JP6883969B2 - Defect detection system for rolled materials - Google Patents

Description

The present invention relates to a system for detecting defects formed on the surface of a rolled material such as a footboard.

Tracks for construction machinery and the like are constructed by connecting a large number of tracks. Each footboard is obtained by cutting a rolled material to a predetermined length and drilling a hole.
Defects generated during rolling or processing may remain on the surface of the footboard. Before incorporating it into the track, it was necessary to eliminate the flawed crawler plate as a defective product, but the workability was poor because it relied on a visual inspection by an inspector. In addition, there were cases where rust and scale could not be visually distinguished from surface flaws, and the flaws could not be detected reliably.

Patent Document 1 discloses a detection system using a photocutting method for detecting defects in a weld bead extending linearly. The detection system includes a sensor head that scans along the weld bead. The sensor head includes a light emitting unit that irradiates the surface of the work with band-shaped incident light orthogonal to the extending direction of the bead, and an imaging unit that captures the outline of the work surface drawn by the band-shaped incident light from a position away from the scanning direction. Have. Further, the detection system includes image processing means. This image processing means can recognize the three-dimensional shape of the bead from the image information of the contour of the surface sequentially input from the sensor head in accordance with the scanning, and can detect the defect.

Patent Document 2 discloses a detection system using the same optical cutting method as in Patent Document 1 in order to detect a defect on the lower surface of a work conveyed by a roller conveyor.

Japanese Unexamined Patent Publication No. 2013-213733 JP-A-2009-244162

In order to eliminate the above-mentioned inconvenience visually by the worker, it is conceivable to apply the detection systems of Patent Documents 1 and 2 to the detection of defects on the surface of the footboard. According to this detection system, the workability of defect detection is improved, and rust and scale can be distinguished from surface defects, and reliable surface defect detection can be expected. However, since the footboard has lugs (protrusions) protruding from the plate portion and has a complicated cross-sectional shape, it is difficult to detect defects on the entire surface of the footboard. The reason will be briefly explained. When the band-shaped incident light obtained by spreading the laser beam with a cylindrical lens is irradiated from directly above, it is possible to detect defects on the entire upper surface of the plate and the top surface of the lug, but it is not possible to detect defects on both sides of the lug. When the band-shaped incident light is irradiated from diagonally above the footboard, it is possible to detect flaws on one side of the lug, but not on the other side, and the plate portion where the band-shaped incident light is blocked by the lug. Defects in the upper surface area cannot be detected.

The present invention has been made to solve the above problems, and is used in a flaw detection system for detecting flaws on the surface of a plate portion and a rolled material having ridges formed on the plate portion.
A conveyor on which the rolled material is placed with the ridges facing up and conveyed in the longitudinal direction of the rolled material, and first, second, and third contour information acquisition means arranged above the conveyor, and defect determination. With means,
The first, second, and third contour information acquisition means are a light emitting portion that irradiates the surface of the rolled material with strip-shaped incident light intersecting the longitudinal direction of the rolled material, and the above-mentioned drawn by the strip-shaped incident light. Each has an imaging unit that images the contour of the surface of the rolled material.
The first contour information acquisition means obtains contour information of the upper surface of the plate portion and the top of the ridge on the surface of the rolled material by irradiating the strip-shaped incident light downward.
The second contour information acquisition means obtains contour information of one side surface of the ridge of the rolled material by irradiating the strip-shaped incident light diagonally downward from one side in a direction orthogonal to the transport direction.
The third contour information acquisition means obtains contour information on the other side surface of the ridge of the rolled material by irradiating the strip-shaped incident light diagonally downward from the opposite side of the second contour information acquisition means.
The defect determining means sequentially receives the contour information from the first, second, and third contour information acquisition means as the rolled material is conveyed by the conveyor, and the surface of the rolled material is based on the contour information. It is characterized in that the presence or absence of a flaw is determined.
According to the above configuration, since the surface defect of the rolled material is determined from the surface contour information obtained by the band-shaped incident light, the surface defect can be detected efficiently and surely. Further, since the contour information of the upper surface of the plate portion of the rolled material is acquired by the first contour information acquisition means and the contour information of both side surfaces of the ridge is acquired by the second and third contour information acquisition means, the ridge is provided. Surface defects can be detected even in rolled materials with complicated cross-sectional shapes.

