JP6321709B2 - Surface wrinkle inspection method - Google Patents

Description

  The present invention relates to a surface flaw inspection method for inspecting a surface flaw of an object to be inspected comprising a bar shape including steel bars.

  Conventionally, as a method for inspecting wrinkles on the surface of an object to be inspected that includes a bar shape including a steel bar, an inspector has generally performed it visually or by palpation. However, such an inspection method has a problem that there are individual differences, variation in inspection accuracy is large, and a certain inspection result cannot be obtained. Therefore, a nondestructive inspection method such as leakage magnetic flux or overflow deep damage is known so that a constant inspection result can be obtained.

  However, since this nondestructive inspection method is limited by the mechanical structure, there is a problem that it is not possible to find a fine wrinkle on the surface of the drawn and peeled steel bar that does not allow fine wrinkles. Therefore, in order to find such minute wrinkles, the object is irradiated with light, the reflected light from the surface of the object is received by an imaging camera, and the amount of light is measured to measure the surface of the object. An invention of detecting the presence or absence of wrinkles is known (for example, see Patent Document 1).

JP 2004-163176 A

  However, since the reflected light from the surface of the object to be inspected is direct light (light whose relative relationship with respect to the propagation direction of light does not change), depending on the light irradiation direction and irradiation solid angle, and the observation direction and observation solid angle, The apparent brightness of the surface of the object to be inspected has changed greatly, and it has been difficult to determine whether it is a flaw even if the amount of light is measured, and it is difficult to obtain a certain inspection result.

  In view of the above problems, an object of the present invention is to provide a surface wrinkle inspection method that can stably detect the presence or absence of wrinkles on the surface of an object to be inspected in a rod shape.

  The object of the present invention is achieved by the following means. In addition, although the code | symbol in a parenthesis attaches the referential mark of embodiment mentioned later, this invention is not limited to this.

According to the surface flaw inspection method of claim 1, the step of rotating the inspection object (K) having a rod shape by a predetermined number of times at a predetermined position by the rotating means (see the rotation driving mechanism 3) (step S1 shown in FIGS. 5 and 9). , Step S3, steps S11 and S13 shown in FIG. 9),
An illumination bar in which a plurality of light emitting elements (LEDs) are evenly arranged so that the brightness of the inspection object (K) is divided with the axis (O2) direction of the inspection object (K) rotating as a boundary. Acrylic round bar that collects and amplifies diffused light diffused from the LED illumination bar 40 (see LED illumination bar 40) and the illumination bar (see LED illumination bar 40) and emits strip-shaped light (LIC) in which light and dark light appear alternately A step of irradiating the object to be inspected (K) with the band-shaped light (LIC) by the light irradiation means (see LED illumination device 4C) configured by (41);
Step of imaging the object to be inspected (K) that has received the band-like light (LIC) irradiated by the light irradiation means (refer to the LED illumination device 4C) by the imaging means (refer to the line scan camera 5) (FIGS. 5 and 5) 9 and step S12 shown in FIG. 9),
A step (see step S5 shown in FIG. 5 and FIG. 9) of integrating the density amount in units of one pixel based on the image picked up by the image pickup means (see the line scan camera 5) by the image analysis means (see the CPU 60);
Judgment means (see CPU 60) for determining the presence or absence of wrinkles (Ka) on the surface of the object (K) based on whether or not the accumulated density amount by the image analysis means (see CPU 60) exceeds a predetermined threshold value. (See step S6 shown in FIG. 5 and FIG. 9).

According to a second aspect of the present invention, in the surface flaw inspection method according to the first aspect, the band-shaped light (LIC) irradiated by the light irradiation means (see the LED lighting device 4C ) is from one direction. It is characterized by being irradiated only.

On the other hand, according to a third aspect of the present invention, in the surface flaw inspection method according to the first aspect, the light irradiation means (refer to the LED lighting device 4C) is a first light irradiation means (first LED lighting device 4A). And a second light irradiation means (refer to the second LED illumination device 4B),
The band-shaped light (LIC) irradiated by the first light irradiation means (see the first LED illumination device 4A) is irradiated only from one direction,
The band-shaped light (LIC) irradiated by the second light irradiation means (see the second LED illumination device 4B) is irradiated only from another direction different from the one direction.

  According to a fourth aspect of the present invention, in the surface flaw inspection method according to any one of the first to third aspects, the imaging means (see the line scan camera 5) is a line scan camera (5). It is characterized by being.

