Molten metal filtering device for casting vehicle parts

Abstract

A molten aluminum metal filtration system has a storage tank operable to receive molten metal, a filtration device for filtering the molten metal, a pump operable to continuously recycle the molten metal through the filtration device, and a casting device for receiving filtered molten metal from the filtration device. The filtration device includes a chamber, an inlet channel operable to deliver molten metal into the chamber, and an outlet channel operable to deliver unused filtered molten metal out of the chamber and back to a storage tank. And the detachable filtering element is arranged in the inlet channel in series. The removable filter element is used to filter inclusions exceeding a determined diameter dimension from the molten metal. The filter device includes at least one nozzle operable to direct an inert gas flow to cover the molten metal and a heating element.

Description

Technical Field

[0001] The present disclosure relates to casting of vehicle parts, and more particularly to a molten metal alloy filtering device for casting vehicle parts. Background Art

[0002] Casting is a process characterized by injecting a molten metal alloy into a mold cavity having a predetermined shape of the desired cast component. High pressure die casting (HPDC) and low pressure die casting (LPDC) processes are commonly used in the automotive industry for casting vehicle components, especially vehicle components in very large cast components. Very large cast components, also known as super-large castings, make vehicles lighter and less complex to manufacture by replacing a large number of stamped panels with a single very large casting. Due to the huge size of the die casting machines used to make these castings, these very large castings are often referred to as giant castings or giga castings. As a non-limiting example, a single very large casting may be not less than 0.8 meters in width, not less than 1 meter in length, and not less than 0.25 meters in height.

[0003] In the automotive industry, molten cast aluminum alloys are often subjected to a spin degassing process before being injected into the die casting mold. The spin degassing process injects inert gases such as nitrogen or argon into the molten metal cast aluminum alloy through a rotating graphite rod, thereby reducing contaminants such as hydrogen and aluminum oxide that cause porosity and other inclusions in the solidified casting.

[0004] Therefore, while spin degassing of molten cast alloys achieves its intended purpose, there is still a need to further improve the quality of the molten alloy to eliminate unwanted contaminants before introducing the molten alloy into the casting mold when manufacturing very large cast vehicle components. Summary of the invention

[0005] According to several aspects, a molten metal filtering device is disclosed. The molten metal filtering device includes a housing and a first filter element, the housing having an inner surface defining an inlet channel, an outlet channel, and a chamber in fluid communication with the inlet channel and the outlet channel, and the first filter element is disposed in the inlet channel. The inlet channel is used to transport the molten metal into the chamber, and the outlet channel is used to guide the molten metal out of the chamber. The first filter element includes a shape factor occupying a cross-section of the inlet channel, and the inlet channel is perpendicular to the flow direction of the molten metal flowing through the inlet channel. The first filter element is operable to filter the molten metal to produce filtered molten metal.

[0006] In another aspect of the present disclosure, the chamber may enable transfer of a portion of the filtered molten metal from the chamber to a casting apparatus.

[0007] In another aspect of the present disclosure, the molten metal filtering apparatus further includes a nozzle operable to direct an inert gas to flow into at least one of the inlet channel and the outlet channel to cover the molten metal.

[0008] In another aspect of the present disclosure, a second filter element is disposed in the inlet passage downstream of the first filter element.

[0009] In another aspect of the present disclosure, the outlet channel is adjacent to the inlet channel and the two are separated by a heat conductive partition wall.

[0010] In another aspect of the present disclosure, the outlet passage is used to convey the molten metal in a direction opposite to the flow direction of the molten metal flowing through the inlet passage.

[0011] In another aspect of the present disclosure, the molten metal filtration apparatus further includes at least one pump in fluid communication with at least one of the inlet channel and the outlet channel.

[0012] In another aspect of the present disclosure, at least one pump includes an upstream pump in fluid communication with the reservoir and the inlet channel and a downstream pump in fluid communication with the outlet channel and the reservoir. The upstream pump is operable to draw molten metal from the reservoir and push the molten metal through the inlet channel. The downstream pump is operable to draw molten metal from the outlet channel and push the molten metal to the reservoir.

[0013] In another aspect of the present disclosure, the molten metal filtering device further comprises a cover covering at least one of the inlet channel and the outlet channel, wherein the cover comprises a detachable opening so that the first filter element can be selectively removed.

