Core-free motor rotor packaging process

Abstract

The invention relates to the technical field of motor manufacturing, and discloses a coreless motor rotor packaging process, which comprises the following steps: shaping three coils into blocks by using a high-strength alloy steel clamp, arranging two shaping blocks back to back at intervals, loading into an aluminum machining part subjected to anodic oxidation treatment, the method comprises the following steps: firstly, performing injection molding, plating a hard chromium layer on a parting surface of a mold, performing dynamic balance correction on an I-shaped structure subjected to injection molding, finally performing stepped post-curing, and applying a 0.5-1T axial magnetic field in a cooling stage. A metal-injection molding material direct heat conduction path is established through the design of the T-shaped heat dissipation ribs in the inner cavity of the aluminum machining part and the heat conduction silicone grease coating, and the heat resistance is reduced by 61% in combination with the nanometer aluminum oxide filler epoxy resin. Axial magnetic field stepped curing inhibits thermal shrinkage deformation, the cracking rate of the rotor after thermal circulation is smaller than or equal to 5%, the temperature rise is reduced by 40 K compared with a traditional process, and then the structural reliability and the heat dissipation efficiency are improved.

Description

Technical Field

[0001] The present invention relates to the technical field of motor manufacturing, and in particular to a process for packaging a mover of an ironless motor. Background Art

[0002] The coreless motor mover packaging process involves the structural fixing, insulation protection, and heat management of the coil assembly of the moving component (motor) in a coreless motor. This process integrates the coil, heat dissipation structure, and package into a rigid whole, ensuring the motor's mechanical stability and electromagnetic performance at high speeds. It is primarily used in scenarios requiring high acceleration under light loads, extremely low bearing friction, and constant-speed motion at ultra-low speeds.

[0003] In traditional packaging processes, coil shaping and fixation usually adopts a multiple-step potting method. First, a single coil block is potted and shaped, then a back-to-back array is potted twice, the overall reinforcement is potted three times, and finally, the aluminum parts are installed and potted four times to form. The multiple potting process is complicated and requires multiple uses of potting equipment and fixtures, resulting in low production efficiency and high costs. Multiple potting can also easily introduce problems such as bubbles and uneven curing, affecting the packaging quality and reducing the reliability and performance of the product. Summary of the Invention

[0004] In response to the shortcomings of the existing technology, the present invention provides a coreless motor rotor packaging process, which solves the problem that traditional injection molding materials lack sufficient reinforcement structure and the packaging process has low heat dissipation efficiency, making it difficult to meet the mechanical strength and dimensional stability requirements of the coreless motor rotor.

[0005] To achieve the above objectives, the present invention is implemented through the following technical solutions:

[0006] A process for packaging a coreless motor rotor comprises the following steps:

[0007] S1. Coil shaping and fixing:

[0008] Use a high-strength alloy steel fixture to shape the three coils into blocks. The spacing between the fixture positioning blocks can be adjusted in the range of 5-15mm.

[0009] Infusing a two-component epoxy resin containing 15%-25% by mass of nano-alumina filler, the epoxy resin consists of component A and component B, wherein component A is bisphenol A epoxy resin and component B is a polyetheramine curing agent. The mixing ratio of component A to component B is 1:0.8-1:1.2, the viscosity is 100-500 Pa·s, the infusion amount is 10-20 grams, the temperature is 25-30°C, and the curing time is 20-40 minutes;

[0010] After curing, apply 50-100N preload for 2-5 minutes to eliminate internal stress;

[0011] S2. Coil assembly:

[0012] Arrange two shaping blocks back to back with a spacing of 1.5-3 mm, and install anodized aluminum machined parts. The anodized film thickness is 10-20 μm and the surface roughness is Ra0.4-0.8 μm.

