Investment casting cooling device and cooling method thereof

Abstract

The invention provides an investment casting cooling device and a cooling method thereof, and relates to the technical field of investment casting cooling, the investment casting cooling device comprises a corrugated pipe, the corrugated pipe can be arranged according to a hot spot area or a key cooling area of a casting, the flow direction of a cooling medium can be well controlled through the corrugated pipe, so that the area needing to be cooled is controlled, and the cooling efficiency is improved. And the air outlet in the corrugated pipe deviates from the pouring gate, so that the pouring gate is effectively prevented from being cooled, feeding can be more effectively carried out, and the technical problems that in the prior art, the action range of liquid nitrogen airflow flowing at a high speed is difficult to accurately control, and a feeding pouring gate system is inevitably affected while a casting body is cooled are solved.

Description

Technical Field

[0001] This invention relates to the field of investment casting cooling technology, and in particular to an investment casting cooling device and cooling method. Background Technology

[0002] Investment casting of aluminum alloys is an important metal forming process with wide applications in aerospace, automotive manufacturing, and other fields. Traditional investment casting of aluminum alloys typically uses air cooling or water cooling, but these methods suffer from uneven cooling rates and the potential for shrinkage defects within the casting. In recent years, to improve casting performance, liquid nitrogen rapid cooling technology has been introduced into the field of investment casting of aluminum alloys. Liquid nitrogen has an extremely low boiling point (-196℃) and extremely high latent heat of vaporization, enabling ultra-rapid cooling of castings, significantly refining the grain structure and improving mechanical properties. In practice, liquid nitrogen is directly sprayed onto the surface of the casting through a specialized nozzle system, utilizing its phase change endothermic principle to remove a large amount of heat.

[0003] However, this cooling method has an inherent drawback: the high-speed flow of liquid nitrogen is difficult to precisely control its effective range, and while cooling the casting itself, it inevitably affects the feeding gating system. Because the feeding channels cool and solidify prematurely, the feeding of the molten metal is hindered, which in turn increases the risk of shrinkage cavities inside the casting. This contradicts the original intention of the rapid cooling process to improve casting quality. Summary of the Invention

[0004] The purpose of this invention is to provide a cooling device and method for investment castings, so as to alleviate the technical problem in the prior art that it is difficult to accurately control the effective range of high-speed liquid nitrogen gas flow, and that while cooling the casting body, it inevitably affects the feeding and gating system.

[0005] In a first aspect, the investment casting cooling device provided by the present invention includes: a bellows; The bellows is configured to be arranged in the hot spot region of the casting; The corrugated pipe has multiple air outlets along its length. The air outlets are directed towards the casting and away from the gating system. The corrugated pipe is used to deliver the cooling medium to the casting through the multiple air outlets.

[0006] In an optional implementation, The investment casting cooling device also includes a storage tank; The storage tank is used to store the cooling medium, and one end of the bellows is connected to the storage tank; One or more corrugated pipes are provided, and all of the corrugated pipes are connected to the storage tank.

[0007] In an optional implementation, A flow check valve is provided at one end of the bellows near the storage tank. The flow check valve is used to control the flow of cooling medium from the storage tank into the bellows.

[0008] In an optional implementation, A flow control valve is provided at the end of the bellows away from the storage tank. The flow control valve is used to control the flow rate of the cooling medium in the bellows in order to control the flow rate of the air outlet.

[0009] Secondly, the cooling method based on the investment casting cooling device provided by the present invention includes the following cooling steps: Determine the hot-bonding location of the casting and arrange a bellows at the hot-bonding location. The air outlet of the bellows should face the hot-bonding location, and the air outlet direction of the bellows should be away from the gating system.

[0010] In an optional implementation, It also includes the shell-making step: Make wax models and assemble them into modules; The module is coated with paint to create a shell, thus completing the shell-making process. After the shell is made, it is dewaxed and fired to form the required mold shell.

[0011] In an optional implementation, It also includes the bellows manufacturing process: Cut the bellows for cooling according to the size of the casting; Multiple air vents are formed by making holes at regular intervals on the corrugated pipe.

[0012] In an optional implementation, It also includes assembly steps: The number of bellows is determined according to the casting requirements. Multiple bellows are connected to the storage tank of the cooling medium, and a flow control valve and a flow check valve are installed on each bellows.

