A laser cutting method for a conductor of a disc type stator winding

Abstract

This invention provides a laser cutting method for conductors used in disc stator windings, comprising: S1, obtaining an ideal cutting path file; S2, dividing the ideal cutting path of the conductor into external ideal sub-paths and internal ideal sub-paths; S3, performing an initial cut on a metal slab based on each external ideal sub-path to obtain a first image; S4, processing the first image to obtain an initial cutting path file; S5, performing coordinate matching between the initial cutting path file and the ideal cutting path file to obtain the spatial deviation between the inner endpoint of each external actual sub-path and the outer endpoint of the corresponding internal ideal sub-path; S6, determining the optimal internal path based on the spatial deviation between the inner endpoint of each external actual sub-path and the outer endpoint of the corresponding internal ideal sub-path; S7, performing a secondary cut on the metal slab based on each optimal internal path. This invention optimizes subsequent cutting paths based on the initial cutting results to avoid the influence of heat accumulation and stress on subsequent cutting, ensuring the cutting quality of the inner solder pad segment.

Description

Technical Field

[0001] This invention belongs to the field of conductor processing technology for windings, and specifically relates to a laser cutting method for conductors used in disc stator windings. Background Technology

[0002] In the field of electric motors, disc stator windings are mainly manufactured using two mainstream methods: one is to wind enameled wire onto an insulating frame to form an enameled wire winding; the other is to etch planar copper foil lines onto a PCB substrate to form a PCB printed winding. However, enameled wire windings suffer from low space utilization, making it difficult to increase the power density of the motor; while PCB printed windings have higher space utilization, the copper foil thickness is limited by the PCB manufacturing process, which restricts current carrying capacity and heat dissipation performance.

[0003] To overcome the above-mentioned defects, the invention patent with application number 2023105569836 provides a disc-type stator winding. The disc-type stator winding includes a first layer of copper plate and a second layer of copper plate. Both the first layer of copper plate and the second layer of copper plate are formed by laser cutting pure copper plates to form multiple strip conductors and then splicing them together. In addition, the winding conductors correspondingly arranged on the first layer of copper plate and the second layer of copper plate need to be stacked vertically and horizontally, and the outer connection ends (i.e., outer solder pads) and inner connection ends (i.e., inner solder pads) of the two are electrically connected to form the phase windings of the disc-type stator winding.

[0004] Currently, the traditional method for cutting and manufacturing copper plates of various layers is to sequentially cut each path on a pure copper plate in one go, according to the ideal cutting path of each conductor in the ideal cutting path file. However, during the one-time cutting process, as the cutting path extends, heat accumulates continuously, causing local thermal expansion and contraction of the material. This results in a deviation between the actual cutting path and the ideal cutting path. At the same time, residual stress inside the material during continuous cutting also changes the cutting path. This change in the cutting path causes the actual position of the inner connection end to deviate from the ideal position of the inner connection end. Thus, when the winding conductors of the first and second copper plates are stacked crosswise to ensure precise alignment of their outer connection ends, their inner connection ends cannot be properly aligned (i.e., the alignment accuracy of their inner connection ends is poor), affecting the welding quality and consequently the reliability of the winding resistance. Summary of the Invention

[0005] In view of the shortcomings of the prior art, the purpose of this invention is to provide a laser cutting method for conductors of disc stator windings. The method first performs an initial cut on the metal blank according to the ideal external cutting path of each conductor, and then optimizes the subsequent cutting path based on the initial cutting situation to reduce or avoid the influence of heat accumulation and residual stress on the inner solder pad section path, so as to ensure the cutting quality of the inner solder pad section and thus ensure the reliability of the winding resistance.

[0006] To achieve the above and other related objectives, the present invention provides a laser cutting method for conductors used in disc stator windings, the cutting method comprising:

[0007] S1. Obtain the ideal cutting path file for the metal slab; the ideal cutting path file for the metal slab includes the ideal cutting paths for each conductor.

