Motor stator-rotor core and method for manufacturing the insulation package thereof

Abstract

The application belongs to the technical field of motor manufacturing, and specifically discloses a motor stator-rotor core and an insulation packaging manufacturing method thereof. The motor stator-rotor core comprises a core body and a composite insulation anticorrosion coating wrapped on the surface of the core body; the composite insulation anticorrosion coating comprises an electrophoretic bottom layer and an insulation powder coating layer; the composite insulation anticorrosion coating is obtained by forming the electrophoretic bottom layer on the surface of the core body, processing the electrophoretic bottom layer into a semi-cured state, coating the insulation powder coating layer on the electrophoretic bottom layer in the semi-cured state, and then performing a curing treatment. The overall protection performance of the insulation coating of the motor core can be greatly improved by the application, and the problems of the traditional single oxidation / phosphating film, such as fragility, poor edge coverage of the organic coating, and extremely weak corrosion resistance, are solved.

Description

Technical Field

[0001] This application belongs to the field of motor manufacturing technology, specifically, it relates to a method for manufacturing a stator and rotor core of a motor and its insulating packaging. Background Technology

[0002] For high-efficiency and energy-saving generators (such as offshore wind turbines and range-extended generators), the stator and rotor cores are the core components of the magnetic circuit. To suppress eddy current losses generated by alternating magnetic fields inside the core, the core is typically made of thousands of thin silicon steel sheets (magnetically conductive plates) coated with insulating layers. The interlayer insulation performance of the core, especially the insulation integrity of the punched and sheared edges, directly determines the generator's efficiency and service life.

[0003] However, in existing motor core insulation manufacturing technologies, most motor cores use a single coating method, applying an oxide / phosphating film to the core surface. Although this coating is uniform and does not affect the stacking factor, it is brittle, has poor edge coverage, and extremely weak corrosion resistance, resulting in poor overall protective performance of the core coating. Especially in harsh environments with high salt spray and high humidity, such as offshore wind power, it is extremely prone to corrosion and failure.

[0004] Therefore, how to better achieve insulation manufacturing of motor cores has become a technical problem that the industry urgently needs to solve. Summary of the Invention

[0005] In view of the shortcomings of the existing technology, the purpose of this application is to better realize the insulation manufacturing of motor cores, and to solve the problem of poor overall protective performance of the existing motor core insulation coating.

[0006] To achieve the above objectives, in a first aspect, this application provides a motor stator and rotor core, comprising: The iron core body, and the composite insulating and anti-corrosion coating covering the surface of the iron core body; The composite insulating and anti-corrosion coating includes an electrophoretic underlayer and an insulating powder coating. The composite insulating and anti-corrosion coating is obtained by forming the electrophoretic underlayer on the surface of the iron core body, treating the electrophoretic underlayer to a semi-cured state, coating the insulating powder coating on the semi-cured electrophoretic underlayer, and then performing a curing process.

[0007] Optionally, the composite insulating and anti-corrosion coating further includes a surface conversion film layer, which is disposed between the iron core body and the electrophoretic substrate; the surface conversion film layer includes a nano-ceramic conversion film layer or a phosphating film layer.

[0008] Optionally, the thickness of the electrophoretic substrate ranges from 10 μm to 40 μm; the thickness of the insulating powder coating ranges from 30 μm to 100 μm; and the thickness of the composite insulating and anti-corrosion coating ranges from 40 μm to 120 μm.

[0009] Optionally, the insulating powder coating may be made of materials including but not limited to phenolic epoxy resin, modified polyester resin, or silicone resin-based powder coatings.

[0010] Optionally, the materials used for the electrophoretic substrate include, but are not limited to, modified epoxy resin, acrylic resin, or modified polyimide-based cathodic electrophoretic coatings.

[0011] Optionally, the core may include the stator core or rotor core of the target motor, which may include, but is not limited to, an automotive drive motor, a marine electric propulsion motor, or a compressor motor.

[0012] Secondly, this application provides an insulating encapsulation manufacturing method for preparing the stator and rotor cores of an electric motor as described above, comprising: The surface of the stacked iron core body is cleaned and treated with a conversion film to form a surface conversion film layer on the surface of the iron core body. Electrophoretic deposition is performed on the iron core body with a surface conversion film layer formed on its surface to obtain an iron core body with an electrophoretic underlayer formed on its surface; The iron core body with an electrophoretic underlayer formed on its surface is subjected to a semi-curing treatment to obtain an iron core body with an electrophoretic pre-cured layer formed on its surface that is not fully cross-linked; the electrophoretic pre-cured layer is an electrophoretic underlayer in a semi-cured state. An insulating powder coating is applied to the electrophoretic pre-cured layer to form a coating layer that resists the mechanical stress of the motor windings; The iron core body coated with the insulating powder coating is cured to obtain an iron core body with a composite insulating and anti-corrosion coating on the surface, thereby completing the preparation of the motor stator and rotor iron core.

[0013] Optionally, the electrophoretic deposition of the iron core body with a surface conversion film layer formed on its surface to obtain an iron core body with an electrophoretic underlayer formed on its surface includes: The iron core body with a surface conversion film layer formed on its surface is immersed in an electrophoresis tank containing a cathodic electrophoresis paint solution, and the temperature and pH value of the cathodic electrophoresis paint solution are controlled at a preset level. Using an iron core body with a surface conversion film layer formed on its surface as the cathode and a preset anode plate as the anode, a preset DC voltage is applied and maintained for a first preset time to obtain an iron core body with an electrophoretic underlayer formed on its surface.

[0014] Optionally, the process of semi-curing the iron core body on which the electrophoretic underlayer is formed on the surface to obtain an iron core body with a partially cross-linked electrophoretic pre-cured layer on the surface includes: The iron core body on which the electrophoretic layer is formed on the surface is preheated according to the second preset duration and the first preset temperature, so that the moisture in the electrophoretic layer can be fully evaporated. The preheated iron core body is heated according to the third preset time and the second preset temperature to obtain the iron core body with the electrophoretic pre-cured layer formed on the surface; the first preset temperature is not greater than the second preset temperature.

[0015] Optionally, the step of curing the iron core body coated with the insulating powder coating to obtain an iron core body with a composite insulating and anti-corrosion coating on its surface includes: The iron core body coated with the insulating powder coating is heated to the target curing temperature and maintained for a fourth preset time to allow the insulating powder coating to melt and flow, and to undergo a cross-linking reaction simultaneously with the lower electrophoretic pre-cured layer, thereby obtaining an iron core body with a composite insulating and anti-corrosion coating formed on its surface.

[0016] Overall, the technical solutions conceived in this application have the following beneficial effects compared with the prior art: This application provides a method for manufacturing an electric motor stator and rotor core and its insulation encapsulation. Through a cleverly designed step-by-step curing composite coating process, an integrated composite protective structure combining an electrophoretic underlayer and an insulating powder coating is constructed. This structure fully utilizes the conformal deposition characteristics of the electrophoretic coating along the geometric contour of the core, enabling precise and seamless coverage of the complex punched and sheared edges, burrs, and inner walls of the slots on the core body, effectively eliminating the risks of tip discharge and edge breakdown. At the same time, combined with the excellent leveling properties, mechanical strength, and chemical resistance of the outer insulating powder coating, a robust outer protective layer is provided for the core, capable of resisting external mechanical impacts, wear, and refrigerant corrosion. This greatly improves the overall protective performance of the electric motor core insulation coating and solves the problems of traditional single oxide / phosphating films being fragile, having poor edge coverage, and extremely weak corrosion resistance. Attached Figure Description

[0017] Figure 1 This is one of the structural schematic diagrams of the motor stator and rotor cores provided in the embodiments of this application; Figure 2 This is the second schematic diagram of the structure of the motor stator and rotor core provided in the embodiments of this application; Figure 3 This is one of the schematic flowcharts of the method for manufacturing the insulation packaging of the motor stator and rotor cores provided in the embodiments of this application; Figure 4 This is a second schematic flowchart of the method for manufacturing the insulation encapsulation of the motor stator and rotor cores provided in this application embodiment; Figure 5 This is a schematic diagram showing the results of pull-out force tests on the curved surfaces of a square stacked sample and a circular stacked sample provided in the embodiments of this application.

