This application relates to support and compression assemblies for use with curvilinear devices for containing, stirring and/or conveying molten metal.
To form a metal ingot, which is metal material cast into a suitable shape for use in various applications, metal is heated past its melting point in a furnace. Typically, the molten metal is composed of two or more materials and therefore it is important that the molten metal be sufficiently mixed to produce an ingot having a uniform structure.
Molten metal may be routed out of the furnace or other structure, mixed thoroughly, and routed back into the furnace or other structure to mix the molten metal before it solidifies. In some cases, the molten metal flows out of the furnace and back into the furnace along a curvilinear or other shaped metal transfer structure. As the molten metal moves through the metal transfer structure, the molten metal is agitated and therefore mixed. In some applications, mixing occurs using magnetic fields, such as is taught by U.S. Pat. No. 8,158,055, which issued on Apr. 17, 2012 and is incorporated herein by reference.
The described curvilinear metal transfer structures can be used in any suitable application and with any desired structure. As one additional non-limiting example, a metal transfer structure can be used to connect a furnace to a separate structure to facilitate the conveyance of molten metal between the furnace and the separate structure.
One non-limiting example of a curvilinear metal transfer structure includes a refractory housed within an outer metal casing. The molten metal, as well as combustion gases, flames and other high temperature materials, contact the refractory and therefore the refractory must have a high melting point and otherwise be capable of withstanding the high temperatures of the molten metal. The refractory insulates the outer metal casing from the molten metal to help prevent the operating temperature of the outer metal casing from reaching unsafe levels. An air gap and/or insulation may be provided between the outer metal casing and the refractory.
The refractory in contact with the molten metal typically becomes extremely hot and in some cases reaches temperatures of around 750° C., and combustion gases can heat the surface of the refractory in excess of 1200° C. Transfer of heat from the refractory to the outer metal casing causes the metal casing to heat to high temperatures during operation. As temperatures at the outer casing and the refractory change, the two components expand and contract. If the components expand and/or contract at uneven rates, distortion may occur, which can cause gaps from which the molten metal may leak. Moreover, because of the curvilinear nature of the metal transfer structure, the inner wall of the refractory is shorter than the outer wall of the refractory and thus expands less than the outer wall as the refractory heats up. Similarly, the inner wall of the outer casing is shorter than the outer wall of the outer casing and thus expands less than the outer wall as the outer casing heats up. The dissimilar heating of the inner walls versus the outer walls creates a mechanical puzzle that must be solved so that, as the refractory heats and expands, the outer casing can remain dynamic and retain its structural integrity over multiple heating and cooling cycles.
The terms “invention,” “the invention,” “this invention” and “the present invention” used in this patent are intended to refer broadly to all of the subject matter of this patent and the patent claims below. Statements containing these terms should be understood not to limit the subject matter described herein or to limit the meaning or scope of the patent claims below. Embodiments of the invention covered by this patent are defined by the claims below, not this summary. This summary is a high-level overview of various aspects of the invention and introduces some of the concepts that are further described in the Detailed Description section below. This summary is not intended to identify key or essential features of the claimed subject matter, nor is it intended to be used in isolation to determine the scope of the claimed subject matter. The subject matter should be understood by reference to appropriate portions of the entire specification of this patent, any or all drawings and each claim.
This patent discloses a curvilinear metal transfer device with various support and compression assemblies that help maintain a constant force on the curvilinear metal transfer device's metal outer casing and refractory as the inner and outer surfaces of the outer casing and refractory expand and contract due to temperature fluctuations and the significant stresses placed on the curvilinear metal transfer device as the materials heat up and cool down. In particular, the support and compression assemblies apply force to the refractory to keep the refractory in compression with the outer casing to suspend the refractory relative to the outer casing. In this way, the support and compression assemblies accommodate different expansion and contraction rates of the outer casing and the refractory by allowing for selective expansion and compression of the refractory relative to the outer metal casing.
