An outer-wound inner-outer double-groove frameless torque motor stator and a manufacturing method thereof

Abstract

This invention discloses an externally wound frameless torque motor stator with internal and external double slots and its manufacturing method. The stator includes an annular stator core composed of multiple stator units evenly arranged along the circumference. Each stator unit includes a shoe portion, a tooth portion, and an independent yoke portion. The shoe portion is located radially inner, and adjacent shoe portions are connected by a connecting portion to form an annular pole shoe. The tooth portion is located on the outer side of the shoe portion and extends radially outward. The independent yoke portion is located at the outer end of the tooth portion, and each independent yoke portion is separated from each other circumferentially to form an outer slot that extends radially to the tooth portion. A reserved slot is opened on the wall of the connecting portion facing the tooth slot, and its width is equal to the width of the semi-closed slot required for the finished product. The manufacturing method includes: stacking and forming the stator core, winding wire from the outside through the outer slot using an external winding machine, potting and curing, and boring the inner hole to remove the connecting portion to form a semi-closed slot. This invention reduces costs and improves production efficiency while retaining the excellent magnetic properties of the semi-closed slot.

Description

Technical Field

[0001] This invention relates to the field of motor manufacturing technology, specifically to an externally wound frameless torque motor stator with internal and external double slots and its manufacturing method. Background Technology

[0002] Frameless torque motors eliminate the need for a complete housing, independent bearings, and output shafts. Only the stator and rotor are supplied separately, requiring embedding within the equipment body. Direct drive is achieved using the equipment's own frame and bearings. The core requirements are low-speed, high-torque output, high torque output stability, and high-precision closed-loop control. To improve torque density, suppress localized magnetic saturation in the teeth, and reduce stator iron losses, mainstream stators in the industry adopt a semi-closed slot structure: the narrow slot openings constrain air gap magnetic permeability fluctuations in the stator teeth, reducing cogging torque and lowering low-speed vibration and electromagnetic noise.

[0003] However, existing semi-closed slot stators suffer from a core bottleneck in the winding process. The extremely narrow inner slot opening prevents the wire nozzle of conventional automatic winding machines from reaching inside the slots to complete the winding arrangement, necessitating manual winding and unwinding. Manual winding is time-consuming, results in poor winding consistency, easily damages inter-turn insulation, and extremely low mass production efficiency. Furthermore, the large variation in the number of turns and coil tightness leads to significant performance differences between batches of motors. Simply widening the inner slot opening to accommodate automatic winding would exacerbate air gap magnetic harmonics, drastically worsening cogging torque and vibration noise, thus negating the core advantages of the quiet and stable operation of semi-closed slot stators. In addition, as in the Chinese patent CN121566803A, which uses a split yoke and toothed assembly, and a method of first potting glue and then boring to form an open slot, the coil needs to be pre-wound and shaped. Then, the pre-shaped coil pins need to be manually cut and the paint removed. The coil is then manually fitted into the toothed part and the yoke is embedded into the outer periphery of the toothed part. Afterward, workers need to shape the pins of each coil and then solder the pins to the hub PCB board. These processes cannot be automated. There are too many manual processes that workers need to participate in, and the operation is cumbersome and complicated, which limits the production efficiency. In addition, the hub PCB board is added, and the material and labor costs are high. Summary of the Invention

[0004] In view of this, the present invention addresses the deficiencies of the existing technology, and its main objective is to provide an externally wound frameless torque motor stator with inner and outer double slots and its manufacturing method. The aim is to achieve automatic mechanized winding of the stator while retaining the excellent magnetic properties of the inner semi-closed slots, replacing manual winding, reducing manual processes, improving production efficiency and winding consistency, and reducing costs.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] A frameless torque motor stator includes an annular stator core, wherein the stator core is composed of a plurality of identical stator units uniformly arranged along the circumferential direction, and a single stator unit includes:

[0007] The boot portion is located radially inside the stator core. The boot portions of adjacent stator units are connected by a connecting portion, and all the boot portions together form an annular pole shoe.

