Thin-shell workpiece casting process
By combining high-pressure casting and lost foam casting, the problems of demolding difficulties and deformation in the casting process of thin-shell workpieces have been solved, and efficient and stable casting of thin-shell workpieces has been achieved.
Patent Information
- Application Number
- CN202511700789.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-11-19
- Publication Date
- 2026-02-24
AI Technical Summary
In high-pressure casting or lost foam casting processes, when casting workpieces with thin shell sections and runner sections, it is easy to encounter difficulties in demolding, workpiece deformation, or large milling amounts, which leads to inconvenience in casting.
The thin-shell section is cast using high-pressure casting, and the runner section is cast using lost foam casting. The advantages of the two processes are utilized. The thin-shell section and the runner section are made of the same material and are connected by connecting slots and inserts. The addition of stiffening rods increases stability, and the connection is enhanced by preheating and pressurizing.
This technology enables stable casting of thin-shell workpieces, reduces deformation and demolding difficulties, and improves casting efficiency and molding quality.
Smart Images
Figure CN121551570A_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of casting processes, and in particular to casting processes for thin-shell workpieces. Background Technology
[0002] Casting is a manufacturing process in which molten metal is injected into a mold cavity, where it cools and solidifies into the desired shape. Types of casting include low-pressure casting, high-pressure casting, investment casting, and lost foam casting.
[0003] High-pressure casting refers to the casting process in which molten metal is injected into the cavity of a mold under high pressure, causing the workpiece to solidify rapidly under continuous pressure, and then ejected from the mold after the workpiece is formed. It is characterized by high casting speed and high forming accuracy. Lost foam casting, on the other hand, involves embedding a white film (usually made of foam material) based on the shape of the workpiece in a sand box. Then, under negative pressure, molten metal is injected into the sand box, causing the white film to burn and vaporize, filling the cavity originally occupied by the white film. This allows the molten metal to replace the white film, and after cooling and solidification, it is formed into the desired shape of the workpiece. It can manufacture workpieces with complex shapes that are not easy to demold.
[0004] Some equipment that uses cast parts, such as motors, energy storage bins, and incinerators, requires their outer shells, frames, and / or piping systems to provide a certain degree of heat dissipation to prevent overheating during operation. The outer shells of these devices typically have a thin shell section with a thickness not exceeding 3 mm and a flow channel section with complex cooling channels. This allows the heat dissipation area to be increased through the thin shell section, and the refrigerant flowing within the flow channel section to promptly remove the heat generated during operation.
[0005] Regarding the aforementioned technologies, when casting thin-shell workpieces with thin shell sections and runner sections using high-pressure casting or lost foam casting processes, difficulties in demolding, workpiece deformation, or large milling amounts are prone to occur, making the casting and forming of thin-shell workpieces quite inconvenient. Summary of the Invention
[0006] To facilitate the casting of thin-shell workpieces with flow channels, this application provides a casting process for thin-shell workpieces.
[0007] The casting process for thin-shell workpieces provided in this application adopts the following technical solution: A casting process for thin-shell workpieces includes the following steps: S1. Divide the workpiece into a thin-shell section and a flow channel section; In step S1: the thickness of the thin shell portion is less than 3 mm, the flow channel portion is provided with a cooling channel for the refrigerant to flow, and the material of the thin shell portion is the same as the material of the flow channel portion; S2. The thin-shell portion is cast using a high-pressure casting process; S3. The flow channel section is cast using a lost foam casting process; S4. Connect the thin shell portion and the flow channel portion to each other.
[0008] By adopting the above technical solution, the thin-shell portion with a smaller wall thickness is cast using a high-pressure casting process, making it less prone to deformation during casting. This reduces the likelihood of the thin, flexible white film bending and deforming due to vibration and pressure during lost foam casting, which would cause the subsequently replaced molten metal to bend and deform after forming.
[0009] Furthermore, the runner section with cooling channels is cast using the lost foam casting process, allowing for the rapid formation of complex cooling channels and the timely removal of molding sand used during casting, simplifying demolding. This reduces the difficulties in mold cavity design and workpiece demolding that often occur with high-pressure casting processes, where complex cooling channels and demolding are common.