Preferably, the second and third contour information acquisition means each have one sensor head, each of these sensor heads has the light emitting unit and the imaging unit, and the rolled material is subjected to the moving means. It is supported so that its position can be adjusted in the direction of approaching and separating.
According to the above configuration, surface defects of rolled materials having different widths can be detected by adjusting the position of the sensor head of the second and third contour information acquisition means.

The moving means for at least one sensor head of the second and third contour information acquisition means has an angle adjusting mechanism for adjusting the angle of the sensor head in the vertical direction on a plane orthogonal to the longitudinal direction of the rolled material. I have.
According to the above configuration, even when the rolled material has a plurality of ridges, one ridge does not block the irradiation of the band-shaped incident light to the other ridges by adjusting the angle of the sensor head. It is possible to detect flaws in the entire upper surface of the rolled material.

Preferably, the conveyor is composed of a roller conveyor and further includes a fourth contour information acquisition means, and the fourth contour information acquisition means is located below the rolled material and is rolled from between adjacent rollers of the roller conveyor. The lower surface of the material is provided with a light emitting portion that irradiates a band-shaped incident light intersecting the longitudinal direction thereof, and an imaging unit that images the contour of the lower surface of the plate portion of the rolled material drawn by the strip-shaped incident light. The means determines the presence or absence of flaws on the surface of the rolled material by taking into account the contour information of the lower surface of the plate portion of the rolled material.
According to the above configuration, it is possible to detect defects on both the upper and lower surfaces of the rolled material.

Preferably, further, a positioning plate extending along the transport direction of the roller conveyor is arranged on one side in the width direction of the roller conveyor, and the surface of the positioning plate facing the roller conveyor is provided as a reference surface. Then, one side edge portion of the rolled material in the conveyed state is brought into contact with the reference surface by the positioning means.
According to the above configuration, the rolled material can be positioned, and more reliable defect detection can be performed. It is preferable that the positioning plate is provided with a notch in the vicinity of the target measurement site so as not to interfere with the detection of defects in the target.

Preferably, the rolled material is a footboard, the footboard has at least one lug as the ridge, and one side edge of the plate is bent to the opposite side of the ridge. A gap is formed between one end surface of the roller and the positioning plate, and one side edge portion of the plate portion enters the gap and comes into contact with the reference surface of the positioning plate.
According to the above configuration, surface defects of the footboard can be detected, and one of the bent side edges can be arranged in the gap between one end surface of the roller and the positioning plate, so that the footboard can be stably conveyed. Can be done.

Preferably, the rolled material is a footboard, the footboard has at least one lug as the ridge, and the second and third contour information acquisition means each have one sensor head. The first and fourth contour information acquisition means each have two sensor heads separated from each other in the width direction of the roller conveyor, and each of these sensor heads has the light emitting unit and the imaging unit, and the first The sensor head on the positioning plate side of the fourth contour information acquisition means is in a fixed position, and the sensor head on the side opposite to the positioning plate of the first and fourth contour information acquisition means is moved in the vertical direction by the moving means. The sensor head of the second contour information acquisition means is movably supported by the moving means while being arranged on the positioning plate side, and is movably supported by the moving means to acquire the third contour information. The sensor head of the means is arranged on the opposite side of the positioning plate, and the moving locus is inclined so as to move upward from the positioning plate on a plane orthogonal to the longitudinal direction of the foot plate by the moving means. It is supported so that it can be moved along.
According to the above configuration, it is possible to detect surface defects of footboards having different widths and footboards having different lug heights.

