Molten metal filter

Abstract

According to another embodiment, a molten metal filter is provided having two opposing plates. At least one hollow elongated member comprising a porous refractory material is attached at a first end to a first end plate and at a second end to a second end plate. The first end plate has a passageway extending through a width of the first end plate and a ledge for receiving the first end of the elongated member. The second end plate has an opening for receiving the second end of the elongated member. The opening extends through the width of the second end plate and has a dimension greater than the circumference of the elongated member.

Description

Technical Field

[0004]

[0001] This application claims the priority of U.S. Provisional Application No. 63 / 162,896, filed on March 18, 2021, the disclosure of which is incorporated herein by reference. This exemplary embodiment relates to a filter. In particular, it can be used for the use of a cartridge filter for removing solid inclusions from molten metal, and will be described specifically with reference thereto. However, it should be understood that this exemplary embodiment is also applicable to other similar uses.

Background Art

[0002] Molten aluminum generally contains solid inclusions that are harmful to the final cast metal product. These solid inclusions usually originate from three sources. Some are oxide particles drawn into the liquid stream from the oxide layer floating on the surface, and some intervening particles are fragments of the furnace lining, transfer trough, and other parts of the molten aluminum processing equipment, which are corroded and drawn into the flowing aluminum stream, and some particles are precipitates of insoluble impurities such as precipitates of intermetallic compounds, borides, carbides, or other aluminum compounds such as aluminum chloride.

[0003] When inclusions appear in the final cast product after the molten aluminum has solidified, such final products have reduced ductility, reduced strength, or poor finishing characteristics. Therefore, it is desirable to remove solid inclusions from molten aluminum before casting it into a solid body that may be used as is or may be subjected to shaping operations such as rolling, forging, extrusion, etc.

[0004] The cartridge filtration process removes solid inclusions from a liquid by passing the liquid containing solids through a porous, homogeneous filter medium on which a cake forms. Cake formation can be promoted by introducing a cake-forming additive, such as excess titanium diboride, into the molten metal. Cake formation can be controlled to adjust the filtration process. Typically, the filtration process terminates when the cake is released.

[0005] In general, filtering molten metals, especially molten aluminum, presents a particular problem: because the liquid is highly aggressive, it is difficult to find filter media that can withstand its aggressive chemical and thermal environment. In such systems, heat-resistant material filter media or filter elements are used. Preferred materials resist melting at high temperatures, chemical reactions with the metal, and degradation by erosion. The filter media must also maintain structural integrity at such high temperatures and, of course, capture or block the flow of solids and semi-liquids by preventing chemical reactions and / or mechanically preventing their flow through it.

[0006] Various means for achieving filtration are known to those skilled in the art. Examples of these are found in U.S. Patent Nos. 4,964,993; 4,444,377; 4,426,287; 4,413,813; 4,384,888; 4,330,328; 4,330,327; 4,302,502; 4,298,187; 4,258,099; 4,179,102; 4,159,104; 4,081371; 4,032,124; 3,869,282; and 5,126,047, which are incorporated herein by reference. U.S. Patent No. 5,369,063, incorporated herein by reference, discloses a foam filter made of alumina that can be formed into a plate. In the art, cartridge filters comprising multiple rectangular end plates interconnected by filter tubes are also used (see, for example, U.S. Patents No. 3,747,765 and 5,741,422, whose disclosures are incorporated herein by reference). [Prior art documents] [Patent Documents]

[0007] [Patent Document 1] U.S. Patent No. 4,964,993 [Patent Document 2] U.S. Patent No. 4,444,377 [Patent Document 3] U.S. Patent No. 4,426,287 [Patent Document 4] U.S. Patent No. 4,413,813 [Patent Document 5] U.S. Patent No. 4,384,888 [Patent Document 6] U.S. Patent No. 4,330,328 [Patent Document 7] U.S. Patent No. 4,330,327 [Patent Document 8] U.S. Patent No. 4,302,502 [Patent Document 9] U.S. Patent No. 4,298,187 [Patent Document 10] U.S. Patent No. 4,258,099 [Patent Document 11] U.S. Patent No. 4,179,102 [Patent Document 12] U.S. Patent No. 4,159,104 [Patent Document 13] U.S. Patent No. 4,081,371 [Patent Document 14] U.S. Patent No. 4,032,124 [Patent Document 15] U.S. Patent No. 3,869,282 [Patent Document 16] U.S. Patent No. 5,126,047 [Patent Document 17] U.S. Patent No. 5,369,063 [Patent Document 18] U.S. Patent No. 3,747,765 [Patent Document 19] U.S. Patent No. 5,741,422 [Overview of the project] [Problems that the invention aims to solve]