[0010] Therefore, by casting the thin-shell section and the flow channel section with two different specifications (thin walls and cooling channels) using two casting processes respectively, and then connecting the thin-shell section and the flow channel section with the same material, the advantages of the two casting processes are fully utilized, making it easier to cast thin-shell workpieces with flow channels.
[0011] Optionally, step S3 includes the following steps: S31. The thin-shell portion is placed inside the casting sand box; S32. Connect the white film of the flow channel to the thin shell; S33. Fill the interior of the casting sand box with molding sand for casting; S34. Molten metal for replacing the white film is injected into the interior of the casting sand box.
[0012] By adopting the above technical solution, after the molten metal is injected, the molten metal directly contacts the thin shell part of the same material, which facilitates the direct solidification and connection of the molten metal to the thin shell part after cooling and solidification. This reduces the time for workpiece transfer and interconnection, and helps to improve the casting efficiency of thin shell workpieces with flow channels.
[0013] Optionally, the thin shell portion is provided with a connecting slot, and the white film of the flow channel portion is provided with a connecting post, which is inserted into and adapted to the connecting slot.
[0014] By adopting the above technical solution, on the one hand, when connecting the white film of the flow channel to the thin shell in step S32, inserting the connecting post into the connecting slot will make it less likely for the white film to be squeezed, deformed or detached during filling and compacting of molding sand, thereby reducing the occurrence of deformation of the flow channel during casting in step S3.
[0015] On the other hand, after the connecting pin is replaced by molten metal, it will solidify inside the connecting slot, thereby creating a larger connection area between the flow channel and the thin shell, making it easier to connect the separately cast flow channel and thin shell into a strong whole.
[0016] Optionally, the thin-shell portion is provided with a reinforcing rod, the two ends of which are located inside the thin-shell portion and the connecting post, respectively, and the material of the reinforcing rod is the same as that of the workpiece.
[0017] By adopting the above technical solution, on the one hand, the reinforcing rod can increase the strength of the white film, making it less prone to deformation during the casting process; on the other hand, the solidified reinforcing rod can connect the thin shell part and the flow channel part after the workpiece is formed, making the connection between the thin shell part and the flow channel part more stable.
[0018] Optionally, the cooling channel of the flow channel is provided with a U-shaped bend, and one end of the stiffening rod is surrounded by the U-shaped bend.
[0019] By adopting the above technical solution, on the one hand, the extension into the U-shaped bend section can increase the connection stability between the stiffening rod and the flow channel. On the other hand, the stiffening rod is conducive to increasing the strength of the white film in the U-shaped bend section, making it less likely for the molding sand filling the cooling channel to push the U-shaped bend section, thus reducing the occurrence of complete deformation of the U-shaped bend section with more cavities.
[0020] Optionally, in step S34: the position of the thin-shell portion that will contact the molten metal is preheated before the molten metal is injected; Furthermore, S3 also includes the following steps: S35. The connection between the thin shell portion and the flow channel portion is heated. In step S35: When connecting the heating, the temperature of the thin shell part is first raised to the melting temperature, then the temperature of the connection between the thin shell part and the flow channel part is lowered to the holding temperature, and then the connection between the thin shell part and the flow channel part is held at the holding temperature.
[0021] By adopting the above technical solution, on the one hand, the temperature difference between the thin shell and the molten metal is reduced, thus reducing the occurrence of cracking in the thin shell. On the other hand, it facilitates the diffusion of metal atoms, making the bonding surface between the thin shell and the flow channel more stable.
[0022] Optionally, in step S4: after the cooling process in step S35 begins, the thin-shell portion and the flow channel portion are pressed together by applying pressure.
[0023] By adopting the above technical solution, it is beneficial to make the joint surface between the thin shell part and the flow channel part more stable.
[0024] Optionally, in step S34: preheating is performed by inductive heating; In step S35, the connection heating is performed by inductive heating.
[0025] By adopting the above technical solution, inductive heating has high efficiency and can quickly heat the thin shell part and the flow channel part.
[0026] Optionally, in step S33: After filling the casting sand box with molding sand for casting, the molding sand in the casting sand box is vibrated to compact it; In step S31: the thin shell part is located at the bottom of the flow channel part, and the bottom of the casting sand box is equipped with several positioning rods by locking bolts. When the thin shell part is located inside the casting sand box, the several positioning rods are arranged around the thin shell part.