Illustrative embodiments of the present invention are described in detail below with reference to the following drawing figures:
The subject matter of embodiments of the present invention is described here with specificity to meet statutory requirements, but this description is not necessarily intended to limit the scope of the claims. The claimed subject matter may be embodied in other ways, may include different elements or steps, and may be used in conjunction with other existing or future technologies. This description should not be interpreted as implying any particular order or arrangement among or between various steps or elements except when the order of individual steps or arrangement of elements is explicitly described.
Disclosed herein is an improved curvilinear metal transfer device for conveying molten metal into and out of a furnace or other structure. While the molten metal is conveyed through the curvilinear metal transfer device, the molten metal can be agitated to help achieve uniformity throughout the liquid. The curvilinear metal transfer device includes a plurality of support and compression assemblies that support a refractory within a metal casing. Specifically, the support and compression assemblies are configured to account for the fact that the refractory and the metal casing, and the inner and outer walls of the refractory and metal casing, do not expand and contract uniformly; therefore, the support and compression assemblies help maintain the structural integrity of the refractory and the casing.
Furnace 1 may be a single chamber furnace or have more than one chamber. For example, as illustrated in
As shown in
In embodiments, the molten metal can be agitated or otherwise mixed while the metal flows through the metal transfer device 10. For example, magnetic fields can be used to stir the molten metal. As an example, as shown in
A furnace such as furnace 1 is typically very large; in some cases it has an exterior diameter of around 40 feet and can hold around 125 tons of molten metal; however, furnaces of varying dimension and capacity are within the scope of this description, and the aforementioned dimensions are exemplary only and not intended to be limiting. Since the metal transfer device 10 is bolted or otherwise attached to the side of the furnace, the furnace will cause the outer metal casing with which it is in contact to expand and contract as the furnace heats up and cools back down. It is important that the metal transfer device 10 be able to expand and contract uniformly along the radial surface to maintain its structural integrity against the pressure and the corrosive nature of the molten metal while still being strong enough to withstand the heavy loads of the molten metal.
During operation of the furnace, the side of the refractory exposed to the molten metal typically has an average temperature of between 700-750° C., while the opposite side of the refractory (the side facing the metal casing) has a significantly lower temperature of around 400-500° C. During the melting cycle, various gases may bring the surface temperature of the refractory up to around 1200° C. If the temperature of the side of the refractory in contact with the metal casing is higher than the temperature of the outer casing, the metal casing will heat up. In this way, the temperature of the refractory 22 and the outer casing 24 is extremely dynamic.
Typically, the linear coefficient of expansion of the refractory 22 is different from the linear coefficient of expansion of the outer metal casing 24, which causes the refractory 22 to expand and contract at a different rate than the outer metal casing 24. Similarly, the relatively shorter curvilinear (e.g., arc-radial) inner wall 21 of the refractory 22 expands less than the relatively longer curvilinear outer wall 23 of the refractory. Gaps may form in either or both the refractory and the metal casing if the refractory does not expand and contract at the same rate as the outer metal casing and/or if the inner wall 21 of the refractory does not expand and contract at the same rate as the outer wall 23. If these cracks form, molten metal can leak and cause burn risks and other hazards. Along these same lines, if the refractory 22 and metal casing 24 heat and cool at different rates, one or both of the structures may buckle and be subjected to cracks or other structural defects, risking leakage of potentially high volumes of molten metal. The heat and cooling cycles are particularly destructive, as the forces during these cycles are even more significant than the forces associated with normal use.
To accommodate the different linear coefficients of expansion of the casing 24 and the refractory 22 while still providing the necessary support for the metal transfer device 10 to support large loads, support assemblies 26 are positioned radially along the metal transfer device 10 to suspend the refractory 22 away from the outer casing 24. As shown in
As shown in
The fastener 32 includes a distal abutment surface 52 and external threads 54. An axially aligned sleeve 56 extends from the distal side of the fastener 32 and is shaped to receive the axial extension 51 of the cap 46. The fastener 32 includes a tool receiving pattern, such as a hex pattern 58, on a proximal side.
