Directional solidification casting apparatus for low internal stress aluminum alloy complex structure

Abstract

The application relates to the technical field of metal casting, and discloses a directional solidification casting equipment for low-internal-stress aluminum alloy complex structures, which comprises a heat preservation furnace, a rotary casting assembly, an infiltration temperature control assembly and a forming die. The casting equipment is provided with the rotary casting assembly and the forming die on a rotary table, the rotary table rotates at different rotating speeds to provide controllable centrifugal force, metal liquid is infiltrated and cast on the forming die in the anti-gravity mode under the action of the centrifugal force, the infiltration speed and pressure can be adjusted by changing the centrifugal force, the limitation of workpiece size in negative pressure casting is broken, and the anti-gravity casting of complex structure workpieces is facilitated, the equipment can simultaneously synchronously cast multiple molds, each process parameter is convenient to uniformly control, the quality consistency is ensured, the problem that continuous carbon fiber reinforced aluminum matrix composite materials are difficult to mass produce is solved, and the production efficiency is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of metal casting, in particular to a directional solidification casting equipment for low internal stress aluminum alloy complex structure. BACKGROUND

[0002] In the fields of aerospace, automobile industry and high-end equipment manufacturing, higher requirements are put forward for the manufacturing of aluminum alloy complex structure parts. Such parts not only need to have mechanical properties such as high strength and good ductility, but also have very high requirements for dimensional stability and internal stress level. Too high internal stress is easy to cause subsequent processing deformation, cracking and product service failure, thereby affecting the manufacturing quality and service life.

[0003] In the prior art, a patent document with publication number CN110976805B discloses a complex structure aluminum alloy counter-gravity casting forming method, which solves the problem that automobile sub-frame type aluminum alloy castings with uneven thickness are not suitable for adopting cold iron heat absorption process measures.

[0004] The continuous carbon fiber reinforced aluminum matrix composite material proposed in the prior art has excellent properties such as light weight, high specific strength, high specific stiffness, good wear resistance and good high temperature performance, and has attracted much attention from the aerospace and national defense industry. It has become one of the most strategic structural materials in the field of modern national defense industry. Currently, vacuum air pressure infiltration is the main method for near-net forming of Cf / Al composite materials. See reference: Yao Jing. Microstructure and mechanical properties of Cf / Al composite materials prepared by different matrix alloys [D]. Nanchang Hangkong University, 2014.

[0005] Counter-gravity casting and vacuum air pressure infiltration casting both use external driving force (such as air pressure, vacuum, etc.) to make the metal liquid flow in the opposite direction of gravity and crystallize and solidify under pressure. However, vacuum air pressure infiltration casting is suitable for laboratory environment, and the size of the workpiece prepared is limited, the production efficiency is low, and it cannot meet the requirements of industrial production. In the preparation process of continuous carbon fiber reinforced aluminum matrix composite material, the existing counter-gravity casting device has the problems of inconvenient control of infiltration process and directional solidification, which affects the mechanical properties of the material. SUMMARY

[0006] The purpose of the present application is to solve the problem of inconvenient control of infiltration process and directional solidification of the existing counter-gravity casting device in the preparation process of continuous carbon fiber reinforced aluminum matrix composite material in the prior art, and to propose a directional solidification casting equipment for low internal stress aluminum alloy complex structure.

[0007] In order to achieve the above-mentioned purpose, the present application adopts the following technical scheme: a directional solidification casting equipment for low internal stress aluminum alloy complex structure, comprising:

[0008] The inner cavity bottom of the holding furnace is rotatably provided with a rotating table, and the bottom of the holding furnace is fixedly provided with a speed reducer motor, which drives the rotating table to rotate, the inside of the holding furnace is fixedly provided with a heat insulation cover, the heat insulation cover divides the upper side space of the rotating table into an inner cavity and an outer cavity, the top of the holding furnace is fixedly provided with a casting pipe, and the bottom end of the casting pipe extends into the inner cavity;

