Pressure-regulated casting pouring system and method

Abstract

This invention provides a pressure-regulating casting gating system and method, relating to the field of high-temperature alloy precision casting. It includes a first sprue located at the bottom of the mold, connected to a lower annular sprue via a lower horizontal runner; a second sprue located at the top of the mold, coaxial with the first sprue, and connected to the lower horizontal runner; the second sprue is connected to an upper annular sprue and the upper end of an outer ring via an upper first horizontal runner; an inner gate at the lower end of the outer ring is located at the outer ring position of the casting, one end connected to the lower annular sprue, and the other end connected to the bottom of the outer ring of the casting; an inner gate at the lower end of the inner ring is located at the inner ring position of the casting; the second sprue is connected to the upper end of the inner ring of the casting via an upper second horizontal runner. Controlling the inner diameter of the second sprue can improve the filling capacity of the casting. This pressure-regulating casting gating system and method achieves improved filling and feeding capacity of large, complex, thin-walled high-temperature alloy castings without increasing the filling and pressure increase speed.

Description

Technical Field

[0001] This invention relates to the field of high-temperature alloy precision casting technology, and in particular to a pressure-adjusting casting gating system and method. Background Technology

[0002] As the structures of key hot-end components in aero-engines become larger, more integrated, and thinner-walled, the difficulties in filling large, complex, thin-walled castings during forming and solidification, caused by the effects of large size, variable cross-section, and thin walls, have gradually exceeded the limits of traditional gravity casting. Pressure-controlled casting, as an anti-gravity method, overcomes the limitations of traditional gravity casting for thin-walled parts, significantly improving their filling capacity and mechanical properties. However, the gating system, as the most influential factor on casting quality during the casting process, has received few reports on its application in pressure-controlled casting for producing large, complex, thin-walled castings such as engine casings.

[0003] Furthermore, in the process of pressure-controlled precision casting of large, complex, thin-walled castings such as casings using high-temperature alloys, to avoid defects such as incomplete filling and cold shuts, the filling pressure increase rate is generally increased to achieve a faster filling speed and greatly improve the filling capacity. However, the selection of the filling pressure increase rate is objectively constrained by factors such as equipment and mold quality. Further increases in the filling pressure increase rate place higher demands on the equipment; and high filling pressure increase rates also pose a significant challenge to the quality of the mold, making it prone to problems such as mold fire. To date, there is no good solution.

[0004] A search revealed Chinese invention patent application CN115283622A, which discloses a mixed-filling gating system and method for large-size complex annular thin-walled casings. This system allows for sequential filling of castings, reducing the probability of under-casting, air entrapment, shrinkage porosity, and improving forming quality. However, this method focuses on designing a gating system specifically for conventional gravity casting, and is not applicable to pressure-controlled casting. Furthermore, it primarily addresses the feeding problem at hot spots in thin-walled castings, without addressing improvements in filling capacity.

[0005] Chinese invention patent application CN114653924A discloses a low-pressure casting gating system suitable for feeding complex thin-walled castings. This invention solves the problem of difficult arrangement of casting gating systems, resulting in more feeding channels and shorter feeding paths for aluminum alloy castings with complex geometries and thin walls during the casting process. However, in anti-gravity casting, the molten metal fills from bottom to top under the action of pressure difference, which is prone to reverse filling. For high-temperature alloys with a higher density than aluminum alloys, this reverse filling will have a greater impact on the casting quality due to the increase in self-weight. In addition, there are differences between pressure-adjusting casting and low-pressure casting. In pressure-adjusting casting, the back pressure inside the mold shell is lower during the filling process, and the resistance encountered by the molten metal during the filling process is smaller. In contrast, in low-pressure casting, there is a certain back pressure inside the mold cavity. This leads to certain limitations of this invention in filling complex thin-walled high-temperature alloys in pressure-adjusting casting.

[0006] In summary, there is an urgent need to design a pressure-regulating casting scheme for casing castings, so as to improve the filling and feeding capabilities of large, complex, thin-walled high-temperature alloy casing castings without increasing the filling and pressure-boosting speed. Summary of the Invention

[0007] The purpose of this invention is to provide a pressure-regulating casting system and method to solve the problems existing in the prior art, and to improve the filling and feeding capacity of large, complex, thin-walled high-temperature alloy castings without increasing the filling and pressure-boosting speed.

