Die casting punch and magnesium alloy vacuum die casting apparatus

Abstract

The application provides a die-casting punch and a magnesium alloy vacuum die-casting equipment. The die-casting punch is used in cooperation with a pressure chamber of the magnesium alloy vacuum die-casting equipment. One end of the die-casting punch in a first direction is used to contact magnesium alloy liquid, and the other end is used to connect a power mechanism of the magnesium alloy vacuum die-casting equipment. The die-casting punch is formed with a protection gas channel, a protection gas inlet, a protection gas outlet, a cooling gas channel, a cooling gas inlet, and a cooling gas outlet. The cooling gas channel is connected with the cooling gas inlet and the cooling gas outlet. The protection gas channel is connected with the protection gas inlet and the protection gas outlet. The cooling gas channel and the protection gas channel are not communicated with each other. The protection gas outlet is used to deliver protection gas to the pressure chamber on one side of the magnesium alloy liquid. The die-casting punch has the protection gas channel and the cooling gas channel, can inhibit oxidation and combustion of the magnesium alloy liquid, improves production safety, and reduces the probability of explosion of the magnesium alloy liquid.

Description

Technical Field

[0001] This invention relates to the field of vacuum die casting, specifically to a die casting punch and a vacuum die casting device for magnesium alloys. Background Technology

[0002] Magnesium alloys are widely used in automobiles, aerospace, consumer electronics, and medical devices due to their advantages such as low density, high specific strength, good toughness, and good vibration damping.

[0003] Vacuum die casting of magnesium alloys is a core process in precision casting of magnesium alloys. Building upon die casting, it involves removing gas from the mold cavity and pressure chamber, allowing molten magnesium alloy to be poured under vacuum. This reduces porosity defects in the casting, increases the density of the casting structure, enhances its mechanical properties, and improves its surface quality. However, because magnesium is chemically reactive and magnesium alloys are prone to oxidation and combustion, while vacuum die casting reduces oxidation, residual oxygen and water vapor still have the potential to react with the molten magnesium alloy, affecting casting quality and posing safety risks.

[0004] During the die-casting process, the die-casting punch operates in a high-temperature, high-pressure, and high-speed environment, requiring proper cooling to extend its service life, reduce the probability of expansion and jamming, and ensure the quality of the castings. In related technologies, the cooling method for die-casting punches primarily involves internal cooling water channels. However, due to the harsh working environment of die-casting punches, there is a possibility of damage to these cooling water channels. If the leaking cooling water comes into contact with the molten magnesium alloy, it can cause an explosion of the magnesium alloy, posing a significant risk to equipment and personal safety. Summary of the Invention

[0005] One of the objectives of this invention is to provide a die-casting punch and a magnesium alloy vacuum die-casting equipment that can suppress the oxidation and combustion of molten magnesium alloy, improve production safety, and reduce the probability of molten magnesium alloy exploding.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows: This application provides a die-casting punch for use with the pressure chamber of a magnesium alloy vacuum die-casting equipment. One end of the die-casting punch in a first direction is used to contact the molten magnesium alloy, and the other end is used to connect to the power mechanism of the magnesium alloy vacuum die-casting equipment. The die-casting punch has a protective gas passage, a protective gas inlet, a protective gas outlet, a cooling gas passage, a cooling gas inlet, and a cooling gas outlet. The cooling gas passage connects the cooling gas inlet and the cooling gas outlet, and the protective gas passage connects the protective gas inlet and the protective gas outlet. The cooling gas passage and the protective gas passage are not interconnected. The protective gas outlet is used to deliver protective gas to the pressure chamber on the side where the molten magnesium alloy is located.

[0007] In some embodiments, the outer peripheral surface of the die-casting punch includes a first outer peripheral surface, a second outer peripheral surface, and a transition connecting surface, wherein the outer diameter of the first outer peripheral surface is larger than the outer diameter of the second outer peripheral surface, and the transition connecting surface connects the first outer peripheral surface and the second outer peripheral surface; The first outer peripheral surface is used to slide and form a fitting gap with the inner wall of the pressure chamber. The protective gas outlet is provided on the second outer peripheral surface and / or the transition connection surface. The fitting gap is used to prevent the magnesium alloy liquid from passing through and to guide the protective gas discharged from the protective gas outlet to the pressure chamber on the side where the magnesium alloy liquid is located.

[0008] In some embodiments, the protective air passage includes a guide cavity positioned above the axis of the die-casting punch and extending curvedly around the axis of the die-casting punch. The guide cavity extends upward through the outer peripheral surface of the die-casting punch to form the protective air outlet, so that the protective air outlet extends continuously above the outer peripheral surface of the die-casting punch.

[0009] In some embodiments, the protective airway includes multiple branch airways, one end of which is connected to the guide cavity and is spaced apart along the extension direction of the guide cavity, for introducing the protective gas from the protective air inlet into the guide cavity.