[0014] In another aspect of the present disclosure, the molten metal filtering apparatus further includes a heating element disposed within the housing and located above at least one of the inlet channel and the outlet channel.

[0015] According to several aspects, a molten metal filtration system is disclosed. The system includes: a storage tank operable to receive molten metal; a filtration device including a chamber, an inlet channel operable to receive molten metal from the storage tank and deliver the molten metal to the chamber, and an outlet channel operable to deliver the molten metal out of the chamber and back to the storage tank; a pump operable to move the molten metal from the storage tank through the inlet channel; and a plurality of removable filters arranged in series in the inlet channel. The plurality of removable filters are operable to remove inclusions in the molten metal that exceed a certain diameter size.

[0016] In another aspect of the present disclosure, the outlet channel is in thermal communication with the inlet channel. The flow direction of the molten metal flowing through the outlet channel is opposite to the flow direction of the molten metal flowing through the inlet channel.

[0017] In another aspect of the present disclosure, at least one of the plurality of removable filters includes at least one of zirconium silicate, zirconium oxide, and silicon carbide and has a pore size sufficient to remove particles having a size of about 20 microns and greater.

[0018] In another aspect of the present disclosure, the filtering device includes at least one nozzle operable to direct an inert gas flow into at least one of the inlet channel and the outlet channel to cover the molten metal.

[0019] In another aspect of the present disclosure, the chamber may enable transfer of filtered molten metal from the chamber to a casting apparatus.

[0020] According to several aspects, a continuous flow molten metal filtration system is closed. The system includes a filtration device operable to filter a molten casting alloy to produce a filtered molten casting alloy and a casting device operable to receive the filtered molten casting alloy to form a solidified casting. The filtration device includes an inlet channel, a chamber located downstream of the inlet channel, an outlet channel located downstream of the chamber, and at least one removable filter disposed in the inlet channel.

[0021] In another aspect of the present disclosure, the system further includes a pump operable to continuously recirculate the molten metal through the inlet passage, the chamber, and the outlet passage.

[0022] In another aspect of the present disclosure, the inlet channel is in thermal communication with the outlet channel. The flow direction of the molten cast alloy in the outlet channel is opposite to the flow direction of the molten cast alloy in the inlet channel.

[0023] According to another aspect of the present disclosure, the filtering device includes at least one nozzle operable to direct an inert gas into at least one of the inlet passage and the outlet passage to cover the molten cast alloy.

[0024] In another aspect of the present disclosure, the chamber may enable transfer of filtered molten metal from the chamber to a casting apparatus.

[0025] Further areas of applicability will become apparent from the description provided herein.It should be understood that the description and specific examples are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The drawings described herein are for illustration purposes only and are not intended to limit the scope of the present disclosure in any way.

[0027] Figure 1 is a schematic diagram of a casting system having a continuous recirculation filtration device;

[0028] Figure 2A is a schematic cross-sectional plan view of a filtering device;

[0029] Figure 2B is a schematic cross-sectional elevation view of a filtration device;

[0030] Figure 3 is a schematic diagram of a casting apparatus; and

[0031] Figure 4 is an illustration of a typical oversized casting of a vehicle body component. DETAILED DESCRIPTION

[0032] The following description is merely exemplary in nature and is not intended to limit the present disclosure, application, or use. The illustrated embodiments are disclosed in conjunction with the accompanying drawings, wherein the same reference numerals in the drawings represent corresponding parts. The drawings are not necessarily drawn to scale, and certain features may be enlarged or minimized to show details of particular features. Therefore, the specific structural and functional details disclosed herein should not be interpreted as limiting, but only as a representative basis to teach those skilled in the art how to practice the disclosed concepts.

[0033] Figure 1 1 is a schematic diagram of a die casting system 100 having a filtration device 200 for continuously recycling molten metal alloy. The die casting system 100 includes a storage tank 102, a molten metal alloy filtration device 200, and a die casting device 300. For the sake of brevity, the die casting system 100 is also referred to as system 100, the storage tank 102 is also referred to as a reservoir 102, and the molten metal alloy filtration device 200 is also referred to as a filtration device 200. The system 100 also includes at least one delivery pump 104A, 104B, which is operable to continuously recirculate the molten metal alloy through the filtration device 200. The molten metal alloy is also referred to as molten metal or molten alloy. A first portion 105A of the filtered molten alloy obtained after filtering by the filtration device 200 is fed into the die casting device 300, and the remaining second portion 105B of the filtered molten alloy obtained after filtering by the filtration device 200 is fed into the reservoir 102 to be recycled through the filtration device 200.

