Multi-point thermal control feeding method and device for large and complex thin-walled high-temperature alloy castings

Abstract

The application provides a multi-point thermal control feeding method and device for large complex thin-wall high-temperature alloy castings, which comprises the following steps: firstly, classifying all thermal nodes to form the thermal node positions in a sequence from bottom to top as a whole; secondly, based on the classified thermal nodes, preparing a large complex thin-wall casting shell with a complex multi-point thermal control runner by using long strip wax rods; finally, smelting a high-temperature alloy master alloy and pouring it into the large complex thin-wall casting shell; in one or more levels, the long strip wax rods corresponding to the thermal nodes form thermal control pipelines which are connected to the temperature control part, forming a temperature gradient between the thermal nodes at different heights in the same level, so that the thermal node positions in each level are solidified in sequence from bottom to top. The application classifies all thermal nodes for thermal control management, can change the thermal control strength of each level thermal node independently, can reduce the shrinkage cavity and shrinkage porosity formation tendency, and can adjust the grain size of each position of the casting.

Description

Technical Field

[0001] This invention relates to the field of high-temperature alloy precision casting technology, specifically to a multi-point thermal control feeding method and apparatus for large, complex, thin-walled high-temperature alloy castings. Background Technology

[0002] Aero-engines and hypersonic vehicles are crucial national assets, serving as important indicators of a country's comprehensive scientific and technological level, industrial foundation, and capabilities. The development of advanced aero-engines and high-performance hypersonic vehicles has spurred the use of high-temperature alloy castings made from alloys with higher heat-resistant properties. These alloys sometimes contain over 60% heat-strengthening phases, resulting in high porosity, a strong tendency to crack, and extremely poor casting process performance and weldability. Porosity defects and cracks easily occur during the forming process and cannot be repaired by subsequent welding. Simultaneously, structural designs are trending towards larger, more complex, and thinner walls, resulting in numerous heat dissipation points in castings. Interference from these points in the casting and gating systems is a common phenomenon, and coupled with external process disturbances, porosity caused by these heat points exhibits "dynamic behavior." Achieving large-scale forming of extreme-temperature resistant high-temperature alloys with "zero internal porosity" is a key technical challenge in the integrated precision forming of large, complex, thin-walled castings.

[0003] A literature search of existing technologies revealed a Chinese invention patent with application number 201811636648.2. The patent describes a method where a high-temperature alloy liquid rises through a riser pipe under inert gas pressure into a preheated mold and fills the cavity; a heater moves downwards at a certain speed, detaching from the mold; and the high-temperature alloy liquid gradually crystallizes and feeds under inert gas pressure and sequential solidification conditions to obtain a dense microstructure. To a certain extent, this method features single-temperature controlled feeding. While it can effectively solve the defect control problem of simple-structure castings, critical aerospace castings often have complex structural features and multiple dispersed heat points. Single-temperature controlled feeding is insufficient to control internal metallurgical defects in large, complex, thin-walled high-temperature castings. Summary of the Invention

[0004] According to the research of this invention, the key to solving porosity control lies in forming a sequential solidification mode at all hot spots, and developing thermal control feeding technology for multiple hot spots is one of the effective ways to solve the problem of metallurgical defect control in key castings of aerospace high-temperature alloys.

[0005] To address the shortcomings of existing single thermal control feeding technology, this invention provides a multi-point thermal control feeding method and apparatus for controlling metallurgical defects in large, complex, thin-walled high-temperature alloy castings.

[0006] In a first aspect, the present invention provides a method for classifying and determining solidification heat points in large, complex, thin-walled castings, comprising:

[0007] S101, based on the designed gating system for large, complex, thin-walled high-temperature alloy castings, calculates the thermophysical properties of the alloy to be poured, imports them into casting simulation software, performs filling and solidification simulation, and extracts hot spots with a high tendency to form shrinkage cavities and porosity.

[0008] S102, all extracted hot spots are divided into N levels from largest to smallest, and the hot spots are divided into n height levels from the top riser of the gating system of the high-temperature alloy large complex thin-walled casting to the bottom of the casting; all hot spots are labeled according to their level and height level, thus dividing all the hot spots of the entire casting into N*n major categories, each major category has x hot spots, forming a solidification hot spot part sequence from bottom to top.

[0009] In one possible embodiment of the present invention: S101, the design-based gating system for large, complex, thin-walled high-temperature alloy castings refers to a gating system for large, complex, thin-walled high-temperature alloy castings designed using conformal design principles.

[0010] In one possible embodiment of the invention: all hot spots are labeled according to their grade and height level, including:

[0011] Each hot spot is represented by a three-digit code, where:

[0012] The first digit represents the level N to which each hot spot belongs;

[0013] The second bit represents the height level n of each hot spot;

[0014] The third digit represents the number of hot spots at different heights in each level, x.

[0015] Using the above method, all hot spots in the entire casting are divided into N*n major categories, with x hot spots in each category. The three codes can be numbers, letters, or any combination of numbers and letters.

