Method for producing a wheel hub by casting and forging and wheel hub

Abstract

The application provides a method for producing a hub by casting and forging and the hub, and the method comprises the following steps: a hub casting is prepared by casting, the hub casting comprises spokes, a hollow hole is reserved in the area where the spokes are located, the hollow hole penetrates the spokes along the axial direction of the hub casting, and the position, number and shape of the hollow hole are consistent with the vent holes on the final hub product; the hub casting with the hollow hole is placed in a die forging die, the upper die of the die forging die is provided with an upper concave hole part corresponding to the position of the hollow hole, and the lower die is provided with a lower convex part corresponding to the position of the hollow hole; when the die is closed, the lower convex part penetrates the hollow hole and is inserted into the upper die concave hole; when the die is forged, the spoke area bears the forging pressure, and the hollow area does not bear the forging pressure. The application has the effects of obviously improving the material utilization rate and reducing the forging pressure and equipment weight in the forging process.

Description

Technical Field

[0001] This invention belongs to the field of mold manufacturing technology, and in particular relates to a method for producing wheel hubs by combining casting and forging, and the wheel hub itself. Background Technology

[0002] The main manufacturing methods for wheel hubs include gravity casting, low-pressure casting, casting spinning, and forging spinning.

[0003] Wheel hubs produced by pure casting methods (such as low-pressure casting) have a high degree of freedom in forming and can be made into complex hollow shapes, but the as-cast structure is coarse and there are shrinkage and porosity defects. Their mechanical properties (tensile strength is generally 200-250MPa) are difficult to meet the requirements of high-end models for lightweighting and high strength.

[0004] Wheel hubs produced by pure forging (such as forging spinning) have fine grains, complete streamlines, and excellent mechanical properties (tensile strength ≥350MPa). However, they have the following prominent problems: First, forging blanks are usually solid round cakes or extruded bars. The hollow areas of the wheel hub (such as the ventilation holes of the spokes) are entirely formed by subsequent machining, and the material utilization rate is only 60% to 70%. Second, the forging equipment has a large tonnage (requiring 30,000kN to 50,000kN), short die life (5,000 to 10,000 die cycles), and high cost.

[0005] To address the aforementioned contradictions, attempts at combined casting and forging processes have emerged in recent years. For example, one related technology discloses an aluminum alloy wheel hub casting and forging device that first casts the blank and then forges it. However, this approach has significant shortcomings: the cast blank is a solid or near-solid structure, and the hollow areas still need to be formed through machining after forging, failing to solve the problem of low material utilization. If the hollow areas are formed directly during casting, they are prone to deformation or filling during die forging, leading to product scrap. Furthermore, in existing combined casting and forging schemes, the casting mold and forging mold are often shared or have similar structures, making it difficult to effectively protect the hollow features formed during casting during forging. Another related technology discloses a split wheel hub forging mold with a gap-fitting structure, but its purpose is to achieve the forming of wheel rims of different sizes by changing the mold cavity, not to protect the hollow features of the cast blank during forging.

[0006] Therefore, how to retain the hollow features formed by casting to greatly improve material utilization, give full play to the strengthening effect of forging to improve mechanical properties, reduce equipment tonnage and mold costs, and ensure that the hollow features do not deform or fill during the die forging process is a technical problem that urgently needs to be solved in this field. Summary of the Invention

[0007] This invention provides a method for producing wheel hubs using a combination of casting and forging, and the resulting wheel hub. The technical solution of this invention is shown below: On the one hand, a method for combined casting and forging production of wheel hubs is provided, including: Step S1: Prepare a wheel hub casting by casting. The wheel hub casting includes spokes. A hollow hole is reserved in the area where the spokes are located. The hollow hole passes through the spokes along the axial direction of the wheel hub casting. The position, number and shape of the hollow hole are consistent with the ventilation holes on the final wheel hub product. Step S2: Place the wheel hub casting with the hollowed-out hole into the forging mold. The upper mold of the forging mold has an upper recessed hole corresponding to the position of the hollowed-out hole, and the lower mold has a lower protrusion corresponding to the position of the hollowed-out hole. When the mold is closed, the lower protrusion passes through the hollowed-out hole and inserts into the recessed hole of the upper mold. During die forging, the spoke area bears the forging pressure, while the hollowed-out area does not. After die forging, the hollowed-out hole retains the topological shape formed during casting, and its hole diameter change rate is ≤5%.

