Aerospace thin-walled heat-resistant aluminum alloy case casting system and method

Abstract

The present application relates to a kind of aviation thin-walled heat-resistant aluminum alloy machine case casting system and method, system includes mould group, water tank, rotating platform and motor, water tank can provide cooling water for mould group, motor can drive rotating platform horizontal rotation, mould group includes mould and mould base, mould is fixedly connected to the upper end of mould base, the upper part of rotating platform is open, and mould base is fixed on the bottom upper end of inside of rotating platform.The method is: heating to mould, pouring, rotating platform rotates, water is sprayed towards mould, after casting solidifies, stop spraying and rotating, disassemble mould can take out casting.The present application can realize the forming and feeding of complex thin-walled heat-resistant aluminum alloy casting, improve the internal organization density of casting, eliminate shrinkage hole and shrinkage porosity defects.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of aviation material casting, and relates to a method for casting an aviation thin-walled heat-resistant aluminum alloy machine case. BACKGROUND

[0002] The outer containment case is one of important components of an aero-engine. The wall thickness of the casting is generally below 3 mm, and the overall structure is in the form of a truncated cone. Except for the installation edge which can be machined, the structures at other casting positions are not allowed to be machined, and the surface precision is required to be not less than Ra6.3. The overall size of the casting is not less than 300 mm*300 mm*500 mm, and the inner surface is not allowed to be machined. The casting has high requirements on heat resistance and strength, and can only select a high-strength heat-resistant aluminum alloy for casting. The heat-resistant aluminum alloy is an aluminum-copper-based alloy, but the high-strength heat-resistant aluminum alloy has problems such as wide crystallization temperature range, paste-like solidification, poor casting fluidity and large difficulty in feeding. Due to the large thin-walled area of the casting, the wax mold used in the investment casting has insufficient strength and will be deformed. In the sand mold gravity casting process, the alloy liquid has poor fluidity, and the thin-walled position has a pouring deficiency defect. In the counter-gravity casting process, it is difficult to transmit the feeding pressure to the inside of the casting after the skin of the casting is solidified, resulting in shrinkage defects in the inside. SUMMARY

[0003] OBJECTIVE

[0004] To solve the problems in the prior art of casting the thin-walled heat-resistant aluminum alloy machine case, the present application provides a method for casting an aviation thin-walled heat-resistant aluminum alloy machine case.

[0005] TECHNICAL SCHEME

[0006] The aviation thin-walled heat-resistant aluminum alloy machine case casting system comprises a mold set, a water tank, a rotating platform and a motor. The water tank can provide cooling water for the mold set, and the motor can drive the rotating platform to rotate horizontally. The mold set comprises a mold and a mold base. The mold is fixedly connected to the upper end of the mold base. The upper part of the rotating platform is open, and the mold base is fixed to the bottom upper end of the inner side of the rotating platform.

[0007] Further, the mold comprises a central mold and a peripheral mold connected together. The central mold is provided with a sprue cup. The lower part of the sprue cup is provided with an alloy liquid storage area cover. The inside of the alloy liquid storage area cover is an alloy liquid storage area. The mold base is provided with a plurality of runners. The alloy liquid storage area is communicated with the runners. The peripheral mold is provided with a casting cavity. The casting cavity is also communicated with the runners. The upper end of the casting cavity is provided with a riser. The riser is provided with a vent hole. The mold is provided with a heating device.

[0008] Further, the heating device comprises a mold heating rod, a heating rod support plate and a heating rod power supply. The mold heating rod is fixed between the central mold and the peripheral mold through the heating rod support plate. The heating rod support plate is connected to the heating rod power supply.

[0009] Further, the outer periphery of the central mold is uniformly fixed with a plurality of support vertical plates, the support vertical plates are in contact with the outer periphery mold, and the central mold is separated from the bottom of the outer periphery mold by a graphite ring.

[0010] Further, the outer periphery of the rotating platform is provided with a rolling bearing, the rolling bearing is located in the upper equipment base, and one side of the rotating platform is provided with a rotating speed sensor.