[0016] A second aspect of the present invention provides a method for preparing a large, complex, thin-walled casting shell with complex multi-point thermal control channels, comprising:

[0017] S201 adopts a method for classifying and determining solidification hot spots in large, complex, thin-walled castings, which determines the location of solidification hot spots and the average hot spot diameter for each grade, i.e., N different diameter values.

[0018] S202, according to the designed gating system for large, complex, thin-walled high-temperature alloy castings, wax is pressed and risers and sprues are assembled, and wax rods with diameters of N different values ​​are pressed respectively.

[0019] S203, during the process of applying slurry and sanding large, complex thin-walled castings, the above-mentioned wax rods are connected to the hot joints with the same diameter. Hot joints of the same level are connected with wax rods of the same diameter. After applying slurry and sanding, sealing and drying, the castings are fired to obtain a large, complex thin-walled casting shell with complex multi-point thermal control channels.

[0020] A third aspect of the present invention provides a multi-point thermal controlled feeding method for large, complex, thin-walled high-temperature alloy castings, comprising:

[0021] S301, a high-temperature alloy master alloy, is melted and poured into the above-mentioned large, complex, thin-walled shell after reaching the designed casting temperature.

[0022] S302, in one or more grades, the heat control pipe formed by the long strip wax rod corresponding to the hot spot is connected to the temperature control unit to form a temperature gradient between hot spots of different heights in the same grade, so that solidification is carried out in the order of the hot spot parts in each grade from bottom to top.

[0023] The present invention utilizes the above method to achieve controlled solidification of all hot spots in large, complex, thin-walled castings, forming a bottom-up sequential solidification mode and a multi-point thermal control feeding technology, which can significantly reduce the tendency of shrinkage cavities and porosity formation and improve the overall quality of large, complex, thin-walled high-temperature alloy castings.

[0024] A fourth aspect of the present invention provides a multi-point thermal control feeding device for large, complex, thin-walled high-temperature alloy castings, comprising:

[0025] A gating and spruing system is provided with a riser and a sprue, wherein the riser is located above the sprue;

[0026] Multiple hot spots are divided into N levels from largest to smallest. The hot spots are further divided into n height levels from the top riser to the bottom of the casting, thus dividing all the hot spots in the casting into N*n major categories. Each major category has x hot spots, forming a solidification hot spot section from the bottom of the casting to the riser in a bottom-up sequence.

[0027] At least one long strip wax rod connects to heat nodes of the same level but different heights in N levels of heat nodes, and each long strip wax rod forms a thermal control pipeline;

[0028] The temperature control unit controls the formation of the required temperature gradient among the N levels of hot sections at different heights of the same level through each of the aforementioned thermal control pipelines.

[0029] Compared with the prior art, the embodiments of the present invention have at least one of the following beneficial effects:

[0030] The multi-point thermal control feeding method and apparatus for large, complex, thin-walled high-temperature alloy castings provided in this invention, compared with existing thermal control feeding technologies, not only performs graded thermal control management of all hot spots, but also can isolate and change the thermal control intensity of each level of hot spot. Therefore, it can not only reduce the tendency of shrinkage cavities and porosity to form, but also adjust the grain size of each part of the casting. These advantages are unmatched by traditional thermal control feeding techniques.

[0031] The multi-point thermal control feeding method and apparatus for large, complex, thin-walled high-temperature alloy castings provided in this invention can solve the problem of metallurgical defect control in key high-temperature alloy castings for aerospace applications, aiming to provide support for the high-quality development of key aerospace castings and also provide technical means for energy conservation and emission reduction in the traditional casting industry. Attached Figure Description

[0032] Other features, objects, and advantages of the present invention will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings:

[0033] Figure 1 This is a schematic diagram of multi-point thermal control and shrinkage compensation of grade A in one embodiment of the present invention;

[0034] Figure 2 This is a schematic diagram of multi-point thermal control and shrinkage compensation of grade B in one embodiment of the present invention;

[0035] Figure 3 This is a schematic diagram of multi-point thermal control and shrinkage compensation of grade C among the three grades of thermal sections in one embodiment of the present invention;

[0036] In the diagram: 1 is the riser, 2 is the elongated wax rod ΦAx, 3 is the AGx hotspot, 4 is the AZx hotspot, 5 is the sprue, 6 is the ADx hotspot, 7 is the air compressor, 8 is the elongated wax rod ΦBx, 9 is the BGx hotspot, 10 is the BZx hotspot, 11 is the BDx hotspot, 12 is the elongated wax rod ΦCx, 13 is the CGx hotspot, 14 is the CZx hotspot, and 15 is the CDx hotspot. Detailed Implementation

[0037] The present invention will now be described in detail with reference to specific embodiments. These embodiments will help those skilled in the art to further understand the present invention, but do not limit the invention in any way. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention. These all fall within the scope of protection of the present invention.