[0008] In one optional embodiment, in step S2, the forging die is a split-side die structure, and the side dies close from both sides when the die is closed, for producing wheel hub blanks with a lower rim. Alternatively, the forging die may be an integral edge die structure, used to produce wheel hub blanks without a lower rim or blanks for spinning.

[0009] In an optional embodiment, in step S2, a clearance fit is formed between the lower protrusion and the wall of the hollow hole, with a single-sided clearance of 0.01mm to 0.2mm; In one optional embodiment, in step S1, the upper surface profile of the wheel hub casting is consistent with the upper mold surface features of the forging die in step S2. The lower surface profile of the wheel hub casting is consistent with the lower mold surface features of the forging die described in step S2; In an optional embodiment, 5. the method for producing wheel hubs by casting and forging according to claim 1, characterized in that: the casting method includes low-pressure casting, die casting, and sand casting; The casting pressure of the low-pressure casting method is 0.1 MPa to 0.5 MPa; The casting pressure of the die casting method is 15MPa to 120MPa; The sand casting method is gravity casting, without external casting pressure.

[0010] The connection methods between steps S1 and S2 include casting directly to die forging, casting followed by homogenization and then to die forging, and casting followed by cooling and then reheating and then to die forging. In an optional embodiment, in the casting direct delivery forging method, the cooling rate of the casting during the transfer process is determined according to the thickness characteristics and material thermophysical parameters of the wheel hub casting. The demolding temperature of the wheel hub casting is determined by reverse calculation based on the appropriate forging temperature required for forging, so that the wheel hub casting is directly transferred to the forging mold for forging without reheating after demolding. In the casting-after-hoisting-and-forging-into-die-forging method, after the wheel hub casting is demolded, it enters the homogenizing furnace and is kept at a temperature of 10 to 30 minutes in the homogenizing furnace to stabilize the temperature of the wheel hub casting within the appropriate forging temperature range before die forging. In the casting, cooling, reheating, and then die forging process, the wheel hub casting is cooled to room temperature after demolding, then reheated to the appropriate forging temperature range before die forging.

[0011] In an optional embodiment, in step S2, when the wheel hub casting is placed into the forging mold, dual positioning is achieved by the outer ring positioning surface on the lower mold cooperating with the outer circumference of the wheel hub casting, and the central positioning mandrel on the lower mold cooperating with the central hole of the wheel hub casting, with a positioning accuracy of ±0.1mm.

[0012] On the other hand, embodiments of the present invention provide a wheel hub, which is prepared by any of the above-described casting and forging combined production methods for wheel hubs.

[0013] This invention achieves a functional synergy between the casting and forging processes through the coordinated use of three technical features: pre-reserved hollow holes during casting, the lower protrusion passing through the hollow holes and inserting into the upper recessed holes, and the hollowed-out area not bearing forging pressure. The casting process provides the forging process with a channel for the lower protrusion to pass through and a space for radial support. The forging process distributes and transmits forging pressure through the lower protrusion passing through the hollow holes, ensuring that the hollowed-out area does not bear forging pressure, thereby protecting the hollowed-out features formed during the casting process from damage. Attached Figure Description

[0014] The above and other objects, features and advantages of this disclosure will become more apparent from the accompanying drawings, in which like reference numerals generally denote like parts.

[0015] Figure 1 This is a schematic diagram of a method for producing wheel hubs by casting and forging according to an embodiment of the present invention. Figure 2 This is a schematic diagram of the structure of the casting prepared according to an embodiment of the present invention.

[0016] Figure 3 This is a schematic diagram of the structure of the wheel hub blank prepared according to an embodiment of the present invention.

[0017] Figure 4This is a schematic diagram of the structure of a spun blank with a lower edge (split edge die during forging) provided in an embodiment of the present invention.

[0018] Figure 5 This is a schematic diagram of the structure of a blank without a lower edge (splitting edge die during forging) provided in an embodiment of the present invention. Detailed Implementation

[0019] Embodiments of the present disclosure will now be described in more detail with reference to the accompanying drawings. While embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that the present disclosure will be thorough and complete, and will fully convey the scope of the present disclosure to those skilled in the art.

