Preparation process of efficient-cooling high-crack-resistance automobile hub lost foam casting

Abstract

The invention relates to the technical field of automobile hub die casting preparation, and provides an efficient-cooling high-crack-resistance automobile hub evanescent mode casting preparation process which comprises the following steps: step 1, bead pretreatment: EPS beads are pre-foamed in a pre-foaming device with the pressure of 0.04-0.05 MPa at the preheating temperature of 82-84 DEG C; step 2, forming a white mold, wherein a mold gap is kept to be 3.5-4.5 mm during mold closing; 3, gradient type white mold drying is conducted, specifically, drying is conducted for 6 hours under the conditions that the temperature is 38-42 DEG C and the humidity is 25-35% in the first stage, and drying is conducted for 10 hours under the conditions that the temperature is 43-47 DEG C and the humidity is 15-25% in the second stage; step 4, coating a composite coating; 5, preparing a sand mold; step 6, smelting and pouring; step 7, efficient cooling; and 8, post-treatment, including coating layer stripping, surface cleaning and stress elimination. Through collaborative optimization of whole-process technological parameters, the anti-cracking performance of the automobile hub lost foam casting is remarkably improved, and the problem of hot cracks caused by uneven cooling and insufficient coating performance in a traditional process is effectively solved.

Description

Technical Field

[0001] This invention relates to the field of automotive wheel hub mold casting technology, specifically to a high-efficiency cooling process for preparing high-crack-resistant automotive wheel hub lost foam castings. Background Technology

[0002] As a core component of the vehicle's driving system, the performance of automotive wheels directly affects the vehicle's driving safety and stability. With the automotive industry's trend towards lightweight and high-strength designs, higher demands are being placed on the mechanical properties, fatigue resistance, and manufacturing precision of wheels. Lost foam casting technology, due to its advantages such as near-net-shape forming, simplified processes, and lower costs, has been widely used in automotive wheel production, becoming an important technological means to achieve efficient and precise wheel manufacturing.

[0003] The existing lost foam casting process for manufacturing automobile wheels still has many technical shortcomings. On the one hand, the cooling process often uses a single cooling method, which makes it difficult to balance cooling efficiency and temperature uniformity. This leads to thermal stress in different parts of the wheel hub due to excessive temperature differences, especially in the stress concentration area where the spokes and rim connect, which is prone to thermal cracking. On the other hand, the coating performance is not well adapted to the process. Single-formulation coatings are prone to peeling or poor permeability under the scouring of high-temperature molten metal, resulting in porosity defects. At the same time, the lack of coordinated control of parameters in the bead pretreatment and sand mold preparation processes leads to white mold deformation and uneven casting structure, which further affects the crack resistance and mechanical stability of the wheel hub. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides a highly efficient cooling process for preparing lost foam castings of automotive wheel hubs with high crack resistance, solving the problems of limited cooling methods and insufficient compatibility between coating performance and process.

