Pouring method and application of a casing casting for an aero-engine

Abstract

The present invention provides a pouring method and application of a casing casting of an aeroengine, relating to the technical field of pouring. Specifically, the method includes the following steps: installing at least one pouring component in the middle of the support plate of the aeroengine casing, and introducing molten metal into the pouring component for bottom gating; the pouring component includes a straight section of the ingate, a liquid storage pool and a runner. The present invention provides a molten metal flow field different from the conventional pouring process through a new type of bilateral bottom gating process, supplemented by a pouring component with a specific structure, solves the defects of deformation and fracture of the ceramic core in the conventional pouring process, prevents the occurrence of phenomena such as eccentric core, core leakage and core breakage, greatly improves the filling and pouring qualification rate of the casting, and has good application prospects.

Description

Technical Field

[0001] The present invention relates to the technical field of casting, and in particular, to a casting method and application of an aero-engine casing casting. Background Art

[0002] Aero-engine casings are developing towards being larger and thinner-walled, and the cavity structure of the support plates is complex and narrow; taking the blades of a certain type of casing as an example, the thickest part of the cavity is 3.4 mm, and the thinnest part is only 0.67 mm, and the blade length can reach more than 130 mm; traditional coatings cannot be formed, and only the ceramic core forming process can be used. However, the ceramic core only solves the forming problem. For such a long and thin ceramic core, its low-temperature strength and high-temperature strength are inevitably low.

[0003] Currently, when the theoretical wall thickness requirement of the casing blade is 1.6 mm and investment casting is used for forming, the pouring temperature needs to be increased by more than 1500 °C; such a high pouring temperature poses extremely high requirements on the high-temperature resistance of the ceramic core; once the strength of the ceramic core is insufficient or the deflection is high, the ceramic core will break or deform under the impact of the molten steel (or other molten metal for casting) during the pouring process, and then eccentric core and core leakage defects will occur, ultimately resulting in the scrapping of the casting. In current production, the scrap rate caused by eccentric core and core leakage accounts for more than 90%, so it is necessary to optimize the pouring process.

[0004] For the above-mentioned type of aero-engine casing, the existing conventional pouring schemes can generally be summarized into the following two types: First, the molten steel flows in from both ends at the lower part of the support plate and converges in the middle of the support plate, that is, the conventional bottom gating; Second, the molten steel is injected from the top of the support plate, that is, the top gating. However, both of these two pouring processes have relatively large defects: the former has a certain impact force at the confluence of the support plates, giving a strong force to the fragile ceramic core and easily causing deformation or fracture of the ceramic core; the latter's molten steel flow field is difficult to control, and when the molten steel flow is disordered, it is easy to cause irregular deformation defects of the ceramic core.

[0005] In addition, currently, in order to form the whole casting, the ceramic core can also be positioned by means of metal wire positioning to prevent its deformation or fracture; however, this method is prone to cause casting defects, forming high-density slag inclusions or fluorescence defects, etc., and such processes still cannot meet the high-quality requirements of aero-engine casings.

[0006] In view of this, the present invention is specifically proposed. Summary of the Invention

[0007] The first object of the present invention is to provide a casting method for an aero-engine casing casting, and the casting method solves the technical defect that the existing pouring process is prone to cause deformation or fracture of the ceramic core and then scrapping of the casting, effectively reducing the phenomena of eccentric core, core leakage, and core breakage, and improving the filling qualification rate of the casting.

[0008] To achieve the above object of the present invention, the following technical solutions are specifically adopted:

[0009] A casting method for the blades of an aero-engine casing mainly includes the following steps: installing at least one casting assembly in the middle of the support plate of the aero-engine casing, and introducing molten metal into the casting assembly for bottom gating; the casting assembly includes a straight sprue section, a liquid storage pool and a runner.

[0010] Preferably, the straight sprue section, the liquid storage pool and the runner are sequentially connected and communicated.

[0011] Preferably, a liquid passage port is pre-set in the middle of the bottom of the support plate.

[0012] Preferably, the ratio of the length of the straight sprue section to the length of the support plate is 0.25 - 0.55; more preferably, the ratio of the length of the straight sprue section to the length of the support plate is 1 / 3 - 1 / 2.

[0013] Preferably, the ratio of the width of the straight sprue section to the wall thickness of the support plate is 1.5 - 2.5; more preferably, the ratio of the width of the straight sprue section to the wall thickness of the support plate is 2.

[0014] Preferably, the height of the straight sprue section is 3 mm - 15 mm; more preferably, the height of the straight sprue section is 5 mm - 10 mm.

