Self-sealing flange structure and method for magnesium alloy injection molding

Abstract

The present application relates to the technical field of magnesium alloy injection molding equipment, and specifically discloses a self-sealing flange structure and method for magnesium alloy injection molding, the flange structure comprising a base assembly, a first sealing structure and a second sealing structure, the base assembly comprising a first flange and a second flange that are detachably connected, the two flanges combining to form a mounting groove, the first sealing structure comprising a sealing ring embedded in the mounting groove, the axial width of the sealing ring being greater than the axial width of the mounting groove, the sealing ring being capable of forming a mechanical seal through elastic deformation when compressed, the second sealing structure comprising a partial capture cavity formed by the corner of the sealing ring and the groove wall, and reaction gas pre-stored in the cavity, when the first sealing structure fails, the leaked magnesium alloy melt reacts with the reaction gas to form a solid product that blocks the leakage passage, through the dual mechanisms of mechanical sealing and reaction self-sealing, the problem of sealing attenuation and micro-leakage without inhibition caused by the high-temperature creep of the magnesium alloy flange is solved, and the safety performance is improved.

Description

Technical Field

[0001] This invention relates to the technical field of magnesium alloy injection molding equipment, and specifically to a self-sealing flange structure and method for magnesium alloy injection molding. Background Technology

[0002] When the magnesium alloy injection molding equipment is in operation, the connection between the nozzle flange and the barrel flange is exposed to a high temperature of over 650°C for a long time. The internal medium is liquid or semi-solid magnesium alloy melt. This working condition has four severe characteristics superimposed: high temperature, thermal cycling, creep, and high chemical activity of the medium. The sealing stability requirements of the flange connection are extremely high.

[0003] The following solutions are mainly used for existing magnesium alloy flange seals: Graphite gasket + steel ring + clamping flange (such as CN204997039U magnesium alloy quantitative furnace butt flange): The axial preload of the clamping flange compresses the graphite gasket to form a seal. Although the graphite gasket is resistant to high temperature, once it has been in service at high temperature for a long time, both the seal and the flange will experience creep and stress relaxation. After the preload decreases, micro-leakage is difficult to avoid. Moreover, this solution treats leakage as a fault, which can only be repaired by stopping the machine and disassembling. Sealing ring + sealing groove snap-fit ​​(such as CN202122878353.X magnesium alloy quantitative furnace docking flange): mechanical snap-fit ​​sealing is achieved by embedding the sealing ring into the sealing groove, but the sealing ring is prone to fatigue under thermal cycling load and has no mechanism to inhibit minor leakage. The common drawback of the above solutions is that they rely solely on initial mechanical pre-tightening or metal-to-metal contact stress to maintain a seal, lacking a self-sealing mechanism for minor leaks. Furthermore, magnesium alloy melts are highly chemically reactive at high temperatures, and once a minor leak occurs, it may react violently with air, posing a risk of oxidation, scaling, or even combustion. Simply relying on initial tightening is insufficient to guarantee long-term operational safety. Summary of the Invention

[0004] This invention addresses the aforementioned problems and aims to provide a self-sealing flange structure and method for magnesium alloy injection molding. It adopts an overall mold replacement approach and solves the problems of interference, alignment, and heavy load control during the mold replacement process of ultra-large molds through the coordinated design of the mold replacement vehicle, the docking of the mold bridge assembly, and the adjustment of mold support positioning. This improves the efficiency and versatility of mold replacement.

[0005] To achieve the above objectives, the present invention provides a self-sealing flange structure for magnesium alloy injection molding, comprising: The base assembly includes a first flange and a second flange, the second flange being detachably connected to the first flange, and the mating surfaces of the second flange and the first flange forming a mounting groove. The first sealing structure includes a sealing ring embedded in the mounting groove, the axial width of the sealing ring being greater than the axial width of the mounting groove, so that the sealing ring forms a mechanical seal through its own elastic deformation when the first flange and the second flange are pressed together; and The second sealing structure includes: A localized trapping cavity formed by at least one corner of the sealing ring and the groove wall of the mounting groove; and The reactant gas pre-retained within the local capture chamber; The local capture chamber is configured to capture leaked magnesium alloy melt when the first sealing structure fails, and to react it with the reactive gas to generate solid products to block the leakage channel.