The support assembly clamp plate 34 is installed on the outer casing 24 by the clamp plate fasteners 37. The cap 46 is seated on the push rod 30, and the push rod 30 is inserted into the aperture 35. The spring washers 28 are installed on the axial extension 51, and the axially aligned sleeve 56 is fitted over the end of the axial extension 51 so that the abutment surface 52 engages the proximal side of the closest spring washer 28. The opposite side of the washers 28 engages a shoulder surface 53 of the cap 46.
The fastener 32 is threaded, via the external threads 54, into internal threads 60 in the aperture 35. A tool (not shown) is fitted onto the tool receiving pattern 58, and the fastener 32 is driven into the aperture 35. The fastener 32 pushes the spring washers 28, which in turn press the push rod 30, via the cap 46, into contact with the refractory 22. The fastener 32 is tightened to press the push rod 30 into engagement, but not tight engagement that would cause full compression of the spring washers. The resiliency of the spring washers 28 keeps the push rod 30 resiliently pressed against the refractory 22, but the push rod can move inward, against the bias of the spring washers, as a result of expansion of the refractory 22. In some embodiments, the fastener 32 can be partly tightened so as to allow expansion and contraction of the refractory 22 relative to the outer casing 24.
As shown in
In some embodiments, the support assembly 26 is positioned so that the support assembly clamp plate 34 is attached to the outer casing 24, with the push rod 30 extending through the aperture 35 in the support assembly clamp plate 34 and an aperture in the outer casing 24 so that distal end 38 of the push rod 30 engages the refractory 22. Fastener 32 may be tightened to apply compressive torque that translates to a force sufficient to suspend the refractory 22 relative to the metal casing 24. In particular, the ends of each support assembly 26 generate equal and opposite forces to hold the refractory 22 in place relative to the metal casing 24. In this way, the support assemblies 26 apply a force to the refractory 22 to compress the refractory 22 in an axial direction.
As described above, spring washers 28 (sometimes referred to as Belleville washers) engage the push rod 30 and act as a spring to maintain a constant force on the lower surface of the refractory 22 regardless of the temperature changes and corresponding expansion or contraction of the outer casing 24 or the refractory 22. If the refractory 22 expands relative to the outer casing 24, applying compressive force to the support assembly 26, the spring washers 28 compress to allow limited movement of the push rod 30 to accommodate the expansion without a corresponding movement on the other end of the support assembly. Similarly, if the refractory 22 contracts relative to the outer casing 24, the spring washers 28 expand to allow limited movement of the push rod 30 inward toward the refractory to accommodate the compression without a corresponding movement on the other end of the support assembly.
In this way, the support assemblies 26 help maintain a constant force between the metal outer casing 24 and the refractory 22 as the outer casing 24 expands and contracts as the refractory 22 expands and contracts. As a result, the support assemblies 26 allow the curvilinear metal transfer device 10 to behave like an accordion and accommodate different expansion and contraction rates of the outer casing 24 and the refractory 22. Support assemblies 26 accomplish this by keeping the refractory 22 in tension with respect to the outer metal casing 24 and allowing for selective expansion and compression of the refractory 22 relative to the outer metal casing 24.
Specifically, one end of each support assembly 26 pushes against the outer casing 24 and the other end of the support assembly 26 pushes against the refractory 22 to suspend the refractory 22 relative to the outer casing 24. The one or more spring washers 28 translates forces applied from either the outer casing 24 or the refractory 22 to the push rods 30 to ensure that the refractory 22 is suspended relative to the outer casing regardless of temperature fluctuations.
As shown in
Specifically, as shown in
As shown in
As shown in
The various support and compression assemblies and clamp plates disclosed above allow for selective compression and expansion of the refractory 22 and outer casing 24 in various directions, including the generally vertical, generally horizontal, and radial/circumferential directions.