[0018] In all the accompanying drawings, the same reference numerals are used to denote the same elements or structures, wherein: 1 is the iron core body; 2 is the composite insulating and anti-corrosion coating; 21 is the electrophoretic underlayer; 22 is the insulating powder coating; 23 is the surface conversion film layer. Detailed Implementation

[0019] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0020] The terms "first" and "second," etc., used in the specification and claims of this application are used to distinguish different objects, not to describe a specific order of objects. For example, "first preset duration" and "second preset duration," etc., are used to distinguish different preset durations, not to describe a specific order of preset durations.

[0021] In the embodiments of this application, the terms "exemplary" or "for example" are used to indicate that something is an example, illustration, or description. Any embodiment or design that is described as "exemplary" or "for example" in the embodiments of this application should not be construed as being more preferred or advantageous than other embodiments or design. Specifically, the use of the terms "exemplary" or "for example" is intended to present the relevant concepts in a specific manner.

[0022] The embodiments of this application are described below with reference to the accompanying drawings.

[0023] Figure 1 This is one of the structural schematic diagrams of the motor stator and rotor cores provided in the embodiments of this application, such as... Figure 1 As shown, the stator and rotor cores of this motor include: The iron core body 1, and the composite insulating and anti-corrosion coating 2 covering the surface of the iron core body 1; The composite insulating and anti-corrosion coating 2 includes an electrophoretic substrate 21 and an insulating powder coating 22. The composite insulating and anti-corrosion coating 2 is obtained by forming an electrophoretic substrate 21 on the surface of the iron core body 1, treating the electrophoretic substrate 21 to a semi-cured state, coating the electrophoretic substrate 21 in the semi-cured state with an insulating powder coating 22, and then curing it.

[0024] Specifically, in the embodiments of this application, the core body is formed by stacking multiple magnetic conductive thin plates, the core body has a surface including punched edges and slot inner walls, and the surface of the core body is covered with an integrated composite insulating and anti-corrosion coating.

[0025] In the embodiments of this application, the magnetically conductive sheet can be made of non-oriented silicon steel sheet, with a preferred thickness of 0.15 mm to 0.25 mm. Non-oriented silicon steel sheet has isotropic magnetic properties, making it suitable for the stator and rotor cores of rotating electric machines. This thickness range effectively suppresses eddy current losses caused by alternating magnetic fields while ensuring sufficient mechanical strength, thereby improving motor efficiency.

[0026] One or both sides of the silicon steel sheets are pre-coated with an inorganic insulating layer (such as a phosphate-based or chromate-based coating), with a thickness of approximately 0.5 μm to 2 μm, to achieve electrical insulation between the silicon steel sheets and reduce interlayer eddy current losses in the core. Before lamination, the surface of the silicon steel sheets is also uniformly coated with a thermosetting adhesive (such as a phenolic resin or epoxy resin-based adhesive) to firmly bond the individual silicon steel sheets into a whole after lamination and curing.

[0027] In the embodiments of this application, the core body is a square or circular laminated body that is fixed by applying axial pressure in the lamination direction. Depending on the type of motor and application requirements, the core body can be manufactured using the following two structural forms.

[0028] The first method involves preparing a square laminate. Square laminations are stacked in a predetermined number, ensuring the insulation layer of each lamination is oriented in the same direction during stacking. After stacking to a predetermined thickness, high-strength metal clamps are used to radially tighten the laminate along the stacking direction, forming a structurally stable square laminated sample. The clamp material is preferably stainless steel or galvanized steel to prevent electrochemical corrosion during subsequent coating processes.

[0029] The second method involves preparing a circular laminate. After stacking circular laminations to a predetermined thickness, a stainless steel metal pressure plate is placed over each of the two end faces. Through interference fit or bolt connection, axial pressure is applied and locked in the stacking direction, forming a structurally stable circular laminate. This structure ensures the integrity of the core during subsequent coating processes and prevents lamination from disintegrating.

[0030] In embodiments of this application, the composite insulating and anti-corrosion coating includes an electrophoretic underlayer directly bonded to the surface of the iron core body, and an insulating powder coating compositely bonded to the electrophoretic underlayer. This insulating powder coating can be applied using electrostatic spraying, and therefore can also be described as an "electrostatic powder surface layer."

[0031] The electrophoretic underlayer is a dense film deposited conformally along the geometric contour of the iron core body. It has excellent conformability and edge coverage, covering the punched and sheared edges and inner walls of the slots of the iron core body, and can effectively wrap the sharp edges or burrs formed by punching and shearing silicon steel sheets. The insulating powder coating is a melt-cured leveling layer that covers the electrophoretic underlayer. The insulating powder coating is constructed to provide an outer protective layer that is resistant to mechanical impact and refrigerant corrosion. Furthermore, an integrated interface transition zone is formed between the electrophoretic underlayer and the insulating powder coating through in-situ co-curing. This interface transition zone has an interpenetrating polymer network (IPN) structure or chemical bond structure formed by the micro-diffusion of two layers of resin molecular chains, so that the resulting composite insulating and anti-corrosion coating has no layered interface on a macroscopic scale.

[0032] It should be noted that, regarding interface bonding and structural stability, this application embodiment achieves a super-strong bond between coatings through a unique in-situ co-curing technology. Unlike traditional physical layering, this application embodiment utilizes the residual active functional groups (such as hydroxyl or epoxy groups) in the semi-cured state of the electrophoretic substrate to chemically graft or cross-link with the resin of the insulating powder coating during high-temperature co-curing, thereby forming a composite insulating and anti-corrosion coating with an interpenetrating polymer network (IPN) structure or a chemically bonded structure with a gradient cross-linking density. This microscopic molecular chain diffusion and reaction results in a macroscopically layer-free composite coating, greatly enhancing interlayer adhesion. Experimental data show that even under extreme conditions of boiling water at 100°C for 60 hours, the coating still maintains a pull-out adhesion greater than 10 MPa, with no blistering, cracking, or peeling on the surface, demonstrating excellent resistance to damp heat aging and long-term operational reliability.

[0033] Based on the above structure, the composite insulating and anti-corrosion coating applied to the surface of the motor core provided in this application embodiment can achieve the following technical effects: Significantly improved adhesion and bonding strength: The electrophoretic underlayer forms excellent mechanical and chemical bonds with the substrate surface conversion layer, and the insulating powder top layer and the electrophoretic underlayer form chemical cross-links through the IPN structure, resulting in strong interlayer bonding. The composite insulating and anti-corrosion coating maintains a pull-out adhesion strength of greater than 10 MPa after 60 hours of boiling water aging test at 100℃; furthermore, the composite insulating and anti-corrosion coating showed no blistering, cracking, or peeling after the test.

[0034] Excellent coverage uniformity and edge protection: The electrophoretic substrate can cover all pores, grooves, gaps, and punching burrs without any blind spots. The powder layer provides a uniform and thick surface layer on the perfect electrophoretic substrate, with excellent edge wrapping and an edge coverage rate of over 99%.

[0035] Significantly improved corrosion resistance and protective lifespan: The electrophoretic underlayer greatly reduces the possibility of corrosion initiation in the substrate, while the insulating powder coating provides a thick physical barrier. The composite insulating anti-corrosion coating effectively protects against the erosion of refrigerants, lubricating oils, and salt spray environments.

[0036] Significantly improved electrical insulation performance: The double-layer insulation structure further enhances the breakdown voltage of the coating on the iron core surface. The dense double coating significantly reduces weak points in the insulation, greatly improving insulation reliability. The IPN interface structure eliminates electric field distortion at the delamination interface, improving resistance to partial discharge.

[0037] Safety Redundancy and Fault Tolerance: The composite double-coating technology provides significant safety redundancy for the motor's insulation and protection system. Even if the surface layer suffers minor damage, the underlying layer still provides reliable protection, preventing instantaneous catastrophic failure.

