High-precision skewing process and equipment for skewed slot stator core

Abstract

The invention discloses a high-precision skewing process and equipment for a skewed slot stator core, and relates to the field of motor stators, and the high-precision skewing process comprises the steps: firstly obtaining the thickness and number of stator single sheets and a target skewed slot angle, and calculating a unit torsion angle; and then, by establishing a deviation analysis model of the thickness of a stator single sheet and the total length of an iron core, correcting a unit torsion angle to obtain a corrected torsion angle capable of compensating an inherent system error of step lamination, when equipment executes skew, controlling the core rod to synchronously feed and rotate according to the corrected torsion angle and the thickness of the single sheet, and withdrawing after lamination is completed, according to the technical system, precise closed-loop control over the skew angle of each punching sheet is achieved, the technical system thoroughly eliminates the angle accumulated deviation existing at the laminating end point in a traditional method, it is ensured that the actual skew angle of the final iron core is highly matched with the designed target, and therefore the extreme precision and batch production consistency of the skewed slot stator iron core are fundamentally guaranteed.

Description

Technical Field

[0001] This invention relates to the field of motor stators, specifically to a high-precision skewing process and equipment for skewed slot stator cores. Background Technology

[0002] In the field of motor manufacturing, skewed stator core technology is commonly used to reduce tooth harmonics and higher harmonics in the air gap magnetic field, thereby reducing motor torque ripple and electromagnetic noise and improving back EMF waveform. Skewed slots, that is, the slot lines of the stator core are not parallel to the motor axis, but are distributed in a spiral shape. The core of this technology is to give the core a precise and consistent total skew angle (usually one stator tooth pitch).

[0003] Currently, the main manufacturing methods for skewed stator cores include manual skewing, segmented pre-twisting with simple fixtures, and overall skewing with special equipment. Manual skewing relies heavily on the experience of operators, resulting in poor consistency, low efficiency, and difficulty in meeting the requirements of mass production. While segmented pre-twisting with simple fixtures improves efficiency to some extent, cumulative errors occur in the angle connection between segments during the stacking process, and a continuous spiral shape cannot be achieved, affecting the optimization of the skewed slot effect. Summary of the Invention

[0004] The purpose of this invention is to provide a high-precision skewing process and equipment for skewed stator cores to solve the problems mentioned in the background art.

[0005] To achieve the above objectives, the present invention provides the following technical solution: a high-precision skewing process for a skewed stator core, characterized by comprising the following steps:

[0006] Step 1: Pre-processing, the stator single piece of the stator core is placed on the straight slot mandrel, and a gap is left between the twisted mandrel and the straight slot mandrel. During the stacking process, the core is pre-clamped by the clamping fixture.

[0007] Step 2: Calculate the unit angle and obtain the specifications of the stator core, including the thickness of the stator laminations, the number of stator laminations, and the skew angle of the stator core. Based on the skew angle and the number of stator laminations, obtain the unit torsion angle for each stator lamination. Then, establish a deviation analysis by using the thickness of the stator laminations and the total length of the stator core after pre-clamping to obtain the correction coefficient. Correct the unit torsion angle and output the corrected torsion angle.

[0008] Step 3: Perform skew. To perform skew, control the straight groove mandrel and the skewed mandrel to execute a torsion strategy along their axial direction. The torsion strategy includes the following steps:

[0009] For a single stator lamination, the straight slot mandrel retraction distance n, the tortuous mandrel feed distance m, and the thickness of the single stator lamination set as d, then 1.5d > n > d, d > m > 0.5d, and the straight slot mandrel drives the remaining stator laminations to rotate by the corrected torsion angle.

[0010] Repeat the operation until the preset number of laminations are completed to form a skewed iron core with a total skew angle of the target angle.

[0011] Step 4: Core fixing. After the straight slot mandrel is removed, the inclined slot mandrel is fixed by applying a preload force based on the stacking coefficient.

[0012] Preferably, the clamping fixture uses multiple pressure heads distributed along the axial direction of the stator core to uniformly clamp the outermost circular surface of the core.

[0013] Preferably, the deviation analysis method includes establishing a geometric relationship model between the ideal spiral groove shape and the actual stepped groove shape, and calculating a correction coefficient through the model to compensate for the cumulative angular error caused by the stepped approximation of the ideal spiral.

[0014] Preferably, the geometric relationship model unfolds the ideal spiral groove into a straight line and the actual stepped groove into a stepped broken line by using the radius and total height of the iron core. The correction coefficient is obtained by calculating the ratio of the total arc length of the straight line to the total projected arc length of the stepped broken line.

