Welded part inspection device and method

Abstract

Provided is a welded part inspection device with which it is simple to capture an image of a welded part, and the quality of a welded part can be easily and reliably determined. A welded part inspection device 1 for inspecting a welded part 5 of a stator 3 obtained by welding together adjacent coil ends 17 of a plurality of segment coils 10, said device comprising: an image-capture unit 23 which captures an image of a welded part 5; a monitor 25 which is positioned on the reverse side of the welded part 5 from the image-capture unit 23 in the image-capture direction and displays a background image 31 for the welded part 5; and a control unit 27 which causes the monitor 25 to display the background image 31, causes the image-capture unit 23 to capture an image of the welded part 5 together with the background image 31, and determines the shape of the welded part 5 in contrast with the background image 31, on the basis of the captured image.

Description

Weld inspection device and method

[0001] The present invention relates to an apparatus and method for inspecting welded portions of a stator in which adjacent coil ends of a plurality of segment coils are joined by welding.

[0002] Conventional weld inspection devices include, for example, those described in Patent Document 1, which are equipped with a camera, a light source, a wavelength conversion sheet, a light absorption means, and a control unit, and are used to inspect welds that connect adjacent coil ends of multiple segment coils.

[0003] In this weld inspection device, a light source irradiates blue light onto a wavelength conversion sheet located behind the weld, and the wavelength conversion sheet converts the irradiated blue light into another wavelength and reflects it, so that the reflected light irradiates the weld from the back side.

[0004] The camera captures an image of the weld from the front side while blocking the blue light via the light-absorbing means, with backlight irradiating the weld, allowing the control unit to easily and reliably determine the quality of the weld based on the highlighted outline of the weld.

[0005] However, the above-mentioned conventional weld inspection device requires complicated means and processes for capturing images of the weld.

[0006] Patent No. 6606202

[0007] The problem to be solved is that the means and process for imaging the welded portion have become complicated.

[0008] The present invention provides a weld inspection device for inspecting welds in a stator in which adjacent coil ends of a plurality of segment coils are joined by welding. The weld inspection device includes an imaging unit that images the weld, a monitor that is positioned on the opposite side of the imaging direction across the weld from the imaging unit and that displays a background image of the weld, a control unit that causes the monitor to display the background image and the imaging unit to image the weld together with the background image, and a shape determination unit that determines the shape of the weld based on the captured image by comparing it with the background image.

[0009] The present invention also provides a weld inspection method for inspecting welds in a stator in which adjacent coil ends of a plurality of segment coils are joined by welding. This weld inspection method includes displaying a background image of the weld on a monitor located on the opposite side of an imaging unit that images the weld, sandwiching the weld in an imaging direction, using the imaging unit to image the weld together with the background image, and determining the shape of the weld based on the image captured by the imaging unit by comparing it with the background image.

[0010] The weld inspection device and method of the present invention can easily and reliably determine whether the weld is good or bad while easily capturing an image of the weld.

[0011] FIG. 1 is a schematic perspective view showing a welded portion inspection apparatus according to a first embodiment of the present invention. FIG. 2 is a schematic plan view showing the welded portion inspection apparatus of FIG. 1. FIG. 3 is a schematic perspective view of a stator inspected by the welded portion inspection apparatus of FIG. 1. FIG. 4 is a schematic front view showing the relationship between a monitor and a welded portion of the welded portion inspection apparatus of FIG. 1. FIG. 5 is a schematic front view showing the relationship between a monitor and a welded portion of a welded portion inspection apparatus according to a second embodiment of the present invention. FIG. 6 is a schematic front view showing the relationship between a monitor and a welded portion of a welded portion inspection apparatus according to a third embodiment of the present invention. FIG. 7 is a schematic plan view showing the relationship between a monitor and a welded portion of a welded portion inspection apparatus according to a fourth embodiment of the present invention. FIG. 8 is a schematic plan view showing a welded portion inspection apparatus according to a fifth embodiment of the present invention.

[0012] The objective of easily and reliably determining whether a weld is good or bad while easily capturing an image of the weld has been achieved by using a monitor.