[0010] In some implementations, the cross-sectional area of ​​the branch air passages decreases along the airflow direction.

[0011] In some implementations, the protective airway includes a main airway, one end of which is connected to the air inlet, and the ends of the plurality of branch airways away from the guide cavity are all connected to the other end of the main airway.

[0012] In some implementations, a Laval nozzle structure is formed at one end of the main air passage near the branch air passage, and the cross-section of the Laval nozzle structure first decreases and then increases in the direction of airflow.

[0013] In some embodiments, the cooling air passage includes multiple spiral air passages surrounding the axis of the die-casting punch.

[0014] In some embodiments, the die-casting punch includes a working section, a transition section, and an mounting section arranged sequentially along a first direction. The end face of the working section is used to contact the molten magnesium alloy. The transition section connects the working section and the mounting section. The mounting section is used to connect a power mechanism. The working section, the transition section, and the mounting section are made of different materials, and the working section has a ceramic layer formed on at least its end face, with the ceramic layer having a wetting angle greater than 90° with the magnesium alloy liquid; the thermal conductivity of the transition section is greater than that of the mounting section.

[0015] In some implementations, the die-casting punch is a 3D-printed one-piece structure.

[0016] In some implementations, the working section is a multiphase ceramic-reinforced metal matrix composite material.

[0017] In some implementations, the thermal conductivity of the transition section is not less than 37 W / (m•K) at 500°C.

[0018] This application also provides a magnesium alloy vacuum die-casting equipment, including a pressure chamber, a vacuum system, a protective gas supply system, a cooling gas supply system, and a die-casting punch according to any embodiment of this application. The die-casting punch is disposed in the pressure chamber, the pressure chamber has a vacuum hole, the vacuum system is connected to the vacuum hole, the protective gas supply system is connected to the protective gas inlet, and the cooling gas supply system is connected to the cooling gas inlet.

[0019] In some embodiments, the magnesium alloy vacuum die-casting equipment includes a seal, an annular groove is formed on the outer peripheral surface of the die-casting punch, the radial inner end of the seal is accommodated in the annular groove, and the seal is gas-tightly fitted with the inner wall of the pressure chamber, so that the area enclosed by the inner wall of the pressure chamber, the first outer peripheral surface, the second outer peripheral surface, and the seal forms an annular air chamber, and the air chamber connects the protective air outlet and the fitting gap.

[0020] In some embodiments, the seal is a composite structure made of a metal matrix and a rubber material.

[0021] The die-casting punch of this embodiment has a protective gas channel and a cooling gas channel. The protective gas forms a protective gas curtain in the pressure chamber, covering the molten magnesium alloy and protecting it from oxidation and combustion. The cooling gas channel is used to achieve air cooling of the die-casting punch. Air cooling replaces the existing water cooling, which can improve production safety and reduce the probability of explosion of molten magnesium alloy. Attached Figure Description

[0022] Figure 1 A perspective view of a portion of the structure of the die-casting punch provided in an embodiment of this application; Figure 2 for Figure 1 A schematic diagram of the structure shown from another perspective; Figure 3 for Figure 1 A schematic diagram showing the outline of the protective air passage and the cooling air passage in the middle; Figure 4 for Figure 1 The cross-sectional view of the structure shown has the cutting plane perpendicular to the first direction and passes through the branch airway; Figure 5 for Figure 1Another cross-sectional view of the structure shown, wherein the cutting plane passes through the axis of the die-casting punch and a branch air passage. Figure 6 for Figure 5 A magnified view of a portion of the image; Figure 7 for Figure 1 The diagram shows the structure and components such as the protective gas supply system, the cooling gas supply system, and the seals. Figure 8 This is a cross-sectional schematic diagram of a portion of the structure of the magnesium alloy vacuum die-casting equipment provided in the embodiments of this application, wherein the cutting plane is parallel to... Figure 5 They are roughly the same.

[0023] Reference numerals: 1. Die-casting punch; 11. Protective air inlet; 12. Protective air passage; 121. Main air passage; 1211. Laval nozzle structure; 122. Branch air passage; 123. Guide chamber; 13. Protective air outlet; 14. Cooling air inlet; 15. Cooling air passage; 151. Cooling air inlet; 152. Cooling air outlet; 16. Cooling air outlet; 17. Working section; 171. Ceramic layer; 18. Transition section; 181. Annular groove; 19. Mounting section; 191. Anti-rotation spline; 2. Pressure chamber; 21. Inner wall; 22. Vacuum hole; 3. Protective gas supply system; 4. Cooling gas supply system; 41. Temperature sensor; 5. Seal; 6. Power mechanism; 7. Magnesium alloy liquid; A. First outer peripheral surface; B. Transition connection surface; C. Second outer peripheral surface; D. First direction; E. Air chamber. Detailed Implementation

[0024] The embodiments of the present invention will be described below with reference to the accompanying drawings and preferred embodiments. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be understood that the preferred embodiments are only for illustrating the present invention and not for limiting the scope of protection of the present invention.

