Hybrid material wheel hub, method of processing and vehicle

Abstract

The application belongs to the technical field of wheel hub, and provides a mixed material wheel hub, a processing method and a vehicle. A high-performance aluminum-magnesium alloy material is used in the spoke part which bears the most complex stress, so that the high fatigue strength and high rigidity of the whole wheel hub are ensured, and the performance index approaches that of a forged wheel hub. In the rim part which is mainly pressure-bearing and heat-dissipating and has a complex shape, a cast aluminum alloy material is used, so that the advantages of good casting performance and high cost performance are fully exerted. A composite connecting mode combining mechanical interlocking and welding is adopted between the spoke and the rim, the mechanical interlocking structure provides strong torsion resistance and accurate centering, and interface fretting wear is avoided.

Description

Technical Field

[0001] This invention belongs to the field of wheel hub technology, and particularly relates to a hybrid material wheel hub, a processing method, and a vehicle. Background Technology

[0002] The statements in this section are merely background information related to the present invention and do not necessarily constitute prior art.

[0003] Wheel hubs are critical safety and performance components in a vehicle's driving system, directly affecting the vehicle's safety, handling, and fuel economy. Currently, automotive wheel hubs are mainly divided into two categories: steel wheel hubs and aluminum alloy wheel hubs. Among them, aluminum alloy wheel hubs, due to their superior overall performance, have gradually become the mainstream product in the market.

[0004] The wheel spokes and rim experience significantly different stress patterns under operating conditions. The spokes primarily bear bending stress, torsional stress, and alternating fatigue stress from vehicle loads, placing extremely high demands on the material's strength, fatigue limit, and rigidity. In contrast, the rim primarily bears circumferential stress generated by tire pressure, road impact loads, and braking thermal loads, emphasizing the material's toughness, casting fluidity, impact resistance, and thermal conductivity. Traditional single-piece A356 cast wheel hubs, in order to meet the strength requirements of the spokes, often result in excessive performance in the rim area, or the spokes become a weak point in terms of strength due to overall weight reduction considerations. Summary of the Invention

[0005] To overcome the shortcomings of the prior art, the present invention provides a hybrid material wheel hub, processing method and vehicle. By dividing the material into aluminum-magnesium alloy spokes and cast aluminum alloy rims, and combining mechanical interlocking and welding composite connection method, the weight of the wheel hub is significantly reduced while achieving high strength and fatigue life close to that of forged wheel hubs.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: In a first aspect, the present invention provides a hybrid material wheel hub, comprising spokes and a rim, wherein the spokes are made of aluminum-magnesium alloy and the rim is made of cast aluminum alloy; a mechanically interlocking structure is provided at the connection interface between the spokes and the rim, and a continuous bonding layer is welded between the spokes and the rim.

[0007] Preferably, the mechanical interlocking structure is an end tooth structure or a spiral sawtooth structure that is evenly distributed along the circumference.

[0008] Preferably, a continuous bonding layer is formed by solid-state welding to metallurgically bond the spokes and the rim; the solid-state welding is inertial friction welding or friction stir welding.

[0009] Preferably, the spokes and the rim are formed into an integral component by low-pressure casting and heat treatment.

[0010] Preferably, the aluminum-magnesium alloy material is a 5000 series aluminum alloy; the cast aluminum alloy material is an aluminum-silicon series cast aluminum alloy.

[0011] Secondly, the present invention provides a method for processing hybrid material wheel hubs, comprising: The spokes are independently manufactured from aluminum-magnesium alloy, and the first mechanical interlocking structure is machined on the spoke connection end face; The wheel rim is independently manufactured from cast aluminum alloy material, and a second mechanical interlocking structure that matches the first mechanical interlocking structure is machined on the connecting end face of the wheel rim. The spokes and the rim are positioned and pre-assembled using the first mechanical interlocking structure and the second mechanical interlocking structure; The pre-assembled wheel spokes are welded to the wheel rim to form a continuous bonding layer.

[0012] Preferably, the aluminum-magnesium alloy sheet or forging blank is CNC milled or forged to form the spoke body and the first mechanical interlocking structure; the wheel rim blank is formed by low-pressure casting, then the wheel rim blank is heat-treated, and finally the wheel rim connecting end face is machined to form the second mechanical interlocking structure. Preferably, the pre-assembled wheel spokes and wheel rim are welded together by solid-state welding to form a continuous bonding layer; the solid-state welding is inertial friction welding or friction stir welding.

[0013] Preferably, after the solid-state welding step, the welded area is further subjected to stress-relief annealing.

[0014] Thirdly, the present invention provides a vehicle that uses the above-mentioned hybrid material wheel hub, or a hybrid material wheel hub processed by the above-mentioned hybrid material wheel hub processing method.