[0013] The weld inspection device 1 is a device that inspects the welds 5 of a stator 3 in which adjacent coil ends 17 of a plurality of segment coils 10 are joined by welding. The weld inspection device 1 includes an imaging unit 23, a monitor 25, a control unit 27, and a shape determination unit 27.

[0014] Imaging unit 23 captures an image of welded portion 5. Monitor 25 is located on the opposite side of imaging unit 23 in the imaging direction across welded portion 5, and displays a background image 31 of welded portion 5. Control unit 27 causes monitor 25 to display background image 31, and causes imaging unit 23 to capture an image of welded portion 5 together with background image 31. Shape determination unit 27 determines the shape of welded portion 5 by comparing it with background image 31 based on the image captured by imaging unit 23.

[0015] In one embodiment, control unit 27 may cause monitor 25 to display a plurality of background images 31 with different image configurations at least in the area adjacent to contour 5a of weld 5. In this case, control unit 27 causes imaging unit 23 to capture an image of weld 5 together with each of the plurality of background images 31. Shape determination unit 27 determines the shape of weld 5 based on a composite image 33 obtained by combining the plurality of captured images for the plurality of background images 31.

[0016] Furthermore, monitor 25 may display a plurality of divided background images 32 that are divided so as to respectively form the backgrounds of a plurality of welds 5. In this case, control unit 27 varies the image configurations of the plurality of divided background images 32, thereby making at least one of the plurality of welds 5 more visible than the other welds 5 as the imaging target.

[0017] The control unit 27 may also cause the monitor 25 to display a mark 35 for the welded portion 5 .

[0018] The monitor 25 may not only be flat, but also be curved in a planar view of the welded portion 5 and have a side portion 25a that faces the welded portion 5 in a direction intersecting the imaging direction.

[0019] The weld inspection method is a method for inspecting welds 5 of a stator 3 in which adjacent coil ends 17 of a plurality of segment coils 10 are joined by welding. In this weld inspection method, a background image 31 of the weld 5 is displayed on a monitor 25 located on the opposite side of the imaging direction from an imaging unit 23 that images the weld 5. The imaging unit 23 then images the weld 5 together with the background image 31, and the shape of the weld 5 is determined based on the captured image by comparing it with the background image 31.

[0020] In addition, in the weld inspection method, multiple background images 31 with different image configurations are displayed on the monitor 25 at least in the area adjacent to the outline 5a of the weld 5, and the imaging unit 23 images the weld 5 together with each of the multiple background images 31, and the shape of the weld 5 can be determined based on a composite image 33 obtained by combining the multiple captured images for the multiple background images 31.

[0021] In addition, in the weld inspection method, a divided background image 32 with a plurality of different image configurations, which is divided so as to form the background of each of the plurality of welds 5, may be displayed on the monitor 25, and at least one of the plurality of welds 5 may be made more visible than the other welds 5 as the imaging target.

[0022] Also, a mark 35 for the welded portion 5 may be displayed on the monitor 25 .

[0023] [Welded portion inspection device] Fig. 1 is a schematic perspective view showing a welded portion inspection device according to Example 1 of the present invention. Fig. 2 is a schematic plan view showing the welded portion inspection device of Fig. 1. Fig. 3 is a schematic perspective view of a stator inspected by the welded portion inspection device of Fig. 1.

[0024] 1 and 2, the weld inspection device 1 of this embodiment is a device that inspects the welds 5 of a stator 3. In this embodiment, the stator 3 to be inspected is configured, for example, as shown in Fig. 3. Note that the stator 3 is just one example, and any stator having similar welds 5 can be inspected.

[0025] The stator 3 constitutes a rotating electrical machine together with a rotor (not shown). The stator 3 has a stator core 7 and coils 9, as shown in FIGS.

[0026] The stator core 7 is formed into a cylindrical shape by stacking, for example, a plurality of plate-shaped core pieces. A plurality of axially penetrating slots 11 are provided at the inner periphery of the stator core 7 at intervals in the circumferential direction.

[0027] The coil 9 is configured to be wound in a wave-like manner around the inner circumference of the stator core 7. The coil 9 is made up of a plurality of segment coils 10. The plurality of segment coils 10 are attached to the stator core 7 in a combination in the circumferential direction.