[0020] The terms used herein include, and their variations thereof, open-ended meanings, including but not limited to. Unless otherwise stated, terms or representations are not limited to. Terms based on or derived from are at least partially based on. Terms one example embodiment and one embodiment represent at least one example embodiment. Terms another embodiment represent at least one additional embodiment. Terms first, second, etc., may refer to different or the same objects. Other explicit and implicit definitions may also be included below.

[0021] Please see Figure 1 This invention provides a method for the combined casting and forging production of wheel hubs, comprising: Step S1: Prepare the wheel hub casting by casting. The wheel hub casting includes the spokes. A hollow hole is reserved in the area where the spokes are located. The hollow hole passes through the spokes along the axial direction of the wheel hub casting. The position, number and shape of the hollow hole are consistent with the ventilation holes on the final wheel hub product.

[0022] It should be noted that the wheel hub casting refers to the direct product of the casting process, i.e., the intermediate blank before the die forging process. The spokes are a component of the wheel hub casting, located between the central area and the rim, serving as the supporting structure connecting the central mounting plate and the outer rim. The perforated holes are through holes pre-drilled in the area of ​​the spokes during the casting process, extending through the spokes along the axial direction of the wheel hub casting (i.e., the direction of the wheel hub's rotation axis). The position, number, and shape of these perforated holes correspond to the ventilation holes on the final wheel hub product. For example, for a five-spoke wheel hub product, a ventilation hole is pre-drilled between each of the five spokes during casting, with their position, number, and shape corresponding one-to-one with the final product.

[0023] In actual implementation, taking the A356 aluminum alloy five-spoke wheel as an example, low-pressure casting is used, with a pouring temperature of 720℃, a casting pressure of 0.3MPa, a holding time of 30s, a cooling rate of 2.5℃ / s, and a casting demolding temperature of 420℃. After casting, five hollow holes are formed on the spokes of the wheel casting. The position, number, and shape of these five hollow holes are consistent with the five ventilation holes on the final wheel product.

[0024] Step S2: Place the wheel hub casting with the hollowed-out hole into the forging mold. The upper mold of the forging mold has an upper recessed hole corresponding to the position of the hollowed-out hole, and the lower mold has a lower protrusion corresponding to the position of the hollowed-out hole. When the mold is closed, the lower protrusion passes through the hollowed-out hole and inserts into the recessed hole of the upper mold. During die forging, the spoke area bears the forging pressure, while the hollowed-out area does not. After die forging, the hollowed-out holes retain the topological shape formed during casting, with a hole diameter change rate ≤5%. Please refer to [link to relevant documentation]. Figure 2 and Figure 3 As shown, Figure 2 This is a schematic diagram of the structure of the casting prepared according to an embodiment of the present invention. Figure 3 This is a schematic diagram of the structure of the wheel hub blank prepared according to an embodiment of the present invention.

[0025] It should be noted that the forging die is a specialized die used for forging cast blanks. The upper recessed hole is a recessed structure located on the parting surface of the upper forging die, and its position corresponds one-to-one with the position of the hollowed-out holes on the wheel hub casting, used to accommodate the insertion of the lower protrusion when the die is closed. The lower protrusion is a protruding structure fixedly located on the parting surface of the lower forging die, and its position also corresponds one-to-one with the position of the hollowed-out holes. The number of lower protrusions is the same as the number of hollowed-out holes; for example, a five-spoke wheel hub has five lower protrusions, evenly distributed along the circumference of the die. The height of the lower protrusion is configured to be greater than the wall thickness at the hollowed-out holes of the wheel hub casting, to ensure that the lower protrusion can pass through the hollowed-out holes and insert into the upper recessed hole when the die is closed.

[0026] In practical implementation, taking a five-spoke wheel hub as an example, five lower protrusions are fixedly set on the lower parting surface of the forging die, and five upper recessed holes are correspondingly set on the upper parting surface of the die. Each lower protrusion and upper recessed hole corresponds one-to-one with the position of the five hollow holes on the wheel hub casting. The material of the lower protrusions is hot work die steel H13, with an overall hardness of HRC 44-48, and the surface is nitrided with a nitriding layer thickness of 0.2mm.