[0008] S2. Divide the ideal cutting path of each conductor into an external ideal sub-path and an internal ideal sub-path; wherein, the external ideal sub-path includes the ideal path of the outer pad segment, the ideal path of the outer bridging segment, the ideal path of the working segment, and the ideal path of the inner bridging segment connected in sequence; the internal ideal sub-path includes the ideal path of the inner pad segment.

[0009] S3. Perform initial cutting of the metal slab based on the ideal external paths of each conductor, and obtain the first image of the metal slab after initial cutting.

[0010] S4. Process the first image to extract the actual external sub-paths of each conductor on the metal slab, and then obtain the initial cutting path file of the metal slab.

[0011] S5. Perform coordinate matching between the initial cutting path file and the ideal cutting path file of the metal slab to obtain the spatial deviation between the inner endpoints of each external actual sub-path and the corresponding outer endpoints of the internal ideal sub-path.

[0012] S6. If there is no spatial deviation between the inner endpoint of the actual external sub-path and the outer endpoint of the corresponding ideal internal sub-path, then the corresponding ideal internal sub-path is the optimal internal path; if there is a spatial deviation between the inner endpoint of the actual external sub-path and the outer endpoint of the corresponding ideal internal sub-path, then based on the coordinates of the inner endpoint of the actual external sub-path and the coordinates of the outer endpoint of the ideal internal pad segment, the transition path with the highest matching degree is automatically found in the preset transition path template library, and the optimal internal path is generated based on the transition path with the highest matching degree and the ideal internal pad segment.

[0013] S7. Perform secondary cutting on the metal blank after the initial cutting according to each optimal internal path to obtain each conductor.

[0014] This invention optimizes the one-time cutting scheme for each conductor path into a two-step cutting scheme. The core of this two-step cutting scheme is to first cut the metal blank according to the ideal external path of each conductor, and then intelligently match the transition path according to the actual cutting situation of the external path and the processing requirements of the ideal path of the inner pad segment to compensate for and eliminate the positional deviation caused by the actual cutting of the external path. Finally, the subsequent cutting is carried out according to the matched transition path and the original ideal path of the inner pad segment to ensure the processing quality of the inner pad segment, thereby improving the accuracy of the relative position between the inner and outer pad segments and improving the reliability of the subsequent stator winding.

[0015] Preferably, the method for automatically finding the transition path with the highest matching degree is as follows: deviate from all transition paths in the transition path template library; use the Euclidean distance algorithm to calculate the first Euclidean distance between the outer endpoint of each transition path and the inner endpoint of the actual external sub-path, and the second Euclidean distance between the outer endpoint of each transition path and the outer endpoint of the corresponding inner pad segment ideal path, to obtain the sum of the Euclidean distances of each transition path; select the transition path with the smallest sum of Euclidean distances as the transition path with the highest matching degree; the transition path matching based on the Euclidean distance algorithm has the advantages of simple calculation and easy implementation.

[0016] Preferably, the processing of the first image is performed in the OpenCV tool; since the OpenCV tool provides an extremely rich set of image processing functions and can be installed free of charge on a computer (such as a PC), the development cost of visual recognition is greatly reduced.

[0017] Preferably, the processing of the first image includes image preprocessing and contour extraction; the image preprocessing includes grayscale processing, noise reduction processing, and binarization processing; the contour extraction includes edge detection.

[0018] Preferably, the noise reduction process employs Gaussian filtering or bilateral filtering.

[0019] Preferably, the binarization process employs the Otsu adaptive thresholding method, the fixed thresholding method, or the adaptive local thresholding method.

[0020] Preferably, edge detection employs the Canny edge detection algorithm, the Sobel algorithm, or the Laplacian algorithm.

[0021] Preferably, step S4 further includes saving and outputting the initial cutting path file, wherein the initial cutting path file is saved in DXF, SVG, or YC format to facilitate verification of the image processing results.