[0028] Each segment coil 10 is formed by bending a rectangular wire made of an electrical conductor into, for example, a U-shape, particularly a hairpin shape, so that the segment coil 10 has a pair of legs 13 .

[0029] The pair of legs 13 are inserted into different slots 11 of the stator core 7. One end of the leg 13 protrudes from the end of the stator core 7 and is twisted to be inclined with respect to the axial direction of the stator core 7. The tip of the leg 13 is provided with a coil end 17 that extends along the axial direction of the stator core 7.

[0030] In FIG. 1, for ease of understanding, the entire leg portion 13 extending to the coil end 17 is aligned along the axial direction of the stator core 7.

[0031] The coil ends 17 are adjacent to the coil ends 17 of other segment coils 10 and are joined to the coil ends 17 of the adjacent segment coils 10 by welds 5. Multiple sets of joined coil ends 17 are arranged radially within each slot 11. In this embodiment, three sets of coil ends 17 are arranged radially. The welds 5 of these three sets are referred to as a parallel group 21.

[0032] Each welded portion 5 is formed by welding at the tip of a set of coil ends 17. The welding can be performed by, for example, laser welding, TIG welding, EB welding, etc. The welded portion 5 has a substantially spherical shape.

[0033] The weld inspection device 1 of this embodiment inspects the quality of the weld based on the shape of the weld 5.

[0034] As shown in FIGS. 1 and 2 , the weld inspection device 1 includes an imaging unit 23 , a monitor 25 , and a control unit 27 .

[0035] The imaging unit 23 is an imaging device such as a CCD camera, and captures images of the welds 5. In this embodiment, the imaging unit 23 simultaneously captures images of all three welds 5 in one parallel group 21. Note that the imaging unit 23 may simultaneously capture images of only a portion of the parallel group 21, for example, one or two welds 5.

[0036] The imaging unit 23 captures an image of the welded portion 5 from diagonally above. The imaging direction refers to the direction along the optical axis of the imaging unit 23, but this does not need to be interpreted strictly as long as it is the direction in which the imaging unit 23 is oriented for imaging. This imaging direction is preferably a direction oblique to the horizontal direction at an angle of 15 to 75 degrees, more preferably 30 to 60 degrees. The horizontal direction refers to the horizontal direction when the stator 3 is installed horizontally. In addition, in a plan view, the imaging direction is perpendicular to the arrangement direction of the welded portions 5 in the parallel group 21 to be imaged.

[0037] 4 is a front view showing the relationship between the monitor 25 and the weld 5 being imaged, and the composite image. Note that while FIG. 4 simultaneously illustrates the monitor 25 displaying background images 31 with different image configurations, which will be described later, in reality, a single monitor 25 displays multiple background images 31 shown in FIG.

[0038] 1, 2, and 4, the monitor 25 is a sheet-like display device such as an organic EL or micro LED. In this embodiment, the monitor 25 is formed in a rectangular sheet shape and is located on the opposite side of the imaging direction (referred to as the back side of the welds 5) from the imaging unit 23, with the welds 5 to be imaged sandwiched between them. As a result, the monitor 25 is located on the back side of all the welds 5 to be imaged. Note that the shape of the monitor 25 is not limited to a rectangle, and it does not have to be sheet-like, as long as it can be located on the back side of all the welds 5 to be imaged.

[0039] The position of this monitor 25 is within the gap 29 between adjacent parallel groups 21 in the circumferential direction of the stator core 7. When positioning the monitor 25 within the gap 29, the stator 3 is rotated and the monitor 25 is inserted radially or axially into the gap 29 on the back side of the welded portion 5 arranged at the imaging position. After imaging, the monitor 25 is retracted outside the gap 29, and after the stator 3 is rotated, the monitor 25 is inserted into the gap 29 on the back side of the welded portion 5 at the next imaging position.

[0040] The monitor 25 displays a background image 31 of the welded portion 5 on the rear side of the welded portion 5. Various background images can be used as the background image 31 as long as they can be contrasted with the welded portion 5 being imaged and enable the shape of the welded portion 5 to be determined. Preferably, the background image 31 can emphasize the outline 5a of the welded portion 5. The monitor 25 of this embodiment displays the background image 31 under the control of the control unit 27.