[0015] The above one or more technical solutions have the following beneficial effects: In this invention, high-performance aluminum-magnesium alloy is used in the spokes, which bear the most complex stress, to ensure high fatigue strength and high rigidity of the wheel hub as a whole, with performance indicators approaching those of forged wheel hubs. In the rim, which has a complex shape and is mainly for bearing pressure and heat dissipation, cast aluminum alloy is used, giving full play to its advantages of good casting performance and high cost performance. The spokes and rim adopt a composite connection method combining mechanical interlocking and welding. The mechanical interlocking structure provides strong anti-torsional capacity and precise alignment, avoiding interface fretting wear.

[0016] Advantages of additional aspects of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0017] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0018] Figure 1 This is a schematic diagram of the overall structure of the hybrid material wheel hub in an embodiment of the present invention; Figure 2 This is a partial schematic diagram of the connection between the spokes and the rim in an embodiment of the present invention; Figure 3 This is a partial schematic diagram of the end tooth structure in an embodiment of the present invention; In the diagram, 1 is the spoke; 2 is the rim; 3 is the composite connection structure; 4 is the reverse snap structure; and 5 is the snap-fit ​​end teeth. Detailed Implementation

[0019] It should be noted that the following detailed descriptions are exemplary and intended to provide further illustration of the invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0020] It should be noted that the terminology used herein is for the purpose of describing particular implementations only and is not intended to limit the exemplary implementations of the present invention.

[0021] Where there is no conflict, the embodiments and features in the embodiments of the present invention can be combined with each other.

[0022] Example 1 In existing technologies, the manufacturing processes for aluminum alloy wheels mainly include casting (gravity casting, low-pressure casting) and forging. Low-pressure casting is currently the most widely used technology in the original equipment market. This process uses cast aluminum alloys such as A356.2, and the mold is filled under pressure, resulting in high casting density, a high degree of freedom in shape design, and good cost control. However, due to the limitations of the mechanical properties of the cast aluminum alloy material itself, especially the yield strength and fatigue strength, such wheels often require increased local wall thickness to meet strength standards, thus restricting the further realization of lightweight potential.

[0023] Forged aluminum alloy wheels (such as those made of 6061 aluminum alloy) are formed through forging, resulting in continuous metal flow lines and a fine grain structure. They possess extremely high specific strength and excellent fatigue performance, making them representative of high-performance wheels. However, the large investment in equipment, complex processes, and low material utilization rate lead to high manufacturing costs, hindering their widespread adoption in the mass market. Therefore, existing single-material wheel solutions suffer from the following technical drawbacks: Mismatch between material properties and component functions: The stress patterns of wheel spokes and rims differ significantly under working conditions. Wheel spokes primarily bear bending stress, torsional stress, and alternating fatigue stress from vehicle loads, requiring extremely high strength, fatigue limit, and rigidity of the material. In contrast, wheel rims primarily bear circumferential stress generated by tire pressure, road impact loads, and braking thermal loads, placing greater emphasis on the material's toughness, casting fluidity, impact resistance, and thermal conductivity. Traditional single-layer A356 cast wheel hubs, in order to meet the strength requirements of the spokes, often result in excessive performance in the rim area, or the spokes become a weak point in terms of strength due to overall weight reduction considerations.

[0024] The trade-off between lightweighting and cost: While forged wheels can achieve extreme lightweighting and high strength, they are expensive; low-pressure cast A356 wheels have controllable costs, but their lightweighting and mechanical properties have inherent limitations. Within a single material system, any performance improvement is often accompanied by a significant increase in cost.

[0025] Process limitations: A single casting process cannot achieve optimal performance matching for all parts of the same component. For example, the thick areas of the wheel spokes are prone to casting defects such as shrinkage porosity, which can become the initiation point for fatigue cracks.

[0026] Based on the aforementioned problems, this embodiment discloses a hybrid material wheel hub, such as... Figures 1-3 As shown, the wheel includes spokes 1 and rim 2. Spokes 1 are made of aluminum-magnesium alloy, and rim 2 is made of cast aluminum alloy. A mechanically interlocking structure is provided at the interface between spokes 1 and rim 2, and a continuous bonding layer is welded between the spokes and rim. The mechanically interlocking structure and the continuous bonding layer constitute a composite connection structure 3 between spokes 1 and rim 2.

[0027] As one specific implementation method, the mechanical interlocking structure is an end tooth structure or a spiral sawtooth structure that is evenly distributed along the circumference.

[0028] The specific form of the end tooth structure can be diversified. For example, cylindrical end teeth can be used, with their tooth shape being cylindrical or prismatic, arranged along the circumference, providing good circumferential positioning capability. Triangular sawtooth teeth with a large helix angle can also be used; this structure has a certain self-locking characteristic in the axial direction, and clamping can be achieved through relative rotation during assembly. Furthermore, a multi-dimensional curved surface interlocking structure can be used, where the tooth shape at the connection interface is no longer limited to simple geometry but adopts a complex curved surface profile, thus providing constraints simultaneously in multiple directions. To further enhance the torsional resistance and positioning accuracy of the connection, radial pins can be added to the connection interface as auxiliary positioning and force transmission elements. These pins are distributed along the circumference and embedded in corresponding holes in the spokes and rim, forming a second layer of mechanical locking.

