Casting method of multi-layer separation cavity aircraft engine main engine box

Abstract

The invention discloses a casting method for a multi-layer separated-cavity aircraft engine main engine box. The casting method sequentially comprises the following steps that modeling is conducted on the multi-layer separated-cavity aircraft engine main engine box; designing a pouring system; four parting surfaces are determined, and all types are designed; a pouring gate mold, a lower mold, a middle mold, an upper mold, a cover mold, detachable sand molds, mold cores and oil way sand cores are subjected to 3D printing; the mold cores, the oil way sand cores and the detachable sand molds are loaded into the corresponding sand molds correspondingly; sequentially hoisting and stacking the pouring gate mold, the lower mold, the middle mold, the upper mold and the cover mold from bottom to top to form an integral sand mold; the whole sand mold is hoisted into a sand box, sand filling molding is conducted, after resin sand is solidified, the sand box is hoisted above a sealing cover of a heat preservation furnace, a liquid rising pipe is installed in the center of the sealing cover, and an upper end opening of the liquid rising pipe is in butt joint with a pressure adjusting pouring gate in the center of the bottom of the pouring gate mold; magnesium alloy liquid is smelted, and under the action of air pressure, the magnesium alloy liquid is subjected to upward mold filling through a liquid rising pipe and a pressure adjusting sprue; the casting quality of the engine main case can be improved.

Description

Technical Field

[0001] The invention relates to magnesium alloy casting, in particular to a casting method for a multi-layer compartment aircraft engine main casing, belonging to the technical field of complex casting casting technology. Background Art

[0002] As an indispensable part of aviation equipment, aircraft engines are the decisive factors in aircraft performance, reliability and cost. Their technological development plays an extremely important role in national defense and the national economy. As the main load-bearing part of the engine, the casing has a complex structure, high design difficulty, complex production process and relatively long production cycle. Therefore, the design and production efficiency of the engine casing occupy the vast majority of the research and development of this engine. However, with the rapid development of my country's aviation industry, the demand for lighter, more integrated and more versatile casings is increasing, and the structural design is becoming more and more complex. It has become a trend to replace aluminum alloy with magnesium alloy. At present, the mainstream engine main casing is still mainly made of aluminum alloy, and the design structure is relatively simple. Casting complex thin-walled casings with magnesium alloy is still a major problem, not only because magnesium is easy to burn and has a high safety risk, but also because the pass rate is low, the cost is high and the cycle is long.

[0003] The structure of the engine main casing casting is complex, with as many as five layers of compartments. The casting of the complex cavity is difficult, and the casting is extremely difficult. Traditional blades are mostly solid blades, and many blades of the new casing casting are hollow blades. The traditional mold sand mold is difficult to make, easy to break and deform, and the casting processability is extremely poor. Similar castings are mostly made with molds, with high production costs and long production cycles. Compared with other sand castings, the engine main casing casting has very high requirements for dimensional accuracy and surface roughness.

[0004] In addition, many non-machined surfaces of the engine main case casting cannot be connected to the runner or placed with risers for shrinkage compensation. If chillers are placed on the non-machined surfaces, the surface roughness of the casting will not meet the requirements of the design drawings.

[0005] What is even more difficult is that the main engine casing has a complex lubrication oil circuit designed inside the casing casting, which can reduce the external piping of the machine, simplify the structure of the engine, and improve the reliability and stability of the engine. At the same time, it can also improve the overall sealing and pressure resistance of the engine, so that the machine can work normally under high pressure, high temperature and high speed environment. However, the diameter of the multiple built-in slender oil circuits is very thin but very long, and there are only two mouth fulcrums. Because the oil circuit is thin, long and tortuous, the strength is not enough, and it is easy to deform or even be broken during pouring. Simply opening the mold to make the core, due to the special-shaped structure, the mold production is complex, the cycle is long, and it is difficult to split. In addition, its strength cannot be guaranteed during production, and it is prone to defects such as deformation, breakage, and difficulty in sand removal in the later stage.

[0006] For aircraft engine main casing castings, special heat treatment tooling needs to be customized to prevent deformation of the product during the heat treatment process. Reasonable heat treatment equipment can improve dimensional accuracy, avoid dimensional deviation, and reduce later manual correction. As the model of the aircraft engine main casing changes, the corresponding special heat treatment tooling needs to be remade, which has a long production cycle and is economically wasteful. Summary of the invention

[0007] The purpose of this section is to summarize some aspects of embodiments of the present invention and briefly introduce some preferred embodiments. Some simplifications or omissions may be made in this section and the abstract of the specification of this application and the title of the invention, and such simplifications or omissions cannot be used to limit the scope of the present invention.

[0008] In view of the above problems and / or the problems existing in the prior art, the present invention is proposed.

[0009] The purpose of the present invention is to overcome the problems existing in the prior art and provide a casting method for a main casing of a multi-layer compartment aircraft engine, which can simultaneously meet the casting requirements of thick and large parts and thin-walled parts of the multi-layer compartment magnesium alloy casting, avoid air holding and shrinkage of non-machined surfaces, realize sequential solidification of the casting, reliably compensate for shrinkage and avoid insufficient pouring, and improve the quality of the casting.

[0010] In order to solve the above technical problems, a casting method of a multi-layer compartment aircraft engine main casing of the present invention comprises the following steps in sequence: S1. Modeling of the main engine case of a multi-layered aircraft engine; S2. Design the pouring system; S3. Determine four parting surfaces, and design the runner type, lower mold, middle mold, upper mold, cover mold, each removable sand mold, each core and oil circuit sand core; S4, 3D printing runner type, lower type, middle type, upper type, cover type, each removable sand mold, each core and oil circuit sand core; S5, respectively placing each core, oil passage sand core and disassembled sand mold into the corresponding sand mold; S6. Hoist the stacked runner mold, lower mold, middle mold, upper mold and cover mold from bottom to top to form an integral sand mold; S7, hoisting the whole sand mold into the sand box, filling sand for molding, and after the resin sand is solidified, hoisting the sand box above the sealing cover of the insulation furnace, a liquid riser is installed in the center of the sealing cover, and the upper end of the liquid riser is connected to the pressure regulating gate at the center of the bottom of the runner mold; S8. The magnesium alloy liquid is melted, and under the action of gas pressure, the magnesium alloy liquid is filled upward into the mold through the riser and the pressure regulating gate.

[0011] Furthermore, in step S1, the multi-layer compartment aircraft engine main casing includes a circular casing shell, a lower flange is provided at the lower port of the casing shell, a lubricating oil tank is provided on the lower outer circumference of the casing shell, and a plurality of bosses are provided on the outer wall of the lubricating oil tank; an upwardly extending center tube is provided at the upper center of the casing shell, the upper part of the center tube exceeds the casing shell and is provided with an upper flange, and the annular space between the lower outer wall of the center tube and the upper inner wall of the casing shell is connected as a whole by a plurality of hollow blades.