[0041] The control unit 27 is made up of a computer having a processor and memory, and controls the imaging unit 23 and the monitor 25. Through this control, the control unit 27 causes the monitor 25 to display a background image 31, and causes the imaging unit 23 to capture an image of the welded portion 5 together with the background image 31.

[0042] As for the display of the background image 31, a plurality of background images 31 with different image configurations are displayed on the monitor 25 at least in the area adjacent to the outline 5a of the weld 5. The image configurations are realized by colors, and the different image configurations differ in at least one of hue, brightness, and saturation, for example.

[0043] The area adjacent to the outline 5a of the weld 5 refers to an area in the background image 31 that surrounds the outline 5a and can be imaged by the imaging unit 23 together with the outline 5a of the weld 5. In order to differentiate the colors of these adjacent areas, in this embodiment, the entire area of ​​the monitor 25 is configured with a single-color background image 31, and the color of the single-color background image 31 is differentiated, as shown in Figure 4. The color of the background image 31 may be changed at predetermined time intervals.

[0044] Note that only the colors of the adjacent regions may be different in the background image 31. In this case, the adjacent regions may be extracted by image recognition based on the images of the background image 31 and the welded portion 5 captured by the imaging unit 23, and the colors of the extracted adjacent regions may be different.

[0045] The background image 31 may be fixed without changing the color. In this case, the background image 31 may be a combination of multiple colors instead of a single color. The background image 31 may be not only a still image but also a moving image. A moving image is an image in which not only the color but also the content such as the shape of the image is changed.

[0046] The control unit 27 causes the imaging unit 23 to capture images together with the display of the background images 31. That is, the control unit 27 causes the imaging unit 23 to capture images of the welded portion 5 together with each of the plurality of background images 31. The imaging may be performed in synchronization with the change in color of the background images 31.

[0047] The control unit 27 in this embodiment functions as a shape determination unit. The shape determination unit may be configured as a computer or the like separate from the control unit 27. The control unit 27 determines the shape of the welded portion 5 based on the captured image captured by the imaging unit 23 by comparing it with a background image 31. In this embodiment, the shape of the welded portion 5 is determined based on a composite image 33 obtained by combining a plurality of captured images with a plurality of background images 31.

[0048] The shape of the welded portion 5 can be determined not only by computer processing by the control unit 27 but also by an operator on a monitor for determination.

[0049] 1 and 2, in the weld inspection method, first, the monitor 25 is set relative to the stator 3. When setting the monitor 25, the stator 3 is placed in advance on a rotating table or the like and rotated to a desired position. This rotation positions the weld 5 of the parallel group 21 to be imaged at the image capture position.

[0050] The monitor 25 is inserted radially or axially into a gap 29 on the back side of the welded portion 5 arranged at the imaging position of the stator 3. The monitor 25 may be inserted by an appropriate robot arm or the like. However, the monitor 25 may also be inserted by moving the stator 3 side relatively while the monitor 25 is fixed.

[0051] Insertion of monitor 25 into gap 29 is completed by positioning monitor 25 with respect to welds 5. This positioning is performed so that monitor 25 is located behind all welds 5 in parallel group 21 that are the subject of imaging. At this time, background image 31 may be displayed on monitor 25, and imaging unit 23 may capture an image of the position of welds 5 relative to background image 31 on monitor 25. Based on this captured image, control unit 27 can determine the positioning state of monitor 25 and move monitor 25 to an appropriate position.

[0052] Once the monitor 25 is set up in this manner, imaging is performed to determine the shape of the welded portion 5. That is, the control unit 27 causes the monitor 25 to successively display a plurality of background images 31 of different colors as an image configuration at predetermined intervals, as shown in Fig. 4. In synchronization with the display of these different background images 31, the control unit 27 causes the imaging unit 23 to capture an image of the welded portion 5 together with each of the plurality of background images 31.

[0053] After the image is captured, the monitor 25 is retracted to the outside of the gap 29. Then, the stator 3 is rotated, and the monitor 25 is inserted to the rear side of the welded portion 5 at the next image capturing position.