[0029] like Figure 3As shown, the end tooth structure includes a reverse-locking structure 4 and a snap-fit ​​end tooth 5. The snap-fit ​​end tooth 5 is located on the connecting end face of the outer edge of the spoke 1 or the inner base of the rim 2, and is a tooth-shaped structure evenly distributed along the circumferential direction, used to provide precise circumferential positioning and transmit torque. The reverse-locking structure 4 is located on the mating end face of the inner base of the rim 2 or the outer edge of the spoke 1, and is a complementary tooth shape or snap-fit ​​feature that fully meshes with the snap-fit ​​end tooth 5.

[0030] The snap-fit ​​end teeth are a toothed structure evenly distributed along the circumference, with each tooth having a specific tooth angle and height. The entire end tooth structure provides precise circumferential positioning and torque transmission. The corresponding reverse-locking structure is located on the mating end face of the inner base of the rim or the outer edge of the spokes, and is a complementary toothed structure or interlocking feature that fully meshes with the snap-fit ​​end teeth. When the spokes and rim are assembled, the snap-fit ​​end teeth embed into the reverse-locking structure, forming a tight concave-convex fit. This fit not only achieves axial positioning between the spokes and rim, preventing them from separating under axial force, but also effectively restricts relative circumferential rotation, thereby transmitting the torque required to drive the hub's rotation. Furthermore, this mechanical interlocking structure also plays a role in automatic alignment during subsequent inertial friction welding: before welding, the initial meshing of the end teeth automatically aligns the axes of the spokes and rim, ensuring uniform circumferential pressure distribution at the welding interface, thus obtaining a metallurgical bonding layer with consistent thickness and few defects. It can be said that the mechanical interlocking structure is both a load-bearing component and part of the welding fixture, which greatly simplifies the alignment process before welding.

[0031] As one specific implementation method, a continuous bonding layer is formed by solid-state welding to metallurgically bond the spokes and the rim; the solid-state welding is inertial friction welding or friction stir welding.

[0032] In this embodiment, a continuous bonding layer is formed at the connection interface using a solid-state welding process. This continuous bonding layer allows the materials of the spokes and rim to diffuse into each other at the atomic scale, forming a strong metallic bond. Its strength can reach most of the strength of the weaker base material, thereby ensuring that the load is effectively transferred between the two, and the connection reliability is close to or even exceeds that of an integral cast structure.

[0033] Solid-state welding can be performed using inertial friction welding. Inertial friction welding utilizes the principle of converting rotational kinetic energy into heat energy, causing the contact interface to rapidly heat to a thermoplastic state under pressure. Subsequent upsetting causes plastic flow in the material, extruding oxide films and impurities, forming a pure metallurgical bond. This method has extremely short welding time, a narrow heat-affected zone, and high production efficiency, making it very suitable for mass production of rotating structures.

[0034] Another preferred solid-state welding method is friction stir welding. For the connection of this rotating structure in this embodiment, specialized friction stir welding equipment can be used. Friction stir welding has significant advantages such as low heat input, narrow heat-affected zone, and minimal workpiece deformation. Furthermore, it does not require high-speed workpiece rotation during welding, thus reducing the requirements for clamping accuracy. The weld microstructure after friction stir welding is a fine forging structure, and its mechanical properties can reach over 90% of the base material, making it particularly suitable for wheel products with high dimensional accuracy requirements. In addition, friction stir welding does not produce liquid spatter, resulting in a clean welding environment, and it eliminates the need for welding wire or shielding gas, further reducing manufacturing costs.

[0035] In addition to the two main methods mentioned above, this embodiment can also employ other solid-state welding or solid-like welding techniques depending on specific needs. For example, ultrasonic-assisted diffusion welding can be used, applying ultrasonic vibration to the connection interface, supplemented by relatively low temperature and pressure, to induce atomic diffusion bonding at the interface. This method avoids softening of the base material caused by high temperatures and is particularly suitable for rims that have already been heat-treated for strengthening, but the welding time is relatively long. Another example is capacitor discharge welding, which can be used for small rims or non-load-bearing decorative rims. This method uses a large instantaneous current to melt the contact micro-areas and complete the connection under upsetting. The equipment is simple and fast, but quality control is difficult, and it is not recommended for safety components. For non-circular cross-sections or irregularly shaped spokes, linear friction welding can also be used, where the workpiece generates heat through friction under high-frequency reciprocating vibration and is upsetting to join, suitable for rims with special shapes.

[0036] In one specific implementation, the spokes and rim are formed into an integral component by low-pressure casting and heat treatment.