[0027] By adopting the above technical solution, when the molding sand is vibrated, the thin shell part of the metal material at the bottom, which is relatively heavy, will be less likely to deviate due to inertia under the limiting action of the positioning rod. This reduces the displacement difference between the white film in the flow channel at the top and the thin shell part at the bottom, which helps to reduce the occurrence of white film breakage or workpiece deformation.
[0028] In addition, for thin-shell parts of different specifications, the positioning plate can be rotated and locked by turning the locking bolts, thereby fixing the thin-shell parts of different specifications.
[0029] Optionally, the thin shell portion may be derusted before connecting the thin shell portion and the flow channel portion to each other.
[0030] By adopting the above technical solution, it is beneficial to reduce the oxide inclusions that appear at the interface between the thin shell part and the flow channel part.
[0031] In summary, this application includes at least one of the following beneficial technical effects: 1. The thin-walled shell section with a small wall thickness is cast using high-pressure casting, which makes the thin-walled shell section less prone to deformation during the casting process. This reduces the likelihood of the thin, flexible white film bending and deforming due to vibration and extrusion during lost foam casting, which would cause the subsequently replaced molten metal to bend and deform after forming. Furthermore, the flow channel section with cooling channels is cast using the lost foam casting process, allowing for the rapid formation of complex cooling channels and the timely removal of molding sand used during casting, simplifying demolding. This reduces the difficulties in mold cavity design and workpiece demolding that often occur with high-pressure casting processes involving complex cooling channels. Therefore, by casting the thin-shell section and the runner section with two different specifications (thin-walled and cooling channels) using two different casting processes, and then connecting the thin-shell section and the runner section with the same material, the advantages of the two casting processes are fully utilized, making it easier to cast thin-shell workpieces with runners. 2. After the molten metal is injected, the molten metal directly contacts the thin shell part of the same material, which makes it easy for the molten metal to solidify and connect directly to the thin shell part after cooling and solidification. This reduces the time for workpiece transfer and interconnection, and helps to improve the casting efficiency of thin shell workpieces with flow channels. 3. On the one hand, when connecting the white film of the flow channel to the thin shell in step S32, inserting the connecting post into the connecting slot will make it less likely for the white film to be squeezed, deformed or detached during filling and compacting of molding sand, thereby reducing the occurrence of flow channel deformation during casting in step S3. On the other hand, after the connecting pin is replaced by molten metal, it will solidify inside the connecting slot, thereby creating a larger connection area between the flow channel and the thin shell, making it easier to connect the separately cast flow channel and thin shell into a strong whole. 4. When the molding sand is vibrated, the thin shell part of the metal material at the bottom, which is relatively heavy, will be less likely to deviate due to inertia under the limiting action of the positioning rod. This reduces the displacement difference between the white film in the flow channel at the top and the thin shell part at the bottom, which helps to reduce the occurrence of white film breakage or workpiece deformation. In addition, for thin-shell parts of different specifications, the positioning plate can be rotated and locked by turning the locking bolts, thereby fixing the thin-shell parts of different specifications. Attached Figure Description
[0032] Figure 1 This is a schematic diagram showing the connection between the thin shell portion and the white film of the flow channel portion in Embodiment 1 of this application.
[0033] Figure 2 This is an overall schematic diagram of the thin-shell portion of Embodiment 1 of this application.
[0034] Figure 3 This is a schematic diagram of the overall white film in the flow channel section of Embodiment 1 of this application.
[0035] Figure 4 This is an exploded schematic diagram of the white film in the flow channel section of Embodiment 1 of this application.
[0036] Figure 5 This is an overall schematic diagram of the foam sub-block of the white film in the flow channel section of Embodiment 1 of this application.
[0037] Figure 6 This is an overall schematic diagram of the casting sand box in Embodiment 2 of this application.
[0038] Figure 7This is a schematic diagram of the distribution of the positioning rods in Embodiment 2 of this application.
[0039] Explanation of reference numerals in the attached drawings: 1. Thin-shell section; 101. Connecting slot; 2. Flow channel section; 21. Cooling channel; 211. U-shaped bend section; 22. Connecting post; 23. Reinforcing rod; 3. Sand box body; 31. Positioning rod; 32. Locking bolt; 4. Heating coil. Detailed Implementation
[0040] The following is in conjunction with the appendix Figure 1-7 This application will be described in further detail.