[0015] Preferably, the ratio of the volume of the liquid storage pool to the volume of the straight sprue section is 2.5 - 5.5; more preferably, the ratio of the volume of the liquid storage pool to the volume of the straight sprue section is 3 - 5.

[0016] Preferably, the ratio of the cross-sectional area of the runner to the cross-sectional area of the liquid storage pool is 1 / 9 - 1 / 5.

[0017] Preferably, the temperature of the bottom gating is 1400°C - 1700°C; more preferably, the temperature of the bottom gating is 1500°C - 1600°C.

[0018] Preferably, before the bottom gating, the temperature of the preheated mold is raised to 800°C - 1200°C.

[0019] The second object of the present invention is to provide an aero-engine casing obtained by the casting method for the aero-engine casing casting as described above.

[0020] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0021] (1) The present invention provides a brand-new metal liquid flow field through a bilateral bottom-gating casting process, supplemented by a gating component with a specific structure, solving the defects of deformation and fracture of ceramic cores in conventional casting processes, preventing phenomena such as core offset, core leakage, and core breakage, and thus greatly improving the filling qualification rate of castings.

[0022] (2) By defining the specifications of the straight section of the ingate, the liquid storage pool, and the cross-riser of the gating component of the present invention, including cross-sectional area, volume, dimensions, etc., the control of the metal liquid flow rate and acting force is achieved, avoiding the impact of the metal liquid on the ceramic core and the casting defects generated thereby. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the drawings required for use in the description of the specific embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0024] Figure 1 The structural schematic diagram of the gating component of the present invention is provided;

[0025] Figure 2 The structural schematic diagram of the gating component adopted in the embodiment of the present invention is provided;

[0026] Figure 3 Another structural schematic diagram of the gating component adopted in the embodiment of the present invention is provided;

[0027] Figure 4 The usage schematic diagram of the gating component of the present invention is provided;

[0028] Figure 5 The metal liquid flow schematic diagrams of three casting processes are provided; Figure 5 (A), Figure 5 (B) respectively provide the flow schematic diagrams of a current process, Figure 5 (C) is the flow schematic diagram of the casting process of the present invention;

[0029] Figure 6 The assembly drawing of the casting and the gating component in the first direction in the embodiment is provided;

[0030] Figure 7 The assembly drawing of the casting and the gating component in the second direction in the embodiment is given;

[0031] Figure 8 The molten steel flow schematic diagram in the embodiment is given. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0032] The technical solution of the present invention will be clearly and completely described below in conjunction with the accompanying drawings and specific embodiments. However, those skilled in the art will understand that the following described embodiments are part of the embodiments of the present invention, rather than all of the embodiments, and are only used to illustrate the present invention and should not be construed as limiting the scope of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the scope of protection of the present invention. For those conditions not specified in the embodiments, they shall be carried out according to conventional conditions or conditions recommended by the manufacturer. For reagents or instruments whose manufacturers are not indicated, they are all conventional products that can be obtained through commercial purchase.

[0033] In the description of the present invention, it should be noted that the orientation or positional relationship indicated by the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. is based on the orientation or positional relationship shown in the accompanying drawings, and is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as limiting the present invention.

[0034] In the description of the present invention, it should be noted that unless otherwise clearly specified and defined, the terms "installation", "connection", and "connection" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific situations.

[0035] The present invention is used to solve the problem of forming high-temperature alloy casing castings of thin-walled or narrow-cavity types; by designing a new gating system to reduce the force on the ceramic core, the casting can be completely formed with a scrap rate far lower than the current process. The present invention can be implemented as follows:

[0036] A gating method for the blades of an aero-engine casing mainly includes the following steps: installing at least one gating component in the middle of the support plate of the aero-engine casing, and pouring molten metal into the gating component for bottom gating;

[0037] As a preferred embodiment, the structure of the gating component can be Figure 1 as shown; the gating component includes a straight sprue section, a reservoir, and a cross gate that are connected in sequence; the molten metal is poured into the cross gate, buffered in the reservoir, and enters the casting through the straight sprue section at a stable rate.