[0022] As described above, the laser cutting method for conductors used in disc stator windings of the present invention has the following beneficial effects:

[0023] This invention first performs an initial cut on the metal slab based on the ideal external paths of each conductor. Then, based on the initial cutting of the external paths and the processing requirements of the corresponding ideal paths of the inner pad segments, it intelligently matches a transition path to compensate for and eliminate positional deviations caused by the actual cutting of the external paths. Finally, it performs subsequent cutting based on the matched transition path and the original ideal paths of the inner pad segments. Because this invention first cuts the external paths of the conductors, the slab has sufficient time to release heat and stress before the inner paths are cut, effectively avoiding the impact of heat accumulation and residual stress generated by the cutting of the external paths on the cutting quality of the subsequent optimal inner paths. The transition path in the optimal inner paths is obtained by matching the actual external paths of the conductors with the ideal paths of the corresponding inner pad segments. This transition path can effectively compensate for and eliminate positional deviations caused by the actual external paths, thereby ensuring the cutting quality of the inner pad path segments, reducing or avoiding shape and positional deviations of the inner pad segments, and thus improving the accuracy of the relative position between the inner and outer pad segments, and improving the reliability of the subsequent stator windings. Attached Figure Description

[0024] Figure 1 This is a flowchart of the laser cutting method for conductors used in disc stator windings, which is involved in this invention.

[0025] Figure 2 This is a schematic diagram illustrating the process of cutting and separating a metal slab into multiple circumferentially distributed conductors.

[0026] Figure 3 This is a schematic diagram of a conductor.

[0027] Figure 4 for Figure 3 A magnified view of a portion at point A.

[0028] Metal slab 1, conductor 2, outer region 2a, inner region 2b, outer pad section 21, outer bridging section 22, working section 23, inner bridging section 24, inner pad section 25, transition section 26. Detailed Implementation

[0029] The following specific embodiments illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification.

[0030] Please see Figures 1 to 4It should be understood that the structures, proportions, sizes, etc., illustrated in the accompanying drawings are merely for illustrative purposes to aid those skilled in the art and to facilitate understanding and reading. They are not intended to limit the scope of the invention and therefore have no substantial technical significance. Any modifications to the structure, changes in proportions, or adjustments to size, without affecting the effectiveness and purpose of the invention, should still fall within the scope of the technical content disclosed in this invention. Furthermore, the terms such as "upper," "lower," "left," "right," "middle," and "one" used in this specification are merely for clarity and not intended to limit the scope of the invention. Changes or adjustments to their relative relationships, without substantially altering the technical content, should also be considered within the scope of the invention's implementation.

[0031] The core of this invention is to provide a laser cutting method for conductors used in disc stator windings. This method addresses the problem in the prior art where, during a single conductor cutting process, heat accumulation and stress concentration cause the actual cutting path to deviate from the ideal cutting path, leading to changes in the shape and position of the inner solder pads within the conductor. This method ensures the connection accuracy of the upper and lower inner solder pads in the stator winding and improves the reliability of the stator winding.

[0032] Figure 1 A flowchart illustrating a laser cutting method for a conductor used in a disc stator winding, as provided in an embodiment of the present invention, is shown below. Figure 1 As shown, the cutting method includes:

[0033] S1. Obtain the ideal cutting path file for the metal slab 1; the ideal cutting path file for the metal slab 1 includes the ideal cutting paths for each conductor 2.

[0034] like Figure 2 As shown, the conductors 2 in the same layer of the disc stator winding are evenly distributed in the circumferential direction and are cut from the same metal blank 1; the metal blank 1 is made of various existing conductive materials such as copper, aluminum or silver, and there is no limitation on this. In this embodiment, the metal blank 1 is made of copper.

[0035] In this embodiment, as Figure 2 and Figure 3 As shown, conductor 2 is generally meandering, and includes an outer pad segment 21, an outer bridging segment 22, a working segment 23, an inner bridging segment 24 and an inner pad segment 25 connected sequentially from the outside to the inside, with smooth transitions between each segment to reduce stress concentration during cutting.

[0036] like Figure 2 As shown, in order to save materials, the metal slab 1 is preferably made of annular plate.

[0037] It should be noted that the ideal cutting path file for the metal slab 1 is a CAD drawing pre-laid in CAD software based on the required number and ideal shape of the conductors 2. Since each conductor 2 has two radial boundary lines extending in the radial direction, the ideal radial boundary lines of each conductor 2 are taken as the ideal cutting path in the ideal cutting path file for the metal slab 1.