[0009] The rotating casting assembly comprises a transfer bin and a flow guide pipe, the transfer bin is fixedly installed at the upper surface shaft center of the rotating table, the bottom end of the casting pipe extends into the upper opening of the transfer bin, a plurality of flow guide pipes are fixedly connected with the bottom end of the transfer bin, and each flow guide pipe is in communication with the inner cavity of the transfer bin;

[0010] The infiltration temperature control assembly comprises a first electric heating pipe and a second electric heating pipe, the first electric heating pipe is fixedly installed on the inner side of the heat insulation cover, a plurality of independent second electric heating pipes are arranged in layers in the vertical direction, at least three layers are independently controlled in temperature, and are fixedly installed on the inner wall of the outer cavity;

[0011] The surface of the forming mold is provided with a vent pipe in communication with the inner cavity of the forming mold, a plurality of forming molds are detachably fixedly installed on the surface of the rotating table, and the plurality of forming molds are arranged in an annular array in the outer cavity, and the end of the flow guide pipe away from the transfer bin is in communication with the inner cavity of the forming mold.

[0012] The device can simultaneously perform synchronous casting on multiple molds in an anti-gravity manner, the process parameters are easy to control uniformly, the quality consistency is ensured, the problem that the preparation of continuous carbon fiber reinforced aluminum matrix composite materials is difficult to mass produce is solved, and the production efficiency is improved.

[0013] Preferably, the forming mold comprises a mold base and a mold shell, the mold shell is fixedly installed on the upper side of the mold base, the inside of the mold base is provided with a lower storage cavity, the inside of the mold shell is provided with a forming cavity and an upper storage cavity, the mold base is in plug-in connection with the end of the flow guide pipe, the flow guide pipe is in communication with the forming cavity through the lower storage cavity, the forming cavity is in communication with the vent pipe through the upper storage cavity, and air in the mold is discharged through the vent pipe during gas washing.

[0014] Preferably, the inside of the mold shell is provided with a compensation channel, the upper and lower ends of the compensation channel are in communication with the upper storage cavity and the lower storage cavity respectively, the compensation channel is in communication with the forming cavity through a plurality of branch channels; the lower storage cavity is slidably provided with a blocking block, the surface of the mold base is slidably provided with a transmission seat, the end of the transmission seat is fixedly connected with the blocking block, the inside of the holding furnace is fixedly provided with a pneumatic impact hammer, the telescopic end of the pneumatic impact hammer faces the transmission seat, and the action of the blocking block is controlled through the pneumatic impact hammer.

[0015] Preferably, the bottom of the holding furnace is provided with an angle sensor, the rotation angle of the rotating table is detected through the angle sensor, when the telescopic end of the pneumatic impact hammer is aligned with any transmission seat, the impact transmission seat of the pneumatic impact hammer switches the plugging block from the state of plugging the lower end of the compensation channel to the state of plugging the lower end of the forming cavity, preventing the backflow of the filling material in the forming cavity.

[0016] Preferably, the bottom end of the casting pipe is fixedly installed with an annular air cover, the annular air cover covers the gap between the casting pipe and the transfer bin, the upper side of the holding furnace is fixedly installed with an inert gas supply pipe in communication with the annular air cover, and after the upper end of the casting pipe is plugged, the inert gas is introduced into the transfer bin from the annular air cover, and the main function is to wash the transfer bin to reduce the oxygen content.

[0017] Preferably, the holding furnace comprises a furnace base and a furnace body, the furnace body is fixedly installed on the upper side of the furnace base, and a circulating cooling pipe is embedded in the furnace body; an input air pipe and an output air pipe are fixedly installed on the surface of the furnace body, the output air pipe is in communication with the outer chamber, and the input air pipe is in communication with the lower side space of the rotating table, a plurality of holes penetrating up and down are formed in the surface of the rotating table; an operation window is formed in the surface of the furnace body, and a sealing door is hingedly installed on the mouth of the operation window.