Preferably, the moving means for supporting the sensor head on the side opposite to the positioning plate of the first contour information acquisition means moves away from the positioning plate as it goes upward on a plane orthogonal to the longitudinal direction of the foot plate. The sensor is moved in the vertical direction with a movement locus that is tilted in this way.

Preferably, the moving means that supports the sensor head of the third contour information acquisition means includes an angle adjusting mechanism that adjusts the angle of the sensor head in the vertical direction on a surface orthogonal to the longitudinal direction of the rolled material. ..

According to the present invention, even a rolled material having protrusions can efficiently and surely detect surface defects.

It is a side view of the defect detection system on the surface of a footboard which constitutes 1st Embodiment of this invention, and 3 sensor heads out of 6 sensor heads are omitted. FIG. 1 is a cross-sectional view taken along the line AA in FIG. It is a top view which shows only the main part structure of the defect detection system. It is an enlarged plan view which shows the state which the footboard is conveyed by the roller conveyor of the defect detection system, and the inclination of a roller is exaggerated. It is a block diagram which shows the flow of information in the defect detection system. It is a figure which shows typically the position of the sensor head and the band-shaped incident light which irradiates from these sensor heads at the time of detecting the surface defect of a single shoe (footboard) of a large size in the defect detection system. It is a figure which shows typically the position of the sensor head and the band-shaped incident light which irradiates from these sensor heads at the time of detecting the surface defect of a small size single shoe (footboard) in the defect detection system. It is a figure which shows typically the position of the sensor head and the band-shaped incident light which irradiates from these sensor heads at the time of detecting the surface defect of a triple shoe (footboard) in the defect detection system.

Hereinafter, a defect detection system for a footboard (rolled material) according to an embodiment of the present invention will be described with reference to the drawings. As shown in FIGS. 1 and 2, the flaw detection system includes a transport device 10 for transporting the footboard 50 in the longitudinal direction thereof, and a flaw detection device 20.

The transport device 10 is supported by a linearly extending support frame 11, a linear roller conveyor 12 (conveyor) horizontally supported on the upper portion of the support frame 11, and one side of the roller conveyor 12 in the width direction. It has a positioning plate 13 supported on the upper part of the frame 11, a motor 14 (see FIG. 1), and a timing belt mechanism 15 (see FIG. 2) that transmits the driving force of the motor 14 to the roller conveyor 12. There is.

As shown in FIGS. 1 and 3, the positioning plate 13 extends linearly in the longitudinal direction (conveying direction) of the roller conveyor 12 on one side in the width direction of the roller conveyor 12 and is fixed to the support frame 11. It is supported by a plurality of brackets 19. The surface of the positioning plate 13 facing the roller conveyor 12 is provided as a reference surface 13a.

As shown in FIGS. 1 and 3, the roller conveyor 12 has a large number of rollers 12a arranged at intervals in the transport direction. As shown in FIG. 2, each roller 12a is rotatably supported by a pair of bearings 12c fixed to the support frame 11 via a rotating shaft 12b.
As shown in FIGS. 2 and 3, the positioning plate 13 is separated from one end surface of the roller 12a via a gap 16.

As shown in an exaggerated manner in FIG. 4, the rotation axis L1 of the roller 12a is slightly inclined in the transport direction with respect to the normal line L2 of the reference surface 13 of the positioning plate 13. This inclination angle Θ is, for example, 1 °. Therefore, since the foot plate 50 to be conveyed receives a force toward the positioning plate 13, one side edge thereof always hits the reference surface 13a of the positioning plate 13 as shown in FIGS. Positioned in the direction. The positioning means is configured by the arrangement of the rollers 12a.

The defect detection device 20 is arranged in the middle of the roller conveyor 12, and is a support frame 21 and four sensor heads 22, 23, 24 supported by the support frame 21 and arranged above the roller conveyor 12. , 25, two sensor heads 26 and 27 supported by the support frame 21 and arranged below the roller conveyor 12, and a defect determining means 28 (see FIG. 5).