[0012] Furthermore, one end of the inner cavity space of each hollow blade is connected to the lower cavity of the central tube, and the other end is connected to the annular compartment in the upper thin wall of the casing shell.

[0013] Furthermore, in the pouring system described in step S2, the upper end of the pressure regulating gate is connected to the bottom of the center of the circular pancake-shaped horizontal runner, and a plurality of straight runners extending upward are evenly arranged in concentric circles at the center of the upper end surface of the circular pancake-shaped horizontal runner, and the outer wall of each straight runner is connected to the inner wall of the upper flange through the straight runner inner gate; A plurality of inner circumferential down gates are evenly arranged on the middle circumference of the upper end surface of the circular pancake-shaped horizontal runner and connected to the bottom circumference of the casing shell; a plurality of outer circumferential down gates are evenly arranged on the outer circumference of the upper end surface of the circular pancake-shaped horizontal runner and connected to the bottom circumference of the lubricating oil tank; The outer peripheral wall of the circular pancake-shaped horizontal runner is connected to at least two upwardly extending runners, and the top of each runner is connected to the outer periphery of the annular horizontal runner through a radial inner runner. The outer periphery of the annular horizontal runner is connected to multiple radial outer runners, and the inner side of the bottom of each radial outer runner is connected to the outer end face of the lower flange through an inner upper gate.

[0014] Furthermore, the inner side wall of each of the tubes is connected to the corresponding boss through a tube inner gate; the outer side of the bottom of each of the radial outer runners is connected to the corresponding boss through an outer upper gate.

[0015] Furthermore, the casting hot spots are provided with chillers, and the surfaces of the chillers facing the non-machined surfaces of the castings are covered with a sand layer 5-8 mm thick.

[0016] Furthermore, a center tube inner step with an enlarged diameter is provided at the bottom of the center tube, and a plurality of exhaust holes are evenly provided along the outer circumference of the center tube inner step, each exhaust hole extending upward and higher than the top of the annular runner.

[0017] Furthermore, in step S4, the cavity in the runner mold matches the shape of the lower runner, and the four corners of the upper end surface of the runner mold are respectively provided with runner-type tenons protruding upward; the four corners of the upper end surface of the lower mold are respectively provided with notches that are engaged with the runner-type tenons, and the cavity of the lower mold matches the shape of the middle runner, the upper flange, the center tube and the top wall of the lubricating oil tank, and the cavity of the lower mold is provided with blade cores and lubricating oil heat dissipation oil circuit sand cores.

[0018] Furthermore, the inner side of each blade core is connected to the annular center tube compartment core, and the outer side of each blade core is connected to the annular compartment core in the upper thin wall of the casing shell; the bottom of the center tube compartment core and the annular compartment core are respectively provided with a plurality of supporting process hole sand cores, and each supporting process hole sand core is embedded in the positioning groove of the lower mold; the inner walls of the annular compartment core are connected by upper and lower layers of rod-shaped reinforcement ribs, and before the middle mold is combined with the lower mold, each rod-shaped reinforcement rib is cut off.

[0019] Furthermore, a plurality of oil circuit supporting sand cores are provided at the bottom of the outer wall of the lubricating oil heat dissipation oil circuit sand core, and each oil circuit supporting sand core is respectively embedded in the corresponding oil circuit positioning countersunk hole of the lower mold. The lubricating oil heat dissipation oil circuit sand core is assembled from multiple sections along the length direction, and the facing ends of the sections are respectively overlapped and connected with each other by half tenons, and a central air hole is provided along the axis of the lubricating oil heat dissipation oil circuit sand core.

[0020] Furthermore, in step S4, the four corners of the lower end face of the medium mold are respectively provided with medium-sized lower tenons, and each medium-sized lower tenon is respectively fitted with the notches at the four corners of the upper end face of the lower mold; the center of the medium-sized cavity is provided with a central inner cavity core and a lower flange inner cavity core, and the periphery of the medium-sized cavity is provided with a lubricating oil tank core that matches the shape of the inner cavity of the lubricating oil tank.

[0021] Furthermore, two sections of arc-shaped reinforcement ribs are provided along the inner circumference of the lubricating oil tank core, the outer walls of the two arc-shaped reinforcement ribs are connected to the inner circumferential wall of the lubricating oil tank core through a plurality of supporting short columns, the two ends of the arc-shaped reinforcement ribs are connected through straight rod reinforcement ribs, and the inner circumference of the arc-shaped reinforcement ribs is connected to the straight rod reinforcement ribs through a plurality of radial reinforcement ribs.

[0022] Furthermore, the three corners of the medium mold are respectively provided with through medium-sized positioning holes, and the three positioning legs of the positioning tooling are respectively inserted through the corresponding medium-sized positioning holes and embedded in the corresponding countersunk holes of the lower mold. The upper ends of the three positioning legs are connected to the corners of the detection platform, and a hollow center hole is provided in the center of the detection platform. A plurality of measuring bosses are provided on the lower end face of the detection platform, and the lower end face of each measuring boss is fitted with the corresponding measuring point of the lubricating oil tank core.

[0023] Furthermore, after the lubricating oil tank core is positioned properly, the positioning tool is pulled out; the upper mold is stacked on the middle mold, and the four corners of the upper end face of the middle mold are respectively provided with medium-sized upper tenons, and each medium-sized upper tenon is respectively fitted with the notch at the four corners of the lower end face of the upper mold; the cavity of the upper mold matches the shape of the upper runner.

[0024] Furthermore, the method further comprises the following steps: S9, after cooling and solidification, sand is removed to obtain a multi-layer compartment aircraft engine main engine case blank; S10. Heat treatment is performed on the main engine casing by using a heat treatment tool; the heat treatment tool comprises an annular chassis, a plurality of support rod positioning holes are evenly distributed on a first circumference of the annular chassis close to the periphery, a plurality of pad positioning grooves are evenly distributed on a second circumference inside the first circumference, a recessed annular groove is provided on the inner side of the second circumference, a plurality of inner support positioning grooves are evenly distributed on the upper edge of the inner circumference of the annular chassis, a plurality of hollow water inlet grooves are evenly provided in the empty spaces of the circumference where the support rod positioning holes and the pad positioning grooves are located and on the bottom wall of the annular groove; a support positioning assembly is installed in the inner support positioning groove, a T-shaped pad with a width on the top and a narrowness on the bottom is embedded in the pad positioning groove, and a rotating support rod is inserted in the support rod positioning hole; The lower flange of the main casing of the aircraft engine is supported in the annular groove, the top of the support and positioning assembly is supported below the step in the center tube; the top surface of the T-shaped pad is supported at the bottom of the lubricating oil tank; the upper end of the rotating support rod is supported below the outer boss of the main casing of the aircraft engine.