[0018] The present application has the following advantages:

[0019] 1. The casting equipment provided by the present application provides controllable centrifugal force by rotating the rotating table at different speeds, the metal liquid is infiltrated and cast on the forming mold in the manner of anti-gravity under the action of the centrifugal force, the infiltration speed and pressure can be adjusted by changing the size of the centrifugal force, and the size limitation of the workpiece in the negative pressure casting is eliminated, thereby providing convenience for anti-gravity casting of complex structure workpieces, the equipment can simultaneously cast multiple molds synchronously, each process parameter is easy to control uniformly, the quality consistency is ensured, the problem that continuous carbon fiber reinforced aluminum matrix composites are difficult to mass produce is solved, and the production efficiency is improved.

[0020] 2. The casting equipment provided by the present application is provided with an infiltration temperature control assembly in the inner and outer chambers of the holding furnace, the transfer bin is preheated through the first electric heating pipe to ensure controllable casting temperature, the forming mold and the fiber in the mold are preheated through the second electric heating pipe to prevent the aluminum liquid from being rapidly chilled and solidified by the carbon fiber, improve the flowability of the aluminum liquid, reduce the viscous resistance, improve the wettability of the aluminum liquid and the carbon fiber and reduce the surface energy of the aluminum liquid, the aluminum liquid can better infiltrate into the fiber gap and solidify, and the residual stress in the matrix is reduced, since the second electric heating pipe is arranged in layers and is cooled in a certain temperature gradient from bottom to top, the bottom end of the forming mold is preferentially cooled and the upper end is lastly cooled, the clear sequential solidification path is realized, directional solidification is realized, the aluminum liquid is ensured to be fully infiltrated and filled, hole defects are reduced, and stress concentration is reduced.

[0021] 3. The casting equipment proposed in this invention has an upper storage cavity within the forming mold. The molten aluminum in the upper storage cavity undergoes delayed solidification, maintaining unobstructed feeding and providing pressure assistance to the filling liquid in the forming cavity and compensation channel. This enhances the filling and feeding capabilities of complex thin-walled and long-channel structures, preventing defects in the composite material. It should be noted that the pressure assistance provided by the molten aluminum in the upper storage cavity to the forming cavity can be adjusted by changing the rotation speed of the rotary table. Increasing the rotation speed of the rotary table decreases the pressure assistance, while decreasing the rotation speed increases the pressure assistance. This prevents excessive pressure assistance at different solidification time periods from causing residual stress in the composite material and affecting its performance.

[0022] 4. The casting equipment proposed in this invention has a sealing block installed in the lower storage cavity of the forming mold. The sealing block is driven by a pneumatic impact hammer to seal the bottom of the forming cavity, thereby preventing the aluminum liquid from flowing back. Under the centrifugal force of the rotating table, the aluminum liquid in the transfer chamber and the guide pipe is discharged into the lower storage cavity, and the aluminum liquid in the guide pipe is emptied to prevent blockage, so as to be reused and meet the requirements of mass production. Attached Figure Description

[0023] Figure 1 This is a three-dimensional structural diagram of the casting equipment proposed in this invention;

[0024] Figure 2 This is a three-dimensional structural diagram of the rotary table proposed in this invention;

[0025] Figure 3 This is a schematic diagram of the front section structure of the casting equipment proposed in this invention;

[0026] Figure 4 This is a schematic diagram (a) of the orthographic structure of the molding die proposed in this invention.

[0027] Figure 5 This is a schematic diagram (II) of the orthographic structure of the molding die proposed in this invention;

[0028] Figure 6 This is a schematic diagram (III) of the orthographic structure of the molding die proposed in this invention.