[0008] To achieve the above object, the present invention provides the following solutions:

[0009] This invention provides a pressure-regulating casting gating system, comprising: a first sprue disposed at the lower part of the mold, the first sprue being connected to a lower annular horizontal sprue via a lower horizontal sprue; a second sprue disposed at the upper part of the mold, the second sprue being coaxial with the first sprue and connected to the lower horizontal sprue; the second sprue being connected to an upper annular horizontal sprue and the upper end of an outer ring via an upper first horizontal sprue; an inner gate at the lower end of the outer ring, located at the outer ring position of the casting, one end of which is connected to the lower annular horizontal sprue, and the other end of which is connected to the bottom of the outer ring of the casting; an inner gate at the lower end of the inner ring, located at the inner ring position of the casting, one end of which is connected to the lower annular horizontal sprue, and the other end of which is connected to the bottom of the inner ring of the casting; the second sprue being connected to the upper end of the inner ring of the casting via an upper second horizontal sprue.

[0010] This invention establishes a three-dimensional solid model based on the structure of the casing casting. Its overall structure is relatively complex, with the casting having a double-ring structure and a large number of variable cross-section structures, large areas of thin-walled regions concentrated at the inner and outer rings and hollow support plates, as well as flange structures above and below the inner and outer rings. The casting as a whole is highly rotationally symmetrical. The area of ​​each part of the gating system is calculated, the type of gating system and the pressurization speed are selected, and a traditional pressure regulating gating system is established. Then, by controlling the inner diameter of the second sprue, the position of the molten metal flow and the filling capacity are controlled without increasing the pressurization speed.

[0011] Based on the casting material and casting structure, select the type of gating system, determine the cross-sectional area ratio and number of the sprue, gating runner and ingate of the gating system, and establish a traditional pressure regulating casting gating system.

[0012] Optionally, the diameter of the second sprue is 20 mm.

[0013] Optionally, the diameter of the second sprue is 40 mm.

[0014] Optionally, the diameter of the second sprue is 70 mm. After assembling the gating system with the casting, it is imported into ProCAST numerical simulation software to numerically simulate the filling and solidification processes of castings with different second sprues for comparison. By numerically simulating the filling process of large, complex, thin-walled castings, the fluid analysis module of ProCAST software can simulate all effects of liquid and solid flow, including filling, and couples fluid flow and heat transfer calculations using the complete Navier-Stocks flow equations. Based on the simulation results of the above three-dimensional model, filling time curves and shrinkage porosity curves of different gating systems are plotted at the same pressurization rate.

[0015] Optionally, the inchgate can be located in the thickest part of the casting, which is beneficial for solidification and feeding, and reduces casting defects. Furthermore, in pressure-controlled casting, the size of the inchgate also determines whether the molten metal is filled by jet or uniform flow. Jet flow is more prone to shrinkage defects, but it can improve the filling performance of the casting to some extent. Based on the casting structure, the product of the feeding efficiency of the pressure-controlled casting gating system and the volume of the pressure-controlled casting gating system is greater than the overall shrinkage of the casting and the pressure-controlled casting gating system. The relationship is as follows:

[0016] η×v1>ε×(v2+v1)

[0017] Where η is the feeding efficiency of the pressure-regulating casting gating system; ε is the volume shrinkage rate of the alloy; v1 is the volume of the pressure-regulating casting gating system; v2 is the volume of the casting, and the alloy is a high-temperature alloy solution used for casting.

[0018] Optionally, since high-temperature alloys are easily oxidized metals, the gating system is designed as an open gating system. This results in a low flow velocity of molten metal entering the mold cavity, smooth filling, and prevention of metal oxidation. Simultaneously, the gating system provides sufficient filling metal. The sum of the cross-sectional areas of the ingates is greater than the sum of the cross-sectional areas of the lower runner, the upper first runner, and the upper second runner. The sum of the cross-sectional areas of the lower runner, the upper first runner, and the upper second runner is greater than the sum of the cross-sectional areas of the first sprue and the second sprue. This satisfies the relationship: ∑Aingate > ∑Arunner > ∑Asprue. In the casting process, the ingate refers to the channel that transports molten metal from the sprue or runner to the mold cavity; this is existing technology. It is a key component of the gating system, responsible for accurately and effectively introducing molten metal from the main gate into various parts of the mold to ensure uniform filling and good forming of the casting.