[0038] In existing technologies, most thermal control feeding for high-temperature alloy castings employs a single thermal control feeding technique. While this can effectively address defect control in simple casting structures, it is insufficient for large, complex, thin-walled high-temperature alloy castings, especially critical aerospace castings, which often exhibit complex structural features and multiple dispersed heat points. A single thermal control feeding method is therefore inadequate for controlling internal metallurgical defects in these large, complex, thin-walled high-temperature castings. To address these issues, this invention provides a multi-point thermal control feeding method and corresponding apparatus for large, complex, thin-walled high-temperature alloy castings, which will be described in detail below.

[0039] In one embodiment of the present invention, a method for classifying and determining solidification hot spots in large, complex, thin-walled castings is provided, comprising:

[0040] S101, based on the designed gating system for large, complex, thin-walled high-temperature alloy castings, calculates the thermophysical properties of the alloy to be poured, imports them into casting simulation software, performs filling and solidification simulation, and extracts hot spots with a high tendency to form shrinkage cavities and porosity.

[0041] S102, all extracted hot spots are divided into N levels from largest to smallest, and the hot spots are divided into n height levels from the top riser of the gating system of the high-temperature alloy large complex thin-walled casting to the bottom of the casting; all hot spots are labeled according to their level and height level, thus dividing all the hot spots of the entire casting into N*n major categories, each major category has x hot spots, forming a solidification hot spot part sequence from bottom to top.

[0042] The embodiments of the present invention determine the solidification hot spot locations through the above method, and manage all hot spots in a hierarchical and grouped manner, forming a solidification hot spot location sequence from bottom to top, which is beneficial for subsequent multi-point thermal control and shrinkage compensation.

[0043] In the above embodiments, when performing S101, the conformal design principle can be used to design the gating system for large, complex, thin-walled high-temperature alloy castings. Of course, other methods can also be used in other embodiments.

[0044] In some preferred embodiments, during S102, all hot spots are labeled according to their grade and height level. A three-digit code can be used to represent each hot spot, where: the first digit represents the grade N of each hot spot; the second digit represents the height level n of each hot spot; and the third digit represents the number x of hot spots at different height levels within each grade. Using this method, all hot spots in the entire casting are divided into N*n categories, with x hot spots in each category. For example, all hot spots can be divided into N grades from largest to smallest, labeled A, B, C…; and into n height levels from the top riser to the bottom of the casting, labeled G, Z, D…; and labeled according to grade and height level as AGx, AZx, ADx; BGx, BZx, BDx; CGx, CZx, CDx, and so on, where x represents the quantity. Using this method, all hot spots in the entire casting are divided into N*n categories, with x hot spots in each category. This labeling method facilitates the hierarchical classification and thermal control management of all hot sections, and allows for the isolated modification of the thermal control intensity of each hot section level during subsequent thermal control and compensation. Of course, the above is merely a preferred embodiment of the invention; other labeling methods may be used in other embodiments, primarily to distinguish between hot sections of different levels and heights, and are not limited to the above-described implementation.

[0045] In one embodiment, S102 further includes calculating the average hot spot diameters of N levels respectively, for subsequent design of large, complex thin-walled casting shells with complex multi-point thermal control channels.

[0046] Based on the above embodiments, in another embodiment of the present invention, a method for preparing a large, complex, thin-walled casting shell with complex multi-point thermal control channels is also provided, comprising:

[0047] S201, adopts the method for classifying and determining solidification hot spots in large, complex, thin-walled castings, to determine the location of solidification hot spots and the average hot spot diameter of each level, i.e., N different diameter values; wherein, the method for classifying and determining solidification hot spots in large, complex, thin-walled castings can adopt the method described in S101-S102.

[0048] S202, according to the designed gating system for large, complex, thin-walled high-temperature alloy castings, wax is pressed and risers and sprues are assembled, and wax rods with diameters of N different values ​​are pressed respectively; the wax rods can be long strips, for example, wax rods with a length of 300mm are pressed using a mold, which is convenient for subsequent winding, connection and cutting.

[0049] S203, during the process of applying slurry and sanding large, complex thin-walled castings, the above-mentioned wax rods are connected to the hot joints with the same diameter. Hot joints of the same level are connected with wax rods of the same diameter. After applying slurry and sanding, sealing and drying, the castings are fired to obtain a large, complex thin-walled casting shell with complex multi-point thermal control channels.

[0050] In this embodiment, based on the classification of multiple hot spots in large, complex, thin-walled high-temperature alloy castings, a large, complex, thin-walled casting shell with complex multi-point thermal control channels can be obtained by using specific wax rods to connect these classified hot spots in a specific way.

[0051] In some embodiments, in S201, all hot spots are divided into N levels from largest to smallest, labeled A, B, C...; the hot spots are divided into n height levels from the top riser to the bottom of the casting, labeled G, Z, and D...; all hot spots are labeled according to level and height level, namely AGx, AZx, ADx...; BGx, BZx, BDx...; CGx, CZx, CDx..., and so on, where x represents the quantity; the average diameter of the hot spots of the N levels is ΦA, ΦB, ΦC...; then in S202, long strip wax rods with diameters of ΦAx, ΦBx, ΦCx... are pressed.