[0029] In the diagram: 1. Insulation furnace, 2. Rotary table, 3. Gear motor, 4. Inner chamber, 5. Outer chamber, 6. Casting pipe, 7. Transfer chamber, 8. Guide pipe, 9. First electric heating tube, 10. Second electric heating tube, 11. Insulation cover, 12. Molding mold, 13. Mold base, 14. Mold shell, 15. Lower storage cavity, 16. Upper storage cavity, 17. Compensation channel, 18. Sealing block, 19. Transmission seat, 20. Pneumatic impact hammer, 21. Angle sensor, 22. Annular air hood, 23. Furnace base, 24. Furnace body, 25. Input air duct, 26. Output air duct, 27. Hole, 28. Sealing door, 29. Vent pipe, 30. Molding cavity. Detailed Implementation

[0030] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0031] In the description of this invention, it should be understood that the terms "upper", "lower", "front", "rear", "left", "right", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0032] Reference Figures 1-6 A directional solidification casting device for complex structures of low internal stress aluminum alloys includes: a holding furnace 1, a rotary casting assembly, an impregnation temperature control assembly, and a forming mold 12.

[0033] Among them, heat preservation furnace 1, such as Figure 1 As shown, the heat preservation furnace 1 includes a furnace base 23 and a furnace body 24. The furnace body 24 is fixedly installed on the upper side of the furnace base 23. An operation window is opened on the surface of the furnace body 24, and a sealing door 28 is hinged to the opening of the operation window. A rotating table 2 is rotatably installed at the bottom of the inner cavity of the heat preservation furnace 1. A geared motor 3 is fixedly installed at the bottom of the heat preservation furnace 1. The rotating table 2 is driven to rotate by the geared motor 3. A circulating cooling pipe is embedded inside the furnace body 24. Cooling liquid is introduced into the circulating cooling pipe from bottom to top for cooling the furnace body 24.

[0034] like Figure 3 As shown, an inlet air duct 25 and an outlet air duct 26 are fixedly installed on the surface of the furnace body 24. The outlet air duct 26 is connected to the outer chamber 5, and the inlet air duct 25 is connected to the lower space of the rotary table 2. Several through holes 27 are opened on the surface of the rotary table 2. Figure 2 After casting is completed, air is introduced into the furnace through the inlet air duct 25 and the outlet air duct 26 to assist in air cooling.

[0035] like Figure 3 As shown, a heat insulation cover 11 is fixedly installed inside the heat insulation furnace 1. The lower surface of the heat insulation cover 11 slides in contact with the protrusion on the rotating table 2. The heat insulation cover 11 divides the upper space of the rotating table 2 into an inner chamber 4 and an outer chamber 5. A casting pipe 6 is fixedly installed on the top of the heat insulation furnace 1. The bottom end of the casting pipe 6 extends into the inner chamber 4.

[0036] Rotary casting components, such as Figure 3As shown, including the transfer warehouse 7 and the guide pipe 8, the transfer warehouse 7 is fixedly installed at the upper surface of the rotating table 2, the bottom end of the casting pipe 6 extends into the upper opening of the transfer warehouse 7, a plurality of guide pipes 8 are fixedly connected with the bottom end of the transfer warehouse 7, and each guide pipe 8 is in communication with the inner cavity of the transfer warehouse 7, and the bottom end of the casting pipe 6 is fixedly installed with an annular gas cover 22, the annular gas cover 22 is wrapped in the gap between the casting pipe 6 and the transfer warehouse 7, and the upper side of the holding furnace 1 is fixedly installed with an inert gas supply pipe in communication with the annular gas cover 22, after blocking the upper end of the casting pipe 6, the inert gas is introduced into the transfer warehouse 7 from the annular gas cover 22, and the main function is to wash the transfer warehouse 7 and reduce the oxygen content.

[0037] The infiltration temperature control assembly, such as Figure 3 As shown, including the first electric heating pipe 9 and the second electric heating pipe 10, the first electric heating pipe 9 is fixedly installed on the inner side of the temperature insulation cover 11, a plurality of independent second electric heating pipes 10 are arranged in vertical direction in layers, at least three layers, each layer is independently temperature controlled, and is fixedly installed on the inner wall of the outer chamber 5.