[0038] S2. Divide the ideal cutting path of each conductor 2 into an external ideal sub-path and an internal ideal sub-path; wherein, the external ideal sub-path includes the ideal path of the outer pad segment, the ideal path of the outer bridging segment, the ideal path of the working segment, and the ideal path of the inner bridging segment connected in sequence; the internal ideal sub-path includes the ideal path of the inner pad segment.

[0039] like Figure 2 and Figure 3 As shown, since the inner pad segments 25 of each conductor 2 on the metal slab 1 are arranged relatively closely, when the ideal cutting paths of each conductor 2 in the ideal cutting path file are directly followed to complete the one-time cutting of each path on the metal slab 1, the path deviation is easily caused by heat accumulation and stress release, making it difficult to guarantee the processing quality of the inner pad segments 25.

[0040] To improve the machining quality of the inner solder pad segment 25, such as Figure 3 As shown, the present invention divides the conductor 2 into an external region 2a and an internal region 2b with the inner end of the inner bridging segment 24 as the boundary. The external region 2a is cut first, while the internal region 2b is cut first. At this time, the ideal cutting path of each conductor 2 is also divided into an external ideal sub-path and an internal ideal sub-path.

[0041] Specifically, such as Figure 3 and Figure 4 As shown, the outer region 2a includes an outer pad segment 21, an outer bridging segment 22, a working segment 23, and an inner bridging segment 24 connected in sequence, and the inner region 2b includes an inner pad segment 25 and a transition segment 26 between the inner pad segment 25 and the inner bridging segment 24 (i.e., Figure 4 The area between the two dashed lines); at this time, the external ideal sub-path includes the ideal path of the outer pad segment, the ideal path of the outer bridging segment, the ideal path of the working segment, and the ideal path of the inner bridging segment connected in sequence; the internal ideal sub-path includes the ideal path of the transition segment and the ideal path of the inner pad segment connected in sequence.

[0042] S3. The metal blank 1 is initially cut according to the ideal external paths of each conductor 2, and the first image of the metal blank 1 after the initial cut is obtained.

[0043] Since the outer region 2a of conductor 2 is cut before the inner region 2b, it is only necessary to import the ideal cutting path file into the control system of the cutting machine and cut the outer region 2a of each conductor 2 on the metal blank 1 according to each external ideal sub-path in the ideal cutting path file to complete the initial cutting of the metal blank 1.

[0044] After the initial cutting of the metal slab 1, there is sufficient time for the heat and stress to be released, allowing the metal slab 1 to reach a stable state. This avoids the heat accumulation and residual stress generated by the cutting of the outer path from affecting the cutting quality of the subsequent inner path.

[0045] After all the outer regions 2a of conductors 2 are cut, a conductor slit will be formed between the outer regions 2a and the metal blank 1. In order to fix the position of the outer regions 2a and the metal blank 1 after cutting and to achieve insulation isolation, insulating glue needs to be filled into the conductor slit. The insulating glue can be any existing electrical isolation material such as epoxy resin or polyurethane, and there is no limitation on it.

[0046] Understandably, the first image was obtained by capturing images using an industrial camera or other imaging device.

[0047] S4. Process the first image to extract the actual external sub-paths of each conductor on the metal slab, thereby obtaining the initial cutting path file of the metal slab.

[0048] In this embodiment, the processing of the first image is performed in the OpenCV tool, which provides a rich set of image processing functions that can quickly process the first image. The OpenCV tool is integrated and installed on a computer such as an industrial PC, which is connected to the control system and imaging device of the cutting machine.

[0049] The processing of the first image includes image preprocessing and contour extraction; wherein, image preprocessing includes grayscale processing, noise reduction processing and binarization processing to obtain a binarized grayscale image with clear contour boundaries; contour extraction includes edge detection to extract the contour boundaries in the binarized grayscale image through an edge detection algorithm to obtain an initial cutting path file containing the external actual sub-paths of each conductor 2 on the metal slab 1.

