Casting, vehicle, and casting manufacturing method

Abstract

The invention provides a casting, a vehicle and a manufacturing method of the casting. A main body of the casting is formed by a thin wall, at least one hollow cavity is defined by the thin wall, the cavity has an extending direction, and at least one part of the section of the cavity in the extending direction is of a closed structure. The casting, the vehicle and the manufacturing method of the casting are simple in structure and high in integration degree.

Description

Technical Field

[0001] The present application relates to the field of vehicle technology, and in particular to a casting, a vehicle and a method for manufacturing the casting. Background Art

[0002] In order to improve the strength and rigidity of vehicle products, a closed cavity structure is usually designed in the body structure. The existing technology often connects multiple parts to form a closed cavity, which will lead to an increasing number of parts in the body structure, a more complex overall structure, and a low degree of integration between parts, which increases the complexity and production cost of the vehicle.

[0003] Therefore, it is necessary to provide an improved casting, vehicle and method for manufacturing the casting to solve the above problems. Summary of the invention

[0004] The present application provides a casting with a simple structure and high integration, a vehicle and a method for manufacturing the casting.

[0005] The present application discloses a casting, the main body of which is formed by thin walls, wherein the thin walls surround at least one hollow cavity, the cavity has an extension direction, and at least a part of the cross section of the cavity in the extension direction is a closed structure.

[0006] Furthermore, the casting is made by a vacuum centrifugal casting process, and a vacuum adsorption technology is used during the centrifugal casting.

[0007] Furthermore, the thin wall includes an outer wall, the outer wall encloses the cavity, the outer wall includes a plurality of cavity surfaces, and the plurality of cavity surfaces may be at least two planes, curved surfaces, or a combination of a plane and a curved surface.

[0008] Furthermore, the thin wall also includes a partition wall, which is located in the cavity and has two ends connected to the outer wall, and the partition wall divides the cavity into a plurality of closed sub-cavities.

[0009] Furthermore, the thin wall also includes a connecting wall, and the connecting wall is located outside the cavity and connected to the outer wall.

[0010] Furthermore, the cavity includes a first cavity and a second cavity that are separately arranged, and two ends of the connecting wall are respectively connected to an outer wall of the first cavity and an outer wall of the second cavity.

[0011] Furthermore, the connecting wall is a plane, a curved surface, or a combination of a plane and a curved surface, and the connecting wall can form a semi-enclosed cavity.

[0012] Furthermore, the cavity further includes a third cavity and a fourth cavity that are arranged to intersect each other; the third cavity and the fourth cavity share the outer wall at the intersection.

[0013] Furthermore, the thin wall also includes a first reinforcing rib located in the cavity, the first reinforcing rib has the same extension direction as the cavity and a length less than the extension length of the cavity; one side of the first reinforcing rib is connected to the outer wall, and the other opposite side is disconnected from the outer wall.

[0014] Furthermore, the thin wall also includes a second reinforcing rib located in the cavity, and the second reinforcing rib is arranged perpendicularly or obliquely to the first reinforcing rib; one side of the second reinforcing rib is connected to the outer wall, and the other opposite side is disconnected from the outer wall.

[0015] Furthermore, the thin wall further includes an end wall, and the end wall is arranged at least at one end of the extension direction of the cavity, and the end wall partially or completely closes the end surface of the cavity.

[0016] Furthermore, a local thickening structure is formed on the thin wall; and a penetrating forming hole is opened on the local thickening structure.

[0017] Furthermore, the thickness of the thin wall is variable; the minimum thickness of the thin wall is 0.8 mm; and / or the maximum thickness of the thin wall is 2.5 mm.

[0018] Furthermore, the casting is made of steel.

[0019] The present application also discloses a vehicle, comprising the casting as described above.

[0020] The present application also discloses a method for manufacturing a casting, wherein the casting is formed by thin walls, the thin walls enclosing at least one hollow cavity, the cavity having an extension direction, and at least a portion of the cross-section of the cavity in the extension direction is a closed structure; the manufacturing method adopts a vacuum centrifugal casting process, and vacuum adsorption technology is used during centrifugal casting; the casting method uses a sand core as a mold.

