Method for preventing burning of residual magnesium alloy liquid in low-pressure pouring crucible

Abstract

The application relates to a method for preventing burning of residual magnesium alloy liquid in a low-pressure pouring crucible, and aims to solve the problem that burning of magnesium in a pouring mold is easy to cause burning of residual magnesium liquid in the crucible, leading to explosion of a tank body and existence of a major safety hazard. The method comprises the following steps: step one, placing a liquid lifting pipe flange on a liquid lifting pipe on a low-pressure pouring equipment mold; step two, equalizing the pressure in the low-pressure pouring equipment mold and the working tank before low-pressure pouring; step three, filling gas into the working tank when the pouring work starts; and step four, starting a pressure relief valve of the working tank to discharge the gas in the working tank after the low-pressure pouring equipment mold completes the pouring technical parameters and indexes. The application belongs to the field of magnesium alloy pouring forming.

Description

Technical Field

[0001] This invention relates to a method for preventing the combustion of molten magnesium during casting, specifically a method for preventing the combustion of residual molten magnesium alloy in a low-pressure casting crucible, belonging to the field of magnesium alloy casting molding. Background Technology

[0002] Oxidation and combustion during the casting of magnesium alloys remain the most prominent safety hazard. Uncontrolled combustion can lead to serious accidents involving equipment damage and personal injury. Typically, combustion occurs in two stages of magnesium alloy casting: first, during the alloy melting stage, combustion takes place within the crucible; second, during the casting stage, combustion occurs within the mold and risers. Under low-pressure casting conditions, because the magnesium alloy insulated crucible is sealed within the vessel and not directly exposed to the atmosphere, attention is often focused only on flame-retardant protection measures for the mold after casting, neglecting the protection of the remaining molten magnesium alloy within the crucible. In reality, after the low-pressure casting process ends and the liquid level is pressurized and depressurized, the molten magnesium alloy in the riser flows back into the crucible. At this point, the riser reconnects the casting system with the remaining molten magnesium in the crucible. If magnesium combustion occurs in the mold and gating system, the pressure generated by the combustion will force the combustion-supporting gas in the mold into the crucible, igniting the remaining molten magnesium. Even if no pressure-increasing combustion-supporting gas directly enters the crucible, the residual molten magnesium and oxide scale adhering to the inner wall of the riser pipe will burn, causing the remaining molten magnesium in the crucible to ignite. This kind of magnesium combustion within a confined space is extremely dangerous; if the pressure of the combustion gas inside the vessel becomes uncontrolled, it can lead to an explosion. Currently, low-pressure casting of magnesium alloys, lacking safety measures, poses a significant safety hazard. Summary of the Invention

[0003] The purpose of this invention is to address the problem that the combustion of magnesium in the casting mold can easily cause the remaining molten magnesium in the crucible to burn, leading to an explosion of the vessel and posing a significant safety hazard. Therefore, this invention provides a method to prevent the combustion of remaining molten magnesium alloy in a low-pressure casting crucible.

[0004] The aforementioned technical problem was solved through the following solution:

[0005] A method for preventing the combustion of residual molten magnesium alloy in a low-pressure casting crucible, the method comprising the following steps:

[0006] Step 1: Place the riser flange on the riser pipe onto the mold of the low-pressure casting equipment. Connect the baffle through hole on the limit baffle to the mold inlet hole of the low-pressure casting equipment. Insert the inlet end of the riser pipe into the liquid in the low-pressure casting magnesium alloy crucible inside the working tank.

[0007] Step 2: Before low-pressure casting, the pressure in the mold and working tank of the low-pressure casting equipment is equal. At this time, the sliding plug falls on the inner wall of the component housing according to its own weight and seals the bottom of the component housing.

[0008] Step 3: At the start of the casting process, gas is introduced into the working tank. Since the working tank is a closed space, the gas pressure inside the tank gradually increases. When the gas pressure is high enough, it forces the magnesium alloy liquid in the crucible to rise gradually along the riser pipe. As the magnesium alloy liquid level rises in the riser pipe, the air pressure sealed in the space from the sliding plug to the bottom of the riser pipe gradually increases. When the pressure increases to a level greater than the weight of the sliding plug, it will push the sliding plug to rise gradually. Under the action of the sliding support arm, the sliding plug slides along the component housing. When the sliding plug rises and detaches from the riser pipe, the gas and magnesium alloy liquid sealed in the riser pipe move upward through the channels around the sliding plug and enter the magnesium alloy liquid in the mold of the low-pressure casting equipment through the baffle through-hole. The magnesium alloy liquid in the crucible continuously enters the mold along the riser pipe to fill the mold.