[0038] The stator and rotor cores of the motor in this embodiment utilize a cleverly designed step-by-step curing composite coating process to construct an integrated composite protective structure combining an electrophoretic underlayer and an insulating powder coating. This structure fully leverages the conformal deposition characteristics of the electrophoretic coating along the geometric contour of the core, enabling precise, seamless coverage of the core's complex punched and sheared edges, burrs, and slot inner walls, effectively eliminating the risks of tip discharge and edge breakdown. Simultaneously, combined with the excellent leveling properties, mechanical strength, and chemical resistance of the outer insulating powder coating, it provides the core with a robust outer protective layer capable of resisting external mechanical impacts, wear, and refrigerant corrosion. This significantly enhances the overall protective performance of the motor core's insulating coating, solving the problems of traditional single oxide / phosphating films being fragile, having poor edge coverage, and exhibiting extremely weak corrosion resistance.

[0039] Figure 2 This is a second schematic diagram of the structure of the motor stator and rotor core provided in the embodiments of this application, as shown below. Figure 2 As shown, based on the above embodiments, as an optional embodiment, the composite insulating and anti-corrosion coating 2 further includes a surface conversion film layer 23, which is disposed between the iron core body 1 and the electrophoretic substrate 21; the surface conversion film layer 23 includes a nano-ceramic conversion film layer or a phosphating film layer.

[0040] Specifically, in the embodiments of this application, the composite insulating and anti-corrosion coating further includes a surface conversion film layer disposed between the iron core body and the electrophoretic substrate. This surface conversion film layer can be formed by cleaning and converting the surface of the laminated iron core body. The surface conversion film layer includes a phosphating film layer or a nano-ceramic conversion film layer, which is configured to increase the micro-roughness of the iron core body surface to provide mechanical anchoring points for the electrophoretic substrate.

[0041] Alternatively, as an environmentally friendly alternative to phosphating, nano-ceramic conversion membranes can be generated on the iron core surface using silane or zirconium-based nano-ceramic conversion solutions, forming an amorphous conversion film with a thickness of approximately 20 nm to 200 nm. Nano-ceramic conversion membranes are free of heavy metals, simplify wastewater treatment, and also provide excellent coating adhesion.

[0042] Based on the above embodiments, as an optional embodiment, the thickness of the electrophoretic underlayer ranges from 10 μm to 40 μm; the thickness of the insulating powder coating ranges from 30 μm to 100 μm; and the thickness of the composite insulating and anti-corrosion coating ranges from 40 μm to 120 μm.

[0043] Specifically, in the embodiments of this application, the thickness of the electrophoretic underlayer can be controlled between 10μm and 40μm depending on the magnitude and time of the voltage applied between the anode and cathode; the thickness of the insulating powder coating can be controlled between 30μm and 100μm depending on the magnitude of the applied electric field and the time of powder spraying; and the total thickness of the composite insulating and anti-corrosion coating is controlled between 40μm and 120μm.

[0044] Optionally, in the embodiments of this application, the materials used for the electrophoretic substrate include, but are not limited to, modified epoxy resin, acrylic resin, or modified polyimide-based cathodic electrophoretic coating. That is, the electrophoretic substrate can be cured from modified epoxy resin, acrylic resin, or modified polyimide-based cathodic electrophoretic coating, and its heat resistance rating is not lower than 180°C.

[0045] In the embodiments of this application, the thickness of the electrophoretic substrate can be set to 10 μm to 40 μm, preferably 20 μm to 35 μm. The thickness deviation of the electrophoretic substrate at the punching edge is controlled within ±2 μm, ensuring complete coverage of complex geometric surfaces.

[0046] Here, the electrophoretic coating utilizes the large-scale deposition of colloidal particles onto the surface of a charged body under a direct current electric field to form a dense film. Cathodic electrophoresis is employed, using an iron core workpiece as the cathode. Positively charged coating colloidal particles migrate towards the cathode (workpiece) and deposit under the influence of an applied direct current electric field. The hydroxide ions generated in the cathode reaction do not dissolve the metal workpiece substrate, giving the coating excellent corrosion resistance. Simultaneously, the coating itself is pure and can perfectly protect the metal substrate.

[0047] Because electrophoresis technology has unparalleled coverage capabilities on complex workpiece surfaces, it can achieve seamless coating even on stator and rotor cores with complex slots, ventilation holes, and small internal holes, ensuring that every corner of the core, including punched and sheared burrs, slots, and internal holes, receives a uniform insulation layer. Especially on the sharp edges of the core laminations, the coating remains completely intact, effectively preventing edge-point discharge breakdown.

[0048] In the embodiments of this application, the insulating powder coating is a melt-cured leveling layer that covers the electrophoretic underlayer, and the insulating powder coating is configured to provide an outer protective layer that is resistant to mechanical shock and refrigerant corrosion.

[0049] Optionally, in the embodiments of this application, the materials used for the insulating powder coating include, but are not limited to, phenolic epoxy resin, modified polyester resin, or silicone resin-based powder coatings. That is, the insulating powder coating can be cured from phenolic epoxy resin, modified polyester resin, or silicone resin-based powder coatings, and its heat resistance rating is not lower than 180°C.

[0050] In the embodiments of this application, the thickness range of the insulating powder coating can be set to 30μm to 100μm, preferably 45μm to 80μm; while the total thickness of the composite insulating and anti-corrosion coating is 40μm to 120μm, preferably 60μm to 100μm.

[0051] Alternatively, the insulating powder coating can be applied via electrostatic spraying. Dry, micron-sized solid powder coating particles are charged with an electrostatic charge, and then the electrostatic field attracts these charged powder particles to the surface of a grounded iron core workpiece. Finally, heating melts, levels, and solidifies the powder, forming a hard, dense coating. The insulating powder coating exhibits excellent chemical resistance (resistance to refrigerants and lubricants), providing the motor iron core with higher mechanical strength, wear resistance, and optimal chemical resistance.

[0052] More importantly, an integrated interface transition zone can be formed between the electrophoretic substrate and the electrostatic powder surface layer through in-situ co-curing. The interface transition zone has an interpenetrating polymer network structure or chemical bond structure formed by the micro-diffusion of two layers of resin molecular chains, so that the composite insulating and anti-corrosion coating has no layered interface on a macroscopic scale.

[0053] It is important to note that the microstructure of this transition zone is characterized by the absence of a clear physical interface line between the electrophoretic substrate and the powder surface layer when observing the coating cross-section under an electron microscope. Instead, a transition zone with a thickness of approximately 2 μm to 5 μm exists. Within this transition zone, the electrophoretic resin phase and the insulating powder resin phase exhibit a gradient distribution of mutual penetration, confirming diffusion and cross-linking at the molecular chain level. Further observation of the ultrastructure of this transition zone using transmission electron microscopy reveals that the molecular chains of the two resins form an entangled network, rather than a simple interfacial contact.

[0054] More specifically, this interfacial bonding structure comprises a covalent network formed by the reaction of the active functional groups remaining in the semi-cured state of the electrophoretic substrate with the resin of the insulating powder coating at high temperature. Therefore, the resulting composite insulating and anti-corrosion coating has a gradient-varying crosslinking density, resulting in an interfacial bonding structure without obvious delamination.

[0055] It is important to clarify that the physical interpenetration in this application is not a simple rough surface interlocking, but rather refers to the diffusion and entanglement of molecular chains in a semi-cured state. In the pre-curing process of this application's embodiments, the electrophoretic substrate is controlled in a semi-cured state, with a curing conversion rate of approximately 60% to 80%. At this point, the electrophoretic coating has reached a touch-dry state to facilitate transfer and subsequent operations, but its molecular chain network still retains 20% to 40% of unreacted active functional groups, including hydroxyl (-OH), epoxy (-C2H3O), or carboxyl (-COOH) groups. These residual active groups are the material basis for subsequent chemical grafting with the powder coating.

[0056] Based on the above embodiments, as an optional embodiment, the iron core includes the stator iron core or rotor iron core of the target motor, and the target motor includes, but is not limited to, automobile drive motor, marine electric propulsion motor or compressor motor.

[0057] Specifically, regarding environmental adaptability and application areas, the motor stator and rotor cores provided in this application have a high heat resistance rating of H-class (180℃) or higher, enabling them to easily cope with the high temperature, high humidity, salt spray, and oil pollution environments faced by equipment such as new energy vehicle drive motors, marine electric propulsion motors, and fully enclosed compressor motors. The phosphating film or nano-ceramic conversion film formed in the pretreatment process further increases the micro-roughness of the substrate surface, providing mechanical anchoring points. Combined with the dual barrier effect of the composite coating, this can significantly improve the corrosion resistance life of the core under harsh working conditions and prevent the formation of corrosion initiation points on the substrate.