[0025] It should be noted that the illustrations provided in the following embodiments are only schematic representations of the basic concept of the present invention. Therefore, the drawings only show the components related to the present invention and are not drawn according to the actual number, shape and size of the components in the actual implementation. In the actual implementation, the form, quantity and proportion of each component can be arbitrarily changed, and the layout of the components may also be more complex.

[0026] This application provides a die-casting punch 1 for use with the pressure chamber 2 of a magnesium alloy vacuum die-casting equipment. Please refer to... Figure 8The die-casting punch 1 has one end in the first direction D for contacting the molten magnesium alloy 7, and the other end for connecting to the power mechanism 6 of the magnesium alloy vacuum die-casting equipment. (See also...) Figure 1 The die-casting punch 1 has a protective air passage 12, a protective air inlet 11, a protective air outlet 13, a cooling air passage 15, a cooling air inlet 14, and a cooling air outlet 16. The cooling air passage 15 connects the cooling air inlet 14 and the cooling air outlet 16, and the protective air passage 12 connects the protective air inlet 11 and the protective air outlet 13. The cooling air passage 15 and the protective air passage 12 are not interconnected. That is to say, the gas in the cooling air passage 15 and the gas in the protective air passage 12 will not cross each other, the gas in the cooling air passage 15 will not enter the protective air passage 12, and the gas in the protective air passage 12 will not enter the cooling air passage 15.

[0027] The protective gas outlet 13 is used to supply protective gas to the pressure chamber 2 on the side where the molten magnesium alloy 7 is located. That is, the external protective gas enters the protective gas passage 12 from the protective gas inlet 11, flows through the protective gas passage 12, exits from the protective gas outlet 13, and finally flows to the pressure chamber 2 on the side where the molten magnesium alloy 7 is located. It should be noted that the protective gas refers to a gas that will not react with the molten magnesium alloy 7 and will not cause the molten magnesium alloy 7 to undergo violent oxidation, combustion, or other phenomena.

[0028] The first direction D is parallel to the direction of movement of the die-casting punch 1 in the pressure chamber 2.

[0029] It should be noted that the gas discharged from the cooling outlet 16 will not enter the gas chamber E on the side where the magnesium alloy liquid 7 is located.

[0030] The magnesium alloy liquid 7 in this embodiment can be a pure liquid or a semi-solid mixture of solid and liquid phases.

[0031] Cooling gas (hereinafter referred to as cooling gas) is introduced into the cooling air passage 15 to achieve air cooling of the die-casting punch 1. The cooling gas cools the die-casting punch 1 as it flows through the cooling air passage 15.

[0032] The cooling gas can be compressed air.

[0033] The die-casting punch 1 of this embodiment has a protective gas channel 12 and a cooling gas channel 15. The protective gas forms a protective gas curtain in the pressure chamber 2, covering the magnesium alloy liquid 7 and protecting it from oxidation and combustion. The cooling gas channel 15 is used to achieve air cooling of the die-casting punch 1. Air cooling replaces the existing water cooling, which can improve production safety and reduce the probability of the magnesium alloy liquid 7 exploding.

[0034] In some embodiments, please refer to Figure 1The outer peripheral surface of the die-casting punch 1 includes a first outer peripheral surface A, a second outer peripheral surface C, and a transition connecting surface B. The outer diameter of the first outer peripheral surface A is larger than the outer diameter of the second outer peripheral surface C. The transition connecting surface B connects the first outer peripheral surface A and the second outer peripheral surface C. The first outer peripheral surface A is used to slide and form a clearance with the inner wall 21 of the pressure chamber 2. The protective vent 13 is located on the second outer peripheral surface C and / or the transition connecting surface B. The clearance is used to prevent the magnesium alloy liquid 7 from passing through and to guide the protective gas discharged from the protective vent 13 to the side of the pressure chamber 2 where the magnesium alloy liquid 7 is located. That is to say, the clearance must allow the die-casting punch 1 to move in the pressure chamber 2 along the first direction D and allow the protective gas to flow, but it must not allow the magnesium alloy liquid 7 to flow in.

[0035] Since the outer diameter of the second outer peripheral surface C is smaller than the outer diameter of the first outer peripheral surface A, the location of the protective gas outlet 13 can both smoothly discharge the protective gas and reduce the probability of the protective gas outlet 13 being blocked.

[0036] It should be noted that in some embodiments, the protective vent 13 is only provided on the second outer peripheral surface C and not on the transition connection surface B; in other embodiments, the protective vent 13 is only provided on the transition connection surface B and not on the second outer peripheral surface C; in still other embodiments, a portion of the protective vent 13 is provided on the second outer peripheral surface C and another portion is provided on the transition connection surface B.