[0027] During mold closing, the lower protrusion passes through the perforated hole and inserts into the upper recessed hole. Its working principle is as follows: the lower protrusion enters upwards from the lower end of the perforated hole, passing through the entire hole, and its top end enters the upper recessed hole of the upper mold. At this time, the wall of the perforated hole surrounds the outer circumference of the lower protrusion, providing radial support. Because the lower protrusion passes through the perforated hole and inserts into the upper recessed hole, the forging pressure transmission path is: upper slide of the press, upper mold, upper mold surface, forging, lower mold surface, lower mold, press worktable. This pressure transmission path bypasses the upper mold recessed hole and the lower mold protrusion in the perforated area, meaning the perforated area does not bear forging pressure, thus facilitating a decrease in forging pressure.

[0028] After die forging, the hollowed-out hole retains the topological shape formed during casting, and its hole outline dimension change rate is ≤5%.

[0029] The topological shape refers to the number, relative position, and basic shape outline of the perforated holes, i.e., the qualitative characteristics of the perforated holes. The hole outline size change rate refers to the change range of the hole outline size after die forging relative to the hole outline size in the casting state before die forging. The calculation formula is: |hole diameter after die forging - hole outline size before die forging| / hole outline size before die forging × 100%.

[0030] This invention achieves a functional synergy between the casting and forging processes through the coordinated use of three technical features: pre-reserved hollow holes during casting, the lower protrusion passing through the hollow holes and inserting into the upper recessed holes, and the hollowed-out area not bearing forging pressure. The casting process provides the forging process with a channel for the lower protrusion to pass through and a space for radial support. The forging process distributes and transmits forging pressure through the lower protrusion passing through the hollow holes, ensuring that the hollowed-out area does not bear forging pressure, thereby protecting the hollowed-out features formed during the casting process from damage.

[0031] Please see Figure 4 and Figure 5 In one optional embodiment, in step S2, the forging die is a split-type side die structure, which closes from both sides when the die is closed, and is used to produce a blank for spinning wheel hub with a lower rim; or, the forging die is an integral side die structure, and is used to produce a blank for spinning wheel hub without a lower rim.

[0032] It should be noted that a split-type side mold refers to a mold whose side mold portion consists of two or more separable modules, closing from both sides during mold assembly and opening to both sides during mold separation. The lower wheel rim refers to the rim portion of the wheel hub near the outer side of the vehicle (the brake disc side). A one-piece side mold refers to a side mold that is a single, integral structure, without segments.

[0033] In practice, when producing wheel hub blanks with a lower rim, a split-die structure is used. During forging, the dies close from both sides to form a complete cavity. After forging, the dies open to both sides for easy demolding. When producing wheel hub blanks without a lower rim or blanks for spinning, an integral-die structure is used.

[0034] The split-die structure enables the production of complex wheel hub blanks with lower rims. The dies close and open from both sides, solving the problem of difficult demolding of products with lower rims. The integral-die structure is simple in structure, has good rigidity, and low manufacturing cost, making it suitable for the production of wheel hub blanks without lower rims or blanks for spinning. The selection of two die structures allows this invention to adapt to the production needs of different types of wheel hub products, expanding the scope of process applicability.

[0035] In an optional embodiment, in step S2, a clearance fit is formed between the lower protrusion and the wall of the hollow hole, with a single-sided clearance of 0.01mm to 0.2mm.

[0036] It should be noted that clearance fit refers to a fit in which there is a gap between the outer surface of the lower protrusion and the inner wall of the perforated hole. Single-sided clearance refers to the clearance distance on one side between the outer surface of the lower protrusion and the inner surface of the hole wall.

[0037] In practice, the clearance on one side can be 0.1mm. As other options, the clearance on one side can be 0.05mm, 0.08mm, 0.12mm or 0.15mm.