[0052] In some embodiments, in S203, the large, complex, thin-walled casting undergoes slurry application and sand application. When the slurry reaches a designated layer: ΦA long strip wax rods ΦAx are used to connect all the hot joints of different heights in the first level (AGx, AZx, ADx...); ΦB long strip wax rods ΦBx are used to connect all the hot joints of different heights in the second level (BGx, BZx, BDx...); ΦC long strip wax rods ΦCx are used to connect all the hot joints of different heights in the third level (CGx, CZx, CDx...); following the above method, the connection of long strip wax rods of corresponding diameters between all N levels of hot joints of different heights is completed; slurry application and sand application continue until a set number of layers are reached, and after sealing and drying, a firing treatment is performed to obtain a large, complex, thin-walled casting shell with complex multi-point thermal control channels. In this embodiment, the designated layer refers to the slurry layer of the large, complex, thin-walled casting shell suitable for temperature control measures; the set number of layers refers to the final number of slurry layers of the large, complex, thin-walled casting shell.

[0053] Based on the above embodiments, in another embodiment of the present invention, a multi-point thermal control feeding method for large, complex, thin-walled high-temperature alloy castings is also provided, comprising:

[0054] S301, after melting the high-temperature alloy master alloy and reaching the designed pouring temperature, is poured into a large, complex, thin-walled shell; wherein, the large, complex, thin-walled shell is a large, complex, thin-walled casting shell with complex multi-point thermal control channels obtained from S201 to S203 above.

[0055] S302, subsequently in one or more grades, the thermal control pipe formed by the long strip wax rod corresponding to the hot spot is connected to the temperature control unit, forming a temperature gradient between hot spots of different heights in the same grade, thereby solidifying in the order of the hot spot parts in each grade from bottom to top.

[0056] In this step, thermal control and shrinkage can be performed on one or more thermal sections of different levels according to actual needs to obtain results that meet design requirements.

[0057] In this embodiment, the thermal control pipeline is a long strip-shaped pipeline formed by melting a long strip of wax. The wax is soft and can be woven arbitrarily. After weaving, a paste is applied to cover the long strip of wax. After dewaxing in a dewaxing kettle, a thermal control pipeline identical to the long strip of wax is naturally formed. Therefore, the thermal control pipeline is hollow, with both ends connected to the outside, allowing the introduction of gas or magnesium powder.

[0058] In some preferred embodiments, in S302, the air compressor outlet can be connected to the bottom of the thermal control pipeline formed by the long strip wax rod ΦAx of the first level A thermal section, forcibly forming a temperature gradient from ADx through AZx to AGx..., reducing the probability of shrinkage porosity.

[0059] In some preferred embodiments, in S302, an opening can be formed at the bottom of the thermal control pipeline of the second-level B thermal section BDx. By utilizing the principle of hot air flowing from bottom to top, a temperature gradient is automatically formed from BDx through BZx to BGx..., reducing the probability of shrinkage cavities and porosity.

[0060] In some preferred embodiments, in S302, magnesium powder can be added to the top of the thermal control pipeline of the third level C thermal section CGx. The principle of magnesium powder heating is used to add to the temperature gradient from CDx through CZx to CGx..., thereby reducing the probability of shrinkage cavities and porosity.

[0061] In this embodiment, the addition of magnesium powder causes the upper magnesium powder to burn violently, releasing a large amount of heat, which in turn increases the temperature of the lower part, effectively increasing the temperature gradient from bottom to top, thus promoting sequential solidification from bottom to top. The size of hot spots in different parts of a large, complex, thin-walled casting is relative during the solidification process; comparing the size of hot spots on different castings is meaningless. In engineering, a solidification simulation is first performed on a specific casting. In this embodiment, hot spots are categorized and controlled into three levels: large, medium, and small. Large hot spots are cooled by enhanced airflow using a compressor; medium hot spots rely on their own high-temperature gas flow; and small hot spots are treated with magnesium powder to increase the temperature difference, thereby increasing their respective sequential solidification tendencies. Of course, in other embodiments, any of the above-mentioned temperature gradient controls can be used to better reduce the probability of shrinkage cavities and porosity.

[0062] The above embodiments of the present invention form a bottom-up sequential solidification mode and a multi-point thermal control feeding technology, which can significantly reduce the tendency of shrinkage cavities and porosity and improve the overall quality of large, complex, thin-walled high-temperature alloy castings.

[0063] To implement the aforementioned multi-point thermal control feeding method for large, complex, thin-walled high-temperature alloy castings, another embodiment of the present invention also provides a multi-point thermal control feeding device for large, complex, thin-walled high-temperature alloy castings, which can be referred to... Figure 1-3 It includes: a gating and sprue system, multiple hot spots, at least one long strip wax rod, and a temperature control unit, wherein:

[0064] The gating system includes risers and a sprue, with the risers located above the sprue.