[0008] The teeth are located on the radially outer side of the boot portion and extend radially outward;

[0009] An independent yoke is provided at the radial outer end of the tooth; the independent yokes of each stator unit are separated from each other circumferentially, and an outer groove is formed between two adjacent independent yokes that extends radially into the tooth;

[0010] A reserved groove is provided on the wall surface of the connecting part facing the tooth groove. The reserved groove extends through the stator core along the axial direction. The width of the reserved groove is equal to the groove width of the semi-closed groove required for the finished motor stator.

[0011] As a preferred embodiment, the outer contour of the independent yoke is an arc surface, and the arc outer peripheral surfaces of each independent yoke are spliced ​​together to form a complete cylindrical assembly surface.

[0012] As a preferred embodiment, each of the stator units is formed by stacking stator laminations axially, and the shoe portion, the connecting portion, the tooth portion, and the independent yoke portion are integrally stamped from the same stator lamination.

[0013] As a preferred embodiment, the reserved groove is exposed after the connecting part is boring away, forming the opening of the semi-closed groove.

[0014] The present invention also provides a method for manufacturing the stator of a frameless torque motor, comprising the following steps:

[0015] S100. Stator laminations are stacked and formed into an annular stator core. The stator core includes multiple identical stator units. Each stator unit has a shoe portion, a connecting portion, a tooth portion, and an independent yoke portion. The shoe portions of adjacent stator units are connected by the connecting portion, and an outer groove is formed between adjacent independent yoke portions.

[0016] S200. Using an automatic external winding machine, the wire tip passes through the outer slot from the radial outside of the stator core and winds the coil on the outside of the teeth.

[0017] S300. The stator core with the coil wound on it is potted and cured so that the coil and the stator core are cured into one piece;

[0018] S400. The inner hole of the stator core after potting and curing is bored to remove at least a portion of the connecting part, so that a semi-closed groove is formed between adjacent shoe parts.

[0019] As a preferred embodiment, in step S100, the stator lamination is formed by stamping silicon steel material in one piece, and the shoe portion, the connecting portion, the tooth portion and the independent yoke portion are formed on the same stator lamination.

[0020] As a preferred embodiment, step S200 includes:

[0021] S210. The stacked stator core is coaxially fixed to the automatic external winding machine fixture, so that the outer slot faces the wire nozzle side of the winding machine.

[0022] S220. The winding machine nozzle passes through the outer slot from the radial outside of the stator core and extends into the winding area outside the tooth, continuously winding the coil according to the preset number of turns and layers.

[0023] S230. After the winding is completed, the coil is shaped and the leads are welded.

[0024] As a preferred embodiment, step S300 includes:

[0025] S310. Install glue-filling fixtures at both ends of the stator core along the axial direction to form a sealed glue-filling cavity;

[0026] S320. Inject liquid potting compound into the sealed potting cavity to fill the gaps and tooth grooves of the coil.

[0027] S330. Vacuuming and heating the sealed potting cavity to achieve initial degassing, including: first performing vacuuming and heating to achieve initial degassing, then adding glue and performing vacuuming and heating to achieve deep degassing and high-temperature curing.

[0028] As a preferred embodiment, the vacuum degree of the initial degassing is 0.01MPa to 0.08MPa, the temperature is 80℃ to 120℃, and the holding time is 5min to 20min; the vacuum degree of the deep degassing and high-temperature curing is 0.01MPa to 0.08MPa, the temperature is 80℃ to 120℃, and the duration is 2h to 8h; and before injecting the liquid potting compound, the stator core, the potting compound, and the potting fixture are preheated to 60℃ to 80℃.

[0029] As a preferred embodiment, in step S400, the boring process includes a rough boring process and a finish boring process:

[0030] S410, the rough boring process removes the main metal of the connecting part, leaving a finishing allowance of 0.2mm to 0.5mm on one side;

[0031] S420, The precision boring process removes all the reserved allowance, causing the adjacent boot parts to separate from each other in the circumferential direction, and the reserved groove is fully exposed to form the semi-closed groove;

[0032] Furthermore, during boring, the coaxiality error between the outer circle of the stator core and the boring machine spindle is controlled within 0.02mm.