[0013] The inner cavity of the aluminum machined part is provided with 3-5 groups of T-shaped heat dissipation ribs, the rib height is 2-4mm, the distance between adjacent ribs is 6-10mm, and the joint surface is coated with 0.1-0.3mm thermal conductive silicone grease;

[0014] S3, injection molding:

[0015] The mold parting surface is plated with hard chrome with a thickness of 0.05-0.08mm. The mold cavity size accuracy is ±0.1mm. Any of the following injection molding materials can be used:

[0016] PA66 and 30% glass fiber composite material;

[0017] Glass fiber reinforced modified plastics, wherein the glass fiber content is 10%-30% and the flame retardant content is 5%-15%;

[0018] The injection molding temperature is 120-140℃, the pressure is 80-120MPa, and three fan-shaped injection ports are symmetrically set on both sides of the mold. The width of each injection port is 3-5mm and the thickness is 0.8-1.2mm. The pressure is maintained for 15-20 seconds and the cooling rate is ≤8℃ / s.

[0019] S4, post-processing:

[0020] Dynamic balancing correction is performed on the I-shaped structure after injection molding at a speed of 2000-5000 rpm. The imbalance is removed by laser ablation, with a single removal amount of ≤0.05 grams.

[0021] Stepwise post-curing: in a nitrogen protection environment with O2≤200ppm, keep the temperature at 80℃ for 2 hours, then increase the temperature to 160℃ at a rate of 10℃ / h and keep the temperature for 4 hours. Apply 0.5-1T axial magnetic field during the cooling stage.

[0022] By adopting the above technical solution, a direct heat conduction path between metal and injection molding material is established through the design of T-shaped heat dissipation ribs in the inner cavity of the aluminum machined part and the application of thermal conductive silicone grease. Combined with nano-alumina filler epoxy resin, thermal resistance is reduced by 61%. Axial magnetic field step curing suppresses thermal shrinkage and deformation. The crack rate of the rotor after thermal cycling is ≤5%, and the temperature rise is reduced by 40K compared to traditional processes, thereby improving structural reliability and heat dissipation efficiency.

[0023] Preferably, the bottom of the aluminum machined part is provided with 7 screw holes, the positioning tolerance of the screw holes is ±0.05mm, and they cooperate with the mold positioning pins;

[0024] The hardware structure used to position the magnetic core has cavities on both sides to support the magnetic core, and the magnetic core is fixed with pre-tightening tooling to prevent injection molding deviation.

[0025] Preferably, a halogen-free flame retardant is added to the epoxy resin, and the mass fraction of the flame retardant is 6%-14%;

[0026] The wires connecting the coil electrodes are laser micro-welded with a welding power of 30-50W and a welding spot diameter of 0.3-0.6mm.

[0027] Preferably, the lead wires after laser micro-welding are coated with three layers of 250° C. resistant polyimide tape, and the thickness of each layer of tape is 15 μm-25 μm.

[0028] Preferably, the mold cooling system for injection molding uses multiple water channels with a channel spacing of 15-25 mm and a cooling water flow rate of 5-10 L / min;

[0029] The ejector pins of the mold are arranged in a combination of central symmetry and edge assistance. The ejector pins have a diameter of 5.0 mm and are 6 in number.

[0030] Preferably, there are 4-8 overflow grooves, the groove depth is 0.3-0.6 mm, and the angle between the groove body and the injection molding flow direction is 15-30 degrees.

[0031] Preferably, the assembly is preheated before injection molding in S3, with the preheating temperature being 80-120°C and the preheating time being 5-10 minutes; and at the same time, a high-frequency induction heating device is used to preheat the aluminum machined parts to 80-120°C.

[0032] Preferably, the wire used for the coil assembly connection is a 200°C resistant silver-plated copper wire, the outer layer of which is covered with a polytetrafluoroethylene insulation layer with a thickness of 0.1-0.3 mm.

[0033] Preferably, chopped carbon fiber reinforcement is added to the injection molding material, with a carbon fiber content of 10%-20% and a length of 0.2-0.8 mm, to form a composite reinforcement structure with the glass fiber;

[0034] The thickness of the rubber coating is 2.0-3.0mm, the product profile has a 1.0mm fillet, and the burr height of the parting line is ≤0.02mm.

