JPS63201556A - Method for discriminating gouge of gear - Google Patents

Abstract

PURPOSE:To exactly discriminate the gouge on the tooth face of a gear to be inspected by forming plural differential images between the image on the tooth face of said gear and the image on the other tooth face thereof and comparing the luminance of the added image of the differential images and prescribed reference luminance value. CONSTITUTION:The tooth faces are first photographed by a camera 4 at every prescribed rotating position of the gear 1 and the plural stack images A, B, C are taken in. The desired image D to be discriminated is then taken in and is compared with the respective stack images A, B, C and thee differential images A', B', C' indicating the difference in the luminance are formed. One added image S is formed by adding these images A', B', C'. The luminance of the added image S and the previously formed reference luminance are compared and are binarized. Only the luminance change 9 by the gouge appearing in the image D is thereby made to remain and, therefore, the presence or absence of the gouge is exactly discriminated.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a dent discrimination method for detecting dents and other flaws occurring on the tooth surface of a gear.

(Prior art and problem to be solved) If a gear with scratches on the tooth surface is used, problems such as increased vibration or noise of the gear device during operation will occur. Conventionally, these products are removed as defective products.

For this purpose, a method is known in which a gear to be determined is installed in a predetermined gear device, its vibrations are detected, and dents on the gear are determined based on the magnitude of the vibrations. but,
With this method, the process is complicated and it is not possible to speed up the processing of the discrimination operation, and since factors other than dents also affect the magnitude of vibration, it is difficult to accurately detect dents, etc. There's a problem.

A method is also known in which a tooth surface of a gear is photographed and dents and the like are determined from the image. However, with this conventional image-based discrimination method, the light from the illumination that illuminates the tooth surface during photographing is diffusely reflected, and small dents may not be detected.

(Means for Solving the Problem) The present invention was constructed in view of the above circumstances, and is a method for accurately determining gear dents, etc. using images of gear tooth surfaces. The purpose of this invention is to provide a method for identifying marks, etc.

The dent determination method of the present invention is a method of photographing a gear tooth surface and evaluating the brightness of the obtained image to determine the presence or absence of scratches such as dents on the gear tooth surface. Image of the gear tooth surface to be inspected is created by photographing the gear tooth surface to be inspected and the gear tooth surface different from that tooth surface at intervals of A difference image is created by comparing images of the tooth surface and a different gear tooth surface, and a difference image representing the difference in brightness between the images is created.The difference images are added together to create an addition image, and the brightness of this addition image and It is characterized in that the presence or absence of a dent is determined by comparing with a predetermined brightness reference value.

(Function) According to the present invention, the gear on which scratches such as dents are to be determined is brought in front of a device for creating a tooth surface image, such as a camera, and the tooth surface is photographed. In this case, different images of the tooth surface are created at predetermined intervals for one gear to be determined using one or more cameras, that is, a photographing means. Therefore, multiple images will be created for one gear. Further, in these images, even if the tooth surfaces are different, the direction in which the tooth surfaces are photographed does not substantially differ between the images. That is, the images are created so that when superimposed, the photographed teeth exactly match. In order to create such an image, the gear is preferably rotatably arranged in front of the camera, and the tooth surface is photographed at every predetermined rotation angle.

Next, the plurality of images created by the above method are compared with each other, and a difference image representing the difference in brightness is created. Then, in order to emphasize the difference in brightness, a predetermined number of difference images are added together to create an added image. The brightness of this added image is compared with a predetermined brightness reference value to digitize the brightness, and if the brightness is greater than the reference value, it is determined that there is a dent.

In this case, preferably, the image to be evaluated is compared with a plurality of images showing other tooth surfaces created before the image to create a difference image. Then, one added image is created by adding these respective difference images together. Therefore, according to this method, when brightness representing a dent appears on the image to be evaluated, this brightness is emphasized in the added image according to the number of difference images.

The brightness reference value can be set, for example, to correspond to a flaw of a certain size or more that has a significant effect on the noise of the gear device.