[0038] The forming mold 12, such as Figure 2 As shown, the surface of the forming mold 12 is provided with a vent pipe 29 in communication with the inner cavity of the forming mold 12, a plurality of forming molds 12 are detachably fixedly installed on the surface of the rotating table 2, and a plurality of forming molds 12 are arranged in an annular array in the outer chamber 5, and the end of the guide pipe 8 away from the transfer warehouse 7 is in communication with the inner cavity of the forming mold 12;

[0039] Specifically, referring to Figure 4 、 Figure 5 、 Figure 6 , the forming mold 12 includes a mold base 13 and a mold shell 14, the mold shell 14 is fixedly installed on the upper side of the mold base 13, the inside of the mold base 13 is provided with a lower storage cavity 15, the inside of the mold shell 14 is provided with a forming cavity 30 and an upper storage cavity 16, the mold base 13 is in plug-in connection with the end of the guide pipe 8, the guide pipe 8 is in communication with the forming cavity 30 through the lower storage cavity 15, and the forming cavity 30 is in communication with the vent pipe 29 through the upper storage cavity 16;

[0040] The inside of the mold shell 14 is provided with a compensation channel 17, the upper and lower ends of the compensation channel 17 are in communication with the upper storage cavity 16 and the lower storage cavity 15 respectively, and the compensation channel 17 is in communication with the forming cavity 30 through a plurality of branch channels;

[0041] A sealing block 18 is slidingly installed in the lower cavity 15, the surface of the mold base 13 slidingly inserts a transmission seat 19, the end of the transmission seat 19 is fixedly connected with the sealing block 18, the inside of the holding furnace 1 is fixedly installed with a pneumatic impact hammer 20, the telescopic end of the pneumatic impact hammer 20 faces the transmission seat 19, the bottom of the holding furnace 1 is provided with an angle sensor 21, the rotation angle of the rotating table 2 is detected through the angle sensor 21, when the telescopic end of the pneumatic impact hammer 20 is aligned with any transmission seat 19, the impact of the pneumatic impact hammer 20 on the transmission seat 19 makes the sealing block 18 switch from the state of sealing the lower end of the compensation channel 17 to the state of sealing the lower end of the forming cavity 30, as shown in Figure 4 , as shown in Figure 6 , at this time, the aluminum liquid enters the lower cavity 15 from the bottom end of the compensation channel 17, and waits for the aluminum liquid to solidify to block the resetting of the sealing block 18.

[0042] The method for preparing carbon fiber reinforced aluminum matrix composite material by using the casting equipment:

[0043] 1. Selecting a low internal stress aluminum alloy matrix and pretreating: selecting a low internal stress aluminum alloy such as ZL301 or MIC-6, and preparing aluminum liquid by melting;

[0044] 2. Installation of the forming mold 12 and gas washing, installing a carbon fiber preform in the forming cavity 30 in the forming mold 12, installing the forming mold 12 on the rotating table 2, introducing nitrogen gas from the annular gas cover 22 into the transfer bin 7, entering the forming cavity 30 along the flow guide pipe 8, and finally discharging to the outer chamber 5 from the air pipe 29, as shown in Figure 4 , the nitrogen gas in the outer chamber 5 is recovered and treated from the input air pipe 25 and the output air pipe 26;

[0045] 3. Counter-gravity casting and infiltration of aluminum liquid, preheating the transfer bin 7 by the first electric heating pipe 9, preheating the forming mold 12 and the carbon fiber preform in the mold by the second electric heating pipe 10, as shown in Figure 5 , introducing the aluminum liquid into the transfer bin 7 from the casting pipe 6, starting the speed reducer motor 3 to drive the rotating table 2 to rotate, under the action of centrifugal force, the aluminum liquid enters the lower cavity 15, the forming cavity 30, the compensation channel 17 and the upper cavity 16 in turn through the flow guide pipe 8, as shown in Figure 6 , the aluminum liquid completes the counter-gravity filling and infiltration of the carbon fiber preform, and the infiltration process is described in the reference: Yao Jing. Microstructure and mechanical properties of C_f / Al composites prepared by different matrix alloys [D]. Nanchang Hangkong University, 2014;