[0013] In an optional implementation, It also includes the pouring step: Transfer the preheated mold shell into the pouring chamber, turn on the vacuum pump and begin pouring; After pouring is complete, slowly introduce dry air, and after depressurizing to atmospheric pressure, open the furnace door.

[0014] In an optional implementation, The pouring step also includes: Open the flow check valve to allow cooling gas to circulate and cool continuously in the bellows; After cooling, the casting is left at room temperature for a period of time before the module is removed for subsequent processes.

[0015] The investment casting cooling device provided by this invention allows the bellows to be arranged according to the hot spots or key cooling areas of the casting. The flow direction of the cooling medium can be well controlled through the bellows, thereby controlling the area that needs to be cooled. Furthermore, the air outlet on the bellows is away from the gating system, effectively preventing the gating system from being cooled as well. This allows for more effective feeding and alleviates the technical problem in the prior art where the high-speed liquid nitrogen gas flow is difficult to control precisely and inevitably affects the feeding gating system while cooling the casting body. Attached Figure Description

[0016] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0017] Figure 1 This is a schematic diagram of the overall structure of the investment casting cooling device provided in an embodiment of the present invention; Figure 2 This is a schematic diagram of the bellows structure in the investment casting cooling device provided in an embodiment of the present invention; Figure 3 This is a schematic diagram of step one provided in an embodiment of the present invention; Figure 4 A three-dimensional schematic diagram of step one in the cooling method of the investment casting cooling device provided in an embodiment of the present invention; Figure 5 A schematic diagram of step two in the cooling method of the investment casting cooling device provided in an embodiment of the present invention; Figure 6 A schematic diagram of step three in the cooling method of the investment casting cooling device provided in an embodiment of the present invention; Figure 7 A schematic diagram of step six in the cooling method of the investment casting cooling device provided in an embodiment of the present invention; Figure 8 for Figure 7 A magnified structural diagram of point A in the middle.

[0018] Icons: 10-casting; 20-sprue; 30-mold; 100-bellows; 110-vent; 200-storage tank; 300-flow check valve; 400-flow control valve. Detailed Implementation

[0019] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. 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.

[0020] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0021] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0022] The specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are for illustration and explanation only and are not intended to limit the present invention.

[0023] like Figure 1 , Figure 2 As shown, the core of the investment casting cooling device provided by the present invention lies in the precise delivery of the cooling medium to the hot spot area of ​​the casting 10 through the flexible and malleable corrugated pipe 100, so as to achieve controllable and efficient cooling of the local high temperature area.

[0024] The bellows 100 is arranged on the key hot spots on the outer surface of the mold shell 30 according to the actual structure and heat distribution characteristics of the casting 10. It can closely fit the complex irregular surface and ensure that the cooling effect is concentrated in the thick cross-section area that is prone to defects such as shrinkage porosity and shrinkage cavities.

[0025] The bellows 100 is uniformly provided with multiple air outlets 110 along its length. These air outlets 110 are oriented toward the surface of the casting 10 shell and the air outlet direction is clearly away from the gating system 20, so as to avoid the cooling medium directly impacting the gating system 20 and affecting the normal feeding process of the molten metal.

[0026] The cooling medium is sprayed onto the surface of the mold shell 30 through the air outlet 110, forming a local strong convection heat transfer, which significantly improves the heat dissipation rate of the area, thereby controlling the solidification sequence, promoting sequential solidification, and reducing casting stress and deformation risk.

[0027] In practice, the cooling system also includes a storage tank 200 for storing the cooling medium. This storage tank 200 is typically filled with an inert cryogenic gas such as liquid nitrogen or liquid argon to ensure cooling effectiveness while preventing oxidation. One end of the bellows 100 is connected to the storage tank 200 to ensure a continuous supply of the cooling medium.

[0028] Depending on the size, structural complexity, and distribution of hot spots of the casting 10, one or more corrugated pipes 100 can be connected in parallel to the same storage tank 200 to form a multi-channel cooling network, which can meet the simultaneous cooling needs of large areas or multiple independent hot spots.