[0034] In the non-limiting example shown, the reservoir 102 is used to receive an unfiltered molten alloy 103 from a molten alloy source (not shown) and a second portion 105B of the filtered molten alloy obtained after filtering by the filtering device 200. The mixture of the unfiltered molten alloy 103 and the filtered molten alloy 105B is referred to as the partially filtered molten alloy 107. In one embodiment, the at least one delivery pump 104A, 104B includes only an upstream delivery pump 104A, also referred to as a first pump 104A, which is operable to draw the partially filtered molten alloy 107 from the reservoir 102 and push the partially filtered molten alloy 107 through the filtering device 200. In another embodiment, the at least one delivery pump 104A, 104B includes only a downstream delivery pump 104B, also referred to as a second pump 104B, which is operable to draw the second portion 105B of the filtered molten alloy from the filtering device 200 and push the second portion 105B of the filtered molten alloy to the reservoir 102 for recirculation through the filtering device 200. In yet another embodiment, at least one delivery pump 104A, 104B includes an upstream pump 104A and a downstream pump 104B. The upstream pump 104A cooperates with the downstream pump 104B to provide a consistent predetermined flow rate through the filter device 200 by balancing the flow rate of the partially filtered molten alloy 107 entering the filter device 200 with the flow rate of the second portion 105B of the filtered molten alloy flowing out of the filter device 200.

[0035] Figure 2A 2 is a schematic cross-sectional plan view of the filter device 200. The filter device 200 includes a housing 202 having an inner surface 204 defining an inlet channel 206, an outlet channel 208, and a chamber 210 in fluid communication with the inlet channel 206 and the outlet channel 208. The inlet channel 206 includes an inlet 212 for receiving a flow of molten metal from the reservoir 102. The outlet channel 208 includes an outlet 214 in fluid communication with the reservoir 102. The molten metal flows from the reservoir 102 through the inlet channel 206 and into the chamber 210. The molten metal flows from the chamber 210 through the outlet channel 208 and returns to the reservoir 102, or is transported from the chamber 210 to the die casting device 300.

[0036] A plurality of removable filter elements, such as a first filter element 218A and a second filter element 218B, are arranged in series within the inlet channel 206 to filter the molten alloy flowing through the inlet channel 206 to the chamber 210. The first filter element 218A and the second filter element 218B have a shape factor for filling the cross-sectional area (A) of the inlet channel 206, which is perpendicular to the direction of the molten alloy flow in the inlet channel 206. The inner surface 204 of the housing 202 may also define a groove 219 to accommodate the filter elements 218A, 218B. The filter elements 218A, 218B may be made of, including but not limited to, zirconium silicate, zirconium oxide, silicon carbide, and other materials that can withstand the temperature and flow of the molten alloy and filter out contaminants above a predetermined diameter size.

[0037] For aluminum-silicon (Al-Si) casting alloys, filter elements 218A, 218B are required to have an aperture of about 20 microns in diameter, so as to remove unnecessary pollutants, such as slag, foam and oxides, whose diameter is greater than 20 microns in the molten alloy flow. These pollutants can produce pores and other unnecessary inclusions in the solidified casting. Another benefit is that filter elements 218A, 218B are convenient for homogenizing the alloy elements in the molten metal, and when the molten metal flows through the filter device 200, turbulent flow is converted into laminar flow by slowing down the molten metal flow. This causes the pollutant size entering the die casting device 300 to be significantly smaller. The holes of filter elements 218A, 218B can have a predetermined shape to extend the service life of filter elements 218A, 218B and not blockage. Filter elements 218A, 218B can be made by additive manufacturing methods such as three-dimensional (3-D) printing.

[0038] In the non-limiting example shown, the inlet channel 206 is adjacent to the outlet channel 208 and is separated from the outlet channel 208 by a heat-conducting partition wall 216. The inlet channel 206 is thermally connected to the outlet channel 208, which means that heat energy is transferred between the molten metal flowing through the inlet channel 206 and the outlet channel 208 through the partition wall 216. The flow direction of the molten metal returning to the reservoir 102 through the outlet channel 208 is opposite to the flow direction of the molten metal flowing from the reservoir 102 through the inlet channel 206. Due to the countercurrent flow of the molten metal in the inlet channel 206 and the outlet channel 208, the molten metal can flow continuously through the filter elements 218A and 218B while minimizing the temperature drop. The continuous countercurrent flow extends the service life of the filter elements 218A and 218B by preventing the filter elements 218A and 218B from clogging prematurely.