[0046] 4. Directional solidification process control: The second heating element 10 cools from bottom to top according to a certain temperature gradient, so that the bottom of the molding mold 12 cools first and the top cools last. During this process, the pneumatic impact hammer 20 impacts the transmission seat 19, causing the sealing block 18 to switch from the state at the lower end of the sealing compensation channel 17 to the state at the lower end of the sealing molding cavity 30. Figure 6 As shown, at this time, under the centrifugal force of the rotating table 2, the aluminum liquid in the transfer chamber 7 and the guide pipe 8 is discharged into the lower storage chamber 15, and the aluminum liquid in the guide pipe 8 is emptied to prevent blockage so that it can be reused.

[0047] It should be noted that an upper storage cavity 16 is provided in the molding mold 12. The aluminum liquid in the upper storage cavity 16 is delayed in solidification to maintain smooth feeding and to provide pressure assistance to the filling liquid in the molding cavity 30 and the compensation channel 17. This is to improve the filling and feeding capacity of complex thin-walled and long flow channel structures and avoid defects in the composite material. The pressure assistance of the aluminum liquid in the upper storage cavity 16 to the molding cavity 30 can be adjusted by changing the rotation speed of the rotary table 2. Since the direction of this pressure assistance is vertical and perpendicular to the direction of the centrifugal force on the aluminum liquid, when the rotation speed of the rotary table 2 increases, the centrifugal force on the aluminum liquid in the upper storage cavity 16 increases, and its pressure assistance decreases. When the rotation speed of the rotary table 2 decreases, the centrifugal force on the aluminum liquid in the upper storage cavity 16 decreases, and its pressure assistance increases. This prevents the composite material from generating residual stress due to excessive pressure assistance at different solidification time periods, which would affect the performance of the composite material.

[0048] 5. Demolding: After removing the cast workpiece, the material located in the lower storage cavity 15, upper storage cavity 16, and compensation channel 17 needs to be removed, while the material in the molding cavity 30 is retained.

[0049] The casting equipment proposed in this invention uses a rotary casting assembly and a forming mold 12 mounted on a rotary table 2. The rotary table 2 rotates at different speeds to provide controllable centrifugal force. Under the action of this centrifugal force, the molten metal impregnates and casts the forming mold 12 in an anti-gravity manner. The impregnation speed and pressure can be adjusted by changing the magnitude of the centrifugal force, thus overcoming the limitation of workpiece size in negative pressure casting and providing convenience for casting complex structural workpieces using anti-gravity. This equipment can simultaneously cast multiple molds synchronously, and the process parameters can be easily controlled uniformly to ensure consistent quality. It solves the problem of difficulty in mass production of continuous carbon fiber reinforced aluminum matrix composites, thereby improving production efficiency.