[0005] To achieve the above objectives, the present invention provides a process for preparing high-crack-resistant lost foam castings for automotive wheel hubs with efficient cooling, comprising the following steps: Step 1: Bead pretreatment. The EPS beads are pre-foamed in a pre-foaming device with a pressure of 0.04-0.05MPa and a preheating temperature of 82-84℃. After foaming, the bead density is controlled at 23-26g / L. The curing time is adjusted according to the ambient temperature, which is 5-7 hours in summer and 9-11 hours in winter. Step 2: White mold forming. A dual-cavity linkage forming equipment is used. When the mold is closed, the mold gap is maintained at 3.5-4.5mm. The clamping pressure is set at 160-180bar. After the mold is preheated to 88-92℃, the beads are solidified by penetrating heating. The pressure holding time is 3-4s, and the vacuum delay is 85-95s. Step 3: Gradient drying of white mold. The first stage is drying at 38-42℃ and 25-35% humidity for 6 hours, and the second stage is drying at 43-47℃ and 15-25% humidity for 10 hours, so that the moisture content of the white mold is reduced to below 0.8%. Step 4: Apply composite coating using a three-layer coating process. The base coat has a Baume degree of 58-60, the middle coat 63-65, and the top coat 66-68. After each layer is applied, dry it at 40-45℃ for 8-12 hours. The total coating thickness is controlled at 1.2-1.8mm. Step 5: Sand mold preparation. Use a mixture of quartz sand and zircon sand in a mass ratio of 3:1. Lay the bottom sand to a height of 180-220mm and compact it with vibration twice. The first vibration frequency is 2000-2200 rpm for 40-60s, and the second vibration frequency is 2400-2800 rpm for 90-110s. Step 6: Smelting and casting. The furnace charge is composed of 60% scrap aluminum, 35% aluminum ingots, and 5% master alloy. The smelting temperature is 1550-1570℃, with 0.3-0.5% rare earth inoculant added. The casting temperature is 1470-1490℃. During casting, the negative pressure is maintained at 0.025-0.04MPa. A stepped casting speed is adopted, with an initial speed of 1.2-1.5kg / s, which is reduced to 0.8-1.0kg / s after 30s. Step 7: Efficient cooling. Within 30 seconds after pouring, start the dual-circulation cooling system. First stage: water mist cooling for the first 5 minutes at a cooling rate of 8-10℃ / s. Second stage: air mist cooling for 5-15 minutes at a cooling rate of 3-5℃ / s. Third stage: natural cooling for 15-30 minutes, so that the casting temperature drops from the pouring temperature to below 200℃. Step 8, post-treatment, including coating peeling, surface cleaning and stress relief. Stress relief is carried out by holding at 200-250℃ for 2-3 hours and then cooling with the furnace.

[0006] Preferably, the pre-foaming device in step one is equipped with a temperature compensation unit. When the real-time temperature deviates from the set value by more than ±1℃, the steam supply is automatically adjusted. The adjustment formula is as follows:

[0007] in This is a proportionality constant, with a value ranging from 0.8 to 1.2. This represents the temperature deviation value.

[0008] Preferably, the dual-cavity linkage molding equipment in step two includes a synchronous control unit to ensure that the heating time and holding pressure deviation of the two cavities do not exceed ±0.5s and ±5bar, respectively.

[0009] Preferably, in step three, the gradient white mold drying adopts a humidity feedback adjustment unit. When the humidity difference between the surface layer and the core of the white mold is detected to exceed 5%, the second stage drying time is automatically extended by 1-2 hours.

[0010] Preferably, the composite coating in step four consists of a base layer, a middle layer, and a top layer. The weight ratio of the base layer components is 40% magnesia powder, 5% silica sol, and 0.5% suspending agent. The weight ratio of the middle layer components is 35% pearlescent powder, 3% white latex, and 0.3% dispersant. The weight ratio of the top layer components is 25% mica powder, 1.5% flame retardant, and 0.2% leveling agent.

[0011] Preferably, the rare earth inoculant in step six is ​​a lanthanum-cerium alloy, wherein the lanthanum content is 25-30%, the cerium content is 60-65%, and the remainder is unavoidable impurities. It is added in a flow-inoculated manner, continuously added according to a set ratio through a spiral conveying unit.

[0012] Preferably, the dual-cycle cooling system in step seven includes a temperature sensing unit with six temperature sensors evenly arranged along the radial direction of the hub to monitor the temperature gradient of the casting in real time. When the local temperature difference exceeds 20°C, directional cooling compensation is activated.

[0013] Preferably, in step eight, stress relief adopts a stepped heating mode, taking 30 minutes to heat from room temperature to 100°C, 60 minutes to heat from 100 to 200°C, and 30 minutes to heat from 200 to 250°C. After the heat preservation is completed, the temperature is reduced to room temperature at a rate of 5°C / min.