[0038] The single-sided clearance is controlled between 0.01mm and 0.2mm. This clearance ensures that the lower protrusion can pass smoothly through the hollow hole without getting stuck when the mold is closed, and also prevents the molten metal from being squeezed into the mating surface during the forging process, which could cause the lower protrusion to stick to the hole wall or affect demolding. At the same time, this clearance ensures that the lower protrusion provides effective radial support to the hole wall. If the clearance is too large, the support will be insufficient, and the hollow hole may deform during the forging process; if the clearance is too small, the protrusion will have difficulty passing through, and may even damage the casting or mold.

[0039] In an optional embodiment, in step S1, the upper surface profile of the wheel hub casting is consistent with the upper mold surface feature of the forging die in step S2; the lower surface profile of the wheel hub casting is consistent with the lower mold surface feature of the forging die in step S2.

[0040] It should be noted that the profile refers to the three-dimensional geometric shape of the surface of the wheel hub casting or mold. Feature consistency means that the curvature and shape of the casting surface and the mold surface match, that is, after the casting is placed in the mold, the upper and lower surfaces of the casting can fit tightly with the upper and lower model surfaces of the mold.

[0041] In actual implementation, the upper surface of the wheel hub casting is the surface that contacts the upper model surface of the mold, and its characteristics are consistent with those of the upper model surface; the lower surface of the wheel hub casting is the surface that contacts the lower model surface of the mold, and its characteristics are consistent with those of the lower model surface.

[0042] The consistency between the casting profile and the mold profile ensures a tight fit between the casting and the mold surface after placement, preventing slippage or displacement during forging due to mismatched profiles. This guarantees the forming accuracy and positional accuracy of the cutouts. Furthermore, a good profile fit facilitates the uniform transmission of forging pressure, preventing localized stress concentrations that could lead to casting cracking or mold damage.

[0043] In one optional embodiment, the casting method includes low-pressure casting, die casting, and sand casting. The casting pressure of the low-pressure casting method is 0.1 MPa to 0.5 MPa; The casting pressure of the die casting method is 15MPa to 120MPa; The sand casting method is gravity casting, without external casting pressure.

[0044] The casting pressure for low-pressure casting can be 0.1MPa, 0.2MPa, 0.4MPa or 0.5MPa, the holding time can be 10s, 20s, 40s, 50s or 60s, and the cooling rate can be 1℃ / s, 2℃ / s, 3℃ / s, 4℃ / s or 5℃ / s.

[0045] In one optional embodiment, the connection between step S1 and step S2 includes casting direct delivery to die forging, casting followed by homogenization and then delivery to die forging, and casting followed by cooling and then reheating and then delivery to die forging. In this embodiment of the invention, the method for producing wheel hubs using a combined casting and forging process can include different approaches. For example, a wheel hub casting already containing hollowed-out holes can be directly sent for forging, without needing to heat the hollowed-out holes again during the forging process. Alternatively, the wheel hub casting already containing hollowed-out holes can be uniformly heated before being sent for forging.

[0046] In the casting direct delivery forging method, the cooling rate of the casting during the transfer process is determined based on the thickness characteristics and material thermophysical parameters of the wheel hub casting. The demolding temperature of the wheel hub casting is determined by reverse calculation based on the appropriate forging temperature required for forging, so that the wheel hub casting can be directly transferred to the forging mold for forging without reheating after demolding. In the casting-after-hoisting-and-forging-into-die-forging method, after the wheel hub casting is demolded, it enters the homogenizing furnace and is kept at a temperature of 10 to 30 minutes in the homogenizing furnace to stabilize the temperature of the wheel hub casting within the appropriate forging temperature range before die forging. In the casting, cooling, reheating, and then die forging process, the wheel hub casting is cooled to room temperature after demolding, then reheated to the appropriate forging temperature range before die forging.

[0047] In the direct-feed forging method described above, there is a definite relationship between the casting demolding temperature and the temperature drop during the transfer process. Given the transfer time, ambient temperature, and casting dimensions, based on the principle of thermal balance, the temperature drop rate of the wheel hub casting is related to the casting wall thickness, material thermal properties, and environmental heat transfer conditions. Taking an A356 aluminum alloy wheel hub casting as an example: the wheel hub casting weighs 15kg, the average wall thickness of the spoke area is 15mm, the transfer time is 25 seconds, and the ambient temperature is 25℃. Through thermal balance calculations, when the demolding temperature is 367.5℃, the casting temperature drops to 350℃ after 25 seconds of transfer, which precisely meets the lower limit requirement for the suitable forging temperature. Therefore, when this specification of wheel hub casting is transferred to the forging die within 25 seconds, the demolding temperature must not be lower than 367.5℃. For different specifications of wheel hub castings or different transfer conditions, the required lower limit of the demolding temperature can be recalculated based on the same thermal balance principle. In production practice, a safety margin of 10℃ to 20℃ can be added to the calculated value based on actual working conditions.