[0054] Meanwhile, the control unit 27 determines the shape of the welded portion 5 based on the captured image by comparing it with the background image 31. In this embodiment, the control unit 27 determines the shape of the welded portion 5 based on a composite image 33 obtained by combining a plurality of captured images against a plurality of background images 31 of different colors.

[0055] The composite image 33 can be formed by any method, but is formed so as to emphasize the outline 5 a of the welded portion 5. The portion where the outline 5 a of the welded portion 5 is emphasized varies depending on the color of the background image 31. For this reason, the composite image 33 is formed, for example, by extracting the portion of each captured image where the outline 5 a of the welded portion 5 is most emphasized and combining these portions.

[0056] As a result, in the composite image 33, the outline 5a of the weld 5 is emphasized as a whole against the background image 31, making it clear. Note that the composite image 33 is binarized so that the background image 31 is white and the weld 5 is black. In this case, binarization is easy if the background image 31 of the captured images to be synthesized is blue, red, and green. However, the composite image 33 does not have to be binarized.

[0057] Based on the composite image 33, the control unit 27 can accurately determine the shape of the welded portion 5 and, based on this shape, accurately determine the quality of the welding. This quality determination can be made by comparing the shape of the welded portion 5 with a reference outline to determine whether it is within the range of shapes considered to be normal.

[0058] Alternatively, the shape of a normal product may be displayed on the background image 31 of the monitor 25, and the shape of the welded portion 5 being imaged may be used as a reference to determine whether it is within the range of normal product shapes. In this case, the normal product shape may be displayed superimposed on or parallel to the welded portion 5.

[0059] As described above, the weld inspection device 1 and method of this embodiment display background image 31 on monitor 25 located on the opposite side of the imaging direction from imaging unit 23, across weld 5 to be imaged. Imaging unit 23 images weld 5 together with this background image 31. The shape of weld 5 is then determined based on the captured image by comparing it with background image 31.

[0060] Therefore, in this embodiment, the image of the welded portion 5 can be easily captured using only the monitor 25 and the image capturing unit 23, and the shape of the welded portion 5 can be reliably recognized by comparing it with the background image 31 on the monitor 25. Based on the recognized shape of the welded portion 5, it is possible to easily and reliably determine whether the welded portion 5 is good or bad.

[0061] Furthermore, the weld inspection device 1 and method of this embodiment display on the monitor 25 a plurality of background images 31 that have different image configurations at least in the area adjacent to the outline 5a of the weld 5. The imaging unit 23 captures an image of the weld 5 together with each of these plurality of background images 31. The shape of the weld 5 is then determined based on a composite image 33 that is a composite of the captured images for the plurality of background images 31.

[0062] Therefore, in this embodiment, the portions in which the outline 5 a of the weld 5 is emphasized in each of the multiple captured images are extracted and these portions are combined to form a composite image 33. Therefore, in the composite image 33, the outline 5 a of the weld 5 is emphasized as a whole against the background image 31, making it clearer, and the quality of the weld 5 can be determined more easily and reliably.

[0063] 5 is a schematic front view showing the relationship between a monitor and a weld in a weld inspection device according to Example 2 of the present invention. Note that Example 2 has a basic configuration in common with Example 1, and therefore, the same reference numerals are used to designate components corresponding to those in Example 1, and redundant explanations will be omitted.

[0064] In the weld inspection device 1 and method of the second embodiment, a mark 35 for the weld 5 being imaged is displayed on the background image 31 of the monitor 25. This display can be performed under the control of the control unit 27 (see FIG. 1).

[0065] The shape and number of the mark 35 can vary depending on the application, but in this embodiment, one cross-shaped mark 35 is provided. The position of the mark 35 can vary depending on the application of the mark 35, but in this embodiment, it is displayed at the bottom right of the monitor 25 in Figure 5 for use in positioning the weld 5.

[0066] In the weld inspection device 1 and method of this embodiment, the positioning between the monitor 25 and the weld 5 can be performed using the mark 35. That is, the imaging unit 23 (see FIG. 1 ) captures an image of the weld 5 together with a background image 31 having the mark 35, and the monitor 25 is moved based on the captured image so that the mark 35 and the weld 5 have a predetermined positional relationship.

