Electric engine assembly integral forming process based on precision integral casting

Abstract

The invention discloses an electric engine assembly integral forming process based on precision integral casting, which comprises the following steps: designing a split type precision mold through computer aided design software, and carrying out nitriding treatment to improve the performance; selecting a specific aluminum alloy raw material, performing vacuum induction melting and refining, and injecting the aluminum alloy raw material into a preheated and sprayed mold cavity in a low-pressure casting manner; and demolding after air cooling and water cooling are combined, then after-treatment procedures such as deburring and heat treatment are conducted, and finally detection and assembly are conducted. A conformal cooling water channel design and an ultrasonic-assisted smelting technology are adopted in the process innovation, and the casting process is monitored in real time. According to the process, manufacturing procedures are reduced, compared with a traditional mode, the production efficiency is improved by 30%-50%, the cost is reduced by 20%-30%, the assembling problem is effectively avoided, the sealing performance and reliability of the electric engine are improved, the service life of the electric engine is prolonged, high integration is achieved, and the modern industrial requirement is met.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of electric motor manufacturing, in particular to an integrated forming process of an electric motor assembly based on precision integral casting. BACKGROUND

[0002] In the manufacturing process of an electric motor, the traditional electric motor assembly manufacturing usually adopts the mode of separately processing multiple parts and then assembling them. This manufacturing mode has many drawbacks. On the one hand, the separate processing of multiple parts increases the manufacturing process and time cost, resulting in low production efficiency. On the other hand, the assembly of parts requires a large number of connecting pieces such as bolts, nuts, etc., which not only increases the overall weight but also easily causes problems such as loose connection and poor sealing during use, affecting the performance and reliability of the electric motor and thus reducing the service life of the electric motor. In addition, the traditional assembly method is difficult to achieve precise matching of the complex structure inside the electric motor, which is not conducive to improving the integration and performance optimization of the electric motor. With the development of electric motors towards miniaturization, high efficiency and high integration, the traditional manufacturing method has been difficult to meet the needs of modern industry, and a new manufacturing process is needed to solve the above problems. SUMMARY

[0003] The purpose of the present application is to provide an integrated forming process of an electric motor assembly based on precision integral casting, which can reduce the manufacturing process of the electric motor, improve production efficiency and reduce production cost. At the same time, it avoids the connection problems caused by the assembly of parts, improves the sealing, reliability and service life of the electric motor, and realizes the high integration and high performance of the electric motor.

[0004] In order to achieve the above purpose, the present application is realized by the following technical scheme: an integrated forming process of an electric motor assembly based on precision integral casting, comprising the following steps: Step S1, use computer-aided design software to perform three-dimensional modeling, and design a precision integral casting mold with a split structure. The parts of the precision integral casting mold are precisely positioned by high-precision positioning pins and positioning grooves. The material of the precision integral casting mold is selected from mold steel with high heat resistance, high wear resistance and good heat conductivity, and the surface of the precision integral casting mold is subjected to nitriding treatment; Step S2, select aluminum alloy material with high strength, high thermal conductivity and good electromagnetic properties as the casting raw material, and cut the aluminum alloy raw material into appropriate size after quality detection; Step S3, place the aluminum alloy raw material into a vacuum induction melting furnace and melt under argon protection. After melting, add a refining agent for refining treatment, and then stand still after refining is completed; Step S4, preheat the precision integral casting mold in a preheating furnace, and after preheating is completed, spray a special casting coating on the surface of the mold cavity. Step S5, slowly inject the aluminum alloy liquid into the mold cavity by the low-pressure casting machine at a pressure of 0.01-0.03 MPa, control the filling speed at 10-20 cm / s, and keep the pressure at 0.01-0.03 MPa after filling to maintain pressure; Step S6, cool the precision integral casting mold by combining air cooling and water cooling, and demold after cooling; Step S7, deburr, heat treat, and surface treat the demolded casting; Step S8, comprehensively detect the casting, and assemble it with other matching parts after detection.