As shown in
Lids 200 are configured to nest together and interlock with one another as shown in
As shown in
Different arrangements of the components depicted in the drawings or described above, as well as components and steps not shown or described are possible. Similarly, some features and subcombinations are useful and may be employed without reference to other features and subcombinations. Embodiments of the invention have been described for illustrative and not restrictive purposes, and alternative embodiments will become apparent to readers of this patent. Accordingly, the present invention is not limited to the embodiments described above or depicted in the drawings, and various embodiments and modifications can be made without departing from the scope of the claims below.
As used below, any reference to a series of examples is to be understood as a reference to each of those examples disjunctively (e.g., “Examples 1-4” is to be understood as “Examples 1, 2, 3, or 4”).
Example 1 is a curvilinear metal transfer device comprising an outer casing comprising a curvilinear inner wall and a curvilinear outer wall, wherein the outer casing includes individual sections that are joined together at casing joints by a plurality of compression assemblies; and an inner refractory positioned within the outer casing and comprising a curvilinear inner wall and a curvilinear outer wall, wherein the inner refractory includes sections that abut one another at refractory joints, and wherein the compression assemblies are configured to account for lesser expansion of the curvilinear inner wall of the inner refractory than the curvilinear outer wall of the inner refractory.
Example 2 is the curvilinear metal transfer device of example 1, wherein each of the casing joints comprises a first side proximate the curvilinear inner wall of the inner refractory and a second side proximate the curvilinear outer wall of the inner refractory, and wherein the first side and the second side each comprise a stationary flange attached to the outer casing and a compression flange that is movable relative to the stationary flange.
Example 3 is the curvilinear metal transfer device of example 2, wherein the compression flanges are compressible via the plurality of compression assemblies in a circumferential direction to reduce gaps between the sections.
Example 4 is the curvilinear metal transfer device of examples 1-3, wherein each of the plurality of compression assemblies includes a fastener, a locking nut, and one or more spring washers that allow limited movement of the compression flanges.
Example 5 is the curvilinear metal transfer device of examples 1-4 further comprising a plurality of clamp plates arranged along and compressibly fastened to a top of the outer casing, wherein each of the plurality of clamp plates is operably engaged with an upper portion of the inner refractory to help maintain an alignment of the inner refractory.
Example 6 is the curvilinear metal transfer device of example 5, wherein each of the plurality of clamp plates includes a locator pin receivable within a groove of the upper portion of the inner refractory.
Example 7 is the curvilinear metal transfer device of examples 5 or 6, wherein each of the plurality of clamp plates includes a fastener and one or more spring washers to allow for a limited amount of vertical movement between the clamp plate and the inner refractory.
Example 8 is the curvilinear metal transfer device of example 1-7, wherein the inner refractory is supported within the outer casing by a plurality of compressible support assemblies, each of the plurality of compressible support assemblies comprising a push rod having a proximal end and an opposed distal end that is configured to bear against the inner refractory, the push rod made of a heat-insulating material; a cap with a shoulder surface and a distal sleeve extending from the shoulder surface that fits over the proximal end of the push rod, wherein a wall of the distal sleeve extends for a length smaller than a length of the push rod; a plate configured to mount to the outer casing and defining an aperture through which the push rod extends; a fastener attached to the plate proximal of the push rod, the fastener having a distal abutment surface; and at least one spring washer mounted on the cap and configured to engage the shoulder surface of the cap and the distal abutment surface of the fastener so as to bias the push rod against the inner refractory.
Example 9 is the curvilinear metal transfer device of examples 1-8, further comprising a plurality of lids for covering the inner refractory, wherein each of the plurality of lids includes a first end and a second end, wherein the first end comprises a cavity and the second end comprises a protrusion receivable within the cavity, wherein the plurality of lids nest together in an arrangement such that the protrusion of the second end of one of the plurality of lids interlocks with the cavity of the first end of another one of the plurality of lids, and wherein the arrangement allows one of the plurality of lids to be removed without requiring that all of the plurality of lids be removed.