  Next, effects of the present invention will be described with reference numerals in the drawings. In addition, although the code | symbol in a parenthesis attaches the referential mark of embodiment mentioned later, this invention is not limited to this.

According to the first aspect of the present invention, the inspection object (K) made of a rod shape is rotated a predetermined number of times at a predetermined position by the rotating means (see the rotation drive mechanism 3), and the inspection object (K) made of the rotating rod shape is obtained. ) By the light irradiation means (see LED illumination device 4C) so that the brightness of the inspection object (K) is divided with the axis (O2) direction of the inspection object (K) as a boundary. In addition, since the band-like light (LIC) in which light and dark light alternately appear is irradiated, when the eyelid (Ka) is formed on the object to be inspected (K), the eyelid (Ka) is any of its axis ( O2) is located in the dark area. As a result, if the inspection object (K) that has received the band-like light (LIC) emitted from the light irradiation means (see the LED illumination device 4C) is picked up by the imaging means (see the line scan camera 5), 疵 (Ka ) Portion is brightly imaged. However, an image obtained by brightly capturing the wrinkle (Ka) portion is analyzed by image analysis means (see CPU 60), and the presence or absence of wrinkles (Ka) on the surface of the inspection object (K) is determined based on the analysis result. If the determination is made by means (see the CPU 60), the presence or absence of wrinkles (Ka) can be accurately determined.

Therefore, according to the present invention, it is possible to stably detect the presence or absence of wrinkles on the surface of the inspection object having a rod shape. Furthermore, according to the present invention, when the object to be inspected (K) is irradiated with strip-shaped light (LIC) in which light and dark light appear alternately , wrinkles (Ka) are generated in the object to be inspected (K). Then, local distortion occurs, and the wrinkle (Ka) portion can be captured more clearly by the imaging means (see the line scan camera 5). That is, if wrinkles (Ka) are generated in the inspected object (K), the specular reflection angle of light (LIC) changes. Therefore, when the change is captured by the imaging means (see the line scan camera 5), Local distortion occurs in the band-shaped light (LIC). Therefore, the heel (Ka) portion can be captured more clearly by the imaging means (see the line scan camera 5).

According to the invention of claim 2, since the strip-shaped light (LIC) irradiated by the light irradiation means (refer to the LED lighting device 4C) is irradiated only from one direction, the scattered light is clearly defined. Therefore, the shading can be clarified.

On the other hand, according to the invention of claim 3, even if the wrinkle (Ka) of the object to be inspected (K) is a very gentle and shallow wrinkle, two light irradiation means (see LED lighting device 4C) are provided, Since the object-to-be-inspected (K) is irradiated with strip-shaped light (LIC) from different directions, the ridge (Ka) part is brightly illuminated by any of the strip-shaped light (LIC) , and thus the brightly illuminated light. The eyelid (Ka) portion can be imaged by the imaging means (see the line scan camera 5). Thereby, even if the wrinkle (Ka) of the inspection object (K) is a very gentle and shallow wrinkle, the presence or absence of the wrinkle (Ka) can be accurately determined.

  On the other hand, since the line scan camera (5) is used as the imaging means (see the line scan camera 5), the invention according to claim 4 is suitable for imaging the rod-shaped inspection object (K). .

It is a front view of the surface flaw inspection apparatus concerning a 1st embodiment of the present invention. It is a top view of the surface flaw inspection apparatus which concerns on the same embodiment. It is a schematic block diagram of the surface flaw inspection apparatus which concerns on the same embodiment. (A) is explanatory drawing which shows the state which the light irradiated from the LED illumination apparatus which concerns on the embodiment is scattered by the wrinkles formed in the to-be-inspected object, (b) is the light irradiated from the LED illumination apparatus FIG. 2 is an explanatory diagram showing a state where a bright field region which is a bright region and a dark field region which is a dark region are formed on the surface of the inspection object with the axis of the inspection object as a boundary. It is explanatory drawing which shows that a blind spot generate | occur | produces when light is irradiated from a direction. It is a flowchart figure which shows the processing content of the program stored in ROM of the image analysis control apparatus which concerns on the embodiment. (A) is an explanatory diagram showing binarization of an image captured by the line scan camera according to the embodiment on a pixel-by-pixel basis and binarization, and (b) is a predetermined threshold value. It is explanatory drawing which shows that the predetermined location exceeds. It is an example of a screen when image processing is performed on a part where wrinkles are generated on the inspection object. It is a schematic block diagram of the surface flaw inspection apparatus which concerns on 2nd Embodiment of this invention. It is a flowchart figure which shows the processing content of the program stored in ROM of the image analysis control apparatus which concerns on the embodiment. It is explanatory drawing which shows the state by which light is irradiated to the to-be-inspected object from the LED lighting apparatus which concerns on other embodiment.