[0021] Furthermore, the sand core includes at least one inner core and at least two outer cores, the outer surface of the inner core is the same as the inner contour of the cavity, and a pouring gate is formed between two adjacent outer cores.

[0022] The casting, vehicle and casting manufacturing method of the present application effectively reduce the weight of the casting by setting the main body of the casting as a thin wall, which is conducive to realizing the lightweight design of the product. At the same time, the thin wall surrounds a hollow cavity, and at least a part of the cross section of the cavity in the extension direction is a closed structure, so that a closed cavity is formed in the casting, which improves the rigidity and strength of the casting. In addition, since the casting of the present application is formed by casting in one piece, this manufacturing method simplifies the production process and improves production efficiency.

[0023] It is to be understood that the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the present specification. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the specification and, together with the description, serve to explain the principles of the specification.

[0025] Figure 1 It is a cross-sectional view of the cavity of the casting of the present application.

[0026] Figure 2 It is a cross-sectional view of another cavity of the casting of the present application.

[0027] Figure 3 It is a cross-sectional view of another cavity of the casting of the present application.

[0028] Figure 4 It is a cross-sectional view of another cavity of the casting of the present application.

[0029] Figure 5 It is a stereoscopic view when the casting of this application is a front cabin assembly.

[0030] Figure 6 It is a three-dimensional view when the casting of the present application is a front floor assembly.

[0031] Figure 7 It is a cross-sectional view of an embodiment of the casting of the present application.

[0032] Figure 8 It is a three-dimensional diagram of an embodiment of the casting of the present application.

[0033] Fig. 9 It is a cross-sectional view of an embodiment of the casting of the present application.

[0034] Fig.10 yes Figure 1 Schematic diagram of the sand core assembly of the casting.

[0035] Description of Figure Numbers: 10. Thin wall; 11. Outer wall; 111. Outer wall; 112. Outer wall; 101. Cavity surface; 102. Cavity surface; 12. Partition wall; 13. Connecting wall; 14. End wall; 15. First reinforcing rib; 16. Second reinforcing rib; 20. Cavity; 201. Sub-cavity; 202. First sub-cavity; 203. Second sub-cavity; 204. Third sub-cavity; 205. Concave cavity; 21. First cavity; 22. Second cavity; 23. Third cavity; 231. Top wall; 24. Fourth cavity; 30. Local thickening structure; 31. Forming hole; 40. Sand core; 41. Inner core; 42. Outer core; 43. Casting gate; 51. Front longitudinal beam; 511. First cavity; 512. Second cavity; 52. Shock absorber seat; 53. Front lower plate; 54. Torque box. DETAILED DESCRIPTION

[0036] Here, the technical solutions in the embodiments (or "implementation methods") of the present application will be described clearly and completely in conjunction with the accompanying drawings. When the following description refers to the drawings, unless otherwise indicated, the same numbers in different drawings represent the same or similar elements.

[0037] It should be noted that the terms "first", "second", etc. in the specification and claims of the present application and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchangeable where appropriate, so that the embodiments of the present application described herein can be implemented in an order other than those illustrated or described herein. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the present application. On the contrary, they are merely examples of devices and methods consistent with some aspects of the present application as detailed in the attached claims.

[0038] Next, the embodiments of this specification are described in detail.

[0039] like Figure 1 As shown, the present application provides a casting, the main body of which is formed by a thin wall 10. The thin wall 10 surrounds at least one hollow cavity 20, the cavity 20 has an extension direction, and at least a part of the cross section of the cavity 20 in the extension direction is a closed structure.

[0040] It is understandable that the extension direction of the cavity 20 is the general direction of the cavity 20. The shape of the cavity 20 can be flexibly set, and the extension direction of the cavity 20 can also be flexibly defined. For example, when the thin wall 10 is surrounded by a tubular structure, the cavity 20 formed is approximately cylindrical or rectangular, and the extension direction of the cavity 20 is the length direction of the cylinder or rectangular. When the thin wall 10 is surrounded by a spherical structure, the cavity 20 formed is approximately spherical, and there are multiple extension directions of the cavity 20 formed, and the extension direction of the cavity 20 is the diameter direction of the sphere. When the thin wall 10 is bent, the extension direction of the cavity 20 enclosed therein may also change.