[0035] Preferably, the coil shaping fixture in S1 and the injection molding mold in S3 are both manufactured using CNC machining technology with a machining accuracy of ±0.05 mm.

[0036] The present invention provides a process for packaging a coreless motor rotor. It has the following beneficial effects:

[0037] 1. This invention utilizes T-shaped heat dissipation ribs within the aluminum machined part and a coating of thermally conductive silicone grease to establish a direct heat conduction path between the metal and the injection molded material. Combined with nano-alumina filler epoxy resin, this reduces thermal resistance by 61%. Axial magnetic field step curing suppresses thermal shrinkage and deformation, resulting in a cracking rate of ≤5% after thermal cycling of the rotor. The temperature rise is reduced by 40K compared to conventional processes, thereby improving structural reliability and heat dissipation efficiency.

[0038] 2. The present invention forms metallurgical bonding solder joints through laser micro-welding, with a tensile strength of 85N. The three-layer polyimide tape coating maintains an insulation resistance of 10 at 250°C. 12 Ω, hardware positioning parts and ±0.05mm tolerance screw holes work together to control the core offset, injection molding preheating reduces thermal stress, and the coil assembly displacement is ≤0.05mm, thereby ensuring electrical safety and assembly accuracy.

[0039] 3. The present invention shortens the injection molding cycle to 65 seconds through the design of multiple cooling water channels and fan-shaped glue inlet. By forming a three-dimensional reinforced network with short-cut carbon fiber and glass fiber, the bending strength reaches 310MPa and the thermal expansion coefficient is reduced to 15×10 -6 / K, CNC machining accuracy of ±0.05mm ensures that the parting line burr is ≤0.02mm, thereby optimizing production efficiency and mechanical properties. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 The present invention is a flow chart of a coreless motor rotor packaging process. DETAILED DESCRIPTION

[0041] The following will clearly and completely describe the technical solution of the present invention in conjunction with the accompanying drawings. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0042] Please see the attached Figure 1 , an embodiment of the present invention provides a coreless motor mover packaging process, comprising the following steps:

[0043] S1. Coil shaping and fixing:

[0044] Use a high-strength alloy steel fixture to shape the three coils into blocks. The spacing between the fixture positioning blocks can be adjusted in the range of 5-15mm.

[0045] Infusing a two-component epoxy resin containing 15%-25% by mass of nano-alumina filler, the epoxy resin consists of component A and component B, wherein component A is bisphenol A epoxy resin and component B is a polyetheramine curing agent. The mixing ratio of component A to component B is 1:0.8-1:1.2, the viscosity is 100-500 Pa·s, the infusion amount is 10-20 grams, the temperature is 25-30°C, and the curing time is 20-40 minutes;

[0046] After curing, apply 50-100N preload for 2-5 minutes to eliminate internal stress;

[0047] S2. Coil assembly:

[0048] Arrange two shaping blocks back to back with a spacing of 1.5-3 mm, and install anodized aluminum machined parts. The anodized film thickness is 10-20 μm and the surface roughness is Ra0.4-0.8 μm.

[0049] The inner cavity of the aluminum machined part is equipped with 3-5 groups of T-shaped heat dissipation ribs, with a rib height of 2-4mm, a spacing of 6-10mm between adjacent ribs, and a 0.1-0.3mm thermal conductive silicone grease applied to the joint surface;

[0050] S3, injection molding:

[0051] The mold parting surface is plated with a hard chrome layer with a thickness of 0.05-0.08 mm. The mold cavity size accuracy is ±0.1 mm. The following injection molding materials are used:

[0052] PA66 and 30% glass fiber composite material;

[0053] Glass fiber reinforced modified plastics, wherein the glass fiber content is 10%-30% and the flame retardant content is 5%-15%;

[0054] The injection molding temperature is 120-140℃, the pressure is 80-120MPa, and three fan-shaped injection ports are symmetrically set on both sides of the mold. The width of each injection port is 3-5mm and the thickness is 0.8-1.2mm. The pressure is maintained for 15-20 seconds and the cooling rate is ≤8℃ / s.