[0011] Further, the rotating shaft of the motor is fixed with a driving pulley, the lower part of the rotating platform is fixed with a driven pulley, the driving pulley and the driven pulley are connected through a transmission belt, the lower part of the rotating platform is provided with a rotating bearing and a tapered roller bearing, and the rotating bearing and the tapered roller bearing are located on the inner side of the lower equipment base.

[0012] Further, the heating rod power supply, the rotating speed sensor and the motor are electrically connected with an industrial computer.

[0013] Further, the water tank is connected with an upper water pump through a pipeline, the upper water pump can extract water in the water tank, a valve is arranged on the pipeline connected with the water outlet of the upper water pump, the pipeline connected with the water outlet of the upper water pump is also provided with a cooling water spout, the cooling water spout is located between the rotating platform and the mold and faces the mold, a water outlet is arranged on the lower side of the rotating platform, a water collecting tank is arranged on the lower side of the water outlet, the bottom surface of the water collecting tank is in a slope shape, the bottom end of the slope is provided with a water outlet, a residue collecting tank is arranged on the lower side of the water outlet of the slope, the water tank is also connected with a water pumping pump through a pipeline, the water pumping pump can extract water in the residue collecting tank into the water tank, and a partition plate for separating water and waste residue is arranged in the residue collecting tank.

[0014] Further, the alloy liquid storage area cover is in an inverted cone shape, the taper is 1:0.8-1:1.2, and the gate is a fan shape with the inside being wide and the outside being narrow, and the fan angle is 22°-28°.

[0015] A method for casting an aviation thin-walled heat-resistant aluminum alloy machine case using the system, the mold is assembled and heated before pouring, the heating is to a temperature of 9-11 ℃ above the liquidus temperature, the alloy liquid in the ladle is poured into the pouring cup, the pouring is completed within 10 s, immediately after the pouring is completed, the motor is controlled to start and drive the rotating platform to rotate, the rotating speed of the rotating platform is 40-60 r / min, 2 minutes after the pouring is completed, the rotating speed of the rotating platform is increased, and the rotating speed of the rotating platform is increased to 180-220 r / min, at this time, under the action of the centrifugal force, the alloy liquid flows from the alloy liquid storage area to the direction of the casting cavity along the gate, then the upper water pump and the water pumping pump are started to circulate the cooling water, the cooling water is sprayed towards the mold through the cooling water spout, after the casting is solidified, the spraying and the rotating are stopped, and the mold can be disassembled to take out the casting.

[0016] Advantages and effects

[0017] The present application realizes the forming and feeding of complex thin-walled heat-resistant aluminum alloy castings by developing an aviation thin-walled heat-resistant aluminum alloy machine case casting system and method, generates a temperature gradient in the way of internal heating and external cooling, and breaks the grains through rotation to avoid the feeding channel blockage caused by paste-like solidification, so that the alloy liquid in the core of the mold flows outward under the action of centrifugal force to produce feeding pressure on part of the alloy liquid of the casting, improve the internal organization density of the casting, and eliminate shrinkage and porosity defects. BRIEF DESCRIPTION OF DRAWINGS

[0018] The present application will be further described below in combination with the drawings and specific embodiments. The protection scope of the present application is not limited to the following content.

[0019] Figure 1 It is a schematic diagram of the overall structure of an aviation thin-walled heat-resistant aluminum alloy machine case casting system.

[0020] Figure 2 It is a schematic diagram of the structure of the mold and the mold base.

[0021] Figure 3 It is a schematic diagram of the structure of the mold base from the top.

[0022] Figure 4 It is a schematic diagram of the structure at the graphite ring.

[0023] Figure 5 It is a flowchart schematic diagram of a method for casting an aviation thin-walled heat-resistant aluminum alloy machine case.