[0009] Step 4: After the casting mold of the low-pressure casting equipment has completed the technical parameters and indicators for casting, the pressure relief valve of the working tank is started to release the gas in the working tank. When the pressure in the working tank is lower than or equal to the pressure in the mold, the sliding plug slides downward under its own weight and the weight of the magnesium alloy above the plug until it contacts the sealing surface of the component housing and blocks the inner hole of the riser pipe. The magnesium alloy liquid in the inner hole of the riser pipe below the sliding plug flows back into the crucible by its own weight. At this moment, the casting process is completed.

[0010] Furthermore, in step three, the continuously rising magnesium alloy liquid in the riser pipe pushes the sliding plug to rise and contact the limiting baffle. Under the pressure of the continuously rising magnesium alloy liquid, the sliding plug is limited and floats at this position, and at this moment the channel required for pouring is fully opened.

[0011] Furthermore, in step three, the sliding plug slides downward under its own weight and the weight of the magnesium alloy above it, and the magnesium alloy is in any of the following states: solid metal, liquid metal, or a mixture of solid metal and liquid metal.

[0012] The beneficial effects of this invention compared to the prior art are:

[0013] 1. This method for preventing the combustion of residual molten magnesium in the anti-gravity casting crucible of magnesium alloy castings automatically starts the working state by utilizing the pressure in the system during the casting process, without the need for manual operation, thus ensuring reliability.

[0014] 2. The implementation method has a simple structure, is easy to process and manufacture, and has low cost; it utilizes the self-lubricating properties of graphite or boron nitride materials, and the fact that the density of graphite and / or boron nitride materials is similar to that of magnesium alloy liquid. This solves the reliability problem of the plug sliding up and down under high temperature conditions.

[0015] 3. Graphite and / or boron nitride are non-metallic materials that do not react with molten magnesium alloy and will not contaminate the magnesium alloy. Furthermore, graphite and magnesium alloy do not bond together, making cleaning easy and allowing the structure to be reused.

[0016] 4. This method achieves isolation between the mold and the crucible, protecting the molten magnesium alloy inside the crucible and preventing combustion of the molten magnesium alloy inside the crucible and major accidents caused by combustion of the mold. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the component used in this application to prevent the combustion of residual magnesium alloy liquid in the low-pressure casting crucible. The diagram shows the sliding plug 2 installed inside the component housing 1 at the upper end of the riser pipe 7, and the plug position before casting.

[0018] Figure 2 This is a schematic diagram of the low-pressure casting process of the component used in this application to prevent the combustion of residual magnesium alloy liquid in the low-pressure casting crucible. The diagram shows the low-pressure casting process of the sliding plug 2 in the component housing 1 at the upper end of the riser pipe 7, and the schematic diagram of the sliding plug 2 rising along the component housing 1.

[0019] Figure 3 This is a schematic diagram of the component used in this application to prevent the combustion of residual magnesium alloy liquid in the low-pressure casting crucible after low-pressure casting. The diagram shows the sliding plug 2 sealing the component housing 1 at the upper end of the riser pipe 7, and the magnesium alloy liquid being sealed inside the component housing 1 by the sliding plug 2.

[0020] Figure 4 This is a schematic diagram showing multiple baffle through holes 5 on the limiting baffle 3.

[0021] Figure 5 This is a schematic diagram of the component housing 1, sliding plug 2, and limiting baffle 3.

[0022] Figure 6 This is a schematic diagram of component housing 1.

[0023] Figure 7 This is a schematic diagram of the sliding plug 2. Detailed Implementation

[0024] Specific implementation method one: Combining Figures 1-7This embodiment describes a component for preventing the combustion of residual molten magnesium alloy in a low-pressure casting crucible. It includes a component housing 1, a sliding plug 2, a limiting baffle 3, a riser flange 6, and a riser pipe 7. The riser flange 6 is installed at the top of the riser pipe 7 and integrally connected to it. The component housing 1 is located on the upper part of the riser pipe 7. The sliding plug 2 is located inside the component housing 1. The limiting baffle 3 is installed at the top of the component housing 1 and has multiple through holes. The bottom of the sliding plug 2 is in sealing contact with the inner wall of the component housing 1. The component housing 1 is sealed to the inner wall of the riser pipe 7, and the sliding plug 2 is slidably disposed within the component housing 1.

[0025] Specific Implementation Method Two: Combining Figure 5 and Figure 7 This embodiment describes a component for preventing the combustion of residual molten magnesium alloy in a low-pressure casting crucible. It further includes a plugging sliding support arm 4. Multiple plugging sliding support arms 4 are evenly distributed on the outer wall of the sliding plug 2. The sliding plug 2 slides vertically on the inner wall of the component housing 1 via these multiple plugging sliding support arms 4. A protrusion is provided at the top of the sliding plug 2, and a gap is provided between the protrusion and the limiting baffle 3 to ensure the flow of molten magnesium alloy. Other components and connection methods are the same as in specific embodiment one.

