Production process of light-weight aluminum alloy EPS motor shell

Abstract

The present application relates to the technical field of motor casing, in particular to a production process of a light-weight aluminum alloy EPS motor casing, which sequentially goes through material pretreatment, gradient smelting, vacuum die casting forming, burr fine removal, shot blasting strengthening, composite heat treatment, precision milling, multi-dimensional leakage detection, micro-arc oxidation treatment, structure verification, environmental protection treatment and finished product warehousing; the process adopts composite micro-alloying, vacuum die casting, composite heat treatment and other technologies, specifically strengthens key parts, optimizes surface and size precision; at the same time, it is matched with an environmental protection treatment process, takes into account product performance and green production, solves many shortcomings of traditional processes, and adapts to the demand of new energy vehicles. The process comprehensively optimizes the comprehensive performance of the casing, takes into account light weight and high strength, improves forming precision, sealing performance and corrosion resistance; shortens the production cycle, improves the qualified rate, realizes waste recovery and waste liquid standard treatment; adapts to the demand of new energy vehicles, has advanced technology and environmental protection, and is better than the traditional process.

Description

Technical Field

[0001] This invention relates to the field of motor housing technology, specifically to a manufacturing process for a lightweight aluminum alloy EPS motor housing. Background Technology

[0002] With the rapid development of the new energy vehicle industry, the requirements for vehicle lightweighting, energy consumption control, and component reliability are continuously increasing. EPS (Electric Power Steering) is a core component affecting vehicle handling and energy consumption, and the performance of its motor housing directly determines the operational stability and service life of the EPS system. Currently, the mainstream materials for EPS motor housings are cast iron or ordinary aluminum alloy. While cast iron has high strength, its high density and weight make it difficult to meet the lightweighting requirements of new energy vehicles, easily leading to increased vehicle energy consumption. Ordinary aluminum alloys (such as the AlSi12 series) can achieve a certain degree of lightweighting, but the high content of impurities (such as Fe and Cu elements) within the material easily forms brittle phases, resulting in insufficient housing strength and fatigue resistance, and long-term use is prone to cracking and deformation.

[0003] At the production process level, existing technologies have several shortcomings. First, the smelting process often uses a single-temperature heating mode, resulting in uneven mixing of alloy components. Furthermore, the lack of targeted addition of microalloying elements makes it difficult to effectively control impurity content, leading to insufficient purity of the molten aluminum. This results in defects such as porosity and shrinkage in the subsequently die-cast housing. Second, die casting is mostly performed under atmospheric pressure, with inadequate mold cooling water system design and no special coating protection on the cavity surface. This easily leads to poor aluminum fluidity and uneven housing wall thickness after forming, increasing the risk of subsequent leaks. Third, deburring processes often rely on simple mechanical milling, which is insufficient to remove micropores and fine burrs at edges and corners. Residual burrs can easily scratch seals, causing problems during motor operation. Fourth, the heat treatment mostly adopts integral T5 treatment, which cannot strengthen key stress-bearing parts such as housing bearing mounting positions and terminal interfaces, resulting in insufficient strength of key parts, which are prone to wear or deformation after long-term vibration loads; Fifth, the surface treatment mostly adopts ordinary anodizing, and the oxide film has poor corrosion resistance, which is prone to rust in complex environments such as humidity and salt spray, shortening the service life of the housing; In addition, the existing process has a low recycling rate of die-casting waste aluminum, and the surface treatment waste liquid is directly discharged without standardized treatment, which not only wastes resources, but also does not meet the requirements of environmental protection policies and is difficult to adapt to the trend of green production.

[0004] In summary, current EPS motor housing manufacturing processes cannot fully meet the demands of new energy vehicles for lightweight, highly reliable, and long-life components in terms of material properties, molding quality, precision control, reliability, and environmental friendliness. There is an urgent need for a manufacturing process that balances lightweight, high strength, high corrosion resistance, and environmental friendliness. Summary of the Invention

[0005] (a) Technical problems to be solved

[0006] To address the shortcomings of existing technologies, this invention provides a manufacturing process for lightweight aluminum alloy EPS motor housings.

[0007] (II) Technical Solution

[0008] A lightweight aluminum alloy EPS motor housing manufacturing process includes the following steps:

[0009] S1. Material pretreatment: Lightweight aluminum alloy is selected and pre-deformed at 350℃±10℃. The reduction rate of the pre-deformation treatment is 12%-15%. After holding at the temperature for 30-40 minutes, it is naturally cooled.

[0010] S2. Gradient melting: The pretreated aluminum alloy is put into a medium-frequency induction furnace and a "low-temperature preheating-gradient heating" mode is adopted; La-Ce composite microalloying is added during the heating process;

[0011] S3. Vacuum die casting: The molten aluminum liquid is transferred to a vacuum die casting machine; the die casting machine is first evacuated to ≤50mbar, and then the aluminum liquid is injected with a feeding pressure of 35MPa. The die casting mold adopts a conformal cooling water channel, and finally a shell blank with a wall thickness difference of ≤0.8mm is obtained.

[0012] S4. Deburring: A composite process of "mechanical milling + laser deburring" is adopted; first, coarse burrs ≥0.5mm are removed by CNC milling cutter, and then fine burrs at micro-holes and corners are removed by 1064nm fiber laser.

[0013] S5. Shot blasting strengthening: A mixture of steel shot and ceramic shot is used for blasting, with a mass ratio of 3:1; the diameter of the steel shot is 0.6-0.8mm, and the diameter of the ceramic shot is 0.3-0.5mm; the blasting is carried out in two stages, with the first stage being 3 minutes of rough blasting and the second stage being 2 minutes of fine blasting.

[0014] S6. Composite heat treatment: First, perform T5 basic heat treatment at a temperature of 205℃±3℃; then, perform local induction heating on the housing bearing mounting position and terminal interface.

[0015] S7. Precision Milling: Carbide end mills are used for three-stage machining in a CNC machining center: rough milling, semi-finish milling, and finish milling. The rough milling cutting speed is 900-950 m / min, and the feed rate is 0.18-0.2 mm / r. Real-time vibration monitoring is introduced during finish milling. Dimensional compensation machining is performed on the inner holes and mounting surfaces of the machine housing.

[0016] S8. Multi-dimensional Leak Detection: First, compressed air is used to purge the inside of the casing; then, the detection is carried out at two different workstations.

[0017] S9. Micro-arc oxidation surface treatment: using a silicate-phosphate composite electrolyte, treatment is performed under pulse voltage; after treatment, an oxide film is formed with a thickness of 15-18μm; subsequently, it is immersed in a sealing agent;

[0018] S10. Structural Verification: The finished casing undergoes a combined verification of "lightweighting and strength" by testing its stress distribution through finite element simulation; the weight of the casing is also measured; and finally, the casing undergoes a full inspection of its appearance and dimensions.

[0019] S11. Environmental protection treatment: Collect waste aluminum materials generated during the die casting process, dry them at 120℃ and then remelt them; collect dust generated during the shot blasting process through a bag filter; treat the waste liquid generated from surface treatment, adjust the pH to 6.8-7.2 after neutralization and precipitation and then discharge it in compliance with standards.