[0058] The following describes the method for manufacturing the insulation packaging of the motor stator and rotor core provided in this application. The method for manufacturing the insulation packaging of the motor stator and rotor core described below can be referred to in correspondence with the method for manufacturing the motor stator and rotor core described above.

[0059] Figure 3 This is a schematic flowchart of the method for manufacturing the insulation encapsulation of motor stator and rotor cores provided in this application embodiment. It can be understood that this method can be applied to the preparation of any of the aforementioned motor stator and rotor cores, such as... Figure 3 As shown, the method includes: Step S1: Clean and apply a conversion film to the surface of the stacked iron core body to form a surface conversion film layer on the surface of the iron core body. Step S2: Electrophoretic deposition is performed on the iron core body with a surface conversion film layer formed on the surface to obtain an iron core body with an electrophoretic underlayer formed on the surface. Step S3: The iron core body with an electrophoretic underlayer formed on its surface is subjected to a semi-curing treatment to obtain an iron core body with an electrophoretic pre-cured layer formed on its surface that is not fully cross-linked; the electrophoretic pre-cured layer is an electrophoretic underlayer in a semi-cured state. Step S4: Apply an insulating powder coating to the electrophoretic pre-cured layer to form a coating layer for resisting mechanical stress on the motor windings; Step S5 involves curing the iron core body coated with insulating powder coating to obtain an iron core body with a composite insulating and anti-corrosion coating on the surface, thereby completing the preparation of the motor stator and rotor iron core.

[0060] Specifically, the surface conversion film described in the embodiments of this application refers to a thin film of metal compound formed on the surface of the iron core metal through chemical or electrochemical treatment. It may specifically include a nano-ceramic conversion film or a phosphating film, used to increase the microscopic roughness of the iron core body surface to provide mechanical anchoring points for subsequent electrophoretic undercoating.

[0061] More specifically, in the embodiments of this application, in step S1, a stacked iron core body is provided, and the surface of the stacked iron core body is cleaned and treated with a conversion film. A surface conversion film layer, such as a phosphating film or a nano-ceramic conversion film, is formed on the surface of the iron core body to establish micro-anchoring points.

[0062] It should be noted that in this embodiment of the application, coating treatment is carried out after the iron core body is stacked and formed, which can effectively avoid damage to the coating during the stacking process and further improve the protective performance of the subsequent coating.

[0063] In the embodiments of this application, in step S2, electrophoretic deposition is performed on the iron core body on which a surface conversion film layer is formed. Specifically, the iron core body can be used as the cathode for electrophoretic deposition to form a conformal electrophoretic wet film covering the punching edge and the inner wall of the slot of the iron core body, and the electric field edge effect is used to preferentially wrap the punching burrs, thereby obtaining an iron core body with an electrophoretic bottom layer formed on the surface.

[0064] In the embodiments of this application, in step S3, the iron core body on which the electrophoretic underlayer is formed on the surface is subjected to a semi-curing treatment, converting the electrophoretic underlayer into a semi-cured state, and forming an electrophoretic pre-cured layer with incomplete surface cross-linking by controlling the degree of curing. This is a key control step for achieving interface integration in this application.

[0065] Furthermore, in the embodiments of this application, in step S4, the pre-cured iron core workpiece can be grounded to the ground by electrostatic spraying through a hanger, with the workpiece as the positive electrode, and an insulating powder coating can be applied to the electrophoretic pre-cured layer to form a coating layer for resisting the mechanical stress of the motor winding.

[0066] Furthermore, in the embodiments of this application, in step S5, the iron core body coated with insulating powder coating is heated to a preset final curing temperature for curing treatment, so that the insulating powder coating melts and flows smoothly, and induces the insulating powder coating and its underlying electrophoretic pre-cured layer to undergo a cross-linking reaction simultaneously, forming an integrated insulating encapsulation structure, thereby obtaining an iron core body with a composite insulating and anti-corrosion coating on the surface, and completing the preparation of the motor stator and rotor iron core.

[0067] The motor stator and rotor core insulation encapsulation manufacturing method provided in this invention has excellent process controllability. By precisely controlling the semi-curing degree of the electrophoretic wet film and the final co-curing temperature, it achieves synchronous cross-linking between the electrophoretic underlayer and the insulating powder surface layer. This process not only utilizes the edge effect of the electric field to preferentially wrap the most vulnerable stamping burrs, but also eliminates stress concentration and defects inside the coating through one-step high-temperature melting and leveling, ensuring the integrity and consistency of the insulation structure. It is particularly suitable for high-end motor manufacturing with extremely high requirements for product quality consistency.

[0068] Figure 4 This is a second schematic flowchart of the method for manufacturing the insulation packaging of the motor stator and rotor cores provided in this application embodiment, as shown below. Figure 4 As shown in the embodiments of this application, the method mainly includes three major processes: a pretreatment process, an electrophoretic coating process, and an electrostatic powder coating process. For the pretreatment process, the iron core body is provided and its surface is pretreated. The purpose of this process is to create suitable conditions for a firm bond between the composite coating and the surface of the motor stator and rotor iron core, establishing microscopic anchoring points.

[0069] More specifically, the first step is to provide a laminated core body. Here, non-oriented silicon steel sheets with a thickness ranging from 0.15 mm to 0.25 mm can be selected as the base material; this specification is a commonly used material for motor stator and rotor cores. One side of the silicon steel sheet has a pre-formed inorganic insulating layer, and thermosetting adhesive is uniformly coated between the sheets.

[0070] The aforementioned silicon steel sheets are stamped into specific shapes and stacked in a predetermined quantity. During stacking, it is ensured that the insulation layer of each stamped sheet is aligned, and pressure is applied along the stacking direction to stack the silicon steel sheets.

[0071] Optionally, for square stacked samples, after the square stampings are stacked to a predetermined thickness, high-strength metal clamps are used to radially tighten the stacked body along the stacking direction, thereby forming a structurally stable square stacked sample, effectively preventing the sheets from scattering during subsequent coating, curing and handling.

[0072] Optionally, for circular stacked samples, after stacking the circular stampings to a predetermined thickness, a stainless steel metal pressure plate is placed on each of its two end faces. Through interference fit, axial pressure is applied and locked in the stacking direction to form a structurally stable circular stacked sample, ensuring its integrity in subsequent coating processes.

[0073] Furthermore, the surface of the iron core body, including the punched and sheared burrs, undergoes degreasing and washing. Using a heated alkaline degreasing agent (50°C to 70°C) via spraying or immersion, grease, stamping oil, and dirt are thoroughly removed from the surface of the iron core body. If the sample surface is heavily soiled, it can be performed in two steps: pre-degreasing followed by main degreasing. After degreasing, multiple washes are performed to remove any remaining degreasing agent.

[0074] Furthermore, the cleaned iron core body undergoes surface conversion treatment, including phosphating or nano-ceramic conversion treatment, to form a phosphating film or nano-ceramic conversion film.

[0075] The phosphating process includes: using a zinc-based or manganese-based phosphating solution to form a uniform, microporous, water-insoluble crystallization conversion film with a thickness of approximately 1 μm to 5 μm on the surface of the iron core. The phosphating temperature is 35℃ to 55℃, and the treatment time is 3 min to 10 min. The phosphating film can significantly increase the surface area of ​​the substrate, providing a strong mechanical anchoring and chemical bonding effect for subsequent electrophoretic coating.

[0076] The nano-ceramic conversion process includes: using a silane or zirconium-based nano-ceramic conversion solution to generate an amorphous conversion film with a thickness of approximately 20 nm to 200 nm on the iron core surface. The processing temperature is from room temperature to 50°C, and the processing time is from 1 min to 5 min. The nano-ceramic conversion film is free of heavy metals and has good environmental friendliness.