[0005] Further as an improvement of the technical scheme of the application, the precision error of the precision integral casting mold is not more than ±0.05 mm, and the thickness of the nitriding layer is controlled at 0.3-0.5 mm.

[0006] Further as an improvement of the technical scheme of the application, the aluminum alloy material is 6061 aluminum alloy, wherein the iron content is not more than 0.7%, and the silicon content is 0.4-0.8%.

[0007] Further as an improvement of the technical scheme of the application, in step S3, the temperature of smelting is controlled at 720-750℃, the addition amount of the refining agent is 0.3-0.5% of the mass of the aluminum alloy raw material, the refining time is 10-15 minutes, and the standing time is 5-10 minutes.

[0008] Further as an improvement of the technical scheme of the application, the preheating temperature of the precision integral casting mold is controlled at 200-250℃, the preheating time is 1-2 hours, the casting paint is water-based paint, and the thickness of the paint is controlled at 0.1-0.3 mm.

[0009] Further as an improvement of the technical scheme of the application, in step S5, the pressure maintaining time is 3-5 minutes.

[0010] Further as an improvement of the technical scheme of the application, in step S6, the air cooling speed is controlled at 10-20℃ / min, the water cooling speed is controlled at 20-30℃ / min, and the temperature of the casting is reduced to 100-150℃.

[0011] Further, as an improvement of the technical scheme of the present application, the heat treatment includes solution and aging heat treatment, the solution treatment temperature is controlled at 520-540 DEG C, the holding time is 2-3 hours, then water quenching is carried out, the quenching water temperature is controlled at 20-30 DEG C, after quenching, artificial aging treatment is carried out, the aging temperature is controlled at 170-190 DEG C, and the aging time is 6-8 hours.

[0012] Further, as an improvement of the technical scheme of the present application, in the design of the precision integral casting mold, a shape-following cooling water channel design is introduced, the diameter of the cooling water channel is controlled at 3-5 mm, and the water flow speed is controlled at 0.5-1 m / s.

[0013] Further, as an improvement of the technical scheme of the present application, in the aluminum alloy smelting process, an ultrasonic wave assisted smelting technology is adopted, the ultrasonic wave frequency is 20-40 kHz, and the power is 1-3 kW, and in the low-pressure casting process, the pressure and temperature changes inside the mold cavity are monitored in real time, and the casting process is adjusted in real time according to the preset process parameters.

[0014] The beneficial effects of the present application are as follows: Improve production efficiency: the present application adopts the precision integral casting one-piece forming process, which casts and forms multiple parts of the electric motor assembly through one time, reduces the manufacturing and assembly processes of the parts, greatly shortens the production cycle, and improves the production efficiency. Compared with the traditional manufacturing method, the production efficiency can be improved by 30%-50%. Reduce production cost: due to the reduction of manufacturing processes and the use of connecting parts, the raw material cost, processing cost and assembly cost are reduced. At the same time, the production efficiency is improved, and the production cost per unit product is further reduced. According to the calculation, the production cost of the electric motor assembly manufactured by the present application can be reduced by 20%-30%. Improve product quality: the one-piece forming process avoids the connection problems caused by part assembly, such as loose connection and poor sealing, improves the sealing and reliability of the electric motor. In addition, by optimizing the casting process and adopting innovative technologies such as shape-following cooling water channel design, ultrasonic wave assisted smelting technology and real-time monitoring and control technology, casting defects can be effectively reduced, the density, size accuracy and mechanical properties of the casting can be improved, and the overall performance and service life of the electric motor can be improved. According to the test, the service life of the electric motor manufactured by the present application can be improved by 20%-30% compared with the traditional manufacturing method. Realize high integration: the process of the application can realize the integral forming of the complex structure inside the electric motor, which is conducive to improving the integration of the electric motor and meeting the needs of the development of the electric motor in the direction of miniaturization, high efficiency and high integration. Through integral forming, the motor, controller, cooling system and other components of the electric motor can be reasonably integrated and designed, the internal structure layout of the electric motor is optimized, the space utilization is improved, and the overall weight is reduced. DETAILED DESCRIPTION

[0015] The application will be described in detail below with specific embodiments. The illustrative embodiments and descriptions of the application are used to explain the application, but not as a limitation of the application.