[0008] Cartridge filters are often considered superior filters due to their excellent throughput, filtration capacity, and lifespan. One problem inherent in conventional cartridge filter designs is that the end plates at the outlet end of the filter box tend to crack, allowing bypass of unfiltered molten metal. This disclosure provides a cartridge filter with a high degree of structural integrity and excellent filtration characteristics. [Means for solving the problem]

[0009] The following is a summary of various details of this disclosure to provide a basic understanding. This summary is not a comprehensive overview of the disclosure and is not intended to identify specific elements of the disclosure or to clarify its scope. Rather, the main purpose of this summary is to present a simplified concept of the disclosure before the more detailed explanations provided below.

[0010] According to the first embodiment, a molten metal filter is provided comprising two opposing plates and at least one hollow elongated member. The elongated member is formed from a porous refractory material and is attached at a first end to a first end plate and at a second end to a second end plate. The first end plate extends through the width of the end plate and has a passage for receiving the first end of the elongated member. The second end plate has an opening for receiving the second end of the elongated member. The opening of the second end plate includes an element configured to accommodate the thermal expansion of the elongated member.

[0011] According to another embodiment, a molten metal filter having two opposing plates is provided. At least one hollow elongated member, comprising a porous refractory material, is attached to a first plate at a first end and to a second plate at a second end. The first plate has a passage extending through the width of the plate and a ledge in the passage that receives the first end of the elongated member. The second plate has an opening that receives the second end of the elongated member. The opening passes through the width of the second plate and has dimensions greater than the circumference of the elongated member.

[0012] According to a further embodiment, a molten metal filter is provided that includes two opposing plates and at least one hollow elongate member extending therebetween. The elongate member and at least the first plate include a porous refractory material. The porous refractory material plate has an opening that receives one end of the elongate member. This opening extends through the width of this plate. At least a portion of the surface of this plate facing the elongate member includes a cement coating.

[0013] According to another embodiment, a method for filtering molten metal is provided. This method includes providing a cartridge filter having two opposing plates and at least one hollow elongate member. The elongate member and at least the first plate include a porous refractory material. The first plate has an opening that receives one end of the elongate member. This opening extends through the width of this plate. At least a portion of the surface of the first plate facing the elongate member includes a cement coating. The cartridge filter is disposed within a filter box having an inlet side and an outlet side. Molten metal is introduced into the inlet side of the filter box such that the molten metal reaches the outlet through the porous refractory material of a portion of the first plate that does not include the elongate member and the cement coating.

Brief Description of the Drawings

[0014] The following presents a brief description of the drawings, which are presented for the purpose of illustrating exemplary embodiments disclosed herein and are not intended to be limiting.

[0015] The present invention consists of novel parts, configurations, arrangements, combinations, and improvements shown and described. The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate an embodiment of the invention and together with the specification serve to explain the principles of the invention.

[0016] [Figure 1]This is a cross-sectional view of a conventional molten metal cartridge filter assembly.

[0017] [Figure 2] This is a perspective view of the end plate of the cartridge filter of this disclosure.

[0018] [Figure 3] This is a cross-sectional view of an individual tube as a component of a cartridge filter assembly configured in accordance with this disclosure.

[0019] [Figure 4] This is a cross-sectional view of a passage in the end plate of a molten metal cartridge filter configured according to another embodiment of the present disclosure.

[0020] [Figure 5] This is a cross-sectional view of a passage in the end plate of a molten metal cartridge filter configured according to yet another embodiment of the present disclosure.