[0014] Preferably, in step five, the particle size distribution of the molding sand is as follows: 30% of the particles are 0.1-0.2mm, 50% are 0.2-0.3mm, and 20% are 0.3-0.4mm. The sand is then screened and graded using an airflow classification unit.

[0015] Preferably, it also includes a quality inspection step, employing a combination of ultrasonic flaw detection and mechanical property testing, with an ultrasonic frequency of 2.5-5MHz and a detection sensitivity ≥ 2mm flat-bottom hole, mechanical properties required: tensile strength ≥320MPa, elongation ≥8%, impact toughness ≥25J / cm 2 .

[0016] This invention provides a highly efficient cooling process for manufacturing high-crack-resistant lost foam castings of automotive wheel hubs. It offers the following advantages: 1. This invention significantly improves the crack resistance of lost foam castings for automotive wheel hubs through synergistic optimization of process parameters throughout the entire process. From precise control of bead pretreatment to gradient drying to ensure the stability of the white mold, and functional adaptation of the three-layer composite coating, combined with real-time temperature gradient control by a dual-circulation cooling system, the invention effectively avoids the hot cracking problems caused by uneven cooling and insufficient coating performance in traditional processes. At the same time, the addition of rare earth inoculants and the combination of stepped casting refine the casting grains, further enhancing the stability and mechanical properties of the overall wheel hub structure.

[0017] 2. This invention improves production efficiency while ensuring the stability of casting quality. The application of dual-cavity linkage molding and automated units shortens the production cycle and reduces human error; the graded vibration and optimized sand ratio in sand mold preparation improve the compactness and permeability of the sand mold; and the stepped stress relief process in post-treatment reduces residual internal stress in the castings. These improvements significantly increase the casting yield, and the process is easy to standardize and promote, making it suitable for large-scale production needs. Attached Figure Description

[0018] Figure 1 This is a process flow diagram of the present invention. Detailed Implementation

[0019] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0020] Example 1: Please see the appendix Figure 1 This invention provides a process for preparing high-crack-resistant, efficiently cooled lost foam castings for automotive wheel hubs, comprising the following steps: Step 1: Bead Pretreatment. EPS beads are pre-foamed in a pre-foaming device at 0.04 MPa pressure and a preheating temperature of 82℃. The density of the foamed beads is controlled at 23 g / L. The curing time is adjusted according to the ambient temperature: 5 hours in summer and 9 hours in winter. The pre-foaming device is equipped with a temperature compensation unit. When the real-time temperature deviates from the set value by more than ±1℃, the steam supply is automatically adjusted. The adjustment formula is: Adjust the steam supply.

[0021] Step 2: White mold forming. A dual-cavity linkage forming equipment is used. When the mold is closed, the mold gap is maintained at 3.5mm. The clamping pressure is set to 160bar. After the mold is preheated to 88℃, penetration heating is performed. The pressure holding time is 3s and the vacuum delay is 85s. The synchronous control unit ensures that the heating time deviation between the two mold cavities is ≤±0.5s and the pressure holding deviation is ≤±5bar.

[0022] Step 3: Gradient drying of the white mold. The first stage involves drying at 38℃ and 25% humidity for 6 hours, and the second stage involves drying at 43℃ and 15% humidity for 10 hours, reducing the moisture content of the white mold to 0.7%. The humidity feedback adjustment unit detected a humidity difference of 4% between the surface and the core, eliminating the need to extend the drying time.

[0023] Step 4: Apply the composite coating using a three-layer coating process. The base coat has a Baume degree of 58 and is formulated with 40% magnesia powder, 5% silica sol, and 0.5% suspending agent. The middle coat has a Baume degree of 63 and is formulated with 35% pearlescent powder, 3% white glue, and 0.3% dispersant. The top coat has a Baume degree of 66 and is formulated with 25% mica powder, 1.5% flame retardant, and 0.2% leveling agent. After each layer is applied, it is dried at 40℃ for 8 hours, resulting in a total coating thickness of 1.2 mm.