[0020] S12. Finished product warehousing: Anti-static pearl cotton is used for separation and packaging, and the stacking height of each box is ≤3 layers; the storage environment temperature is controlled at 15-25℃ and the humidity is controlled at 40%-60%.

[0021] Preferably, the pre-deformation process in S1 uses a four-column hydraulic press, with the pressing rate controlled at 5-8 mm / s; forced air cooling is used during the cooling process, with a forced air speed of 2-3 m / s and an internal temperature gradient of ≤5℃ / cm.

[0022] Preferably, the "low-temperature preheating-gradient heating" mode in S2 specifically involves maintaining an initial temperature of 450℃±10℃ for 1 hour, followed by heating to 710℃±5℃ at a rate of 8-10℃ / min; the mass ratio of La to Ce in the La-Ce composite microalloy is 1:1.2; aluminum foil is used to wrap the microalloy when it is added, with a foil thickness of 0.1mm; and the rare earth residue in the alloy is ultimately controlled within the range of 0.06%-0.09%.

[0023] Preferably, the cooling water temperature in S3 is 28°C, and the surface of the mold cavity is coated with a nano-ceramic coating with a thickness of 5-8 μm. The nano-ceramic coating is an Al2O3-TiO2 composite coating with a mass ratio of Al2O3 to TiO2 of 7:3. The coating is prepared by plasma spraying.

[0024] Preferably, in S6, the local induction heating frequency is 15-20kHz, the temperature is 220℃±5℃, the aging time is 15-20min, and a ring induction coil is used, with the inner diameter of the coil being 2-3mm larger than the part to be heated; the coil moving speed is 5-6mm / s during the heating process, and the temperature of the heating zone is monitored in real time with a temperature measurement accuracy of ±2℃; the hardness uniformity error of key parts is precisely controlled to be ≤5HV.

[0025] Preferably, the "size compensation algorithm" is used during precision milling in S7; firstly, the actual machining dimensions of the first 5 machine housings are measured with a measurement accuracy of 0.001mm; the milling cutter feed rate is automatically adjusted according to the measurement results, with a feed rate compensation range of ±0.003mm.

[0026] Preferably, the two testing stations in S8 are as follows: the first station performs a water pressure test at a pressure of 0.8 bar, held for 40 seconds, with a leakage rate of <1 mL / min; the second station performs a helium mass spectrometry leak detection with a detection accuracy of 5 × 10⁻⁻⁻⁶. 9 Pa·m³ / s; Before helium mass spectrometry leak detection, the casing is placed in a drying oven at a temperature of 80℃±5℃ for 2 hours; During detection, the "negative pressure helium absorption" mode is used with a negative pressure value of -0.08MPa and a holding time of 60s.

[0027] Preferably, in step S9, the micro-arc oxidation electrolyte contains 80-90 g / L of Na2SiO3 and 30-35 g / L of Na3PO4, and NaF is added as a refining agent at a concentration of 0.5%-0.8%. After oxidation treatment, the casing is cleaned with deionized water three times for 5 minutes each time.

[0028] Preferably, the finite element simulation in S10 uses ABAQUS software. During the simulation, the casing constraint condition is set to "fixed at both ends - suspended in the middle", the vibration load is a sine wave, and the sine wave acceleration is 10g. At the same time, three finished products are sampled for physical vibration testing, with a test frequency range of 10-2000Hz. After the test, the casing is required to be free of cracks.

[0029] Preferably, the waste aluminum material in S11 needs to be magnetically separated to remove iron before smelting, and the magnetic field strength of the magnetic separation equipment is 12000-15000Gs; the surface treatment waste liquid is neutralized and then treated by a plate and frame filter press with a filter press filtration pressure of 0.6MPa.

[0030] (iii) Beneficial technical effects

[0031] Compared with existing technologies, the beneficial effects of this invention are:

[0032] 1. By combining material pretreatment with gradient melting and the addition of composite microalloys, the grain orientation of aluminum alloy is effectively improved, the formability of the material is enhanced, and the impurity content in the alloy is significantly reduced, thereby reducing the negative impact of brittleness on the strength of the casing. This gives the material both lightweight and high strength characteristics, laying a good foundation for the subsequent forming quality.

[0033] 2. Vacuum die casting, combined with conformal cooling water channels and mold nano-coating, significantly reduces defects such as porosity and shrinkage in the molten aluminum, improving the consistency of casing forming and the uniformity of wall thickness; the "mechanical milling + laser" composite deburring process can thoroughly remove burrs of different specifications, especially precisely removing micropores and fine burrs at the edges and corners, avoiding damage to seals during subsequent assembly and ensuring the sealing performance of the casing; shot blasting uses mixed shot material for segmented blasting, which not only optimizes the surface roughness of the casing, but also forms residual compressive stress on the surface, enhancing the casing's fatigue resistance.

[0034] 3. Composite heat treatment combines basic heat treatment with localized induction heating of key components to specifically enhance the strength of critical stress areas while avoiding performance waste caused by excessive strengthening of non-critical areas, ensuring precise matching of the performance of each part of the casing to the stress requirements; Multi-dimensional leak detection uses multi-station and different principle detection methods to comprehensively investigate leak risks, ensuring no coolant or oil leakage during motor operation, thus improving system reliability; Micro-arc oxidation surface treatment combined with sealing process significantly improves the corrosion resistance of the casing, making it less prone to rust in complex environments such as humidity and salt spray, extending its service life.

[0035] 4. The high recycling rate of waste aluminum in the process and the standardized treatment of shot blasting dust and surface treatment waste liquid not only reduce resource waste but also reduce the environmental impact of the production process, which meets the requirements of green production policies. At the same time, the overall process reduces rework and scrap rates through precise control of each link, improves production efficiency and product qualification rate, and combines technological advancement with economic feasibility, which can fully meet the high performance requirements of new energy vehicles for EPS motor housings. Attached Figure Description

[0036] Figure 1 This is a production process flow diagram of a lightweight aluminum alloy EPS motor housing disclosed in this invention;

[0037] Figure 2 This is a line graph comparing the overall tensile strength and overall yield strength of the embodiments and comparative examples;

[0038] Figure 3 This is a bar chart comparing the recovery rates of the examples and comparative examples with those of waste aluminum.

[0039] Figure 4 This is a radar comparison chart created by standardizing the dimensions of the performance comparison data of the examples and comparative examples. Detailed Implementation

[0040] according to Figures 1 to 4 The specific embodiments of the present invention are as follows:

[0041] Example 1

[0042] This embodiment describes a manufacturing process for a lightweight aluminum alloy EPS motor housing, with the following specific steps:

[0043] S1. Material Pretreatment: Industrial-grade AlSi9MgMn aluminum alloy ingots are selected, with the purity of the ingots controlled at 99.8%. The aluminum alloy ingots are cut into 100mm×80mm×50mm blocks using a CNC saw. The blocks are placed in a box-type heating furnace, with the furnace temperature set at 350℃ and the holding time controlled at 30 minutes. After the holding time, the blocks are transferred to a four-column hydraulic press for pre-deformation treatment. The pressing rate of the hydraulic press is set at 5mm / s, and the pre-deformation reduction rate is controlled at 12%. After the treatment, the forced air cooling system of the furnace is turned on, with the air velocity set at 2m / s, and the material is allowed to cool naturally to room temperature. During the cooling process, the internal temperature of the material is monitored in real time using thermocouples, and the internal temperature gradient of the material is controlled at ≤5℃ / cm.

