Aluminum alloy fitting casting metal mold

Abstract

The application belongs to the technical field of aluminum alloy casting, and particularly relates to a metal mold for aluminum alloy hardware casting, which comprises an upper mold base, a lower mold base, a cooling mechanism and a liquid changing mechanism. Through linkage and cooperation of the cooling unit and the liquid changing mechanism, the liquid cooling is sprayed through the liquid injection hole, and the temperature is uniformly extruded by the sealing plate, so that the temperature gradient of the traditional one-way water channel is eliminated, the mold cooling rate is consistent, the casting defects are effectively improved, the cooling efficiency is improved, the intelligent manufacturing production line demand is adapted, the automatic and rapid discharge of the heated cooling liquid is realized through the liquid changing column and the liquid changing pipe in the liquid changing mechanism, the through hole is arranged around the liquid injection hole, the heated cooling liquid is discharged quickly nearby, the contact time of the heated cooling liquid with the low-temperature cooling liquid is shortened, the automatic and rapid replacement of the heated cooling liquid is realized, the continuous supply of the low-temperature cooling liquid is ensured, the cooling stability is further improved, and the intelligent manufacturing efficient production is facilitated.

Description

Technical Field

[0001] This invention belongs to the field of aluminum alloy casting technology, specifically a metal mold for casting aluminum alloy fittings. Background Technology

[0002] Aluminum alloy fittings, as key components in power transmission, mechanical connections, and structural assembly, are characterized by their light weight, moderate strength, excellent electrical and thermal conductivity, and good corrosion resistance. They are widely used in power transmission and transformation lines, power distribution equipment, and mechanical structural connectors. With the rapid development of intelligent manufacturing and precision manufacturing, the mass production of aluminum alloy fittings has placed higher demands on forming accuracy, production efficiency, and process stability. Currently, most production methods adopt metal mold casting processes. The core process usually includes mold preheating, quantitative pouring of molten aluminum alloy, cavity pressure forming, forced cooling with circulating coolant, and mold opening and part removal. Metal molds have become the mainstream equipment for aluminum alloy fitting casting due to their advantages such as fast heat conduction, high forming accuracy, and long service life. The cooling process directly determines the internal density, dimensional accuracy, surface quality, and production efficiency of the fittings, making it a key control link in the casting process.

[0003] Existing molds generally have cooling water channels inside the mold body, and circulating coolant is introduced through an external cooling system to achieve rapid and uniform cooling of the cavity and molded parts, so as to shorten the molding cycle and improve product consistency, and adapt to the continuous and efficient production needs of intelligent manufacturing production lines.

[0004] However, current mold internal coolant channels mostly adopt a unidirectional straight-through arrangement. The coolant flows in from the inlet and then flows along a single path to the outlet. During the continuous flow and heat exchange process, the temperature gradually increases, causing the cooling capacity along the channel to continuously decrease. The cooling intensity is high in the inlet area, while the cooling effect in the outlet area is significantly reduced. This results in uneven temperature distribution in the mold cavity and significant differences in cooling rates in different parts of the molded part. Uneven cooling can easily cause defects such as internal stress, deformation, shrinkage cavities, and porosity in aluminum alloy fittings, seriously affecting the dimensional accuracy and mechanical properties of the fittings. At the same time, the heat exchange efficiency of unidirectional channels is limited. To ensure the cooling effect, the overall cooling time needs to be extended, which reduces the production cycle and capacity, making it difficult to match the requirements of intelligent manufacturing for efficient, stable, and controllable production. In addition, local overheating areas can accelerate thermal fatigue loss on the mold cavity surface, causing mold thermal deformation and surface cracking, shortening the mold's service life, and increasing production costs and maintenance frequency.

[0005] In view of this, in order to solve the above-mentioned technical problems, the present invention provides a metal mold for casting aluminum alloy fittings. Summary of the Invention

[0006] The present invention provides a metal mold for casting aluminum alloy fittings, including an upper mold base and a lower mold base. The upper mold base has a casting port and a cooling mechanism installed below the lower mold base. The cooling mechanism includes a liquid inlet unit and a cooling unit. A liquid exchange mechanism is provided below the lower mold base and is connected to the cooling mechanism. The liquid exchange mechanism includes a first liquid exchange unit and a second liquid exchange unit.