[0077] Furthermore, after the surface conversion treatment, multiple water washes and drying processes are required to ultimately obtain the iron core body with a surface conversion film. The final water wash step must use deionized water to prevent the iron core workpiece from introducing impurity ions that contaminate the subsequent electrophoresis bath. Here, the conductivity of the deionized water should be controlled below 20 μS / cm.

[0078] This process involves degreasing and surface conversion treatment, which establishes a uniform, microporous anchoring point structure on the surface of the iron core. The surface conversion film greatly increases the surface area, providing a physical anchoring foundation and chemical bonding sites for the subsequent electrophoretic substrate, which is the basic guarantee for achieving high adhesion.

[0079] Based on the above embodiments, as an optional embodiment, step S2, performing electrophoretic deposition on the iron core body with a surface conversion film layer formed on its surface to obtain an iron core body with an electrophoretic underlayer formed on its surface, includes: The iron core body with a surface conversion film layer formed on its surface is immersed in an electrophoresis tank containing a cathodic electrophoresis paint solution, and the temperature and pH value of the cathodic electrophoresis paint solution are controlled at a preset level. Using an iron core body with a surface conversion film layer formed on its surface as the cathode and a preset anode plate as the anode, a preset DC voltage is applied and maintained for a first preset time to obtain an iron core body with an electrophoretic underlayer formed on its surface.

[0080] It should be noted that the punched and sheared edges of the motor stator and rotor cores are weak points in insulation protection. During the punching and shearing process, burrs and microcracks will be generated on the edges of the silicon steel sheets. These defective areas are prone to causing electric field concentration effects when the motor is running, leading to an increased risk of partial discharge, and in severe cases, insulation breakdown.

[0081] Specifically, in this embodiment, the conformal coating of the electrophoretic underlayer provides an ideal substrate for the subsequent electrostatic powder topcoat. The powder topcoat forms a continuous, molten, and leveled film on the smoothed surface of the electrophoretic underlayer, further enhancing the mechanical protection of the edge areas. This dual-layer structure can counteract the electric field concentration effect at the stator core edges, effectively preventing partial discharge under high-frequency pulse voltages and significantly improving the voltage withstand rating of the coating.

[0082] More specifically, such as Figure 4 As shown, step S2 is used to perform electrophoretic deposition in the electrophoretic coating process. Specifically, after the treatment in step S1, the iron core workpiece with the surface conversion film layer can be immersed in an electrophoresis tank containing a cathodic electrophoretic paint solution. The temperature of the cathodic electrophoretic paint solution is controlled between 28°C and 32°C, and the pH value is controlled at a preset weakly acidic level, such as between 5.8 and 6.5, to provide an ideal physical environment for the electric field edge effect in the subsequent electrophoretic deposition process. The cathodic electrophoretic paint in the cathodic electrophoretic paint solution is preferably a modified epoxy resin-based or acrylic resin-based water-based electrophoretic paint; epoxy resin-based electrophoretic paint has excellent adhesion and corrosion resistance, and is suitable for occasions with extremely high protection requirements; acrylic resin-based electrophoretic paint has better weather resistance and flexibility, and is suitable for occasions with appearance requirements; the solid content of the electrophoretic paint can be set to 15% to 25%.

[0083] Furthermore, using the workpiece as the cathode (-) and the anode plate as the anode (+), a preset DC voltage is applied and maintained for a first preset electrophoresis time. Specifically, a DC voltage of 100V to 500V can be applied, and the electrophoresis time is 60s to 300s. In this way, the positively charged paint resin particles in the cathodic electrophoresis paint solution move towards the cathode and deposit under the influence of the electric field. An electrolytic reaction occurs on the cathode surface, generating hydroxide ions (OH-). - This process raises the local pH value, causing resin particles to become unstable and deposit on the workpiece surface, forming a dense, uniform electrophoretic wet film, resulting in the iron core body with an electrophoretic underlayer on the surface. Here, because the hydroxide ions generated in the cathodic reaction do not dissolve the metal workpiece substrate, the coating exhibits excellent corrosion resistance.

[0084] In this embodiment, the cathodic electrophoresis technology employs unique conformal deposition characteristics, preferentially encapsulating punch burrs by utilizing the edge effect of the electric field. During electrophoresis, the electric field lines have a higher density at the tips and edges, resulting in a higher deposition rate of coating particles at punched edges and burr areas compared to flat surfaces. This "tip enhancement effect" allows the electrophoretic underlayer to achieve conformal coverage along the geometric contour of the core body, completely encapsulating the burrs at the punched edges. The coating thickness tolerance can be controlled within ±2μm, ensuring the consistency of the core magnetic circuit and production efficiency.

[0085] Furthermore, after cathodic electrophoresis, the workpiece can be rinsed with the permeate from an ultrafiltration water washing system to recover any paint residue that is adhering to the surface of the electrophoretic wet film but not fully solidified. Material utilization can reach over 95%, while maintaining the stability of the bath solution. The workpiece is then rinsed with deionized water to ensure the coating surface is clean and free of any impurities.

[0086] The method of this application embodiment achieves full utilization of cathodic electrophoretic deposition and electric field edge effect by setting the thermodynamic and chemical properties of the electrophoretic bath solution. It achieves conformal coverage without dead angles on the entire surface of the iron core body, including complex grooves, ventilation holes, small inner holes, punching and shearing burrs, and inner walls of the groove opening. This makes the electrophoretic wet film dense and uniform, and the edge thickness deviation can be controlled within ±2μm, laying an excellent foundation for subsequent coating processes.

[0087] Based on the above embodiments, as an optional embodiment, step S3 involves performing a semi-curing treatment on the iron core body with an electrophoretic underlayer formed on its surface to obtain an iron core body with a partially cross-linked electrophoretic pre-cured layer on its surface, including: The iron core body on which the electrophoretic layer is formed is preheated according to the second preset duration and the first preset temperature so that the moisture in the electrophoretic layer can be fully evaporated. The preheated iron core body is heated according to the third preset time and the second preset temperature to obtain an iron core body with an electrophoretic pre-cured layer on the surface; the first preset temperature is not greater than the second preset temperature.

[0088] Specifically, in the embodiments of this application, such as Figure 4 As shown, step S3 is used to perform the semi-curing process in the electrophoretic coating process. Specifically, the workpiece washed after electrophoresis, i.e., the iron core body with the electrophoretic underlayer formed on the surface, is sent to a curing oven for preliminary pre-curing treatment. First, preheating treatment is performed at a first preset temperature, such as 60°C to 120°C, to allow sufficient evaporation of moisture in the electrophoretic coating. The second preset time can be set to 10 min to 20 min. Then, the temperature is raised to the second preset temperature, which can be set to 120°C to 185°C, and maintained for a third preset time, which can be set to 10 min to 30 min, to allow the electrophoretic wet film to undergo a pre-crosslinking reaction. During this process, the resin and curing agent in the electrophoretic coating film undergo a crosslinking reaction, transforming from a linear structure to a dense three-dimensional network structure, thereby obtaining excellent hardness, adhesion, corrosion resistance, and insulation.

[0089] It should be noted that the preset duration and preset temperature mentioned above can be determined based on the curing characteristics of the electrophoretic coating and verified by experimental data.

[0090] It should also be noted that the curing temperature at this time should be set below the starting temperature of the complete cross-linking reaction of the electrophoretic wet film. The pre-curing treatment is controlled to ensure that the degree of curing (curing conversion rate) of the electrophoretic layer reaches 60% to 80%, i.e., in stage B.

[0091] Under the aforementioned pre-curing conditions, the electrophoretic pre-cured layer has dried to facilitate transfer and subsequent operations, but its molecular chain network still retains 20% to 40% of unreacted active functional groups. These active functional groups include hydroxyl (-OH), epoxy (-C2H3O), or carboxyl (-COOH) groups. These residual active groups are the material basis for subsequent chemical grafting with the powder coating and are a key prerequisite for achieving the IPN interface structure.

[0092] In the embodiments of this application, the surface curing degree of the electrophoretic pre-cured layer can be inspected using differential scanning calorimetry (DSC) or gel fraction testing. During DSC testing, the residual heat of reaction of the pre-cured sample and the fully cured sample are compared to calculate the curing conversion rate. During gel fraction testing, an uncrosslinked component is extracted using a suitable solvent, and the degree of crosslinking is calculated based on the mass change.