[0041] Example 1: This application discloses a casting process for thin-shell workpieces. (Refer to...) Figure 1 The casting process for thin-shell workpieces includes: S1. Divide the workpiece into a thin-shell section 1 and a flow channel section 2; S2. The thin-shell part 1 is cast using a high-pressure casting process; S3. Cast the runner section 2 using the lost foam casting process; S4. Connect the thin shell part 1 and the flow channel part 2 to each other.
[0042] In step S1: Reference Figure 1 and Figure 2 During casting in step S3, the thin-shell portion 1 is located at the bottom of the flow channel portion 2. The thickness of the thin-shell portion 1 is less than 3 mm, and the flow channel portion 2 is provided with a cooling channel 21 for the flow of refrigerant. The material of the thin-shell portion 1 is the same as the material of the flow channel portion 2, so that the thin-shell portion 1 and the flow channel portion 2 can be more easily and tightly connected during casting. In the embodiment of this application, the materials of the thin-shell portion 1 and the flow channel portion 2 are iron or steel to facilitate heating and casting.
[0043] In step S2: High-pressure casting refers to a casting process in which molten metal is injected into the cavity of a mold at a high pressure with an injection ratio greater than 30 MPa, causing the workpiece to solidify rapidly under continuous pressure, and then ejecting the workpiece from the mold after it is formed.
[0044] Step S2 includes the following steps: S21. Spray release agent into the cavity of the mold, and then close the mold to seal the cavity; The shape of the cavity closure seal corresponds to the overall shape of the thin shell part 1, so that the molten metal can be accurately solidified and formed in the cavity.
[0045] S22. Expel the gas from the cavity and inject molten metal into the cavity; S23. Maintain pressure on the molten metal in the cavity; S24. Cool the mold. S25. Open the mold and remove the cooled and solidified thin shell part 1 from the cavity.
[0046] In step S3: Lost foam casting is a one-time casting process in which a white foam material that can be vaporized replaces the traditional wooden or metal mold. During casting, the white foam is embedded in the molding sand of the casting sand box. Molten metal is poured in to vaporize and escape the mold. The molten metal occupies the cavity of the original white foam and replaces the white foam. After cooling and solidification, a workpiece corresponding to the shape of the white foam is formed.
[0047] Step S3 includes the following steps: S31. Remove rust from the thin shell part 1, and then place the thin shell part 1 inside the casting sand box.
[0048] The thin shell part 1 needs to be fixed to the bottom of the casting sand box so that the thin shell part 1 is not easy to shake during the casting process, especially before the molding sand is fully compacted, so as to ensure the forming accuracy of the workpiece.
[0049] S32. Apply fire-retardant coating to the surface of the white film in the flow channel section 2, and after drying with the fire-retardant coating, connect the white film to the thin shell section 1.
[0050] Reference Figure 2 and Figure 3 The top of the thin shell portion 1 is provided with several connecting slots 101, and the openings of the connecting slots 101 are all vertically upward. The bottom of the white film of the flow channel portion 2 is integrally provided with several connecting pins 22, and the connecting pins 22 are respectively inserted into and adapted to each connecting slot 101, so that the white film of the flow channel portion 2 is connected to the thin shell portion 1 by inserting each connecting pin 22 into each connecting slot 101.
[0051] By inserting the white film into the thin shell portion 1, on the one hand, the white film is less likely to be squeezed, deformed, or detached during filling and compacting of the molding sand, thereby reducing the occurrence of deformation in the flow channel portion 2. On the other hand, after the connecting insert 22 is replaced by molten metal, it will solidify inside the connecting slot 101, thereby providing a larger connection area between the flow channel portion 2 and the thin shell portion 1, making it easier to connect the separately cast flow channel portion 2 and thin shell portion 1 into a strong whole.
[0052] Reference Figure 4 In this embodiment, the white film of the flow channel 2 is formed by bonding several foam sub-blocks together with adhesive. Figure 5 The white film of the flow channel 2 can be divided into an inner white film and an outer white film. The inner white film and the outer white film are each provided with half of the cooling channel 21. When the inner white film and the outer white film are bonded together as a whole, the two halves of the cooling channel 21 are completely joined together.