[0050] It is understandable that noise reduction processing includes, but is not limited to, various noise reduction methods such as Gaussian filtering or bilateral filtering; binarization processing uses Otsu's adaptive thresholding method, fixed thresholding method, or adaptive local thresholding method; edge detection uses Canny edge detection algorithm, Sobel algorithm, or Laplacian algorithm.

[0051] It should be noted that the first image, the binarized grayscale image, and the initial cutting path file exist as NumPy arrays. When the initial cutting path file needs to be saved and output, the initial cutting path file should be saved in DXF, SVG, or YC format.

[0052] S5. Perform coordinate matching between the initial cutting path file of metal slab 1 and the ideal cutting path file of metal slab 1 to obtain the spatial deviation between the inner endpoint of each external actual sub-path and the outer endpoint of the corresponding internal ideal sub-path.

[0053] It should be noted that the initial cutting path file and the ideal cutting path file contain multiple one-to-one corresponding reference points, and coordinate matching is performed through these reference points.

[0054] S6. If there is no spatial deviation between the inner endpoint of the actual external sub-path and the outer endpoint of the corresponding ideal internal sub-path, then the corresponding ideal internal sub-path is the optimal internal path. If there is a spatial deviation between the inner endpoint of the actual external sub-path and the outer endpoint of the corresponding ideal internal sub-path, then based on the coordinates of the inner endpoint of the actual external sub-path and the coordinates of the outer endpoint of the ideal internal pad segment, the transition path with the highest matching degree is automatically found in the preset transition path template library, and the optimal internal path is generated based on the transition path with the highest matching degree and the ideal internal pad segment.

[0055] In this embodiment, the method for automatically finding the transition path with the highest matching degree is as follows: traverse all transition paths in the transition path template library; use the Euclidean distance algorithm to calculate the first Euclidean distance between the outer endpoint of each transition path and the inner endpoint of the actual external sub-path, and the second Euclidean distance between the outer endpoint of each transition path and the outer endpoint of the corresponding inner pad segment ideal path, so as to obtain the sum of the Euclidean distances of each transition path; and select the transition path with the smallest sum of Euclidean distances as the transition path with the highest matching degree.

[0056] It should be noted that the sum of the Euclidean distances of the transition paths with the highest matching degree must not exceed the laser kerf width (i.e., the diameter of the laser spot); the laser kerf width is generally 0.1mm to 0.15mm (including the endpoints), and the specific width can be selected according to the actual situation.

[0057] Thus, when the sum of the Euclidean distances of the transition paths with the highest matching degree is 0, the transition path can perfectly connect the external actual sub-path and the corresponding ideal path of the inner pad segment; when the sum of the Euclidean distances of the transition paths with the highest matching degree is not 0, the diameter of the laser spot can be used to compensate for the deviation between the determined transition path and the endpoints of the external actual sub-path and the corresponding ideal path of the inner pad segment, ensuring that the subsequently cut internal actual sub-paths are continuous (i.e., the cut actual transition path connects with the actual path of the inner pad segment) and can be well connected with the corresponding external actual sub-path, so as to ensure the smooth cutting and separation of conductor 2.

[0058] S7. Perform secondary cutting on the metal blank after the initial cutting according to each optimal internal path to obtain each conductor.

[0059] Since the present invention obtains the optimal transition path based on the actual situation of the initial cutting and the ideal path matching of the corresponding inner pad segment, the transition path obtained by matching is used to compensate for and eliminate the position deviation caused by the actual external sub-path, thereby ensuring the cutting quality of the inner pad path segment, reducing or avoiding the shape and position deviation of the inner pad segment, and thus improving the accuracy of the relative position between the inner and outer pad segments, and improving the reliability of the subsequent stator winding.