[0048] The suitable forging temperature range mentioned in this invention refers to the temperature range within which aluminum alloy wheel hub castings can undergo sufficient plastic deformation without cracking during die forging, which has been determined through experiments to be 350℃~450℃. Below 350℃, the material's plasticity decreases sharply, and direct die forging is extremely prone to cracking; above 450℃, overheating or burning may occur, damaging the material's properties.

[0049] This invention features stable low-pressure casting filling, avoiding the problem of gas entrapment and porosity during die casting; sufficient feeding reduces shrinkage cavities and other defects; and the casting has a dense structure, providing high-quality billets for subsequent die forging and ensuring that it does not crack due to casting defects during the forging process. Simultaneously, by controlling the cooling rate and demolding temperature within a suitable range, it ensures that the casting has sufficient plasticity temperature (350℃~480℃) upon demolding, creating conditions for subsequent direct die forging using residual casting heat.

[0050] It should be noted that sand casting refers to a method of casting using molding sand as the molding material to prepare the mold. Sand-cast parts cool more slowly and have coarser grains; therefore, it is necessary to appropriately increase the forging temperature and forging ratio to achieve sufficient microstructure refinement.

[0051] In practice, the pouring temperature for sand casting can be 720℃, and the demolding temperature can be 450℃. The forging temperature is 30℃ higher than that for low-pressure casting; for example, if the forging temperature for low-pressure casting is 400℃, the forging temperature for sand casting is 430℃. The forging ratio can be 1.3.

[0052] Sand casting can be used as a case of non-direct-feed ingot casting: after the sand casting cools and is demolded, the gate is cleaned and the mold is put into the heating furnace for casting.

[0053] This invention uses sand casting molds, which are low in cost and suitable for small-batch production. By appropriately increasing the forging temperature and forging ratio, the shortcomings of coarse grains in sand castings can be compensated, and good mechanical properties can still be obtained.

[0054] In an optional embodiment, in step S2, when the wheel hub casting is placed into the forging mold, dual positioning is achieved by the outer ring positioning surface on the lower mold cooperating with the outer circumference of the wheel hub casting, and the central positioning mandrel on the lower mold cooperating with the central hole of the wheel hub casting, with a positioning accuracy of ±0.1mm.

[0055] It should be noted that the outer locating ring is an annular locating surface set on the parting surface of the lower mold, which mates with the outer circumferential surface of the wheel hub casting. The center locating mandrel is a locating shaft set at the center of the lower mold, which mates with the center hole of the wheel hub casting (i.e., the mounting hole at the center of the wheel hub). Dual positioning refers to using both outer ring positioning and center hole positioning simultaneously to determine the position of the casting in the mold. Positioning accuracy ±0.1mm means that the positional deviation of the casting in the mold is controlled within ±0.1mm.

[0056] In actual implementation, the positioning gap between the outer ring positioning surface and the outer circumference of the wheel hub casting is 0.2mm, and the positioning gap between the central positioning mandrel and the central hole of the wheel hub casting is 0.15mm.

[0057] This invention employs dual positioning: outer ring positioning provides coarse positioning over a wide range, while center hole positioning provides precise fine positioning. The combination of these two methods ensures the casting's unique and accurate position within the mold, achieving a positioning accuracy of ±0.1mm. This precise positioning guarantees that each lower protrusion can accurately pass through each hollowed-out hole and insert into the corresponding upper recessed hole, preventing damage to the mold or casting due to collisions between the protrusions and the hole walls caused by positional deviations. Simultaneously, it ensures that the positional accuracy of the hollowed-out holes after die forging is consistent with the casting state.