[0093] The method in this application embodiment, by precisely controlling the semi-curing process parameters, retains 20% to 40% of the active functional groups in the electrophoretic pre-cured layer. These active functional groups can be used to chemically react with the powder coating during the subsequent co-curing process to form an IPN interface structure, thereby achieving the integrated fusion of the two coating layers.

[0094] It should be noted that this is the core difference between this application and the existing technology of "complete curing followed by powder coating".

[0095] Furthermore, continue to refer to Figure 4 In the embodiments of this application, step S4 is used to perform electrostatic powder spraying in the electrostatic powder coating process. More specifically, the pre-cured workpiece is grounded by connecting it to the ground via a hanger, with the workpiece serving as the positive electrode. Using a corona spray gun, the insulating powder coating particles are given a negative charge (the voltage can be set from -30kV to -90kV, preferably from -50kV to -70kV). According to the principle of attraction between opposite charges, the negatively charged powder particles are attracted at high speed to the surface of the workpiece under the action of an electrostatic field, and are firmly adsorbed onto the surface of the electrophoretic pre-cured layer by electrostatic force. As the adsorbed powder layer thickens, the newly arrived charged powder will be repelled by the same charge of the already deposited powder layer. When the repulsive force and the electrostatic attraction force are balanced, the powder is difficult to continue to be adsorbed, which allows the coating thickness to automatically tend to be uniform and not to increase indefinitely.

[0096] Here, the insulating powder coating is preferably a thermosetting powder coating based on phenolic epoxy resin, modified polyester resin, or silicone resin, with a heat resistance rating of not less than 180℃. Among them, the phenolic epoxy system has excellent chemical resistance and electrical insulation properties, and is suitable for applications requiring refrigerant resistance, such as compressor motors; the modified polyester system has good mechanical properties and weather resistance, and is suitable for industrial motors and applications with aesthetic requirements; the silicone resin system has the highest heat resistance rating (up to 200℃ or above), and is suitable for H-class high-temperature motors.

[0097] Optionally, in the embodiments of this application, the particle size distribution of the insulating powder coating is 20 μm to 80 μm, preferably 30 μm to 50 μm, to obtain optimal leveling and edge coverage.

[0098] In addition, powder that is not adsorbed onto the workpiece surface can be collected, sieved, and reused by the recycling system, achieving a material utilization rate of over 99%. Recycled powder is mixed with new powder in a specific ratio to ensure the stability of the coating quality.

[0099] In this embodiment, a uniform powder coating is formed on the electrophoretic pre-cured layer by electrostatic spraying. After curing, the powder coating will become an outer protective layer that resists the mechanical stress of the motor winding (such as friction and scratching during the winding process), while also providing protection against mechanical impact and refrigerant corrosion.

[0100] Based on the above embodiments, as an optional embodiment, step S5, which involves curing the iron core body coated with insulating powder coating to obtain an iron core body with a composite insulating and anti-corrosion coating formed on its surface, includes: The iron core body coated with insulating powder coating is heated to the target curing temperature and maintained for a fourth preset time to allow the insulating powder coating to melt and flow, and to undergo a cross-linking reaction simultaneously with the lower electrophoretic pre-cured layer to form an integrated composite insulating and anti-corrosion coating, thus obtaining an iron core body with a composite insulating and anti-corrosion coating on its surface.

[0101] Specifically, in the embodiments of this application, such as Figure 4 As shown, step S5 is used to perform the co-curing film formation process in the electrostatic powder coating process. Specifically, the iron core body workpiece with the insulating powder coating is sent to a curing oven for heating and curing, the temperature is raised to the target curing temperature, which is the complete curing temperature of the electrophoretic coating, and maintained for a fourth preset time. Here, the target curing temperature can be specifically set to 160℃ to 200℃, and the fourth preset time can be specifically set to 15min to 30min. Preferably, the target curing temperature is set to 175℃ to 185℃, and the fourth preset time is set to 18min to 25min.

[0102] Understandably, the target curing temperature and the fourth preset time can be determined based on the curing characteristics of the electrophoretic coating and verified by experimental data.

[0103] At the final curing temperature, the insulating powder particles first melt and fuse together to form a continuous liquid film, leveling and covering the entire surface of the iron core workpiece. Subsequently, during continuous heating, the insulating powder coating and the electrophoretic pre-cured layer undergo a cross-linking curing reaction simultaneously. At the target curing temperature, the molten powder resin molecular chains are fluid, capable of penetrating into the surface region of the electrophoretic pre-cured layer (penetration depth approximately 0.5 μm to 3 μm), and undergoing chemical grafting or cross-linking reactions with the retained active functional groups, thereby constructing an interfacial transition zone with a gradient cross-linking density between the two layers. The active functional groups in the powder resin (such as epoxy, hydroxyl, or isocyanate groups) form a covalent bond network with the active functional groups retained in the electrophoretic layer, causing the two coatings to fuse into one at the molecular level. Finally, after cooling, an integrated composite insulating and anti-corrosion coating is formed on the iron core body.

[0104] It should be noted that this in-situ co-curing process forms an interfacial transition region with an interpenetrating polymer network (IPN) structure. This interfacial transition region has a gradient crosslinking density, so that the composite insulating and anti-corrosion coating has no obvious delamination interface on a macroscopic scale.

[0105] The method in this application, through the introduction of a stepwise co-curing process, allows the insulating powder coating to melt and flow, simultaneously cross-linking with the electrophoretic pre-cured layer to form an integrated insulating encapsulation structure. The insulating powder coating undergoes internal cross-linking and curing, forming an IPN structure with the electrophoretic coating interface, resulting in a macroscopically seamless composite whole. This is the core process feature that distinguishes this application from existing technologies and is crucial for achieving excellent adhesion and long-term reliability.

[0106] Compared with existing surface oxidation treatment technology, organic coating technology, and other technologies, the insulating encapsulation manufacturing method of this application has the following significant advantages: First, it exhibits stronger adhesion and bonding. The electrophoretic underlayer forms excellent mechanical and chemical bonds with the substrate surface conversion layer, and the powder top layer and electrophoretic underlayer form IPN chemical cross-links through co-curing, resulting in strong interlayer bonding. Compared to a single surface oxide layer or organic coating, adhesion is improved by more than 80%.

[0107] Secondly, it offers superior coverage uniformity and edge protection. The electrophoretic underlayer can cover all internal holes, grooves, and gaps without any blind spots, and preferentially wraps the burrs on the die using the edge effect of the electric field. The powder layer provides a uniform and thick surface layer on the perfect electrophoretic underlayer, with an edge coverage rate of over 99%.

[0108] Third, corrosion resistance and protective lifespan are significantly improved. The electrophoretic underlayer greatly reduces the possibility of corrosion initiation in the substrate, while the powder layer provides a thick physical barrier. This dual barrier effectively prevents corrosion from refrigerants, lubricants, and salt spray environments.

[0109] Fourth, electrical insulation performance is significantly improved. The double-layer insulation structure further increases the breakdown voltage of the coating. The dense double coating significantly reduces weak points in the insulation, greatly improving insulation reliability. The IPN interface structure eliminates the risk of interface delamination.

[0110] Fifth, safety redundancy and fault tolerance. The composite double-coating technology ensures that the motor stator and rotor cores receive double, uniform, and robust protection from their most complex internal structures to their sharp edges, eliminating any potential local weaknesses that could lead to early failure. Even if the surface layer suffers minor damage, the underlying layer still provides reliable protection.

[0111] To verify the effectiveness of the motor stator and rotor core insulation encapsulation manufacturing process provided in this application, three specific embodiments using different resin systems are given below. It should be noted that regardless of the resin system combination used for the electrophoretic underlayer and the insulating powder coating, the core process concept of "utilizing the active functional groups in the semi-cured state of the underlayer to achieve double-layer co-curing" is followed.

[0112] Example 1 This embodiment prepares a stator core suitable for drive motors in new energy vehicles. It employs an epoxy composite coating system combining an epoxy electrophoretic underlayer and a phenolic epoxy powder top layer, emphasizing high adhesion and oil resistance. The process parameters for Example 1 are shown in Table 1.

