JP7501093B2 - Flaw detection device and flaw detection method - Google Patents

Description

The present invention relates to a flaw detection device and flaw detection method that generate an image of the outer surface of an object having a protrusion provided on the outer surface of a rod-shaped or cylindrical member.

Patent document 1 describes a technology that uses a line camera to capture images of the tips of gear teeth, combines the images to generate an expanded image of the tooth tip surface, and inspects the gear surface.

JP 2018-36172 A

However, when the protrusions on the surface of an object are large, such as in the case of gears with long teeth, a single line camera cannot capture defective areas because the base of the protrusion is in the shadow of adjacent protrusions. As a result, the image obtained does not reflect the entire surface of the object, and it is not possible to correctly check the surface condition of the entire outer circumference, including the protrusions.

The present invention has been made in consideration of the above problems, and aims to provide a flaw detection device and flaw detection method that generate an image of the outer peripheral surface of a cylindrical shape in which defective parts are suppressed.

In order to achieve the above object, a flaw detection device according to the present invention is a flaw detection device that generates an image of the outer peripheral surface of an object having a protrusion that protrudes outward from a cylindrical outer peripheral surface, and includes an imaging element having a plurality of imaging pixels arranged in a matrix, an imaging device having an optical system that forms an image on the imaging element, a rotation device that rotates the imaging device and the object relatively in the circumferential direction of the object, an imaging unit that causes the imaging device to capture images of the outer peripheral surface of the object at a predetermined time interval synchronized with the relative rotation by the rotation device, an area identification unit that identifies and acquires, from the image data captured by the imaging device, first area data in which a predetermined first surface side of the protrusion is imaged and second area data in which a second surface side opposite to the first surface side of the protrusion is imaged, and an image synthesis unit that synthesizes the first area data and the second area data to generate an expanded image of the outer peripheral surface.

In order to achieve the above object, another flaw detection method of the present invention is a flaw detection method for generating an image of the outer peripheral surface of an object having a protrusion that protrudes outward from a cylindrical outer peripheral surface, in which a rotating device rotates an imaging device having an imaging element with a plurality of imaging pixels arranged in a matrix and an optical system that forms an image on the imaging element and the object relative to the circumferential direction of the object, and an imaging unit causes the imaging device to capture images of the outer peripheral surface of the object at a predetermined time interval synchronized with the relative rotation by the rotating device, and an area identification unit identifies and acquires first area data in which a predetermined first surface side of the protrusion is imaged and second area data in which a second surface side opposite to the first surface side of the protrusion is imaged from the image data captured by the imaging device, and an image synthesis unit generates an expanded image of the outer peripheral surface by synthesizing the first area data and the second area data, and detects scratches on the surface of the object based on the expanded image.

This flaw detection device and flaw detection method make it possible to obtain an image of the outer peripheral surface of the object in which the occurrence of defects caused by protrusions on the outer peripheral surface of the object is suppressed.

FIG. 2 is a perspective view showing the mechanical configuration of the flaw detection device. FIG. 2 is a side view showing the mechanical configuration of the flaw detection device. 2 is a block diagram showing a functional configuration of an image generating device provided in the flaw detection device. FIG. 13 is a diagram showing the relationship of area data acquired by an area specifying unit; FIG. 13 is a diagram showing a composite image which is an expanded image. FIG. 13 is a diagram showing the correspondence between an object and area data.

Below, the embodiments of the flaw detection device and flaw detection method according to the present invention will be described with reference to the drawings. Note that the numerical values, shapes, materials, components, positional relationships of the components, connection states, steps, and order of steps shown in the following embodiments are merely examples and are not intended to limit the present invention. In addition, although multiple inventions may be described as one embodiment below, components not described in the claims are described as optional components with respect to the invention related to that claim. In addition, the drawings are schematic diagrams in which emphasis, omissions, and ratios have been appropriately adjusted to explain the present invention, and may differ from the actual shapes, positional relationships, and ratios.

Figure 1 is a perspective view showing the mechanical configuration of the flaw detection device. Figure 2 is a side view showing the mechanical configuration of the flaw detection device. As shown in these figures, the flaw detection device 100 generates an image of the outer peripheral surface of an object 200 having a protrusion 210 protruding outward from its cylindrical outer peripheral surface for flaw detection, and includes an imaging device 110, a rotation device 120, and an image generation device 130. In this embodiment, the flaw detection device 100 includes an illumination device 140.