<First Embodiment>
Hereinafter, a first embodiment of a surface flaw inspection apparatus relating to a surface flaw inspection method of the present invention will be specifically described with reference to FIGS. In addition, in the following description, when showing the direction of up, down, left and right, it means up, down, left and right when viewed from the front of the figure.

  As shown in FIG. 1, the surface flaw inspection apparatus 1 includes a support frame 2, a rotation drive mechanism 3 fixed to the support frame 2, an LED illumination device 4 fixed to the support frame 2, and The line scan camera 5 fixed to the support frame 2 and the image analysis control device 6 are mainly configured.

  As shown in FIG. 2, the support frame 2 includes a pair of a bottom plate 20 that is rectangular in plan view and a long rectangular shape in plan view that is fixed so as to be parallel to each other vertically on the bottom plate 20. The frame 21, the standing frame body 22 (see FIG. 1) that is erected on the frame body 21 at two predetermined intervals, and the standing frame bodies 22 that are spaced apart in the vertical direction are placed side by side. The horizontal frame 23 is constructed by a horizontal frame 23 and a pair of fixed frames 24 projecting from the horizontal frame 23 toward the center of the bottom plate 20.

  On the other hand, as shown in FIG. 1, the rotation drive mechanism 3 includes a servo motor 30 and a pair of rotating units 31. As shown in FIG. 1, the servo motor 30 is erected and fixed on the bottom plate 20, and is driven or stopped in response to a command from the image analysis control device 6. The servo motor 30 can output an encoder that can detect the motor position to the image analysis control device 6 (see FIG. 1).

  On the other hand, as shown in FIG. 2, the rotating portion 31 has a rod shape whose one end (upper side in the drawing) is rotatably attached and fixed to a fixing plate 31 a erected on the middle portion of the frame body 21 located on the upper side in the drawing. The shaft portion 31b, and a plurality of rollers 31c rotatably attached to the shaft portion 31b with a predetermined interval. As shown in FIG. 1, the pair of rotating units 31 configured in this way is connected to the servo motor 30 via the belt B, and the pair of rotating units 31 via the belt B when the servo motor 30 is driven to rotate. The rotating unit 31 rotates.

  Thus, on the pair of rotating parts 31 configured as described above, as shown in FIG. 1 and FIG. 2, a test object K made of a bar shape including a bar steel conveyed from a conveyance line (not shown) is placed. Then, when the servo motor 30 is driven to rotate, the pair of rotating portions 31 rotate via the belt B, and thus the inspection object K rotates in the direction of the arrow Y1 shown in FIG.

  The LED illumination device 4 is provided with a variable light source amplifier for LED illumination (not shown) so that a sufficient amount of light can be emitted. As shown in FIGS. 1 and 2, such an LED lighting device 4 has an arcuate movable support frame 24a provided on the lower side of the fixed frame 24 located on the right side of the drawing via a support shaft 24a1. It is attached and fixed so that light can be irradiated to the inspection object K from the upper right to the lower left. Specifically, as shown in FIG. 2, the LED lighting device 4 has a rectangular rear end portion 4 a attached to and fixed to a support shaft 24 a 1 and a front end portion 4 b made of a long bar, as shown in FIG. Inside, a white LED 4b1 made of a long bar as shown in FIG. 4A is provided. The white LED 4b1 is irradiated with the light LI only from one direction (in the drawing, the diagonally left direction). A directional film 4b2 is attached as shown.

  Thus, as shown in FIG. 3, the LED illumination device 4 configured in this manner has a horizontal distance l1, a height h from the center line O1 of the inspection object K, and a center line O1 of the inspection object K. It is arranged at a position where the inclination angle θ1 (θ1 <90 °) as a base point and the irradiation distance L of the light LI to the center line O1 of the inspection object K are set. Thereby, when the light LI is irradiated from the LED illumination device 4, as shown in FIG. 4B, the bright field region K1 that is a bright region of the inspection object K with the axis O2 of the inspection object K as a boundary. As a result, a dark field region K2, which is a dark region, is formed. At this time, since the inspection object K is rotated in the direction of the arrow Y1 shown in FIG. 1 by the rotational drive of the servo motor 30, when the eyelid Ka is formed on the inspection object K, the bright field region K1疵 Ka is located at the boundary with the dark field region K2.