[0007] Preferably, the liquid inlet unit includes a cooling cavity formed at the bottom of the lower mold base, and a liquid inlet hole is formed on the lower mold base and at the bottom of the cooling cavity. A liquid inlet pipe is installed in the liquid inlet hole and is fixedly connected to the lower mold base. One end face of the liquid inlet pipe inside the cooling cavity is flush with the bottom surface of the cooling cavity.

[0008] Preferably, the cooling unit includes a sealing plate located inside the cooling chamber, which divides the cooling chamber into upper and lower parts. The sealing plate is slidably connected to the lower mold base. The sealing plate has multiple spray holes, each containing a one-way valve. Two hydraulic rods are symmetrically arranged below the sealing plate, with their output ends fixedly connected to the sealing plate. The hydraulic cylinders of the hydraulic rods are fixedly connected to the lower mold base.

[0009] Preferably, a sealing ring is fitted on the outer surface of the sealing plate.

[0010] Preferably, the first fluid changing unit includes multiple through holes formed on the sealing plate. A countersunk hole is formed on the side of the sealing plate near the upper mold base at each through hole. The countersunk hole is coaxially connected to the through hole. A connecting ring is provided inside the countersunk hole. A fluid changing pipe is fixedly connected below the connecting ring and passes through the through hole. The fluid changing pipe is slidably connected to the sealing plate. A limiting ring is provided inside the fluid changing pipe at the end of the fluid changing pipe near the upper mold base. The limiting ring is fixedly connected to the fluid changing pipe. A fluid changing column is provided inside the limiting ring and slidably connected to the limiting ring. A fluid changing chamber is formed inside the fluid changing column. A cross groove is formed at the top of the fluid changing column. A first fluid changing hole is formed at the center intersection of the cross groove and is connected to the fluid changing chamber.

[0011] Preferably, the second fluid changing unit includes a second fluid changing hole located on the fluid changing column and at the bottom of the fluid changing chamber. In the initial state, the fluid changing column is in contact with the limiting ring, and the horizontal height of the second fluid changing hole is higher than the bottom surface of the limiting ring. During operation, the horizontal height of the second fluid changing hole is lower than the bottom surface of the limiting ring. A support ring is provided below the fluid changing column, and the support ring is fixedly connected to the fluid changing pipe. A spring is fixedly connected between the support ring and the fluid changing column. A first notch is provided at the top of the limiting ring, and a second notch is provided at the top of the connecting ring. The first and second notches are adapted to the shape and position of the cross groove. A liquid collection chamber is provided below the lower mold base, and the bottom of the fluid changing pipe is located in the liquid collection chamber. A push plate is provided in the liquid collection chamber, and the push plate is slidably connected to the liquid collection chamber. The fluid changing pipe passes through the push plate and is fixedly connected to the push plate. A second hydraulic rod is symmetrically provided below the push plate, and the hydraulic cylinder of the second hydraulic rod is fixedly connected to the liquid collection chamber.

[0012] Preferably, all of the through holes are located close to the spray hole.

[0013] Preferably, a drain pipe is installed at the bottom of the liquid collection tank, and the liquid collection tank is fixed to the lower mold base by locking bolts.

[0014] Preferably, both the No. 1 and No. 2 fluid exchange holes are configured as oblique holes.

[0015] Preferably, the extension speed of the second hydraulic rod is greater than the extension speed of the first hydraulic rod.

[0016] The beneficial effects of this invention are as follows: 1. This invention utilizes the linkage between the cooling unit and the liquid exchange mechanism, employing a technology that sprays coolant through injection holes and uses sealing plates to compress and equalize the temperature. This eliminates the temperature gradient of traditional unidirectional water channels, ensuring a consistent cooling rate for the mold, effectively improving casting defects, while simultaneously increasing cooling efficiency and shortening the molding cycle, thus meeting the needs of intelligent manufacturing production lines.