[0113] Table 1

[0114] Coating characteristics of Example 1: Scanning electron microscopy revealed a 3 μm thick transition zone between the electrophoretic underlayer and the powder surface layer. The two resin phases exhibited a gradient distribution of mutual penetration, confirming diffusion and cross-linking at the molecular chain level, forming a typical IPN interface structure. The coating thickness deviation at the punched edge was controlled within ±1.5 μm, with complete edge coverage and no leaks, achieving an edge coverage rate of 99.5%. The coating achieved a heat resistance rating of H (180℃), suitable for high-temperature, high-oil environments in oil-cooled drive motors.

[0115] Example 2 This embodiment prepares an acrylic-polyester composite coating suitable for auxiliary motor systems in new energy vehicles (such as electric air conditioning compressor motors and electronic water pump motors). It employs an acrylic electrophoretic underlayer combined with a modified polyester powder top layer, emphasizing the coating's economic efficiency and good appearance. The process parameters for Example 2 are shown in Table 2.

[0116] Table 2

[0117] The coating characteristics of Example 2: The coating surface has high gloss and a smooth appearance. The acrylic underlayer and polyester toplayer are connected by ester bonds formed through the reaction of hydroxyl and carboxyl groups, resulting in good interfacial adhesion. The use of a nano-ceramic conversion film instead of a phosphate film improves the environmental friendliness of the process. The coating exhibits excellent weather resistance, with an edge coverage rate of 99.2%.

[0118] Example 3 This embodiment prepares stator and rotor cores suitable for high-temperature motors (such as H-class 200℃ motors and marine propulsion motors). It employs a composite coating system using a polyimide-modified electrophoretic underlayer and an organosilicon powder top layer, emphasizing the coating's high-temperature resistance. The process parameters for Example 3 are shown in Table 3.

[0119] Table 3

[0120] The coating characteristics of Example 3: The coating exhibits excellent high-temperature resistance, capable of operating continuously at 200℃, and meets the requirements of Class H insulation. Both the polyimide-modified epoxy underlayer and the silicone toplayer possess a Si-O-Si framework structure, exhibiting good chemical compatibility and high thermal stability. The relatively large coating thickness provides enhanced mechanical protection and salt spray resistance. It is suitable for high-temperature, high-salt-spray applications such as marine propulsion motors and aerospace motors. Edge coverage reaches 99.6%.

[0121] To demonstrate the inventive advantages of the "semi-curing + co-curing" process in this application compared with existing technologies, the following two sets of comparative examples are set up for comparative analysis.

[0122] Comparative Example 1 This comparative example simulates the common "fully cured before powder coating" process in the prior art, where the electrophoretic layer is fully cured (curing degree ≥ 98%), then the surface is roughened by sanding, and finally a powder coating is applied. This process is similar to traditional automotive repair painting processes, and contrasts with the semi-curing co-curing process of this application. The process parameters of Comparative Example 1 are shown in Table 4.

[0123] Table 4

[0124] Analysis of coating characteristics and defects in Comparative Example 1: Since the electrophoretic layer is fully cured (curing degree ≥ 98%), its molecular chain network contains almost no active functional groups, and it can only form physical adhesion and van der Waals force bonding with the powder coating. Observation of the coating cross-section under an electron microscope reveals a clear physical interface line between the electrophoretic underlayer and the powder surface layer, with no IPN penetration transition zone. This interface structure is prone to delamination failure along the interface when subjected to thermal shock, mechanical stress, or media penetration.

[0125] Comparative Example 2 This comparative example simulates the existing technology that uses only a single-layer electrostatic powder coating process, i.e., directly spraying powder coating onto the surface of the phosphated iron core without setting an electrophoretic underlayer. This process is the current standard practice for insulation treatment of some motor iron cores. The process parameters for Comparative Example 2 are shown in Table 5.

[0126] Table 5

[0127] Analysis of coating characteristics and defects in Comparative Example 2: While the single-layer powder coating exhibits good coverage on flat surfaces, uneven coverage exists in complex geometric areas such as punching / shearing edges and the inner walls of slots. Due to the leveling properties of powder coatings, the coating thickness is significantly reduced at sharp edges (thickness deviation can reach ±15μm or more), creating weak points in insulation. The edge coverage rate is only about 85% to 92%, far lower than the 99% or more achieved in this application. In punching / shearing burr areas, the single-layer powder coating cannot achieve complete coverage, posing a risk of incomplete coating. These areas are prone to partial discharge during motor operation.

[0128] To comprehensively evaluate the performance of the composite insulating and anti-corrosion coating of this application, the following tests were performed on the square and circular laminated samples prepared in Examples 1-3 and Comparative Examples 1-2.

[0129] Pull-out adhesion test: Strictly in accordance with GB / T 5210-2006 "Paints and Varnishes - Pull-out Adhesion Test" and GB / T 31586.1-2015 "Evaluation and Acceptance Criteria for Adhesion / Cohesion (Breaking Strength) of Protective Coating Systems for Corrosion Protection of Steel Structures". Customized pull-out spindles are used to ensure test accuracy: For square stacked samples, flat-bottomed pull-out spindles are used to test the coating adhesion on the stacked plane; for circular stacked samples, arc-bottomed pull-out spindles are used. The radius of curvature of these spindles is precisely designed to match the test arc surface of the circular sample to ensure uniform stress distribution and reliable results during testing.

[0130] Here, the selection criteria for the pull-out force test surfaces are as follows: a flat surface (square sample) and an arc surface (circular sample) formed by the stacking direction of silicon steel sheets are selected as the test surfaces. This stacked surface is not a single, complete metal surface, but a composite interface composed of the silicon steel sheet substrate, its surface inorganic insulating layer, and the inter-sheet thermosetting adhesive layer, exhibiting microscopic inhomogeneities and potential weak points. Performing pull-out force tests on this type of composite interface can more realistically simulate the coating adhesion environment of an actual iron core, imposing more stringent requirements on the coating's bonding strength.

[0131] High-temperature water boiling aging test: The coated sample is completely immersed in boiling water at 100℃ for continuous boiling. This environment can simulate the extreme working conditions of high temperature and high humidity, accelerating the aging of the coating and the penetration of the medium. After boiling for the preset time (1h, 12h, 24h, 36h, 48h, 60h), the sample is immediately removed from the water bath and a pull-out force test (hot pull-out test) is quickly performed while the coating is still hot, and the changes in the surface morphology of the coating are observed at the same time.

[0132] Edge coverage test: The coating coverage of the punched edge was observed using a scanning electron microscope, and the percentage of the edge with complete coverage was counted to the total edge length.

[0133] Refrigerant immersion test (for compressor motors): The sample was immersed in a mixture of R134a refrigerant and refrigeration oil (volume ratio 7:3) at 70°C for 240 hours. After immersion, the sample was removed, the appearance of the coating was observed, and the pull-out adhesion was tested.

[0134] ATF oil immersion test (for oil-cooled drive motors): The sample is immersed in automatic transmission fluid (ATF oil) at 120°C for 500 hours. After immersion, the coating appearance changes are observed and the pull-out adhesion is tested.

[0135] In the embodiments of this application, the performance comparison data of the above embodiments 1-3 and comparative examples 1-2 are shown in Table 6.

[0136] Table 6

[0137] Detailed data on the change of hot pull-out force with boiling time in this embodiment, as well as the hot pull-out force test results of the square and round samples in Example 1, are shown in Table 7 (unit: MPa).

[0138] Table 7

[0139] The test conditions defined in the table above are as follows: Cold state refers to the test being performed directly after the composite double coating has been prepared and cooled to room temperature (approximately 25°C); Hot state (1h, 12h, 24h, 36h, 48h, 60h) refers to the test being performed quickly while the sample is still in a high-temperature state after being continuously boiled in a 100°C water bath for the corresponding duration.

[0140] like Figure 5 As shown in a specific embodiment of this application, test data indicates that the composite insulating and anti-corrosion coating of Embodiment 1 exhibits excellent initial adhesion in a cold state. The peak vertical pull-out forces of the square sample plane (i.e., a double-coated square with a total thickness of 100 μm) and the circular sample arc surface (i.e., a double-coated arc surface with a total thickness of 100 μm) reach 34.18 MPa and 26.71 MPa, respectively. With the extension of the boiling time at 100°C, the pull-out force gradually decreases, which is a normal performance degradation under harsh high temperature and high humidity conditions.