  Here, when the eyelid Ka is formed on the inspection object K, as shown in FIG. 4A, when the light LI is irradiated onto the eyelid Ka, the light LI is scattered and the scattered light LIa is generated. At this time, if the eyelid Ka of the inspected object K is located in the dark field region K2, the eyelid Ka portion of the inspection object K becomes brighter, so that the eyelid Ka is compared with other parts by the line scan camera 5. A bright image is taken. In addition, this wrinkle Ka includes all wrinkles determined to be defective such as surface wrinkles, scratches, scratches, dents, dents, and the like.

  Incidentally, when such scattered light LIa is to be accurately captured by the line scan camera 5, it is necessary to appropriately set the distance between the inspection object K and the LED illumination device 4. That is, when the scattering coefficient is R, the volume of the scattering region is V, and the beam speed of the irradiated light is Io, the scattering intensity Is is expressed by the following equation.

  From Equation 1, it can be seen that the scattering intensity Is is inversely proportional to the square of the distance L (see FIG. 3). Therefore, if the scattered light LIa is to be accurately captured by the line scan camera 5, it is necessary to appropriately set the distance between the inspection object K and the LED illumination device 4. Therefore, the LED lighting device 4 shown in the present embodiment is arranged at a position as shown in FIG.

  In addition, when the luminance that changes the light propagation direction of the light LI irradiated from the LED illumination device 4 on the surface of the inspection object K is Ld, the luminance of the irradiation light is Li, and the reflectance is ρ, the inspection object The luminance Ld, which is a change in the light propagation direction on the surface of K, is expressed by the following equation.

  Further, when the luminance that changes the propagation direction of light on the surface of the inspection object K in the scattered light LIa is Ls, the point on the surface of the inspection object K is P, and the scattering rate is σ, it is expressed by the following equation. The

  From the above equations, it can be seen that the luminance that changes the light propagation direction on the surface of the inspection object K is closely related to the luminance, reflectance, and scattering rate of the irradiated light. In this regard, when only the white LED 4b1 is used without using the directional film 4b2, when a cold-drawn / peeled steel bar having a high reflectivity is used as the inspection object K, the scattered light of the surface with a metallic luster is scattered. Is difficult to capture. Therefore, in the present embodiment, the directional film 4b2 is used, and the light LI is irradiated only from one direction (in the illustration, the left oblique direction), thereby clarifying the scattered light, and FIG. 4 (b). As shown in the figure, the shade of 疵 Ka is made clear.

  As shown in FIG. 4C, the directivity film 4b2 may be irradiated with the light LI from two directions (left and right oblique directions in the drawing). However, in this case, a blind spot S is generated or scattered. There is a high possibility that the light interferes and the shade of 疵 Ka (see FIG. 4B) cannot be clarified. Therefore, it is preferable to use the directional film 4b2 that is irradiated with the light LI only from one direction.

  As shown in FIGS. 1 and 2, the line scan camera 5 has an arcuate movable support frame 24a provided at a lower portion of a fixed frame 24 whose rear end portion 5a is located on the left side of the figure via a support shaft 24a1. It is attached and fixed so that the inspection object K can be imaged from the oblique direction to the right from the camera lens side of the tip 5b. As described above, the line scan camera 5 is intended to image the eyelid Ka of the inspection object K, and therefore, it is necessary to image the scattered light LIa. It is not arranged, but is arranged at a position where the inspection object K can be imaged from the right oblique direction. Specifically, as shown in FIG. 3, the horizontal distance l2, height h from the center line O1 of the inspection object K, and the inclination angle θ2 (θ1 <θ1) with the center line O1 of the inspection object K as the base point. 90 °), a focal distance f to the center line O1 of the inspection object K, and a working distance WD from the line scan camera 5 to the inspection object K.

  By the way, this working distance WD is expressed by the following expression when the magnification (camera pixel size / pixel resolution) of the line scan camera 5 is M.

  In the present embodiment, an example in which the inspected object K is imaged using the line scan camera 5 is shown, but the present invention is not limited thereto, and an area sensor camera may be used. However, since the area sensor camera has a long integration time and requires a shutter, the area sensor camera is not suitable for imaging a rotating rod-shaped inspection object K. Therefore, it is preferable to use a line scan camera.