[0037] The intersection of transition surface B and the first outer peripheral surface A can be a right angle or a chamfered transition. Similarly, the intersection of transition surface B and the second outer peripheral surface C can be a right angle or a chamfered transition.

[0038] As one embodiment, the protective gas is a ternary protective gas. For example, the protective gas can be a ternary protective gas composed of sulfur hexafluoride, carbon dioxide, and nitrogen.

[0039] In some embodiments, please refer to Figure 1 The die-casting punch 1 includes a working section 17, a transition section 18, and a mounting section 19 arranged sequentially along a first direction D. The end face of the working section 17 (i.e., the end face away from the transition section 18 in the first direction D) is used to contact the molten magnesium alloy 7. The transition section 18 connects the working section 17 and the mounting section 19, and the mounting section 19 is used to connect the power mechanism 6. The working section 17, transition section 18, and mounting section 19 are made of different materials, and the working section 17 has at least one ceramic layer 171 formed on its end face, with a wetting angle between the ceramic layer 171 and the molten magnesium alloy 7 greater than 90°. The thermal conductivity of the transition section 18 is greater than that of the mounting section 19.

[0040] The working section 17, transition section 18, and installation section 19 can be made of different materials to meet the performance requirements of different working conditions.

[0041] The end face of the working section 17 is in direct contact with the molten magnesium alloy 7. On the one hand, the wetting angle between the ceramic layer 171 and the molten magnesium alloy 7 is greater than 90°, making it difficult for the molten magnesium alloy 7 to wet the surface of the ceramic layer 171. This eliminates the need for lubricant spraying, achieving a good anti-sticking effect, reducing lubricant contamination of the molten magnesium alloy 7, and improving safety and casting quality. On the other hand, the ceramic layer 171 has poor thermal conductivity, which slows down the heat transfer from the molten magnesium alloy 7 to the die-casting punch 1, reducing the temperature rise of the working section 17. For example, if the pouring temperature of the molten magnesium alloy 7 is 620℃~680℃, and the working section 17 is in direct contact with the molten magnesium alloy 7, the instantaneous peak contact temperature will not exceed 550℃.

[0042] As one embodiment, a ceramic layer 171 can also be provided on the peripheral sidewall of the working section 17. On the one hand, this can further reduce the temperature rise of the working section 17. On the other hand, since part of the peripheral sidewall of the working section 17 is frequently rubbed against the inner wall 21 of the pressure chamber 2, the ceramic layer 171 has high hardness and good wear resistance, which is beneficial to improving the service life of the die-casting punch 1.

[0043] The transition section 18 is the main heat dissipation area of ​​the die-casting punch 1, which quickly transfers the heat from the working section 17. Since the transition section 18 has a high thermal conductivity, the heat can be quickly carried away by the cooling gas flowing in the cooling air passage 15, thereby improving the heat dissipation performance.

[0044] As the part connected to the power mechanism 6, the mounting section 19 needs to provide a stable bearing foundation for the reciprocating motion of the die-casting punch 1. Therefore, it needs to ensure good structural rigidity, impact resistance and thermal fatigue performance.

[0045] In this embodiment, by using working section 17, transition section 18, and installation section 19 made of different materials, the requirements of preventing magnesium alloy liquid 7 from sticking, good heat dissipation performance, and assembly strength with power mechanism 6 can be taken into account.

[0046] In some embodiments, the die-casting punch 1 is a 3D (Three-Dimensional) printed integrated structure. That is, the working section 17, the transition section 18, and the mounting section 19 are formed into an integrated structure using 3D printing technology. This also facilitates the formation of complex air passages inside the die-casting punch 1.

[0047] In some embodiments, working segment 17 is a multiphase ceramic-reinforced metal matrix composite material. Multiphase ceramics refer to the synergistic combination of two or more ceramic phases (which can be in the form of particles, whiskers, nanophases, etc.) rather than a single ceramic, and can also be called a hybrid ceramic reinforcement phase. Multiphase ceramic-reinforced metal matrix composite materials use a metal alloy as a continuous matrix, with two or more ceramic phases uniformly dispersed in a three-dimensional network distribution, forming an integrated composite material through interfacial bonding.

[0048] For example, the multiphase ceramic-reinforced metal matrix composite material can be an aluminum alloy matrix with composite alumina and silicon carbide ceramic phases. Alumina has high hardness and wear resistance, while silicon carbide has high hardness, high strength, and good chemical stability. The combination of the two can adapt to the high-pressure, high-temperature, and high-speed operating conditions of the working section 17. In some embodiments, the protective air inlet 11, the cooling air inlet 14, and the cooling air outlet 16 are all located on the end face of the mounting section 19 away from the transition section 18, which facilitates the connection of the corresponding protective gas supply system 3 and cooling gas supply system 4.