[0024] Step 5: Sand mold preparation. A 3:1 mixture of quartz sand and zircon sand is used as molding sand. A 180mm layer of bottom sand is laid. The first vibration is performed at 2000 rpm for 40 seconds, followed by a second vibration at 2400 rpm for 90 seconds. The molding sand particle size distribution is: 30% 0.1-0.2mm, 50% 0.2-0.3mm, and 20% 0.3-0.4mm. The sand is then screened using an airflow classification unit.

[0025] Step Six: Melting and Casting. The furnace charge is composed of 60% scrap aluminum, 35% aluminum ingots, and 5% master alloy. The melting temperature is 1550℃. 0.3% of lanthanum-cerium alloy (25% lanthanum, 60% cerium) is added continuously via a screw conveyor during inoculation. The casting temperature is 1470℃, the negative pressure is 0.025MPa, the initial casting speed is 1.2kg / s, and it is reduced to 0.8kg / s after 30s.

[0026] Step 7: Efficient cooling. Within 30 seconds of pouring, the dual-circulation cooling system is activated. The first 5 minutes are water mist cooling (rate 8℃ / s), followed by 5-15 minutes of air mist cooling (rate 3℃ / s), and 15-30 minutes of natural cooling, reducing the casting temperature to 190℃. Six temperature sensors detected a local temperature difference of 18℃ (not exceeding the threshold), requiring no directional compensation.

[0027] Step 8: Post-treatment, peel off the coating layer and clean the surface. Stress relief is achieved by step heating: room temperature to 100℃ (30 min) → 100-200℃ (60 min) → 200-250℃ (30 min), hold for 2 hours and then cool to room temperature at 5℃ / min.

[0028] Quality inspection: Ultrasonic testing frequency 2.5MHz, sensitivity ≥ Φ2mm flat-bottomed hole; Mechanical property testing showed tensile strength 325MPa, elongation 8.2%, and impact toughness 25.5J / cm². 2 All of them meet the requirements.

[0029] Example 2: Step 1: Bead Pretreatment. EPS beads are pre-foamed in a pre-foaming device at 0.05 MPa pressure and a preheating temperature of 84℃. The bead density after foaming is controlled at 26 g / L. The curing time is 9 hours in winter. When the real-time temperature deviates from the set value by more than ±1℃, the steam supply is automatically adjusted using the following formula: Adjust the steam supply.

[0030] Step 2: White mold forming. A dual-cavity linkage forming equipment is used. When the mold is closed, the mold gap is maintained at 3.4mm. The clamping pressure is set to 180bar. After the mold is preheated to 92℃, penetration heating is performed. The pressure holding time is 4s and the vacuum delay is 95s. The synchronous control unit ensures that the heating time deviation between the two mold cavities is ≤±0.5s and that the parameter deviation meets the limit value.

[0031] Step 3: Gradient drying of the white mold. The first stage involves drying at 42℃ and 35% humidity for 6 hours, and the second stage involves drying at 47℃ and 25% humidity for 10 hours, reducing the moisture content of the white mold to 0.6%. The humidity feedback adjustment unit detects a 6% humidity difference between the surface and the core and automatically extends the second stage of drying by 1 hour.

[0032] Step 4: Apply the composite coating using a three-layer coating process. The base coat has a Baume degree of 60 and is formulated with 40% magnesia powder, 5% silica sol, and 0.5% suspending agent. The middle coat has a Baume degree of 65 and is formulated with 35% pearlescent powder, 3% white glue, and 0.3% dispersant. The top coat has a Baume degree of 68 and is formulated with 25% mica powder, 1.5% flame retardant, and 0.2% leveling agent. After each layer is applied, it is dried at 45°C for 12 hours, resulting in a total coating thickness of 1.8 mm.