[0006] The flange structure described above also includes a third sealing structure, which is formed by the mating surfaces of the first flange away from the mounting groove and the mating surfaces of the second flange away from the mounting groove being bonded together.

[0007] According to the flange structure described above, the axial preset interference of the sealing ring relative to the mounting groove is 0.05mm-0.2mm.

[0008] According to the flange structure described above, the axial width of the sealing ring is 9.8mm-10.2mm, and the axial width of the mounting groove is 9.6mm-10.15mm.

[0009] According to the flange structure described above, the sealing ring is made of metal.

[0010] According to the flange structure described above, the metal material is stainless steel or a nickel-based alloy.

[0011] According to the flange structure described above, the corners are set as transition fillets, and the radius of the transition fillets is 2mm-4mm.

[0012] According to the flange structure described above, the reacting gas is air.

[0013] According to the flange structure described above, the first flange and the second flange are detachably connected by bolts.

[0014] A method for achieving self-sealing using the flange structure described above includes the following steps: When the first sealing structure fails and causes the magnesium alloy melt to leak, the leaked magnesium alloy melt will enter the local capture cavity; The magnesium alloy melt reacts chemically with the pre-retained reactive gas in the local capture chamber to generate solid products, which are then used to plug the leak, forming a self-sealing seal.

[0015] The present invention has the following beneficial effects: 1. By utilizing the first sealing structure, the second sealing structure, and the third sealing structure, multiple seals are achieved between the first flange and the second flange. Furthermore, the second sealing structure is a self-sealing sealing structure, which can overcome the problem of attenuation caused by relying solely on pre-tightening force and improve the overall sealing performance and effect. 2. Actively utilizing the high chemical reactivity of magnesium alloys can transform leaks into a source of sealing materials, thus saving costs; 3. The local capture cavity formed by the sealing ring corner and the tank wall pre-retains the reaction gas, providing a reaction site and raw materials for the self-sealing reaction; 4. Under high-temperature conditions, it can still maintain its sealing ability, significantly reducing the safety risks of oxidation and combustion caused by magnesium alloy leakage; 5. Both the first and third sealing structures are detachable mechanical structures, which can still be inspected and repaired when necessary, and are compatible with existing maintenance practices. Attached Figure Description

[0016] Figure 1 This is a cross-sectional view of the overall structure of the embodiment; Figure 2 yes Figure 1 A magnified structural diagram at point A.

[0017] In the picture: 100. Base assembly; 110. First flange; 120. Second flange; 130. Mounting slot; 140. Bolt; 200. First sealing structure; 210. Sealing ring; 211. Transition fillet; 300. Second sealing structure; 310. Local capture chamber; 400. Third sealing structure. Detailed Implementation

[0018] The following are specific embodiments of the present invention, which are described in conjunction with the accompanying drawings to further illustrate the technical solution of the present invention. However, the invention is not limited to these embodiments.

[0019] like Figure 1-2As shown, a self-sealing flange structure for magnesium alloy injection molding is used as a whole at the nozzle flange and barrel flange connection part of a semi-solid magnesium alloy injection molding machine (also known as a magnesium alloy thixotropic injection molding machine). In actual production, the barrel assembly of this type of equipment needs to withstand high temperatures above 650 ℃ and the design life is often required to be in the range of 400,000 injection cycles. Therefore, the self-sealing flange structure must not only withstand the melt pressure, but also resist the creep and stress relaxation caused by long-term thermal cycling.

[0020] In this embodiment, the flange structure includes a base assembly 100, a first sealing mechanism, a second sealing structure 300, and a third sealing structure 400. The three sealing structures can provide triple sealing for the two flanges in the base assembly 100, thereby improving the sealing performance of the two flanges under high-temperature conditions, reducing the leakage of molten magnesium alloy, and reducing the risk of safety accidents caused by the leakage of molten magnesium alloy.