[0033] Compared with the prior art, the present invention has significant advantages and beneficial effects. Specifically, as can be seen from the above technical solution, it mainly has the following beneficial effects:

[0034] 1. This invention, by setting mutually separated independent yokes, forms an outer slot between adjacent independent yokes that extends to the teeth. The wire nozzle of the automatic external winding machine can pass through the outer slot from the outside of the stator without interference and enter the winding area of ​​the teeth to complete the winding. The open outer slot completely avoids the winding interference problem of the traditional inner semi-closed slot, eliminating the need for manual wire threading or unwinding, significantly increasing the winding speed of the winding, greatly reducing manual operation procedures, operation difficulty, and labor time, and reducing labor costs. At the same time, it eliminates the need for a hub PCB board, further reducing material costs and making it suitable for mass production.

[0035] 2. This invention adopts a combination of stator lamination integral molding, automated winding and boring pre-made slot structure. The reserved slot width of the connection part is guaranteed by the lamination accuracy and is not affected by boring machining error. Automated winding eliminates the turn error and uneven coil tension caused by manual winding. The dispersion of electromagnetic parameters such as tooth cogging torque and back electromotive force of motors in the same batch is significantly reduced, improving product consistency and greatly improving product yield.

[0036] 3. This invention employs a sequential process of "first winding and potting, then boring to form the semi-closed slot." During the winding and potting stages, the connecting parts maintain the connection between the shoe parts, ensuring the core remains a complete annular rigid whole, providing a stable winding skeleton for automated winding. After the connecting parts are removed during the boring stage, the pre-reserved slot is exposed to form a standard semi-closed slot opening, improving the overall mechanical strength and reliability of the stator. This process sequence fundamentally resolves the contradiction between "narrow slot openings cannot be automatically wound" and "wide slot openings have high cogging torque," achieving automated production while retaining the excellent magnetic properties of low cogging torque and low noise of the semi-closed slot.

[0037] To more clearly illustrate the structural features and effects of the present invention, the present invention will be described in detail below with reference to the accompanying drawings and specific embodiments. Attached Figure Description

[0038] To more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. The drawings described below are merely exemplary, and those skilled in the art can derive other embodiments based on the provided drawings without creative effort.

[0039] Figure 1 This is a schematic diagram of the stator core structure according to an embodiment of the present invention;

[0040] Figure 2 This is a schematic diagram of the stator structure after winding, according to an embodiment of the present invention;

[0041] Figure 3 This is a cross-sectional view of the stator structure after winding, according to an embodiment of the present invention.

[0042] Figure 4 This is a schematic diagram of the stator structure after glue application according to an embodiment of the present invention;

[0043] Figure 5 This is a cross-sectional view of the stator structure after glue application, according to an embodiment of the present invention.

[0044] Figure 6 This is a schematic diagram of the stator structure after boring according to an embodiment of the present invention;

[0045] Figure 7 This is a cross-sectional view of the stator structure after boring according to an embodiment of the present invention;

[0046] Figure 8 for Figure 3 Enlarged view of point A in the middle;

[0047] Figure 9 for Figure 7 Enlarged diagram of point B in the middle.

[0048] Explanation of reference numerals in the attached figures:

[0049] 100. Stator core; 110. Shoe part; 111. Connecting part; 112. Reserved slot;

[0050] 120. Teeth;

[0051] 130. Independent yoke; 131. Outer groove;

[0052] 140. Coil. Detailed Implementation

[0053] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without inventive effort are within the scope of protection of this invention.

[0054] It should be noted that when a component is said to be "fixed to" another component, it can be directly attached to the other component or there may be an intervening component. When a component is said to be "connected to" another component, it can be directly connected to the other component or there may be an intervening component. The terms "vertical," "horizontal," "left," "right," and similar expressions used in this document are for illustrative purposes only.