[0015] Preferably, the method for fixing the iron core in step four includes welding, and the welding process is carried out in a segmented, symmetrical, and spaced welding sequence.

[0016] Preferably, the method for removing the mandrel in step four includes, after completing the twisting of the last lamination, the drive system stops rotating the mandrel, controls the straight-groove mandrel to move out in a straight line, and the twisted mandrel rotates out until it is completely detached from the core.

[0017] Furthermore, this invention also provides a high-precision skewing device for a skewed stator core, comprising a partition plate, a torsion mandrel, and a straight slot mandrel. The partition plate has drive mechanisms on both sides for linear feeding and rotational movement of the mandrel. The straight slot mandrel passes through the stator core in the through hole of the partition plate and is pre-clamped by a clamping fixture. The torsion mandrel is inserted from the other end of the stator core and abuts against the straight slot mandrel. During skewing, the drive mechanism controls the straight slot mandrel to retract according to the distance of each stator lamination while simultaneously rotating to correct the torsion angle. It also controls the torsion mandrel to feed according to the distance of each stator lamination, forming individual skews on the stator laminations until a preset number of laminations are completed, forming a skewed core with a total skew angle equal to the target angle.

[0018] Preferably, the drive mechanism includes a first servo motor, the horizontal moving end of the first servo motor is fixedly connected to a fixed base, and a second servo motor is fixedly mounted on the fixed base.

[0019] Preferably, an L-shaped plate is fixedly installed on the mounting base, and the output shaft of the second servo motor passes through the L-shaped plate and is fixedly connected to the corresponding mandrel.

[0020] Preferably, a base is fixedly mounted on the bottom of the first servo motor.

[0021] In summary, the beneficial effects of this invention are:

[0022] This invention establishes a deviation analysis model based on the total height of the core and the thickness of a single lamination, calculates the precise corrected torsion angle, and compensates for the inherent systematic error of the stepped stacking method relative to the ideal spiral from the algorithm source. Combined with a clamping fixture with an arc-shaped clamping surface and a multi-point clamping head, as well as a high-precision skewing device driven by dual servo motors, it achieves precise closed-loop control of the skew angle of each lamination. This technology system completely eliminates the angle accumulation deviation at the end of the stacking process that exists in traditional methods, ensuring that the actual skew angle of the final core is highly consistent with the design target, thereby fundamentally guaranteeing the ultimate precision and batch production consistency of the skewed stator core. Attached Figure Description

[0023] To more clearly illustrate the technical solutions in the embodiments of the invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0024] Figure 1 This is a schematic diagram of the overall process framework of a high-precision torsion process for a skewed stator core according to the present invention.

[0025] Figure 2 This is a schematic diagram of the overall structure of a high-precision skew-slot stator core twisting device according to the present invention;

[0026] Figure 3 This is a schematic diagram of the main structure of a high-precision skewing device for a skewed stator core according to the present invention;

[0027] Figure 4 This is a schematic diagram of the structure from the bottom view in a high-precision skewing device for a skewed stator core according to the present invention;

[0028] Figure 5 This is an initial schematic diagram of the high-precision twisting process for a skewed stator core according to the present invention.

[0029] Figure 6 This is a schematic diagram of the high-precision twisting process of a skewed stator core according to the present invention after twisting.

[0030] The markings in the attached diagram are described as follows: base 10; first servo motor 11; fixed seat 12; L-shaped plate 13; second servo motor 14; partition 15; torsion mandrel 16; straight groove mandrel 17. Detailed Implementation

[0031] The present invention will now be described in further detail with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention. These drawings are simplified schematic diagrams, which are only used to illustrate the basic structure of the present invention in a schematic manner, and therefore only show the components related to the present invention.

[0032] To facilitate understanding of the present invention, a more complete description of the invention will be given below with reference to the accompanying drawings, which illustrate several embodiments of the invention. However, the invention can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided so that the disclosure of the invention will be more thorough and complete.

[0033] All features disclosed in this specification, or all steps in all disclosed methods or processes, may be combined in any way, except for mutually exclusive features and / or steps.

[0034] Any feature disclosed in this specification (including any appended claims, abstract, and drawings) may be replaced by other equivalent or similar features for a similar purpose, unless specifically stated otherwise. That is, unless specifically stated otherwise, each feature is merely one example of a series of equivalent or similar features.