  The image analysis control device 6 analyzes the image of the inspection object K picked up by the line scan camera 5, determines the presence / absence of 疵 Ka (see FIG. 4B) of the inspection object K, and servo motor 30 drive is controlled. Specifically, as shown in FIG. 3, processing is performed by the CPU 60, a ROM 61 storing a program for analyzing the image and determining the presence or absence of 疵 Ka, and a program for controlling the drive of the servo motor 30, and the CPU 60. A RAM 62 for temporarily storing data, a display unit 63 such as a liquid crystal display, and an I / O 64 for inputting / outputting data are configured.

  Here, the processing contents of the program stored in the ROM 61 of the image analysis control device 6 will be described with reference to FIG.

  When the inspection object K having a bar shape including a steel bar conveyed from a conveyance line (not shown) is placed on the pair of rotating portions 31 (see FIGS. 1 to 3), the CPU 60 drives the servo motor 30. The command signal to command is output to the servo motor 30 via the I / O 64. In response to this, the servo motor 30 is driven to rotate, so that the inspection object K rotates in the direction of the arrow Y1 via the belt B as shown in FIG. 1 (step S1).

  Next, the CPU 60 acquires an image of the inspection object K rotated in the direction of the arrow Y1 captured by the line scan camera 5 via the I / O 64 (step S2). The acquired image is temporarily stored in the RAM 62.

  Next, the CPU 60 acquires an encoder capable of detecting the motor position output from the servo motor 30 via the I / O 64, and confirms whether the servo motor 30 has been rotationally driven a predetermined number of times (for example, twice) ( Step S3). If it has not been rotationally driven a predetermined number of times (step S3: NO), the process returns to step S2, and if it has been rotationally driven a predetermined number of times (step S3: YES), the process proceeds to step S4.

  Next, the CPU 60 outputs a command signal for instructing to stop the driving of the servo motor 30 to the servo motor 30 via the I / O 64. In response to this, the servo motor 30 stops rotating. Thereby, the rotation of the inspection object K is also stopped (step S4).

  Next, the CPU 60 acquires an image temporarily stored in the RAM 62 and performs image analysis processing (step S5). More specifically, the CPU 60 binarizes the image temporarily stored in the RAM 62 in units of one pixel. As a result, as shown in FIG. 6A, the density amount for each pixel is calculated. Then, the CPU 60 integrates the calculated density amount. For example, when all the numerical values shown in FIG. 6A are integrated, 1 + 2 + 2 + 3 + 3 + 4 + 5 + 6 + 6 + 9 = 41 is obtained. The density amount shown in FIG. 6A is darker as the numerical value is lower, and brighter as the numerical value is higher.

  Next, the CPU 60 determines whether or not the accumulated value exceeds a predetermined threshold value (step S6). If the threshold is not exceeded, it is determined that there is no ridge Ka (see FIG. 4B) on the surface of the inspection object K (step S6: NO), and the processing of the program ends.

  On the other hand, if the threshold value is exceeded (see FIG. 6B), it is determined that there is a ridge Ka (see FIG. 4B) on the surface of the inspection object K (step S6: YES), and the position is red. Image processing to change the color to yellow or yellow. That is, a process for displaying the image P1 as shown in FIG. 7 on the display unit 63 is performed (step S7), and the program process is finished. Thereby, it is possible to easily and easily specify the location where the eyelid Ka of the inspection object K exists. The numerical value on the left side (15.9 or 14.7) shown in the image P1 indicates the average contrast of the image indicating 疵 Ka, and the numerical value (48.0 or 51.0) in the middle in the figure is The maximum contrast (45.0 or 46.0) on the right in the figure indicates the maximum contrast of the image indicating 疵 Ka, and indicates the pixel of the image indicating 疵 Ka.

  Thus, according to the present embodiment described above, the inspection object K made of a rod shape is rotated by the rotation drive mechanism 3, and the axis of the inspection object K is added to the rotating inspection object K made of a rod shape. Since the light LI is irradiated from the LED illumination device 4 so that the brightness of the inspection object K is divided with the O2 direction as a boundary, when the 疵 Ka is formed on the inspection object K, the 疵 Ka is It is located in the dark field region K2 on the axis O2. Thereby, if the to-be-inspected object K which received the light LI irradiated from the LED illumination apparatus 4 with the line scan camera 5 is imaged, the 疵 Ka part will be imaged brightly. However, if the CPU 60 analyzes the image in which the 疵 Ka portion is brightly imaged and determines the presence or absence of 疵, the presence or absence of 疵 Ka can be accurately determined.