[0065] Multiple hot spots are divided into N levels from largest to smallest, and then into n height levels from the top riser to the bottom of the casting. This results in N*n major categories, with x hot spots in each category, forming a solidification hot spot sequence from the bottom of the casting to the riser. The specific classification method is described in the previous embodiment.

[0066] At least one long strip wax rod connects heat nodes of different heights within the same heat node class of N heat nodes. Each long strip wax rod forms a thermal control pipeline. There can be multiple long strip wax rods, each corresponding to a heat node class. The length of each long strip wax rod is selected according to the height distribution of the heat nodes in that class, and it can connect all heat node parts in that class.

[0067] The temperature control unit controls the formation of the required temperature gradient among N levels of hot sections at different heights within the same category, via each thermal control pipeline. The temperature control unit primarily regulates temperature and can be implemented using an air compressor connected to the thermal control pipeline. Alternatively, in some embodiments, magnesium powder can be added to the thermal control pipeline.

[0068] For a better explanation of the above technical solutions, please refer to [reference needed]. Figure 1-3 In the embodiment described above, all thermal points are divided into three levels and three height levels. The following detailed description of the implementation of the multi-point thermal control feeding method for large, complex, thin-walled high-temperature alloy castings is based on the accompanying drawings.

[0069] First, a method for classifying and determining solidification hot spots in large, complex, thin-walled castings was adopted to determine the classification of all hot spots.

[0070] The gating system for large, complex, thin-walled high-temperature alloy castings was designed using conformal design principles. The thermophysical properties of the alloy to be cast were calculated using thermodynamic calculation software and then imported into casting simulation software for filling and solidification simulation. Hot spots with a high tendency to form shrinkage cavities and porosity were extracted.

[0071] These hot spots were divided into three levels, A, B, and C, from largest to smallest, and the average hot spot diameters were calculated as ΦA, ΦB, and ΦC, respectively. The hot spots were also divided into three height levels from the top riser (1) to the bottom of the casting, labeled G, Z, and D, respectively. All hot spots were then labeled as AGx (3), AZx (4), ADx (6); BGx (9), BZx (10), BDx (11); CGx (13), CZx (14), and CDx (15), where x represents the number. Using this method, all hot spots in the entire casting were divided into 9 categories, with x hot spots in each category. This bottom-up, sequential classification and management of solidification hot spots is beneficial for subsequent multi-point thermal control and feeding.

[0072] Secondly, prepare large, complex thin-walled casting shells with complex multi-point thermal control flow channels;

[0073] According to the conformal design of the gating system, wax is pressed and the riser (1) and sprue (5) are assembled, and long strip wax rods with diameters of ΦA, ΦB and ΦC are pressed into the formwork, ΦAx (2), ΦBx (8) and ΦCx (12).

[0074] Large, complex, thin-walled castings are subjected to slurry application and sand rinsing. When the slurry application reaches the fourth layer, ΦA long strip wax rods ΦAx(2) are used to connect all AGx(3), AZx(4) and ADx(6); ΦB long strip wax rods ΦBx(8) are used to connect all BGx(9), BZx(10) and BDx(11); and ΦC long strip wax rods ΦCx(12) are used to connect all CGx(13), CZx(14) and CDx(15). Slurry application and sand rinsing are continued until the seventh layer. After sealing and drying, the castings are fired to obtain a large, complex, thin-walled casting shell with complex multi-point thermal control channels.

[0075] In this embodiment, when the slurry is applied to the fourth layer, the local shell has sufficient thickness and strength to withstand the impact of the high-temperature melt without breaking. Therefore, in engineering practice, pre-embedded thermocouples and external temperature control measures are generally implemented after the fourth shell layer is completed. Furthermore, the number of shell layers in high-temperature alloy precision casting is related to the size and complexity of the casting. Generally, small castings require 4-7 shell layers, while large, complex, thin-walled castings require 7-12 layers of slurry. As the requirements for the internal quality of castings increase, local temperature control of the casting is necessary. To improve the temperature control effect, in some embodiments, the number of shell layers is often reduced to 7.

[0076] Finally, multi-point thermal control feeding was performed on large, complex, thin-walled high-temperature alloy castings.

[0077] After melting the high-temperature alloy master alloy to the designed casting temperature, it is poured into a large, complex, thin-walled shell; subsequently:

[0078] An air compressor (7) outlet is connected to the bottom of the thermal control pipeline formed by the long strip wax rod ΦAx (2), which forces the formation of a temperature gradient from ADx (6) through AZx (4) to AGx (3), reducing the probability of shrinkage and porosity.

[0079] Similarly, an opening is formed at the bottom of the heat control pipeline of the long strip wax rod ΦBx(8). By utilizing the principle of hot air flowing from bottom to top, a temperature gradient is automatically formed from BDx(11) through BZx(10) to BGx(9), reducing the probability of shrinkage and porosity.