[0141] Even after 60 hours of continuous boiling, the pull-out forces of the square and rounded surfaces remained at 13.69 MPa and 12.92 MPa respectively, both significantly higher than the acceptance threshold of 10 MPa. This result fully demonstrates that the composite double coating can maintain excellent adhesion after long-term extreme humid heat aging, meeting the stringent requirements of high-performance motors for the long-term reliability of the insulating coating.

[0142] Simultaneous observation of the coating morphology showed that no failure phenomena such as bubbles, cracks, wrinkles, or peeling appeared on the surface of the hot samples after boiling for different durations (1 h to 60 h). This indicates that the composite dual-coating system has excellent integrity and stable resistance to damp heat aging, and its physical and chemical structure remains intact under accelerated aging conditions.

[0143] Based on the comparison of the above test data, the following clear conclusions can be drawn, proving the inventiveness of this application relative to the prior art: The fundamental difference in interface bonding methods: The "semi-curing + co-curing" process used in this application's embodiment creates an IPN interface transition zone with a gradient cross-linking density between the electrophoretic substrate and the insulating powder surface layer, while the "full curing + post-spraying" process used in Comparative Example 1 only forms a physical interface bond. This fundamental difference results in the initial pull-out force of this application's embodiment (34.2 MPa) being approximately 84% higher than that of Comparative Example 1 (18.6 MPa).

[0144] Significant advantages in long-term durability: After 60 hours of high-temperature boiling aging, the pull-out force retention rate of Example 1 of this application was 40% (decreasing from 34.2 MPa to 13.7 MPa), while the retention rate of Comparative Example 1 was only 28% (decreasing from 18.6 MPa to 5.3 MPa). More importantly, the pull-out force of the Example 1 after aging was still significantly higher than 10 MPa and the coating appearance remained unchanged, while Comparative Example 1 showed slight blistering, indicating that its interface had begun to fail.

[0145] A decisive improvement in edge protection: This application achieves an edge coverage rate of over 99% by utilizing the conformal deposition characteristics of the electrophoretic substrate and the edge effect of the electric field, while the edge coverage rate of the single-layer powder coating in Comparative Example 2 is only about 88%. The edge thickness deviation is reduced from ±15μm in Comparative Example 2 to ±2μm in this application. This is of decisive significance for the insulation reliability of the motor core, because weak points at the edges are often the starting point of insulation failure and partial discharge.

[0146] Significantly improved resistance to media erosion: In the tests of resistance to refrigerant (240h) and ATF oil (500h), the performance degradation of the embodiments of this application was significantly less than that of the comparative example. This is due to the IPN interface structure preventing media molecules from penetrating along the interface path, demonstrating the synergistic protective effect of the composite coating, where "1+1>2". This performance is particularly important for compressor motors and oil-cooled drive motors.

[0147] It should be understood that any content not described in detail in this specification is prior art known to those skilled in the art.

[0148] It should also be understood that expressions such as “comprising” and “may include” used in this application indicate the existence of the disclosed functions, operations, or constituent elements, and do not limit one or more additional functions, operations, and constituent elements. In this application, terms such as “comprising” and / or “having” are to be interpreted as indicating a particular characteristic, number, operation, constituent element, component, or combination thereof, but not to exclude the existence or possibility of adding one or more other characteristics, numbers, operations, constituent elements, components, or combinations thereof.

[0149] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A stator and rotor core for an electric motor, characterized in that, include: The iron core body, and the composite insulating and anti-corrosion coating covering the surface of the iron core body; The composite insulating and anti-corrosion coating includes an electrophoretic underlayer and an insulating powder coating. The composite insulating and anti-corrosion coating is obtained by forming the electrophoretic underlayer on the surface of the iron core body, treating the electrophoretic underlayer to a semi-cured state, coating the insulating powder coating on the semi-cured electrophoretic underlayer, and then curing it.

2. The motor stator and rotor core according to claim 1, characterized in that, The composite insulating and anti-corrosion coating also includes a surface conversion film layer, which is disposed between the iron core body and the electrophoretic substrate; the surface conversion film layer includes a nano-ceramic conversion film layer or a phosphating film layer.

3. The motor stator and rotor core according to claim 1, characterized in that, The thickness of the electrophoretic underlayer ranges from 10 μm to 40 μm; the thickness of the insulating powder coating ranges from 30 μm to 100 μm; and the thickness of the composite insulating and anti-corrosion coating ranges from 40 μm to 120 μm.

4. The motor stator and rotor core according to claim 1, characterized in that, The insulating powder coating uses materials including, but not limited to, phenolic epoxy resin, modified polyester resin, or silicone resin-based powder coatings.

5. The motor stator and rotor core according to claim 1, characterized in that, The materials used for the electrophoretic substrate include, but are not limited to, modified epoxy resin, acrylic resin, or modified polyimide-based cathodic electrophoretic coatings.

6. The motor stator and rotor core according to any one of claims 1-5, characterized in that, Includes the stator core or rotor core of the target motor, which includes, but is not limited to, automotive drive motors, marine electric propulsion motors, or compressor motors.

7. A method for manufacturing an insulating package for preparing the stator and rotor core of an electric motor as described in any one of claims 1-6, characterized in that, include: The surface of the stacked iron core body is cleaned and treated with a conversion film to form a surface conversion film layer on the surface of the iron core body. Electrophoretic deposition is performed on the iron core body on which a surface conversion film layer is formed to obtain an iron core body on which an electrophoretic underlayer is formed. The iron core body with an electrophoretic underlayer formed on its surface is subjected to a semi-curing treatment to obtain an iron core body with an electrophoretic pre-cured layer formed on its surface that is not fully cross-linked; the electrophoretic pre-cured layer is an electrophoretic underlayer in a semi-cured state. An insulating powder coating is applied to the electrophoretic pre-cured layer to form a coating layer that resists the mechanical stress of the motor windings; The iron core body coated with the insulating powder coating is cured to obtain an iron core body with a composite insulating and anti-corrosion coating on the surface, thereby completing the preparation of the motor stator and rotor iron core.

8. The method for manufacturing the insulating encapsulation of the motor stator and rotor core according to claim 7, characterized in that, The process of electrophoretically depositing a surface conversion film layer on the iron core body to obtain an electrophoretically coated bottom layer on the surface includes: The iron core body with the surface conversion film layer formed on its surface is immersed in an electrophoresis tank containing a cathodic electrophoresis paint solution, and the temperature and pH value of the cathodic electrophoresis paint solution are controlled at a preset level. Using the iron core body with the surface conversion film layer formed on the surface as the cathode and the preset anode plate as the anode, a preset DC voltage is applied and maintained for a first preset time to obtain an iron core body with an electrophoretic underlayer formed on the surface.

9. The method for manufacturing the insulating encapsulation of the motor stator and rotor cores according to claim 7, characterized in that, The process of semi-curing the iron core body with an electrophoretic underlayer formed on its surface to obtain an iron core body with a partially cross-linked electrophoretic pre-cured layer on its surface includes: The iron core body on which the electrophoretic layer is formed on the surface is preheated according to the second preset duration and the first preset temperature, so that the moisture in the electrophoretic layer can be fully evaporated. The preheated iron core body is heated according to the third preset time and the second preset temperature to obtain the iron core body with the electrophoretic pre-cured layer formed on the surface; the first preset temperature is not greater than the second preset temperature.

10. The method for manufacturing the insulating encapsulation of the motor stator and rotor core according to claim 7, characterized in that, The process of curing the iron core body coated with the insulating powder coating to obtain an iron core body with a composite insulating and anti-corrosion coating on its surface includes: The iron core body coated with the insulating powder coating is heated to the target curing temperature and maintained for a fourth preset time to allow the insulating powder coating to melt and flow, and to undergo a cross-linking reaction simultaneously with the lower electrophoretic pre-cured layer, thereby obtaining an iron core body with a composite insulating and anti-corrosion coating formed on its surface.

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