[0049] It should be noted that the intersection of working segment 17 and transition segment 18 is not necessarily related to the position of transition connection surface B. Part or all of the outer peripheral surface of working segment 17 in the first direction D is the first outer peripheral surface A.

[0050] As one example, gradient powder feeding technology can be used to achieve seamless integration between the working section 17, the transition section 18, and the installation section 19, reducing the probability of problems such as interlayer peeling and cracking caused by material abrupt changes, while also helping to reduce the overall manufacturing cost and balancing performance and economy.

[0051] In some embodiments, the proportion of ceramic components in the working section 17 gradually increases from the inside to the outside, so as to form a ceramic layer 171 on the surface of the working section 17. The interior of the working section 17 is mainly composed of metal components, which are tough and impact resistant.

[0052] In some embodiments, the thermal conductivity of the transition section 18 is not less than 37 W / (m•K) at 500°C, where W is in watts, m is in meters, and K is in Kelvin. This ensures that the transition section 18 has good thermal conductivity. It should be noted that this refers to the thermal conductivity of the transition section 18 measured under conditions where the temperature of the transition section 18 is raised to 500°C during testing.

[0053] In some embodiments, the material of the transition section 18 may be modified martensitic aging steel.

[0054] In some embodiments, the material of the mounting section 19 can be hot work die steel, which has good load-bearing capacity, excellent high-temperature toughness and fatigue resistance, and is suitable for connecting the power mechanism 6 and transmitting power.

[0055] As one example, please refer to Figure 2 The installation section 19 includes an anti-rotation spline 191, which is used to connect the power mechanism 6. The anti-rotation spline 191 can realize the circumferential limit of the die-casting punch 1, reduce the circumferential rotation of the die-casting punch 1 during the die-casting process, and help ensure the normal operation of the die-casting punch 1.

[0056] In some embodiments, please refer to Figure 4The protective air passage 12 includes a guide cavity 123, which is positioned above the axis of the die-casting punch 1 and extends in a curved manner around the axis of the die-casting punch 1. Please refer to [link to relevant documentation]. Figure 5 and Figure 6 The guide cavity 123 extends upward through the outer peripheral surface of the die-casting punch 1 to form a protective vent 13, so that the protective vent 13 extends continuously in the upper part of the outer peripheral surface of the die-casting punch 1. The guide cavity 123 collects the incoming protective gas and makes the outgoing protective gas continuously distributed along the upper part of the outer peripheral surface of the die-casting punch 1. This is beneficial to forming a relatively continuous protective air curtain in the upper part of the outer periphery of the die-casting punch 1.

[0057] In some embodiments, please refer to Figure 4 The protective air duct 12 includes multiple branch air ducts 122, one end of which is connected to the guide cavity 123 and is arranged at intervals along the extension direction of the guide cavity 123. These branch air ducts are used to guide the protective gas from the protective air inlet 11 into the guide cavity 123. This improves the uniformity of the airflow in the guide cavity 123 along the extension direction, thereby improving the uniformity of the gas flow at the protective air outlet 13 along the extension direction.

[0058] In one embodiment, there are five protective gas channels 12, which are symmetrically and evenly distributed circumferentially within a 60° range above the die-casting punch 1. This distribution facilitates the uniform flow of protective gas into the guide cavity 123.

[0059] In some embodiments, please refer to Figure 5 Along the direction of airflow, the cross-sectional area of ​​the branch airway 122 decreases. This structure facilitates the formation of a microporous throttling structure and a unidirectional flow structure in the branch airway, promotes the smooth flow of protective gas to form a stable and continuous protective air curtain, and helps maintain the unidirectional flow of protective gas, inhibiting the entry of magnesium alloy liquid 7 and reducing blockage of the branch pipes.

[0060] In some embodiments, the end of each branch duct away from the flow chamber 123 may be connected to multiple protective air inlets 11.

[0061] In other embodiments, please refer to Figure 3 The protective airway 12 includes a main airway 121, one end of which is connected to a protective air inlet 11. Multiple branch airways 122, with their ends furthest from the guide cavity 123, are all connected to the other end of the main airway 121. Protective gas enters the main airway 121 through a protective air inlet 11, and the main airway 121 then distributes the protective gas to multiple branch airways 122. This reduces the number of protective air inlets 11 and facilitates pipe connection. It should be noted that... Figure 3 The diagram only illustrates the outlines of the protective air duct 12 and the cooling air duct 15, and does not specifically indicate that the protective air duct 12 and the cooling air duct 15 are pipelines.

[0062] As one embodiment, the main air passage 121 is arranged along the axis of the die-casting punch 1, and multiple branch air passages 122 are distributed in a fan shape on a plane perpendicular to the axis.

[0063] In some embodiments, please refer to Figure 5 A Laval nozzle structure 1211 is formed at one end of the main air passage 121 near the branch air passage 122. The cross-section of the Laval nozzle structure 1211 first decreases and then increases in the direction of airflow. The Laval nozzle structure 1211 can increase the flow velocity of the protective gas.