The support frame 11 of the transport device 10 and the support frame 21 of the defect detection device 20 are independent of each other, and the legs of these support frames 11 and 21 are made of rubber to block vibration transmission from the outside. It is installed on the floor or base via the materials 11a and 21a. Further, although not explicitly shown in FIG. 1, the motor 14 is installed in a support frame independent of the support frames 11 and 21.

Each of the sensor heads 22 to 27 is a light emitting portion 22a to 27a that emits a band-shaped incident light composed of laser light orthogonal to the transport direction (longitudinal direction of the footboard 50), and a rolled material 50 drawn from the band-shaped incident light. It has imaging units 22b to 27b that image the contour of the surface. The imaging units 22b to 27b are separated from the light emitting units 22a to 27a in the transport direction. In the figure, the band-shaped incident light from the light emitting units 22a to 27a is designated by the reference numeral S, and the imaging range of the imaging units 22b to 27b is indicated by the reference numeral R.

The sensor heads 22 and 23 (first contour information acquisition means) are arranged directly above the roller conveyor 12 at intervals in the width direction of the roller conveyor 12, and the light emitting portions 22a and 23a are worn directly below. The plate 50 is irradiated with band-shaped incident light.

As shown in FIG. 2, the sensor head 22 closer to the positioning plate 13 is fixed by the bracket 32.
The sensor head 23 farther from the positioning plate 13 is fixed to the rod of the uniaxial robot 33 (moving means) fixed to the support frame 21 via the bracket 33a, and can move in the vertical direction by driving the uniaxial robot 33. Is. The movement locus of the sensor head 23 by the uniaxial robot 33 is inclined at a relatively small angle so as to move away from the positioning plate 13 as it goes upward on a plane orthogonal to the transport direction (longitudinal direction of the footboard 50). .. As a result, the sensor 23 approaches the positioning plate 13 when it is in the lower position and moves away from the positioning plate 13 when it is in the upper position.

The sensor head 24 (second contour information acquisition means) is arranged on the positioning plate 13 side from the sensor heads 22 and 23, and the light emitting unit 24a irradiates the band-shaped incident light from diagonally above toward the foot plate 50. .. The sensor head 24 is fixed to the rod of the uniaxial robot 34 (moving means) fixed to the support frame 21 via the bracket 34a, and can be moved in the vertical direction by the uniaxial robot 34.

The sensor head 25 (third contour information acquisition means) is arranged on the opposite side of the sensor head 24 when viewed from the sensor heads 22 and 23, and irradiates the band-shaped incident light from diagonally above toward the footboard 50. The sensor head 25 is supported by the support frame 21 via the moving means 35. More specifically, the moving means 35 includes a uniaxial robot 35a, a moving table 35b moved by the uniaxial robot 35a, and a swivel robot 35d connected to the moving table 35b via an angle adjusting mechanism 35c. Have. The sensor head 25 is fixed to the swivel robot 35d.

The uniaxial robot 35a moves the moving table 35b along a moving locus inclined so as to move upward from the positioning plate on a plane orthogonal to the transport direction (longitudinal direction of the footboard 50). The sensor head 25 can be moved closer to or further away from the footboard 50 along an inclined movement locus, and its position can be adjusted. The angle adjusting mechanism 35c can adjust the angle of the sensor head 25 in the vertical direction on a plane orthogonal to the longitudinal direction of the footboard 50.

The sensor head 26 and the sensor head 27 (fourth contour information acquisition means) are arranged directly below the roller conveyor 12 so as to be separated from each other in the width direction of the roller conveyor 12, and the light emitting portions 26a and 27a are directed directly upward. The footboard 50 is irradiated with the band-shaped incident light.

The sensor head 26 closer to the positioning plate 13 is fixed to the support frame 21 by the bracket 36.
The sensor head 27 farther from the positioning plate 13 is fixed to the rod of the uniaxial robot 37 (moving means) fixed to the support frame 21 via the bracket 37a, and can be moved in the vertical direction by the uniaxial robot 37. ..