(Effects of the Invention) According to the present invention, images created to represent different tooth surfaces at predetermined intervals are compared with each other to create a difference image, thereby performing relative evaluation between the images. There is. This makes it possible to eliminate the influence of diffused reflection caused by illumination, and to accurately determine the presence or absence of dents and the like.

Further, since the brightness corresponding to the dents and the like generated in the difference image is emphasized in the added image, it is possible to improve the reliability of detecting the dents and the like.

(Description of Embodiment) Hereinafter, one embodiment of the present invention will be described with reference to the drawings.

Referring to FIG. 1, there is schematically shown an apparatus to which a dent discrimination method according to an embodiment of the present invention can be applied.

On the right side of FIG. 1, a gear 1 for identifying dents, etc. is supported on a base 3 disposed on a reference surface 2 so as to be rotatable around a vertical axis. A camera 4 is arranged in front of the gear 1 so as to face the tooth surface. Lights 5 and 6 are arranged above and below the camera 4 to illuminate the tooth surfaces of the gears.

Referring to FIG. 2, the tooth surface of gear 1 is photographed by camera 4 at a predetermined rotational position, and in this example, the tooth surface is photographed every time gear 1 is rotated by 30 degrees. It has become. Therefore, 12 for one gear
This results in two images being obtained. Moreover, the shape of the tooth 7 appearing in each image obtained by this method is a pear.

Next, the contents of the image processing of this example will be explained with reference to FIGS. 3 to 6.

The method of this example is performed in the flow shown in FIG.

In this method, first, as preprocessing, a plurality of stacked images ASB and C (see FIG. 6) taken every 30° rotation of the gear 1 are captured in the flow shown in FIG.

Next, the target image to be determined is imported. And the fifth
In the flow shown in the figure, image processing is performed to compare the target image and each stack image ASBSC to create difference images A', B', and C' representing differences in brightness. In this case, the sixth
As shown in the figure, when brightness changes 8 and 9 representing scratches such as dents appear in image B and image respectively, brightness change 9 in image B appears in all of the difference images A', B', and C', The brightness change 8 of image B appears only in difference image B'. next,
One added image S is created by adding these difference images A', B', and C'. Both brightness changes 8 and 9 appear in this image. However, the brightness of this brightness change 9 is emphasized compared to that of brightness change 8. Next, the brightness of this added image S is compared with a reference brightness created in advance and binarized. As a result, only the emphasized luminance change 9 remains in the added image S. Therefore, in this case, gear 1 is determined to be defective. Next, gear 1 is rotated an additional 30 degrees and a similar operation is performed. As a result, a summation image S for each image is created and comparison with the reference brightness is performed one after another, thereby determining the presence or absence of scratches. Then, only the gear l that is not determined to be defective until the last image is processed as a good item.

According to the above method, since each image is compared, it is not affected by brightness changes other than scratches such as dents appearing in the images, and therefore it is possible to accurately discriminate dents and the like. Note that the method of the present invention can be effectively applied not only to determining the above-mentioned gear dents, etc., but also to detecting paint defects.

[Brief explanation of the drawing]

FIG. 1 is a schematic elevational view showing an example of a device to which the dent discrimination method of the present invention can be applied, FIG. 2 is a schematic plan view of the device shown in FIG. 1, and FIGS. 3 to 5 are FIG. 6, a flowchart showing the procedure for implementing the method of the present invention, is an explanatory diagram of the image processing step in implementing the present invention. 1...Gear, 2...Reference plane, 3...
...Base, 4...Camera, 5.6...
・Light, 7...Teeth, 8.9...Brightness change.

Claims (1)

[Claims] This is a method of photographing a gear tooth surface and evaluating the brightness of the obtained image to determine the presence or absence of scratches such as dents on the gear tooth surface. A tooth surface and a different gear tooth surface are photographed to create multiple images of the different tooth surfaces from substantially the same direction, and the image of the gear tooth surface to be inspected and the image of the gear tooth surface different from that tooth surface are mutually combined. A difference image is created that represents the difference in brightness between the images by comparison, a summation image is created by adding these difference images, and a dent is detected by comparing the brightness of this summation image with a predetermined brightness reference value. A method for determining dents on a gear, the method comprising determining the presence or absence of a dent on a gear.