[0033] Step 5: Sand mold preparation. A 3:1 mixture of quartz sand and zircon sand is used as molding sand. A 200mm layer of bottom sand is laid. The first vibration is performed at 2000 rpm for 60 seconds, followed by a second vibration at 2800 rpm for 110 seconds. The molding sand particle size distribution is: 30% 0.1-0.2mm, 50% 0.2-0.3mm, and 20% 0.3-0.4mm. The sand is then screened using an airflow classification unit.

[0034] Step Six: Melting and Casting. The furnace charge is composed of 60% scrap aluminum, 35% aluminum ingots, and 5% master alloy. The melting temperature is 1570℃. 0.5% lanthanum-cerium alloy (30% lanthanum, 65% cerium) is added continuously via a screw conveyor during inoculation. The casting temperature is 1490℃, the negative pressure is 0.04MPa, the initial casting speed is 1.5kg / s, and it is reduced to 1.0kg / s after 30s.

[0035] Step 7: Efficient cooling. Within 30 seconds of pouring, activate the dual-circulation cooling system. For the first 5 minutes, the water mist cooling rate is 10℃ / s; for 5-15 minutes, the air mist cooling rate is 5℃ / s; and for 15-30 minutes, allow natural cooling. The final casting temperature is 180℃. When the local temperature difference reaches 22℃, activate directional cooling compensation.

[0036] Step 8: Post-treatment, stress relief and heat preservation for 3 hours, with step heating parameters the same as in Example 1.

[0037] Quality testing was conducted using an ultrasonic frequency of 5MHz. Mechanical properties included a tensile strength of 350MPa, elongation of 9.0%, and impact toughness of 28.0J / cm². 2 .

[0038] Example 3: Step 1: Bead Pretreatment. EPS beads are pre-foamed in a pre-foaming device at 0.045 MPa pressure and a preheating temperature of 83℃. The bead density after foaming is controlled at 24.5 g / L. The curing time is 6 hours in summer. The pre-foaming device is equipped with a temperature compensation unit. When the real-time temperature deviates from the set value by more than ±1℃, the steam supply is automatically adjusted. The adjustment formula is: Adjust the steam supply.

[0039] Step 2: White mold forming. A dual-cavity linkage forming equipment is used. When the mold is closed, the mold gap is maintained at 4.0mm. The clamping pressure is set to 170bar. After the mold is preheated to 90℃, penetration heating is performed. The pressure holding time is 3.5s and the vacuum delay is 90s.

[0040] Step 3: Gradient drying of the white mold. In the first stage, the mold is dried for 6 hours at 40℃ and 30% humidity. In the second stage, the mold is dried for 10 hours at 45℃ and 20% humidity, reducing the moisture content of the white mold to 0.75%. When the humidity difference is 5%, the drying time is extended by 1.5 hours.

[0041] Step 4: Apply the composite coating using a three-layer coating process. The base coat has a Baume degree of 59 and is formulated with 40% magnesia powder, 5% silica sol, and 0.5% suspending agent. The middle coat has a Baume degree of 64 and is formulated with 35% pearlescent powder, 3% white glue, and 0.3% dispersant. The top coat has a Baume degree of 67 and is formulated with 25% mica powder, 1.5% flame retardant, and 0.2% leveling agent. After each layer is applied, it is dried at 42℃ for 10 hours, resulting in a total coating thickness of 1.5 mm.

[0042] Step 5: Sand mold preparation. A 3:1 mixture of quartz sand and zircon sand is used as molding sand. A 200mm layer of bottom sand is laid. The first vibration frequency is 2100 rpm for 50 seconds, and the second vibration frequency is 2600 rpm for 100 seconds. The molding sand particle size is 30% 0.1-0.2mm, 50% 0.2-0.3mm, and 20% 0.3-0.4mm, and is screened using an airflow classification unit.