[0044] S2. Gradient Melting: The pretreated aluminum alloy block is placed into a medium-frequency induction furnace. The initial temperature of the medium-frequency induction furnace is set to 450℃, and the holding time is controlled at 1 hour. During the holding period, the furnace stirring device is turned on every 15 minutes, and the stirring speed is controlled at 60 r / min to ensure uniform heating of the alloy. Then, the furnace temperature is raised to 710℃ at a rate of 8℃ / min. During the heating process, La-Ce composite microalloys are added, with the addition amount controlled at 0.08% and the mass ratio of La to Ce being 1:1.2. When adding, the microalloys are wrapped in aluminum foil with a thickness of 0.1 mm and added through the furnace feeding port. After addition, stirring is continued for 30 minutes. After stirring, the alloy composition is detected by a spectrometer. The Fe content in the alloy is ≤0.15%, the Cu content is ≤0.08%, and the rare earth residue is controlled at 0.06%.

[0045] S3. Vacuum Die Casting: The molten aluminum is transferred to a heat preservation tank, where the temperature is maintained at 700℃, and the density of the molten aluminum must be ≥2.61g / cm³. The molten aluminum is then transferred to a vacuum die casting machine. The vacuum system of the die casting machine is first activated, and the vacuum level inside the machine is evacuated to 50mbar and maintained for 5 seconds. The die casting mold is pre-installed with conformal cooling water channels. The diameter of the cooling water pipes is 8mm, and the pipe spacing is 15mm. Circulating water at 28℃ is introduced into the cooling water channels. The mold cavity surface is... An Al2O3-TiO2 composite coating was applied using plasma spraying equipment. The mass ratio of Al2O3 to TiO2 in the coating was 7:3. The spraying current was set to 380A, the spraying distance was controlled at 120mm, and the coating thickness was controlled at 5μm. The die-casting machine parameters were adjusted, with the feeding pressure set to 35MPa, the injection speed controlled at 80mm / s, the clamping force set to 4000kN, and the molding cycle controlled at 70 seconds / piece. After molding, a housing blank with a wall thickness difference ≤0.8mm was obtained.

[0046] S4. Deburring: Fix the machine housing blank on the CNC milling machine worktable; select an ER16 CNC milling cutter with a cutting diameter of 6mm, set the milling speed to 1500mm / min, and control the feed rate at 0.15mm / r to remove coarse burrs ≥0.5mm through milling; after removing the coarse burrs, transfer the machine housing to a laser deburring machine; the laser deburring machine uses a 1064nm fiber laser, sets the laser power to 15W, and controls the scanning speed at 800mm / s; use a CCD vision positioning system to lock the micro-holes ≤2mm in diameter and the fine burrs at the corners on the machine housing, and remove the fine burrs point by point, finally controlling the deburring accuracy to 0.02mm.

[0047] S5. Shot blasting strengthening: The deburred casing is placed into a tracked shot blasting machine; steel shot and ceramic shot are mixed at a mass ratio of 3:1, with steel shot diameter of 0.6mm and hardness of HRC52, and ceramic shot diameter of 0.3mm and hardness of HV1200; the shot blasting machine pressure is first set to 0.5MPa, and the shot blasting machine speed is controlled at 1200r / min for 3 minutes of rough blasting; after the rough blasting is completed, the pressure is kept constant and fine blasting is continued for 2 minutes; after shot blasting, the surface roughness of the casing is tested by a surface roughness meter, and the surface roughness reaches Ra1.2-1.6μm; then the residual compressive stress on the surface of the casing is tested by an X-ray stress meter, and the residual compressive stress is ≥120MPa.

[0048] S6. Composite Heat Treatment: The shot-blasted casing is sent to a continuous heat treatment furnace for T5 basic heat treatment; the heating rate of the heat treatment furnace is set to 10℃ / min, and the temperature is held at 205℃ for 4.5 hours; after the holding period, it is cooled to room temperature at a rate of 8℃ / min; after cooling, local induction heating is performed on the bearing mounting position and terminal interface of the casing. The diameter of the bearing mounting position hole is φ75mm, and the diameter of the terminal interface is φ12mm; the frequency of the local induction heating equipment is set to 15kHz, the heating temperature is controlled at 220℃, the coil moving speed is set to 5mm / s, and the aging time is controlled at 15 minutes; after aging treatment, the hardness of the casing is tested by a Vickers hardness tester. The hardness of the key parts reaches HV110-120, and the hardness of the non-critical parts remains at HV95-105.

[0049] S7. Precision Milling: The heat-treated machine housing is clamped in a CNC machining center; a carbide end mill with an AlCrN coating is selected, conforming to the TCMT16T304 specification; rough milling is performed first, with a cutting speed set to 900 m / min, feed rate controlled at 0.18 mm / r, and depth of cut set to 2 mm; after rough milling, semi-finish milling is performed, with a cutting speed set to 1000 m / min, feed rate controlled at 0.15 mm / r, and depth of cut set to... The milling depth is set to 0.8mm. After semi-finish milling, finish milling is performed. During finish milling, the machine tool's real-time vibration monitoring system is turned on, and the vibration sensor detection accuracy meets the requirement of amplitude ≤0.005mm. The finish milling cutting speed is set to 950m / min, the feed rate is controlled at 0.12mm / r, and the cutting depth is set to 0.3mm. After finish milling, the machine housing dimensions are checked by a coordinate measuring machine. The inner hole size reaches φ75mm±0.008mm, and the flatness of the mounting surface is controlled at ≤0.01mm / 100mm.

[0050] S8. Multi-dimensional Leak Detection: First, use compressed air to purge the inside of the casing. The compressed air pressure is set to 0.3MPa, and the purging time is controlled at 15 seconds to remove oil and debris from the inside of the casing. After purging, the casing is transferred to the water pressure testing station. After sealing the casing, 0.8 bar of compressed air is introduced, and the pressure holding time is controlled at 40 seconds. The leakage is monitored by a differential pressure sensor. After the water pressure test, the casing is transferred to the helium mass spectrometry leak detection station. A helium mass spectrometer leak detector is used for detection. The leak detector is set to a negative pressure of -0.08MPa, and the pressure holding time is controlled at 60 seconds. The leak detection accuracy reaches 5×10⁻⁻⁻⁶. 9 Pa·m³ / s.

[0051] S9. Micro-arc oxidation surface treatment: Prepare a silicate-phosphate composite electrolyte with Na2SiO3 content of 80g / L, Na3PO4 content of 30g / L, and NaF content of 0.5g / L; pour the prepared electrolyte into a micro-arc oxidation tank; place the casing as the anode and the stainless steel plate as the cathode into the micro-arc oxidation tank; set the micro-arc oxidation parameters: pulse voltage of 350V, frequency of 500Hz, duty cycle of 30%, and treatment time of 18 minutes; after treatment, remove the casing and clean it with deionized water (conductivity ≤5μS / cm), repeat the cleaning 3 times, and each cleaning time is 5 minutes; after cleaning, immerse the casing in a sealing agent with a nano-SiO2 concentration of 5% for 10 minutes; after immersion, allow it to air dry naturally.