[0041] The casting of the present application is made by vacuum centrifugal pouring process, and vacuum adsorption technology is used during centrifugal pouring. Vacuum adsorption technology can make the raw materials of the casting more fluid and have stronger filling capacity during the pouring process, and can fill the mold well even in a narrow cavity to form a thin wall 10. Centrifugal pouring helps to drive the raw materials of the casting to fill quickly and evenly. Due to the effect of centrifugal force, the casting is usually more compact, and the probability of pores and other defects will be greatly reduced. For castings with a cavity 20 and a thin wall 10, the vacuum centrifugal pouring process can ensure rapid filling, improve the quality of the casting and improve production efficiency.

[0042] The casting of the present application uses sand cores as molds, and can cast a variety of castings with complex structures and complex cavities, and can achieve higher precision and details. The internal chambers of several sand cores and the gaps between different sand cores together form a cavity, and the shape of the cavity is consistent with the shape of the casting.

[0043] Please also refer to Figure 2 The thin wall 10 includes an outer wall 11, and the outer wall 11 surrounds a cavity 20. The outer wall 11 includes a plurality of cavity surfaces, and the plurality of cavity surfaces can be at least two planes, curved surfaces, or a combination of a plane and a curved surface. Figure 2 The outer wall 11 includes a cavity surface 101 and a cavity surface 102 , and the cavity surface 101 and the cavity surface 102 are both curved surfaces bent in the middle.

[0044] It is worth noting that, although the outer wall 11 is divided into different cavity surfaces in this embodiment, in fact, all cavity surfaces are integrally cast. The cavity surface can be defined according to different situations, for example, Figure 1 The outer wall 11 of the middle cavity 20 can be considered as being formed by connecting four planar cavity surfaces, or as being formed by connecting two curved cavity surfaces, or as a combination of two planar cavity surfaces and one curved cavity surface, and so on. Figure 2 The curved cavity surface 101 in FIG. 1 can also be regarded as formed by connecting two planar cavity surfaces.

[0045] The cavity 20 of the present application may be of variable cross-section. Compared with products manufactured by rolling or extrusion molding, the casting of the present application is not subject to the requirement of uniform cross-section, and the cavity 20 may be designed more flexibly and complexly.

[0046] like Figure 3 and Figure 4 As shown, in some embodiments, the thin wall 10 further includes a partition wall 12. The partition wall 12 is located in the cavity 20, and both ends of the partition wall 12 are connected to the outer wall 11. The partition wall 12 divides the cavity 20 into a plurality of closed sub-cavities 201. The casting of the present application can be integrally formed to form a multi-cavity structure, and the adjacent sub-cavities 201 share the thin wall 10, so that the overall weight is reduced and the production efficiency is improved.

[0047] Figure 3 In the embodiment shown, one end of the cavity 20 is enlarged compared to the other end. By providing two partition walls 12, the cavity 20 at the enlarged end is separated into a sub-cavity 201, so that the outer wall 11 there is not easily deformed or unstable, thereby improving the overall strength and impact resistance of the casting.

[0048] Figure 4 In the illustrated embodiment, the outer wall 11 is closed to form a cavity 20. Both ends of the partition wall 12 are connected to the outer wall 11, and the cavity 20 is divided into a first sub-cavity 202, a second sub-cavity 203, and a third sub-cavity 204. The provision of the partition wall 12 forms a double-layer cavity in the casting, wherein the first sub-cavity 202 and the second sub-cavity 203 are located in the upper layer, and the third sub-cavity 204 is located in the lower layer.

[0049] like Figure 5 and Figure 6 As shown, the thin wall 10 further includes a connecting wall 13, which is located outside the cavity 20 and one side of the connecting wall 13 is connected to the outer wall 11. The connecting wall 13 can connect different cavities 20, and can also be designed in different shapes to play a shaping role and facilitate cooperation with other components.

[0050] like Figure 5 and Figure 6 As shown, in some cases, the connecting wall 13 is a plane, a curved surface, or a combination of a plane and a curved surface, and the connecting wall 13 can form a semi-enclosed cavity 205. In some cases, the cavity 20 includes a first cavity 21 and a second cavity 22 that are separately arranged. The two ends of the connecting wall 13 are respectively connected to the outer wall 111 of the first cavity 21 and the outer wall 112 of the second cavity 22.