  Therefore, according to the present embodiment, it is possible to stably detect the presence or absence of wrinkles Ka on the surface of the inspection object K having a rod shape.

  Further, in the present embodiment, a method for uniformly binarizing the entire image that is generally performed is not used, but binarization is performed in units of one pixel, the density amount is calculated, and the calculated density The amount is integrated, and the integrated value is compared with a predetermined threshold value. Thereby, even if the imaging area is small, the presence or absence of the eyelid Ka of the inspection object K can be clearly determined, and a determination closer to visual observation can be made.

  In the present embodiment, when calculating the density amount per pixel, the lower the numerical value, the darker the image, and the higher the numerical value, the brighter the image. However, the present invention is not limited to this. You may do it. At this time, if the integrated value is below a predetermined threshold value, it may be determined that 疵 Ka (see FIG. 4B) exists on the surface of the inspection object K. good.

Second Embodiment
Next, a second embodiment of the surface flaw inspection apparatus relating to the surface flaw inspection method of the present invention will be described with reference to FIGS. In addition, about the same structure as 1st Embodiment, the same code | symbol is attached | subjected and description is abbreviate | omitted.

  The difference between the second embodiment and the first embodiment is that two LED lighting devices 4 are provided, and the other points are the same. The reason for providing two LED illumination devices 4 is that if the eyelid Ka of the inspection object K is very gentle and shallow, the light LI emitted from the LED illumination device 4 does not scatter or is scattered. There is a possibility of scattering to a position where the line scan camera 5 cannot capture an image. Then, the wrinkle cannot be picked up by the line scan camera 5, and thus there is a possibility that the surface flaw of the inspection object K cannot be detected. Therefore, in the present embodiment, two LED illumination devices 4 are provided so that such wrinkles can be detected.

  Specifically, as shown in FIG. 8, the LED illumination device 4 includes a first LED illumination device 4A and a second LED illumination device 4B, and the first LED illumination device 4A includes: The distance l1 in the horizontal direction from the center line O1 of the inspection object K, the height h1, the inclination angle θ1 (θ1 <90 °) with the center line O1 of the inspection object K as the base point, and the center line O1 of the inspection object K Until the irradiation distance L1 of the light LI (see FIG. 4A). The first LED lighting device 4A is provided with a white LED 4b1 made of a long bar as shown in FIG. 4A. The white LED 4b1 has one direction (in the illustration, a left diagonal direction). The directional film 4b2 is attached so that the light LI is irradiated only from the above.

  In addition, the second LED illumination device 4B has a horizontal distance l1 + l3 from the center line O1 of the object K to be inspected, a height h2, and an inclination angle θ3 (θ3 <90 with respect to the center line O1 of the object K to be inspected). °), the irradiation distance L2 of the light LIB (see FIG. 8B) up to the center line O1 of the inspection object K is arranged. And in this 2nd LED lighting apparatus 4B, white LED4Bb1 which consists of an elongate bar shown in FIG.8 (b) is provided, and white LED4Bb1 has one direction (in the illustration, right diagonal direction). The directional film 4Bb2 is attached so that the light LIB is irradiated only from the above. That is, light is emitted from the second LED lighting device 4B from a direction different from that of the first LED lighting device 4A.

  Thus, a method for detecting wrinkles of the inspection object K using the first LED illumination device 4A and the second LED illumination device 4B is stored in the ROM 61 of the image analysis control device 6 shown in FIG. The description will be made with reference to the processing contents of the program being executed.

  When the inspection object K composed of a bar shape including a steel bar conveyed from a conveyance line (not shown) is placed on the pair of rotating parts 31 (see FIG. 8), the CPU 60 instructs the servo motor 30 to be driven. Command signal to be output to the servo motor 30 via the I / O 64. In response to this, the servo motor 30 is driven to rotate. Thereby, as shown in FIG. 1, the inspection object K rotates in the direction of the arrow Y1 via the belt B (step S1). At this time, the light LI of the first LED illumination device 4A is irradiated, and the second LED illumination device 4B is turned off.