[0035] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection, a direct connection, or an indirect connection through an intermediate medium; they can refer to the internal communication of at least two elements or the interaction relationship of at least two elements, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0036] Please see Figures 1-6This invention provides an embodiment of a high-precision tilting device for a skewed stator core, comprising two bases 10, each base 10 having a drive mechanism for linear feeding and rotational movement of the mandrel, separated by a partition 15. The clamping fixture uses multi-point pressure heads distributed along the axial direction of the stator core to uniformly clamp the outermost circular surface of the core. The drive mechanism includes a first servo motor 11, the horizontal moving end of which is fixedly connected to a fixed base 12. An L-shaped plate 13 is fixedly mounted on the fixed base 12, and a second servo motor 14 is fixedly mounted on the L-shaped plate 13. The output shaft passes through the L-shaped plate 13 and is fixedly connected to the corresponding mandrel. The mandrel includes a torsion mandrel 16 and a straight slot mandrel 17. The straight slot mandrel 17 passes through the stator core and is pre-clamped by a clamping fixture. The torsion mandrel 16 is inserted from the other end of the stator core and abuts against the straight slot mandrel 17. When the drive mechanism is skewed, it controls the straight slot mandrel 17 to move back according to the distance of each stator lamination and rotates to correct the torsion angle. It controls the torsion mandrel 16 to feed according to the distance of each stator lamination, forming a skewed core with a total skew angle of the target angle after completing the skewed core of the preset number of laminations.

[0037] A skewed slot refers to a slot in the stator core that is not parallel to the motor axis but is twisted at an angle in a spiral shape. This is in contrast to a straight slot. The core purpose of a skewed slot is to reduce a series of adverse effects caused by the non-sinusoidal distribution of the air gap magnetic field, thereby improving the performance and operating quality of the motor. The skew angle is a key design parameter that directly affects the effect of harmonic suppression.

[0038] Therefore, when twisting each skewed stator core, it is necessary to calculate the unit angle to control the drive mechanism to execute the unit angle of twist.

[0039] It should be noted that, in this embodiment, the calculation of the unit angle includes the following steps:

[0040] Step 1: Obtain the specifications of the stator core, including the thickness of the stator laminations, the number of stator laminations, and the skew angle of the stator core. Based on the skew angle and the number of stator laminations, obtain the unit torsion angle for each stator lamination.

[0041] For example, taking an 18-slot stator core with one slot skewed as an example, the calculated skew angle is: 360 / 18 = 20°.

[0042] The thickness of each stator lamination is 0.35mm, and there are a total of 77 laminations. The total core height is calculated to be 27mm.

[0043] The angle difference between each stacked piece is 20 / 77 = 0.2597°, which is taken as the unit torsion angle.

[0044] Specifically, a perfect skewed core has a slot shape that is a continuous, uniform spiral. Since the laminations are stacked one by one, each lamination is an independent straight slot. What we actually manufacture is a stepped, zigzag line to approximate the ideal spiral. This approximation method leads to a slight path deviation between the actual slot shape and the ideal spiral. Although the deviation of a single lamination is extremely small, it accumulates over the entire length of the core and may cause a non-negligible deviation between the effective skew angle and the design target angle. Therefore, the second step below eliminates this accumulated deviation.

[0045] Step 2: By establishing a deviation analysis based on the thickness of the stator single piece and the total length of the stator core, the correction coefficient is obtained, and the unit torsion angle is corrected to output the corrected torsion angle;

[0046] It should be noted that the deviation analysis method includes establishing a geometric relationship model between the ideal spiral groove and the actual stepped groove. The model is used to calculate correction coefficients to compensate for the cumulative angular error caused by the stepped approximation of the ideal spiral. The geometric relationship model unfolds the ideal spiral groove into a straight line and the actual stepped groove into a stepped broken line using the radius and total height of the iron core. The correction coefficient is obtained by calculating the ratio of the total arc length of the straight line to the total projected arc length of the stepped broken line.

[0047] We need to analyze the geometric relationship between the broken line formed by "rotating by one unit torsion angle α and advancing by one thickness t" and the ideal spiral formed by "total height H and total angle θ":

[0048] Unfold the outer (or inner) circle of the iron core into a rectangle. The ideal helix is ​​a diagonal line within this rectangle.

[0049] The height of the rectangle = the total height of the iron core H = N × t (where t is the thickness of a single piece);

[0050] The width of the rectangle equals the perimeter of the stator core (at that radius), C = 2πR;

[0051] The total lift angle of the ideal spiral is the target skew angle θ;

[0052] The axial movement distance of each step is t, and the circumferential movement distance of each step is △L=R*α*π / 180.