[0017] 2. This invention relies on the linkage control of the fluid exchange unit and the cooling unit. Through structures such as the fluid exchange column and fluid exchange pipe, the heated coolant is automatically and quickly discharged. The through holes are set around the spray holes, allowing the heated coolant to be discharged quickly nearby, shortening its contact time with the low-temperature coolant, realizing the automatic and rapid replacement of the heated coolant, ensuring the continuous supply of low-temperature coolant, further improving cooling stability, and contributing to efficient production in intelligent manufacturing.

[0018] 3. The cooling and fluid exchange actions of this invention are automatically completed by the controller linking the hydraulic rod, without the need for manual intervention. It is suitable for intelligent manufacturing production lines and improves production stability. The liquid collection tank is designed to be detachable, which facilitates maintenance and reduces the cost of use. At the same time, the one-way valve and the inclined hole structure ensure the cooling and fluid exchange effect. Attached Figure Description

[0019] To make the content of this invention easier to understand, the invention will be further described in detail below with reference to specific embodiments and accompanying drawings.

[0020] Figure 1 This is a schematic diagram of the overall appearance and structure of the present invention; Figure 2 This is a schematic diagram of the internal structure of the lower mold base of the present invention; Figure 3 This is a bottom view of the internal structure of the lower mold base of the present invention; Figure 4 This is a front view of the lower mold base structure of the present invention; Figure 5 This is a schematic diagram of the upper structure of the sealing plate of the present invention; Figure 6 For the present invention Figure 5 Enlarged view of point A in the middle; Figure 7 This is a top view of the sealing plate structure of the present invention; Figure 8 This is a schematic diagram of the internal structure of the fluid exchange tube of the present invention; Figure 9 For the present invention Figure 8 Enlarged view at point B in the middle; Figure 10 This is a frontal cross-sectional view of the countersunk hole structure of the present invention; Figure 11 For the present invention Figure 10 Enlarged view at point C; In the diagram: 1. Upper mold base; 2. Lower mold base; 3. Casting gate; 4. Cooling mechanism; 41. Liquid inlet unit; 411. Cooling chamber; 412. Liquid inlet hole; 413. Liquid inlet pipe; 42. Cooling unit; 421. Sealing plate; 422. Spray hole; 423. Check valve; 424. No. 1 hydraulic rod; 5. Fluid changing mechanism; 51. No. 1 fluid changing unit; 511. Through hole; 512. Countersunk hole; 513. Connecting ring; 514. Fluid changing pipe; 515. Limiting ring; 516. Fluid changing column; 517. Fluid changing chamber; 518. Cross groove; 519. Fluid changing hole No. 1; 52. Fluid changing unit No. 2; 521. Fluid changing hole No. 2; 522. Support ring; 523. Spring; 524. Notch No. 1; 525. Notch No. 2; 526. Collection tank; 527. Push plate; 528. Hydraulic rod No. 2; 6. Sealing ring; 7. Locking bolt. Detailed Implementation

[0021] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0022] This invention provides a metal mold for casting aluminum alloy fittings, including an upper mold base 1 and a lower mold base 2. The upper mold base 1 has a casting port 3 and a cooling mechanism 4 installed below the lower mold base 2. The cooling mechanism 4 includes a liquid inlet unit 41 and a cooling unit 42. The liquid inlet unit 41 is used to transport coolant, and the cooling unit 42 is used to effectively improve the cooling uniformity of the casting while cooling it. A liquid exchange mechanism 5 is provided below the lower mold base 2 and is connected to the cooling mechanism 4. The liquid exchange mechanism 5 includes a first liquid exchange unit 51 and a second liquid exchange unit 52. The liquid exchange mechanism 5 is used to automatically and quickly discharge the heated coolant and cooperates with the cooling mechanism 4 to continuously supply low-temperature coolant to the casting, effectively improving cooling efficiency and ensuring uniform cooling of the casting.

[0023] The liquid inlet unit 41 includes a cooling cavity 411 opened at the bottom of the lower mold base 2. A liquid inlet hole 412 is opened on the lower mold base 2 at the bottom of the cooling cavity 411. A liquid inlet pipe 413 is installed in the liquid inlet hole 412. The liquid inlet pipe 413 is fixedly connected to the lower mold base 2. One end face of the liquid inlet pipe 413 inside the cooling cavity 411 is flush with the bottom surface of the cooling cavity 411.