[0067] The monitor 25 may be moved by a robot arm or the like under the control of the control unit 27, or may be moved by an operator while recognizing the mark 35. Therefore, in this embodiment, the positioning between the monitor 25 and the stator 3 can be accurately performed not only by the control of the control unit 27 but also by the operator.

[0068] In this way, in this embodiment, it is possible to accurately position the monitor 25 and the welded portion 5. Furthermore, after the monitor 25 and the welded portion 5 are positioned, it is possible to accurately determine the position (coordinates) of the apex of the welded portion 5. As a result, it is also possible to determine the posture, such as the bending of the leg portion 13 of the segment coil 10, from the position of the apex of the welded portion 5.

[0069] Furthermore, in this embodiment, accurate positioning between the monitor 25 and the welds 5 allows for consistent display of the background image 31 contrasted with the welds 5 of the multiple parallel groups 21. As a result, in this embodiment, the shape of the welds 5 can be determined accurately and without variation, making it possible to more easily and accurately determine whether the welds 5 are good or bad.

[0070] In addition, the present embodiment can also achieve the same effects as the first embodiment.

[0071] 6 is a front view showing the relationship between a monitor and a weld in a weld inspection device according to Example 3 of the present invention. Since Example 3 has a basic configuration in common with Example 1, the same reference numerals are used to designate components corresponding to those in Example 1, and redundant explanations will be omitted.

[0072] In the weld inspection device 1 and method of the third embodiment, a plurality of divided background images 32 are displayed on the monitor 25, each divided to form the background of a plurality of welds 5. The image configurations of the plurality of divided background images 32 are then made different. This makes at least one of the plurality of welds 5 the object of imaging more visible than the other welds 5. The display of the divided background images 32 and the change of the image configuration can be controlled by the control unit 27 (see FIG. 1 ).

[0073] Divided background image 32 can be formed through image processing. Specifically, after monitor 25 and welded portion 5 are positioned, imaging unit 23 (see FIG. 1 ) captures an image of background image 31 and welded portion 5. Based on this captured image, control unit 27 recognizes multiple regions on monitor 25 that include each welded portion 5.

[0074] The control unit 27 displays divided background images 32 for each of these areas of the monitor 25. The weld 5 being imaged is made visible by changing the color of the image configuration of the divided background image 32. Making it visible means making it easier to recognize.

[0075] In this embodiment, the brightness of the divided background image 32 is changed as a color change. Specifically, the brightness of the divided background image 32 for the weld 5 being imaged is increased, and the brightness of the divided background image 32 for the remaining welds 5 is decreased.

[0076] Therefore, the weld inspection device 1 and method of the present embodiment make it possible to separately image the welds 5 to be imaged. In addition, the present embodiment can also achieve the same effects as those of the first embodiment.

[0077] 7 is a schematic plan view showing the relationship between a monitor and a weld in a weld inspection device according to Example 4 of the present invention. Since Example 4 has a basic configuration in common with Example 1, the same reference numerals are used to designate components corresponding to those in Example 1, and redundant explanations will be omitted.

[0078] In the weld inspection device 1 and method of this embodiment, the monitor 25 is bent in a plan view with respect to each weld 5 and has a side 25a that faces the weld 5 in a direction intersecting the imaging direction. The intersecting direction is not limited to a perpendicular direction but also includes a direction intersecting obliquely.

[0079] The monitor 25 in this embodiment has a planar shape that is curved like an arc, but the monitor 25 may have other planar shapes such as a V-shape or a channel shape.

[0080] In this embodiment, the background image 31 (see FIG. 4, etc.) can be displayed not only from the rear side of each weld 5 but also from the side. Therefore, in this embodiment, the shape of the weld 5 can be more reliably recognized in comparison with the background image 31 on the monitor 25. As a result, the quality of the weld 5 can be more easily and reliably determined.

[0081] 8 is a schematic plan view showing a weld inspection device according to a fifth embodiment of the present invention. Since the fifth embodiment has a basic configuration in common with the first embodiment, the same reference numerals are used to designate components corresponding to those in the first embodiment, and redundant explanations will be omitted.

[0082] The weld inspection device 1 of this embodiment is designed to capture images of the front and back shapes of a weld 25, and is provided with a pair of monitors 25 and a pair of imaging units 23. The rest is the same as in the first embodiment.