[0037] The wheel rim is formed into a single component through low-pressure casting and heat treatment. Low-pressure casting allows molten metal to fill the mold smoothly under pressure, significantly reducing porosity and shrinkage defects, resulting in high-density castings with superior mechanical properties compared to conventional gravity casting. Subsequent heat treatment further improves the mechanical properties of the cast aluminum alloy, significantly enhancing its yield strength and hardness while maintaining good toughness.

[0038] The spokes can be manufactured using various processes. For aluminum-magnesium alloys, they can be formed by precision forging or CNC milling. Aluminum-magnesium alloys have good deformability and machinability. Forging can produce continuous metal flow lines, further improving fatigue strength; high-speed milling can produce complex curved shapes and hollow structures, achieving lightweighting.

[0039] As one specific implementation method, the aluminum-magnesium alloy material is from the 5000 series, specifically one of the alloys 5083, 5A05, or 5B06; the cast aluminum alloy material is an aluminum-silicon cast aluminum alloy.

[0040] The spoke material is primarily made of aluminum-magnesium alloy, specifically 5000 series aluminum alloys with high fatigue strength. For example, 5A05 or 5B06 alloys with higher magnesium content are suitable for hubs subjected to extreme loads. In specific applications requiring even higher strength, a combination of 6-series forged aluminum (such as 6061 aluminum alloy) and 5000 series aluminum-magnesium alloy can be used. In this case, the main body of the spoke remains a 5000 series alloy, but 6-series materials are embedded or reinforced in localized high-stress areas. 6-series aluminum alloys can achieve higher yield strength through aging treatment while maintaining good corrosion resistance.

[0041] Wheel rim materials are strictly limited to cast aluminum alloys, with A356.2 being the preferred choice due to its excellent casting properties, good mechanical properties, and proven mass production experience. In applications with slightly lower performance requirements, A356.0 or other cast aluminum-silicon alloys with similar compositions, such as A357, can be used as substitutes. A357 contains trace amounts of beryllium, which reduces the tendency for melt oxidation and improves the density of the casting, making it suitable for high-end vehicles. Furthermore, for certain special requirements, such as heavy-duty vehicles with high high-temperature strength requirements, aluminum-silicon-copper cast alloys can be considered; however, it should be noted that the reduced corrosion resistance must be compensated for with additional coatings.

[0042] This embodiment uses a high-performance aluminum-magnesium alloy, such as alloy 5083, in the spoke section, which bears the most complex alternating stress. Its tensile strength is ≥270MPa, yield strength is ≥125MPa, and its fatigue performance is significantly better than that of traditional low-pressure cast A356 aluminum alloy. In the rim section, which has a complex shape and is primarily for pressure bearing and heat dissipation, the mature and low-cost low-pressure cast A356 aluminum alloy is used. Therefore, the overall fatigue strength and rigidity of the wheel hub approach the level of forged wheel hubs, while the manufacturing cost is far lower than that of fully forged wheel hubs, achieving a technical and economic effect of 1+1>2.

[0043] Optionally, after friction welding, a layer of high-strength epoxy resin structural adhesive can be applied to the back (non-primary load-bearing surface) where the spokes and rim meet. This epoxy resin structural adhesive layer can not only further eliminate micro gaps and prevent the intrusion of corrosive media, but also provide additional damping and vibration reduction effects, absorb high-frequency micro-vibration energy, share some shear loads, and improve safety redundancy.

[0044] Optionally, due to the potential difference between the aluminum-magnesium alloy (spokes) and the A356 aluminum alloy (rim), galvanic corrosion may occur in humid environments. Therefore, one of the following surface treatments can be applied to the connection interface (especially the mechanically interlocking tooth surfaces) before welding: Micro-arc oxidation: A dense alumina ceramic film (10-30 μm thick) is generated on the surface of the spoke teeth, which is electrically insulating and wear-resistant.

[0045] Electroless nickel plating: Chemically depositing a layer of Ni-P alloy (5-10 μm thick) on the surface of the end teeth can significantly reduce the galvanic current, but the uniformity of the plating layer needs to be controlled.

[0046] Apply a conductive and anti-corrosion primer: such as a conductive paint containing zinc chromate, which is both conductive and anti-corrosion, and does not affect the heat generated by friction welding.

[0047] In this embodiment, high-performance aluminum-magnesium alloy is used in the spokes, which bear the most complex stress, to ensure high fatigue strength and high rigidity of the wheel hub as a whole, with performance indicators approaching those of forged wheel hubs. In the rim, which has a complex shape and is mainly for bearing pressure and heat dissipation, low-pressure cast aluminum alloy, which is technically mature and inexpensive, is used to give full play to its advantages of good casting performance and high cost performance. The spokes and rim adopt a composite connection method that combines mechanical interlocking and welding. The mechanical interlocking structure provides strong anti-torsional capacity and precise alignment, avoiding interface fretting wear.