[0016] An integral forming process of an electric motor assembly based on precision integral casting, comprising the following steps: Mold design and manufacturing: according to the structure and performance requirements of the electric motor assembly, three-dimensional modeling is carried out by using computer aided design (SOLIDWORKS, UG, CAD) software, and a precision integral casting mold is designed. The mold adopts a split structure, including an upper mold, a lower mold and a plurality of side molds, and the molds are precisely positioned by high-precision positioning pins and positioning grooves to ensure that the precision error of the assembled mold is not more than ±0.05mm. The mold material is selected from mold steel with high heat resistance, high wear resistance and good heat conductivity, such as H13 steel, and the surface of the mold is subjected to nitriding treatment to improve the surface hardness and wear resistance of the mold. The thickness of the nitriding layer is controlled to be 0.3-0.5mm. Raw material preparation: aluminum alloy material with high strength, high thermal conductivity and good electromagnetic properties is selected as the casting raw material of the electric motor assembly, such as 6061 aluminum alloy. The aluminum alloy raw material is strictly quality tested to ensure that its chemical composition meets the national standard requirements, and the impurity content is controlled at a very low level, of which the iron content is not more than 0.7%, and the silicon content is between 0.4-0.8%. The aluminum alloy raw material is cut into blocks of appropriate size for subsequent melting. Melting and refining: the prepared aluminum alloy raw material is placed in a vacuum induction melting furnace for melting, and the melting temperature is controlled at 720-750℃. Argon is used for protection during the melting process to prevent oxidation of the aluminum alloy. After the aluminum alloy is completely melted, a refining agent is added for refining treatment, and the addition amount of the refining agent is 0.3-0.5% of the mass of the aluminum alloy raw material, and the refining time is 10-15 minutes to remove gas and impurities in the aluminum alloy liquid and improve the purity of the aluminum alloy liquid. After refining, stand for 5-10 minutes to allow impurities to fully precipitate. Mold preheating and spraying: Put the designed and manufactured mold into the preheating furnace for preheating, control the preheating temperature at 200-250℃, and the preheating time for 1-2 hours to ensure the uniformity of the mold temperature. After preheating, spray a layer of special casting paint on the surface of the mold cavity, the paint is water-based paint, and its main components include refractory materials, binders and suspending agents, and the paint thickness is controlled at 0.1-0.3mm. The purpose of spraying paint is to improve the demolding performance of the mold, prevent the aluminum alloy liquid from sticking to the mold surface, and at the same time, protect the mold. Low pressure casting: Pour the refined and static aluminum alloy liquid into the crucible of the low pressure casting machine, slowly inject the aluminum alloy liquid into the mold cavity preheated and sprayed with paint by the low pressure casting machine at a pressure of 0.01-0.03MPa, control the filling speed at 10-20cm / s to ensure that the aluminum alloy liquid fills the mold cavity smoothly and quickly, and avoid casting defects such as pores and slag inclusion. After the aluminum alloy liquid is filled, maintain the pressure at 0.01-0.03MPa for 3-5 minutes to allow the aluminum alloy liquid to fully compensate under the action of pressure and improve the density of the casting. Cooling and demolding: After the pressure holding is completed, cool the mold by combining air cooling and water cooling, first air cooling, control the cooling speed at 10-20℃ / min, when the casting temperature is reduced to 500-550℃, then water cooling, control the cooling speed at 20-30℃ / min, until the casting temperature is reduced to 100-150℃. After cooling, the casting is demolded from the mold through the demolding mechanism of the mold, and attention should be paid to avoid damaging the casting during demolding. Post-processing: The demolded electric motor assembly casting is subjected to post-processing, including deburring, heat treatment and surface treatment. First, use mechanical polishing and chemical corrosion to remove burrs and flash on the surface of the casting; then, the casting is subjected to solid solution aging heat treatment, the solid solution treatment temperature is controlled at 520-540℃, the holding time is 2-3 hours, then water quenching is carried out, the quenching water temperature is controlled at 20-30℃, after quenching, artificial aging treatment is carried out, the aging temperature is controlled at 170-190℃, and the aging time is 6-8 hours to improve the strength and hardness of the casting; finally, the casting is subjected to surface anodizing treatment, the thickness of the oxide film is controlled at 8-12μm to improve the corrosion resistance and aesthetics of the casting. Inspection and assembly: The post-processed electric motor assembly is comprehensively inspected, including size inspection, appearance inspection, mechanical property inspection, and electrical property inspection. The size inspection uses a three-coordinate measuring instrument to ensure that the size precision of the casting meets the design requirements, with a size error of not more than ±0.1 mm. The appearance inspection uses a combination of visual inspection and flaw detection to ensure that the casting surface is free of cracks, pores, sand holes, and other defects. The mechanical property inspection includes tensile testing, hardness testing, and impact testing to ensure that the mechanical properties of the casting meet the use requirements of the electric motor. The electrical property inspection includes insulation resistance testing, dielectric strength testing, and electrical conductivity testing to ensure that the electrical properties of the electric motor assembly are safe and reliable. After passing the inspection, the electric motor assembly is assembled with other matching parts to complete the manufacturing of the electric motor. In the above process, in order to further improve the performance and quality of the electric motor assembly, the following innovative technologies can also be used: In the mold design, a conformal cooling water channel design is introduced. According to the structural characteristics of the electric motor assembly, a conformal cooling water channel that matches the shape of the casting is designed inside the mold. By optimizing the layout and parameters of the cooling water channel, precise control of the cooling process of the casting is achieved, making the cooling of each part of the casting uniform, reducing casting stress, and improving the size accuracy and internal quality of the casting. The diameter of the cooling water channel is controlled at 3-5 mm, and the water flow speed is controlled at 0.5-1 m / s. During the aluminum alloy melting process, ultrasonic assisted melting technology is used to introduce a frequency of 20-40 kHz and a power of 1-3 kW of ultrasonic waves into the aluminum alloy liquid. The action of ultrasonic waves can promote the escape of gas and the agglomeration of impurities in the aluminum alloy liquid, further improving the purity of the aluminum alloy liquid, while refining the aluminum alloy grains and improving the mechanical properties of the casting. During the low-pressure casting process, the pressure and temperature changes inside the mold cavity are monitored in real time. The monitoring data is transmitted to the control system through pressure sensors and temperature sensors. The control system adjusts the casting process in real time according to the preset process parameters to ensure the stability of the casting process and the consistency of the casting quality.