The object 200 is an object to be inspected for the presence or absence of scratches based on the developed image of the outer circumferential surface obtained by the flaw detector 100, and has a protrusion 210 that protrudes outward from the cylindrical outer circumferential surface. The type of object 200 is not particularly limited, and examples include gears including spur gears and worm shafts, fasteners including bolts and wood screws, cutting tools including hobs and end mills, etc. In the case of this embodiment, a pinion shaft is exemplified as the object 200, and the protrusion 210 is a ridge that corresponds to the teeth of the pinion shaft.

The imaging device 110 is a so-called area camera that captures an image of the outer circumferential surface of the object 200 together with the protrusion 210, and includes an imaging element 111 (see FIG. 4) and an optical system 112 (see FIG. 4). The imaging element 111 is a device that acquires two-dimensional image data of an image formed by the optical system 112, and has a plurality of imaging pixels arranged in a matrix. The type of the imaging element 111 is not particularly limited, and examples include a CCD (Charge Coupled Devices) type imaging element 111 and a CMOS (Complementary Metal Oxide Semiconductor) type imaging element 111. The optical system 112 is formed by a single or multiple optical elements that form an image on the imaging element 111. The type of the optical system 112 is not particularly limited. In this embodiment, the optical system 112 has a depth of field that is approximately the protrusion amount (tooth height) of the protrusion 210, and is in focus from the top part (tooth tip) of the protrusion 210 to the bottom part (tooth base) of the protrusion 210. The optical system 112 is arranged so that the rotation axis 222 of the object 200 held by the rotation device 120 and the optical axis 221 are perpendicular to each other.

The rotation device 120 is a device that rotates the imaging device 110 and the object 200 relative to each other in the circumferential direction of the object 200. In this embodiment, the imaging device 110 is fixedly disposed relative to the rotation device 120, and the rotation device 120 realizes the relative rotation between the imaging device 110 and the object 200 by rotating the object 200 around the rotation axis 222 of the object 200. The specific form of the rotation device 120 is not particularly limited, but in this embodiment, the rotation device 120 arranges a pair of rollers consisting of two rollers 121 that abut the circumferential surface of the shaft portion 211 of the object 200 at both ends of the object 200, and holds the object 200 so that the optical axis 221 of the imaging device 110 and the rotation axis 222 of the object 200 are perpendicular to each other. Each roller 121 is arranged so that the rotation axis of the roller 121 is parallel to the rotation axis 222 of the object 200. At least one of the rollers 121 of the rotation device 120 is given a rotational driving force by a drive device (not shown), and the other rollers 121 rotate freely.

The lighting device 140 is a device that irradiates light onto the outer peripheral surface of the object 200 so that the imaging device 110 can image the outer peripheral surface of the object 200. The type of lighting device 140 is not particularly limited, but in this embodiment, the lighting device 140 includes a first light source 141, a second light source 142, and a holding mechanism 143.

The first light source 141 irradiates light onto the first surface side 231 of the protrusion 210. The second light source 142 irradiates light onto the second surface side 232, which is the opposite side to the first surface side 231. In the present embodiment, the rotation axis 222 of the object 200 is disposed along the Y axis in the figure, and the surface (tooth surface) of the protrusion 210 whose normal line faces in a clockwise (right-handed) direction from the negative side (Y-) of the Y axis to the positive side (Y+) of the Y axis is the first surface side 231, and the surface (tooth surface) of the protrusion 210 whose normal line faces in a counterclockwise (left-handed) direction is the second surface side 232.

The type of light emitted by the first light source 141 and the second light source 142 is not particularly limited, and may be monochromatic light such as laser light or LED light, or may be white light. In addition, light other than visible light may be used as long as the imaging device 110 can capture an image. For example, in a case where a fluorescent powder is attached to the outer peripheral surface of the object 200, light that is not visible light and includes a wavelength that excites the fluorescent material may be irradiated. The first light source 141 and the second light source 142 irradiate the entire area of the object 200 imaged by the imaging device 110, that is, the top of the protrusion 210 (tooth tip surface), the first surface side 231, the second surface side 232, and the space between adjacent protrusions 210 (tooth base) in the area with as uniform illuminance as possible.

The holding mechanism 143 is a member that holds the first light source 141 and the second light source 142 so that the positions of the first light source 141 and the second light source 142 can be moved along the outer circumferential surface of the object 200. In the present embodiment, the holding mechanism 143 has an arc shape centered on the rotation axis 222 of the object 200 held by the rotating device 120, and can move the first light source 141 and the second light source 142 along the circumference centered on the rotation axis 222 and hold them at a predetermined position. In addition, the holding mechanism 143 holds the first light source 141 and the second light source 142 so that they can be rotated around an axis parallel to the rotation axis 222.