[0048] The core of this embodiment lies in the combined use of mechanical interlocking and solid-state welding, rather than relying solely on one connection method. The mechanical interlocking structure mainly performs the following functions: achieving rapid and precise axial and circumferential positioning before welding; providing uniform contact pressure during welding to assist in forming a high-quality weld; and serving as the primary torque transmission path during post-weld service, sharing the shear load of the weld interface to prevent weld failure due to overload. The metallurgical bonding layer formed by solid-state welding mainly performs the following functions: achieving material continuity at the microscopic level, making the spokes and rim mechanically as a single unit; providing a sealing effect to prevent corrosive media from penetrating the interface; and absorbing the energy for fretting wear and fatigue crack initiation under complex alternating loads through the toughness of atomic bonds.

[0049] The synergistic effect of both methods results in a comprehensive mechanical performance at the connection interface that far surpasses that of a single connection method. For example, with only mechanical interlocking and no welding, fretting wear leads to gradual loosening of the contact surface and a decrease in connection stiffness; with only welding and no mechanical interlocking, if a local crack appears in the weld under extreme conditions, the crack may rapidly propagate to the entire interface. However, with the combination of both, the mechanical interlocking provides a physical barrier to crack propagation, while welding provides a continuous medium free from fretting, thus achieving double protection.

[0050] In actual production, the machining accuracy of the mechanical interlocking structure directly affects welding quality and assembly efficiency. The machining of the end teeth typically employs high-precision CNC lathes or specialized gear grinding equipment to ensure consistency in parameters such as tooth pitch, tooth profile angle, and tooth height. After machining, random inspection can be performed using optical projection or coordinate measuring machine (CMM). Pre-welding cleaning is crucial, requiring thorough removal of oil and oxide films to avoid welding defects. For friction stir welding, strict control of the stirring head wear and the treatment of the exit hole is also necessary.

[0051] After welding, localized stress-relieving annealing can be performed on the weld area as needed to eliminate residual stress. Subsequently, fluorescent penetrant testing or ultrasonic scanning is conducted to ensure the absence of defects such as cracks and lack of fusion. For products with higher requirements, post-treatment methods such as laser shock annealing can be used to introduce residual compressive stress into the heat-affected zone, further improving fatigue life.

[0052] Example 2 The purpose of this embodiment is to provide a method for processing hybrid material wheel hubs, including: The spokes are independently manufactured from aluminum-magnesium alloy, and the first mechanical interlocking structure is machined on the spoke connection end face; The wheel rim is independently manufactured from cast aluminum alloy material, and a second mechanical interlocking structure that matches the first mechanical interlocking structure is machined on the connecting end face of the wheel rim. The spokes and the rim are positioned and pre-assembled using the first mechanical interlocking structure and the second mechanical interlocking structure; The pre-assembled wheel spokes are welded to the wheel rim to form a continuous bonding layer.

[0053] In one implementation, aluminum-magnesium alloy sheet or forging blank is CNC milled or forged to form the spoke body and the first mechanical interlocking structure; a rim blank is formed using a low-pressure casting process, followed by heat treatment; and finally, the rim connecting end face is machined to form the second mechanical interlocking structure. As one implementation method, the pre-assembled wheel spokes and wheel rim are welded together by solid-state welding process to form a continuous bonding layer; solid-state welding is inertial friction welding or friction stir welding.

[0054] As one implementation, after the solid-state welding step, the welded area is further subjected to stress-relief annealing.

[0055] In this embodiment, taking the manufacture of an 18-inch hybrid material wheel for an urban SUV as an example, the specific steps of a hybrid material wheel processing method according to this embodiment are described: Step 1: Component design and material preparation stage.

[0056] Step 11: Before manufacturing begins, a precise digital design must be completed. A detailed digital model of the wheel hub is created using three-dimensional computer-aided design software, clearly distinguishing between the spokes and the rim.

[0057] Wheel spoke design: It adopts a double-piece hollow design with five pairs of spokes, which maximizes weight reduction while ensuring space for installing brake discs and calipers.

[0058] The wheel spokes under simulated working conditions were analyzed using finite element analysis software (such as Abaqus or ANSYS), including bending fatigue testing, radial fatigue testing, and impact testing. Based on the mechanical property data of aluminum-magnesium alloy 5083, structural reinforcement was applied to high-stress areas such as the connection between the spokes and the center disc, and the transition between the spokes and the connection interface. Topology optimization was performed on low-stress areas to remove excess material. The final determined minimum wall thickness of the wheel spokes was 4.5 mm, significantly lower than the 6-7 mm of traditional cast wheel spokes, achieving effective weight reduction.

[0059] Wheel rim design: The wheel rim structure conforms to the J / T standard, and its bead seat angle, hump height, peak line position, etc. are all designed according to the standard.