[0021] It includes a base assembly 100, a first sealing structure 200, a second sealing structure 300, and a third sealing structure 400. The three sealing structures can provide triple sealing for the two flanges in the base assembly 100, thereby improving the sealing performance of the two flanges under high-temperature conditions and preventing leakage of molten magnesium alloy.

[0022] Specifically, the base component 100 includes a first flange 110 and a second flange 120. In this embodiment, the first flange 110 is set as a nozzle flange, with its front end connected to the nozzle and its rear end face as a mating surface. The second flange 120 is set as a barrel flange, with its front end face as a mating surface and its rear end connected to the barrel. The first flange 110 and the second flange 120 are detachably connected by a plurality of bolts 140 evenly distributed around the circumference, and the mating surfaces of the first flange 110 and the second flange 120 form an installation groove 130.

[0023] In this embodiment, the mounting groove 130 is formed in three ways: One method is to set a half-groove on the mating surface of the first flange 110 and then set a half-groove on the mating surface of the second flange 120. When the two flanges are tightened by bolts 140, the two half-grooves close together along the axial direction to form an annular mounting groove 130. Another option is to provide a complete recessed area on the mating surface of the first flange 110. When the second flange 120 is tightened onto the first flange 110 by bolts 140, the mating surface on the second flange 120 seals the recessed area, thereby forming an annular mounting groove 130. The last method involves creating a complete recessed area on the mating surface of the second flange 120. When the first flange 110 is tightened onto the second flange 120 by bolts 140, the mating surface on the first flange 110 seals the recessed area, thereby forming an annular mounting groove 130.

[0024] Any of the above three methods can be chosen, with the first method being preferred. This method allows the two half-grooves to guide each other during the assembly of the first flange 110 and the second flange 120, preventing the sealing ring 210 from shifting radially.

[0025] Specifically, the first sealing structure 200 includes: The sealing ring 210 is embedded in the mounting groove 130. The axial width of the sealing ring 210 is greater than the axial width of the mounting groove 130. When the first flange 110 and the second flange 120 are pressed together, the sealing ring 210 forms a mechanical seal through its own elastic deformation. The sealing ring 210 undergoes controlled elastic (and local plastic) deformation under axial compression. The material flows to the micro-unevenness, machining marks and assembly gaps of the flange mating surface, filling the micro-unevenness and forming a continuous metal contact band. The sealing reliability reaches the level of metal ring gasket, ensuring that the first sealing structure 200 is not easy to fail.

[0026] In this embodiment, the sealing ring 210 is made of a metal material. Non-metallic materials such as stainless steel or nickel-based alloy rubber, PTFE, and graphite are unsuitable because they decompose, oxidize, or react with the carbon potential of magnesium melt at 650 ℃. Metals such as low-carbon steel, copper, titanium, and aluminum are also excluded because they either have insufficient yield, form brittle intermetallic compounds with magnesium, or have melting points close to the working temperature. Stainless steel and nickel-based alloys constitute the minimum complete set of materials for strength, toughness, and oxidation resistance under this working condition.

[0027] In this embodiment, the axial preset interference of the sealing ring 210 relative to the mounting groove 130 is 0.05mm-0.2mm. When the axial interference is less than 0.05mm, the plastic deformation of the sealing ring 210 under preload is insufficient to fill the micro-unevenness, machining marks and assembly gaps of the flange mating surface, and a continuous metal contact band cannot be formed, resulting in an inherent defect in the first mechanical seal. When the axial interference is greater than 0.20mm, the contact stress exceeds the controlled plastic deformation window of stainless steel / nickel-based alloy at 650℃, and the sealing ring 210 undergoes excessive plastic extrusion. The material flows into the magnesium melt channel along the edge of the groove wall or reverses the extrusion of the bolt 140, causing preload overload. At the same time, research on high-pressure metal O-rings has confirmed that excessive compression ratio will induce necking deformation, causing circumferential discontinuity of contact stress and leakage. In this embodiment, the upper limit is locked at 0.20mm, which is consistent with the recommended range of 10%-30% compression ratio for general design of metal sealing ring 210 in terms of equivalent strain.