[0029] To enable start and stop control of the cooling process, a flow check valve 300 is installed at the inlet end of the bellows 100 near the storage tank 200. This valve remains closed until the pouring is completed, and automatically opens after the pouring is completed, thus precisely controlling the start time of cooling and avoiding premature cooling that could interfere with the filling process.

[0030] To further refine the adjustment of cooling intensity, a flow control valve 400 is installed at the end of the bellows 100 furthest from the storage tank 200. This valve dynamically controls the exhaust volume and injection force of each outlet 110 by adjusting the internal pressure and medium flow rate of the bellows 100.

[0031] When it is necessary to accelerate the cooling rate of a specific area, the end flow control valve 400 can be gradually closed, allowing the cooling medium to accumulate pressure inside the pipe, thereby enhancing the kinetic energy and density of the fluid ejected from the small orifice. Conversely, if it is necessary to reduce the cooling intensity, the flow control valve 400 can be opened to release some pressure and reduce the outlet air flow, achieving gradient and adjustable cooling management. This dual-valve collaborative control mechanism gives the entire cooling process good responsiveness and adaptability, making it particularly suitable for products such as large thin-walled aluminum alloy castings 10, which are highly sensitive to temperature field uniformity and solidification path.

[0032] Based on the above, the cooling method of the investment casting cooling device in this embodiment aims to provide a controllable cooling solution for investment casting of large, thin-walled, complex, and irregularly shaped structural parts, laying a technical foundation for the manufacturing of high-end aluminum alloy equipment. Taking the ZL116 aluminum alloy investment casting process as an example, the following explanation is provided: The specific operating procedure is as follows: Step 1: Make wax models according to the requirements and procedures of investment casting, and assemble the wax models into modules, such as... Figure 3 , Figure 4 As shown.

[0033] Step 2: Apply coating to the module according to the normal procedure to complete the shell-making process, such as... Figure 5 As shown.

[0034] Step 3: After shell preparation, dewaxing and firing are performed to form the required mold shell 30, such as... Figure 6 As shown.

[0035] Step 4: Preparation of the bellows 100: Based on the size of the casting 10, cut the bellows 100 for cooling. The diameter of the bellows 100 is selected according to actual needs, such as... Figure 2 As shown; Step 5: Then, make small holes at intervals on the bellows 100, i.e., air outlets 110, such as... Figure 2 As shown; connect the bellows 100 to the cooling medium storage device, and install a cooling medium flow control valve 400 at one end of the bellows 100, as shown. Figure 1 As shown in the diagram, this figure shows three corrugated pipes 100. The number of corrugated pipes 100 used for cooling can be determined according to the requirements of the casting 10.

[0036] The bellows 100 has a cooling medium flow control valve 400 at its end, which can adjust the flow rate of liquid nitrogen. When the casting 10 requires a larger cooling rate, the cooling medium flow control valve 400 can be closed, so that the liquid nitrogen flows out of the small hole in greater intensity. When the casting 10 requires a smaller cooling rate, the cooling medium flow control valve 400 can be opened to reduce the flow of liquid nitrogen out of the small hole, thereby achieving the purpose of controlling the cooling rate.

[0037] Step Six: Then, arrange the bellows 100 on the surface of the casting 10 shell that needs to be cooled, avoiding the gating system 20 of the casting 10, such as... Figure 7 , Figure 8 As shown.

[0038] Before arranging the corrugated pipe 100, the hot junction position must be determined. The corrugated pipe 100 is arranged at the hot junction position, with the air outlet 110 facing the mold shell 30 and away from the runner 20.

[0039] Step 7, Casting: Transfer the preheated mold shell 30 into the casting chamber (the casting chamber is a pressure vessel), turn on the vacuum pump, and start casting after the internal vacuum reaches ≤0.1KPa.

[0040] After casting is completed, dry air is slowly introduced, and the furnace door is opened after the pressure is released to atmospheric pressure. Then, the cooling medium flow check valve 300 is opened to allow inert cooling gas (liquid nitrogen or liquid argon) to be continuously circulated into the bellows 100. After a certain cooling time, the cooling device is turned off. After the casting 10 is cooled at room temperature for a period of time, the mold is removed for subsequent processes such as shell cleaning and cutting.