[0019] Optionally, based on relevant casting filling theories, a relatively slow filling speed should be used for thick-walled, simple-structured castings, while a relatively fast filling speed should be selected for thin-walled, complex castings. In this invention, for large, complex, thin-walled castings such as casings, a filling pressure increase rate of 15 kPa / s is adopted. According to Bernoulli's equation, the relationship between the pressure increase rate and the filling speed during pouring is as follows:

[0020]

[0021] In the formula, P(t) is the pressurization rate, t is the filling time, ρ is the alloy density, g is the gravitational acceleration, V is the filling rate of the molten metal, and the molten metal is an alloy molten metal. f -Cross-sectional area of ​​the riser pipe, A F - Cross-sectional area of ​​the crucible used for casting.

[0022] Optionally, based on the casting structure and the three-dimensional model of the traditional pressure-regulating casting gating system, the model is imported into ProCAST numerical simulation software according to the determined gating assembly method to numerically simulate the casting filling and solidification process of the traditional gating system. Based on the design method of the mixed-pour gating system in gravity casting, the three-dimensional model of the traditional pressure-regulating casting gating system is optimized. To enhance filling and shrinkage compensation, an upper gating channel is added to the casing casting, and the dimensions of the second sprue are controlled to control the filling time and shrinkage porosity. The shrinkage porosity content of large, complex, thin-walled castings after solidification is calculated through numerical simulation. ProCAST software uses the Niyama criterion (Ny). Both the Niyama criterion and ProCAST software are existing technologies. The Niyama criterion is widely used in investment casting. The criterion for determining the shrinkage porosity content of the casting after solidification using the Niyama criterion is...

[0023]

[0024] In the formula, G is the temperature gradient and T is the cooling rate.

[0025] The present invention also provides a pressure-adjusting casting method, comprising the following steps:

[0026] Design the inner diameter of the second direct sprue;

[0027] Select the pressurization speed based on the wall thickness and structure of the casting;

[0028] The molten metal is diverted using a second sprue, and the casting is produced by a mixed pouring method that fills the casting from the top and bottom to the middle simultaneously.

[0029] The present invention achieves the following technical effects compared to the prior art:

[0030] This invention optimizes the traditional pressure-regulating casting gating system without altering the pressure increase rate. By controlling the size of the second sprue in the optimized gating system, it controls the filling time and the convergence point of the molten metal, significantly reducing casting defects. Firstly, by using a second sprue connected to the lower runner, the invention diverts the molten metal, employing a mixed-flow pouring method where the casting is simultaneously filled from the top and bottom towards the center. This shortens the overall filling time, reduces the tendency for under-casting, and allows control of the alloy flow position within the casting by adjusting the size of the central column. Controlling the central column size also controls the filling time, enhancing filling capacity at a given pressure increase rate and reducing the requirements for equipment and mold quality. Secondly, risers are provided at the top and bottom of the casting, forming a ring structure fully connected to the gating system. This ensures proper feeding of the casting and effectively transfers thermal stress to the gating system, preventing excessive thermal deformation. Based on these designs, high-quality casting of large-size, complex, annular, thin-walled casings is achieved. Attached Figure Description

[0031] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in 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 paying any creative work.

[0032] Figure 1 A schematic diagram of the structure of castings and pressure-regulating casting gating systems in existing technologies;

[0033] Figure 2 This is a schematic diagram of the casting and the pressure-regulating casting gating system in the prior art from another angle.

[0034] Figure 3 for Figure 1A sectional view;

[0035] Figure 4 This is a schematic diagram of the structure of a casting and gating system according to an embodiment of the present invention;

[0036] Figure 5 for Figure 4 Another perspective illustration;

[0037] Figure 6 for Figure 4 A sectional view;

[0038] Figure 7 This is a schematic diagram of the casting and gating system according to another embodiment of the present invention;

[0039] Figure 8 for Figure 7 Another perspective illustration;

[0040] Figure 9 for Figure 7 A sectional view;

[0041] Figure 10 This is a schematic diagram of the casting and gating system according to the third embodiment of the present invention;

[0042] Figure 11 for Figure 10 Another perspective illustration;

[0043] Figure 12 for Figure 10 Cross-sectional view;

[0044] Figure 13 A schematic diagram comparing the filling time of the mold cavity between the existing gating system and the gating system of the present invention;

[0045] Figure 14 A schematic diagram comparing the shrinkage porosity content after solidification of a prior art gating system and the gating system of the present invention;

[0046] In the figure: 1-casting, 2-gating system, 3-first sprue, 4-lower runner, 5-lower annular runner, 6-inner gate at the lower end of the outer ring, 7-inner gate at the lower end of the inner ring, 8-second sprue, 9-first upper runner, 10-second upper runner, 11-upper annular runner. Detailed Implementation

[0047] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0048] The purpose of this invention is to provide a pressure-regulating casting system and method to solve the problems existing in the prior art, and to improve the filling and feeding capacity of large, complex, thin-walled high-temperature alloy castings without increasing the filling and pressure-boosting speed.