[0060] The key is the precise design of the interface connecting the spokes and the wheel. In this embodiment, a coupling end-tooth structure is used as the mechanical interlocking structure. The coupling end-tooth structure was chosen because it has extremely high torsional stiffness and precise circumferential positioning capability. The end-tooth parameters are: 72 teeth, tooth profile angle 60°, and tooth height 3.5mm. This design ensures that the spokes and rim can automatically align during friction welding and can jointly withstand huge torsional loads after welding.

[0061] Step 12: Raw material preparation and inspection.

[0062] Wheel spoke blanks: 5083-H112 temper aluminum-magnesium alloy rolled discs conforming to GB / T3880 standard. Their specific chemical composition needs to be confirmed by spectrometer testing: Mg content 4.5%, Mn content 0.7%, Cr content 0.15%, Fe and Si impurities both below 0.4%, balance Al.

[0063] Mechanical performance requirements: tensile strength ≥270MPa, yield strength ≥125MPa, elongation ≥12%. Before the billet is put into storage, ultrasonic testing is required to ensure that there are no internal defects such as cracks or delamination.

[0064] Wheel rim blank: A356.2 aluminum alloy ingots are used for low-pressure casting. The chemical composition of the aluminum ingots must meet the following requirements: Si 6.5-7.5%, Mg 0.25-0.45%, Ti 0.08-0.20%, Fe < 0.12%. The aluminum ingots are melted using a medium-frequency induction furnace, and the melt temperature is controlled at 720-750℃.

[0065] Before casting, the melt needs to be refined and modified: high-purity argon gas is introduced to remove hydrogen and oxide inclusions, and Al-Sr modifier is added to change the eutectic silicon from needle-like to fibrous, so as to greatly improve the toughness of the material.

[0066] Step 2: Independent manufacturing and processing of components.

[0067] Step 21: Precision machining of wheel spokes. The wheel spokes are manufactured using a subtractive manufacturing strategy of milling instead of forging to ensure the uniformity of material properties and the precision of the structure.

[0068] Rough machining: The 5083 aluminum-magnesium alloy disc blank is clamped on the worktable of a large vertical CNC milling machine. First, a face milling cutter is used to perform surface finishing on both sides of the blank to ensure the flatness of the reference surface. Then, a large-diameter end mill is used to quickly mill the basic outline and weight reduction groove of the back of the spoke (mounting surface) at a high feed rate, leaving a machining allowance of 2mm on each side.

[0069] Flipping and positioning: After rough machining of the back side, use a precision fixture to flip the workpiece and reposition it.

[0070] Front-side finishing: By replacing the ball end mill with a small-diameter end mill and a finishing end mill, the complex curved surface of the spoke front, the aerodynamic shape of the spokes, and the bolt hole seats are milled layer by layer according to the design procedure. This process uses high-speed cutting technology, with the spindle speed reaching 12,000 rpm and the feed rate precisely controlled to obtain excellent surface roughness (Ra<1.6μm).

[0071] Interface machining: The semi-finished product is transferred to a high-precision CNC lathe, and the end teeth of the outer edge of the wheel spoke are precision machined using PVD-coated carbide tools at a low feed rate. The accuracy of the tooth profile is crucial to ensuring the subsequent welding quality. After machining, an optical projector is used to perform 100% inspection of the tooth pitch, tooth profile angle, and tooth height of the end teeth, and the tolerance must be controlled within ±0.1mm.

[0072] After all machining is completed, the spokes are subjected to vibration aging treatment to eliminate internal residual stress caused by cutting; finally, the spokes are ultrasonically cleaned with alkaline cleaning agent and deionized water to thoroughly remove cutting fluid and metal chips, and then dried with compressed air.

[0073] Step 22: Low-pressure casting and heat treatment of the wheel rim.

[0074] Step 221: Mold preparation and low-pressure casting: Close the metal mold preheated to about 350°C, spray the mold cavity surface with boron nitride-based release agent and heat insulation coating; transfer the refined A356.2 aluminum liquid into a heat-insulating crucible, seal it and introduce dry compressed air.

[0075] The pressure profile is precisely programmed: first, molten aluminum is smoothly raised to fill the runner at a low pressure (approximately 0.2 bar), then the pressure is increased to 0.6-0.8 bar within 2-3 seconds, allowing the molten aluminum to smoothly fill the mold under pressure, and then solidified at this pressure for approximately 3 minutes. This process effectively reduces porosity and shrinkage, resulting in dense castings.

[0076] Step 222: Blank Cleaning: Remove the casting from the mold and use a robotic saw to cut off the gating system and risers. Then, use a shot blasting machine to clean the rim surface with 0.3mm diameter steel shot to remove oxide scale and burrs.

[0077] Step 223: T6 heat treatment: This is a key step to improve the mechanical properties of the A356.2 wheel rim, and its process curve must be strictly controlled.

