more sleeves to remove the liquid from the electrical channel inductor assembly.

9. A method of forming an electrical channel inductor assembly comprising the steps of:

forming a housing for the assembly;

placing one or more sleeves in the assembly;

placing a hollow, non-magnetic channel mold conforming to the shape of the one or more flow channels between the inner wall of the housing and the outer surface of the one or more sleeves, the outer wall of the mold being spaced apart from the inner wall of the housing and the outer surface of the one or more sleeves to form a refractory space; and

a heat-resistant material is installed in the heat-resistant material space.

10. The method of claim 9, further comprising the steps of: circulating a heated fluid medium through the hollow interior of the channel mold to heat the walls of the mold to heat treat the refractory material adjacent the outer surface of the hollow channel mold to form sealed refractory material walls.

11. The method of claim 10, wherein the heat treatment is sintering.

12. The method of claim 10, wherein the step of circulating the heated fluid medium comprises drawing the heated fluid medium through the hollow interior of the mold with one or more jet pumps.

13. The method of claim 10, further comprising the steps of: sensing the temperature of the mould wall at one or more points, analysing the temperature sensed at the one or more points; and adjusting a parameter of the heated fluid medium in response to the sensed temperature at the one or more points.

14. The method of claim 13, wherein the step of adjusting the parameter of the heated fluid medium in response to the temperature sensed at the one or more points is accomplished by adjusting the fluid flow rate through the one or more jet pumps.

15. The method of claim 10, further comprising the steps of: providing a conductive liquid to the hollow interior of the mold to chemically dissolve the hollow mold.

16. The method of claim 15, further comprising the steps of: providing an alternating current to an induction coil disposed in each of the one or more sleeves to heat the electrically conductive liquid and create a flow of the electrically conductive liquid to remove the dissolved hollow mold from the one or more flow channels.

17. The method of claim 10, further comprising the steps of: providing a liquid to the hollow interior of the mold to chemically dissolve the hollow mold.

18. The method of claim 17, further comprising the steps of: providing an alternating current to an induction coil disposed in each of the one or more sleeves to remove the conductive liquid from the electrical channel inductor assembly.