[0052] S10. Structural Verification: A 3D model of the casing was created using ABAQUS 2022 software. The casing constraints were set to "fixed at both ends - suspended in the middle" in the software. A high-temperature load of 150℃ and a vibration load of 1500rpm were applied. The vibration load was a sine wave with an acceleration of 10g to simulate the stress distribution of the casing. At the same time, three finished casings were sampled and placed on a vibration test bench for physical vibration testing. The test frequency range was 10-2000Hz. After the test, the casing was checked for cracks and deformation. The appearance of the casing was then inspected using a colorimeter. The casing was free of scratches and the color difference ΔE ≤ 0.8. After all dimensions passed the inspection, the casing was packaged.

[0053] S11. Environmental Protection Treatment: Collect waste aluminum generated during the die casting process, place the waste aluminum in a drying oven, set the drying oven temperature to 120℃, and control the drying time to 2 hours; after drying, put the waste aluminum into a medium-frequency induction furnace for remelting, with a waste aluminum recovery rate ≥95%; collect dust generated during shot blasting, collect it through a bag filter, with a filtration efficiency ≥99.5%; collect waste liquid generated during surface treatment, discharge the waste liquid into a neutralization tank, add sodium hydroxide to the neutralization tank to adjust the pH value to 6.8; after adjustment, filter the waste liquid with a plate and frame filter press, with the filter press filtration pressure set to 0.6MPa; after treatment, test the moisture content of the filter residue, the moisture content of the filter residue ≤60%; test the COD value and heavy metal content of the treated wastewater, COD ≤50mg / L, heavy metal content ≤0.1mg / L.

[0054] S12. Finished product warehousing: 8mm thick antistatic pearl cotton is used to separate the machine casings. 10 machine casings are placed in each box, and the stacking height of each box is controlled to ≤3 layers. The storage warehouse is equipped with a constant temperature and humidity machine to control the warehouse temperature at 15-25℃ and the humidity at 40%-60%.

[0055] Example 2

[0056] This embodiment describes a manufacturing process for a lightweight aluminum alloy EPS motor housing, with the following specific steps:

[0057] S1. Material Pretreatment: Industrial-grade AlSi9MgMn aluminum alloy ingots are selected, with the purity of the ingots controlled at 99.8%. The aluminum alloy ingots are cut into 100mm×80mm×50mm blocks using a CNC saw. The blocks are placed in a box-type heating furnace, with the furnace temperature set at 350℃ and the holding time controlled at 30 minutes. After the holding time, the blocks are transferred to a four-column hydraulic press for pre-deformation treatment. The pressing rate of the hydraulic press is set at 5mm / s, and the pressing rate of the pre-deformation treatment is controlled at 13.5%. After the treatment, the forced air cooling system of the furnace is turned on, with the air velocity of the forced air cooling system set at 2.5m / s, and the material is allowed to cool naturally to room temperature. During the cooling process, the internal temperature of the material is monitored in real time using thermocouples, and the internal temperature gradient of the material is controlled at ≤5℃ / cm.

[0058] S2. Gradient Melting: The pretreated aluminum alloy block is placed into a medium-frequency induction furnace. The initial temperature of the medium-frequency induction furnace is set to 450℃, and the holding time is controlled at 1 hour. During the holding period, the furnace stirring device is turned on every 15 minutes, and the stirring speed is controlled at 60 r / min to ensure uniform heating of the alloy. Then, the furnace temperature is raised to 710℃ at a rate of 9℃ / min. During the heating process, La-Ce composite microalloys are added, with the addition amount controlled at 0.10% and the mass ratio of La to Ce being 1:1.2. When adding, the microalloys are wrapped in aluminum foil with a thickness of 0.1mm and added through the furnace feeding port. After addition, stirring is continued for 30 minutes. After stirring, the alloy composition is detected by a spectrometer. The Fe content in the alloy is ≤0.15%, the Cu content is ≤0.08%, and the rare earth residue is controlled at 0.075%.

[0059] S3. Vacuum Die Casting: The molten aluminum is transferred to a heat preservation tank, where the temperature is maintained at 700℃, and the density of the molten aluminum must be ≥2.61g / cm³. The molten aluminum is then transferred to a vacuum die casting machine. The vacuum system of the die casting machine is first activated, and the vacuum level inside the machine is evacuated to 50mbar and maintained for 5 seconds. The die casting mold is pre-installed with conformal cooling water channels. The diameter of the cooling water pipes is 8mm, and the pipe spacing is 15mm. Circulating water at 28℃ is introduced into the cooling water channels. The surface of the mold cavity is treated with… Plasma spraying equipment is used to spray an Al2O3-TiO2 composite coating. The mass ratio of Al2O3 to TiO2 in the coating is 7:3. The spraying current is set to 380A, the spraying distance is controlled at 120mm, and the coating thickness is controlled at 6.5μm. The die-casting machine parameters are adjusted, with the feeding pressure set to 35MPa, the injection speed controlled at 80mm / s, the clamping force set to 4000kN, and the molding cycle controlled at 75 seconds / piece. After molding, a shell blank with a wall thickness difference ≤0.8mm is obtained.

[0060] S4. Deburring: Fix the machine housing blank on the CNC milling machine worktable; select an ER16 CNC milling cutter with a cutting diameter of 6mm, set the milling speed to 1500mm / min, and control the feed rate at 0.15mm / r to remove coarse burrs ≥0.5mm through milling; after removing the coarse burrs, transfer the machine housing to a laser deburring machine; the laser deburring machine uses a 1064nm fiber laser, sets the laser power to 17.5W, and controls the scanning speed at 900mm / s; use a CCD vision positioning system to lock the micro-holes ≤2mm in diameter and the fine burrs at the corners on the machine housing, and remove the fine burrs point by point, finally controlling the deburring accuracy to 0.02mm.

[0061] S5. Shot blasting strengthening: The deburred casing is placed into a tracked shot blasting machine; steel shot and ceramic shot are mixed at a mass ratio of 3:1, with steel shot diameter of 0.7mm and hardness of HRC52, and ceramic shot diameter of 0.4mm and hardness of HV1200; the shot blasting machine pressure is first set to 0.5MPa, and the shot blasting machine speed is controlled at 1200r / min for 2.5 minutes of rough blasting; after the rough blasting is completed, the pressure is kept constant and fine blasting is continued for 2.5 minutes; after shot blasting, the surface roughness of the casing is tested by a surface roughness meter, and the surface roughness reaches Ra1.2-1.6μm; then the residual compressive stress on the surface of the casing is tested by an X-ray stress meter, and the residual compressive stress is ≥120MPa.