[0024] The cooling unit 42 includes a sealing plate 421, which is located inside the cooling chamber 411. The sealing plate 421 divides the cooling chamber 411 into upper and lower parts. The upper part is a cooling space and the lower part is a liquid storage space. A sealing ring 6 is fitted on the outer surface of the sealing plate 421 to achieve a sliding sealing connection between the sealing plate 421 and the lower mold base 2. Multiple spray holes 422 are opened on the sealing plate 421. A one-way valve 423 is installed in the spray hole 422. Two first hydraulic rods 424 are symmetrically arranged below the sealing plate 421. The output ends of the two first hydraulic rods 424 are fixedly connected to the sealing plate 421. The hydraulic cylinder of the first hydraulic rod 424 is fixedly connected to the lower mold base 2. The first hydraulic rod 424 is controlled by a controller.

[0025] When manufacturing aluminum alloy hardware castings, the upper mold base 1 and the lower mold base 2 are first closed and fitted together to form a cavity between them. Then, a locking device is used to fix the upper mold base 1 and the lower mold base 2. Then, the molten metal is poured into the cavity from the casting port 3. After the molten metal completely fills the cavity, it is left to cool down to form the casting.

[0026] During the cooling process, the pump body is first connected to the pipeline and the inlet pipe 413. Then, under the action of the pump body, the coolant enters the storage space of the cooling chamber 411 through the inlet pipe 413. That is, in the initial state, the coolant is located below the sealing plate 421. When the storage space is full of coolant, the controller controls the output end of the first hydraulic rod 424 to retract. The retraction of the output end of the first hydraulic rod 424 drives the sealing plate 421 to move down. The downward movement of the sealing plate 421 squeezes the coolant below it. After being squeezed, the coolant is sprayed out from the spray hole 422 and sprayed towards the casting. In the liquid storage space, because a one-way valve 423 is installed in the spray hole 422, the coolant above the sealing plate 421 will not flow back into the liquid storage space below the sealing plate 421. During this process, the coolant is sprayed evenly on the bottom surface of the lower mold base 2 in a spray pattern. Compared with the heat exchange cooling method of the one-way water channel, the sprayed coolant can contact the bottom surface of the lower mold base 2 evenly at a lower temperature. After contact, it falls immediately due to gravity and gathers above the sealing plate 421, avoiding the coolant from heating up and reducing the cooling effect after prolonged contact with the heat source.

[0027] After the sealing plate 421 moves down to fit against the bottom of the cooling cavity 411, the controller again controls the output end of the first hydraulic rod 424 to extend upward, pushing the sealing plate 421 upward. As the sealing plate 421 moves upward, it gradually squeezes the coolant above the sealing plate 421 to fit against the top of the cooling cavity 411, so that the coolant is in complete contact with the top of the cooling cavity 411. That is, the coolant is in full contact with the heat source under a uniform overall temperature, avoiding local cooling intensity differences caused by the cooling liquid heating up along the pipe. This achieves uniform and synchronous cooling of the mold cavity and the molded part. Compared with the existing unidirectional flow cooling channel, this structure can effectively eliminate the temperature gradient of the coolant flowing along the pipe, so that the cooling rate of each area of ​​the mold tends to be uniform, significantly improving defects such as internal stress, deformation, shrinkage, and porosity of the hardware caused by uneven cooling. At the same time, it improves cooling efficiency, shortens the molding cycle, and better meets the requirements of intelligent manufacturing production lines for molding quality and production stability.