[0049] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0050] This invention provides a pressure-regulating casting gating system, such as... Figure 1 , Figure 2 , Figure 3 As shown, this is the structure of an existing gating system. The figure includes casting 1 and gating system 2 for pouring high-temperature alloy molten metal. Casting 1 is a large, complex, thin-walled casing casting. The overall structure of the thin-walled casing casting is quite complex, consisting of a highly rotationally symmetrical double-ring structure, composed of an inner ring, an outer ring, and a hollow support plate. It contains numerous variable cross-section structures and large thin-walled areas. The main structure of a traditional pressure-regulating casting gating system for pouring high-temperature alloy molten metal includes: a first straight sprue 3, a lower horizontal sprue 4, a lower annular horizontal sprue 5, an inner gate at the lower end of the outer ring 6, and an inner gate at the lower end of the inner ring 7.

[0051] like Figure 4 , Figure 5 , Figure 6 The figure shows the structure of an embodiment of the present invention. The figure includes a large, complex, thin-walled casing casting 1 and a modified and optimized gating system 3 for pouring high-temperature alloy molten metal. The gating system structure mainly includes: a first sprue 3, a lower horizontal sprue 4, a lower annular horizontal sprue 5, an inner gate at the lower end of the outer ring 6, an inner gate at the lower end of the inner ring 7, a second sprue 8 with a diameter of 20 mm, an upper first horizontal sprue 9, an upper second horizontal sprue 10, and an upper annular horizontal sprue 11.

[0052] like Figure 7 , Figure 8 , Figure 9 As shown, in another specific embodiment, the diameter of the second sprue 8 is 40mm.

[0053] like Figure 10 , Figure 11 , Figure 12 As shown, in the third specific embodiment, the diameter of the second straight gating channel 8 is 70mm.

[0054] Based on the casting material and structure, the type of gating system is selected, and the cross-sectional area ratio and number of the sprue, gating system, and ingate are determined to establish a traditional pressure-controlled casting gating system. The ingate (the contact surface between the ingate and the casting) is located in the thicker part of the casting wall, which helps with solidification and feeding, and suppresses casting defects. In pressure-controlled casting, the ingate includes ingate 6 at the lower end of the outer ring and ingate 7 at the lower end of the inner ring. The size of the ingate also determines whether the molten metal is sprayed into the mold, which easily leads to casting defects. According to the casting structure, the product of the feeding efficiency of the pressure-controlled casting gating system and the volume of the pressure-controlled casting gating system is greater than the overall shrinkage of the casting and the pressure-controlled casting gating system, with the relationship: η×v1>ε×(v2+v1).

[0055] In the formula:

[0056] η—feeding efficiency of the pressure-regulating casting gating system; ε—volume shrinkage rate of the alloy; v1—volume of the pressure-regulating casting gating system; v2—volume of the casting.

[0057] Since high-temperature alloys are easily oxidized metals, the gating system is designed as an open gating system. This results in a low flow rate of molten metal entering the mold cavity, smooth filling, and prevention of oxidation of the high-temperature alloy molten metal. At the same time, the gating system can provide sufficient filling metal. The sum of the cross-sectional areas of the ingates is greater than the sum of the cross-sectional areas of the lower runner, the upper first runner, and the upper second runner. The sum of the cross-sectional areas of the lower runner, the upper first runner, and the upper second runner is greater than the sum of the cross-sectional areas of the first sprue and the second sprue. This satisfies the relationship ∑A_ingate > ∑A_runner > ∑A_sprue.