[0062] S6. Composite Heat Treatment: The shot-blasted casing is sent to a continuous heat treatment furnace for T5 basic heat treatment; the heating rate of the heat treatment furnace is set to 10℃ / min, and the temperature is held at 205℃ for 4.5 hours; after the holding period, it is cooled to room temperature at a rate of 8℃ / min; after cooling, local induction heating is performed on the bearing mounting position and terminal interface of the casing. The diameter of the bearing mounting position hole is φ75mm, and the diameter of the terminal interface is φ12mm; the frequency of the local induction heating equipment is set to 17.5kHz, the heating temperature is controlled at 220℃, the coil moving speed is set to 5mm / s, and the aging time is controlled at 17.5 minutes; after aging treatment, the hardness of the casing is tested by a Vickers hardness tester. The hardness of the key parts reaches HV110-120, and the hardness of the non-critical parts remains at HV95-105.

[0063] S7. Precision Milling: The heat-treated machine housing is clamped in a CNC machining center; a carbide end mill with an AlCrN coating is selected, conforming to the TCMT16T304 specification; rough milling is performed first, with a cutting speed set to 900 m / min, feed rate controlled at 0.18 mm / r, and depth of cut set to 2 mm; after rough milling, semi-finish milling is performed, with a cutting speed set to 1000 m / min, feed rate controlled at 0.15 mm / r, and depth of cut set to... The milling depth is set to 0.8mm. After semi-finish milling, finish milling is performed. During finish milling, the machine tool's real-time vibration monitoring system is turned on, and the vibration sensor detection accuracy meets the requirement of amplitude ≤0.005mm. The finish milling cutting speed is set to 925m / min, the feed rate is controlled at 0.14mm / r, and the cutting depth is set to 0.3mm. After finish milling, the machine housing dimensions are checked by a coordinate measuring machine. The inner hole size reaches φ75mm±0.008mm, and the flatness of the mounting surface is controlled at ≤0.01mm / 100mm.

[0064] S8. Multi-dimensional Leak Detection: First, use compressed air to purge the inside of the casing. The compressed air pressure is set to 0.3MPa, and the purging time is controlled at 15 seconds to remove oil and debris from the inside of the casing. After purging, the casing is transferred to the water pressure testing station. After sealing the casing, 0.8 bar of compressed air is introduced, and the pressure holding time is controlled at 45 seconds. The leakage is monitored by a differential pressure sensor. After the water pressure test, the casing is transferred to the helium mass spectrometry leak detection station. A helium mass spectrometer leak detector is used for detection. The leak detector is set to a negative pressure of -0.08MPa, and the pressure holding time is controlled at 65 seconds. The leak detection accuracy reaches 5×10⁻⁻⁻⁶. 9 Pa·m³ / s.

[0065] S9. Micro-arc oxidation surface treatment: Prepare a silicate-phosphate composite electrolyte with Na2SiO3 content of 80g / L, Na3PO4 content of 30g / L, and NaF content of 0.5g / L; pour the prepared electrolyte into a micro-arc oxidation tank; place the casing as the anode and the stainless steel plate as the cathode into the micro-arc oxidation tank; set the micro-arc oxidation parameters: pulse voltage of 375V, frequency of 500Hz, duty cycle of 30%, and treatment time of 20 minutes; after treatment, remove the casing and clean it with deionized water (conductivity ≤5μS / cm), repeat the cleaning 3 times, and each cleaning time is 5 minutes; after cleaning, immerse the casing in a sealing agent with a nano-SiO2 concentration of 6.5% for 10 minutes; after immersion, allow it to air dry naturally.

[0066] S10. Structural Verification: A 3D model of the casing was created using ABAQUS 2022 software. The casing constraints were set to "fixed at both ends - suspended in the middle" in the software. A high-temperature load of 150℃ and a vibration load of 1500rpm were applied. The vibration load was a sine wave with an acceleration of 10g to simulate the stress distribution of the casing. At the same time, 5 finished casings were sampled and placed on a vibration test bench for physical vibration testing. The test frequency range was 10-2000Hz. After the test, the casing was checked for cracks and deformation. The appearance of the casing was then inspected using a colorimeter. The casing was free of scratches and the color difference ΔE ≤ 0.8. After all dimensions passed the inspection, the casing was packaged.

[0067] S11. Environmental Protection Treatment: Collect waste aluminum generated during the die casting process, place the waste aluminum in a drying oven, set the drying oven temperature to 120℃, and control the drying time to 2 hours; after drying, put the waste aluminum into a medium-frequency induction furnace for remelting, with a waste aluminum recovery rate ≥95%; collect dust generated during shot blasting, collect it through a bag filter, with a filtration efficiency ≥99.5%; collect waste liquid generated during surface treatment, discharge the waste liquid into a neutralization tank, add sodium hydroxide to the neutralization tank to adjust the pH value to 6.8; after adjustment, filter the waste liquid with a plate and frame filter press, with the filter press filtration pressure set to 0.6MPa; after treatment, test the moisture content of the filter residue, the moisture content of the filter residue ≤60%; test the COD value and heavy metal content of the treated wastewater, COD ≤50mg / L, heavy metal content ≤0.1mg / L.

[0068] S12. Finished product warehousing: 8mm thick antistatic pearl cotton is used to separate the machine casings. 10 machine casings are placed in each box, and the stacking height of each box is controlled to ≤3 layers. The storage warehouse is equipped with a constant temperature and humidity machine to control the warehouse temperature at 15-25℃ and the humidity at 40%-60%.

[0069] Example 3

[0070] This embodiment describes a manufacturing process for a lightweight aluminum alloy EPS motor housing, with the following specific steps:

[0071] S1. Material Pretreatment: Industrial-grade AlSi9MgMn aluminum alloy ingots are selected, with the purity of the ingots controlled at 99.8%. The aluminum alloy ingots are cut into 100mm×80mm×50mm blocks using a CNC saw. The blocks are placed in a box-type heating furnace, with the furnace temperature set at 350℃ and the holding time controlled at 30 minutes. After the holding time, the blocks are transferred to a four-column hydraulic press for pre-deformation treatment. The pressing speed of the hydraulic press is set at 5mm / s, and the reduction rate of the pre-deformation treatment is controlled at 15%. After the treatment, the forced air cooling system of the furnace is turned on, with the air speed of the forced air cooling system set at 3m / s, and the material is allowed to cool naturally to room temperature. During the cooling process, the internal temperature of the material is monitored in real time using thermocouples, and the internal temperature gradient of the material is controlled at ≤5℃ / cm.

[0072] S2. Gradient Melting: The pretreated aluminum alloy block is placed into a medium-frequency induction furnace. The initial temperature of the medium-frequency induction furnace is set to 450℃, and the holding time is controlled at 1 hour. During the holding period, the furnace stirring device is turned on every 15 minutes, and the stirring speed is controlled at 60 r / min to ensure uniform heating of the alloy. Then, the furnace temperature is raised to 710℃ at a rate of 10℃ / min. During the heating process, La-Ce composite microalloys are added, with the addition amount controlled at 0.12% and the mass ratio of La to Ce being 1:1.2. When adding, the microalloys are wrapped in aluminum foil with a thickness of 0.1mm and added through the furnace feeding port. After addition, stirring is continued for 30 minutes. After stirring, the alloy composition is detected by a spectrometer. The Fe content in the alloy is ≤0.15%, the Cu content is ≤0.08%, and the rare earth residue is controlled at 0.09%.