  Next, the CPU 60 acquires an image of the inspection object K rotated in the direction of the arrow Y1 captured by the line scan camera 5 via the I / O 64 (step S2). The acquired image is temporarily stored in the RAM 62.

  Next, the CPU 60 acquires an encoder capable of detecting the motor position output from the servo motor 30 via the I / O 64, and confirms whether the servo motor 30 has been rotationally driven a predetermined number of times (for example, twice) ( Step S3). If it has not been rotationally driven a predetermined number of times (step S3: NO), the process returns to step S2, and if it has been rotationally driven a predetermined number of times (step S3: YES), the process proceeds to step S4.

  Next, the CPU 60 outputs a command signal for instructing to stop the driving of the servo motor 30 to the servo motor 30 via the I / O 64. In response to this, the servo motor 30 stops rotating. Thereby, the rotation of the inspection object K is also stopped (step S4).

  Next, the CPU 60 outputs, to the LED illumination device 4 via the I / O 64, a command signal instructing that the first LED illumination device 4A is turned off and the light LIB of the second LED illumination device 4B is irradiated. . In response to this, the LED lighting device 4 turns off the first LED lighting device 4A and turns on the second LED lighting device 4B, that is, emits the light LIB (step S10).

  Next, the CPU 60 outputs a command signal for instructing to drive the servo motor 30 to the servo motor 30 via the I / O 64. In response to this, the servo motor 30 is driven to rotate. Thereby, as shown in FIG. 1, the inspection object K rotates in the direction of the arrow Y1 via the belt B (step S11).

  Next, the CPU 60 acquires the image of the inspection object K rotated in the direction of the arrow Y1 imaged by the line scan camera 5 via the I / O 64 (step S12). The acquired image is temporarily stored in the RAM 62.

  Next, the CPU 60 acquires an encoder capable of detecting the motor position output from the servo motor 30 via the I / O 64, and confirms whether the servo motor 30 has been rotationally driven a predetermined number of times (for example, twice) ( Step S13). If it has not been rotationally driven a predetermined number of times (step S13: NO), the process returns to step S12. If it has been rotationally driven a predetermined number of times (step S13: YES), the process proceeds to step S14.

  Next, the CPU 60 outputs a command signal for instructing to stop the driving of the servo motor 30 to the servo motor 30 via the I / O 64. In response to this, the servo motor 30 stops rotating. As a result, the rotation of the inspection object K is also stopped (step S14).

  Next, the CPU 60 acquires an image temporarily stored in the RAM 62 and performs image analysis processing (step S5). More specifically, the CPU 60 binarizes the image temporarily stored in the RAM 62 in units of one pixel. As a result, as shown in FIG. 6A, the density amount for each pixel is calculated. Then, the CPU 60 integrates the calculated density amount.

  Next, the CPU 60 determines whether or not the accumulated value exceeds a predetermined threshold value (step S6). If the threshold is not exceeded, it is determined that there is no ridge Ka (see FIG. 4B) on the surface of the inspection object K (step S6: NO), and the processing of the program ends.

  On the other hand, if the threshold value is exceeded (see FIG. 6B), it is determined that there is a ridge Ka (see FIG. 4B) on the surface of the inspection object K (step S6: YES), and the position is red. Image processing to change the color to yellow or yellow. That is, a process for displaying the image P1 as shown in FIG. 7 on the display unit 63 is performed (step S7), and the program process is finished. Thereby, it is possible to easily and easily specify the location where the eyelid Ka of the inspection object K exists.

  Thus, also in the present embodiment described above, the inspection object K made of a rod shape is rotated by the rotation drive mechanism 3, and the axis O2 of the inspection object K is added to the rotating inspection object K made of a rod shape. Since the light LI or the light LIB is irradiated from the LED illumination device 4 so that the brightness of the inspection object K is divided with the direction as a boundary, if the inspection object K is formed with 疵 Ka, the 疵 Ka is Anyway, it will be located in the dark field region K2 on the axis O2. Thereby, if the to-be-inspected object K which received light LI or light LIB irradiated from the LED illumination apparatus 4 with the line scan camera 5 is imaged, the 疵 Ka part will be imaged brightly. However, if the CPU 60 analyzes the image in which the 疵 Ka portion is brightly imaged and determines the presence or absence of 疵, the presence or absence of 疵 Ka can be accurately determined.

  Therefore, also in this embodiment, it is possible to stably detect the presence or absence of wrinkles Ka on the surface of the inspection object K made of a rod shape.