[0028] The first fluid changing unit 51 includes multiple through holes 511 formed on the sealing plate 421. A countersunk hole 512 is formed on the side of the sealing plate 421 near the upper mold base 1 at each through hole 511. The countersunk hole 512 is coaxially connected to the through hole 511. A connecting ring 513 is provided inside the countersunk hole 512. A fluid changing pipe 514 is fixedly connected below the connecting ring 513. The fluid changing pipe 514 passes through the through hole 511 and fits against the wall of the through hole 511. The fluid changing pipe 514 is connected to the sealing plate 421. The liquid exchange pipe 514 is slidably connected to the upper mold base 1. A limiting ring 515 is provided inside the liquid exchange pipe 514. The limiting ring 515 is fixedly connected to the liquid exchange pipe 514. A liquid exchange column 516 is provided inside the limiting ring 515. The liquid exchange column 516 is slidably connected to the limiting ring 515. A liquid exchange cavity 517 is opened inside the liquid exchange column 516. A cross groove 518 is opened at the top of the liquid exchange column 516. A first liquid exchange hole 519 is opened at the center intersection of the cross groove 518. The first liquid exchange hole 519 is connected to the liquid exchange cavity 517.

[0029] The second fluid exchange unit 52 includes a second fluid exchange hole 521 located on the fluid exchange column 516 and at the bottom of the fluid exchange chamber 517. Initially, the fluid exchange column 516 is in contact with the limiting ring 515, and the horizontal height of the second fluid exchange hole 521 is higher than the bottom surface of the limiting ring 515, thus sealing the second fluid exchange hole 521. During operation, the horizontal height of the second fluid exchange hole 521 is lower than the bottom surface of the limiting ring 515, allowing the second fluid exchange hole 521 to flow. A support ring 522 is located below the fluid exchange column 516 and is fixedly connected to the fluid exchange pipe 514. A spring 523 is fixedly connected between the support ring 522 and the fluid exchange column 516, and a pressure sensor is mounted on the spring 523. A notch 524 is provided at the top of the limiting ring 515. The top of the connecting ring 513 has a second notch 525. The first notch 524 and the second notch 525 are adapted to the shape and position of the cross groove 518. A liquid collection chamber 526 is provided below the lower mold base 2. The bottom of the liquid exchange pipe 514 is located in the liquid collection chamber 526. A push plate 527 is provided in the liquid collection chamber 526. The push plate 527 is slidably connected to the liquid collection chamber 526. The liquid exchange pipe 514 passes through the push plate 527 and is fixedly connected to the push plate 527. A second hydraulic rod 528 is symmetrically arranged below the push plate 527. The output end of the second hydraulic rod 528 does not contact the push plate 527 in the initial state. The hydraulic cylinder of the second hydraulic rod 528 is fixedly connected to the liquid collection chamber 526. The extension speed of the second hydraulic rod 528 is greater than the extension speed of the first hydraulic rod 424.