[0073] S3. Vacuum Die Casting: The molten aluminum is transferred to a heat preservation tank, where the temperature is maintained at 700℃, and the density of the molten aluminum must be ≥2.61g / cm³. The molten aluminum is then transferred to a vacuum die casting machine. The vacuum system of the die casting machine is first activated, and the vacuum level inside the machine is evacuated to 50mbar and maintained for 5 seconds. The die casting mold is pre-installed with conformal cooling water channels. The diameter of the cooling water pipes is 8mm, and the pipe spacing is 15mm. Circulating water at 28℃ is introduced into the cooling water channels. The mold cavity surface is... An Al2O3-TiO2 composite coating was applied using plasma spraying equipment. The mass ratio of Al2O3 to TiO2 in the coating was 7:3. The spraying current was set to 380A, the spraying distance was controlled at 120mm, and the coating thickness was controlled at 8μm. The die-casting machine parameters were adjusted, with the material feeding pressure set to 35MPa, the injection speed controlled at 80mm / s, the clamping force set to 4000kN, and the molding cycle controlled at 80 seconds / piece. After molding, a housing blank with a wall thickness difference ≤0.8mm was obtained.

[0074] S4. Deburring: Fix the machine housing blank on the CNC milling machine worktable; select an ER16 CNC milling cutter with a cutting diameter of 6mm, set the milling speed to 1500mm / min, and control the feed rate at 0.15mm / r to remove coarse burrs ≥0.5mm through milling; after removing the coarse burrs, transfer the machine housing to a laser deburring machine; the laser deburring machine uses a 1064nm fiber laser, sets the laser power to 20W, and controls the scanning speed at 1000mm / s; use a CCD vision positioning system to lock the micro-holes ≤2mm in diameter and the fine burrs at the corners on the machine housing, and remove the fine burrs point by point, finally controlling the deburring accuracy to 0.02mm.

[0075] S5. Shot blasting strengthening: The deburred casing is placed into a tracked shot blasting machine; steel shot and ceramic shot are mixed at a mass ratio of 3:1, with steel shot diameter of 0.8mm and hardness of HRC52, and ceramic shot diameter of 0.5mm and hardness of HV1200; the shot blasting machine pressure is first set to 0.5MPa, and the shot blasting machine speed is controlled at 1200r / min for 3.5 minutes of rough blasting; after the rough blasting is completed, the pressure is kept constant and fine blasting is continued for 1.5 minutes; after shot blasting, the surface roughness of the casing is tested by a surface roughness meter, and the surface roughness reaches Ra1.2-1.6μm; then the residual compressive stress on the surface of the casing is tested by an X-ray stress meter, and the residual compressive stress is ≥120MPa.

[0076] S6. Composite Heat Treatment: The shot-blasted casing is sent to a continuous heat treatment furnace for T5 basic heat treatment; the heating rate of the heat treatment furnace is set to 10℃ / min, and the temperature is held at 205℃ for 4.5 hours; after the holding period, it is cooled to room temperature at a rate of 8℃ / min; after cooling, local induction heating is performed on the bearing mounting position and terminal interface of the casing. The diameter of the bearing mounting position hole is φ75mm, and the diameter of the terminal interface is φ12mm; the frequency of the local induction heating equipment is set to 20kHz, the heating temperature is controlled at 220℃, the coil moving speed is set to 5mm / s, and the aging time is controlled at 20 minutes; after aging treatment, the hardness of the casing is tested by a Vickers hardness tester. The hardness of the key parts reaches HV110-120, and the hardness of the non-critical parts remains at HV95-105.

[0077] S7. Precision Milling: The heat-treated machine housing is clamped in a CNC machining center; a carbide end mill with an AlCrN coating is selected, conforming to the TCMT16T304 specification; rough milling is performed first, with a cutting speed set to 900 m / min, feed rate controlled at 0.18 mm / r, and depth of cut set to 2 mm; after rough milling, semi-finish milling is performed, with a cutting speed set to 1000 m / min, feed rate controlled at 0.15 mm / r, and depth of cut set to... The milling depth is set to 0.8mm. After semi-finish milling, finish milling is performed. During finish milling, the machine tool's real-time vibration monitoring system is turned on, and the vibration sensor detection accuracy meets the requirement of amplitude ≤0.005mm. The finish milling cutting speed is set to 950m / min, the feed rate is controlled at 0.16mm / r, and the cutting depth is set to 0.3mm. After finish milling, the machine housing dimensions are checked by a coordinate measuring machine. The inner hole dimension reaches φ75mm±0.008mm, and the flatness of the mounting surface is controlled at ≤0.01mm / 100mm.

[0078] S8. Multi-dimensional Leak Detection: First, use compressed air to purge the inside of the casing. The compressed air pressure is set to 0.3MPa, and the purging time is controlled at 15 seconds to remove oil and debris from the inside of the casing. After purging, transfer the casing to the water pressure testing station. After sealing the casing, introduce 0.8 bar compressed air and hold the pressure for 50 seconds. Monitor the leakage amount using a differential pressure sensor. After the water pressure test, transfer the casing to the helium mass spectrometry leak detection station. Use a helium mass spectrometer leak detector to detect the leak. The leak detector is set to a negative pressure of -0.08MPa, and the holding time is controlled at 70 seconds. The leak detection accuracy reaches 5×10⁻⁻⁻⁶. 9 Pa·m³ / s.

[0079] S9. Micro-arc oxidation surface treatment: Prepare a silicate-phosphate composite electrolyte with Na2SiO3 content of 80g / L, Na3PO4 content of 30g / L, and NaF content of 0.5g / L; pour the prepared electrolyte into a micro-arc oxidation tank; place the casing as the anode and the stainless steel plate as the cathode into the micro-arc oxidation tank; set the micro-arc oxidation parameters: pulse voltage of 400V, frequency of 500Hz, duty cycle of 30%, and treatment time of 22 minutes; after treatment, remove the casing and clean it with deionized water (conductivity ≤5μS / cm), repeat the cleaning 3 times, and each cleaning time is 5 minutes; after cleaning, immerse the casing in a sealing agent with a nano-SiO2 concentration of 8% for 10 minutes; after immersion, allow it to air dry naturally.

[0080] S10. Structural Verification: A 3D model of the casing was created using ABAQUS 2022 software. The casing constraints were set to "fixed at both ends - suspended in the middle" in the software. A high-temperature load of 200℃ and a vibration load of 1500rpm were applied. The vibration load was a sine wave with an acceleration of 10g to simulate the stress distribution of the casing. At the same time, three finished casings were sampled and placed on a vibration test bench for physical vibration testing. The test frequency range was 10-2000Hz. After the test, the casing was checked for cracks and deformation. The appearance of the casing was then inspected using a colorimeter. The casing was free of scratches and the color difference ΔE ≤ 0.8. After all dimensions passed the inspection, the casing was packaged.