[0021] [Figure 6] This is a cross-sectional view of a filter box according to a further embodiment of the present disclosure. [Modes for carrying out the invention]

[0022] A more complete understanding of the components, processes, and apparatus disclosed herein can be obtained by referring to the accompanying drawings. These drawings are merely schematic diagrams based on convenience and ease of illustrating the present disclosure and are therefore not intended to show the relative sizes and dimensions of the apparatus or its components, and / or to define or limit the scope of exemplary embodiments.

[0023] In the following description, certain terms are used for clarity, but these terms are intended to refer only to specific structures of embodiments selected for illustration in the drawings and are not intended to define or limit the scope of the disclosure. In the following drawings and description, numerical symbols should be understood to refer to components having a function, etc.

[0024] The singular forms "a," "an," and "the" include the plural form unless otherwise specified.

[0025] In its use herein, the term “about” is intended to encompass structural or numerical changes that, in general and substantial terms, do not significantly affect the purpose of the element or number modified by such term.

[0026] In use in the specification and claims, the term “comprising” may include embodiments of “consisting of” and “consisting essentially of.” In this use, the terms “comprise(s),” “include(s),” “having,” “has,” “can,” “contain(s),” and their variations are intended to be open-ended transitional phrases, terms, or words that require the presence of a specified component / step and permit the presence of other components / steps. However, such descriptions should also be interpreted as describing a composition or process as “consisting of” and “consisting essentially of” the listed components / steps, which permit the presence of only the specified component / step and any impurities that may arise therefrom, and exclude other components / steps.

[0027] Referring to Figure 1, a prior art molten metal cartridge filter is indicated by reference numeral 2. It comprises four horizontally arranged cylindrical tubes 4 (only two of which are shown), which are connected at their ends to a pair of parallel plates 6, 8. Plate 6 includes an opening 10 that communicates with the hollow open ends of the tubes 4. Plate 8 includes four recesses 9 that receive the closed ends of the hollow tubes 4. A heating element 11 can be provided inside the lid of the filter box 12.

[0028] A filter 2 is placed inside the filter box 12. When molten metal enters the filter box 12 through the inlet 14, it is forced through the tube wall into the hollow tube interior 21 and through the opening 10 to reach the outlet 16. The molten metal is filtered as it passes through the cake that forms on the surface of each hollow tube.

[0029] The passage 10 extends from the inner surface 23 to the outer surface 25 of plate 6. Each passage 10 has a ledge 27 formed to receive the end of the pipe 4. Plate 8 includes a recess 29 to receive the opposite end of the pipe 4. Because plate 6 has less material than plate 8 (passage vs. recess), it has been found that thermal expansion of the pipe is prone to cracking in plate 6, even when a gasket is used. Cracks in plate 6 allow for the undesirable flow of unfiltered metal from the filter box 12 to the outlet 16 and the downstream casting operation.

[0030] Referring here to Figure 2, cartridge plate 106 is shown adjacent to cartridge plate 108. Cartridge plate 106 is intended to be installed on the outlet side of the filter box, and cartridge plate 108 is intended to be installed on the inlet side of the filter box. In the assembled state, the filter tube extends between plates 106 / 108. These plates can be made of, for example, graphite, silicon carbide, or ceramic silicate, and the tube can be made of, for example, glass, silicon carbide, or alumina bound particles.

[0031] The first closed end of the tube is received in the opening 110, and the second open end of the tube is received in the passage 112. The passage 112 passes through the width of the cartridge plate 106 but includes a ledge 113 that abuts against the end of the tube. The opening 110 passes through the width of the plate 108. The opening 110 may be large enough to accommodate the entire circumference of the tube over the length of the opening. The opening 110 is provided to allow thermal expansion of the tube in the longitudinal direction within the opening. In this regard, although the opening 110 is shown to penetrate the entire width of the end plate, it is assumed that the opening is only deep enough to accommodate the thermal expansion (see Figure 3). However, it should be noted that an opening that penetrates the entire plate may be advantageous in that the end walls of the filter tube become an additional filtration surface. The end plate 108 may be further modified to include elements that allow for the assembly of the cartridge filter for transport and installation.