[0058] According to relevant casting filling theories, a relatively slow filling speed should be used for thick-walled, simple-structured castings, while a relatively fast filling speed should be selected for thin-walled, complex castings. In this embodiment, the large, complex, thin-walled casing-type casting is prone to defects such as incomplete filling and cold shuts when filled with high-temperature alloys. However, when the filling pressure is high, the current quality of the mold shell is insufficient. Therefore, in this embodiment, based on practical considerations, a filling pressure of 15 kPa / s is adopted. Under pressure-regulated casting, this invention uses a pressure increase rate of 15 kPa / s. By controlling the second sprue, the filling time can be reduced, shrinkage porosity can be decreased, and even the confluence of molten metal in the casting can be controlled by adjusting the diameter of the second sprue. This avoids confluence at critical locations, enhancing filling capacity. By optimizing the gating system and changing the diameter of the optimized second sprue, the filling and feeding capabilities of the casting can be improved without increasing the pressure.

[0059] According to Bernoulli's equation, the relationship between the pressurization rate and the filling rate can be calculated as follows:

[0060]

[0061] In the formula, P(t) is the pressurization rate, t is the filling time, ρ is the alloy density, g is the gravitational acceleration, V is the filling rate of the molten metal, and A is the alloy density. f -Cross-sectional area of ​​the riser pipe, A F -Cross-sectional area of ​​the crucible.

[0062] Taking the design of the anti-gravity pressure-regulating precision casting gating system for K4800 nickel-based superalloy as an example, the technical solution of this application will be further described in detail. Different pressure increase rates of the molten metal in pressure-regulating casting have different effects on the diameter of the second sprue of the gating system. When the pressure increase rate is below 5 kPa / s, the filling time does not decrease with the increase of the second sprue diameter; in fact, it increases compared to traditional design methods. When the pressure increase rate is above 30 kPa / s, a smaller second sprue diameter can reduce the filling time. However, in general, the filling time can be controlled by adjusting the second sprue. In actual use, the specific pressure increase rate is not limited; a suitable value can be selected according to needs.

[0063] The design method in this embodiment is applicable to large-sized, complex, thin-walled casing castings.

[0064] Figure 1 , Figure 2 , Figure 3 This is a schematic diagram of a traditional pressure-regulating casting gating system and its assembly structure.

[0065] This invention optimizes the traditional pressure-regulating casting gating system by adding a filling and feeding gating system to the upper part of the casting. Simultaneously, the second sprue 8 is controlled at 20mm, 40mm, and 70mm to regulate the filling process and time. Specific parameters involved in the simulation verification are as follows: the filling pressure increase rate is selected as 15kPa / s; the outer ring diameter of casting 1 is 328mm; the inner ring diameter of casting 1 is 168mm; and the overall height of the casting is 105mm.

[0066] The time required for complete filling of castings under different gating systems was statistically analyzed, such as... Figure 13As shown, it can be observed that for traditional gating systems, the filling time for the complete filling of the mold cavity by the molten alloy is relatively low, at 1.53s, but the castings have more defects such as shrinkage porosity and shrinkage cavities. The optimized and improved Gating System No. 1, due to its increased volume, requires more molten metal to fill the mold, thus increasing the filling time to 2.84s, but significantly reducing defects such as shrinkage porosity and shrinkage cavities. Further increasing the size of the second sprue to 40mm results in the improved Gating System No. 2, whose filling time is drastically reduced compared to the system with a 20mm second sprue, and not significantly different from the traditional system, at 1.67s. Building on this, further increasing the size of the second sprue to 70mm results in the improved Gating System No. 3, which has the fastest filling time of 1.31s compared to the previous systems. It can be observed that at the same filling pressure increase rate, the filling time decreases significantly with the increase in the size of the second sprue. Therefore, by controlling the size of the second sprue of the optimized pressure-regulating casting gating system, the filling speed of large, complex, thin-walled casing castings can be controlled, and simulation results show that it can also control the location of the molten metal confluence.

[0067] In addition, statistics were compiled on shrinkage porosity and shrinkage cavity defects that occurred in castings after filling and solidification under different gating systems, such as... Figure 14 As shown, it can be observed that, on the one hand, the optimized gating system significantly reduces the content of shrinkage porosity and shrinkage cavities compared to the unoptimized gating system, thus improving the quality of the casting; on the other hand, the defect content between gating systems of different sizes of second sprues is not significantly different, simply showing a trend of first increasing and then decreasing.

[0068] In summary, the modified design method of the gating system in this embodiment of the invention effectively solves the shortcomings of traditional design methods. For large-sized, complex, thin-walled casing castings, the gating system designed using the method of this embodiment of the invention can rapidly fill the mold with molten metal while significantly reducing casting defects.