Figure 3 is a block diagram showing the functional configuration of an image generating device provided in the flaw detection device. As shown in the figure, the image generating device 130 is one of the ECUs (Electronic Control Units) that controls the imaging device 110 and the rotation device 120 to generate a developed image of the outer circumferential surface of the target object 200. In the case of this embodiment, the image generating device 130 includes an imaging unit 131, a region identification unit 132, an image synthesis unit 133, a rotation control unit 134, and a flaw detection unit 135 as processing units realized by executing a program recorded in a non-transitory storage medium.

The rotation control unit 134 controls the relative rotation between the imaging device 110 and the object 200 by the rotation device 120. In this embodiment, the rotation control unit 134 controls a drive device provided in the rotation device 120 to rotate the object 200 at a constant speed. The rotation control unit 134 may derive an appropriate rotation speed by inputting the specifications of the object 200. In addition, after rotating the object 200 at a predetermined rotation speed, the object 200 may be rotated at a specified location at a rotation speed slower than the previous rotation speed.

The imaging unit 131 is a processing unit that causes the imaging device 110 to capture images of the outer circumferential surface of the object 200 at a predetermined time interval synchronized with the relative rotation of the object 200 and the imaging device 110 by the rotation device 120. The imaging unit 131 may cause the imaging device 110 to capture images at a fixed time interval, for example, 30 fps. In addition, the imaging device 110 may capture images of the object 200 based on a synchronization signal obtained from the rotation control unit 134, or at a time interval corresponding to the rotation speed of the object 200.

4 is a diagram showing the relationship of the area data acquired by the area identification unit. As shown in the figure, the area identification unit 132 identifies and acquires the first area data 151 in which the first surface side 231 of the protrusion 210 is imaged, and the second area data 152 in which the second surface side 232 of the protrusion 210 is imaged, from the image data 150 captured by the image sensor 111 of the imaging device 110. In the case of this embodiment, the area identification unit 132 also identifies and acquires the third area data 153 in which the top part of the protrusion 210 is imaged from the image data 150. The way in which the area identification unit 132 identifies the area is not particularly limited, and the first area data 151, the second area data 152, and the third area data 153 may be identified by an operator visually checking the image made of the image data 150 and specifying multiple areas. In addition, the first area data 151, the second area data 152, and the third area data 153 may be identified appropriately by inputting the specifications of the object 200.

The region identification unit 132 may obtain the first region data 151, the second region data 152, and the third region data 153 by giving instructions to the imaging device 110. In addition, after obtaining the image data 150, the region identification unit 132 may cut out the first region data 151, the second region data 152, and the third region data 153 from the obtained image data 150.

The widths of the first region data 151, the second region data 152, and the third region data 153 may be data obtained from one imaging pixel, or may be data obtained from multiple imaging pixels.

The image synthesis unit 133 synthesizes the first area data 151, the second area data 152, and the third area data 153 to generate a first composite image 161, a second composite image 162, and a third composite image 163, as shown in FIG. 5, which are expanded images obtained by capturing images of the outer circumferential surface of the object 200 in different directions. The image synthesis unit 133 displays the generated first composite image 161, the second composite image 162, and the third composite image 163 on the display device 170. The image synthesis unit 133 may display the first composite image 161, the second composite image 162, and the third composite image 163 side by side so that portions of the images captured at one time by the imaging element 111 are lined up.

The scratch detection unit 135 detects scratches using artificial intelligence such as deep learning based on the first composite image 161, the second composite image 162, and the third composite image 163 generated by the image synthesis unit 133. The scratch detection unit 135 can mark corresponding locations in the first composite image 161, the second composite image 162, and the third composite image 163 so that the detected scratches can be visually recognized by the worker.

According to the flaw detection device 100 equipped with the image generating device 130 described in this embodiment, the outer peripheral surface of the object 200 can be imaged from multiple angles using a single imaging device 110, so that an expanded image can be generated in which defects caused by the protrusion 210 are suppressed. Therefore, it is possible to detect flaws occurring on the outer peripheral surface of the object 200 without missing them.