  In the present embodiment, even if the eyelid Ka of the inspection object K is very gentle and shallow, two LED illumination devices 4 are provided to irradiate light from different directions. The 疵 Ka portion shines brightly with the light LI, LIB, and the 疵 Ka portion shining brightly can be imaged by the line scan camera 5. Thereby, even if the eyelid Ka of the inspected object K is a very gentle and shallow eyelid, the presence or absence of the eyelid Ka can be accurately determined.

  By the way, the LED illumination device 4 can be as shown in FIG. The LED illumination device 4C includes an LED illumination bar 40 in which LEDs are evenly arranged, and an acrylic round bar 41 that collects and amplifies diffused light from the LED illumination bar 40 to irradiate a strip-shaped light LIC. Has been. With this configuration, the LED illuminating device 4C can irradiate the strip-shaped light LIC having the gradation of light and shade shown by the broken line GD, and the irradiated light LIC is irradiated to the inspection object K. . At this time, although not shown, a bright field region K1 that is a bright region of the inspection object K and a dark region with the axis O2 of the inspection object K as a boundary as shown in FIG. A dark field region K2 is formed.

  Thus, when the inspection object K is irradiated with the strip-shaped light LIC having such a gradation, if the inspection object K has 疵 Ka, local distortion occurs and the 疵 Ka portion is generated. Can be captured more clearly by the line scan camera 5. In other words, if 疵 Ka occurs in the inspection object K, the specular reflection angle of the light LIC changes, so if the line scan camera 5 captures the change, it will be locally applied to the strip-shaped light LIC composed of light and shade gradations. Distortion will occur. Therefore, the で き る Ka portion can be captured with the line scan camera 5 more clearly.

  On the other hand, in the first embodiment and the second embodiment, as shown in FIGS. 3 and 8, an example in which the inspection object K is disposed at a substantially intermediate position between the LED illumination device 4 and the line scan camera 5. However, the present invention is not limited thereto, and the inspection object K may be disposed on the LED illumination device 4 side, or the inspection object K may be disposed on the line scan camera 5 side. That is, as shown in FIG. 4B, a bright field region K1 that is a bright region and a dark field region K2 that is a dark region can be formed on the inspection object K with the axis O2 of the inspection object K as a boundary. Any arrangement is possible.

  In the first embodiment, FIG. 4A shows an example in which the light LI is irradiated only from one direction (left oblique direction in the drawing), but not only the left oblique direction but also the right oblique direction, It may be vertical.

  In the first embodiment and the second embodiment, the servo motor 30 is exemplified as the driving means for rotating the inspection object K. However, the present invention is not limited to this, and any device can be used as long as the inspection object K can be rotated. But it ’s okay.

1 Surface wrinkle inspection device 3 Rotation drive mechanism (rotating means)
4 LED lighting device (light irradiation means)
5 Line scan camera (imaging means)
6 Image analysis control device 60 CPU (image analysis means, determination means)
K Inspected object Ka ２ O2 Axis LI, LIB, LIC Light LIa Scattered light

Claims (4)

A step of rotating the inspection object made of a rod shape a predetermined number of times at a predetermined position by a rotating means;
An illumination bar in which a plurality of light emitting elements are evenly arranged and a diffused light diffused from the illumination bar are collected so that the brightness of the object to be inspected is separated from the axis direction of the rotating object to be inspected. And the step of irradiating the object with the band-shaped light by the light irradiation means constituted by an acrylic round bar that irradiates the band-shaped light in which bright and dark light appears alternately ,
Imaging an inspection object that has received the band-shaped light irradiated by the light irradiation means with an imaging means;
Integrating a density amount in units of one pixel based on an image captured by the imaging unit by an image analysis unit;
A surface wrinkle inspection method including a step of determining the presence or absence of wrinkles on the surface of the object to be inspected based on whether or not the concentration amount accumulated by the image analysis means exceeds a predetermined threshold value.   The surface flaw inspection method according to claim 1, wherein the band-shaped light irradiated by the light irradiation means is irradiated only from one direction. The light irradiation means includes a first light irradiation means and a second light irradiation means,
The band-shaped light irradiated by the first light irradiation means is irradiated only from one direction,
The surface flaw inspection method according to claim 1, wherein the band-shaped light irradiated by the second light irradiation unit is irradiated only from another direction different from the one direction.   The surface defect inspection method according to claim 1, wherein the imaging unit is a line scan camera.

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