[0055] Please see Figures 1 to 9 This illustration shows an embodiment of the present invention providing a frameless torque motor stator, including an annular stator core 100. The stator core 100 is composed of multiple identical stator units evenly arranged along the circumferential direction, and each stator unit is formed by stacking stator laminations axially. The stator laminations are made of silicon steel sheets with a thickness of 0.2mm to 0.5mm, and are formed in one stamping process using a stamping die.

[0056] like Figure 1 and Figure 8 As shown, a single stator unit includes a shoe portion 110, a connecting portion 111, a tooth portion 120, and an independent yoke portion 130. The shoe portion 110 is located radially inside the stator core 100, and the shoe portions 110 of adjacent stator units are connected by the connecting portion 111, with each shoe portion 110 forming an annular pole shoe.

[0057] The connecting portion 111 is integrally formed between the circumferential ends of two adjacent shoe portions 110. It is the only structure connecting adjacent shoe portions 110 during the lamination stage, ensuring that the inner side of the stator core 100 is initially a fully closed groove with no inward opening. A reserved groove 112 is formed on the wall surface of the connecting portion 111 facing the tooth groove. The reserved groove 112 extends through the axial direction of the stator core 100, and the width of the reserved groove 112 is equal to the groove width of the semi-closed groove required for the finished stator, thus reserving a precise groove boundary for subsequent boring. The side wall of the connecting portion 111 and the circumferential side walls of the two adjacent pole shoe portions constitute the reserved groove 112. The radial thickness of the connecting portion 111 ranges from 0.5 to 2 mm to ensure the overall rigidity of the stator core 100.

[0058] The tooth 120 is located on the radially outer side of the boot 110 and extends radially outward, and the coil 140 is wound around the outer peripheral surface of the tooth 120.

[0059] Independent yokes 130 are located at the radial outer end of the toothed portion 120. The independent yokes 130 of each stator unit are circumferentially separated from each other. An outer slot 131, radially extending to the toothed portion 120, is formed between two adjacent independent yokes 130. The opening of the outer slot 131 faces the radially outer side of the stator core 100. The width and radial height of the outer slot 131 are adapted to the movement trajectory of the wire nozzle of the automatic external winding machine. The width of the outer slot 131 can be set to 1.2 to 3 times the width of the wire nozzle to avoid interference with the wire nozzle movement and to achieve high-speed continuous winding. The outer contour of the independent yoke 130 is an arc surface. After splicing the arc outer circumferences of each independent yoke 130, a complete cylindrical assembly surface is formed. After splicing multiple arc yokes, the roundness of the outer circle is ≤0.03mm. The stator core 100 as a whole is embedded into the machine base by this outer circle, ensuring assembly coaxiality.

[0060] like Figure 2 and Figure 3 As shown, coil 140 is wound around the outer circumferential surface of tooth 120. Since the outer slot 131 extends radially into tooth 120, the wire nozzle of the automatic winding machine can pass through the outer slot 131 from the outside of the stator and extend into the winding area outside tooth 120, continuously completing the multi-layer coil arrangement. Furthermore, after winding is completed, a temperature sensor can be installed inside the tooth slot, and the temperature sensor is fixed with glue.

[0061] like Figure 4 and Figure 5 As shown, after potting and curing, the potting compound fills the gaps and tooth gaps of the coil 140, the outer slot 131, the reserved slot 112, so that the coil 140, the temperature sensor and the stator core 100 are bonded into an inseparable rigid whole.

[0062] like Figure 6 , Figure 7 and Figure 9 As shown, after boring, the connecting part 111 is completely removed, the reserved groove 112 is fully exposed, the adjacent shoe parts 110 are completely isolated in the circumferential direction, and a semi-closed groove with uniform circumferential direction and uniform size is formed on the inner side of the stator.

[0063] The present invention also provides a method for manufacturing a frameless torque motor stator, comprising the following steps:

[0064] S100, laminated stator core.