[0064] In some embodiments, please refer to Figure 3 The cooling air passage 15 includes multiple spiral passages surrounding the axis of the die-casting punch 1. The multiple spiral passages can increase the effective length of the cooling air passage 15 within a limited space, thereby increasing the heat exchange time between the cooling gas and the die-casting punch 1 and improving the cooling effect.

[0065] As one embodiment, the cooling air passage 15 includes a cooling air inlet passage 151 and a cooling air outlet passage 152. The cooling air inlet passage 151 is located close to the outer wall of the die-casting punch 1, which is beneficial to enhance the cooling effect. The cooling air outlet passage 152 is located inside the cooling air inlet passage 151 and is used to discharge cooling gas, while also having a cooling effect on the inside of the die-casting punch 1.

[0066] As one embodiment, the inner wall of the cooling air passage 15 is rough, which can enhance the heat exchange effect between the cooling gas and the die-casting punch 1 and further improve the cooling efficiency.

[0067] This application provides an embodiment of a magnesium alloy vacuum die-casting device. Please refer to [link to relevant documentation]. Figure 8 The system includes a pressure chamber 2, a vacuum system, a protective gas supply system 3, a cooling gas supply system 4, and a die-casting punch 1 according to any embodiment of this application. The die-casting punch 1 is disposed in the pressure chamber 2, which has a vacuum hole 22. The vacuum system is connected to the vacuum hole 22, the protective gas supply system 3 is connected to the protective gas inlet 11, and the cooling gas supply system 4 is connected to the cooling gas inlet 14. It should be noted that when the cooling gas is a harmless gas such as compressed air, the cooling gas outlet 16 can be discharged directly into the surrounding environment without a pipeline; of course, a pipeline can also be connected to the cooling gas outlet 16 to guide the gas discharged from the cooling gas outlet 16 to a suitable place for treatment.

[0068] The protective gas supply system 3 and the cooling gas supply system 4 are independent of each other, which is beneficial to control and adjust the intake volume of protective gas and cooling gas respectively during the entire magnesium alloy vacuum die casting process.

[0069] The magnesium alloy vacuum die-casting equipment of this application, with the vacuum system and protective gas supply system 3 working together, can effectively reduce the oxidation and combustion of magnesium alloy liquid 7 and improve the quality of castings; the cooling gas supply system 4 can effectively cool the die-casting punch 1, improve the service life of the die-casting punch 1, and the air cooling replaces water cooling, improving the safety of the die-casting process.

[0070] As one embodiment, the cooling gas supply system 4 includes a temperature sensor 41 and a controller. The temperature sensor 41 can monitor the temperature of at least one of the working section 17, the transition section 18, and the installation section 19 in real time. The controller adjusts the intake volume and flow rate of the cooling gas according to the temperature data of the temperature sensor 41. When the temperature is higher than a preset threshold, the intake volume of the cooling gas is increased to improve the cooling efficiency and stabilize the temperature of the die-casting punch 1 within the working range.

[0071] As one embodiment, the protective gas supply system 3 includes a protective gas storage cylinder, a flow regulating valve, a pressure sensor, and a solenoid valve. The protective gas storage cylinder contains protective gas, the flow regulating valve is used to regulate the intake of protective gas, the pressure sensor monitors the gas pressure in the protective gas passage 12 in real time, and the solenoid valve realizes the on / off of protective gas to prevent excessive protective gas from entering the magnesium alloy liquid 7 and causing the risk of air entrapment, thus ensuring the quality of the casting.

[0072] In some embodiments, the intake volume of the protective gas supply system 3 is preset to be 1 / 2 to 1 / 4 of the pumping volume of the vacuum system. Excessive intake of the protective gas will result in insufficient vacuum in the pressure chamber 2 and waste of the protective gas. Insufficient intake of the protective gas will result in insufficient formation of a continuous protective gas curtain, preventing the protective gas from exerting its flame-retardant effect. This numerical range is a reasonable range that balances the vacuum requirements of the pressure chamber 2 with the formation of a continuous protective gas curtain.

[0073] As one embodiment, the intake volume of the protective gas supply system 3 is 1 / 3 of the pumping volume of the vacuum system. Compared with the scheme of introducing the same amount of protective gas as the pumping volume, it can save about 60% of the protective gas.

[0074] In some embodiments, please refer to Figure 7 and Figure 8 The magnesium alloy vacuum die casting equipment includes a seal 5. An annular groove 181 is formed on the outer peripheral surface of the die casting punch 1. The radial inner end of the seal 5 is accommodated in the annular groove 181. The seal 5 is used to gas seal with the inner wall 21 of the pressure chamber 2 to protect the position of the air outlet 13 on the outer surface of the die casting punch 1 from the annular groove 181, which is closer to the side where the magnesium alloy liquid 7 is located.