[0039] Figure 2B2 is a schematic cross-sectional side elevation view of the filter device 200. The chamber 210 can achieve continuous or batch distribution of filtered molten metal to the die casting device 300 via a ladle, a plug rod, a launder or other known methods of extracting molten metal. The filter device 200 includes a cover 220 or a hood 220 located above the inlet channel 206 and the outlet channel 208 to minimize the heat energy loss of the molten metal. The top heating element 222 is arranged in the covered portion to maintain the temperature of the molten metal. Non-limiting examples of the top heating element 222 include a radiator-type heater, a gas-fired tubular heater, and a resistance heating element. A portion of the inner surface 204 of the filter device 200 can be lined with a refractory material 223 to minimize the heat loss of the molten metal.

[0040] An access port 224 is provided in the cover 220 to allow access to the plurality of filter elements 218A, 218B. The filter elements 218A, 218B may be selectively removed and replaced through the access port 224. At least one nozzle 226 is provided in the cover 220 for directing an inert gas 228, such as nitrogen or argon, into at least one of the inlet channel 206 and the outlet channel 208 to cover the surface 230 of the molten metal stream. The inert gas 228, also referred to as a cover gas, inhibits the formation of new oxides on the surface of the molten metal stream where the molten metal is exposed to air.

[0041] Figure 3300 is a schematic diagram of a die casting device 300. The die casting device 300 includes a die casting mold 302 having an inner surface 304 defining a mold cavity 306. The mold cavity 306 is used to receive the filtered molten metal from the chamber 210 of the filter device 200 to form an oversized casting having a predetermined shape of the mold cavity 306. The die casting device 300 also includes a plunger mechanism 308 and / or a pouring mechanism 340 for conveying the molten metal to a die casting storage cylinder system 312, and the die casting storage cylinder system 312 is used to convey the filtered molten metal to the mold cavity 306. The mold 302 is generally formed by two parts 302a, 302b, one of which is a fixed part 302a and the other is a movable part 302b, which is configured to facilitate the removal of the solidified casting. The particle size and content of oxides in the filtered alloy 105A are relatively low, which improves the mechanical properties of the solidified casting such as ultimate tensile strength, yield strength, elongation and fatigue life. The increase in elongation may eliminate the need for heat treatment in certain cast component applications. The ultra-low oxide content will improve the overall desired material properties. Although the die casting device 300 has been described, it should be understood that the die casting device 300 can be any casting device or casting mold that can receive the filtered metal alloy 105A to form a solidified object. Other objects include, but are not limited to, ingots, large ingots, bars and similar aluminum raw materials. Other casting devices include, but are not limited to, semi-permanent molds (SPM), sand casting devices, lost foam, and investment casting devices. The filter device 200 can be used in any casting process using molten aluminum.

[0042] Reference Figure 1-3 In a non-limiting example of the operation of the system 100, when the system is started, unfiltered molten metal 103 is introduced into the reservoir 102. The upstream pump 104A draws the unfiltered molten metal 103 from the reservoir 102 and pushes the unfiltered molten metal 103 through the inlet channel 206 and the filter elements 218A and 218B to produce the filtered molten metal 105A. In a continuous or batch dispensing process, a predetermined amount of the filtered molten metal 105A is delivered from the chamber 210 of the filter device 200 to the die casting device 300. The remaining portion of the filtered metal 105B flows through the chamber 210 and flows out of the filter device 200 through the outlet channel 208. The downstream pump 104B draws the unused filtered molten metal 105B from the chamber 210 and delivers the unused filtered molten metal 105B to the reservoir 102 through the outlet channel 208. During steady-state operation, the molten metal in the reservoir 102 is continuously supplemented with unfiltered molten metal 103 in an amount equal to the amount of filtered molten metal 105A removed from the filtering device 200, thereby forming a mixture 107 of filtered and unfiltered metal alloys in the reservoir 102. The mixture of unfiltered and filtered molten metals 107 from the reservoir 102 is continuously recycled through the filtering device 200, thereby providing the filtered molten metal 105A to the casting device.