[0053] In an ideal spiral, the ideal circumferential rotation angle corresponding to each advance of a single sheet thickness t is not a constant. However, for a uniform spiral, its average value can serve as a more precise target. A more direct method is to ensure that the end position of the last sheet coincides with the end position of the ideal spiral. Through geometric analysis, the correction coefficient k can be approximately calculated using the following formula:

[0054] K=θ / [arctan(H*tanθ / Nt)*N];

[0055] The corrected torsion angle is obtained as K*α.

[0056] During the skewing process, for a single stator lamination, the straight slot mandrel retraction distance n, the skew mandrel feed distance m, and the thickness of the single stator lamination is set to d, then 1.5d > n > d, d > m > 0.5d. The straight slot mandrel drives the remaining stator laminations to rotate at the corrected torsion angle, and the operation is repeated until a preset number of laminations are formed to create a skewed core with a total skew angle equal to the target angle.

[0057] First, the first servo motor 11 is driven to retract the straight slot mandrel 17 by 1.2 times the thickness of the stator lamination, while the torsion mandrel 16 is fed forward by 0.8 times the thickness of the stator lamination. Then, the second servo motor 14 is controlled to rotate the remaining stator laminations by the corrected torsion angle until a preset number of laminations are formed to create a skewed core with a total torsion angle equal to the target angle.

[0058] Execute the torsion strategy by controlling the straight groove mandrel and the torsion mandrel to perform a torsion strategy along their axial direction, the torsion strategy including the following steps:

[0059] After the last lamination is twisted, the drive system stops rotating the mandrel and controls the straight slot mandrel to move out in a straight line. The twisted mandrel rotates out until it is completely detached from the core. Finally, the core is fixed, either by welding, using a segmented, symmetrical, and spaced welding sequence with 4 or 6 welds to fix the outer circle of the lamination, or by glue fixation, fixing each stator lamination individually with glue.

[0060] During actual runtime:

[0061] Set the target total skew angle to 20° (18 slots skewed by one slot);

[0062] Stator single-piece thickness: 0.35mm;

[0063] Stator unit quantity: 77 pieces;

[0064] Theoretical total height of the iron core: 27mm;

[0065] The angle difference between each stacked piece is 20 / 77 = 0.2597°, which is taken as the unit torsion angle.

[0066] Establish a geometric relationship model and unfold the ideal spiral into a slanted straight line: the total height of the ideal spiral is H = 27mm, the actual total height of the stacking is H_actual = 77 × 0.35 = 26.95mm, the target skew angle is θ = 20°, then the correction coefficient k≈ 1.001855, and the corrected torsion angle≈ 0.2602°.

[0067] Twisting operation execution process:

[0068] Initial positioning:

[0069] The straight slotted mandrel 17 is fully inserted from left to right, and the torsion mandrel 16 is inserted from right to left, abutting against the straight slotted mandrel 17. The first stator lamination is placed in, ensuring complete alignment with the straight slotted mandrel 17. The first servo motor 11 drives the straight slotted mandrel 17 to retract 0.35mm. The first servo motor 11 simultaneously drives the torsion mandrel 16 to advance 0.35mm. The second servo motor 14 drives the two mandrels to rotate synchronously to an absolute angle of n × 0.2602°. The (n+1)th lamination is placed in, naturally positioned in the skewed position. After the 77th lamination is stacked, the total skew angle reaches approximately 20.037°. All rotational movements are stopped, and only the first servo motor 11 is activated. The straight slotted mandrel 17 and the torsion mandrel 16 maintain their final angle and synchronously exit the core in a straight line.

[0070] Maintain the compressed state and fix it with 4 welds. The welding sequence is: 0°→180°→90°→270° segmented symmetrical welding to ensure minimal welding thermal deformation.

[0071] The actual tilt angle at a theoretical height of 27mm using traditional methods is approximately 20.130° (error +0.130°).

[0072] The actual skew angle of this high-precision method at a theoretical height of 27mm is approximately 20.000° (with an error close to 0°).

[0073] In summary, this invention establishes a deviation analysis model based on the total core height and single-piece thickness to calculate a precise corrected torsion angle. This algorithm compensates for the inherent systematic error of the stepped stacking method relative to the ideal spiral from the algorithmic source. Combined with a clamping fixture featuring an arc-shaped clamping surface and multi-point pressure heads, and a high-precision skewing device driven by dual servo motors, it achieves precise closed-loop control of the skew angle of each lamination. This technical system completely eliminates the cumulative angle deviation at the stacking endpoint present in traditional methods, ensuring that the actual skew angle of the final core closely matches the design target, thereby fundamentally guaranteeing the ultimate precision and batch production consistency of the skewed stator core.