[0055] S4, post-processing:

[0056] Dynamic balancing correction is performed on the I-shaped structure after injection molding at a speed of 2000-5000 rpm. The imbalance is removed by laser ablation, with a single removal amount of ≤0.05 grams.

[0057] Stepwise post-curing: in a nitrogen protection environment with O2≤200ppm, keep the temperature at 80℃ for 2 hours, then increase the temperature to 160℃ at a rate of 10℃ / h and keep the temperature for 4 hours. Apply 0.5-1T axial magnetic field during the cooling stage.

[0058] Please see the attached Figure 1 , there are 7 screw holes at the bottom of the aluminum machined part, and the screw hole positioning tolerance is ±0.05mm, which cooperates with the mold positioning pins;

[0059] The hardware structure used to position the magnetic core has cavities on both sides to support the magnetic core, and the magnetic core is fixed with pre-tightening tooling to prevent injection molding deviation.

[0060] Specifically, the precise screw hole positioning system provides a solid foundation for the entire assembly process. During the packaging process, the aluminum machined parts must be precisely aligned with the mold to ensure that each component is assembled in the correct position. The cavities on the left and right sides of the hardware structure are in close contact with the magnetic core, forming a solid support. This not only provides physical stability for the magnetic core during the injection molding process, but also, combined with the pre-loaded tooling, further enhances the core's fixation and effectively prevents the core from shifting under the high-temperature and high-pressure injection molding environment.

[0061] Please see the attached Figure 1 , halogen-free flame retardant is added to epoxy resin, and the mass fraction of flame retardant is 6%-14%;

[0062] The wires connecting the coil electrodes are laser micro-welded with a welding power of 30-50W and a welding spot diameter of 0.3-0.6mm.

[0063] Specifically, halogen-free flame retardants can function through a variety of flame-retardant mechanisms when encountering high temperatures or flames, such as endothermic decomposition, generation of fire-extinguishing gas, and formation of a heat-insulating carbon layer on the surface of the material, thereby effectively inhibiting the combustion process of the material, reducing the combustion rate and the speed of fire spread, and improving the flame retardant properties of the packaged product; and laser micro-welding has high energy density and precise welding characteristics, which can quickly generate high temperatures in a very small welding area, forming a strong metallurgical bond between the wire and the electrode, with high weld strength and low and stable contact resistance.

[0064] Please see the attached Figure 1 The lead wires after laser micro-welding are covered with three layers of 250℃ resistant polyimide tape, and the thickness of each layer of tape is 15μm-25μm.

[0065] Specifically, polyimide tape is an excellent insulating material with high insulation resistance and compressive strength. The three layers of polyimide tape wrapped around the lead wires can form an effective electrical insulation barrier to prevent accidental electrical contact between the wires and other components during use, avoid short-circuit failures, and ensure that current can be transmitted stably and safely, thereby protecting the normal operation and service life of the coreless motor.

[0066] Please see the attached Figure 1, the mold cooling system for injection molding uses multiple water channels with a channel spacing of 15-25mm and a cooling water flow rate of 5-10L / min;

[0067] The ejector pins of the mold are arranged in a combination of central symmetry and edge assistance. The ejector pins have a diameter of 5.0 mm and are 6 in number.

[0068] Specifically, by setting up multiple water channels in the mold, uniform cooling of different areas of the mold can be achieved. By controlling the cooling water flow, it can be ensured that the cooling water can remove the heat in the mold in a timely manner. At the same time, excessive pressure will not be generated due to excessive flow, which will affect the stability and service life of the mold. The combined layout of central symmetry and edge assistance can make the ejector pins evenly distributed in the mold, ensuring that the product is subjected to uniform ejection force during the demolding process, thereby improving demolding efficiency and product quality.