[0065] An integrated stator lamination, comprising a shoe portion 110, a connecting portion 111, a toothed portion 120, and an independent yoke portion 130, is stamped in one step using a stamping die. The lamination is circumferentially connected only by the connecting portion 111 to the shoe portion 110; the independent yoke portion 130 is naturally separate, with adjacent independent yoke portions 130 directly forming the initial shape of the outer slot 131. The stator laminations are neatly stacked axially to the designed core thickness, and axial fastening is achieved through stacking, forming a rigid and complete annular core. At this point, the inner side maintains a fully closed slot structure thanks to the connecting portion 111, preventing overall deformation and avoiding misalignment of the toothed portion 120 and the shoe portion 110 during winding.

[0066] S200, automatic external winding machine for external winding forming and coil shaping.

[0067] The stacked stator core 100 is coaxially fixed to the automatic outer winding machine fixture, so that the outer slot 131 faces the wire nozzle side of the winding machine. The wire nozzle of the winding machine passes through the outer slot 131 from the radial outside of the stator core 100 and extends into the winding area outside the tooth 120, continuously winding the coil 140 according to the preset number of turns, wire diameter and number of layers.

[0068] After winding, tooling is used to shape the coil 140 and the bridging wire on the outside of the tooth 120, ensuring that the coil 140 and the bridging wire fit tightly against the cylindrical surface of the tooth 120, reducing the volume of the winding end and the axial length of the end, while avoiding the risk of insulation damage caused by loose coils. The leads of each phase winding are neatly arranged, and the lead joints are welded by ultrasonic welding or soldering, and then protected with insulating sleeves. An NTC or PTC temperature sensor is placed between two adjacent coils 140 in the tooth groove and pre-fixed with high-temperature resistant insulating glue to prevent sensor displacement during subsequent glue filling and boring processes.

[0069] S300, potting and curing.

[0070] Preparation for potting: A high-temperature release agent is evenly sprayed onto the inner surface of the potting fixture to prevent the cured adhesive from sticking to the fixture. Sealing potting fixtures are installed at both axial ends of the stator core 100. The leads of the stator core 100 are led out from the outlet holes of the bottom potting fixture. Sealing adhesive is applied to the outlet holes, and the axial end faces of the stator core 100 are sealed by the potting fixture, leaving only the potting port and vent at the top of the fixture, forming a sealed potting cavity.

[0071] Preheating of stator core 100, potting fixture, and potting compound: If a high-viscosity potting compound is used, the stator core 100, potting fixture, and potting compound must be preheated. The assembled stator core 100 and potting fixture are then placed into a curing oven and preheated to 60°C to 80°C before potting. Preheating the potting fixture and potting compound reduces the viscosity of the potting compound during potting, preventing premature curing and reduced flowability, and improving flowability for better penetration into the tooth grooves and coil gaps.

[0072] Potting: Liquid potting compound is injected uniformly into the sealed cavity from the top potting port, slowly filling all coil gaps and tooth grooves along the stator axial and radial directions. Bisphenol A type epoxy resin or alicyclic epoxy resin can be used as the potting compound, in conjunction with a suitable curing agent.

[0073] Vacuum insulation and pressure treatment: The stator core 100 and the potting fixture after potting are placed in a vacuum insulation chamber, and the vacuum is evacuated to 0.01MPa to 0.08MPa. The sealed chamber is kept at a constant temperature of 80℃ to 120℃ for 5 to 20 minutes for initial degassing. Then, the fixture is removed, potting compound is applied, and the fixture is placed back into the vacuum insulation chamber. The vacuum is evacuated to 0.01MPa to 0.08MPa, and the sealed chamber is kept at a constant temperature of 80℃ to 120℃ for 2 to 8 hours for deep degassing and high-temperature curing, ensuring that the potting compound completely fills the voids inside the potting fixture. The potting compound is fully cross-linked and cured, and the coil 140, temperature sensor, and stator core 100 are bonded into an inseparable rigid whole. The negative pressure environment causes air bubbles in the coil gaps to quickly dissipate, preventing the coil from loosening after curing, and avoiding localized insulation weaknesses and poor thermal conductivity.