[0060] In summary, this invention optimizes the traditional one-step conductor path cutting scheme into a two-step cutting scheme. The core of this two-step cutting scheme is to first cut the metal blank 1 according to the ideal external paths of each conductor, and then intelligently match a transition path to compensate for and eliminate the positional deviation caused by the actual cutting of the external paths based on the actual cutting situation of the external paths and the processing requirements of the ideal path of the corresponding inner pad segment. Subsequent cutting is then performed based on the matched transition path and the original ideal path of the inner pad segment to ensure the processing quality of the inner pad segment, thereby improving the accuracy of the relative position between the inner and outer pad segments. This is beneficial to ensuring the welding quality between the upper and lower conductors and improving the reliability of the subsequent stator winding.

[0061] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in the present invention should still be covered by the claims of the present invention.

Claims

1. A method of laser cutting a conductor for a disc stator winding, characterized by, The cutting method includes: S1. Obtain the ideal cutting path file for the metal slab; the ideal cutting path file for the metal slab includes the ideal cutting paths for each conductor. S2. Divide the ideal cutting path of each conductor into an external ideal sub-path and an internal ideal sub-path; wherein, the external ideal sub-path includes the ideal path of the outer pad segment, the ideal path of the outer bridging segment, the ideal path of the working segment, and the ideal path of the inner bridging segment connected in sequence; the internal ideal sub-path includes the ideal path of the inner pad segment. S3. Perform initial cutting of the metal slab based on the ideal external paths of each conductor, and obtain the first image of the metal slab after initial cutting. S4. Process the first image to extract the actual external sub-paths of each conductor on the metal slab, and then obtain the initial cutting path file of the metal slab. S5. Perform coordinate matching between the initial cutting path file and the ideal cutting path file of the metal slab to obtain the spatial deviation between the inner endpoints of each external actual sub-path and the corresponding outer endpoints of the internal ideal sub-path. S6. If there is no spatial deviation between the inner endpoint of the actual external sub-path and the outer endpoint of the corresponding ideal internal sub-path, then the corresponding ideal internal sub-path is the optimal internal path; if there is a spatial deviation between the inner endpoint of the actual external sub-path and the outer endpoint of the corresponding ideal internal sub-path, then based on the coordinates of the inner endpoint of the actual external sub-path and the coordinates of the outer endpoint of the ideal internal pad segment, the transition path with the highest matching degree is automatically found in the preset transition path template library, and the optimal internal path is generated based on the transition path with the highest matching degree and the ideal internal pad segment. S7. Perform secondary cutting on the metal blank after the initial cutting according to each optimal internal path to obtain each conductor.

2. The laser cutting method of a conductor for a disc stator winding according to claim 1, characterized by, The method for automatically finding the transition path with the highest matching degree is as follows: traverse all transition paths in the transition path template library; use the Euclidean distance algorithm to calculate the first Euclidean distance between the outer endpoint of each transition path and the inner endpoint of the actual external sub-path, and the second Euclidean distance between the outer endpoint of each transition path and the outer endpoint of the corresponding inner pad segment ideal path, so as to obtain the sum of the Euclidean distances of each transition path; and select the transition path with the smallest sum of Euclidean distances as the transition path with the highest matching degree.

3. A laser cutting method for a conductor used in a disc-type stator winding according to claim 1 or 2, characterized in that, The processing of the first image was performed using the OpenCV tool.

4. The laser cutting method for conductors used in disc stator windings according to claim 3, characterized in that, The processing of the first image includes image preprocessing and contour extraction; the image preprocessing includes grayscale processing, noise reduction processing and binarization processing; the contour extraction includes edge detection.

5. The laser cutting method for conductors used in disc stator windings according to claim 4, characterized in that, The noise reduction process employs Gaussian filtering or bilateral filtering.

6. The laser cutting method for a conductor used in a disc stator winding according to claim 4, characterized in that, The binarization process employs either the Otsu adaptive thresholding method, the fixed thresholding method, or the adaptive local thresholding method.

7. The laser cutting method for conductors used in disc stator windings according to claim 4, characterized in that, Edge detection uses the Canny edge detection algorithm, the Sobel algorithm, or the Laplacian algorithm.

8. The laser cutting method for conductors used in disc stator windings according to claim 4, characterized in that, Step S4 also includes saving and outputting the initial path cutting file, wherein the initial path cutting file is saved in DXF, SVG, or YC format.

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