[0074] The above description is merely a specific embodiment of the invention, but the scope of protection of the invention is not limited thereto. Any changes or substitutions conceived without inventive effort should be included within the scope of protection of the invention. Therefore, the scope of protection of the invention should be determined by the scope defined in the claims.

Claims

1. A high-precision skewing process for skewing stator cores, characterized in that: Includes the following steps: Step 1: Pre-processing, the stator single piece of the stator core is placed on the straight slot mandrel, and a gap is left between the twisted mandrel and the straight slot mandrel. During the stacking process, the core is pre-clamped by the clamping fixture. Step 2: Calculate the unit angle and obtain the specifications of the stator core, including the thickness of the stator laminations, the number of stator laminations, and the skew angle of the stator core. Based on the skew angle and the number of stator laminations, obtain the unit torsion angle for each stator lamination. Then, establish a deviation analysis by using the thickness of the stator laminations and the total length of the stator core after pre-clamping to obtain the correction coefficient. Correct the unit torsion angle and output the corrected torsion angle. Step 3: Perform skewing, controlling the straight groove mandrel and the skewed mandrel to perform a torsion strategy along their axial direction. The torsion strategy includes the following steps: For a single stator lamination, the straight slot mandrel retraction distance n, the tortuous mandrel feed distance m, and the thickness of the single stator lamination set as d, then d < n < 1.5d, 0.5d < m < d, and the straight slot mandrel drives the remaining stator laminations to rotate by the corrected torsion angle. Repeat the operation until the preset number of laminations are completed to form a skewed iron core with a total skew angle of the target angle. Step 4: Core fixing. After the straight slot mandrel is removed, the inclined slot mandrel is fixed by applying a preload force based on the stacking coefficient.

2. The high-precision skewing process for a skewed stator core according to claim 1, characterized in that: The clamping fixture uses multiple pressure heads distributed along the axial direction of the stator core to uniformly clamp the outermost circular surface of the core.

3. The high-precision skewing process for a skewed stator core according to claim 1, characterized in that: The deviation analysis method includes establishing a geometric relationship model between the ideal spiral groove shape and the actual stepped groove shape, and calculating correction coefficients through this model to compensate for the cumulative angular error caused by the stepped approximation of the ideal spiral.

4. The high-precision skewing process for a skewed stator core according to claim 3, characterized in that: The geometric relationship model unfolds the ideal spiral groove into a straight line and the actual stepped groove into a stepped broken line by using the radius and total height of the iron core. The correction coefficient is obtained by calculating the ratio of the total arc length of the straight line to the total projected arc length of the stepped broken line.

5. The high-precision skewing process for a skewed stator core according to claim 1, characterized in that: The method for fixing the iron core in step four includes welding, which is carried out in a segmented, symmetrical, and spaced welding sequence, and also includes glue fixing, fixing each stator piece individually with glue.

6. The high-precision skewing process for a skewed stator core according to claim 5, characterized in that: The method for removing the mandrel in step four includes, after completing the twisting of the last lamination, the drive system stops rotating the mandrel, controls the straight-groove mandrel to move out in a straight line, and the twisted mandrel to rotate out until it is completely detached from the core.

7. A high-precision skew-twisting device for a skewed stator core, characterized in that: The system includes a partition (15), a torsion mandrel (16), and a straight slot mandrel (17). The partition (15) has a drive mechanism on each side for linear feeding and rotational movement of the mandrel. The straight slot mandrel (17) passes through the stator core in the through hole of the partition (15) and is pre-clamped by a clamping fixture. The torsion mandrel (16) is inserted from the other end of the stator core and abuts against the straight slot mandrel (17). When the drive mechanism is torturing, it controls the straight slot mandrel (17) to move back according to the distance of each stator lamination and rotates to correct the torsion angle. It controls the torsion mandrel (16) to feed according to the distance of each stator lamination, forming a torsion of each stator lamination until a preset number of laminations are formed to form a skewed core with a total torsion angle of the target angle.

8. A high-precision skew-twisting device for a skewed stator core according to claim 7, characterized in that: The driving mechanism includes a first servo motor (11) for driving linear motion, and a fixed base (12) is fixedly connected to the horizontal moving end of the first servo motor (11). A second servo motor (14) for driving rotation is fixedly installed on the fixed base (12).

9. A high-precision skew-twisting device for a skewed stator core according to claim 8, characterized in that: An L-shaped plate (13) is fixedly installed on the fixed base (12), and the output shaft of the second servo motor (14) passes through the L-shaped plate (13) and is fixedly connected to the corresponding mandrel.

10. A high-precision skew-twisting device for a skewed stator core according to claim 9, characterized in that: The bottom of the first servo motor (11) is fixedly mounted with a base (10).

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