[0074] Machining: After curing and demolding, use a milling machine or grinding wheel to cut away the excess potting compound overflowing from both ends of the stator axially and the radial outer surface of the independent yoke 130, and smooth the end face.

[0075] S400, boring and shaping.

[0076] After the adhesive is cured, the inner side of the stator core 100 remains closed by the connecting part 111. All connecting parts 111 are removed by boring the inner hole to expose the reserved groove 112, forming the semi-closed groove required for the finished product.

[0077] Stator core fixing: The rough-finished stator is coaxially pressed and fixed on the CNC boring machine tooling, and the positioning is based on the arc surface of the independent yoke part 130 of the stator outer circle, ensuring that the outer circle datum is coaxial with the boring machine spindle.

[0078] Coaxiality calibration: The coaxiality of the stator inner hole and the boring machine spindle is calibrated using a dial indicator, with the coaxiality error controlled within 0.02mm to ensure uniform boring allowance for all shoe sections 110. The boring tool is made of carbide, and the spindle speed, feed rate, and other cutting parameters are set according to the axial length and inner diameter of the stator.

[0079] Rough boring: Remove the main metal of the connecting part 111, leaving a finishing allowance of 0.2mm to 0.5mm on each side, so that the adjacent shoe parts 110 are initially separated, greatly reducing the machining allowance and improving machining efficiency. Also, turn off the excess potting glue on the end face where the glue inlet of the stator core 100 is located, so that the overall axial height of the stator reaches the design size.

[0080] Precision boring: Remove all the reserved allowance in one go and precisely machine to the designed inner diameter of the stator core 100, fully exposing the axial reserved groove 112 reserved in the connecting part 111. After machining, the adjacent shoe parts 110 are isolated in the circumferential direction, and the roundness of the inner circle of multiple shoe parts 110 is ≤0.03mm. A circumferentially uniform and uniformly sized semi-closed groove is formed on the inner side of the stator core 100.

[0081] Finally, the stator core 100 is subjected to performance testing. The completed motor stator is subjected to comprehensive performance testing, including mechanical performance testing, electrical performance testing, and operation simulation testing.

[0082] This invention perfectly avoids the contradiction between "narrow slots cannot be wound" and "wide slots have high cogging torque" by first winding and fixing the winding with glue, and then boring to form a semi-closed slot. The connecting part 111 has a pre-reserved slot 112 of standard width. The boring only removes the body of the connecting part 111. The slot size is formed by stamping in one step, and is not affected by boring errors. All stator slots have extremely high consistency, and the magnetic performance of the motor has very low dispersion. At the same time, it eliminates the need for a hub PCB board, reduces manual operation, and lowers the difficulty of operation, thereby improving production efficiency and reducing material and labor costs.

[0083] The frameless torque motor stator and its manufacturing method provided by this invention can be widely used in equipment such as precision optoelectronic gimbals, medical surgical actuators, vehicle-mounted silent steering and braking actuators, high-precision testing turntables, and low-speed stable servo torque motors, and have significant industrial practical value.

[0084] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A frameless torque motor stator with external winding and double slots, comprising an annular stator core, wherein the stator core is composed of multiple identical stator units uniformly arranged along the circumferential direction, characterized in that... A single stator unit includes: The boot portion is located radially inside the stator core. The boot portions of adjacent stator units are connected by a connecting portion, and all the boot portions together form an annular pole shoe. The teeth are located on the radially outer side of the boot portion and extend radially outward; An independent yoke is provided at the radial outer end of the tooth; the independent yokes of each stator unit are separated from each other circumferentially, and an outer groove is formed between two adjacent independent yokes that extends radially into the tooth; A reserved groove is provided on the wall surface of the connecting part facing the tooth groove. The reserved groove extends through the stator core along the axial direction. The width of the reserved groove is equal to the groove width of the semi-closed groove required for the finished motor stator.