[0017] The following will further illustrate the present application through various embodiments: Example 1 Mold design and manufacturing: CAD software is used to create a three-dimensional model of a certain type of electric motor assembly, and a split-type precision integral casting mold is designed. The upper mold, lower mold, and side mold are positioned by high-precision positioning pins and positioning grooves, with an accuracy error of ±0.03 mm. H13 steel is selected as the mold material, and the mold surface is treated with nitriding, with a nitriding layer thickness of 0.4 mm. Raw material preparation: 6061 aluminum alloy was selected as the casting raw material, and its chemical composition was detected. The iron content was 0.6%, and the silicon content was 0.6%, which met the standard requirements. The aluminum alloy raw material was cut into blocks of appropriate size. Melting and refining: The aluminum alloy raw material was placed in a vacuum induction melting furnace and melted at 730°C under argon protection. After melting, 0.4% by mass of a refining agent was added, and refining was carried out for 12 minutes, with 8 minutes of standing. Mold preheating and spraying: The mold was preheated in a preheating furnace at 220°C for 1.5 hours, and water-based casting paint was sprayed on the surface of the mold cavity to a thickness of 0.2mm. Low pressure casting: The aluminum alloy liquid was poured into the crucible of the low pressure casting machine, and was injected into the mold cavity at a pressure of 0.02MPa and a filling speed of 15cm / s. After filling, the pressure was maintained at 0.02MPa for 4 minutes. Cooling and demolding: First, air cooling was carried out at a cooling speed of 15°C / min. When the temperature of the casting dropped to 520°C, water cooling was carried out at a cooling speed of 25°C / min, until the temperature of the casting dropped to 120°C, and then demolding was carried out. Post-processing: The casting burrs and flash were removed, and solid solution and aging heat treatment was carried out at a solid solution temperature of 530°C for 2.5 hours, water quenching at a water temperature of 25°C, and artificial aging at a temperature of 180°C for 7 hours. Surface anodic oxidation treatment was carried out, with an oxide film thickness of 10μm. Detection and assembly: The casting was comprehensively detected using a three-coordinate measuring instrument, visual inspection, flaw detection, mechanical property detection equipment, and electrical property detection equipment. After passing the detection, the casting was assembled with other matching components.