[0069] The above embodiments are illustrated using the design of a precision casting gating system for anti-gravity pressure regulating casting as an example. Based on the traditional design of the anti-gravity precision casting gating system, and according to the design method of the mixed-pouring gating system in gravity casting, the traditional gating system of pressure regulating casting is optimized. By adjusting the size of the second sprue of the optimized gating system, the purpose of controlling the movement and properties of large-sized complex thin-walled casing castings is achieved.

[0070] The gating system design method in this invention is applicable to anti-gravity casting processes such as low-pressure casting, differential pressure casting, and pressure-adjusting casting; it can be used for various casting materials such as cast iron, cast steel, aluminum alloys, magnesium alloys, copper alloys, titanium alloys, and nickel-based high-temperature alloys. The gating system design method in the above embodiments can more rationally improve the filling capacity and provide casting forming quality without increasing the filling and pressurization speed.

[0071] Specific examples have been used to illustrate the principles and implementation methods of this invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of this invention. Furthermore, those skilled in the art will recognize that, based on the ideas of this invention, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of this invention.

Claims

1. A pressure-regulating casting gating system, characterized in that: include: The first sprue is located at the bottom of the mold and is connected to the lower annular sprue via the lower horizontal runner. The second sprue is located on the upper part of the mold. The second sprue is coaxial with the first sprue and is connected to the lower runner. The second sprue is connected to the upper annular runner and the upper end of the outer ring of the casting through the upper first runner. The inner gate at the lower end of the outer ring is located at the outer ring position of the casting, with one end connected to the lower annular horizontal runner and the other end connected to the bottom of the outer ring of the casting; The inner gate at the lower end of the inner ring is located at the inner ring position of the casting. One end of the inner gate at the lower end of the inner ring is connected to the lower horizontal runner, and the other end is connected to the bottom of the inner ring of the casting. The second sprue connects to the upper end of the inner ring of the casting via the upper second sprue; The product of the feeding efficiency of the pressure-regulating casting gating system and the volume of the pressure-regulating casting gating system is greater than the overall shrinkage of the casting and the pressure-regulating casting gating system. The relationship is as follows: η×v1>ε×(v2+v1) Where η is the feeding efficiency of the pressure-regulating casting gating system; ε is the volume shrinkage rate of the alloy; v1 is the volume of the pressure-regulating casting gating system; v2 is the volume of the casting. The sum of the cross-sectional areas of the ingates is greater than the sum of the cross-sectional areas of the lower runner, the upper first runner, and the upper second runner; the sum of the cross-sectional areas of the lower runner, the upper first runner, and the upper second runner is greater than the sum of the cross-sectional areas of the first sprue and the second sprue. These conditions satisfy the following relationship: ∑A 内浇道 >∑A 横浇道 >∑A 直浇道 ; The relationship between the pressurization rate and the filling rate during casting is as follows: In the formula, P(t) is the pressurization rate, t is the filling time, ρ is the alloy density, g is the gravitational acceleration, V is the filling rate of the molten metal, and A is the alloy density. f -Cross-sectional area of ​​the riser pipe, A F -Cross-sectional area of ​​the crucible; The Niyama criterion is used to determine the shrinkage porosity content of a casting after solidification. In the formula, G is the temperature gradient and T is the cooling rate; The three-dimensional model of the traditional gating system for pressure-regulating casting is optimized. In order to enhance filling and shrinkage compensation, an upper gating system for the casing casting is added, and the size of the second sprue is controlled to control the filling time and shrinkage porosity.

2. The pressure-regulating casting gating system according to claim 1, characterized in that: The diameter of the second direct sprue is 20mm.

3. The pressure-regulating casting gating system according to claim 1, characterized in that: The diameter of the second sprue is 40mm.

4. The pressure-regulating casting gating system according to claim 1, characterized in that: The diameter of the second sprue is 70mm.

5. The pressure-regulating casting method of the pressure-regulating casting gating system according to any one of claims 1 to 4, characterized in that: Includes the following steps: Design the inner diameter of the second direct sprue; Select the pressurization speed based on the wall thickness and structure of the casting; The molten metal is diverted using a second sprue, and the casting is produced by a mixed pouring method that fills the casting from the top and bottom to the middle simultaneously.

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