[0080] Similarly, magnesium powder is added to the top of the thermal control pipeline of the long strip wax rod ΦCx(12). The heating principle of magnesium powder is used to add it to the temperature gradient from CDx(15) through CZx(14) to CGx(13), thereby reducing the probability of shrinkage cavities and porosity.

[0081] The above-mentioned symbols for hot spots are merely a representation and are not intended to limit the technical solution.

[0082] This embodiment, through the above operations, enables controlled solidification of all hot spots in large, complex, thin-walled castings, forming an overall bottom-up sequential solidification pattern and a multi-point thermal control feeding technology. This significantly reduces the tendency for shrinkage cavities and porosity to form, improving the overall quality of large, complex, thin-walled high-temperature alloy castings. Furthermore, grain size, or grain density, is closely related to the cooling rate. Increasing the compressor gas flow rate leads to a higher cooling rate and a shorter grain growth time, thus reducing the grain size.

[0083] Based on the above embodiments, the application process will be described in detail below with reference to specific large, complex, thin-walled high-temperature alloy castings.

[0084] Example 1:

[0085] A circular aero-engine casing casting, precision formed from K4169 high-temperature alloy, has a diameter of 1760mm, a height of 370mm, and a minimum wall thickness of 2.4mm.

[0086] First, the gating system for large, complex, thin-walled high-temperature alloy castings was designed using conformal design principles. Thermophysical properties of the alloy to be cast were calculated using thermodynamic calculation software and imported into casting simulation software for filling and solidification simulation. Hot spots with a high tendency to form shrinkage cavities and porosity were extracted. These hot spots were divided into three levels (A, B, and C) from largest to smallest, with average hot spot diameters calculated to be Φ12mm, Φ6mm, and Φ3mm, respectively. The hot spots were then divided into three height levels from the top riser to the bottom of the casting. Do not mark them as 400mm, 200mm, and 100mm. Mark all hot spots according to the above method, namely Φ12mm / 400mm, Φ12mm / 200mm, Φ12mm / 100mm; Φ6mm / 400mm, Φ6mm / 200mm, Φ6mm / 100mm; Φ3mm / 400mm, Φ3mm / 200mm, Φ3mm / 100mm. Due to the overall annular symmetrical structure of the casing casting, there are 12 of each of the above hot spots.

[0087] Secondly, wax is pressed and risers and sprues are assembled according to the conformal gating system. Twelve long wax rods with diameters of Φ8mm, Φ5mm and Φ3mm are pressed. Large, complex, thin-walled castings are then coated with slurry and sand. When the slurry is coated to the fourth layer, Φ8mm long wax rods are used to connect all Φ12mm / 400mm, Φ12mm / 200mm and Φ12mm / 100mm; Φ5mm long wax rods are used to connect all Φ6mm / 400mm, Φ6mm / 200mm and Φ6mm / 100mm; and Φ3mm long wax rods are used to connect all Φ3mm / 400mm, Φ3mm / 200mm and Φ3mm / 100mm. The coating and sanding process continues to the seventh layer. After sealing and drying, the casting is fired to obtain a large, complex, thin-walled casting shell with complex multi-point heat-controlled flow channels.

[0088] Finally, the high-temperature alloy master alloy is melted and poured into a large, complex, thin-walled shell after reaching the designed casting temperature. Then, an air compressor outlet is connected to the bottom of a Φ12mm heat control pipe formed by a long, thin wax rod, forcibly creating a temperature gradient from Φ12mm / 100mm through Φ12mm / 200mm to Φ12mm / 400mm, reducing the probability of shrinkage cavities and porosity. An opening is formed at the bottom of the Φ6mm heat control pipe, utilizing the principle of hot air flowing from bottom to top to automatically create a temperature gradient from Φ6mm / 100mm through Φ6mm / 200mm to Φ6mm / 400mm, further reducing the probability of shrinkage cavities and porosity. Magnesium powder was added to the top of the Φ3mm thermal control pipeline. Utilizing the heating principle of magnesium powder, it was added to the temperature gradient from Φ3mm / 100mm through Φ3mm / 200mm to Φ3mm / 400mm, reducing the probability of shrinkage cavities and porosity. A total of 12 thermal control systems were implemented to achieve controlled solidification of all hot spots in the large, complex, thin-walled casing casting. An overall bottom-up sequential solidification mode was formed, establishing a multi-point thermal control feeding technology. This significantly reduced the tendency of shrinkage cavities and porosity to form, meeting the technical requirements and successfully delivering the casting to a user unit.