[0058] The various embodiments of this disclosure have been described above. These descriptions are exemplary and not exhaustive, nor are they limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments. The terminology used herein is chosen to best explain the principles, practical application, or technical improvements to the embodiments in the market, or to enable others skilled in the art to understand the embodiments disclosed herein.

Claims

1. A method for producing wheel hubs using a combination of casting and forging, characterized in that, include: Step S1: Prepare a wheel hub casting by casting. The wheel hub casting includes spokes. A hollow hole is reserved in the area where the spokes are located. The hollow hole passes through the spokes along the axial direction of the wheel hub casting. The position, number and shape of the hollow hole are consistent with the ventilation holes on the final wheel hub product. Step S2: Place the wheel hub casting with the hollowed-out hole into the forging mold. The upper mold of the forging mold has an upper recessed hole corresponding to the position of the hollowed-out hole, and the lower mold has a lower protrusion corresponding to the position of the hollowed-out hole. When the mold is closed, the lower protrusion passes through the hollowed-out hole and inserts into the recessed hole of the upper mold. During die forging, the spoke area bears the forging pressure, while the hollowed-out area does not. After die forging, the hollowed-out hole retains the topological shape formed during casting, and its hole diameter change rate is ≤5%.

2. The method for producing wheel hubs by combined casting and forging according to claim 1, characterized in that: In step S2, the forging die is a split-type side die structure. When the die is closed, the side dies close from both sides to produce wheel hub blanks with a lower rim. Alternatively, the forging die may be an integral edge die structure, used to produce wheel hub blanks without a lower rim or blanks for spinning.

3. The method for producing wheel hubs by combined casting and forging according to claim 1, characterized in that: In step S2, a clearance fit is formed between the lower protrusion and the wall of the hollow hole, with a single-sided clearance of 0.01mm to 0.2mm.

4. The method for producing wheel hubs by combined casting and forging according to claim 1, characterized in that: In step S1, the upper surface profile of the wheel hub casting is consistent with the upper mold surface features of the forging die in step S2; The lower surface profile of the wheel hub casting is consistent with the lower mold surface features of the forging die described in step S2.

5. The method for producing wheel hubs by combined casting and forging according to claim 1, characterized in that: The casting methods include low-pressure casting, die casting, and sand casting. The casting pressure of the low-pressure casting method is 0.1 MPa to 0.5 MPa; The casting pressure of the die casting method is 15MPa to 120MPa; The sand casting method is gravity casting, without external casting pressure.

6. The method for producing wheel hubs by combined casting and forging according to claim 1, characterized in that, The connection methods between steps S1 and S2 include casting directly to die forging, casting followed by homogenization and then to die forging, and casting followed by cooling and then reheating and then to die forging. In the casting direct delivery forging method, the cooling rate of the casting during the transfer process is determined based on the thickness characteristics and material thermophysical parameters of the wheel hub casting. The demolding temperature of the wheel hub casting is determined by reverse calculation based on the appropriate forging temperature required for forging, so that the wheel hub casting can be directly transferred to the forging mold for forging without reheating after demolding. In the casting-after-hoisting-and-forging-into-die-forging method, after the wheel hub casting is demolded, it enters the homogenizing furnace and is kept at a temperature of 10 to 30 minutes in the homogenizing furnace to stabilize the temperature of the wheel hub casting within the appropriate forging temperature range before die forging. In the casting, cooling, reheating, and then die forging process, the wheel hub casting is cooled to room temperature after demolding, then reheated to the appropriate forging temperature range before die forging.

7. The method for producing wheel hubs by combined casting and forging according to claim 1, characterized in that: When the casting temperature is ≤350℃ in step S1, the casting is reheated to the appropriate forging temperature and held for 10min to 30min before step S2, and then forging is performed.

8. The method for producing wheel hubs by combined casting and forging according to claim 1, characterized in that: In step S2, when the wheel hub casting is placed into the forging mold, dual positioning is achieved by the outer ring positioning surface on the lower mold cooperating with the outer circumference of the wheel hub casting, and the central positioning mandrel on the lower mold cooperating with the central hole of the wheel hub casting, with a positioning accuracy of ±0.1mm.

9. A wheel hub, characterized in that, The wheel hub is produced using the casting and forging combined production method described in any one of claims 1-8.

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