[0069] Please see the attached Figure 1 There are 4-8 overflow troughs with a depth of 0.3-0.6mm. The angle between the trough body and the injection flow direction is 15-30°.

[0070] Specifically, by properly setting the number, depth, and angle of the overflow troughs, air can be ensured to be discharged quickly and smoothly. A large number of overflow troughs increases the area and opportunity for exhaust. A moderate trough depth ensures sufficient space for air while preventing excessive melt intrusion and material waste due to excessive depth. The angle design conforms to the melt flow characteristics and helps guide the air to be discharged smoothly, thereby significantly reducing the probability of defects such as bubbles and silver streaks on the product surface and improving the product's appearance quality and mechanical properties. When the melt flows in the cavity, the overflow trough can temporarily accommodate excess melt, alleviating the flow imbalance problem caused by inconsistent flow speed at the front end of the melt.

[0071] Please see the attached Figure 1 Before S3 injection molding, the assembly is preheated at 80-120°C for 5-10 minutes. At the same time, a high-frequency induction heating device is used to preheat the aluminum machined parts at 80-120°C.

[0072] Specifically, preheating the assembly before S3 injection molding can increase the temperature of the plastic particles and reduce their viscosity, thereby improving the fluidity of the plastic melt. The improved fluidity makes it easier for the plastic melt to fill various parts of the mold cavity, especially for products with complex shapes and thin walls. It can effectively reduce defects such as short shots and material shortages, and improve the molding quality of the product. At the same time, the preheated assembly and aluminum machined parts make the mold temperature distribution more uniform, reducing the fluctuation of the mold temperature during the injection molding process.

[0073] Please see the attached Figure 1The wire used for coil assembly and connection is made of 200℃ resistant silver-plated copper wire, with an outer layer covered with polytetrafluoroethylene insulation layer with a thickness of 0.1-0.3mm.

[0074] Specifically, the copper wire has a temperature resistance of up to 200°C, which ensures that when the motor is running, even if high heat is generated, the wire can maintain stable performance, preventing damage to the wire or performance degradation due to overheating; the silver plating treatment further improves the high-temperature resistance and oxidation resistance of the copper wire, delaying the aging process of the wire in a high-temperature environment; the polytetrafluoroethylene insulation layer can provide excellent electrical insulation protection for the wire, effectively preventing short circuits between adjacent coils or wires, and ensuring the normal operation of the internal circuit of the motor. The material has excellent high-temperature resistance and can maintain stable insulation performance in a high-temperature environment. The insulation layer will not age or be damaged due to high temperature, further improving the reliability and safety of the motor under high-temperature operating conditions.

[0075] Please see the attached Figure 1 , add short-cut carbon fiber reinforcement to the injection molding material, with a carbon fiber content of 10%-20% and a length of 0.2-0.8mm, to form a composite reinforcement structure with glass fiber;

[0076] The thickness of the rubber coating is 2.0-3.0mm, the product profile has a 1.0mm fillet, and the burr height of the parting line is ≤0.02mm.

[0077] Specifically, the synergistic effect of chopped carbon fiber and glass fiber improves the strength and modulus of the injection molded material. Despite its short length, the chopped carbon fiber effectively transmits stress, forming a reinforcing phase within the material, sharing the load with the glass fiber, making the material more rigid and less susceptible to deformation when subjected to external forces. The rubber coating thickness is controlled at 2.0-3.0mm, achieving a balance between product protection and cost control. The rounded corner design ensures a more even distribution of stress when subjected to external forces, reducing stress concentration and the risk of cracking or damage during use, thereby improving the product's durability and reliability.

[0078] Please see the attached Figure 1 The coil shaping fixture in S1 and the injection molding mold in S3 are both manufactured using CNC machining technology with a machining accuracy of ±0.05mm.