[0030] When the output end of hydraulic rod 424 moves upward, the controller simultaneously controls the output end of hydraulic rod 528 to extend. Hydraulic rod 424 moves the sealing plate 421 upward. The upward movement of the sealing plate 421, through the countersunk hole 512 and the connecting ring 513, moves the fluid exchange pipe 514 upward. The upward movement of the fluid exchange pipe 514 moves the push plate 527 upward. Since the extension speed of hydraulic rod 528 is greater than that of hydraulic rod 424, when the output end of hydraulic rod 528 contacts the push plate 527 and continues to push the push plate 527, the push plate 527 moves the fluid exchange pipe 514 upward along the through hole 511. As the fluid exchange pipe 514 moves upward, the top of the fluid exchange column 516 first contacts the top of the cooling chamber 411, and then the hydraulic rod 428 moves upward. As the output end of the pressure rod 528 continues to extend, the fluid exchange column 516 is compressed, the spring 523 deforms, and the fluid exchange column 516 moves down along the limiting ring 515. When the second fluid exchange hole 521 at the bottom of the fluid exchange column 516 is below the limiting ring 515, the top of the fluid exchange column 516 is flush with the connecting ring 513, that is, the top of the connecting ring 513 also contacts the top of the cooling chamber 411. At the same time, the compressive force on the spring 523 reaches the specified value, and the pressure sensor installed on the spring 523 transmits the signal to the controller. The controller controls the output end of the second hydraulic rod 528 to stop extending. At this time, the second fluid exchange hole 521 is in a flowing state. Meanwhile, as the sealing plate 421 moves upward, it squeezes the coolant above the sealing plate 421 to fit against the top of the cooling chamber 411. As a result, the coolant temperature is higher closer to the top of the cooling chamber 411. At this time, the top of the exchange column 516 and the top of the connecting ring 513 are in contact with the top of the cooling chamber 411. The coolant with higher temperature enters the exchange chamber 517 from the second notch 525 of the connecting ring 513, the first notch 524 at the top of the limiting ring 515, the cross groove 518 at the top of the exchange column 516 and the first exchange hole 519 in sequence. Then it flows out through the second exchange hole 521 and falls into the collection tank 526 through the exchange pipe 514. Meanwhile, the sealing plate 421 continues to move upward, gradually squeezing the coolant at a lower temperature until it comes into contact with the heat source, until the sealing plate 421 is in contact with the upper surface of the cooling chamber 411. This allows all the heated coolant in the cooling chamber 411 to be squeezed into the fluid exchange chamber 517, and then enters the collection tank 526 through the second fluid exchange hole 521. This allows the invention to effectively improve uniform heat dissipation, ensure uniform casting temperature, reduce temperature gradients in different areas of the casting, and automatically and quickly discharge the heated coolant, further improving the gradual cooling efficiency. After the coolant in the cooling space is discharged, the controller controls the output ends of hydraulic rod 424 and hydraulic rod 528 to retract, and at the same time controls the pump to work. The pump delivers coolant into the storage space. The output ends of hydraulic rod 424 and hydraulic rod 528 retract, spring 523 returns to its original position, and the second fluid exchange hole 521 is sealed. At the same time, the sealing plate 421 moves down. When the sealing plate 421 moves down to contact the coolant below again, it continues to move down, squeezing the coolant again, so that the coolant is sprayed from the spray hole 422 onto the heat source again. This process is repeated to achieve continuous cooling and temperature reduction.

[0031] Multiple through holes 511 are arranged close to and around the spray hole 422, which allows the coolant sprayed from the spray hole 422 to come into contact with the heat source and heat up, and then enter the coolant exchange chamber 517 through the cross groove 518 as soon as possible, and then be discharged as soon as possible, shortening the contact time between the heated coolant and the unheated coolant, and ensuring the effective use of coolant.

[0032] A drain pipe is installed at the bottom of the liquid collection tank 526. The liquid collection tank 526 is fixed to the lower mold base 2 by locking bolts 7, which facilitates the disassembly of the liquid collection tank 526 and makes it easier to clean the liquid collection tank 526 later.

[0033] Both the No. 1 coolant exchange hole 519 and the No. 2 coolant exchange hole 521 are designed with an oblique hole structure to increase the flow rate of the coolant and reduce the amount of already heated coolant remaining in the cooling chamber 411.

[0034] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

Claims

1. A metal mold for casting aluminum alloy fittings, comprising an upper mold base (1) and a lower mold base (2), wherein the upper mold base (1) is provided with a casting gate (3), characterized in that, It also includes a cooling mechanism (4), which is installed below the lower mold base (2). The cooling mechanism (4) includes a liquid inlet unit (41) and a cooling unit (42). A liquid exchange mechanism (5) is provided below the lower mold base (2). The liquid exchange mechanism (5) is connected to the cooling mechanism (4). The liquid exchange mechanism (5) includes a first liquid exchange unit (51) and a second liquid exchange unit (52).

2. The metal mold for casting aluminum alloy fittings according to claim 1, characterized in that: The liquid inlet unit (41) includes a cooling cavity (411) opened at the bottom of the lower mold base (2). A liquid inlet hole (412) is opened on the lower mold base (2) and at the bottom of the cooling cavity (411). A liquid inlet pipe (413) is installed in the liquid inlet hole (412). The liquid inlet pipe (413) is fixedly connected to the lower mold base (2). One end face of the liquid inlet pipe (413) inside the cooling cavity (411) is flush with the bottom surface of the cooling cavity (411).