2. The frameless torque motor stator with external winding and double slots as described in claim 1, characterized in that, The outer contour of each independent yoke is an arc surface, and the arc outer circumferential surfaces of each independent yoke are spliced ​​together to form a complete cylindrical assembly surface.

3. The frameless torque motor stator with external winding and double slots as described in claim 1 or 2, characterized in that, Each of the stator units is formed by stacking stator laminations along the axial direction, and the shoe part, the connecting part, the tooth part and the independent yoke part are integrally stamped from the same stator lamination.

4. The frameless torque motor stator with external winding and double slots as described in claim 1, characterized in that, The reserved groove is exposed after the connecting part is boring away, forming the opening of the semi-closed groove.

5. A method for manufacturing an externally wound, double-slotted frameless torque motor stator, characterized in that, Includes the following steps: S100. Stator laminations are stacked and formed into an annular stator core. The stator core includes multiple identical stator units. Each stator unit has a shoe portion, a connecting portion, a tooth portion, and an independent yoke portion. The shoe portions of adjacent stator units are connected by the connecting portion, and an outer groove is formed between adjacent independent yoke portions. S200. Using an automatic external winding machine, the wire tip passes through the outer slot from the radial outside of the stator core and winds the coil on the outside of the teeth. S300. The stator core with the coil wound on it is potted and cured so that the coil and the stator core are cured into one piece; S400. The inner hole of the stator core after potting and curing is bored to remove at least a portion of the connecting part, so that a semi-closed groove is formed between adjacent shoe parts.

6. The method for manufacturing a frameless torque motor stator according to claim 5, characterized in that, In step S100, the stator lamination is formed by stamping silicon steel material in one piece, and the shoe part, the connecting part, the tooth part and the independent yoke part are formed on the same stator lamination.

7. The method for manufacturing a frameless torque motor stator according to claim 5, characterized in that, Step S200 includes: S210. The stacked stator core is coaxially fixed to the automatic external winding machine fixture, so that the outer slot faces the wire nozzle side of the winding machine. S220. The winding machine nozzle passes through the outer slot from the radial outside of the stator core and extends into the winding area outside the tooth, continuously winding the coil according to the preset number of turns and layers. S230. After winding the coils for each tooth section, shape the coils and bridge wires, and weld the leads.

8. The method for manufacturing a frameless torque motor stator according to claim 5, characterized in that, Step S300 includes: S310. Install glue-filling fixtures at both ends of the stator core along the axial direction to form a sealed glue-filling cavity; S320. Inject liquid potting compound into the sealed potting cavity to fill the gaps and tooth grooves of the coil. S330. Vacuuming and heating the sealed potting cavity to achieve initial degassing, including: first performing vacuuming and heating to achieve initial degassing, then adding glue and performing vacuuming and heating to achieve deep degassing and high-temperature curing.

9. The method for manufacturing a frameless torque motor stator according to claim 8, characterized in that, The initial degassing is performed under a vacuum of 0.01 MPa to 0.08 MPa, at a temperature of 80°C to 120°C, for a duration of 5 min to 20 min; the deep degassing and high-temperature curing are performed under a vacuum of 0.01 MPa to 0.08 MPa, at a temperature of 80°C to 120°C, for a duration of 2 h to 8 h; and before injecting the liquid potting compound, the stator core, potting compound, and potting fixture are preheated to 60°C to 80°C.

10. The method for manufacturing a frameless torque motor stator according to claim 5, characterized in that, In step S400, the boring process includes a rough boring process and a finish boring process: S410, the rough boring process removes the main metal of the connecting part, leaving a finishing allowance of 0.2mm to 0.5mm on one side; S420, The precision boring process removes all the reserved allowance, causing the adjacent boot parts to separate from each other in the circumferential direction, and the reserved groove is fully exposed to form the semi-closed groove; During boring, the coaxiality error between the outer circle of the stator core and the spindle of the boring machine is controlled within 0.02mm.

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