[0051] Figure 5 The casting shown is the front engine compartment assembly of the vehicle. The front engine compartment assembly includes a front longitudinal beam 51, a shock absorber seat 52, a front wall lower plate 53 and a torque box 54. Please also refer to Figure 3, a first chamber 511 can be formed inside the front longitudinal beam 51, and the front lower plate 53 and the torsion box 54 can be enclosed to form a second chamber 512. The first chamber 511 and the second chamber 512 are connected along the front-to-back direction of the vehicle body, and the second chamber 512 is enlarged relative to the first chamber 511. The shock absorber seat 52 is connected to the front longitudinal beam 51. It can be understood that the shock absorber seat 52 can be regarded as a connecting wall 13. The connecting wall 13 is connected to the front longitudinal beam 51 and is cast in the shape of the shock absorber seat 52. The connecting wall 13 is bent to form a concave cavity 205 with an opening facing downward, which is used to assemble the shock absorber during the vehicle assembly process.

[0052] Figure 6 The casting shown is a front floor assembly of a vehicle. The front floor assembly includes a front floor, a pair of sill beams located on both sides of the front floor, and a central channel and a seat cross beam arranged on the front floor. The first cavity 21 and the second cavity 22 are the inner cavities of the sill beams on both sides. The front floor can be regarded as a connecting wall 13, connecting the outer wall 111 and the outer wall 112.

[0053] Furthermore, in some cases, the cavity 20 further includes a third cavity 23 and a fourth cavity 24 that are arranged to intersect each other, and the third cavity 23 and the fourth cavity 24 share the outer wall 11 at the intersection. Figure 6 As shown, in the front floor assembly, the central channel and the front floor are combined to form a third cavity 23, and the seat cross beam and the front floor are combined to form a fourth cavity 24. The third cavity 23 and the fourth cavity 24 in the front floor assembly are arranged to intersect, and the two share the outer wall 11 at the intersection (that is, the top wall 231 and the bottom wall at the intersection of the two).

[0054] In this way, when the product needs to be designed with two beams intersecting, the casting of the present application can be cast as one piece through a vacuum centrifugal casting process, which can avoid the tedious process of manufacturing them separately and then splicing them, improve production efficiency, and make the structure of the connection smoother and more fluent.

[0055] The thin wall 10 also includes reinforcing ribs to enhance the structural strength. The shape, length and direction of the reinforcing ribs are not limited. The reinforcing ribs can be arranged inside the cavity, outside the cavity, or extend on both the inside and outside of the cavity. By arranging the reinforcing ribs, the bending, compressive and tensile strengths of the casting can be effectively increased. Increasing the local rigidity and distributed stress can make the casting more stable during use, avoid deformation or cracking, and improve the rigidity and stability of the casting.

[0056] Please also refer to Figure 1 , Figure 4 and Figure 7The reinforcing ribs include a first reinforcing rib 15 located in the cavity 20. One side of the first reinforcing rib 15 is connected to the outer wall 11, and the other side opposite to the first reinforcing rib 15 is disconnected from the outer wall 11. The first reinforcing rib 15 extends in the same direction as the cavity 20 and has a length less than the extension length of the cavity 20. In the same cavity 20, the number of first reinforcing ribs 15 can be set to be multiple. The multiple first reinforcing ribs 15 can be distributed in a breakpoint manner, which reduces the weight of the casting, saves materials, and reduces costs without affecting the reinforcement effect.

[0057] like Figure 7 As shown, the reinforcing ribs also include a second reinforcing rib 16 located in the cavity 20. One side of the second reinforcing rib 16 is connected to the outer wall 11, and the other side opposite to the outer wall 11 is disconnected. The second reinforcing rib 16 is arranged perpendicularly or obliquely to the first reinforcing rib 15 to achieve a better reinforcing effect, so that the strength and rigidity of the casting are further improved.

[0058] like Figure 8 As shown, the thin wall 10 further includes an end wall 14. The end wall 14 is disposed at at least one end of the extension direction of the cavity 20, and partially or completely closes the end surface of the cavity 20 to improve the sealing performance of the cavity 20. In some cases, when the cavity 20 is divided into a plurality of sub-cavities 201, the end wall 14 may also selectively close the end surfaces of some of the sub-cavities 201 to accommodate different designs.