[0024] BRIEF DESCRIPTION OF DRAWINGS: 1. Water tank, 2. Water pump, 3. Water pump, 4. Valve, 5. Drainage port, 6. Water collecting tank, 7. Slag collecting tank, 8. Cooling water nozzle, 9. Support stand, 10. Alloy liquid storage area cover, 11. Sprue cup, 12. Ladle, 13. Mold heating rod, 14. Heating rod support plate, 15. Mold, 16. Graphite ring, 17. Mold base, 18. Heating rod power supply, 19. Rotating platform, 20. Rolling bearing, 21. Upper equipment base, 22. Rotational speed sensor, 23. Industrial computer, 24. Transmission belt, 25. Driving pulley, 26. Motor, 27. Rotating bearing, 28. Driven pulley, 29. Tapered roller bearing, 30. Lower equipment base, 31. Runner, 32. Feeding head, 33. Alloy liquid storage area, 34. Casting cavity, 35. Positioning groove. DETAILED DESCRIPTION

[0025] As Figure 1 , Figure 2 , Figure 3 and Figure 4As shown, an aviation thin-walled heat-resistant aluminum alloy case casting system is characterized by comprising a mold set, a water tank 1, a rotating platform 19 and a motor 26, the water tank 1 can provide cooling water for the mold set, the motor 26 can drive the rotating platform 19 to rotate horizontally, the mold set comprises a mold 15 and a mold base 17, the mold 15 is fixedly connected to the upper end of the mold base 17, the upper part of the rotating platform 19 is open, and the mold base 17 is fixed to the bottom upper end of the inner side of the rotating platform 19.

[0026] The mold 15 comprises a central mold and a peripheral mold connected together, the central mold is provided with a sprue cup 11, the sprue cup 11 is internally provided with a ceramic filter sheet, the lower end of the ceramic filter sheet is a right-angle channel, the lower part of the sprue cup 11 is provided with an alloy liquid storage area cover 10, the inside of the alloy liquid storage area cover 10 is an alloy liquid storage area 33, the mold base 17 is provided with a plurality of sprue runners 31, the alloy liquid storage area 33 is communicated with the sprue runners 31, the alloy liquid storage area cover 10 is a reverse taper type, the taper is 1:0.8-1:1.2, the sprue runner 31 is a fan shape with the inside wide and the outside narrow, the fan angle is 22°-28°, and the rotation generated pressure can be transmitted to the casting. The peripheral mold is internally provided with a casting cavity 34, the casting cavity 34 is also communicated with the sprue runners 31, the upper end of the casting cavity 34 is provided with a riser 32, the riser 32 is provided with an exhaust hole, a plurality of support vertical plates 9 are uniformly and fixedly arranged on the periphery of the central mold, the support vertical plates 9 are in contact with the peripheral mold, the bottom of the central mold and the peripheral mold are clamped apart by a graphite ring 16, due to the different expansions of the molds inside and outside the graphite ring 16, the graphite ring 16 can play a buffering role, reduce the stress on the casting, and thus can effectively reduce the cracking defects of the casting. The mold 15 is provided with a heating device, the heating device comprises a mold heating rod 13, a heating rod support plate 14 and a heating rod power supply 18, the mold heating rod 13 is fixed between the central mold and the peripheral mold through the heating rod support plate 14, and the heating rod support plate 14 is connected to the heating rod power supply 18.

[0027] The rotating platform 19 is provided with a rolling bearing 20 on the periphery, the rolling bearing 20 is located in an upper equipment base 21, the upper equipment base 21 is used for being fixed on other fixing devices during use, and one side of the rotating platform 19 is provided with a rotating speed sensor 22. The rotating shaft of the motor 26 is fixedly provided with a driving pulley 25, the lower part of the rotating platform 19 is fixedly provided with a driven pulley 28, the driving pulley 25 and the driven pulley 28 are connected through a transmission belt 24, the lower part of the rotating platform 19 is provided with a rotating bearing 27 and a tapered roller bearing 29 on the periphery, and the rotating bearing 27 and the tapered roller bearing 29 are located on the inner side of a lower equipment base 30. The heating rod power supply 18, the rotating speed sensor 22 and the motor 26 are electrically connected with an industrial computer 23.