[0032] Referring here to Figure 3, one design for configuring, transporting, installing, and enabling thermal expansion of a cartridge filter is shown. In particular, the filter tube 200 is inserted only partially into the recess 202, leaving an expansion gap 204. The elongated tube 200 is secured to the end plate 208 using a cement fillet 210. The opposite end of the elongated tube 200 is secured with cement to a passage within the end plate 212. The amount of cement is chosen to provide sufficient structural integrity for the assembled cartridge filter to enable transport and installation, while also providing preferential failure at the fillet when thermal expansion occurs.

[0033] In this regard, the amount of cement used should form a joint with less structural integrity than the end plate 106. Furthermore, the fillet 210 is minimal so that when the length of the long pipe 206 is expanded, the fillet cracks and the end of the pipe expands into the expansion gap 204 rather than cracking either end plate. Here, the cement fillet can be thin, discontinuous, or both, along the entire circumference of the pipe.

[0034] Here, with reference to Figure 4, another embodiment is shown. In this embodiment, the inlet end plate 308 includes an opening 310 (only one is shown) that runs through the entire width of the end plate. The dimensions of the opening 310 will be large enough to facilitate the insertion of the closed end of the filter tube 311. The opening further comprises at least one tab 312. The tab 312 may be a single body of cement. The cement may be applied as a coating to one or both of the surfaces of the opening 310 or the tube 311. When the tube is inserted into the opening, the cement can flow into the recess 316 in the tube and into the recess 318 in the end plate, forming the tab 312 after hardening.

[0035] Alternatively or additionally, grooves 320 (or more grooves) can be provided to allow cement injection into the recess 318. The recess can be of any shape (e.g., circular or rectangular). Similarly, it should be noted that the recess can be continuous or discontinuous over the entire circumference of the interface between the pipe and the end plate.

[0036] Here, with reference to Figure 5, yet another embodiment is shown. In this embodiment, the filter tube 411 is also inserted into a passage 410 formed in the end plate 408. A tab 412 receives the end portion 414 of the closed end of the filter tube 411. The interface between the filter tube 411 and the tab 412 can be fixed with cement. When thermal expansion occurs in the filter tube 411 and it expands further into the passage 410, the tab 412 breaks or detaches, allowing the end portion 414 to expand deeper into the passage. In some embodiments, the expansion may be sufficient for the end portion 414 of the filter tube 411 to contact a second tab 418.

[0037] In any of the embodiments described above, the tab may be constructed of a size, material, and / or design that breaks during the thermal expansion of the tube, allowing the tube to further penetrate into the opening without cracking the end plate. For example, tab 412 may have a thickness (indicated as 5 mm) that it preferentially breaks. Alternatively, tab 412 may be receptive within a minimum detent 416 to allow the tab to detach from the end plate during the thermal expansion of the filter tube. As a further alternative, the tab may be constructed of a material that melts into a molten metal such as aluminum or magnesium.

[0038] The filter tubes can be circular in cross-section, but the cross-sectional configuration is not critical, and other shapes can be selected as needed. However, it would be advantageous if the end plate recesses were at least of a similar general shape. A compressible aluminum-compatible sealant material, such as a fiberflux gasket (manufactured by Pyrotec), which is an alumina-silica fiber sheet material useful at temperatures above 2,000°F, can be interposed between the plate surface and each tube.

[0039] Referring here to the embodiment in Figure 6, a cartridge filter 502 is provided in which a cylindrical tube 504 extends between two opposing end plates 506, 508. The cylindrical tube and at least the end plates 506 may be made of a porous refractory material.

[0040] In one embodiment, the entire inner surface of the end plate 506 (e.g., areas 510, 512, and 515) is coated with at least substantially refractory cement. Furthermore, the inner surface of the end plate 506 that is not obstructed by the pipe 504 may also include this coating.

[0041] Advantageously, the cement-coated bonded particle plates of this disclosure have been found to be less expensive and stronger than conventional plates formed from castable silicon carbide or castable alumina silicon carbide. In this way, an inexpensive end plate that is less prone to cracking due to thermal expansion is provided.