[0059] like Fig. 9 As shown, a local thickening structure 30 is formed on the thin wall 10, and a through-molding hole 31 is opened on the local thickening structure 30. The arrangement of the local thickening structure 30 and the molding hole 31 provides space for the assembly of the casting and other parts, without the need to add other standard parts.

[0060] It is understandable that, although the above description names the various parts of the casting differently according to their positional relationship or function, they are essentially a component of the casting, which is integrally formed by vacuum centrifugal casting during the casting process. The casting of the present application can integrally form a thin wall 10 of complex shape, and the thin wall forms a closed cavity 20.

[0061] The thickness of the thin wall 10 is variable. The minimum thickness of the thin wall 10 is 0.8 mm, and the maximum thickness of the thin wall 10 is 2.5 mm, which effectively reduces the weight of the entire casting and is conducive to meeting the requirements of lightweight design of products. The casting is made of steel and has low cost.

[0062] The present application also provides a vehicle, comprising the casting as described above. The casting may be a relatively large and complex structure such as a front cabin assembly, a front floor assembly, a rear floor assembly, or a simple structure such as a tube beam.

[0063] The present application also provides a method for manufacturing a casting. The casting is formed by a thin wall 10, and the thin wall 10 surrounds at least one hollow cavity 20. The cavity 20 has an extension direction, and at least a part of the cross section of the cavity 20 in the extension direction is a closed structure.

[0064] The method for manufacturing castings uses sand cores as molds. A plurality of sand cores form the mold, and the internal chambers of the plurality of sand cores and the gaps between different sand cores together form a mold cavity, and the shape of the mold cavity is consistent with the shape of the casting to be produced.

[0065] The design of multiple sand cores forming the cavity enables the mold of the present application to cast a variety of parts with complex structures and complex cavities, and can achieve higher precision and details. In particular, in the production of castings that require hollow or inner cavities (such as pipes, channels, etc.), the combination of sand cores provides greater flexibility. Multiple sand cores combined together can accurately form the required internal shape, reduce secondary processing after casting, reduce process and processing costs, and effectively improve the overall efficiency of casting production. By forming a mold with multiple sand cores, molding in one go, simplifying the design and shortening the manufacturing cycle.

[0066] The manufacturing method of the casting adopts a vacuum centrifugal casting process, and vacuum adsorption technology is used during centrifugal casting. During vacuum adsorption, the mold composed of sand cores is placed on a centrifugal casting machine, and the mold is evacuated and the vacuum degree is maintained, so that the cavity is in a negative pressure state. During centrifugal casting, the centrifugal casting machine is started, and after the centrifugal casting machine rotates to a preset speed, the molten steel in the pouring and holding furnace is injected into the mold, so that the molten steel fully fills the cavity to form a casting.

[0067] By vacuuming, it is ensured that there is no air or bubbles in the cavity, avoiding the formation of pores or other defects due to the presence of gas during the pouring process. Vacuum adsorption can effectively enhance the fluidity and wettability of molten steel in the cavity, ensuring that the molten steel can quickly and evenly fill every detail of the cavity, which is particularly suitable for the production of complex-shaped castings and thin-walled structures.

[0068] Centrifugal force helps drive the molten steel along the walls of the mold, allowing it to quickly and evenly fill the entire cavity. Due to the centrifugal force, the casting is usually denser and has fewer pores and other defects.

[0069] By combining vacuum adsorption with centrifugal pouring, the fluidity of molten steel during the pouring process is improved, and the filling capacity is stronger, so that even in a narrow cavity, the mold can be filled well to form a thin wall 10. For large or complex cavity castings, fast filling can also be guaranteed, which improves the quality of the castings and improves production efficiency.

[0070] like Fig.10As shown, the sand core 40 includes at least one inner core 41 and at least two outer cores 42. The outer surface of the inner core 41 is the same as the inner contour of the cavity 20. The inner core 41 and the outer core 42 together form a cavity, and the shape of the cavity is consistent with the shape of the casting to be produced. A pouring port 43 is formed between two adjacent outer cores 42 to allow molten steel to flow in during the pouring process.