[0025] Furthermore, a diameter-adjusting metal ring is embedded in the outer peripheral wall of the annular groove, and the inner periphery of the diameter-adjusting metal ring abuts against the outer periphery of the lower flange of the main casing of the aircraft engine; The support and positioning assembly includes a support seat, a support seat boss is provided on the bottom of the support seat facing the annular chassis, the support seat boss is embedded in the corresponding inner support and positioning groove and fixed by screws, the support seat is provided with a vertical guide groove, the vertical guide groove is provided with a support column extending upward, the top of the support column abuts under the step in the center tube of the main casing of the aircraft engine, and a locking screw is screwed on the side wall of the support seat, and the inner end of the locking screw abuts against the support column.

[0026] Compared with the prior art, the present invention has achieved the following beneficial effects: 1. By setting up a counter-gravity pressure-regulated pouring method, the molten metal flows under pressure, and the filling capacity is relatively improved. A stable and adjustable flow rate and pressure can be provided, ensuring that each cavity is fully poured to obtain a dense structure, and the entire casting is crystallized under pressure without pinholes and shrinkage defects.

[0027] 2. The bottom adopts a round pancake-shaped horizontal runner with an overall large plane. On the one hand, it is conducive to the stability of alloy liquid filling, and on the other hand, the increased cross-sectional area can ensure that all ingates are filled with liquid at the same time; the design of the upper and lower double horizontal runners can simultaneously feed the casting from the upper and lower sides, increase the overall pressure, improve the shrinkage effect, and reduce the heat nodes caused by traditional risers; the tube design on the outside plays the role of connecting the upper and lower horizontal runners, and on the other hand, according to the characteristics of the product structure, point gates are opened on it to feed the thick parts of the side wall. The design of multiple ingates stabilizes the flow rate, directly connects the horizontal runner, has sufficient pressure, and improves the shrinkage effect; it can directly feed the thick parts and each compartment, and can also reduce the size of the ingates, avoid the generation of large heat nodes, and improve product quality.

[0028] 3. Use 3D sand molds instead of molds and powder molding to reduce costs, improve efficiency, and obtain sand molds with high processability, high operability, and high precision, especially complex surfaces or slender curves, to improve the surface roughness level and dimensional accuracy of castings, ensure the quality and size of castings, reduce production costs, shorten production cycles, improve production efficiency, reduce scrap rates and rework workload, and improve product qualification rates and production cycles.

[0029] 4. The slender oil circuit is supported and split into multiple short sections for assembly. After the oil circuit is assembled, all gaps are filled with paint to reduce the generation of excess materials such as seams and nodules in the oil circuit of the casting. This can well solve the problems of structural deformation or fracture of the oil circuit during the assembly and baking process, which is conducive to controlling the wall thickness of the aircraft engine, meeting the needs of aircraft designers without changing the design, reducing costs and increasing efficiency, and reducing economic losses. A central air hole is set along the axis of the slender oil circuit to facilitate the exhaust of the sand core, reduce the risk of air suffocation and insufficient pouring of the oil circuit of the magnesium-aluminum alloy casting, and improve the qualified rate of the product; it is also convenient for workers to clean the sand, greatly reducing the labor intensity of workers, greatly improving work efficiency, and protecting the physical and mental health of workers.

[0030] 5. The chiller is cooled by sand isolation, which can improve the surface roughness and dimensional accuracy of the casting. The casting dimensional tolerance is ±0.37mm, and the surface roughness is ≤3.2um. It can avoid shrinkage defects caused by the inability to place runners and chillers on some non-processed surfaces.

[0031] 6. The design of the vent hole plays a role in exhausting air and reducing the occurrence of pore defects. On the other hand, it plays a role in collecting slag and solving the problems of air holding and shrinkage of non-machined surfaces of magnesium alloy castings.

[0032] 7. The heat treatment tooling of the present invention can solve the problem of heat treatment deformation of aircraft engine castings, avoid dimensional deviation, improve dimensional accuracy, and make the finished aircraft engine main casing meet the requirements of the design drawings; it can be used for multiple models of aircraft engine main casings, improve the versatility of the tooling, reduce production costs, and shorten the production cycle; avoid mechanical correction due to heat treatment deformation, and reduce the labor intensity of workers. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative labor. The drawings are only provided for reference and explanation, not for limiting the present invention. Among them: Figure 1 The invention is a three-dimensional image of the aircraft engine main casing casting in an upright position. Figure 1 ; Figure 2 The invention is a three-dimensional image of the aircraft engine main casing casting in an upright position. Figure 2 ; Figure 3 It is an inverted front view of the aircraft engine main casing casting in the present invention; Figure 4 It is a three-dimensional view of an inverted aircraft engine main casing casting in the present invention; Figure 5 A three-dimensional diagram of a pouring system for a multi-layer compartment aircraft engine main casing according to the present invention; Figure 6 A top view of a pouring system for a multi-layer compartment aircraft engine main casing according to the present invention; Figure 7 It is a three-dimensional diagram after the assembly of the present invention is completed; Figure 8 It is a three-dimensional diagram of the split type in the present invention; Fig. 9 It is a complete exploded view of each type in the present invention; Fig.10 It is a top view of the blade core in the lower mold; Fig.11 This is a three-dimensional picture of the blade core in the lower mold before it is hoisted; Fig.12 This is the installation status diagram of the lubricating oil heat dissipation oil circuit sand core on the medium; Fig.13 This is a three-dimensional picture of the lubricating oil tank core before hoisting; Fig.14 This is the inspection status diagram of the lubricating oil tank core after it is hoisted into place; Fig.15It is a three-dimensional picture of the annular chassis in the heat treatment tooling; Fig.16 It is a three-dimensional picture of the heat treatment tooling; Fig.17 It is a three-dimensional enlarged view of the support and positioning components in the heat treatment tooling; Fig.18 It is a three-dimensional enlarged view of the rotating support rod in the heat treatment tooling; Fig.19 This is a three-dimensional enlarged view of the T-shaped pad in the heat treatment tooling; Fig. 20 It is a working state diagram of the heat treatment tooling in the present invention; In the figure: 1. Main case of aircraft engine; 1a. Upper flange; 1b. Step inside center tube; 1c. Hollow blade; 1d. Lower flange; 1e. Lubricating oil tank; 1f. Mounting seat; 1g. Lug; 1h. Oil inlet of oil tank; 1j. Oil outlet of oil tank; 2. Pressure regulating gate; 3. Round pancake runner; 4. Sprue; 5. Sprue ingate; 6. Inner circumference down gate; 7. Outer circumference down gate; 8. Through barrel; 9. Through barrel ingate; 10. Radial inner runner; 11. Annular runner; 12. Radial outer runner; 13. Inner upper gate; 14. Outer upper gate; 15. Vent hole; 16. Chill; 17. Sprue type; 17a. Sprue type tenon; 17b. Handle; 18. Lower mold; 18a. Oil channel positioning countersink; 18b. Leg positioning countersink; 18c. Lower mold dismantling sand mold; 19. Medium; 19a. Medium lower tenon; 19b. Medium upper tenon; 19c. Medium positioning hole; 19d. Medium dismantling block; 19e. Emergency oil line installation block; 20. Upper mold; 21. Cover mold; 22. Center tube cavity core; 23. Blade core; 24. Annular cavity core; 25. Support process hole sand core; 26. Rod-shaped reinforcement rib; 27. Front return oil circuit sand core; 28. Rear return oil circuit sand core; 29. ​​Emergency oil circuit sand core; 30. Lubricating oil heat dissipation circuit sand core; 30a. Oil circuit support sand core; 31. Center cavity core; 32. Lubricating oil tank core; 33. Straight rod reinforcement rib; 34. Radial reinforcement rib; 35. Arc reinforcement rib; 36. Support short column; 37. Inspection platform; 38. Measuring boss; 39. Positioning leg; 40. Lower flange cavity core; 41. Annular chassis; 41a. Inner support positioning groove; 41b. Support rod positioning hole; 41c. Annular groove; 41d. Pad positioning groove; 41e. Hollow water inlet groove; 42. Support positioning assembly; 42a. Support seat; 42b. Support seat boss; 42c. Support column; 42d. Set screw; 43. Rotating support rod: 43a. Supporting and positioning sleeve; 43b. Rotating screw rod; 43c. Circular support block; 44. Diameter-adjusting metal ring; 45. T-shaped spacer. DETAILED DESCRIPTION