[0078] Solution treatment: The wheel rim is placed in a box-type resistance furnace and heated to 535±5℃, and held at this temperature for 8 hours. The purpose is to allow the strengthening phase Mg2Si to fully dissolve into the aluminum matrix, forming a supersaturated solid solution.

[0079] Rapid quenching: After the heat treatment is completed, quickly transfer the rim to a hot water bath at 60-80℃ for quenching. The transfer time should be less than 15 seconds. The purpose of rapid cooling is to "freeze" the supersaturated solid solution at room temperature, preparing it for subsequent aging precipitation. Temperature control is crucial; too low a temperature can easily lead to deformation and cracking, while too high a temperature will cause the strengthening phase to precipitate prematurely, reducing the strengthening effect.

[0080] Artificial aging: The quenched wheel rim is placed in an aging furnace and held at 155±5℃ for 4 hours. This process causes the strengthening phase to precipitate in a dispersed and fine form in the supersaturated solid solution, thereby significantly improving the strength (especially the yield strength) and hardness of the wheel rim.

[0081] Step 224: Machining: After heat treatment, the rim is machined. First, using the rim's center hole for positioning, the bead seat and rim flange are precision machined to ensure their roundness and dimensional accuracy, meeting tire installation and airtightness requirements. Then, on the inner base of the rim, using the same equipment and standards as for machining the spoke end teeth, fully meshing mating end teeth are precision machined. Step 3: Composite connection assembly stage.

[0082] Step 31: Pre-welding preparation and alignment.

[0083] It adopts a large-tonnage professional inertial friction welding machine, which has a high-precision spindle rotation system, hydraulic servo pressurization system and computer control system.

[0084] The machined spokes are clamped on the hydraulic fixture at the spindle end, ensuring that the radial runout is less than 0.05mm. The rim is then clamped on the fixture at the movable slide end.

[0085] Start the laser alignment system of the equipment, fine-tune the position of the slide table to ensure that the alignment error between the spokes and the rim axis is less than 0.1mm; at the same time, manually rotate the spindle to make the end teeth of the two initially mesh, preparing for welding.

[0086] Step 32: The welding parameters for the inertial friction welding process are determined through optimization during preliminary process experiments and are precisely executed by the computer system. Step 321: Start the spindle motor to drive the spokes to rotate faster. When the spindle speed reaches the preset 2850 rpm, the system stores 185 kJ of kinetic energy. At this time, the spindle is disengaged from the drive motor.

[0087] Step 322: Move the sliding table at high speed to bring the spokes into contact with the end teeth of the rim and apply an initial frictional pressure of 15 MPa instantly. At the moment of contact, the huge frictional force does work, converting mechanical energy into heat energy, causing the metal at the contact interface to heat up to about 450-480°C in a very short time (about 1-2 seconds), which is below its solidus line, but in a thermoplastic state.

[0088] Step 323: In the thermoplastic state, the computer-controlled forging pressure is rapidly increased to 50 MPa. Under this high pressure, the ductile metal at the tip of the end teeth undergoes intense plastic flow, and the oxide film and impurities at the interface are completely broken up and extruded from the bonding surface, forming annular flash. Simultaneously, the atoms of the pure aluminum-magnesium alloy and A356 aluminum alloy on both sides diffuse into each other under high temperature and pressure, and grains grow across the interface, forming a strong metallurgical bonding layer. The entire welding process lasts approximately 5-7 seconds.

[0089] Step 324: After the spokes have completely stopped rotating, the hydraulic system continues to maintain the upsetting pressure for about 3-5 seconds, so that the weld can complete dynamic recrystallization and cooling under pressure, forming a fine equiaxed crystal structure, thereby obtaining the best mechanical properties.

[0090] Step 33: Post-weld treatment.

[0091] Step 331: After welding, the assembly is transferred to a CNC lathe and diamond tools are used to completely remove the flash formed on the inner and outer diameters of the joint, so that the weld area has a smooth and flat appearance and avoids stress concentration.

[0092] Step 332: Place the wheel assembly into a heat treatment furnace for localized stress-relieving annealing. The furnace temperature is controlled at 250℃, and the assembly is held at this temperature for 2 hours before cooling in the furnace. This process aims to eliminate residual stress in the weld heat-affected zone without compromising the mechanical properties of the wheel spokes and rim body.

[0093] Step 4: Final finishing and quality inspection stage.

[0094] Step 41: Finishing and dynamic balancing.

[0095] Step 411: Perform final finishing on the welded wheel assembly. Finishing includes: finishing the center hole, bolt holes, valve stem holes; finishing the decorative surface of the wheel spokes, etc.

[0096] Step 412: Detect the imbalance of the wheel hub on a dynamic balancing machine. For the detected imbalance points, a small amount of material is removed by milling at a designated location on the rim (usually on the inside) to correct the imbalance.

[0097] This embodiment requires the residual imbalance to be less than 5 g·cm, which is far higher than the industry standard, in order to ensure the stability of high-speed driving.