[0053] Reference Figure 4 and Figure 5 The cooling channel 21 is provided with several U-shaped bends to ensure that the refrigerant flowing through the cooling channel 21 has sufficient heat absorption area and heat absorption time. Several reinforcing rods 23 are fixedly embedded in the thin-shell section 1, and each reinforcing rod 23 is correspondingly arranged with a connecting post 22. One end of each reinforcing rod 23 is located inside the thin-shell section 1 and surrounded by the U-shaped bends, while the other end of each reinforcing rod 23 is located inside the connecting post 22. This allows the reinforcing rod 23 and the connecting post 22 to be interconnected through the reinforcing rod 23, reducing the possibility of breakage of the slender connecting post 22 during assembly and handling. Furthermore, the material of the reinforcing rod 23 is the same as the material of the workpiece to ensure a stable connection between the reinforcing rod 23 and the thin-shell section 1 and the flow channel section 2.
[0054] The reinforcing rods 23 serve two purposes: firstly, to prevent the white film, especially the slender connecting pins 22, from bending and deforming during the casting process; and secondly, by fixing the reinforcing rods 23 at both ends to the thin-shell section 1 and the flow channel section 2, the thin-shell section 1 and the flow channel section 2 are effectively reinforced and connected after the workpiece is formed, making the connection between the thin-shell section 1 and the flow channel section 2 more stable. Furthermore, this also reduces the possibility of deformation of the U-shaped bending section due to the presence of numerous cavities nearby, thereby reducing the likelihood of blockage and difficult repair of the cooling channels 21 inside the flow channel section 2.
[0055] S33. Fill the casting sand box with molding sand for casting, and then vibrate to compact the molding sand in the casting sand box.
[0056] The molding sand can be made of quartz sand or granulated sand.
[0057] S34. Apply negative pressure to the inside of the casting sand box and maintain it. Preheat the part of the thin shell 1 that will be in contact with the molten metal, and then inject molten metal into the inside of the casting sand box to replace the white film.
[0058] The preheating method can be a known workpiece heating method in the art, such as thermal radiation heating, combustion heating, or induction heating, to reduce the occurrence of cracking in the thin shell part 1 with a small thickness, and to make metal atoms diffuse more easily, so that the thin shell part 1 is more firmly connected to the flow channel part 2.
[0059] S35. The connection between the thin shell part 1 and the flow channel part 2 is heated.
[0060] The connection heating method can be any workpiece heating method known in the art, such as thermal radiation heating, combustion heating, or induction heating. During connection heating, the temperature of the thin shell part 1 is first raised to the melting temperature, then the temperature of the connection between the thin shell part 1 and the flow channel part 2 is lowered to the holding temperature, and then the connection between the thin shell part 1 and the flow channel part 2 is held at the holding temperature to reduce the adverse effects of residual thermal stress.
[0061] In this embodiment, the preheating described in step S34 and the connection heating described in step S35 are both performed by inductive heating to improve energy utilization and heating efficiency.
[0062] In step S4: After the cooling in step S35 begins, the thin shell part 1 and the flow channel part 2 are pressed together by applying pressure, so that the joint surface between the thin shell part 1 and the flow channel part 2 is more stable.
[0063] The implementation principle of the thin-shell workpiece casting process in Embodiment 1 of this application is as follows: two casting processes are used to cast thin-shell part 1 and runner part 2 with two different specifications and characteristics. Then, the thin-shell part 1 and runner part 2 are connected to each other in the casting sand box. This fully utilizes the advantages of the two casting processes, reduces the time for workpiece transfer and connection, not only improves the casting efficiency of thin-shell workpieces with runners, but also makes it easier to cast thin-shell workpieces with runners.
[0064] Example 2: This application discloses a casting sand box for use in the thin-shell workpiece casting process described in Example 1.
[0065] Reference Figure 6 The casting sand box includes a sand box body 3 and a heating coil 4. The sand box body 3 provides a working surface for steps S3 and S4. The material of the sand box body 3 is not easily heated by inductance, such as stone or ceramic. The heating coil 4 surrounds the sand box body 3 to heat the thin-shell portion 1, the flow channel portion 2, and the reinforcing rod 23 inside the sand box body 3. The heating coil 4 can be vertically raised and lowered by a lifting module (not shown in the figure) to heat or keep the workpiece at different heights.