[0089] Example 2:

[0090] A certain aerospace thin-walled high-temperature alloy casting, precision-formed using rare-earth high-temperature alloy, is 900mm long, 60mm high, and 1.5mm thick, belonging to a trapezoidal large-area thin-walled component. First, the gating system for this large, complex, thin-walled high-temperature alloy casting was designed using conformal design principles. Thermodynamic calculation software was used to calculate the thermophysical properties of the alloy to be cast, which were then imported into casting simulation software for filling and solidification simulation. Hot spots with a high tendency to form shrinkage cavities and porosity were extracted. Due to the relatively simple overall structure of the casting, there are only two types of hot spots, with calculated average diameters of Φ10mm and Φ3mm. The hot spots are divided into two horizontal heights from the top riser to the bottom of the casting, marked as 900mm and 200mm respectively. All hot spots are labeled as Φ10mm / 900mm, Φ10mm / 200mm; Φ3mm / 900mm, Φ3mm / 200mm, with two of each type.

[0091] The riser and sprue are assembled using a gridded, contour-designed gating system. Two long wax rods with diameters of Φ10mm and Φ3mm are pressed. The trapezoidal, large-area, thin-walled casting is then coated with slurry and sand. When the slurry is applied to the fourth layer, Φ10mm long wax rods are used to connect all Φ10mm / 900mm and Φ10mm / 200mm sections; Φ3mm long wax rods are used to connect all Φ3mm / 900mm and Φ3mm / 200mm sections. The coating and sand application process continues to the seventh layer. After sealing and drying, the casting is fired to obtain a trapezoidal, large-area, thin-walled casting shell with complex multi-point heat-controlled flow channels.

[0092] After melting the rare earth high-temperature alloy master alloy to a casting temperature of 1500±10℃, it is poured into a trapezoidal large-area thin-walled shell preheated to 1050±10℃. Then, an air compressor outlet is connected to the bottom of a Φ10mm long wax rod forming a thermal control pipeline, forcibly creating a temperature gradient from Φ10mm / 200mm to Φ10mm / 900mm, reducing the probability of shrinkage cavities and porosity. Magnesium powder is added to the top of the Φ3mm thermal control pipeline. Utilizing the principle of magnesium powder heating (adding magnesium powder utilizes the heat generated by its combustion to increase the upper temperature, naturally increasing the vertical gradient and thus increasing the tendency for sequential solidification from the bottom to the top of the casting), the temperature gradient from Φ3mm / 200mm to Φ3mm / 900mm is further amplified, reducing the probability of shrinkage cavities and porosity. A total of two thermal control systems achieve controlled solidification of all hot spots in the trapezoidal large-area thin-walled casting, forming an overall sequential solidification pattern from the flat bottom to the top riser, significantly reducing the tendency for shrinkage cavities and porosity, meeting aerospace technology requirements. This demonstrates that the invention is applicable not only to ring-shaped components with symmetrical structures, but also to irregularly shaped components, showcasing its strong versatility.

[0093] Specific embodiments of the present invention have been described above. It should be understood that the present invention is not limited to the specific embodiments described above, and those skilled in the art can make various modifications or variations within the scope of the claims, which do not affect the essence of the present invention. The above preferred features can be used in any combination without conflict.

Claims

1. A method for preparing a large, complex, thin-walled casting shell with complex multi-point thermally controlled flow channels, characterized in that, include: S201, adopts the method of classifying and determining solidification hot spots in large, complex, thin-walled castings, determines the location of solidification hot spots, and the average hot spot diameter of N levels, that is, N different diameter values; The method for classifying and determining solidification heat points in large, complex, thin-walled castings includes: S101, based on the designed gating system for large, complex, thin-walled high-temperature alloy castings, calculates the thermophysical properties of the alloy to be poured, imports them into casting simulation software, performs filling and solidification simulation, and extracts hot spots with a high tendency to form shrinkage cavities and porosity. S102, all extracted hot spots are divided into N levels from largest to smallest, and then further divided into n height levels from the riser at the top of the gating system of the high-temperature alloy large complex thin-walled casting to the bottom of the casting; all hot spots are labeled according to their level and height level, thus dividing all hot spots of the entire casting into N. There are n major categories, and each major category has x hot spots, which together form a solidification hot spot sequence from bottom to top. S202, according to the designed gating system for large, complex, thin-walled high-temperature alloy castings, wax is pressed and risers and sprues are assembled, and wax rods with diameters of N different values ​​are pressed respectively. S203, during the process of applying slurry and sanding large, complex thin-walled castings, the above-mentioned wax rods are connected to the hot joints with the same diameter. Hot joints of the same level but different heights are connected with wax rods of the same diameter. After applying slurry and sanding, sealing and drying, the castings are fired to obtain a shell of a large, complex thin-walled casting with complex multi-point thermal control channels.

2. The method for preparing a large, complex, thin-walled casting shell with complex multi-point thermally controlled flow channels according to claim 1, characterized in that, In S101, the design-based gating system for large, complex, thin-walled high-temperature alloy castings refers to the gating system for large, complex, thin-walled high-temperature alloy castings designed using conformal design principles.