[0018] Example 2 Mold design and manufacturing: SOLIDWORKS software was used to model another type of electric motor assembly, and a split mold was designed. The mold assembly precision error was ±0.04mm achieved through positioning pins and positioning grooves. The mold material was H13 steel, and the surface was nitrided, with a nitrided layer thickness of 0.35mm. Raw material preparation: 6061 aluminum alloy was selected, and its iron content was 0.5% and silicon content was 0.5%. The aluminum alloy was cut into blocks of appropriate size. Melting and refining: The aluminum alloy was melted in a vacuum induction melting furnace at 725°C under argon protection. After melting, 0.35% by mass of a refining agent was added, and refining was carried out for 13 minutes, with 7 minutes of standing. Mold preheating and spraying: The mold was preheated in a preheating furnace at 210°C for 1.2 hours, and water-based paint was sprayed on the surface of the cavity to a thickness of 0.15mm. Low pressure casting: The aluminum alloy liquid was injected into the crucible, and the mold was filled at a pressure of 0.015 MPa and a filling speed of 12 cm / s. The pressure was maintained at 0.015 MPa after filling for 3.5 minutes. Cooling and demolding: First, air cooling at a speed of 12℃ / min was performed, and when the temperature of the casting dropped to 510℃, water cooling at a speed of 22℃ / min was performed until the temperature dropped to 110℃ for demolding. Post-processing: After removing burrs and flash, solid solution treatment was performed at a temperature of 525℃ for 2.2 hours, water quenching (water temperature 22℃), artificial aging at 175℃ for 6.5 hours, and an anodic oxidation film thickness of 9μm. Detection and assembly: Professional equipment was used to complete various tests, and after passing the test, the qualified parts were assembled with the matching parts. Example 3 Mold design and manufacturing: SOLIDWORKS software was used to design the mold for the specific electric motor assembly, and the mold was designed in a split structure with a precision error of ±0.02mm. The surface of the H13 steel mold was nitrided, and the nitriding layer was 0.45mm. Raw material preparation: 6061 aluminum alloy raw material with an iron content of 0.65% and a silicon content of 0.7% was processed into a suitable block shape. Melting and refining: The raw material was melted in a vacuum induction melting furnace at 740℃ under argon protection, 0.45% refining agent was added, and the refining was performed for 14 minutes and the static state was maintained for 9 minutes. Mold preheating and spraying: The mold was preheated at 240℃ for 1.8 hours, and the mold cavity was coated with a 0.25mm thick water-based paint. Low pressure casting: The mold was filled at a pressure of 0.025 MPa and a speed of 18 cm / s, and the pressure was maintained at 0.025 MPa after filling for 4.5 minutes. Cooling and demolding: The air cooling speed was 18℃ / min, and when the casting temperature reached 540℃, the water cooling speed was 28℃ / min, and the demolding was performed at a temperature of 130℃. Post-processing: After processing the burrs, solid solution treatment was performed at 535℃ for 2.8 hours, quenching (water temperature 28℃), aging at 185℃ for 7.5 hours, and an anodic oxidation film thickness of 11μm. Detection and assembly: After completing the overall detection, the qualified parts were assembled. Example 4 Mold design and manufacturing: SOLIDWORKS software was used to design a new type of electric motor assembly mold, which was designed in a split structure with a precision error of ±0.01mm. The H13 steel mold had a nitriding layer of 0.5mm. Raw material preparation: 6061 aluminum alloy with an iron content of 0.4% and a silicon content of 0.45% was processed into a block shape for standby use. Melting and Refining: Vacuum induction melting at 750℃ with argon protection, addition of 0.5% refining agent, refining for 15 minutes, and standing for 10 minutes. Mold Preheating and Spraying: Preheating for 2 hours at 250℃, and coating the mold with 0.3mm water-based paint. Low-pressure Casting: Pressure of 0.03MPa, filling speed of 20cm / s, pressure holding of 0.03MPa after filling, and pressure holding for 5 minutes. Cooling and Demolding: Air cooling at 10℃ / min, water cooling at 30℃ / min when the casting is at 500℃, and demolding at 100℃. Post-processing: Deburring, solutionizing at 540℃ for 3 hours, quenching (water temperature of 20℃), aging at 190℃ for 8 hours, and anodic oxidation film thickness of 12μm. Inspection and Assembly: After strict inspection and qualification, assembly with other parts is completed.