[0066] Reference Figure 7 Four positioning rods 31 are installed at the bottom of the sand box body 3 by locking bolts. When the thin shell part 1 is located inside the casting sand box, several positioning rods 31 are arranged around the thin shell part 1. The positioning rods 31 are arranged in an "L" shape, and the lengths of the two ends of the positioning rods 31 are not the same, so as to clamp and fix the thin shell parts 1 of different specifications by rotating the positioning rods 31.
[0067] The above are all preferred embodiments of this application, and are not intended to limit the scope of protection of this application. Therefore, all equivalent changes made in accordance with the structure, shape and principle of this application should be covered within the scope of protection of this application.
Claims
1. A casting process for thin-shell workpieces, characterized in that: Includes the following steps: S1. Divide the workpiece into a thin-shell section 1 and a flow channel section 2; In step S1: the thickness of the thin shell part 1 is less than 3 mm, the flow channel part 2 is provided with a cooling channel 21 for the flow of refrigerant, and the material of the thin shell part 1 is the same as the material of the flow channel part 2; S2. The thin-shell part 1 is cast using a high-pressure casting process; S3. Cast the flow channel section 2 using a lost foam casting process; S4. Connect the thin shell part 1 and the flow channel part 2 to each other.
2. The thin-shell workpiece casting process according to claim 1, characterized in that: Step S3 includes the following steps: S31. The thin shell part (1) is placed inside the casting sand box; S32. Connect the white film of the flow channel (2) to the thin shell (1); S33. Fill the interior of the casting sand box with molding sand for casting; S34. Molten metal for replacing the white film is injected into the interior of the casting sand box.
3. The thin-shell workpiece casting process according to claim 2, characterized in that: The thin shell part (1) is provided with a connecting slot (101), and the white film of the flow channel part (2) is provided with a connecting post (22), which is inserted into and adapted to the connecting slot (101).
4. The thin-shell workpiece casting process according to claim 3, characterized in that: The thin shell part (1) is provided with a reinforcing rod (23), the two ends of which are located inside the thin shell part (1) and the connecting post (22), respectively, and the material of the reinforcing rod (23) is the same as that of the workpiece.
5. The thin-shell workpiece casting process according to claim 4, characterized in that: The cooling channel (21) of the flow channel (2) is provided with a U-shaped bend, and one end of the reinforcing rod (23) is surrounded by the U-shaped bend.
6. The thin-shell workpiece casting process according to claim 2, characterized in that: In step S34: before injecting molten metal, the thin shell portion (1) is preheated at the position where it will contact the molten metal; Furthermore, S3 also includes the following steps: S35. The connection between the thin shell part (1) and the flow channel part (2) is heated. In step S35: When connecting the heating, the temperature of the thin shell part (1) is first raised to the melting temperature, then the temperature of the connection between the thin shell part (1) and the flow channel part (2) is lowered to the heat preservation temperature, and then the connection between the thin shell part (1) and the flow channel part (2) is kept at the heat preservation temperature.
7. The thin-shell workpiece casting process according to claim 6, characterized in that: In step S4: after the cooling process in step S35 begins, the thin shell part (1) and the flow channel part (2) are pressed together by applying pressure.
8. The thin-shell workpiece casting process according to claim 6, characterized in that: In step S34: preheating is performed by inductive heating; In step S35, the connection heating is performed by inductive heating.
9. The thin-shell workpiece casting process according to claim 2, characterized in that: In step S33: After filling the casting sand box with molding sand for casting, the molding sand in the casting sand box is vibrated to compact it; In step S31: the thin shell part (1) is located at the bottom of the flow channel part (2), and a number of positioning rods (31) are installed at the bottom of the casting sand box by locking bolts. When the thin shell part (1) is located inside the casting sand box, the number of positioning rods (31) are arranged around the thin shell part (1).
10. The thin-shell workpiece casting process according to claim 1, characterized in that: Before connecting the thin shell part (1) and the flow channel part (2) to each other, the thin shell part (1) is derusted.