[0034] In the following description of the present invention, the directions or positional relationships indicated by terms such as "up", "down", "front", "back", "left", "right", "inside" and "outside" are based on the directions or positional relationships shown in the accompanying drawings and are only for the convenience of describing the present invention and simplifying the description, and do not mean that the device must have a specific direction.

[0035] In order to make the technical means, creative features, objectives and effects of the present invention easier to understand, the present invention is further described below in conjunction with specific diagrams. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them.

[0036] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art of the present invention. The terms used in the specification of the present invention herein are only for the purpose of describing specific embodiments and are not intended to limit the present invention.

[0037] like Figures 1 to 3 As shown, the multi-layer compartment aircraft engine main casing of the present invention includes a circular casing shell, a lower flange 1d is provided at the lower end of the casing shell, a lubricating oil cavity is integrated on the lower periphery of the casing shell to form a lubricating oil tank 1e wrapped around the lower periphery of the casing shell; a mounting seat 1f, a support ear 1g, an oil inlet 1h and an oil outlet 1j are provided on the outer wall of the lubricating oil tank 1e, thereby forming a plurality of external bosses on the outer wall of the lubricating oil tank 1e.

[0038] The upper center of the casing shell is provided with a center tube extending upward, the upper part of the center tube exceeds the casing shell and is provided with an upper flange 1a, and the lower end of the center hole of the center tube is provided with a center tube inner step 1b with an expanded diameter. The annular space between the lower outer wall of the center tube and the upper inner wall of the casing shell is connected as a whole through a plurality of hollow blades 1c. One end of the inner cavity space of each hollow blade 1c is connected to the lower cavity of the center tube, and the other end is connected to the annular compartment in the upper thin wall of the casing shell.

[0039] like Figures 4 to 6 As shown, during pouring, the engine main casing is inverted, that is, the upper flange 1a is located at the lower end, and the lower flange 1d is located at the upper end. A circular pancake-shaped horizontal runner 3 is provided below the upper flange 1a, a pressure regulating gate 2 is provided at the bottom center of the circular pancake-shaped horizontal runner 3, and seven straight runners 4 extending upward are evenly provided in concentric circles at the center of the upper end surface of the circular pancake-shaped horizontal runner 3, and the outer wall of each straight runner 4 is connected to the inner wall of the upper flange 1a through the straight runner inner gate 5.

[0040] A plurality of inner down gates 6 are evenly arranged on the middle circumference of the upper end surface of the circular pancake-shaped cross runner 3 and connected to the bottom circumference of the casing shell; a plurality of outer down gates 7 are evenly arranged on the outer circumference of the upper end surface of the circular pancake-shaped cross runner 3 and connected to the bottom circumference of the lubricating oil tank 1e.

[0041] The outer peripheral wall of the circular pancake-shaped cross runner 3 is connected to at least two upwardly extending tubes 8, and the inner wall of each tube 8 is connected to the corresponding boss through the tube inner gate 9; the top of each tube 8 is connected to the outer periphery of the annular cross runner 11 through a radial inner runner 10, and the outer periphery of the annular cross runner 11 is connected to a plurality of radial outer runners 12, and the inner side of the bottom of each radial outer runner 12 is connected to the outer end face of the lower flange 1d through an inner upper gate 13, and the outer side of the bottom of each radial outer runner 12 is connected to the corresponding boss through an outer upper gate 14.

[0042] The molten magnesium alloy liquid is injected upward from the pressure regulating gate 2 into the circular pancake-shaped runner 3. The magnesium alloy liquid in the central area of ​​the circular pancake-shaped runner 3 flows upward along each sprue 4 and fills the upper flange 1a through the gate 5 in each sprue.

[0043] The larger plane of the circular pancake-shaped horizontal runner 3 causes each sprue 4, each inner peripheral down gate 6, outer peripheral down gate 7, and tube 8 to rise liquid synchronously. The inner peripheral down gate 6 fills the bottom circumference of the casing shell, and the outer peripheral down gate 7 fills the bottom circumference of the lubricating oil tank 1e. At the same time, the magnesium alloy liquid rises to the top through the two tubes, enters the annular horizontal runner 11 along the radial inner runner 10, and then enters each radial outer runner 12 from the annular horizontal runner 11. Each radial outer runner 12 compensates the circumference of the lower flange 1d through the inner upper gate 13, and the tube inner gate 9 and the outer upper gate 14 compensate the boss.

[0044] The pouring is carried out by means of pressure regulation in the counter-gravity pouring method, which enhances the fluidity of the solution, improves the filling capacity, ensures that each layer of the cavity is fully poured, allows the casting to crystallize and solidify under pressure, obtains a denser structure, and prevents the generation of dense pores and shrinkage defects.