[0019] In summary, the specific advantages of the present application are as follows: Improved production efficiency: The present application adopts a precise integral casting one-piece forming process, which casts and forms multiple parts of the electric motor assembly through one casting, reduces the processes of separate machining and assembly of parts, greatly shortens the production cycle, and improves the production efficiency. Compared with the traditional manufacturing method, the production efficiency can be improved by 30%-50%. Reduced production cost: Due to the reduction of manufacturing processes and the use of connecting parts, the raw material cost, processing cost and assembly cost are reduced. At the same time, the production efficiency is improved, and the production cost per unit product is further reduced. According to the calculation, the production cost of the electric motor assembly manufactured by the process of the present application can be reduced by 20%-30%. Improved product quality: The one-piece forming process avoids the connection problems caused by part assembly, such as loose connection and poor sealing, improves the sealing and reliability of the electric motor. In addition, through the optimization of the casting process and the use of innovative technologies such as the design of the conformal cooling water channel, ultrasonic assisted melting technology and real-time monitoring and control technology, casting defects can be effectively reduced, the density, dimensional accuracy and mechanical properties of the casting can be improved, and thus the overall performance and service life of the electric motor can be improved. According to the test, the service life of the electric motor manufactured by the process of the present application can be improved by 20%-30% compared with the traditional manufacturing method. High integration: The process of the present application can realize the one-piece forming of the complex structure inside the electric motor, which is beneficial to improve the integration of the electric motor and meet the needs of the development of the electric motor towards miniaturization, high efficiency and high integration. Through one-piece forming, the motor, controller, cooling system and other parts of the electric motor can be reasonably integrated and designed, the internal structure layout of the electric motor can be optimized, the space utilization rate can be improved, and the overall weight can be reduced.

[0020] The above describes the technical solutions provided by the embodiments of the present application in detail. The principles and implementation manners of the embodiments of the present application are described by applying specific examples. The above descriptions of the embodiments are only used to help understand the principles of the embodiments of the present application. Meanwhile, for the general skilled in the art, the specific implementation manners and application scopes will be changed according to the embodiments of the present application. In conclusion, the content of the present description should not be understood as a limitation of the present application.