[0038] As a more preferred embodiment, the straight section of the ingate is perpendicular to the runner in space;

[0039] As a preferred embodiment, the number and installation positions of the pouring assemblies are selected according to the overall structure of the casting. Figure 4 A schematic diagram of the connection relationship between the pouring assembly of the present invention and the middle part of the support plate is provided; the number of the pouring assemblies is at least one, and the specific number of the pouring assemblies is not limited in the present invention;

[0040] As a more preferred embodiment, the pouring assembly further includes: an external runner connected to the runner; the external runner is used to extend the total length or position of the runner, so that the user can more conveniently perform the operation of pouring molten metal; when the number of the pouring assemblies is greater than one, the external runners can also be used to connect the runners in each of the pouring assemblies in series to form a unified molten metal inlet; the specific number of the external runners is not limited in the present invention;

[0041] As a preferred embodiment, the type of the molten metal is selected according to the pouring requirements, and the specific type of the molten metal is not limited in the present invention; typically but not restrictively, the molten metal may include molten steel, molten aluminum, aluminum-magnesium alloy liquid, molten iron, zinc-iron alloy liquid, etc.;

[0042] As a preferred embodiment, a liquid passage is preset in the middle of the bottom of the support plate for the introduction of the molten metal;

[0043] Figure 5 Schematic diagrams of the flow of molten metal of two current pouring processes and the pouring process of the present invention are provided; among them, Figure 5 (A) is the conventional bottom pouring type. When the molten metal introduced from both sides of the support plate converges in the middle of the support plate, an impact force is formed, causing the ceramic core to receive a strong flow force; Figure 5 (B) is the top pouring type, which cannot effectively control the flow of molten metal, and the high-density and high-quality molten metal is likely to break the fragile ceramic core due to the action of gravity; Figure 5 (C) is the special bottom pouring type of the present invention, which maximally avoids the influence on the ceramic core after the molten metal is injected.

[0044] As a preferred embodiment, the ratio of the length of the straight section of the ingate to the length of the support plate is 0.25 to 0.55, including but not limited to: 0.25, 0.30, 0.35, 0.40, 0.45, 0.50, 0.55; as a more preferred embodiment, the ratio of the length of the straight section of the ingate to the length of the support plate is 1 / 3 to 1 / 2.

[0045] As a preferred embodiment, the ratio of the width of the straight section of the inner gate to the wall thickness of the support plate is 1.5 to 2.5, including but not limited to: 1.5, 1.6, 1.7, 1.8, 1.9, 2.0, 2.1, 2.2, 2.3, 2.4, 2.5; As a more preferred embodiment, the ratio of the width of the straight section of the inner gate to the wall thickness of the support plate is 2.

[0046] As a preferred embodiment, the height of the straight section of the inner gate is 3 mm to 15 mm; As a more preferred embodiment, the height of the straight section of the inner gate is 5 mm to 10 mm, including but not limited to: 5 mm, 6 mm, 7 mm, 8 mm, 9 mm, 10 mm.

[0047] As a preferred embodiment, the ratio of the volume of the liquid storage pool to the volume of the straight section of the inner gate is 2.5 to 5.5; As a more preferred embodiment, the ratio of the volume of the liquid storage pool to the volume of the straight section of the inner gate is 3 to 5, including but not limited to: 3, 3.5, 4, 4.5, 5; In the present invention, the liquid storage pool functions to buffer the molten metal. When the molten metal enters the liquid storage pool, the impact force weakens, and it fills the liquid storage pool in a short time and then rises at a basically constant and slow rate.

[0048] As a preferred embodiment, the ratio of the cross-sectional area of the horizontal runner to the cross-sectional area of the liquid storage pool is 1 / 9 to 1 / 5; In the present invention, the horizontal runner serves as a channel for the molten metal source. According to the calculation and experiment based on the pouring rate of the molten metal and the value of the cross-sectional area of the horizontal runner during actual operation, when the horizontal runner can reduce the flow rate and provide sufficient head, the ratio of the cross-sectional area of the horizontal runner to the cross-sectional area of the liquid storage pool should be within the above limited range.

[0049] As a preferred embodiment, the temperature of the bottom gating is 1400 °C to 1700 °C; As a more preferred embodiment, the temperature of the bottom gating is 1500 °C to 1600 °C, including but not limited to: 1500 °C, 1510 °C, 1520 °C, 1530 °C, 1540 °C, 1550 °C, 1560 °C, 1570 °C, 1580 °C, 1590 °C, 1600 °C.

[0050] As a preferred embodiment, before performing the bottom gating, preheat the temperature of the mold to 800 °C to 1200 °C; As a more preferred embodiment, preheat the temperature of the mold to 900 °C to 1100 °C, including but not limited to: 900 °C, 920 °C, 940 °C, 960 °C, 980 °C, 1000 °C, 1020 °C, 1040 °C, 1060 °C, 1080 °C, 1100 °C.