[0043] Step Six: Melting and Casting. The furnace charge is composed of 60% scrap aluminum, 35% aluminum ingots, and 5% master alloy. The melting temperature is 1560℃. 0.4% of lanthanum-cerium alloy (27% lanthanum, 62% cerium) is added continuously via a screw conveyor during in-flow inoculation. The casting temperature is 1480℃, the negative pressure is 0.03MPa, and the initial casting speed is 1.35kg / s, which is reduced to 0.9kg / s after 30s.

[0044] Step 7: Efficient cooling. Within 30 seconds of pouring, the dual-circulation cooling system is activated. For the first 5 minutes, the water mist cooling rate is 9℃ / s, and the air mist cooling rate is 4℃ / s. After natural cooling, the final casting temperature is 185℃. Compensation is activated when the local temperature difference reaches 20℃.

[0045] Step 8: Post-treatment, peel off the coating layer and clean the surface. Stress relief is achieved by stepwise heating: room temperature to 100℃ (30 min) → 100-200℃ (60 min) → 200-250℃ (30 min), hold for 2.5 hours and then cool to room temperature at a rate of 5℃ / min.

[0046] Quality inspection: ultrasonic testing frequency 3.5MHz, sensitivity ≥ Φ2mm flat-bottomed hole; mechanical properties: tensile strength 335MPa, elongation 8.5%, impact toughness 26.5J / cm². 2 All of them meet the requirements.

[0047] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A process for preparing high-crack-resistant lost foam castings of automotive wheel hubs with efficient cooling, characterized in that, Includes the following steps: Step 1: Bead pretreatment. The EPS beads are pre-foamed in a pre-foaming device with a pressure of 0.04-0.05MPa and a preheating temperature of 82-84℃. After foaming, the bead density is controlled at 23-26g / L. The curing time is adjusted according to the ambient temperature, which is 5-7 hours in summer and 9-11 hours in winter. Step 2: White mold forming. A dual-cavity linkage forming equipment is used. When the mold is closed, the mold gap is maintained at 3.5-4.5mm. The clamping pressure is set at 160-180bar. After the mold is preheated to 88-92℃, the beads are solidified by penetrating heating. The pressure holding time is 3-4s, and the vacuum delay is 85-95s. Step 3: Gradient drying of white mold. The first stage is drying at 38-42℃ and 25-35% humidity for 6 hours, and the second stage is drying at 43-47℃ and 15-25% humidity for 10 hours, so that the moisture content of the white mold is reduced to below 0.8%. Step 4: Apply composite coating using a three-layer coating process. The base coat has a Baume degree of 58-60, the middle coat 63-65, and the top coat 66-68. After each layer is applied, dry it at 40-45℃ for 8-12 hours. The total coating thickness is controlled at 1.2-1.8mm. Step 5: Sand mold preparation. Use a mixture of quartz sand and zircon sand in a mass ratio of 3:

1. Lay the bottom sand to a height of 180-220mm and compact it with vibration twice. The first vibration frequency is 2000-2200 rpm for 40-60s, and the second vibration frequency is 2400-2800 rpm for 90-110s. Step 6: Smelting and casting. The furnace charge is composed of 60% scrap aluminum, 35% aluminum ingots, and 5% master alloy. The smelting temperature is 1550-1570℃, with 0.3-0.5% rare earth inoculant added. The casting temperature is 1470-1490℃. During casting, the negative pressure is maintained at 0.025-0.04MPa. A stepped casting speed is adopted, with an initial speed of 1.2-1.5kg / s, which is reduced to 0.8-1.0kg / s after 30s. Step 7: Efficient cooling. Within 30 seconds after pouring, start the dual-circulation cooling system. First stage: water mist cooling for the first 5 minutes at a cooling rate of 8-10℃ / s. Second stage: air mist cooling for 5-15 minutes at a cooling rate of 3-5℃ / s. Third stage: natural cooling for 15-30 minutes, so that the casting temperature drops from the pouring temperature to below 200℃. Step 8, post-treatment, including coating peeling, surface cleaning and stress relief. Stress relief is carried out by holding at 200-250℃ for 2-3 hours and then cooling with the furnace.