[0045] A plurality of chills 16 are evenly spaced on the circumference of the lower flange 1d and spaced from the inner upper pouring gate 13; chills 16 are also placed on the hot spots such as the bosses on the outer periphery of the casting. For the machined surface of the casting, the chills 16 can be close to the casting, strengthen the chilling effect, and improve the internal quality of the casting.

[0046] Because magnesium alloy is easy to burn and has a large amount of gas, and traditional sand casting also produces a large amount of gas, it is easy to cause air holding. The bottom of the center tube is provided with an enlarged center tube inner step 1b, and a plurality of exhaust holes 15 are evenly arranged on the outer circumference of the center tube inner step 1b. Each exhaust hole 15 extends upward and is higher than the top of the annular horizontal runner to guide the gas to be discharged, which can reduce the occurrence of air holding and greatly improve the qualified rate of products.

[0047] The thin-walled parts of the mainframe casting are basically non-machined surfaces. The overall structure is only 3mm thick, the dimensional tolerance is only allowed to be within ±0.5mm, and the roughness of the non-machined surface is required to be less than 3.2μm. The design requirements are very high and the difficulty is great.

[0048] In the conventional method, the chiller is close to the casting, and the surface will be rough. Since the surface roughness and dimensional tolerance requirements of the main casing casting product are high, the surface of the casting cannot be close to the chiller and the gate.

[0049] However, if the gate and chiller are not placed, shrinkage will occur. Therefore, the following technical solution is adopted: by placing a steel or iron chiller with strong chilling in the sand layer, separated from the non-machined surface of the casting by 5-8mm sand layer, it can not only play the role of chilling and absorbing heat to prevent shrinkage, but also ensure the size and surface roughness of the product to prevent shrinkage.

[0050] By adopting the evacuation method, exhaust pipes were designed in advance on the 3D sand mold, and cold iron grooves were designed between the casting cavity and the sand mold. Through experimental comparison, shrinkage was reduced by 1 / 2, completely solving the problems of air holding and shrinkage on non-machined surfaces of magnesium alloy castings.

[0051] The casting method of the multi-layer compartment aircraft engine main casing of the present invention comprises the following steps in sequence: S1. Modeling of multi-layer compartment aircraft engine main box, such as Figures 1 to 4 As shown; S2. Design the pouring system, such as Figure 5 , Figure 6 As shown; S3, such as Figures 7 to 14 As shown, four parting surfaces are determined, and a runner mold 17, a lower mold 18, a middle mold 19, an upper mold 20, a cover mold 21, various removable sand molds, various cores and oil passage sand cores are designed; S4, 3D printed runner mold 17, lower mold 18, middle mold 19, upper mold 20, cover mold 21, various disassembled sand molds, various cores and oil circuit sand cores; by using 3D printing to make sand molds and sand cores, instead of traditional mold opening and powder molding methods, 3D sand mold printing sand mold time only takes 3-4 days, but mold making time takes 30-40 days, the two are 10 times different in time and economy. This complex casing is more advantageous to use 3D printed sand molds, which not only greatly improves production efficiency, but also reduces labor intensity. Economically, it reduces 90% of costs, improves efficiency, saves 60%-80% of total manufacturing time, and shortens the production cycle; S5, each core, oil circuit sand core and disassembled sand mold are respectively loaded into the corresponding sand mold; wherein the disassembled sand mold 18c of the lower mold is mainly for the convenience of installing the chiller and painting the local features, and is assembled into the lower mold 18 from top to bottom; S6, hoisting the stacked runner mold 17, the lower mold 18, the middle mold 19, the upper mold 20 and the cover mold 21 from bottom to top in sequence to form an integral sand mold; S7, hoisting the whole sand mold into the sand box, filling sand molding, after the resin sand is solidified, hoisting the sand box above the sealing cover of the insulation furnace, the center of the sealing cover is equipped with a liquid riser, the upper end of the liquid riser is connected to the pressure regulating gate at the bottom center of the runner mold 17; S8, melting the magnesium alloy liquid, and under the action of gas pressure, the magnesium alloy liquid is filled upward through the liquid riser and the pressure regulating gate; S9, after cooling and solidification, sand is removed to obtain a multi-layer compartment aircraft engine main engine case blank; S10. Use heat treatment tooling to perform heat treatment on the engine main casing.

[0052] In step S4, the cavity in the runner mold 17 matches the shape of the lower runners such as the pressure regulating gate, the round pancake-shaped horizontal runner, the lower part of the tube and each straight runner, and the four corners of the upper end surface of the runner mold 17 are respectively provided with runner-shaped convex tenons 17a protruding upward; the outer wall of the runner mold 17 is symmetrically provided with handles 17b, and the outer walls of the other lower molds 18, the middle mold 19, and the upper mold 20 are also respectively provided with corresponding handles. The four corners of the upper end surface of the lower mold 18 are respectively provided with notches to fit with the runner-shaped convex tenons 17a, and the cavity of the lower mold 18 matches the shape of the upper part of each straight runner, the inner gate of the straight runner, the middle section of the tube and other middle runners, the upper flange, the center tube and the top wall of the lubricating oil tank, and the cavity of the lower mold 18 is provided with each blade core 23 and the lubricating oil heat dissipation oil path sand core 30.

[0053] like Fig.10 , Fig.11 As shown, the inner side of each blade core 23 is connected to the annular center tube compartment core 22, and the outer side of each blade core 23 is connected to the annular compartment core 24 in the thin wall of the upper part of the casing shell. The overall center of gravity is on the center tube compartment core 22. If the blade core 23 with a thickness of only 3-4mm is connected, the sand mold is very easy to break. The inner walls of the annular compartment core 24 are connected by upper and lower two layers of rod-shaped reinforcement ribs 26 to ensure the strength of the sand mold and effectively prevent the deformation of the sand mold in the preheating stage, and it can also be convenient for workers to operate and carry. At the same time, the bottoms of the center tube compartment core 22 and the annular compartment core 24 are respectively provided with a plurality of supporting process hole sand cores 25, and each supporting process hole sand core 25 is embedded in the positioning groove of the lower mold 18, which not only provides support, but also ensures accurate positioning. Before the middle mold 19 is combined with the lower mold 18, each rod-shaped reinforcement rib 26 is cut off.