[0075] The seal 5 can not only block the protective gas from flowing backward and ensure the stability of the protective air curtain formed at the front end of the working section 17, but also prevent external impurities from entering the air chamber E below through the fitting gap, which is conducive to ensuring the cleanliness of the pressure chamber 2.

[0076] In some specific embodiments, the area enclosed by the inner wall 21 of the pressure chamber 2, the first outer peripheral surface A, the second outer peripheral surface C, and the sealing element 5 forms an annular air chamber E, which connects to the protective air outlet 13 and the fitting clearance.

[0077] In some embodiments, the seal 5 is a composite structure made of a metal matrix and a rubber material. The metal matrix can improve the structural strength of the seal 5, while the rubber material has good sealing performance. The composite seal 5 has a long service life and is not prone to sealing failure.

[0078] As one embodiment, the seal 5 has a labyrinth seal structure, which enhances the sealing effect of the seal 5 and effectively reduces leakage and failure.

[0079] As one embodiment, the rubber material is fluororubber, which possesses excellent high-temperature resistance and corrosion resistance. The tail temperature of the mounting section 19 without cooling can reach 280°C to 350°C, while in this embodiment, the temperature of the mounting section 19, after cooling, is stably maintained at 180°C to 220°C. The long-term operating temperature range of fluororubber can reach 250°C, which is higher than the temperature of the mounting section 19. Fluororubber is less prone to aging, carbonization, and seal failure, thus meeting the service life requirements of the seal 5.

[0080] The workflow of a magnesium alloy vacuum die-casting equipment according to an embodiment of this application includes the following steps: (1) Preparation before vacuum die casting: Place the die casting punch 1 in the pressure chamber 2, check the fit clearance between the first outer peripheral surface A and the inner wall 21 of the pressure chamber 2, fix the mounting section 19 to the power mechanism 6, check the sealing performance of the sealing element 5, and ensure that the vacuum system, protective gas supply system 3 and cooling gas supply system 4 are operating normally; start the vacuum system, extract the air in the pressure chamber 2 through the vacuum hole 22 to form a vacuum environment, and at the same time set the protective gas intake of the protective gas supply system 3 to 1 / 3 of the air extraction volume of the pressure chamber 2.

[0081] (2) Positioning of die-casting punch 1 and pre-charging of protective gas: Die-casting punch 1 is reset to the initial position. The protective gas supply system 3 fills the die-casting punch 1 with protective gas through the protective gas channel 12 to accelerate the air discharge. When the magnesium alloy liquid 7 rises in the pressure chamber 2 to about 5 mm below the lowest point of the main gas channel 121, that is, when the distance H from the lowest point of the main gas channel 121 to the liquid surface of the magnesium alloy liquid 7 is 5 mm, the solenoid valve of the protective gas supply system 3 is closed to stop filling the protective gas. At this time, a protective gas curtain is formed above the magnesium alloy liquid 7.

[0082] (3) Die casting operation: The die casting punch 1 moves forward, and the ceramic layer 171 of the working section 17 comes into contact with the magnesium alloy liquid 7. The adhesion of the magnesium alloy liquid 7 can be reduced without the need for spraying lubricating oil. The first outer peripheral surface A and the inner wall 21 of the pressure chamber 2 form a fitting gap to prevent the magnesium alloy liquid 7 from seeping in. The cooling gas supply system 4 fills the cooling gas inlet 14 with cooling gas. The cooling gas flows in the cooling gas channel 15 and exchanges heat with the die casting punch 1, quickly removing the heat from the die casting punch 1 and effectively cooling the die casting punch 1 to ensure the temperature stability of the die casting punch 1. The protective air curtain isolates the magnesium alloy liquid 7 from the air, inhibiting the oxidation and combustion of the magnesium alloy liquid 7. At the same time, the protective air outlet 13 and the branch air channel 122 can prevent the magnesium alloy liquid 7 from flowing back and blocking the protective air channel 12. The protective gas supply system 3 monitors the outlet pressure in real time and dynamically adjusts the intake volume of the protective gas. The cooling gas supply system 4 monitors the temperature of the die-casting punch 1 in real time and dynamically adjusts the intake volume and flow rate of the cooling gas to stabilize the temperature of the die-casting punch 1 within the working range.

[0083] (4) Die casting completion and reset: After the casting is formed, the die casting punch 1 is reset, and the cooling gas supply system 4 continues to supply gas for a period of time to cool the die casting punch 1 with residual heat. After the temperature of the die casting punch 1 drops to a safe range, the supply of cooling gas is stopped. One die casting cycle is completed, and the next round of operation cycle begins.

[0084] The above embodiments are merely preferred embodiments provided to fully illustrate the present invention, and the scope of protection of the present invention is not limited thereto. Equivalent substitutions or modifications made by those skilled in the art based on the present invention are all within the scope of protection of the present invention.