[0079] Specifically, the high-precision fixtures and molds provide reliable guarantees for the entire packaging process, enabling processes such as coil shaping and injection molding to be carried out under stable process conditions. High-precision CNC machining enables key dimensions such as the positioning block spacing and shaping cavity shape of the coil shaping fixture to be accurately controlled, ensuring that the coil can be accurately shaped to the required shape and size; good mold surface quality and reasonable structural design help reduce mold wear and thermal stress concentration during the injection molding process, increase the service life of the mold, and reduce the frequency of mold maintenance and replacement.

[0080] Example 1: Basic process scheme

[0081] 1. Technical solution:

[0082] 1. Coil shaping: Use a high-strength alloy steel fixture with a spacing of 10 mm to fix three coils. Infuse 18 g of epoxy resin (A:B = 1:1, containing 20% ​​nano-alumina filler, viscosity 300 Pa·s) and cure at 30°C for 30 minutes. After curing, apply a preload of 80 N for 3 minutes.

[0083] 2. Coil assembly: Arrange two shaping blocks back to back with a spacing of 2mm, install anodized aluminum parts (film thickness 15μm, Ra0.6μm), set 4 groups of T-shaped heat dissipation ribs (rib height 3mm, spacing 8mm) in the inner cavity, and apply 0.2mm thermal conductive silicone grease on the joint surface.

[0084] 3. Injection molding: The mold is hard chrome plated with 0.06mm, PA66+30% glass fiber is selected, the injection temperature is 130℃, the pressure is 100MPa, there are 3 fan-shaped glue inlets (4mm wide, 1.0mm thick), the pressure is maintained for 18 seconds, and the cooling rate is 5℃ / s.

[0085] 4. Post-processing: dynamic balance correction (3000 rpm), laser ablation weight removal ≤ 0.04 g; step curing: 80℃ / 2h→160℃ / 4h (temperature increase 10℃ / h), apply 0.8T axial magnetic field during cooling.

[0086] 2. Verification test:

[0087] 1. Comparison Group 1: Traditional epoxy resin + no preload

[0088] (1) Preparation method:

[0089] (1) Preparation method:

[0090] Coil shaping: Use ordinary steel clamps (fixed spacing of 10 mm) to fix the coil, and pour 18 g of pure bisphenol A epoxy resin (A:B = 1:1, no filler, viscosity 450 Pa·s) and cure at 30°C for 30 minutes. Do not use the preload step.

[0091] (2) Coil assembly: The two shaping blocks are directly fitted (without gap) and loaded with non-anodized aluminum parts (surface Ra 1.2 μm). There are no heat dissipation ribs in the inner cavity, and the joint surface is coated with 0.2 mm ordinary silicone grease.

[0092] (3) Injection molding: ordinary mold (no coating), PA66 + 30% glass fiber, injection temperature 130 ° C, pressure 100 MPa, single point injection port (Φ5 mm), holding pressure 18 seconds, natural cooling (rate 15 ° C / s).

[0093] (4) Post-processing: After dynamic balance correction (3000 rpm), step curing and magnetic field treatment were cancelled.

[0094] Test items Example 1 Comparison group 1 Test standards Heat deformation temperature (℃) 215 180 GB / T1634.2-2019 Coil displacement (mm) 0.05 0.20 Vibration test ISO10816 Dynamic balance residual (g·mm) 0.8 2.5 ISO1940-1G2.5

[0095] 3. Summary: Nano-alumina filler improves thermal conductivity, preload eliminates internal stress, and increases thermal deformation temperature by 19.4%. Post-curing in the axial magnetic field reduces coil offset and improves dynamic balancing accuracy by 68%.

[0096] Example 2: Flame retardant optimization solution

[0097] 1. Technical solution:

[0098] Based on Example 1:

[0099] 1. Add 10% halogen-free flame retardant (phosphorus compound) to epoxy resin.

[0100] 2. The coil electrodes were laser micro-welded (power 40 W, solder joint diameter 0.45 mm), and the lead wires were coated with three layers of polyimide tape (single layer thickness 20 μm).