[0054] like Fig.12As shown, the strength of the special-shaped oil circuit cannot be guaranteed by simply opening the mold to make the core, and it is easy to break and deform, and the solid air permeability is poor, and the traditional mold method cannot produce a hollow complex curved pipe. In the present invention, a plurality of oil circuit support sand cores 30a are provided at the bottom of the outer wall of the lubricating oil heat dissipation oil circuit sand core 30, and each oil circuit support sand core 30a is respectively embedded in the corresponding oil circuit positioning countersunk hole 18a of the lower mold 18 to ensure accurate core placement. Since the length of the oil circuit support sand core 30a is nearly 500mm, the lubricating oil heat dissipation oil circuit sand core 30 is assembled from multiple sections along the length direction, and the facing ends between the sections are respectively connected to each other by half tenons, and the gap between the half tenon mating surfaces ensures the accuracy of the oil circuit assembly size and the uniform wall thickness of the oil circuit; it can also prevent the oil circuit from deformation and breakage, improve the dimensional accuracy of the product, and on the other hand, it can facilitate workers to brush the protective coating and the sand removal of the inner cavity in the later stage, greatly improving work efficiency and reducing the labor intensity of workers. A central air hole is provided along the axis of the lubricating oil heat dissipation oil circuit sand core 30 to improve the exhaust effect during the pouring process.

[0055] The present invention solves the problem of fracture and deformation of complex oil circuits by adding support in sections at the middle part of the oil circuit sand core, opening process holes, and completing the oil circuit by welding in the later stage; the shape and wall thickness of the product oil circuit can be better guaranteed, the dimensional accuracy is higher, and the fracture and deformation of the slender oil circuit are reduced to 1 / 10 of the original; the design requirements of the aircraft main engine box are met, and the manual labor intensity of workers is reduced.

[0056] The four corners of the lower end face of the medium-sized mold 19 are respectively provided with medium-sized lower tenons 19a, and each medium-sized lower tenon 19a is respectively fitted with the notches at the four corners of the upper end face of the lower mold 18; the center of the cavity of the medium-sized mold 19 is provided with a central inner cavity core 31 and a lower flange inner cavity core 40, and the outer periphery of the cavity of the medium-sized mold 19 is provided with a lubricating oil tank core 32 matching the shape of the inner cavity of the lubricating oil tank.

[0057] like Fig.13 As shown, the lubricating oil tank core 32 is an integral annular sand mold with a larger inner diameter. The sand mold on one side is thicker and higher, and the sand mold on the other side is thinner and narrower. The center of gravity is uneven, and the risk of breakage during transportation is greater. Two arc-shaped reinforcement ribs 35 are arranged along the inner circumference of the lubricating oil tank core 32. The outer walls of the two arc-shaped reinforcement ribs 35 are connected to the inner circumferential wall of the lubricating oil tank core 32 through multiple supporting short columns 36, respectively. The two ends of the arc-shaped reinforcement ribs 35 are connected by straight rod reinforcement ribs 33. The inner circumference of the arc-shaped reinforcement ribs 35 is connected to the straight rod reinforcement ribs 33 through multiple radial reinforcement ribs 34. The strength of the sand mold is ensured and the risk of deformation is reduced by each reinforcement rib. The front return oil circuit sand core 27, the rear return oil circuit sand core 28, and the emergency oil circuit sand core 29 can be installed on the lubricating oil tank core 32 in advance, and then the medium-sized dismantling block 19d and the emergency oil circuit installation block 19e are installed. The dismantling block is mainly used to facilitate the painting, or to avoid interference during the assembly process, or to avoid the risk of collision, etc.

[0058] like Fig.14 As shown, the center of gravity of the medium mold 19 is biased to one side during the molding process, which makes it easy to droop, resulting in incomplete sand mold assembly. In order to ensure the accuracy of the sand mold assembly size, it is generally necessary to measure the size height of multiple points, but the curved surface object lacks a measurement reference and is difficult to measure.

[0059] Therefore, when printing the 3D sand mold, the positioning tooling for measurement is directly printed out. The three corners of the medium mold 19 are respectively provided with through medium-sized positioning holes 19c, and the three positioning legs 39 of the positioning tooling pass through the corresponding medium-sized positioning holes 19c and are embedded in the corresponding leg positioning countersunk holes 18b of the lower mold 18. The upper ends of the three positioning legs 39 are connected to the corners of the detection platform 37, and the center of the detection platform 37 is provided with a hollow center hole, and the lower end surface of the detection platform 37 is provided with a plurality of measuring bosses 38. When the three positioning legs 39 are inserted to the bottom, the lower end surface of each measuring boss 38 fits with the corresponding measuring point of the lubricating oil tank core 32, and it can be judged that the sand mold is assembled in place and the accumulated error meets the requirements, without measuring the size, which is convenient and fast with high dimensional accuracy and high efficiency.

[0060] After the lubricating oil tank core 32 is positioned properly, the positioning tool is pulled out; the upper mold 20 is stacked on the middle mold 19, and the four corners of the upper end surface of the middle mold 19 are respectively provided with medium-sized upper tenons 19b, and each medium-sized upper tenon 19b is respectively fitted with the notches at the four corners of the lower end surface of the upper mold 20; the cavity of the upper mold 20 matches the shape of the upper runners such as the upper part of the cylinder, the gate in the cylinder, the radial inner runner, the annular cross runner, the radial outer runner, the inner upper gate, and the outer upper gate.

[0061] like Figures 15 to 20 As shown, the heat treatment tooling includes an annular chassis 41, a support positioning assembly 42, a rotating support rod 43, a diameter-adjusting metal ring 44 and a T-shaped pad 45. A plurality of support rod positioning holes 41b are evenly distributed on the first circumference of the annular chassis 41 near the periphery, a plurality of pad positioning grooves 41d are evenly distributed on the second circumference inside the first circumference, a concave annular groove 41c is provided on the inner side of the second circumference, a plurality of inner support positioning grooves 41a are evenly distributed on the upper edge of the inner circumference of the annular chassis 41, and a plurality of hollow water inlet grooves 41e are evenly distributed in the gaps of the circumference where the support rod positioning holes 41b and the pad positioning grooves 41d are located and on the bottom wall of the annular groove 41c. Hollow water inlet grooves 41e are also evenly distributed on the circumference outside the first circumference, so as to facilitate rapid immersion in water during cooling.

[0062] The lower flange 1d of the aircraft engine main casing 1 is supported in the annular groove 41c. The sizes of the lower flange 1d of different models of main casings are different. Usually, the inner diameter of the outer peripheral wall of the annular groove 41c is larger. Therefore, a diameter-adjusting metal ring 44 is embedded in the outer peripheral wall of the annular groove 41c. The inner periphery of the diameter-adjusting metal ring 44 abuts against the outer periphery of the lower flange 1d of the aircraft engine main casing 1 to fix the lower flange 1d.

[0063] A T-shaped pad 45 which is wide at the top and narrow at the bottom is embedded in the pad positioning groove 41d. The T-shaped pad 45 is bent along the arc of the circle where it is located. The lower thin-walled part of the T-shaped pad 45 is inserted into the pad positioning groove 41d to play a positioning role. The top surface of the T-shaped pad 45 is supported on the bottom of the lubricating oil tank 1e of the main casing 1 of the aircraft engine.