In addition, since multiple angles are acquired at once by one image sensor 111, it is possible to generate an unfolded image with few missing parts at high speed. For example, when the target object 200 is a pinion shaft in which the thickness (tooth thickness) of the base (tooth base) side of the protrusion 210 is thinner than the thickness of the tip (tooth tip) side, a defective part that cannot be imaged by a single line camera may occur at the base (tooth base) part of the protrusion 210. However, with the above-mentioned flaw detection device 100, multiple line cameras are not required, and the first surface side 231 including the tip of the protrusion 210 and the second surface side 232 can be imaged by a single image sensor 110, and flaw detection can be performed based on the obtained images.

The present invention is not limited to the above-described embodiment. For example, the components described in this specification may be combined in any way, or some of the components may be removed to create another embodiment of the present invention. The present invention also includes modifications that are made to the above-described embodiment by those skilled in the art without departing from the spirit of the present invention, i.e., the meaning of the words in the claims.

For example, in the embodiment, the case where first region data 151, second region data 152, and third region data 153 are acquired is described, but as shown in FIG. 6, fourth region data 154 and fifth region data 155 may also be acquired to generate a fourth composite image and a fifth composite image.

In addition, in FIG. 4, a case is described in which the focal point of the optical system 112 is outside the object 200, but the focal point may be inside the object 200.

The flaw detection device and flaw detection method can be used to detect flaws in gears, screws, cutting tools, and other items that have protrusions on their outer surfaces.

100... flaw detection device, 110... imaging device, 111... imaging element, 112... optical system, 120... rotation device, 121... roller, 130... image generation device, 131... imaging unit, 132... area identification unit, 133... image synthesis unit, 134... rotation control unit, 135... flaw detection unit, 140... lighting device, 141... first light source, 142... second light source, 143... holding mechanism, 150... image data, 151... first area data, 152... second area data, 153... third area data, 154... fourth area data, 155... fifth area data, 161... first composite image, 162... second composite image, 163... third composite image, 170... display device, 200... object, 210... protrusion, 211... shaft, 221... optical axis, 222... rotation axis, 231... first surface side, 232... second surface side

Claims (5)

A flaw detection device that generates an image of an outer peripheral surface of an object having a cylindrical outer peripheral surface having a plurality of protrusions protruding outward in a circumferential direction,
an imaging device including an imaging element having a plurality of imaging pixels arranged in a matrix and an optical system that forms an image on the imaging element;
a rotation device that rotates the imaging device and the object relatively in a circumferential direction of the object;
an imaging unit that causes the imaging device to capture images of an outer circumferential surface of the object at predetermined time intervals synchronized with the relative rotation by the rotation device;
a region specifying unit that specifies and acquires, from image data captured by the imaging device, first region data in which a predetermined first surface side of the protrusion is imaged and second region data in which a second surface side opposite to the first surface side of the protrusion is imaged;
an image synthesis unit that synthesizes a plurality of the first region data to generate a first synthetic image that is a synthetic image of the first surface side of the protrusion, and synthesizes a plurality of the second region data to generate a second synthetic image that is a synthetic image of the second surface side of the protrusion ;
A flaw detection device comprising: The flaw detection device according to claim 1 , further comprising a rotation control unit that controls relative rotation between the imaging device and the target object by the rotation device. The flaw detection device according to claim 1 or 2, comprising an illumination device including a first light source that irradiates light onto the first surface side of the protrusion, a second light source that irradiates light onto the second surface side, and a holding mechanism that holds the first light source and the second light source so that the positions of the first light source and the second light source can be moved along the outer circumferential surface. The flaw detection device according to claim 1 , further comprising a flaw detection unit that detects flaws on a surface of an object using artificial intelligence based on the unfolded image acquired from the image synthesis unit. A flaw detection method for generating an image of an outer peripheral surface of an object having a cylindrical outer peripheral surface having a plurality of protrusions protruding outward in a circumferential direction, the method comprising:
an imaging device including an imaging element having a plurality of imaging pixels arranged in a matrix and an optical system for forming an image on the imaging element, and a rotation device relatively rotates the object and the imaging device in a circumferential direction of the object;
an imaging unit causes the imaging device to capture images of an outer circumferential surface of the object at predetermined time intervals synchronized with the relative rotation by the rotation device;
a region identifying unit identifying and acquiring first region data in which a predetermined first surface side of the protrusion is imaged and second region data in which a second surface side opposite to the first surface side of the protrusion is imaged from the image data captured by the imaging device;
an image synthesis unit synthesizes a first composite image, which is a composite image of the first surface side of the protrusion, by synthesizing a plurality of the first region data, and a second composite image, which is a composite image of the second surface side of the protrusion, by synthesizing a plurality of the second region data,
A flaw detection method for detecting flaws on an object surface based on the unfolded image.

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