3. The metal mold for casting aluminum alloy fittings according to claim 2, characterized in that: The cooling unit (42) includes a sealing plate (421), which is located inside the cooling chamber (411). The sealing plate (421) divides the cooling chamber (411) into upper and lower parts. The sealing plate (421) is slidably connected to the lower mold base (2). The sealing plate (421) has multiple spray holes (422). A one-way valve (423) is installed in the spray holes (422). Two hydraulic rods (424) are symmetrically arranged below the sealing plate (421). The output ends of the two hydraulic rods (424) are fixedly connected to the sealing plate (421). The hydraulic cylinder of the hydraulic rod (424) is fixedly connected to the lower mold base (2).

4. The metal mold for casting aluminum alloy fittings according to claim 3, characterized in that: A sealing ring (6) is fitted on the outer surface of the sealing plate (421).

5. A metal mold for casting aluminum alloy fittings according to claim 3, characterized in that: The first fluid exchange unit (51) includes multiple through holes (511) on the sealing plate (421). A countersunk hole (512) is provided on the side of the sealing plate (421) near the upper mold base (1) at each through hole (511). The countersunk hole (512) is coaxially connected to the through hole (511). A connecting ring (513) is provided inside the countersunk hole (512). A fluid exchange pipe (514) is fixedly connected below the connecting ring (513). The fluid exchange pipe (514) passes through the through hole (511) and is slidably connected to the sealing plate (421). (514) is provided with a limiting ring (515), the limiting ring (515) is located at one end of the liquid exchange pipe (514) near the upper mold base (1), the limiting ring (515) is fixedly connected to the liquid exchange pipe (514), the limiting ring (515) is provided with a liquid exchange column (516), the liquid exchange column (516) is slidably connected to the limiting ring (515), the liquid exchange column (516) is provided with a liquid exchange chamber (517), the top of the liquid exchange column (516) is provided with a cross groove (518), the center intersection of the cross groove (518) is provided with a first liquid exchange hole (519), the first liquid exchange hole (519) is connected to the liquid exchange chamber (517).

6. The metal mold for casting aluminum alloy fittings according to claim 5, characterized in that: The second fluid exchange unit (52) includes a second fluid exchange hole (521) located on the fluid exchange column (516) and at the bottom of the fluid exchange chamber (517). In the initial state, the fluid exchange column (516) is in contact with the limiting ring (515), and the horizontal height of the second fluid exchange hole (521) is higher than the bottom surface of the limiting ring (515). During operation, the horizontal height of the second fluid exchange hole (521) is lower than the bottom surface of the limiting ring (515). A support ring (522) is provided below the fluid exchange column (516). The support ring (522) is fixedly connected to the fluid exchange tube (514). A spring (523) is fixedly connected between the support ring (522) and the fluid exchange column (516). A notch (5) is provided at the top of the limiting ring (515). 24) The top of the connecting ring (513) is provided with a second notch (525). The first notch (524) and the second notch (525) are adapted to the shape and position of the cross groove (518). A liquid collection chamber (526) is provided below the lower mold base (2). The bottom of the liquid exchange pipe (514) is located in the liquid collection chamber (526). A push plate (527) is provided in the liquid collection chamber (526). The push plate (527) is slidably connected to the liquid collection chamber (526). The liquid exchange pipe (514) passes through the push plate (527) and is fixedly connected to the push plate (527). A second hydraulic rod (528) is symmetrically arranged below the push plate (527). The hydraulic cylinder of the second hydraulic rod (528) is fixedly connected to the liquid collection chamber (526).

7. A metal mold for casting aluminum alloy fittings according to claim 5, characterized in that: The multiple through holes (511) are all located close to the spray hole (422).

8. A metal mold for casting aluminum alloy fittings according to claim 6, characterized in that: The liquid collection chamber (526) is equipped with a drain pipe at the bottom, and the liquid collection chamber (526) is fixed to the lower mold base (2) by locking bolts (7).

9. A metal mold for casting aluminum alloy fittings according to claim 6, characterized in that: Both the No. 1 fluid exchange hole (519) and the No. 2 fluid exchange hole (521) are configured as oblique holes.

10. A metal mold for casting aluminum alloy fittings according to claim 6, characterized in that: The extension speed of the second hydraulic rod (528) is greater than that of the first hydraulic rod (424).

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