[0042] Alternatively, a portion of the surface of the end plate 506 facing the pipe may include a cement coating, while a portion suitable for filtering the molten metal to pass toward the outlet 516 may not include a cement coating. For example, regions 510 and 512 may include a cement coating, while region 515 may not include one. This design allows the molten metal to flow through region 515 of the end plate 506 to the outlet 516.

[0043] Furthermore, the cement-coated areas are configured to prevent molten metal from entering the binding particle material, while the uncoated areas increase the surface area available for filtration, improving the efficiency of the cartridge filter. The coated areas prevent the flow of molten metal to undesirable areas of the filter box and provide a significant increase in strength to resist thermal expansion cracks in the end plates.

[0044] In a feasible configuration, the inner surface and optionally the outer surface of the end plate 506 would be coated at any position not aligned with the opening 518 to the exit 516. The plate 508 can be coated on its inner surface and optionally its outer surface.

[0045] An exemplary cement coating would have a thickness of approximately 1–5 mm. The exemplary cement would be one with high heat resistance and low CTE, such as a sodium silicate / clay or alumina-silica / clay type. A suitable cement could be Frakset® cement, available from Pyrotec.

[0046] Plate 506 (optionally plate 508) and the pipe are, Glass bonding particles, silicon carbide bonding particles,Alternatively, it can be composed of bonded aluminum oxide particles. The particles can be bonded using binders such as CaO-Al2O3-B2O3 and MgO-Al2O3-B2O3.

[0047] The particles forming the plate may have a particle size smaller than or equal to the particles forming the long tube. In this way, the molten metal will pass through the tube at a speed equal to or higher than that of the end plate 506.

[0048] According to the embodiment in Figure 6, the molten metal filtration method allows the molten metal to be introduced into the inlet side 514 of the filter box so that it passes through the porous refractory material of the elongated member 504 and the porous refractory material region 515 (if not coated) of the first plate 506 to the outlet.

[0049] The exemplary embodiments have been described with reference to preferred embodiments. Obviously, modifications and changes will also occur to others as read and understood in the preceding detailed description. The exemplary embodiments are intended to be construed to include all such modifications and changes, insofar as they fall within the scope of the appended claims or their equivalents.

[0050] To help readers of this application and the resulting patents interpret the claims attached herein, the applicant does not intend that the attached claims or elements of the claims invoke 35 U.S.C. 112(f) unless the terms “means for” or “step for” are expressly used in any particular claim.

Claims

1. Two opposing plates, It includes a porous fire-resistant material and at least one hollow elongated member attached to a first end plate at a first end and to a second end plate at a second end, The first end plate has a passage that extends through the width of the first end plate and receives the first end of the elongated member, The second end plate has an opening that penetrates the second end plate in the width direction and receives the second end of the elongated member, and the second end plate includes an element configured to accommodate the thermal expansion of the elongated member. The element includes a tab positioned within the opening, The tab is formed to fill a ring-shaped recess that is continuously or discontinuously formed on the inner circumferential surface of the opening and to protrude inward from the inner circumferential surface. The tab is susceptible to damage due to thermal expansion of the elongated member. Molten metal filter.

2. Two opposing plates, It includes a porous fire-resistant material and at least one hollow elongated member attached to a first end plate at a first end and to a second end plate at a second end, The first end plate has a passage that extends through the width of the first end plate and receives the first end of the elongated member, The second end plate has an opening that penetrates the second end plate in the width direction and receives the second end of the elongated member, and the second end plate includes an element configured to accommodate the thermal expansion of the elongated member. The element includes a cement fillet positioned within or adjacent to the opening. Molten metal filter.

3. The second end of the long member is closed. The filter according to claim 1 or 2.

4. The molten metal filter according to claim 1 or 2 is provided, wherein the first end plate comprises a porous refractory material and is disposed within a filter box having an inlet side and an outlet side. The molten metal is introduced into the inlet side of the filter box so that it passes through the porous refractory material of the elongated member and a portion of the porous refractory material of the first end plate without cement coating, and reaches the outlet. A method for filtering molten metal.

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