[0081] S11. Environmental Protection Treatment: Collect waste aluminum generated during the die casting process, place the waste aluminum in a drying oven, set the drying oven temperature to 120℃, and control the drying time to 2 hours; after drying, put the waste aluminum into a medium-frequency induction furnace for remelting, with a waste aluminum recovery rate ≥95%; collect dust generated during shot blasting, collect it through a bag filter, with a filtration efficiency ≥99.5%; collect waste liquid generated during surface treatment, discharge the waste liquid into a neutralization tank, add sodium hydroxide to the neutralization tank to adjust the pH value to 6.8; after adjustment, filter the waste liquid with a plate and frame filter press, with the filter press filtration pressure set to 0.6MPa; after treatment, test the moisture content of the filter residue, the moisture content of the filter residue ≤60%; test the COD value and heavy metal content of the treated wastewater, COD ≤50mg / L, heavy metal content ≤0.1mg / L.

[0082] S12. Finished product warehousing: 8mm thick antistatic pearl cotton is used to separate the machine casings. 10 machine casings are placed in each box, and the stacking height of each box is controlled to ≤3 layers. The storage warehouse is equipped with a constant temperature and humidity machine to control the warehouse temperature at 15-25℃ and the humidity at 40%-60%.

[0083] Comparative Example

[0084] This comparative example uses traditional processes to produce the EPS motor housing. The specific steps are as follows:

[0085] S1. Material preparation: AlSi12 aluminum alloy is selected without pre-deformation treatment; the aluminum alloy is cut into blocks by CNC sawing machine and directly transferred to the melting process.

[0086] S2. Smelting process: The block material is put into a medium-frequency induction furnace and heated at a single temperature of 680℃ without a gradient heating process; no La-Ce composite microalloying is added during smelting; after smelting, the alloy composition is tested and the Fe content is 0.2% and the Cu content is 0.12%; no rare earth elements are added.

[0087] S3. Die casting: The die casting machine is used for molding, without vacuum treatment; the die casting mold does not have a conformal cooling water channel, and only ordinary cooling is used; the mold cavity surface is not coated; the die casting machine parameters are adjusted, the feeding pressure is set to 30MPa, and the molding cycle is controlled at 90 seconds / piece; the thickness difference of the blank wall after molding is 1.2mm.

[0088] S4. Deburring: Deburring is done by mechanical milling only, using a common CNC milling cutter with milling parameters consistent with Example 1; it cannot remove the fine burrs at the micro-holes and corners of the housing.

[0089] S5. Shot blasting: Shot blasting is performed using a single steel shot with a diameter of 1 mm and a hardness of HRC52; the shot blasting machine pressure is set to 0.4 MPa and the processing time is controlled within 4 minutes; there is no segmented blasting process; the surface roughness of the machine shell after shot blasting does not reach Ra1.2-1.6 μm, and there is no effect on improving the surface residual compressive stress.

[0090] S6. Heat treatment: The integral T5 heat treatment is adopted. The casing is placed in the heat treatment furnace, the temperature is set to 200℃, and the holding time is controlled at 4 hours. There is no local induction heating strengthening process. After heat treatment, the overall hardness uniformity of the casing is poor, and the hardness of key parts does not reach HV110-120.

[0091] S7. Machining: Machining was performed using ordinary carbide end mills without AlCrN coating; there was no real-time vibration monitoring or dimensional compensation during machining; after machining, the internal hole dimensional accuracy and the flatness of the mounting surface were not met by a coordinate measuring machine and did not meet the requirements of Example 1.

[0092] S8. Leakage detection: Only water pressure testing is performed, with the water pressure set at 0.6 bar and the pressure holding time controlled at 30 seconds; there is no helium mass spectrometry leak detection process; it is impossible to fully investigate the risk of leakage in the casing.

[0093] S9. Surface treatment: Ordinary anodizing is used, with an oxide film thickness of 10μm; no sealing process is required; the casing has poor corrosion resistance after treatment.

[0094] S10. Inspection and Packaging: Only simple appearance and size inspections are performed, without finite element simulation and physical vibration testing; after passing the inspection, the product is directly packaged without anti-static separation measures.

[0095] S11. Environmental Protection and Storage: Waste aluminum from die casting is collected and directly smelted without drying treatment; the waste aluminum recovery rate is 85%; there is no special collection device for shot blasting dust; surface treatment waste liquid is discharged directly without neutralization and precipitation treatment; the storage warehouse has no constant temperature and humidity control and is only stored in a normal environment.

[0096] The core performance indicators of the examples and comparative examples are compared in the table below:

[0097] Table 1

[0098] Indicator Name Example 1 Example 2 Example 3 Comparative Example Casing weight (taking the φ75mm inner hole model as an example, kg) 1.1 1.08 1.05 1.2 Hardness of critical components (bearing mounting location, HV) 115 118 120 93 Overall tensile strength (MPa) 235 240 245 190 Overall yield strength (MPa) 188 192 195 150 Resistance to neutral salt spray (GB / T 10125, hours) 520 (No rust) 540 (No rust) 560 (No rust) 200 (Pitted corrosion appears) Sealing performance (leakage, mL / min) 0.6 0.5 0.4 3.2 Maximum wall thickness difference (mm) 0.6 0.5 0.4 1.2 Inner hole dimensional accuracy (φ75mm, mm) φ75±0.006 φ75±0.005 φ75±0.004 φ75±0.020 Mounting surface flatness (100mm length, mm / 100mm) 0.008 0.007 0.006 0.030

[0099] The specific performance comparisons between the examples and comparative examples are shown in the table below:

[0100] Table 2

[0101] Indicator Name Example 1 Example 2 Example 3 Comparative Example Molding cycle (per piece, seconds) 70 75 80 90 Product qualification rate (100 samples, %) 99.5 99.8 100 90.0 Aluminum scrap recycling rate (%) 96.2 96.5 97.0 85.0 Shot blasting dust collection efficiency (%) 99.6 99.7 99.8 60.0 COD value of surface treatment wastewater (mg / L) 42 40 38 155 Heavy metal content (Pb+Cd, mg / L) in surface treatment wastewater 0.06 0.05 0.04 0.62 Energy consumption per unit of product (kWh / unit) 8.5 8.7 8.9 11.2 Environmental compliance items (GB / T 21967-2008, item) All standards met (all 6 items passed) All standards met (all 6 items passed) All standards met (all 6 items passed) Four items failed to meet the standards (COD / heavy metals / dust / waste residue).

[0102] In summary, the performance comparison data in the two tables clearly demonstrate that the lightweight aluminum alloy EPS motor housing manufacturing process proposed in this invention has comprehensive advantages over traditional processes. In terms of core performance, Examples 1-3, through material optimization, gradient melting, and composite heat treatment, achieve a housing weight reduction of 8.3%-11.4%, while significantly improving the hardness, tensile strength, and yield strength of key components. The neutral salt spray resistance is 2.6-2.8 times that of the comparative example, and the sealing performance, wall thickness difference control, and dimensional accuracy also far exceed those of the comparative example, fully meeting the requirements of new energy vehicles for lightweight, high-strength, and high-reliability components.

[0103] In terms of production and environmental performance, the prototype has a shorter molding cycle, a product qualification rate of over 99.5%, a significantly higher waste aluminum recycling rate and dust collection efficiency than the comparative example, and the COD value and heavy metal content of the surface treatment wastewater are only 1 / 3 to 1 / 15 of the comparative example. The unit product energy consumption is reduced by 31.8%, and all of them meet environmental protection standards, while the comparative example has 4 environmental compliance issues.