[0028] The water tank 1 is connected with an upper water pump 3 capable of extracting water in the water tank 1 outward through a pipeline, the pipeline connected with the water outlet of the upper water pump 3 is provided with a valve 4, and the pipeline connected with the water outlet of the upper water pump 3 is further provided with a cooling water spout 8, the cooling water spout 8 is located between the rotating platform 19 and the mold 15 and faces the mold 15, the rotating platform 19 is provided with a water outlet 5 at the lower side of the cooling water spout 8, the water outlet 5 is provided with a water collecting tank 6 at the lower side, the bottom surface of the water collecting tank 6 is in a slope shape, the bottom end of the slope is provided with a water outlet, the lower side of the water outlet of the slope is provided with a residue collecting tank 7, the water tank 1 is further connected with a water pump 2 capable of extracting water in the residue collecting tank 7 into the water tank 1 through a pipeline, and the residue collecting tank 7 is provided with a partition plate for separating water and waste residue.

[0029] As shown in the accompanying drawings, Figure 5 A method for casting an aviation thin-walled heat-resistant aluminum alloy case using the above system is shown in the accompanying drawings, the mold is assembled and heated before pouring, and the temperature is heated to 9-11 ℃ above the liquidus temperature, so as to generate sufficient centrifugal force to make the alloy liquid in the alloy liquid storage area 33 supplement the shrinkage in the direction of the casting, the alloy liquid in the pouring ladle 12 is poured into the sprue cup 11, and the pouring is completed within 10 s, immediately after the pouring is completed, the motor 26 is controlled to start and drive the rotating platform 19 to rotate, the rotating speed of the rotating platform 19 is 40-60 r / min, 2 minutes after the pouring is completed, the rotating speed of the rotating platform 19 is increased, and the rotating speed of the rotating platform 19 is increased to 180-220 r / min, at this time, under the action of the centrifugal force, the alloy liquid flows from the alloy liquid storage area 33 to the direction of the casting cavity 34 along the runner 31, and a supplement shrinkage pressure is generated, at the same time, with the rotation, the already solidified grains are twisted and broken, and more grains are formed, which can effectively refine the grains, achieve the purpose of refining the grains and improving the mechanical properties of the casting, then the upper water pump 3 and the water pump 2 are started to circulate the cooling water, and the cooling water is sprayed towards the mold through the cooling water spout 8, after the casting is solidified, the water spraying and rotating are stopped, and the mold can be disassembled to take out the casting.

[0030] The case structure core design of the gating system is to ensure the complete filling and cooling control of the outer-duct case, the metal mold is selected as the mold, and a set of gating system is designed for this type of casting, which is different from the existing aluminum alloy sand mold gravity and counter-gravity casting gating system. The principle is to form a solidification temperature gradient conducive to the shrinkage of this type of casting through cooling and heating of the casting, and at the same time, through the action of external force (centrifugal force), the grains are broken to refine the grains and microstructure, the shrinkage channel is unblocked, and the alloy liquid supplement shrinkage pressure is increased, thereby obtaining a complete shape, dense microstructure, and thin-walled heat-resistant aluminum alloy case casting.

[0031] Obviously, the above embodiments of the present application are merely example for clearly explaining the present application, and are not intended to limit the embodiments of the present application. For those skilled in the art, on the basis of the above description, other different forms of changes or variations can also be made, and here all the embodiments cannot be exhausted, and any obvious changes or variations derived from the technical solutions of the present application still fall within the protection scope of the present application.

Claims

1. A casting system for thin-walled heat-resistant aluminum alloy casings for aircraft, characterized in that: The system includes a mold assembly, a water tank (1), a rotating platform (19), and a motor (26). The water tank (1) can provide cooling water to the mold assembly, and the motor (26) can drive the rotating platform (19) to rotate horizontally. The mold assembly includes a mold (15) and a mold base (17). The mold (15) is fixedly connected to the upper end of the mold base (17). The upper part of the rotating platform (19) is open, and the mold base (17) is fixed to the upper bottom of the inner side of the rotating platform (19). The mold (15) includes a central mold and an outer peripheral mold connected together. The central mold is provided with a pouring cup (11). The lower part of the pouring cup (11) is provided with an alloy liquid storage area cover (10). The interior of the alloy liquid storage area cover (10) is an alloy liquid storage area (33). The mold base (17) is provided with multiple runners (31). The alloy liquid storage area (33) and the runners (31) are connected. The outer peripheral mold is provided with a casting cavity (34). The casting cavity (34) and the runners (31) are also connected. The upper end of the casting cavity (34) is provided with a riser (32). The riser (32) is provided with a vent hole. The mold (15) is provided with a heating device. The heating device includes a mold heating rod (13), a heating rod support plate (14), and a heating rod power supply (18). The mold heating rod (13) is fixed between the central mold and the outer peripheral mold through the heating rod support plate (14), and the heating rod support plate (14) is connected to the heating rod power supply (18). Multiple support plates (9) are evenly distributed and fixed on the outer periphery of the central mold. The support plates (9) are in contact with the outer peripheral mold. Graphite rings (16) separate the bottom of the central mold from the bottom of the outer peripheral mold.