[0028] Furthermore, the axial width of the sealing ring 210 is 9.8mm-10.2mm, and the axial width of the mounting groove 130 is 9.6mm-10.15mm. When the sealing ring 210 is at its upper limit of 10.2mm and the mounting groove 130 is at its upper limit of 10.15mm, the axial preset interference is δ = 0.05mm; when the sealing ring 210 is at its lower limit of 9.8mm and the mounting groove 130 is at its lower limit of 9.6mm, δ = 0.20mm; preferably, 10.1mm / 10.00mm corresponds to δ = 0.10mm. This dimensional combination transforms the abstract functional parameter of interference into two machinable, measurable, and inspectable physical dimensions.

[0029] Specifically, the second sealing structure 300 includes: The partial trapping cavity 310, formed by at least one corner of the sealing ring 210 and the groove wall of the mounting groove 130, in this embodiment, has a transition space between the upper corner of the sealing ring 210 and the upper groove wall of the mounting groove 130. This transition space constitutes the partial trapping cavity 310. When the first sealing structure 200 becomes loose, i.e., when there is a gap between the sealing ring 210 and the groove wall of the mounting groove 130, the magnesium soluble body will leak through this gap. Therefore, once the magnesium soluble body leaks, it will enter the partial trapping cavity 310. The second sealing structure 300 also includes: The reacting gas, pre-retained in the local capture chamber 310, is air, containing oxygen and nitrogen, both of which can chemically react with the magnesium molten material. The local capture chamber 310 is configured to capture leaked magnesium alloy molten material when the first sealing structure 200 fails, and allow it to react with the reacting gas to generate solid products that block the leakage path. The magnesium molten material penetrating into the local capture chamber 310 is primarily composed of Mg, which reacts with oxygen at high temperatures to form oxides. Magnesium oxide can react with nitrogen to form magnesium nitride. Magnesium oxide has a melting point of 2852℃, and magnesium nitride is a highly thermally stable ionic crystal. Both are high-melting-point solid products. Therefore, the infiltrated magnesium molten material will generate solid products after the reaction. These solid products will gradually fill the entire local capture cavity 310, thereby achieving self-sealing of the magnesium molten material leakage path. This prevents the magnesium molten material from flowing out to the outside, avoiding dangerous accidents. Moreover, no additional sealing structure is required. Self-sealing is achieved by utilizing the chemical reaction between the magnesium molten material and the reacting gas, saving costs.

[0030] Those skilled in the art will understand that when the flange structure is assembled under standard atmospheric pressure, air will naturally be retained in the physical space of the local trapping chamber 310 as a reactant gas without the need for additional steps. Therefore, pre-retention should be understood to include this state that naturally forms under normal assembly conditions.

[0031] In this embodiment, the reaction gas can be air, or it can be pure nitrogen, pure oxygen, or other gases that can react with the magnesium alloy melt at high temperature to generate solid products.

[0032] Furthermore, the corners are set as transition fillets 211, with a radius of 2mm-4mm. Setting transition fillets 211 can reduce the stress concentration factor, effectively eliminate stress concentration phenomena, and prevent breakage. At the same time, it also serves to construct the local capture cavity 310. The radius determines the volume of the local capture cavity 310, thereby determining the amount of retained reactive gas and the amount of depositable solid reactants.

[0033] In this embodiment, the corners of the sealing ring 210 can be either transition fillets 211, chamfers, multi-segment arcs, or other contours that can together with the mounting groove wall form a predetermined volume.

[0034] In this embodiment, the cross-sectional shape of the sealing ring 210 can be rectangular, circular, trapezoidal, or other shapes suitable for forming an axial seal.

[0035] Specifically, the third sealing structure 400 is formed by the mating surfaces of the first flange 110 away from the mounting groove 130 and the second flange 120 away from the mounting groove 130, and is used to provide a final barrier to prevent magnesium molten material from leaking out in the event that both the first sealing structure 200 and the second sealing structure 300 fail.

[0036] In this embodiment, if only the first sealing structure 200 is used, the failure situation described in the background art will occur. That is, once the first sealing structure 200 has been subjected to long-term high-temperature service, the seal and the flange will experience creep and stress relaxation. After the pre-tightening force decays, micro-leakage is difficult to avoid. Therefore, in this embodiment, a total of three sealing structures are provided to avoid leakage to the greatest extent.