[0051] Example

[0052] Use a large thin-walled and hollow casing assembly of a certain aero-engine as the casting part to be cast; it should be noted that the large thin-walled and hollow casing assembly of a certain aero-engine is partial and incomplete, and its assembly itself involves other confidentiality factors. Therefore, only a part is intercepted for the description of the casting process in the present invention; the other undisclosed structures of the assembly are irrelevant to the casting process of the present invention and will not affect the explanation of the casting process. Those skilled in the art can fully understand how to implement the casting process of the present invention based on the content disclosed in this embodiment.

[0053] Combine the components and wax molds of the large thin-walled and hollow casing assembly of a certain aero-engine. After preparing the membrane shell, a series of membrane shell cavities are formed. Install the casting assembly as shown in Figure 2 、 Figure 3 on the casting part to be cast; Figure 6 The combined drawing of the casting part to be cast - casting assembly after installation is given. Figure 7 is the combined drawing of the casting part to be cast - casting assembly after installation observed from another direction. In addition to the casting assembly as shown in Figure 2 、 Figure 3 Three externally connected pouring runners connected in sequence are also installed for connection to other structures or communication with the molten steel source.

[0054] Preheat the wax mold of the combined large thin-walled and hollow casing assembly of a certain aero-engine to a temperature of 1000°C; pour molten steel into the externally connected pouring runner, and the pouring temperature is 1550°C; Figure 8 The flow diagram of the molten steel is given. After the pouring is completed, cool for about 24 hours and wait for the molten steel to reach room temperature, cut and remove the membrane shell and the casting assembly to obtain the casting. It is found through testing that the ceramic cores of the thin-walled casing blades have no deformation, fracture, and no occurrence of any phenomena such as off-center, core leakage, or core breakage.

[0055] Although the present invention has been illustrated and described with specific embodiments, it should be realized that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it; those of ordinary skill in the art should understand that: without departing from the spirit and scope of the present invention, the technical solutions recorded in the foregoing embodiments can be modified, or some or all of the technical features can be equivalently replaced; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present invention; therefore, this means that all such replacements and modifications within the scope of the present invention are included in the appended claims.

Claims

1. A pouring method for a casting of an aero-engine casing, characterized in that, it includes the following steps: Install at least one pouring component in the middle of the support plate of the aero-engine casing, and pour molten metal into the pouring component for bottom gating; The pouring component includes a straight sprue section, a liquid storage pool and a runner; the straight sprue section, the liquid storage pool and the runner are connected in sequence; The ratio of the length of the straight sprue section to the length of the support plate is 0.25 - 0.55; The ratio of the width of the straight sprue section to the wall thickness of the support plate is 1.5 - 2.5; The ratio of the volume of the liquid storage pool to the volume of the straight sprue section is 2.5 - 5.

5.

2. The pouring method for a casting of an aero-engine casing according to claim 1, characterized in that, a liquid passage port is pre-set in the middle of the bottom of the support plate.

3. The pouring method for a casting of an aero-engine casing according to claim 1, characterized in that, The ratio of the length of the straight sprue section to the length of the support plate is 1 / 3 - 1 / 2.

4. The pouring method for a casting of an aero-engine casing according to claim 1, characterized in that, The ratio of the width of the straight sprue section to the wall thickness of the support plate is 2.

5. The pouring method for a casting of an aero-engine casing according to claim 1, characterized in that, The height of the straight sprue section is 3 mm - 15 mm.

6. The pouring method for a casting of an aero-engine casing according to claim 5, characterized in that, The height of the straight sprue section is 5 mm - 10 mm.

7. The pouring method for a casting of an aero-engine casing according to claim 1, characterized in that, The ratio of the volume of the liquid storage pool to the volume of the straight sprue section is 3 - 5.

8. The pouring method for a casting of an aero-engine casing according to claim 1, characterized in that, The ratio of the cross-sectional area of the runner to the cross-sectional area of the liquid storage pool is 1 / 9 - 1 / 5.

9. The pouring method for a casting of an aero-engine casing according to claim 1, characterized in that, The temperature of the bottom gating is 1400 °C - 1700 °C.

10. The pouring method for a casting of an aero-engine casing according to claim 9, characterized in that, The temperature of the bottom gating is 1500 °C - 1600 °C.

11. The pouring method for a casting of an aero-engine casing according to claim 1, characterized in that, Before the bottom gating, preheat the temperature of the mold to 800 °C - 1200 °C.

12. An aero-engine casing prepared by the pouring method for a casting of an aero-engine casing according to any one of claims 1 - 11.

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