2. The process for preparing a high-crack-resistant, efficiently cooled lost foam casting of an automotive wheel hub according to claim 1, characterized in that, The pre-foaming device in step one is equipped with a temperature compensation unit. When the real-time temperature deviates from the set value by more than ±1℃, the steam supply is automatically adjusted. The adjustment formula is as follows: ； in This is a proportionality constant, with a value ranging from 0.8 to 1.

2. This represents the temperature deviation value.

3. The process for preparing high-crack-resistant lost foam castings of automotive wheel hubs with efficient cooling according to claim 1, characterized in that, The dual-cavity linkage molding equipment in step two includes a synchronous control unit to ensure that the heating time and holding pressure deviation of the two cavities do not exceed ±0.5s and ±5bar, respectively.

4. The process for preparing a high-crack-resistant, efficiently cooled lost foam casting of an automotive wheel hub according to claim 1, characterized in that, In step three, the gradient white mold drying uses a humidity feedback adjustment unit. When the humidity difference between the surface and core of the white mold exceeds 5%, the second stage drying time is automatically extended by 1-2 hours.

5. The process for preparing a high-crack-resistant, efficiently cooled lost foam casting of an automotive wheel hub according to claim 1, characterized in that, In step four, the composite coating consists of a base layer, a middle layer, and a top layer. The weight ratio of the base layer components is 40% magnesia powder, 5% silica sol, and 0.5% suspending agent. The weight ratio of the middle layer components is 35% pearlescent powder, 3% white latex, and 0.3% dispersant. The weight ratio of the top layer components is 25% mica powder, 1.5% flame retardant, and 0.2% leveling agent.

6. The process for preparing a high-crack-resistant, efficiently cooled lost foam casting of an automotive wheel hub according to claim 1, characterized in that, In step six, the rare earth inoculant is a lanthanum-cerium alloy, with a lanthanum content of 25-30%, a cerium content of 60-65%, and the remainder being unavoidable impurities. It is added in a flow-inoculated manner, continuously added according to a set ratio through a spiral conveying unit.

7. The process for preparing a high-crack-resistant, efficiently cooled lost foam casting of an automotive wheel hub according to claim 1, characterized in that, The dual-cycle cooling system in step seven includes a temperature sensing unit with six temperature sensors evenly arranged along the radial direction of the hub to monitor the temperature gradient of the casting in real time. When the local temperature difference exceeds 20°C, directional cooling compensation is activated.

8. The process for preparing a high-crack-resistant, efficiently cooled lost foam casting of an automotive wheel hub according to claim 1, characterized in that, In step eight, stress relief adopts a stepped heating mode, taking 30 minutes to heat from room temperature to 100℃, 60 minutes to heat from 100 to 200℃, and 30 minutes to heat from 200 to 250℃. After the heat preservation is completed, the temperature is reduced to room temperature at a rate of 5℃ / min.

9. The process for preparing a high-crack-resistant, efficiently cooled lost foam casting of an automotive wheel hub according to claim 1, characterized in that, In step five, the particle size distribution of the molding sand is as follows: 30% of the particles are 0.1-0.2mm, 50% are 0.2-0.3mm, and 20% are 0.3-0.4mm. The sand is then screened and graded using an airflow classification unit.

10. The process for preparing a high-crack-resistant, efficiently cooled lost foam casting of an automotive wheel hub according to claim 1, characterized in that, It also includes a quality inspection step, employing a combination of ultrasonic flaw detection and mechanical property testing, with an ultrasonic frequency of 2.5-5MHz and a detection sensitivity ≥ 2mm flat-bottom hole, mechanical properties required: tensile strength ≥320MPa, elongation ≥8%, impact toughness ≥25J / cm 2 .

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