[0050] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A directional solidification casting device for complex structures of low-internal-stress aluminum alloys, characterized in that, include: A heat preservation furnace (1) has a rotating platform (2) installed at the bottom of its inner cavity. A geared motor (3) is fixedly installed at the bottom of the heat preservation furnace (1). The rotating platform (2) is driven to rotate by the geared motor (3). A heat insulation cover (11) is fixedly installed inside the heat preservation furnace (1). The heat insulation cover (11) divides the upper space of the rotating platform (2) into an inner cavity (4) and an outer cavity (5). A casting pipe (6) is fixedly installed on the top of the heat preservation furnace (1). The bottom end of the casting pipe (6) extends into the inner cavity (4). The rotary casting assembly includes a transfer chamber (7) and a guide pipe (8). The transfer chamber (7) is fixedly installed at the center of the upper surface of the rotary table (2). The bottom end of the casting pipe (6) extends into the upper opening of the transfer chamber (7). Multiple guide pipes (8) are fixedly connected to the bottom end of the transfer chamber (7), and each guide pipe (8) communicates with the inner cavity of the transfer chamber (7). The impregnation temperature control assembly includes a first heating element (9) and a second heating element (10). The first heating element (9) is fixedly installed on the inside of the heat insulation cover (11). Multiple independent second heating elements (10) are arranged in layers in the vertical direction, with at least three layers, each layer having independent temperature control, and are fixedly installed on the inner wall of the outer chamber (5). A molding die (12) is provided with a vent pipe (29) that communicates with the inner cavity of the molding die (12) on its surface. Multiple molding dies (12) are detachably fixed on the surface of the rotating table (2), and the multiple molding dies (12) are arranged in a ring array in the outer cavity (5). The end of the guide pipe (8) away from the transfer chamber (7) is connected to the inner cavity of the molding die (12). The molding die (12) includes a die base (13) and a die shell (14). The die shell (14) is fixedly installed on the upper side of the die base (13). The die base (13) has a lower storage cavity (15) inside. The die shell (14) has a molding cavity (30) and an upper storage cavity (16) inside. The die base (13) is inserted into the end of the guide pipe (8). The guide pipe (8) is connected to the molding cavity (30) through the lower storage cavity (15). The molding cavity (30) is connected to the vent pipe (29) through the upper storage cavity (16). A sealing block (18) is slidably installed in the lower storage cavity (15), and a transmission seat (19) is slidably inserted on the surface of the mold base (13). The end of the transmission seat (19) is fixedly connected to the sealing block (18). A pneumatic impact hammer (20) is fixedly installed inside the heat preservation furnace (1), and the telescopic end of the pneumatic impact hammer (20) faces the transmission seat (19).

2. The directional solidification casting equipment for complex low-internal-stress aluminum alloy structures according to claim 1, characterized in that: The mold shell (14) is provided with a compensation channel (17) inside. The upper and lower ends of the compensation channel (17) are connected to the upper storage cavity (16) and the lower storage cavity (15) respectively. The compensation channel (17) is connected to the molding cavity (30) through multiple branch channels.

3. The directional solidification casting equipment for complex low-stress aluminum alloy structures according to claim 1, characterized in that: An angle sensor (21) is installed at the bottom of the heat preservation furnace (1). The angle sensor (21) detects the rotation angle of the rotary table (2). When the telescopic end of the pneumatic impact hammer (20) is aligned with any transmission seat (19), the pneumatic impact hammer (20) impacts the transmission seat (19), causing the sealing block (18) to switch from the state at the lower end of the sealing compensation channel (17) to the state at the lower end of the sealing forming cavity (30).

4. The directional solidification casting equipment for complex low-stress aluminum alloy structures according to claim 1, characterized in that: An annular gas hood (22) is fixedly installed at the bottom end of the casting pipe (6). The annular gas hood (22) covers the gap between the casting pipe (6) and the transfer chamber (7). An inert gas supply pipe connected to the annular gas hood (22) is fixedly installed on the upper side of the heat preservation furnace (1).

5. The directional solidification casting equipment for complex low-stress aluminum alloy structures according to claim 1, characterized in that: The heat preservation furnace (1) includes a furnace base (23) and a furnace body (24). The furnace body (24) is fixedly installed on the upper side of the furnace base (23), and a circulating cooling pipe is embedded inside the furnace body (24).

6. The directional solidification casting equipment for complex low-stress aluminum alloy structures according to claim 5, characterized in that: The furnace body (24) is fixedly installed with an input air duct (25) and an output air duct (26). The output air duct (26) is connected to the outer chamber (5), and the input air duct (25) is connected to the lower space of the rotating table (2). The surface of the rotating table (2) is provided with several through holes (27).

7. The directional solidification casting equipment for complex low-internal-stress aluminum alloy structures according to claim 6, characterized in that: An operation window is provided on the surface of the furnace body (24), and a sealing door (28) is hinged to the opening of the operation window.

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