2. The aerospace thin-walled heat-resistant aluminum alloy casing casting system according to claim 1, characterized in that: A rolling bearing (20) is provided on the outer periphery of the rotating platform (19). The rolling bearing (20) is located inside the upper equipment base (21). A speed sensor (22) is provided on one side of the rotating platform (19).

3. The aerospace thin-walled heat-resistant aluminum alloy casing casting system according to claim 2, characterized in that: A drive pulley (25) is fixed on the rotating shaft of the motor (26), and a driven pulley (28) is fixed on the lower part of the rotating platform (19). The drive pulley (25) and the driven pulley (28) are connected by a transmission belt (24). A rotating bearing (27) and a tapered roller bearing (29) are provided on the lower outer periphery of the rotating platform (19). The rotating bearing (27) and the tapered roller bearing (29) are located inside the lower equipment base (30).

4. The aerospace thin-walled heat-resistant aluminum alloy casing casting system according to claim 3, characterized in that: The heating rod power supply (18), speed sensor (22) and motor (26) are electrically connected to an industrial control computer (23).

5. The aerospace thin-walled heat-resistant aluminum alloy casing casting system according to claim 1, characterized in that: The water tank (1) is connected to a water pump (3) that can draw water out of the water tank (1) via a pipe. The water outlet of the water pump (3) is connected to a pipe with a valve (4). The water outlet of the water pump (3) is also connected to a cooling water nozzle (8). The cooling water nozzle (8) is located between the rotating platform (19) and the mold (15) and faces the mold (15). The rotating platform (19) is provided with a drain outlet (5) below the cooling water nozzle (8). A water collection tank (6) is provided below the drain outlet (5). The bottom surface of the water collection tank (6) is sloping. A water outlet is provided at the bottom of the slope. A slag collection tank (7) is provided below the water outlet of the slope. The water tank (1) is also connected to a water pump (2) that can draw water from the slag collection tank (7) into the water tank (1) via a pipe. A partition for separating water and waste residue is provided in the slag collection tank (7).

6. The aerospace thin-walled heat-resistant aluminum alloy casing casting system according to claim 1, characterized in that: The outer cover (10) of the alloy liquid storage area is an inverted cone shape with a taper of 1:0.8 to 1:1.

2. The gating channel (31) is a fan shape with a wider inner side and a narrower outer side, with a fan angle of 22° to 28°.

7. A method for casting aerospace thin-walled heat-resistant aluminum alloy casings using the system as described in claim 1, characterized in that: Before pouring, the mold is assembled and heated to 9-11°C above the liquidus temperature. The alloy liquid in the ladle (12) is poured into the pouring cup (11). The pouring is completed within 10 seconds. Immediately after the pouring is completed, the motor (26) is started, which drives the rotating platform (19) to rotate. The rotation speed of the rotating platform (19) is 40-60 r / min. Two minutes after the pouring is completed, the rotation speed of the rotating platform (19) is increased to 180-220 r / min. At this time, under the action of centrifugal force, the alloy liquid flows from the alloy liquid storage area (33) along the runner (31) to the casting cavity (34). Next, the water pump (3) and the water pump (2) are started to circulate the cooling water. Water is sprayed towards the mold through the cooling water nozzle (8). After the casting solidifies, the water spraying and rotation are stopped. The casting can be removed by disassembling the mold.

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