The flaw detection system having the above configuration can detect flaws on the surface of various footboards.
First, the inspection of the footboard 50, which is called a large size single shoe, will be described with reference to FIG. The footboard 50 has a plate portion 51 and a single lug 52 (protrusion). One side edge portion 51a of the plate portion 51 is bent to the opposite side of the lug 52. The lug 52 is formed in the vicinity of the bent side edge portion 51a.

As described above, the foot plate 50 is positioned in the width direction by the side edge portion 51a coming into contact with the reference surface 13a of the positioning plate 13 in the conveyed state of the foot plate 50. The side edge portion 51a enters the gap 16 between one end surface of the roller 12a and the positioning plate 13, whereby the foot plate 50 is stably supported by the roller conveyor 12. The same applies to other footboards described later.

As shown in FIG. 6, the sensor heads 22 and 23 irradiate the upper surface of the plate portion 51 with the band-shaped incident light S to acquire an image of the contour of the upper surface. The sensor heads 26 and 27 irradiate the lower surface of the plate portion 51 with the band-shaped incident light S to acquire an image of the contour of the lower surface. The sensor head 24 irradiates one side surface of the lug 52 with the band-shaped incident light S to acquire an image of the contour of the one side surface. The sensor head 25 irradiates the other side surface of the lug 52 with the band-shaped incident light S to acquire an image of the contour of the other side surface. An image of the contour of the top surface of the lug 52 can be acquired by the sensor head 22.

Since the width of the footboard 50 is wide, by setting the sensor head 23 in the upper position and the sensor head 27 in the lower position, the irradiation range of the band-shaped incident light S from the sensor heads 23 and 27 is widened, and the shoes are worn. The entire upper surface and lower surface of the plate 50 can be scanned.
Further, since the lug 52 is high, the sensor head 24 is set at an upper position so that a band-shaped incident light can be applied to a wide area on one side surface of the lug 52. Since the sensor head 25 has a larger inclination angle than the sensor head 24, it is possible to irradiate the entire other side surface of the lug 52 with the band-shaped incident light S even when the sensor head 25 is in an approaching position.

As shown in FIG. 5, the defect determining means 28 receives sequential contour image information from the sensor heads 22 to 27 as the footboard 50 is conveyed by the roller conveyor 12, and the surface of the footboard 50 is based on the contour image information. A three-dimensional image is calculated and displayed on the monitor display 41, and the presence or absence of a defect is determined based on the three-dimensional image. If it is determined that the product is non-defective without flaws, the footboard 50 is allowed to be transported along the conveyor line connected to the downstream side of the roller conveyor 12, and if it is determined that the product is defective with flaws, the payout device 42 Is operated to remove the footboard 50 from the conveyor line.

Next, as shown in FIG. 7, the inspection of the footboard 60, which is called a small size single shoe, will be described. Like the footboard 50, the footboard 60 has a plate portion 61 in which one side edge portion 61a is bent, and a lug 62 (protrusion) formed in the vicinity of the side edge portion 61a. There is. The width of the plate portion 61 is narrower than the plate portion 51 of the footboard 50, and the lug 62 is lower than the lug 52 of the footboard 50.

When inspecting the footboard 60, since the positions of the sensor heads 22 and 26 are fixed as compared with FIG. 6, the positions of the sensor heads 25 do not change, but the positions of the sensor heads 23, 24 and 27 change. For comparison, the positions of the sensor heads 23, 24, and 27 when inspecting the footboard 50 of FIG. 6 are shown by imaginary lines. Since the width of the plate portion 61 is narrow, the sensor head 23 is placed in the lower position and the sensor head 27 is placed in the upper position to narrow the irradiation range of the slits S of the sensor heads 23 and 27. The sensor head 23 is also approaching the footboard 60 in the horizontal direction. The sensor head 24 is in the lower position corresponding to the lower lug 62.
In this way, it is possible to obtain a contour image of the entire surface of the footboard 60, which is a small size single shoe. The operation of the defect determining means 28 is the same as described above.