[0026] Specific implementation method three: Combining Figures 1-4 This embodiment describes a component for preventing the combustion of residual molten magnesium alloy in a low-pressure casting crucible. The limiting baffle 3 has multiple baffle through holes 5 machined on it, and these through holes 5 are evenly distributed radially on the limiting baffle 3. Other components and connection methods are the same as in specific embodiment two.

[0027] Specific implementation method four: Combination Figures 5-7 This embodiment describes a component for preventing the combustion of residual molten magnesium alloy in a low-pressure casting crucible. The bottom of the sliding plug 2 is machined with an inclined surface, and the inner wall of the component housing 1 is machined with a mating inclined surface. The inclined surface of the sliding plug 2 and the mating inclined surface of the component housing 1 are fitted together, achieving a seal between the sliding plug 2 and the component housing 1. Other components and connection methods are the same as in specific embodiment three.

[0028] Specific Implementation Method Five: Combining Figures 1-3 This embodiment describes a method for preventing the combustion of residual molten magnesium alloy in a low-pressure casting crucible. The method is implemented according to the following steps:

[0029] Step 1: Place the riser flange 6 on the riser pipe 7 on the mold of the low-pressure casting equipment. The baffle through hole 5 on the limit baffle 3 is connected to the liquid inlet hole of the mold of the low-pressure casting equipment. The liquid inlet end of the bottom of the riser pipe 7 is inserted into the liquid of the low-pressure casting magnesium alloy crucible in the working tank.

[0030] Step 2: Before low-pressure casting, the pressure in the mold and working tank of the low-pressure casting equipment is equal. At this time, the sliding plug 2 falls on the inner wall of the component housing 1 according to its own weight and seals the bottom of the component housing 1.

[0031] Step 3: At the start of the casting process, gas is introduced into the working tank. Since the working tank is a closed space, the gas pressure inside the tank gradually increases. When the gas pressure is high enough, it forces the magnesium alloy liquid in the crucible to rise gradually along the riser pipe 7. As the magnesium alloy liquid level rises in the riser pipe, the air pressure sealed in the space from the sliding plug to the bottom of the riser pipe gradually increases. When the pressure increases to a level greater than the weight of the sliding plug, it will push the sliding plug 2 to rise gradually. Under the action of the plug sliding support arm 4, the sliding plug 2 slides along the component housing 1. When the sliding plug 2 rises and separates from the riser pipe 7, the gas and magnesium alloy liquid sealed in the riser pipe move upward through the channels around the sliding plug 2 and enter the casting magnesium alloy liquid in the low-pressure casting equipment through the baffle through hole 5. The magnesium alloy liquid in the crucible continuously enters the casting mold along the riser pipe to fill the casting mold.

[0032] Step 4: After the casting mold of the low-pressure casting equipment has completed the technical parameters and indicators for casting, the pressure relief valve of the working tank is started to release the gas in the working tank. When the pressure in the working tank is lower than or equal to the pressure in the mold, the sliding plug 2 slides downward under its own weight and the weight of the magnesium alloy above the plug until it contacts the sealing surface of the component housing 1 and blocks the inner tube hole of the riser pipe 7. The magnesium alloy liquid in the inner tube hole of the riser pipe 7 below the sliding plug 2 flows back into the crucible by its own weight. At this moment, the casting process is completed.

[0033] Specific Implementation Method Six: Combination Figures 1-3 This embodiment describes a method for preventing the combustion of residual molten magnesium alloy in a low-pressure casting crucible. In step three, the continuously rising molten magnesium alloy in the riser pipe 7 pushes the sliding plug 2 upward to contact the limiting baffle 3. Under the pressure of the continuously rising molten magnesium alloy, the sliding plug 2 is limited and floats at this position, at which point the channel required for casting is fully opened. Other components and connection methods are the same as in specific embodiment five.

[0034] Specific implementation method seven: Combination Figures 1-3 This embodiment describes a method for preventing the combustion of residual molten magnesium alloy in a low-pressure casting crucible. In step three, the sliding plug 2 slides downwards under its own weight and the weight of the magnesium alloy above it. The magnesium alloy can be in any state of solid metal, liquid metal, or a mixture of solid and liquid metal. Other components and connection methods are the same as in specific embodiment five.

[0035] Specific implementation method eight: Combination Figure 6This embodiment describes a method for preventing the combustion of residual molten magnesium alloy in a low-pressure casting crucible. The component housing 1 is formed from graphite or boron nitride material. It is used to constrain the sliding of the sliding plug 2 and the flow of molten magnesium alloy. Other components and connection methods are the same as in specific embodiment five.