[0083] The pair of monitors 25 each have the same configuration as the monitor 25 of Example 1. These monitors 25 are arranged in the same gap 29 between adjacent parallel groups 21 in an opposite orientation, with their back surfaces, which do not display the background image 31, facing each other.

[0084] As a result, one of the monitors 25 is disposed facing one side in the circumferential direction and is located on the back side of the welded portion 5 of one adjacent parallel group 21 as the imaging target. The other of the monitors 25 is disposed facing the other side in the circumferential direction and is located on the back side of the welded portion 5 of the other adjacent parallel group 21 as the imaging target.

[0085] The pair of monitors 25 do not need to be positioned in the same gap 29 or have their back surfaces facing each other. In other words, it is sufficient that one of the monitors 25 is disposed facing one side in the circumferential direction and the other monitor 25 is disposed facing the other side in the circumferential direction.

[0086] Each of the pair of imaging units 23 has the same configuration as the imaging unit 23 of Example 1, and images the welded portions 5 of adjacent parallel groups 21 from one side and the other side in the circumferential direction with the pair of monitors 25 as the background. As a result, one of the pair of imaging units 23 images the welded portions 5 from the front side, and the other of the pair of imaging units 23 images the welded portions 5 from the back side.

[0087] Therefore, in this embodiment, it is possible to reliably recognize the shapes of the front and back of the welded portion 5, and more reliably determine whether the welded portion 5 is good or bad. In addition, this embodiment can also achieve the same effects as in the first embodiment.

[0088] REFERENCE SIGNS LIST 1 Welded part inspection device 3 Stator 5 Welded part 17 Coil end 23 Imaging unit 25 Monitor 25a Side part 27 Control unit (shape determination unit) 31 Background image 33 Composite image 35 Mark

Claims

1. A weld inspection device for inspecting welds of a stator in which adjacent coil ends of a plurality of segment coils are joined by welding, comprising: an imaging unit that images the welds; a monitor that is positioned on the opposite side of the imaging direction across the welds from the imaging unit and displays a background image of the welds; a control unit that causes the monitor to display the background image and the imaging unit to image the welds together with the background image; and a shape determination unit that determines the shape of the welds by comparing the captured image with the background image.

2. A weld inspection device as claimed in claim 1, wherein the control unit causes the monitor to display a plurality of background images with different image configurations at least in the area adjacent to the contour of the weld, and causes the imaging unit to capture images of the weld together with each of the plurality of background images, and the shape determination unit determines the shape of the weld based on a composite image obtained by combining a plurality of captured images relative to the plurality of background images.

3. A weld inspection device as claimed in claim 1, wherein the control unit causes the monitor to display a plurality of divided background images which are divided so as to respectively constitute the backgrounds of a plurality of the welds, and by varying the image configurations of the plurality of divided background images, at least one of the plurality of welds is made more visible as the imaging target than the other welds.

4. A weld inspection device according to any one of claims 1 to 3, wherein said control unit causes said monitor to display a mark for said weld.

5. A weld inspection device according to any one of claims 1 to 3, wherein the monitor is bent in a plan view of the weld and has a side portion facing the weld in a direction intersecting the imaging direction.

6. A weld inspection method for inspecting a weld of a stator in which adjacent coil ends of a plurality of segment coils are joined by welding, comprising the steps of: displaying a background image of the weld on a monitor located on the opposite side of the imaging direction of the weld from an imaging unit that images the weld; imaging the weld together with the background image with the imaging unit; and determining the shape of the weld based on the captured image by comparing it with the background image.

7. A weld inspection method according to claim 6, comprising the steps of: displaying on said monitor a plurality of background images with different image configurations at least in an area adjacent to the contour of said weld; capturing images of said weld together with each of said plurality of background images with said imaging unit; and determining the shape of said weld based on a composite image obtained by combining the captured images for said plurality of background images.

8. A weld inspection method as claimed in claim 7, comprising displaying on the monitor a plurality of divided background images with different image configurations, each divided to form a background for each of the plurality of welds, and imaging at least one of the plurality of welds to make it more visible than the other welds.

9. A weld inspection method according to claim 7 or 8, further comprising displaying a mark for the weld on the monitor.

Images