[0071] The casting, vehicle and casting manufacturing method of the present application effectively reduce the weight of the casting by setting the main body of the casting as a thin wall 10, which is conducive to realizing the lightweight design of the product. At the same time, the thin wall 10 surrounds a hollow cavity 20, and at least a part of the cross section of the cavity 20 in the extension direction is a closed structure, so that a closed cavity is formed in the casting, which improves the rigidity and strength of the casting. In addition, since the casting of the present application is formed by casting in one piece, this manufacturing method simplifies the production process and improves production efficiency.

[0072] It should be noted that the technical solutions or technical features described in the above embodiments can be combined or supplemented with each other without causing conflicts. The scope of protection of this application is not limited to the precise structures described in the above embodiments and shown in the drawings; all modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of this application should be included in the scope of protection of this application.

Claims

1. A casting, characterized in that: The main body is formed by thin walls, which surround at least one hollow cavity. The cavity has an extension direction, and at least a part of the cross section of the cavity in the extension direction is a closed structure.

2. The casting according to claim 1, characterized in that The casting is made by vacuum centrifugal casting process, and vacuum adsorption technology is used during centrifugal casting.

3. The casting according to claim 1, characterized in that The thin wall includes an outer wall, the outer wall surrounds the cavity, and the outer wall includes a plurality of cavity surfaces, and the plurality of cavity surfaces may be at least two planes, curved surfaces, or a combination of a plane and a curved surface.

4. The casting according to claim 3, characterized in that The thin wall further includes a partition wall, which is located in the cavity and has two ends connected to the outer wall. The partition wall divides the cavity into a plurality of closed sub-cavities.

5. The casting according to claim 3, characterized in that The thin wall further includes a connecting wall, and the connecting wall is located outside the cavity and connected to the outer wall.

6. The casting according to claim 5, characterized in that The cavity includes a first cavity and a second cavity which are separately arranged, and two ends of the connecting wall are respectively connected to an outer wall of the first cavity and an outer wall of the second cavity.

7. The casting according to claim 5, wherein the connecting wall is a plane, a curved surface or a combination of a plane and a curved surface, and the connecting wall can form a semi-enclosed cavity.

8. The casting according to claim 3, characterized in that The cavity further includes a third cavity and a fourth cavity which are arranged to intersect each other; the third cavity and the fourth cavity share the outer wall at the intersection.

9. The casting according to claim 3, characterized in that The thin wall also includes a first reinforcing rib located in the cavity, wherein the first reinforcing rib has the same extension direction as the cavity and a length less than the extension length of the cavity; one side of the first reinforcing rib is connected to the outer wall, and the other side thereof is disconnected from the outer wall.

10. The casting according to claim 9, characterized in that The thin wall further includes a second reinforcing rib located in the cavity, wherein the second reinforcing rib is arranged perpendicularly or obliquely to the first reinforcing rib; one side of the second reinforcing rib is connected to the outer wall, and the other side opposite thereto is disconnected from the outer wall.

11. The casting according to claim 1, characterized in that The thin wall further includes an end wall, which is arranged at at least one end of the extending direction of the cavity, and the end wall partially or completely closes the end surface of the cavity.

12. The casting according to claim 1, characterized in that A local thickening structure is formed on the thin wall; and a penetrating forming hole is opened on the local thickening structure.

13. The casting according to claim 1, characterized in that The thickness of the thin wall can be variable; the minimum thickness of the thin wall is 0.8 mm; and / or the maximum thickness of the thin wall is 2.5 mm.

14. The casting according to claim 1, characterized in that The material of the casting is steel.

15. A vehicle, characterized in that: Comprising the casting as claimed in any one of claims 1-14.

16. A method for manufacturing a casting, characterized in that: The casting is formed by thin walls, which enclose at least one hollow cavity. The cavity has an extension direction, and at least a part of the cross-section of the cavity in the extension direction is a closed structure; the manufacturing method adopts a vacuum centrifugal casting process, and vacuum adsorption technology is used during centrifugal casting; the manufacturing method uses a sand core as a mold.

17. The method for manufacturing a casting according to claim 16, characterized in that: The sand core comprises at least one inner core and at least two outer cores, the outer surface of the inner core is the same as the inner contour of the cavity, and a pouring port is formed between two adjacent outer cores.

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