[0036] Specific Implementation Method Nine: Combining Figure 7 This embodiment describes a method for preventing the combustion of residual molten magnesium alloy in a low-pressure casting crucible. The sliding plug 2 is made of graphite or boron nitride, and the sliding support arm 4 on the sliding plug 2 is also made of graphite or boron nitride. The sliding plug 2 is used to block the riser pipe 7 after casting, isolating the crucible from the mold in the low-pressure casting equipment. Other components and connections are the same as in specific embodiment five.

[0037] Specific Implementation Method Ten: Combining Figure 4 This embodiment describes a method for preventing the combustion of residual molten magnesium alloy in a low-pressure casting crucible. The limiting baffle 3 is made of graphite or boron nitride material and is used to limit the upward movement of the sliding plug 2. Other components and connections are the same as in specific embodiment five.

Claims

1. A method of preventing burning of residual magnesium alloy melt in a low pressure pouring crucible, characterized by: The method is realized according to the following steps: Step one: the lifting tube flange (6) on the lifting tube (7) is placed on the casting mold of the low-pressure casting equipment, the baffle through hole (5) on the limiting baffle (3) is communicated with the liquid inlet hole of the casting mold of the low-pressure casting equipment, and the liquid inlet end at the bottom end of the lifting tube (7) is inserted into the low-pressure magnesium alloy crucible liquid in the working tank; Step two: the pressure in the working tank is equal to that in the casting mold before low-pressure casting, at this time, the sliding plug (2) falls on the inner side wall of the assembly shell (1) according to its own gravity and seals the bottom of the assembly shell (1); Step three: when the pouring work starts, the working tank is filled with gas, and since the working tank is a closed space, the gas pressure in the tank gradually increases, when the gas pressure is large enough, the magnesium alloy liquid in the crucible gradually rises along the lifting tube (7), and the air pressure enclosed in the space between the sliding plug and the bottom of the lifting tube gradually increases during the rising of the magnesium alloy liquid surface in the lifting tube, when the pressure increases to be greater than the weight of the sliding plug, the sliding plug (2) is gradually pushed up to make the sliding plug (2) slide up along the assembly shell (1) under the action of the plug sliding support arm (4), when the sliding plug (2) rises and separates from the lifting tube (7), the gas and magnesium alloy liquid enclosed in the lifting tube move upward through the channel around the sliding plug (2), enter the magnesium alloy liquid in the casting mold of the low-pressure casting equipment through the baffle through hole (5), and the magnesium alloy liquid in the crucible continuously enters the casting mold along the lifting tube to fill the casting mold; Step four: after the technical parameters and indexes of the casting mold of the low-pressure casting equipment are completed, the pressure relief valve of the working tank is started to discharge the gas in the working tank, when the pressure in the working tank is lower than or equal to the pressure in the casting mold, the sliding plug (2) slides downward under the action of its own gravity and the weight of the magnesium alloy above the plug, until it contacts with the sealing surface of the assembly shell (1) to block the pipe hole in the lifting tube (7) and achieve blocking, and the magnesium alloy liquid in the pipe hole of the lifting tube (7) below the sliding plug (2) flows back to the crucible by gravity, and the pouring process is completed at this moment.

2. The method for preventing the combustion of residual magnesium alloy liquid in a low-pressure pouring crucible according to claim 1, characterized in that: In step three, the continuously rising magnesium alloy liquid in the lifting tube (7) pushes the sliding plug (2) to rise and contact with the limiting baffle (3), and the sliding plug (2) is limited to float at this position under the action of the continuously rising magnesium alloy liquid pressure, at this moment, the required channel for pouring is completely opened.

3. The method for preventing the combustion of residual magnesium alloy liquid in a low-pressure pouring crucible according to claim 1, characterized in that: In step three, the sliding plug (2) slides downward under the action of its own gravity and the weight of the magnesium alloy above the plug, and the magnesium alloy is in any one state of solid metal, liquid metal or mixed state of solid metal and liquid metal.

4. The method for preventing the combustion of residual magnesium alloy liquid in a low-pressure pouring crucible according to claim 1, characterized in that: The assembly shell (1) is formed by graphite material or boron nitride material.

5. The method of claim 1, wherein the method further comprises: The sliding plug (2) is formed by graphite material or boron nitride material, and the plug sliding support arm (4) on the sliding plug (2) is formed by graphite material or boron nitride material. ​ 6. The method of claim 1, wherein the method further comprises: The limiting baffle (3) is formed by graphite material or boron nitride material. ​

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