[0098] Step 42: Non-destructive testing and performance verification.

[0099] Step 421: Perform 100% fluorescent penetrant testing on the wheel hub, especially the weld area. After cleaning, apply penetrant and developer, and observe under ultraviolet light to ensure that there are no surface defects such as cracks or incomplete welding in the weld and heat-affected zone.

[0100] Step 423: Take samples from each production batch and conduct destructive testing on a dedicated test bench in accordance with national standards.

[0101] Radial fatigue test: Simulate road loads by applying a radial force obtained from the converted design load to the wheel hub and rotating it 1 million times.

[0102] Bending fatigue test: Simulating bending moment during cornering, alternating bending moments were applied to the wheel hub. The sample in this embodiment also far exceeded standard requirements. All failure points occurred on the spokes or rim body, while the connection interface remained intact, demonstrating the extreme reliability of this composite connection scheme.

[0103] Air tightness test: Install the wheel hub on the test bench, fill it with gas at a certain pressure and immerse it in a water tank. Hold the pressure and observe that no air bubbles are generated, to ensure that the wheel hub itself does not leak air.

[0104] Step 423: Surface Treatment. All inspected wheel hubs undergo final surface treatment according to customer requirements. For example, sandblasting is performed first, followed by multiple layers of spraying such as primer, color paint, and clear protective varnish, and then curing in an oven; or precision mechanical polishing is performed to obtain a high-gloss mirror effect.

[0105] Optionally, the spokes can be manufactured using isothermal forging to obtain better metal flow lines and mechanical properties, and then the connection interface can be precision machined.

[0106] Optionally, for the rim, a spinning process can be used to strengthen the roller groove area of ​​the rim after casting, so as to further reduce the wall thickness and reduce the weight.

[0107] The purpose of this embodiment is to provide a vehicle that uses a hybrid material wheel hub as described above, or a hybrid material wheel hub manufactured using the hybrid material wheel hub manufacturing method described above.

[0108] While the specific embodiments of the present invention have been described above in conjunction with the accompanying drawings, this is not intended to limit the scope of protection of the present invention. Those skilled in the art should understand that various modifications or variations that can be made by those skilled in the art without creative effort based on the technical solutions of the present invention are still within the scope of protection of the present invention.

Claims

1. A hybrid material wheel hub, comprising spokes and a rim, characterized in that, The spokes are made of aluminum-magnesium alloy, and the rim is made of cast aluminum alloy. A mechanical interlocking structure is provided at the connection interface between the spokes and the rim, and a continuous bonding layer is welded between the spokes and the rim.

2. The hybrid material wheel hub as described in claim 1, characterized in that, The mechanical interlocking structure is an end tooth structure or a spiral sawtooth structure that is evenly distributed along the circumference.

3. A hybrid material wheel hub as described in claim 1, characterized in that, A continuous bonding layer is formed by solid-state welding, which metallurgically bonds the spokes to the rim; the solid-state welding is inertial friction welding or friction stir welding.

4. A hybrid material wheel hub as described in claim 1, characterized in that, The spokes and rim are formed into an integral component by low-pressure casting and heat treatment.

5. A hybrid material wheel hub as described in claim 1, characterized in that, The aluminum-magnesium alloy material is a 5000 series aluminum alloy; the cast aluminum alloy material is an aluminum-silicon series cast aluminum alloy.

6. A method for processing a hybrid material wheel hub, characterized in that, include: The spokes are independently manufactured from aluminum-magnesium alloy, and the first mechanical interlocking structure is machined on the spoke connection end face; The wheel rim is independently manufactured from cast aluminum alloy material, and a second mechanical interlocking structure that matches the first mechanical interlocking structure is machined on the connecting end face of the wheel rim. The spokes and the rim are positioned and pre-assembled using the first mechanical interlocking structure and the second mechanical interlocking structure; The pre-assembled wheel spokes are welded to the wheel rim to form a continuous bonding layer.

7. The method for processing a hybrid material wheel hub as described in claim 6, characterized in that, Aluminum-magnesium alloy plates or forging blanks are CNC milled or forged to form the spoke body and the first mechanical interlocking structure; the rim blank is formed by low-pressure casting process, then the rim blank is heat treated, and finally the rim connecting end face is machined to form the second mechanical interlocking structure.

8. A method for processing a hybrid material wheel hub as described in claim 6, characterized in that, The pre-assembled wheel spokes and rim are welded together by solid-state welding process to form a continuous bonding layer; the solid-state welding is inertial friction welding or friction stir welding.

9. A method for processing a hybrid material wheel hub as described in claim 8, characterized in that, Following the solid-state welding step, the welded area is further subjected to stress-relief annealing.

10. A vehicle, characterized in that, A hybrid material wheel hub manufactured using a hybrid material wheel hub as described in any one of claims 1-5, or a hybrid material wheel hub manufacturing method as described in any one of claims 6-9.

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