[0037] In this embodiment, a method for achieving self-sealing using the flange structure described above is also protected, comprising the following steps: When the first sealing structure 200 fails and causes the magnesium alloy melt to leak, the leaked magnesium alloy melt will enter the local capture chamber 310. The magnesium alloy melt reacts chemically with the pre-retained reaction gas in the local capture chamber 310 to generate solid products, which are then used to plug the leak, forming a self-sealing seal.

[0038] The technical solution of the present invention has been described in detail above with reference to the accompanying drawings. The described embodiments are used to help understand the concept of the present invention. The specific embodiments described herein are merely illustrative examples of the spirit of the present invention. Those skilled in the art to which this invention pertains can make various modifications or additions to the described specific embodiments or use similar methods to replace them, but without departing from the spirit of the present invention or exceeding the scope defined by the appended claims.

[0039] It should be noted that all directional indications (such as up, down, left, right, front, back, etc.) in the embodiments of the present invention are only used to explain the relative positional relationship and movement of each component in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indication will also change accordingly.

[0040] Furthermore, in this invention, descriptions involving terms such as "first," "second," and "a" are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0041] In this invention, unless otherwise explicitly specified and limited, the terms "connection," "fixed," etc., should be interpreted broadly. For example, "fixed" can mean a fixed connection, a detachable connection, or an integral part; it can mean a mechanical connection or an electrical connection; it can mean a direct connection or an indirect connection through an intermediate medium; it can mean the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0042] Furthermore, the technical solutions of the various embodiments of the present invention can be combined with each other, but only if they are feasible for those skilled in the art. If the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such combination of technical solutions does not exist and is not within the scope of protection claimed by the present invention.

Claims

1. A self-sealing flange structure for magnesium alloy injection molding, characterized in that, include: The base assembly includes a first flange and a second flange, the second flange being detachably connected to the first flange, and the mating surfaces of the second flange and the first flange forming a mounting groove. The first sealing structure includes a sealing ring embedded in the mounting groove, the axial width of the sealing ring being greater than the axial width of the mounting groove, so that the sealing ring forms a mechanical seal through its own elastic deformation when the first flange and the second flange are pressed together; and The second sealing structure includes: A localized trapping cavity formed by at least one corner of the sealing ring and the groove wall of the mounting groove; and The reactant gas pre-retained within the local capture chamber; The local capture chamber is configured to capture leaked magnesium alloy melt when the first sealing structure fails, and to react it with the reactive gas to generate solid products to block the leakage channel.

2. The flange structure according to claim 1, characterized in that, It also includes a third sealing structure, which is formed by the mating surfaces of the first flange away from the mounting groove and the mating surfaces of the second flange away from the mounting groove.

3. The flange structure according to claim 1, characterized in that, The axial preset interference of the sealing ring relative to the mounting groove is 0.05mm-0.2mm.

4. The flange structure according to claim 1, characterized in that, The axial width of the sealing ring is 9.8mm-10.2mm, and the axial width of the mounting groove is 9.6mm-10.15mm.

5. The flange structure according to claim 1, characterized in that, The sealing ring is made of metal.

6. The flange structure according to claim 1, characterized in that, The metal material is stainless steel or a nickel-based alloy.

7. The flange structure according to claim 1, characterized in that, The corners are set as transition rounded corners, and the radius of the transition rounded corners is 2mm-4mm.

8. The flange structure according to claim 1, characterized in that, The reacting gas is air.

9. The flange structure according to claim 1, characterized in that, The first flange and the second flange are detachably connected by bolts.

10. A method for achieving self-sealing using the flange structure as described in any one of claims 1-9, characterized in that, Includes the following steps: When the first sealing structure fails and causes the magnesium alloy melt to leak, the leaked magnesium alloy melt will enter the local capture cavity; The magnesium alloy melt reacts chemically with the pre-retained reactive gas in the local capture chamber to generate solid products, which are then used to plug the leak, forming a self-sealing seal.

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