[0101] 3. Preheat the assembly to 100°C / 8 minutes before injection molding, and preheat the aluminum parts to 100°C by high-frequency induction.

[0102] 2. Verification test:

[0103] 1. Comparative group 2: no flame retardant + soldering

[0104] (1) Preparation method:

[0105] (1) No flame retardant was added to the epoxy resin, and the rest was the same as in Example 1.

[0106] (2) The coil electrodes are soldered (Sn63Pb37 solder, 380℃ soldering), and the lead wires are not coated with polyimide.

[0107] (3) Cancel preheating treatment and directly inject molding.

[0108] 2. Test standard: UL94 vertical burning test

[0109] project Example 2 Comparison group 2 Test standards Flame retardant grade V-0 HB UL94 vertical burning Tensile strength of solder joint (N) 85 52 IPC-TM-6502.4.1 Insulation resistance after aging at 250℃ for 100h <![CDATA[10 12 Oh]]> <![CDATA[10 9 Oh]]> GB / T1408.1-20163

[0110] 3. Summary: Phosphorus-based flame retardants work in tandem with nano-alumina to achieve V-0 flame retardancy; laser welding increases strength by 63% compared to soldering, and polyimide tape ensures high-temperature insulation stability.

[0111] Example 3: High-precision solution

[0112] 1. Technical solution:

[0113] Based on Example 2:

[0114] 1. The injection molding material is reinforced with 15% chopped carbon fiber (0.5mm long) + 25% glass fiber.

[0115] 2. The thickness of the rubber coating is 2.5mm, the contour radius is 1.0mm, and the burr of the parting line is ≤0.015mm.

[0116] 3. The mold cooling water channel spacing is 20mm, the flow rate is 8L / min; 6 ejector pins (Φ5.0mm) are arranged symmetrically.

[0117] 4. The CNC machining accuracy of fixture / mold is ±0.03mm.

[0118] 2. Verification test:

[0119] 1. Comparison group 3: Single glass fiber reinforcement + ordinary mold

[0120] (1) Preparation method:

[0121] (1) The injection molding material is changed to pure PA66 + 30% glass fiber (no carbon fiber).

[0122] (2) The mold cooling water channel spacing is 40 mm, the flow rate is 5 L / min; the ejector pins are asymmetrically arranged (4 6 mm diameter pins).

[0123] (3) The machining accuracy of fixture / mold is ±0.1mm.

[0124] (4) The contour has no rounded corners and the burr height of the parting line is 0.05mm.

[0125]

[0126] 3. Summary: Carbon / glass fiber composite reinforcement increases bending strength by 29% and reduces thermal expansion coefficient by 46%; high-precision molds and CNC machining ensure dimensional qualification rate > 99%.

[0127] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A process for packaging a coreless motor rotor, characterized by: The following steps are involved: S1. Coil shaping and fixing: Use a high-strength alloy steel fixture to shape the three coils into blocks. The spacing between the fixture positioning blocks can be adjusted in the range of 5-15mm. Infusing a two-component epoxy resin containing 15%-25% by mass of nano-alumina filler, the epoxy resin consisting of component A and component B, wherein component A is bisphenol A epoxy resin and component B is a polyetheramine curing agent. The mixing ratio of component A to component B is 1:0.8-1:1.2, the viscosity is 100-500 Pa·s, the infusion volume is 10-20 grams, the temperature is 25-30°C, and the curing time is 20-40 minutes; After curing, apply 50-100N preload for 2-5 minutes to eliminate internal stress; S2. Coil assembly: Arrange two shaping blocks back to back with a spacing of 1.5-3 mm, and install anodized aluminum machined parts. The anodized film thickness is 10-20 μm and the surface roughness is Ra0.4-0.8 μm. The inner cavity of the aluminum machined part is provided with 3-5 groups of T-shaped heat dissipation ribs, the rib height is 2-4mm, the distance between adjacent ribs is 6-10mm, and the joint surface is coated with 0.1-0.3mm thermal conductive silicone grease; S3, injection molding: The mold parting surface is plated with hard chrome with a thickness of 0.05-0.08mm. The mold cavity size accuracy is ±0.1mm. Any of the following injection molding materials can be used: PA66 and 30% glass fiber composite material; Glass fiber reinforced modified plastics, wherein the glass fiber content is 10%-30% and the flame retardant content is 5%-15%; The injection molding temperature is 120-140℃, the pressure is 80-120MPa, and three fan-shaped injection ports are symmetrically set on both sides of the mold. The width of each injection port is 3-5mm and the thickness is 0.8-1.2mm. The pressure is maintained for 15-20 seconds and the cooling rate is ≤8℃ / s. S4, post-processing: Dynamic balancing correction is performed on the I-shaped structure after injection molding at a speed of 2000-5000 rpm. The imbalance is removed by laser ablation, with a single removal amount of ≤0.05 grams. Stepwise post-curing: in a nitrogen protection environment with O2≤200ppm, keep the temperature at 80℃ for 2 hours, then increase the temperature to 160℃ at a rate of 10℃ / h and keep the temperature for 4 hours. Apply 0.5-1T axial magnetic field during the cooling stage.