3. The method for preparing a large, complex, thin-walled casting shell with complex multi-point thermally controlled flow channels according to claim 1, characterized in that, In S102, all hot nodes are labeled according to their grade and altitude level, including: Each hot spot is represented by a three-digit code, where: The first digit represents the level N to which each hot spot belongs; The second bit represents the height level n of each hot spot; The third digit represents the number of hot spots at different heights in each level, x. Using the above method, all hot spots in the entire casting are divided into N There are n major categories, and each major category has x hot spots.

4. The method for preparing a large, complex, thin-walled casting shell with complex multi-point thermally controlled flow channels according to claim 1, characterized in that, S102 also includes calculating the average hot spot diameter for N levels, which is used for subsequent design of large, complex thin-walled casting shells with complex multi-point thermal control channels.

5. The method for preparing a large, complex, thin-walled casting shell with complex multi-point thermally controlled flow channels according to claim 1, characterized in that, In S201, all hot spots are divided into N levels from largest to smallest and labeled as A, B, C...; The casting is divided into n height levels from the top riser to the bottom of the casting according to the heat points, and these levels are marked as G, Z, D, etc. All hot spots are labeled according to their grade and height level, namely AGx, AZx, ADx...; BGx, BZx, BDx...; CGx, CZx, CDx..., and so on, where x represents the number; The average hot spot diameters of N grades are ΦA, ΦB, ΦC...; then, in S202, long strip wax rods with diameters of ΦA, ΦB, ΦC... are pressed, with diameters of ΦA, ΦB, ΦC... as follows: ΦAx, ΦBx, ΦCx...

6. The method for preparing a large, complex, thin-walled casting shell with complex multi-point thermally controlled flow channels according to claim 5, characterized in that, In S203, large, complex, thin-walled castings undergo slurry application and sand rinsing. When the slurry reaches a designated layer: A long strip wax rod ΦAx is used to connect all the heat joints of different heights in the first level, AGx, AZx, ADx...; A long strip wax rod ΦBx is used to connect all the heat joints of different heights in the second level, BGx, BZx, BDx...; A long, thin wax rod ΦCx is used to connect the heat joints of different heights in all third-level categories, such as CGx, CZx, CDx, etc. Following the above method, connect all N different levels of hot spots using long strip wax rods of corresponding diameters; Continue applying the slurry and sand to the set number of layers, seal and dry the slurry, and then perform a firing process to obtain a large, complex, thin-walled casting shell with complex multi-point heat-controlled flow channels.

7. A multi-point thermal control feeding method for large, complex, thin-walled high-temperature alloy castings, characterized in that, include: S301, after melting a high-temperature alloy master alloy to reach the designed pouring temperature, is poured into a large, complex, thin-walled casting shell with complex multi-point thermal control channels obtained by any one of claims 1-6. S302, in one or more grades, the heat control pipe formed by the long strip wax rod corresponding to the hot spot is connected to the temperature control unit to form a temperature gradient between hot spots of different heights in the same grade, so that solidification is carried out in the order of the hot spot parts in each grade from bottom to top.

8. The multi-point thermal control feeding method for large, complex, thin-walled high-temperature alloy castings according to claim 7, characterized in that, S302 includes one or more of the following options: In the first level A, the bottom of the thermal control pipeline formed by the long strip wax rod ΦAx of the thermal section is connected to the air compressor outlet, forcibly forming a temperature gradient from ADx through AZx to AGx..., reducing the probability of shrinkage cavities and porosity; and / or, In the second level B, an opening is formed at the bottom of the thermal control pipeline formed by the long strip wax rod ΦBx in the thermal section. Utilizing the principle of hot airflow from bottom to top, a temperature gradient is automatically formed from BDx through BZx to BGx..., reducing the probability of shrinkage cavities and porosity; and / or, In S302, magnesium powder is added to the top of the thermal control pipeline formed by the long strip wax rod ΦCx in the third grade C thermal section. The principle of magnesium powder heating is used to add to the temperature gradient from CDx through CZx to CGx..., reducing the probability of shrinkage cavities and porosity.

9. A multi-point thermal control feeding device for large, complex, thin-walled high-temperature alloy castings, used to implement the multi-point thermal control feeding method for large, complex, thin-walled high-temperature alloy castings as described in claim 7 or 8, characterized in that, include: A gating and spruing system is provided with a riser and a sprue, wherein the riser is located above the sprue; Multiple hot spots are used to divide all the hot spots in the entire casting into N levels from largest to smallest. These hot spots are then divided into n horizontal levels from the top riser to the bottom of the casting, thus dividing the entire casting into N hot spots. There are n major categories, and each major category has x hot spots, forming a solidification hot spot section from the bottom of the casting to the riser in a bottom-up sequence; At least one long strip wax rod connects to heat nodes of the same level but different heights in N levels of heat nodes, and each long strip wax rod forms a thermal control pipeline; The temperature control unit controls the formation of the required temperature gradient among the N levels of hot sections at different heights of the same level through each of the aforementioned thermal control pipelines.

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