[0064] A support positioning assembly 42 is installed in the inner support positioning groove 41a, and the support positioning assembly 42 includes a support seat 42a. The support seat 42a is provided with a support seat boss 42b at the bottom facing the annular chassis 41, and the support seat boss 42b is embedded in the corresponding inner support positioning groove 41a and fixed by screws. The support seat 42a is provided with a vertical guide groove, and the vertical guide groove is provided with a support column 42c extending upward, and the top of the support column 42c abuts against the lower step 1b in the center tube of the aircraft engine main casing 1. A locking screw 42d is screwed on the side wall of the support seat 42a, and the inner end of the locking screw 42d abuts against the support column 42c.

[0065] A rotating support rod 43 is inserted into the support rod positioning hole 41b, and a support positioning sleeve 43a is provided at the lower end of the rotating support rod 43. The reduced diameter lower end of the support positioning sleeve 43a is inserted into the corresponding support rod positioning hole 41b. A rotating screw rod 43b is threadedly connected to the upper end screw of the support positioning sleeve 43a, and the top of the rotating screw rod 43b is against the lower side of the outer boss of the aircraft engine main casing 1 through a circular support block 43c. The installation position of the rotating support rod 43 can be selected according to the position and height of the outer boss, and adjusted to a suitable jacking height to support and limit the casting, thereby preventing the thermal expansion and contraction effect during the heat treatment process.

[0066] The heat treatment tooling is installed in the following order: first measure the outer diameter of the lower flange of the engine main case and select a suitable diameter-adjusting metal ring 44; then install the T-shaped pad 45 on the annular chassis 41, and then put the lower flange 1d of the aircraft engine main case 1 into the annular groove 41c on the annular chassis 41, and then embed the diameter-adjusting metal ring 44 between the annular groove 41c and the outer periphery of the lower flange of the main case to fix the lower flange 1d; at this time, the T-shaped pad 45 is supported on the bottom of the main case oil tank, and a gasket can be inserted under the T-shaped pad 45 to adjust its top surface height.

[0067] Next, the rotating support rod 43 is installed into the support rod positioning hole 41b, and the top height of the rotating screw rod 43b is adjusted so that the circular support block 43c abuts against the bottom of the corresponding outer boss.

[0068] Finally, each support positioning assembly 42 is installed into the corresponding inner support positioning groove 41a, the top height of the support column 42c is adjusted so that it abuts against the bottom of the step 1b inside the center tube, and the set screw 42d is locked.

[0069] The above is only a preferred embodiment of the present invention, which shows and describes the basic principles, main features and advantages of the present invention, but does not limit the scope of patent protection of the present invention. Those skilled in the art should understand that the present invention is not limited by the above embodiments. In addition to the above embodiments, the present invention may have other implementation modes without departing from the spirit and scope of the present invention. The present invention may also have various changes and improvements, and all technical solutions formed by equivalent substitution or equivalent transformation fall within the scope of protection required by the present invention. The scope of protection required by the present invention is defined by the attached claims and their equivalents. The technical features not described in the present invention can be realized by or using existing technologies, which will not be repeated here.

Claims

1. A method for casting a multi-layer compartment aircraft engine main casing, characterized in that: The steps are as follows: S1. Modeling of the main engine case of a multi-layered aircraft engine; S2. Design the pouring system; S3. Determine four parting surfaces, and design the runner type, lower mold, middle mold, upper mold, cover mold, each removable sand mold, each core and oil circuit sand core; S4, 3D printing runner type, lower type, middle type, upper type, cover type, each removable sand mold, each core and oil circuit sand core; S5, respectively placing each core, oil passage sand core and disassembled sand mold into the corresponding sand mold; S6. Hoist the stacked runner mold, lower mold, middle mold, upper mold and cover mold from bottom to top to form an integral sand mold; S7, hoisting the whole sand mold into the sand box, filling sand for molding, and after the resin sand is solidified, hoisting the sand box above the sealing cover of the insulation furnace, a liquid riser is installed in the center of the sealing cover, and the upper end of the liquid riser is connected to the pressure regulating gate at the center of the bottom of the runner mold; S8. The magnesium alloy liquid is melted, and under the action of gas pressure, the magnesium alloy liquid is filled upward into the mold through the riser and the pressure regulating gate.

2. The casting method of the multi-layer compartment aircraft engine main casing according to claim 1, characterized in that: In step S1, the multi-layer compartment aircraft engine main casing includes a circular casing shell, a lower flange is provided at the lower port of the casing shell, a lubricating oil tank is provided on the lower outer circumference of the casing shell, and a plurality of bosses are provided on the outer wall of the lubricating oil tank; an upwardly extending center tube is provided at the upper center of the casing shell, the upper part of the center tube exceeds the casing shell and is provided with an upper flange, and the annular space between the lower outer wall of the center tube and the upper inner wall of the casing shell is connected as a whole by a plurality of hollow blades.

3. The casting method of the multi-layer compartment aircraft engine main casing according to claim 2, characterized in that: One end of the inner cavity space of each hollow blade is communicated with the lower cavity of the central tube, and the other end is communicated with the annular compartment in the upper thin wall of the casing shell.

4. The casting method of the multi-layer compartment aircraft engine main casing according to claim 1, characterized in that: In the pouring system of step S2, the upper end of the pressure regulating gate is connected to the bottom of the center of the circular pancake-shaped horizontal runner, and a plurality of sprues extending upward are evenly arranged in concentric circles at the center of the upper end surface of the circular pancake-shaped horizontal runner, and the outer wall of each sprue is connected to the inner wall of the upper flange through the sprue inner gate; A plurality of inner circumferential down gates are evenly arranged on the middle circumference of the upper end surface of the circular pancake-shaped horizontal runner and connected to the bottom circumference of the casing shell; a plurality of outer circumferential down gates are evenly arranged on the outer circumference of the upper end surface of the circular pancake-shaped horizontal runner and connected to the bottom circumference of the lubricating oil tank; The outer peripheral wall of the circular pancake-shaped horizontal runner is connected to at least two upwardly extending runners, and the top of each runner is connected to the outer periphery of the annular horizontal runner through a radial inner runner. The outer periphery of the annular horizontal runner is connected to multiple radial outer runners, and the inner side of the bottom of each radial outer runner is connected to the outer end face of the lower flange through an inner upper gate.

5. The casting method of the multi-layer compartment aircraft engine main casing according to claim 4, characterized in that: The inner side wall of each of the tubes is connected to the corresponding boss through a tube inner gate; the outer side of the bottom of each of the radial outer flow runners is connected to the corresponding boss through an outer upper gate.