Next, as shown in FIG. 8, the inspection of the footboard 70, which is called a triple shoe having a relatively large size, will be described. The footboard 70 has a plate portion 71 in which the side edge portion 71a is bent, and three lugs 72, 73, 74 (protrusions) arranged at intervals in the width direction of the plate portion 71. ing. These lugs 72, 73, 74 are lower than the lug 52 of the footboard 50.

As shown in FIG. 8, when the footboard 70 is inspected, the positions of the sensor heads 22, 24, 26 do not change as compared with FIG. 6, but the positions of the sensor heads 23, 25, 27 change. For comparison, the position of the sensor head 25 when inspecting the footboard 50 of FIG. 6 is shown by an imaginary line.

Since the sensor head 24 is in a high position, it is possible to irradiate a wide range, that is, all of one side surface of the three lugs 72, 73, 74 with the band-shaped incident light S. The band-shaped incident light S of the sensor head 24 can irradiate one side surface of the lug 73 without being blocked by the lug 72, and can irradiate one side surface of the lug 74 without being blocked by the lug 73.

Since the sensor head 25 is also in a high position and the height and angle can be adjusted, it is possible to irradiate a wide range, that is, all the other side surfaces of the three lugs 72, 73, 74 with the band-shaped incident light S. Further, since the sensor head 25 is adjusted so that the inclination angle can be reduced, the band-shaped incident light S of the sensor head 25 can irradiate the other side surface of the lug 73 without being blocked by the lug 74, and is blocked by the lug 73. The other side surface of the lug 72 can be irradiated without being damaged.

In the case of a triple shoe having a small size, the sensor heads 23, 24, 25, and 27 may be positioned in FIG. 7 and the angle of the sensor 25 may be adjusted in the same manner as in FIG.
When the footboard is a double shoe (a footboard with two lugs), the sensor head may be basically set in the same manner as the triple shoe.

As described above, by adjusting the positions of the sensor heads 23, 24, 25, and 27, it is possible to detect defects in the footboards of various shapes and sizes.
When a hole or the like is formed in the footboard, the defect determining means 28 does not perform image processing on this portion and masks it softly. Alternatively, pattern matching may be used to avoid detection of defects at this site.

The present invention is not limited to the above embodiment and can be used in various ways.
The angle of the sensor head 24 may be adjusted in the same manner as the sensor head 25.
The defect detection system of the present invention can be applied to rolled materials other than footboards.

The present invention can be applied to the detection of surface defects of a rolled material having ridges.

12 Roller conveyor (conveyor)
12a Roller 13 Positioning plate 13a Reference surface 16 Gap 22, 23 Sensor head (first contour information acquisition means)
24 Sensor head (second contour information acquisition means)
25 Sensor head (third contour information acquisition means)
26, 27 Sensor head (4th contour information acquisition means)
28 Defect determination means 33, 34, 37 Uniaxial robot (movement means)
35 Transportation means 35c Angle adjustment mechanism 50, 60, 70 Footboard (rolled material)
51, 61, 71 Plates 51a, 61a, 71a One side edge of the plate 52, 62, 72, 73, 74 lugs (protrusions)
S-band incident light

Claims (7)