Example 10 is a curvilinear metal transfer device comprising an outer casing comprising a curvilinear inner wall and a curvilinear outer wall; and an inner refractory positioned within the outer casing and comprising a curvilinear inner wall and a curvilinear outer wall, wherein a plurality of lids are configured to nest together to generally cover a top of the curvilinear metal transfer device.
Example 11 is the curvilinear metal transfer device of example 10, wherein each of the plurality of lids is dimensioned to correspond to dimensions of a section of the inner refractory.
Example 12 is the curvilinear metal transfer device of examples 10 or 11, wherein each of the plurality of lids includes a first end and a second end, wherein the first end comprises a cavity and the second end comprises a protrusion receivable within the cavity.
Example 13 is the curvilinear metal transfer device of examples 10-12, further comprising a clamp to help keep one or more of the plurality of lids in position.
Example 14 is the curvilinear metal transfer device of example 10-13, wherein the plurality of lids nest together in an arrangement such that a protrusion of a second end of one of the plurality of lids interlocks with a cavity of a first end of another one of the plurality of lids, wherein the arrangement allows one of the plurality of lids to be removed without requiring that all of the plurality of lids be removed.
Example 15 is the curvilinear metal transfer device of examples 10-14, wherein individual sections of the outer casting are joined together at casing joints by a plurality of compression assemblies, wherein individual sections of the refractory abut one another at refractory joints, and wherein the compression assemblies are configured to account for lesser expansion of the curvilinear inner wall of the inner refractory than the curvilinear outer wall of the inner refractory.
Example 16 is a curvilinear metal transfer device comprising an outer casing comprising a curvilinear inner wall and a curvilinear outer wall, wherein the outer casing includes individual sections that are joined together at casing joints; an inner refractory positioned within the outer casing and comprising a curvilinear inner wall and a curvilinear outer wall, wherein the inner refractory includes sections that abut one another at refractory joints, wherein the inner refractory is supported within the outer casing by a plurality of compressible support assemblies, each of the plurality of compressible support assemblies comprising: a push rod having a proximal end and an opposed distal end that is configured to bear against the inner refractory, the push rod made of a heat-insulating material; a plate configured to mount to the outer casing and defining an aperture through which the push rod extends; a fastener attached to the plate proximal of the push rod, the fastener having a distal abutment surface; and at least one spring washer positioned between the push rod and the fastener so as to bias the push rod against the inner refractory.
Example 17 is the curvilinear metal transfer device of example 16, wherein each of the plurality of compressible support assemblies further comprises a cap with a shoulder surface and a distal sleeve extending from the shoulder surface that fits over the proximal end of the push rod, wherein a wall of the distal sleeve extends for a length smaller than a length of the push rod, and wherein the at least one spring washer is mounted on the cap to engage the shoulder surface of the cap and the distal abutment surface of the fastener.
Example 18 is the curvilinear metal transfer device of example 17, wherein the fastener comprises an axially aligned sleeve shaped to receive an extension of the cap.
Example 19 is the curvilinear metal transfer device of examples 16-18, wherein the fastener is configured to compress the at least one spring washer and press the push rod into contact with the inner refractory.
Example 20 is the curvilinear metal transfer device of examples 16-19, wherein the individual sections of the outer casing are joined together at the casing joints by a plurality of compression assemblies, and wherein the compression assemblies are configured to account for lesser expansion of the curvilinear inner wall of the inner refractory than the curvilinear outer wall of the inner refractory.
The present application claims the benefit of U.S. Provisional Application No. 62/040,694 filed on Aug. 22, 2014 and entitled “SUPPORT AND COMPRESSION ASSEMBLIES FOR CURVILINEAR MOLTEN METAL TRANSFER DEVICE,” which is hereby incorporated by reference in its entirety.
Number | Date | Country | |
---|---|---|---|
62040694 | Aug 2014 | US |