Claims

1. A die-casting punch, characterized in that, For use with the pressure chamber of a magnesium alloy vacuum die-casting equipment, the die-casting punch is used to contact the molten magnesium alloy at one end in the first direction, and to connect to the power mechanism of the magnesium alloy vacuum die-casting equipment at the other end. The die-casting punch has a protective air passage, a protective air inlet, a protective air outlet, a cooling air passage, a cooling air inlet, and a cooling air outlet. The cooling air passage connects the cooling air inlet and the cooling air outlet, and the protective air passage connects the protective air inlet and the protective air outlet. The cooling air passage and the protective air passage are not interconnected. The protective air outlet is used to deliver protective gas to the pressure chamber on the side where the magnesium alloy liquid is located.

2. The die-casting punch according to claim 1, characterized in that, The outer peripheral surface of the die-casting punch includes a first outer peripheral surface, a second outer peripheral surface, and a transition connecting surface. The outer diameter of the first outer peripheral surface is larger than the outer diameter of the second outer peripheral surface, and the transition connecting surface connects the first outer peripheral surface and the second outer peripheral surface. The first outer peripheral surface is used to slide and form a fitting gap with the inner wall of the pressure chamber. The protective gas outlet is provided on the second outer peripheral surface and / or the transition connection surface. The fitting gap is used to prevent the magnesium alloy liquid from passing through and to guide the protective gas discharged from the protective gas outlet to the pressure chamber on the side where the magnesium alloy liquid is located.

3. The die-casting punch according to claim 1, characterized in that, The protective air passage includes a guide cavity, which is positioned above the axis of the die-casting punch and extends curvedly around the axis of the die-casting punch. The guide cavity extends upward through the outer peripheral surface of the die-casting punch to form the protective air outlet, so that the protective air outlet extends continuously in the upper part of the outer peripheral surface of the die-casting punch.

4. The die-casting punch according to claim 3, characterized in that, The protective airway includes multiple branch airways, one end of which is connected to the guide cavity and is arranged at intervals along the extension direction of the guide cavity, for introducing the protective gas from the protective air inlet into the guide cavity.

5. The die-casting punch according to claim 4, characterized in that, Along the direction of airflow, the cross-sectional area of ​​the branch air passages decreases.

6. The die-casting punch according to claim 4, characterized in that, The protective airway includes a main airway, one end of which is connected to the air inlet, and the ends of the multiple branch airways that are away from the guide cavity are all connected to the other end of the main airway.

7. The die-casting punch according to claim 6, characterized in that, A Laval nozzle structure is formed at one end of the main air passage near the branch air passage. The cross-section of the Laval nozzle structure first decreases and then increases in the direction of airflow.

8. The die-casting punch according to claim 1, characterized in that, The cooling air passage includes multiple spiral air passages surrounding the axis of the die-casting punch.

9. The die-casting punch according to claim 1, characterized in that, The die-casting punch includes a working section, a transition section, and an installation section arranged sequentially along a first direction. The end face of the working section is used to contact the molten magnesium alloy. The transition section connects the working section and the installation section. The installation section is used to connect the power mechanism. The working section, the transition section, and the mounting section are made of different materials, and the working section has a ceramic layer formed on at least its end face, with the ceramic layer having a wetting angle greater than 90° with the magnesium alloy liquid; the thermal conductivity of the transition section is greater than that of the mounting section.

10. The die-casting punch according to claim 9, characterized in that, The die-casting punch is a 3D-printed one-piece structure.

11. The die-casting punch according to claim 9, characterized in that, The working section is a multiphase ceramic-reinforced metal matrix composite material.

12. The die-casting punch according to claim 9, characterized in that, The thermal conductivity of the transition section is not less than 37 W / (m•K) at 500℃.

13. A magnesium alloy vacuum die-casting equipment, characterized in that, The invention includes a pressure chamber, a vacuum system, a protective gas supply system, a cooling gas supply system, and a die-casting punch as described in any one of claims 1-12. The die-casting punch is disposed in the pressure chamber, the pressure chamber has a vacuum hole, the vacuum system is connected to the vacuum hole, the protective gas supply system is connected to the protective gas inlet, and the cooling gas supply system is connected to the cooling gas inlet.

14. The magnesium alloy vacuum die-casting equipment according to claim 13, characterized in that, The magnesium alloy vacuum die-casting equipment includes a sealing element. An annular groove is formed on the outer peripheral surface of the die-casting punch. The radial inner end of the sealing element is accommodated in the annular groove. The sealing element is gas-tightly fitted with the inner wall of the pressure chamber. The protective vent is located on the outer surface of the die-casting punch closer to the side where the magnesium alloy liquid is located than the annular groove.

15. The magnesium alloy vacuum die-casting equipment according to claim 14, characterized in that, The sealing element is a composite structure made of a metal matrix and a rubber material.

Images