In a defect detection system that detects defects on the surface of a footboard that is a rolled material,
The footboard has a plate portion and at least one lug formed on the plate portion as a ridge extending in the longitudinal direction of the plate portion, and one side edge portion in the width direction of the plate portion is the lug. It is bent to the opposite side,
A roller conveyor serving as a conveyor for conveying in the longitudinal direction of the crawler plate to the track shoe put face up the lug, first, second, third contour information acquisition means arranged above the roller conveyor And equipped with a defect judgment means
It said first, second, third contour information acquisition unit includes a light emitting unit for irradiating a band-shaped incident light which intersects the longitudinal direction of the crawler plate to the surface of the track shoe, the drawn by the strip incident light Each has an imaging unit that captures the contour of the surface of the footboard.
The first contour information acquisition means obtains contour information of the upper surface of the plate portion and the top portion of the lug among the surfaces of the footboard by irradiating the strip-shaped incident light downward.
The second contour information acquisition means obtains contour information of one side surface of the lug of the footboard by irradiating the band-shaped incident light diagonally downward from one side in a direction orthogonal to the transport direction.
The third contour information acquisition means obtains contour information on the other side surface of the lug of the footboard by irradiating the band-shaped incident light diagonally downward from the opposite side of the second contour information acquisition means.
The defect determining means receives the contour information sequentially from the first, second, and third contour information acquisition means as the footboard is conveyed by the roller conveyor, and the surface of the footboard is based on the contour information. to determine the presence or absence of flaws,
Further, a positioning plate extending along the transport direction of the roller conveyor is arranged on one side in the width direction of the roller conveyor, and a surface of the positioning plate facing the roller conveyor is provided as a reference surface.
The rotation axis of the roller is slightly inclined in the transport direction with respect to the normal of the reference surface of the positioning plate, and due to this inclined arrangement, the foot plate receives a force toward the positioning plate, and one of the above The side edge of the plate hits the reference surface of the positioning plate, whereby the foot plate is positioned in the width direction of the roller conveyor.
A recess whose upper side is open is formed by one end surface of the roller, a rotating shaft protruding from the end surface of the roller and supporting the roller, and the positioning plate, and one of the plate portions is formed in this recess. A flaw detection system, characterized in that the side edge portion of the roller enters and hits the reference surface of the positioning plate. Further comprising a fourth contour information acquisition means, the fourth contour information acquisition means, band-shaped and positioned below said crawler plate, intersects the adjacent rollers of the roller conveyor to the longitudinal direction on the lower surface of the track shoe It has a light emitting unit that irradiates incident light and an imaging unit that captures the outline of the lower surface of the plate portion of the footboard drawn by the band-shaped incident light.
Said flaw determining means, flaw detection system according to claim 1, characterized in that to determine the presence or absence of scratches on the surface of the track shoe in consideration also the contour information of the lower surface of the plate portion of the track shoe. The second and third contour information acquisition means each have one sensor head, and each of these sensor heads has the light emitting unit and the imaging unit, and is approached and separated from the footboard by the moving means. The flaw detection system according to claim 1, wherein the flaw detection system is supported so as to be position-adjustable in the direction of movement. The moving means for at least one of the second and third contour information acquisition means has an angle adjusting mechanism that adjusts the angle of the sensor head in the vertical direction on a plane orthogonal to the longitudinal direction of the footboard. The defect detection system according to claim 3, further comprising. The second, third contour information acquisition means each have one sensor head, the first, fourth contour information acquisition means, respectively have the two sensor heads spaced in the width direction of the roller conveyor to one another Each of these sensor heads has the light emitting unit and the imaging unit.
The sensor head on the positioning plate side of the first and fourth contour information acquisition means is in a fixed position, and the sensor head on the side opposite to the positioning plate of the first and fourth contour information acquisition means is a moving means. It is supported so that it can be moved in the vertical direction.
The sensor head of the second contour information acquisition means is arranged on the positioning plate side and is supported so as to be movable in the vertical direction by the moving means.
The sensor head of the third contour information acquisition means is arranged on the opposite side of the positioning plate, and is moved away from the positioning plate as it goes upward on a plane orthogonal to the longitudinal direction of the footboard by the moving means. The flaw detection system according to claim 2 , wherein the flaw detection system is supported so as to be movable along an inclined movement locus. The moving means for supporting the sensor head on the side opposite to the positioning plate of the first contour information acquisition means is inclined so as to move away from the positioning plate as it goes upward on a plane orthogonal to the longitudinal direction of the foot plate. The defect detection system according to claim 5 , wherein the sensor is moved in the vertical direction according to the moving locus. The moving means that supports the sensor head of the third contour information acquisition means is characterized by including an angle adjusting mechanism that adjusts the angle of the sensor head in the vertical direction on a surface orthogonal to the longitudinal direction of the footboard. The defect detection system according to claim 5 or 6.

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