2. The process for packaging a rotor of an ironless motor according to claim 1, characterized in that: The bottom of the aluminum machined part is provided with 7 screw holes, and the positioning tolerance of the screw holes is ±0.05mm, which cooperate with the mold positioning pins; The hardware structure used to position the magnetic core has cavities on both sides to support the magnetic core, and the magnetic core is fixed with pre-tightening tooling to prevent injection molding deviation.

3. The process for packaging a coreless motor rotor according to claim 1, characterized in that: A halogen-free flame retardant is added to the epoxy resin, and the mass fraction of the flame retardant is 6%-14%; The wires connecting the coil electrodes are laser micro-welded with a welding power of 30-50W and a welding spot diameter of 0.3-0.6mm.

4. The process for packaging a coreless motor rotor according to claim 3, characterized in that: The lead wires after laser micro-welding are coated with three layers of 250° C. resistant polyimide tape, and the thickness of each layer of tape is 15 μm-25 μm.

5. The process for packaging a coreless motor rotor according to claim 1, characterized in that: The mold cooling system for injection molding uses multiple water channels with a channel spacing of 15-25 mm and a cooling water flow rate of 5-10 L / min; The ejector pins of the mold are arranged in a combination of central symmetry and edge assistance. The ejector pins have a diameter of 5.0 mm and are 6 in number.

6. The process for packaging a rotor of an ironless motor according to claim 1, characterized in that: There are 4-8 overflow troughs with a depth of 0.3-0.6mm. The angle between the trough body and the injection flow direction is 15-30°.

7. The process for packaging a coreless motor rotor according to claim 1, characterized in that: Before S3 injection molding, the assembly is preheated at 80-120°C for 5-10 minutes. At the same time, a high-frequency induction heating device is used to preheat the aluminum machined parts at 80-120°C.

8. The process for packaging a coreless motor rotor according to claim 1, characterized in that: The wire material used for the coil assembly connection is a 200°C-resistant silver-plated copper wire, the outer layer of which is covered with a polytetrafluoroethylene insulation layer with a thickness of 0.1-0.3 mm.

9. The process for packaging a coreless motor rotor according to claim 1, characterized in that: The injection molding material is added with chopped carbon fiber reinforcement, with a carbon fiber content of 10%-20% and a length of 0.2-0.8 mm, to form a composite reinforcement structure with the glass fiber; The thickness of the rubber coating is 2.0-3.0mm, the product profile has a 1.0mm fillet, and the burr height of the parting line is ≤0.02mm.

10. The process for packaging a coreless motor rotor according to claim 1, characterized in that: The coil shaping fixture in S1 and the injection molding mold in S3 are both manufactured using CNC machining technology with a machining accuracy of ±0.05mm.

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