6. The casting method of the multi-layer compartment aircraft engine main casing according to claim 4, characterized in that: Chills are provided at the pouring hot spots, and the surfaces of the chills facing the non-machined surfaces of the castings are covered with a 5-8 mm thick sand layer.

7. The casting method of the multi-layer compartment aircraft engine main casing according to claim 4, characterized in that: The bottom of the central tube is provided with an enlarged central tube inner step, and a plurality of exhaust holes are evenly arranged along the outer circumference of the central tube inner step, each exhaust hole extending upward and higher than the top of the annular runner.

8. The casting method of the multi-layer compartment aircraft engine main casing according to claim 4, characterized in that: In step S4, the cavity in the runner mold matches the shape of the lower runner, and the four corners of the upper end surface of the runner mold are respectively provided with runner-type tenons protruding upward; the four corners of the upper end surface of the lower mold are respectively provided with notches that fit with the runner-type tenons, and the cavity of the lower mold matches the shape of the middle runner, the upper flange, the center tube and the top wall of the lubricating oil tank, and the cavity of the lower mold is provided with blade cores and lubricating oil heat dissipation oil circuit sand cores.

9. The casting method of the multi-layer compartment aircraft engine main casing according to claim 4, characterized in that: The inner side of each blade core is connected to the annular center tube compartment core, and the outer side of each blade core is connected to the annular compartment core in the thin wall of the upper part of the casing shell; the bottoms of the center tube compartment core and the annular compartment core are respectively provided with a plurality of supporting process hole sand cores, and each supporting process hole sand core is embedded in the positioning groove of the lower mold; the inner walls of the annular compartment core are connected by upper and lower layers of rod-shaped reinforcement ribs, and before the middle mold is combined with the lower mold, each rod-shaped reinforcement rib is cut off.

10. The casting method of the multi-layer compartment aircraft engine main casing according to claim 4, characterized in that: A plurality of oil circuit support sand cores are provided at the bottom of the outer wall of the lubricating oil heat dissipation oil circuit sand core, and each oil circuit support sand core is respectively embedded in the corresponding oil circuit positioning countersunk hole of the lower mold. The lubricating oil heat dissipation oil circuit sand core is assembled from multiple sections along the length direction, and the facing ends of the sections are respectively overlapped and connected with each other by half tenons, and a central air hole is provided along the axis of the lubricating oil heat dissipation oil circuit sand core.

11. The casting method of the multi-layer compartment aircraft engine main casing according to claim 8, characterized in that: In step S4, the four corners of the lower end face of the medium mold are respectively provided with medium-sized lower tenons, and each medium-sized lower tenon is respectively fitted with the notches at the four corners of the upper end face of the lower mold; the center of the medium-sized cavity is provided with a central inner cavity core and a lower flange inner cavity core, and the outer periphery of the medium-sized cavity is provided with a lubricating oil tank core that matches the shape of the inner cavity of the lubricating oil tank.

12. The casting method of the multi-layer compartment aircraft engine main casing according to claim 11, characterized in that: Two sections of arc-shaped reinforcement ribs are arranged along the inner circumference of the lubricating oil tank core. The outer walls of the two arc-shaped reinforcement ribs are connected to the inner circumferential wall of the lubricating oil tank core through a plurality of supporting short columns, the two ends of the arc-shaped reinforcement ribs are connected through straight rod reinforcement ribs, and the inner circumference of the arc-shaped reinforcement ribs is connected to the straight rod reinforcement ribs through a plurality of radial reinforcement ribs.

13. The casting method of the multi-layer compartment aircraft engine main casing according to claim 12, characterized in that: The three corners of the medium mold are respectively provided with through medium-sized positioning holes, and the three positioning legs of the positioning tooling are respectively inserted into the corresponding countersunk holes of the lower mold through the corresponding medium-sized positioning holes, and the upper ends of the three positioning legs are connected to the corners of the detection platform. The center of the detection platform is provided with a hollow center hole, and the lower end face of the detection platform is provided with a plurality of measuring bosses, and the lower end face of each measuring boss is in contact with the corresponding measuring point of the lubricating oil tank core.

14. The casting method of the multi-layer compartment aircraft engine main casing according to claim 13, characterized in that: After the lubricating oil tank core is positioned qualified, the positioning tool is pulled out; the upper mold is stacked on the middle mold, and the four corners of the upper end face of the middle mold are respectively provided with medium-sized upper tenons, and each medium-sized upper tenon is respectively fitted with the notch at the four corners of the lower end face of the upper mold; the cavity of the upper mold matches the shape of the upper runner.

15. The casting method of the multi-layer compartment aircraft engine main casing according to claim 14, characterized in that: The following steps are also included: S9, after cooling and solidification, sand is removed to obtain a multi-layer compartment aircraft engine main engine case blank; S10. Heat treatment is performed on the main engine casing by using a heat treatment tool; the heat treatment tool comprises an annular chassis, a plurality of support rod positioning holes are evenly distributed on a first circumference of the annular chassis close to the periphery, a plurality of pad positioning grooves are evenly distributed on a second circumference inside the first circumference, a recessed annular groove is provided on the inner side of the second circumference, a plurality of inner support positioning grooves are evenly distributed on the upper edge of the inner circumference of the annular chassis, a plurality of hollow water inlet grooves are evenly provided in the empty spaces of the circumference where the support rod positioning holes and the pad positioning grooves are located and on the bottom wall of the annular groove; a support positioning assembly is installed in the inner support positioning groove, a T-shaped pad with a width on the top and a narrowness on the bottom is embedded in the pad positioning groove, and a rotating support rod is inserted in the support rod positioning hole; The lower flange of the main casing of the aircraft engine is supported in the annular groove, the top of the support and positioning assembly is supported below the step in the center tube; the top surface of the T-shaped pad is supported at the bottom of the lubricating oil tank; the upper end of the rotating support rod is supported below the outer boss of the main casing of the aircraft engine.

16. The casting method of the multi-layer compartment aircraft engine main casing according to claim 15, characterized in that: A diameter-adjusting metal ring is embedded in the outer peripheral wall of the annular groove, and the inner periphery of the diameter-adjusting metal ring abuts against the outer periphery of the lower flange of the main engine case of the aircraft engine; The support and positioning assembly includes a support seat, a support seat boss is provided on the bottom of the support seat facing the annular chassis, the support seat boss is embedded in the corresponding inner support and positioning groove and fixed by screws, the support seat is provided with a vertical guide groove, the vertical guide groove is provided with a support column extending upward, the top of the support column abuts under the step in the center tube of the main casing of the aircraft engine, and a locking screw is screwed on the side wall of the support seat, and the inner end of the locking screw abuts against the support column.

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