[0104] Overall, the process of this invention takes into account product performance, production efficiency and environmental protection requirements, and has significant technological advancement and application value compared with traditional processes.

[0105] 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 manufacturing process for a lightweight aluminum alloy EPS motor housing, characterized in that, Includes the following steps: S1. Material pretreatment: Lightweight aluminum alloy is selected and pre-deformed at 350℃±10℃. The reduction rate of the pre-deformation treatment is 12%-15%. After holding at the temperature for 30-40 minutes, it is naturally cooled. S2. Gradient melting: The pretreated aluminum alloy is put into a medium-frequency induction furnace and a "low-temperature preheating-gradient heating" mode is adopted; La-Ce composite microalloying is added during the heating process; The "low-temperature preheating-gradient heating" mode in S2 specifically involves maintaining an initial temperature of 450℃±10℃ for 1 hour, followed by heating to 710℃±5℃ at a rate of 8-10℃ / min; the mass ratio of La to Ce in the La-Ce composite microalloy is 1:1.2; aluminum foil is used to wrap the microalloy when it is added, with a foil thickness of 0.1mm; and the rare earth residual content in the alloy is ultimately controlled within the range of 0.06%-0.09%. S3. Vacuum die casting: The molten aluminum liquid is transferred to a vacuum die casting machine; the die casting machine is first evacuated to ≤50mbar, and then the aluminum liquid is injected with a feeding pressure of 35MPa. The die casting mold adopts a conformal cooling water channel, and finally a shell blank with a wall thickness difference of ≤0.8mm is obtained. S4. Deburring: A composite process of "mechanical milling + laser deburring" is adopted; first, coarse burrs ≥0.5mm are removed by CNC milling cutter, and then fine burrs at micro-holes and corners are removed by 1064nm fiber laser. S5. Shot blasting strengthening: A mixture of steel shot and ceramic shot is used for blasting, with a mass ratio of 3:1; the diameter of the steel shot is 0.6-0.8mm, and the diameter of the ceramic shot is 0.3-0.5mm; the blasting is divided into two stages, the first stage is 3 minutes of rough blasting, and the second stage is 2 minutes of fine blasting; S6. Composite heat treatment: First, perform T5 basic heat treatment at a temperature of 205℃±3℃; then, perform local induction heating on the housing bearing mounting position and terminal interface. The induction heating in S6 has a frequency of 15-20kHz, a temperature of 220℃±5℃, and an aging time of 15-20min. It uses a ring induction coil with an inner diameter 2-3mm larger than the part to be heated. During the heating process, the coil moves at a speed of 5-6mm / s, and the temperature of the heating zone is monitored in real time with a temperature measurement accuracy of ±2℃. The hardness uniformity error of key parts is precisely controlled to be ≤5HV. S7. Precision Milling: Carbide end mills are used for three-stage machining in a CNC machining center: rough milling, semi-finish milling, and finish milling. The rough milling cutting speed is 900-950 m / min, and the feed rate is 0.18-0.2 mm / r. Real-time vibration monitoring is introduced during finish milling. Dimensional compensation machining is performed on the inner holes and mounting surfaces of the machine housing. S8. Multi-dimensional Leak Detection: First, compressed air is used to purge the inside of the casing; then, the detection is carried out at two different workstations. S9. Micro-arc oxidation surface treatment: using a silicate-phosphate composite electrolyte, treatment is performed under pulse voltage; after treatment, an oxide film is formed with a thickness of 15-18μm; subsequently, it is immersed in a sealing agent; S10. Structural Verification: The finished casing undergoes a combined verification of "lightweighting and strength" by testing its stress distribution through finite element simulation; the weight of the casing is also measured; and finally, the casing undergoes a full inspection of its appearance and dimensions. S11. Environmental protection treatment: Collect the waste aluminum slag generated during the die casting process, dry it at 120℃, and then remelt it. Dust generated during shot blasting is collected using a bag filter; waste liquid generated during surface treatment is neutralized and precipitated to adjust the pH to 6.8-7.2 before being discharged in compliance with standards. S12. Finished product warehousing: Anti-static pearl cotton is used for separation and packaging, and the stacking height of each box is ≤3 layers; the storage environment temperature is controlled at 15-25℃ and the humidity is controlled at 40%-60%.

2. The manufacturing process for the lightweight aluminum alloy EPS motor housing according to claim 1, characterized in that, The pre-deformation process in S1 uses a four-column hydraulic press, with the pressing rate controlled at 5-8 mm / s. Forced air cooling is used during natural cooling, with a wind speed of 2-3 m / s and an internal temperature gradient of ≤5℃ / cm.

3. The manufacturing process for the lightweight aluminum alloy EPS motor housing according to claim 1, characterized in that, The cooling water temperature in S3 is 28℃, and the mold cavity surface is coated with a nano-ceramic coating with a thickness of 5-8μm. The nano-ceramic coating is an Al2O3-TiO2 composite coating with a mass ratio of Al2O3 to TiO2 of 7:

3. The coating is prepared by plasma spraying.

4. The manufacturing process for the lightweight aluminum alloy EPS motor housing according to claim 1, characterized in that, The S7 uses a "size compensation algorithm" for precision milling; it first measures the actual machining dimensions of the first 5 housings with a measurement accuracy of 0.001mm; and then automatically adjusts the milling cutter feed based on the measurement results, with a feed compensation range of ±0.003mm.

5. The manufacturing process for the lightweight aluminum alloy EPS motor housing according to claim 1, characterized in that, The two testing stations in S8 are as follows: The first station performs a water pressure test at 0.8 bar for 40 seconds, with a leakage rate of <1 mL / min; the second station performs helium mass spectrometry leak detection with a detection accuracy of 5 × 10⁻⁻⁻⁶. 9 Pa·m³ / s; Before helium mass spectrometry leak detection, the casing is placed in a drying oven at a temperature of 80℃±5℃ for 2 hours; During detection, the "negative pressure helium absorption" mode is used with a negative pressure value of -0.08MPa and a holding time of 60s.

6. The manufacturing process for the lightweight aluminum alloy EPS motor housing according to claim 1, characterized in that, In step S9, the micro-arc oxidation electrolyte contains 80-90 g / L of Na2SiO3 and 30-35 g / L of Na3PO4. NaF is also added as a refining agent at a concentration of 0.5 g / L. After oxidation treatment, the casing is cleaned with deionized water three times for 5 minutes each time.

7. The manufacturing process for the lightweight aluminum alloy EPS motor housing according to claim 1, characterized in that, In the S10 finite element simulation, ABAQUS software was used. During the simulation, the casing constraint conditions were set as "fixed at both ends and suspended in the middle". The vibration load was a sine wave with a sine wave acceleration of 10g. At the same time, three finished products were sampled for physical vibration testing, with a test frequency range of 10-2000Hz. After the test, the casing was required to be free of cracks.

8. The manufacturing process for the lightweight aluminum alloy EPS motor housing according to claim 1, characterized in that, Before smelting, the waste aluminum slag in S11 needs to be magnetically separated to remove iron. The magnetic field strength of the magnetic separation equipment is 12000-15000Gs. After neutralization, the surface treatment waste liquid is treated by a plate and frame filter press with a filtration pressure of 0.6MPa.

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