[0041] The advantages of this cooling method are as follows: Due to the complex characteristics of large structural components, many parts will have areas of uneven thickness. If inert cooling gas is directly blown or the casting 10 is placed in a sealed device and filled with inert cooling gas for circulation cooling, the overall cooling environment of the casting 10 will be uniform, and it will be impossible to effectively control the areas that need to be cooled or the hot spots. However, the bellows 100 can be arranged according to the hot spots or areas that need to be cooled of the casting 10. The inert cooling gas can be well controlled through the bellows 100, thereby controlling the areas that need to be cooled. The use of the bellows 100 also effectively prevents the gating system 20 from being cooled, thus enabling more effective feeding. At the same time, by adjusting the cooling medium flow control valve 400 at the end of the bellows 100, the flow rate of liquid nitrogen can be adjusted. When the casting 10 needs a large cooling rate, the cooling medium flow control valve 400 can be closed, so that the liquid nitrogen flows out of the small hole in greater intensity. When the casting 10 needs a small cooling rate, the cooling medium flow control valve 400 can be opened to reduce the flow of liquid nitrogen out of the small hole, thereby achieving the purpose of controlling the cooling rate.

[0042] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A foundry mould cooling device, characterized in that Comprising: a corrugated pipe (100); the corrugated pipe (100) is arranged at the hot spot area of the casting (10); the corrugated pipe (100) is provided with a plurality of air outlets (110) along the length direction, the air outlet direction of the air outlet (110) is towards the casting (10), and the air outlet direction of the air outlet (110) is away from the sprue (20), and the corrugated pipe (100) is used to deliver cooling medium to the casting (10) through a plurality of air outlets (110).

2. The mold casting cooling device according to claim 1, wherein: the mold casting cooling device further comprises a storage tank (200); the storage tank (200) is used to store the cooling medium, and one end of the corrugated pipe (100) is in communication with the storage tank (200); one or more corrugated pipes (100) are provided, and each of the corrugated pipes (100) is in communication with the storage tank (200).

3. The mold casting cooling device according to claim 2, wherein: the corrugated pipe (100) is provided with a flow check valve (300) at one end close to the storage tank (200), and the flow check valve (300) is used to control the cooling medium in the storage tank (200) to flow into the corrugated pipe (100).

4. The mold casting cooling device according to claim 3, wherein: the corrugated pipe (100) is provided with a flow control valve (400) at one end away from the storage tank (200), and the flow control valve (400) is used to control the flow of the cooling medium in the corrugated pipe (100) to control the flow of the air outlet (110).

5. A cooling method based on the mold casting cooling device according to any one of claims 1 to 4, characterized by, including a cooling step: determine the hot spot position of the casting (10), and arrange the corrugated pipe (100) at the hot spot position, the air outlet (110) of the corrugated pipe (100) is towards the hot spot position, and the air outlet direction of the corrugated pipe (100) is away from the sprue (20).

6. The cooling method according to claim 5, wherein: further comprising a shell making step: make a wax mold, and combine the wax mold into a mold group; coat the mold group with paint to make a shell, and complete the shell making process; after the shell making is completed, perform dewaxing and baking to form the required mold shell (30).

7. The cooling method according to claim 6, wherein: further comprising a corrugated pipe (100) preparation step: according to the size of the casting (10), cut the corrugated pipe (100) for cooling; open holes on the corrugated pipe (100) at certain intervals to form a plurality of air outlets.

8. The cooling method according to claim 7, wherein: further comprising an assembly step: determine the number of corrugated pipes (100) according to the needs of the casting (10), connect a plurality of corrugated pipes (100) with the storage tank (200) of the cooling medium, and install a flow control valve (400) and a flow check valve (300) on each corrugated pipe (100).

9. The cooling method according to claim 8, wherein: further comprising a pouring step: transfer the preheated mold shell (30) into a pouring chamber, and start pouring after opening the vacuum pump; After pouring is completed, dry air is slowly introduced, and the furnace door is opened after pressure is released to atmospheric pressure.

10. The cooling method according to claim 9, wherein, the pouring step further comprises: opening the flow stop valve (300) to introduce cooling gas into the bellows (100) for circulating cooling; after cooling is completed, the cast (10) is left at room temperature for a period of time, and the mold set is removed for subsequent processes.

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