Claims

1. A one-piece molding process for an electric engine assembly based on precision monolithic casting, characterized in that: The following steps are involved: Step S1: Using computer-aided design software to perform three-dimensional modeling, a precision monolithic casting mold with a split structure is designed. Each part of the precision monolithic casting mold is precisely positioned using high-precision locating pins and locating grooves. The precision monolithic casting mold is made of mold steel with high heat resistance, high wear resistance, and good thermal conductivity, and the surface of the precision monolithic casting mold is nitrided. Step S2: Selecting an aluminum alloy material with high strength, high thermal conductivity and good electromagnetic properties as a casting raw material, performing a quality inspection on the aluminum alloy raw material and cutting it into suitable sizes; Step S3, placing the aluminum alloy raw material into a vacuum induction melting furnace, melting it under argon protection, adding a refining agent after melting, and allowing it to stand after refining; Step S4: placing the precision casting mold in a preheating furnace for preheating, and spraying a special casting coating on the surface of the mold cavity after preheating; Step S5: slowly injecting the aluminum alloy liquid into the mold cavity at a pressure of 0.01-0.03 MPa using a low-pressure casting machine, controlling the filling speed to 10-20 cm / s, and maintaining the pressure at 0.01-0.03 MPa after filling; Step S6: Cooling the precision casting mold by combining air cooling and water cooling, and demolding after cooling is completed; Step S7, deburring, heat treating and surface treating the demoulded casting; Step S8: Conduct a comprehensive inspection on the casting, and assemble it with supporting parts after it passes the inspection.

2. The electric engine assembly integral molding process based on precision integral casting according to claim 1, characterized in that: The precision error of the precision casting mold does not exceed ±0.05mm, and the thickness of the nitride layer is controlled at 0.3-0.5mm.

3. The electric engine assembly integral molding process based on precision casting according to claim 1, characterized in that: The aluminum alloy material is 6061 aluminum alloy, wherein the iron content does not exceed 0.7% and the silicon content is between 0.4-0.8%.

4. The electric engine assembly integral molding process based on precision casting according to claim 1, characterized in that: In step S3, the smelting temperature is controlled at 720-750°C, the amount of refining agent added is 0.3-0.5% of the mass of the aluminum alloy raw material, the refining time is 10-15 minutes, and the standing time is 5-10 minutes.

5. The electric engine assembly integral molding process based on precision casting according to claim 1, characterized in that: The preheating temperature of the precision integral casting mold is controlled at 200-250°C, the preheating time is 1-2 hours, the casting coating adopts water-based coating, and the coating thickness is controlled at 0.1-0.3mm.

6. The electric engine assembly integral molding process based on precision integral casting according to claim 1, characterized in that: In step S5, the holding time is 3-5 minutes.

7. The electric engine assembly integral molding process based on precision integral casting according to claim 1, characterized in that: In step S6, the air cooling rate is controlled at 10-20°C / min, and the water cooling rate is controlled at 20-30°C / min, until the casting temperature drops to 100-150°C.

8. The electric engine assembly integral molding process based on precision integral casting according to claim 1, characterized in that: The heat treatment includes solution aging heat treatment, the solution treatment temperature is controlled at 520-540℃, the holding time is 2-3 hours, followed by water quenching, the quenching water temperature is controlled at 20-30℃, and after quenching, artificial aging treatment is performed, the aging temperature is controlled at 170-190℃, and the aging time is 6-8 hours.

9. The electric engine assembly integral molding process based on precision casting according to claim 1, characterized in that: Conformal cooling water channel design is introduced into the design of precision integral casting molds. The diameter of the cooling water channel is controlled at 3-5mm and the water flow speed is controlled at 0.5-1m / s.

10. The electric engine assembly integral molding process based on precision casting according to claim 1, characterized in that: Ultrasonic assisted melting technology is used in the aluminum alloy melting process. The ultrasonic frequency is 20-40kHz and the power is 1-3kW. During the low-pressure casting process, the pressure and temperature changes inside the mold cavity are monitored in real time, and the casting process is adjusted in real time according to the preset process parameters.