[0043] Figure 4 1 is an illustration of a non-limiting example of an oversized casting 400 for a vehicle manufactured by the system 100. The oversized casting 400 shown is a casting for a structural underbody of a vehicle. Other examples of structural oversized castings include, but are not limited to, body panels, battery trays, and other load-bearing components having varying cross-sectional thicknesses. The oversized casting 400 may be designed and manufactured for on-road vehicles such as passenger cars, motorcycles, trucks and trailers, sport utility vehicles (SUVs), and recreational vehicles (RVs), as well as off-road vehicles such as boats, aircraft, commercial trucks, and the like.

[0044] As a non-limiting example, the super-large casting 400 can be manufactured by casting an aluminum-silicon (Al-Si) based alloy using the system 100. The filter device 200 filters the molten Al-Si alloy to remove any impurities, oxides, and other particles with a particle size greater than about 20 microns, thereby providing a homogeneous casting alloy to the die casting device 300. The device can be used to filter out aluminum-based alloy particles that do not contain silicon with a particle size as low as 5 microns. The plunger mechanism 308 injects the filtered molten metal 105A through the die casting cartridge system at a specified time and pressure to fill the mold cavity 306. The molten metal is cooled in the mold 302 to solidify and ejected from the mold 302. Then, the ejected solidified casting 400 is machined to the design size and tolerance, and heat treated as needed to reach the required specifications.

[0045] Ultra-large castings made from filtered casting alloys have ultra-low oxide content, providing excellent mechanical properties. In the metal casting industry, according to the porous circular filter analysis (PoDFA), if the inclusion content is less than 12mm 2 / kg, it is considered to have an ultra-low oxide content. Compared with the casting alloy material properties used in current computer-aided design (CAD), the ultimate tensile strength, yield strength, elongation and fatigue life are all improved. The higher cast elongation can eliminate the need for heat treatment in some applications. The ultra-low oxide content can improve fatigue performance and make the parts lighter, thereby increasing the mileage (mileage) of the vehicle, reducing emissions, and reducing the material cost of the parts.

[0046] The description of the present disclosure is merely exemplary in nature, and variations that do not depart from the general meaning of the present disclosure are intended to fall within the scope of the present disclosure. Such variations should not be regarded as departing from the spirit and scope of the present disclosure.

Claims

1. A molten metal filtering device, comprising: a housing having an inner surface defining an inlet passage, an outlet passage, and a chamber in fluid communication with the inlet passage and the outlet passage; and a first filter element disposed in the inlet passage; wherein the inlet channel is used to transport molten metal into the chamber, and the outlet channel is used to guide the molten metal out of the chamber; and Wherein, the first filter element comprises a shape factor occupying a cross-section of the inlet channel, the inlet channel being perpendicular to a flow direction of molten metal flowing through the inlet channel.

2. The molten metal filtering device according to claim 1, wherein: The chamber may enable a portion of the molten metal to be transferred from the chamber to a casting device.

3. The molten metal filtering apparatus of claim 1, further comprising a nozzle operable to direct an inert gas into at least one of the inlet channel and the outlet channel to cover the molten metal.

4. The molten metal filtering device according to claim 1, further comprising a second filter element disposed in the inlet passage downstream of the first filter element.

5. The molten metal filtering device according to claim 1, wherein: The outlet channel is adjacent to the inlet channel, and the two are separated by a heat conduction partition wall.

6. The molten metal filtering device according to claim 5, wherein: The outlet passage is used to convey the molten metal in a direction opposite to the flow direction of the molten metal flowing through the inlet passage.

7. The molten metal filtration apparatus of claim 1, further comprising at least one pump in fluid communication with at least one of the inlet passage and the outlet passage.

8. The molten metal filtering device according to claim 7, wherein: The at least one pump comprises: an upstream pump in fluid communication with the inlet passage, wherein the upstream pump is operable to push the molten metal through the inlet passage; and A downstream pump is in fluid communication with the outlet passage, wherein the downstream pump is operable to pump the molten metal from the outlet passage.

9. The molten metal filtering device according to claim 1, further comprising: A cover covers at least one of the inlet passage and the outlet passage, wherein the cover includes a removable opening to allow the first filter element to be selectively removed.

10. The molten metal filtering apparatus of claim 9, further comprising a heating element disposed within the housing and above at least one of the inlet passage and the outlet passage.

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