JP6360782B2 - Inspection method of screws - Google Patents

Description

  The present invention relates to a screw inspection method using a conveying device that conveys screws in a hanging shape and an image processing inspection device.

  In assembly work of automobiles and consumer products, the tightening work of screws has been automated, and it has become difficult for workers at the assembly site to find and confirm defective products. For this reason, screw manufacturers are strongly required to prevent various defective products from being mixed, such as foreign products, unprocessed products, and poorly assembled products.

  Currently used screws are classified into many types according to the shape of each part such as the head and the screw part. For example, classification based on the shape of the head, classification based on the shape of the screw portion, or classification based on the presence or absence of a washer. In the present invention, the screws are a general term for screws incorporating a plain washer or a spring washer. Thus, it is extremely difficult to accurately visually inspect many products for each classification. Therefore, conventionally, a method of inspecting a defective product by image processing has been performed (see Patent Document 1 and Patent Document 2).

  In the inspection method described in Patent Document 1, the screw with the head is positioned and held in a state of facing the CCD camera, illumination light is irradiated between the CCD camera and the head of the screw with the head, and the top of the screw When there is a defective convex part in the operation hole provided in the above, a shadow is produced by the convex part, and in this state, the top of the screw is copied by the CCD camera, and the obtained image is processed by the discriminating device. It is a method for inspecting a screw with a head that determines whether or not the bottom of the operation hole has a defect based on image information.

  On the other hand, Patent Document 2 binarizes an image of a female thread portion of a screw molded part because it is imaged by an imaging means, and analyzes only a portion where an arc-shaped striped pattern appears clearly from the binarized image. A method for inspecting the quality of a female thread molded part is described in which the number of white pixels or the number of black images in the area is extracted and analyzed to determine whether the female thread molded part is good.

Japanese Patent No. 4437672 Japanese Patent No. 4758823

  In any of these conventional inspection methods, a part of the screw can be inspected, but the entire screw cannot be inspected.

  That is, in the method for inspecting a screw with a head disclosed in Patent Document 1, since the operation hole provided in the top of the screw is inspected for quality, the screw that can be inspected by this inspection method has a head. It is limited to screws. Therefore, it is impossible to inspect the entire part from the head to the screw part.

  On the other hand, since the inspection method described in Patent Document 2 is configured to determine the quality of female thread forming, the inspection site is limited to the female thread portion. As a result, the entire female screw cannot be inspected.

  Moreover, these conventional inspection methods using image processing require specialized knowledge and many settings necessary for image processing, and it is difficult for general workers to determine each part using image processing. It was.

  For example, when determining the diameter of a screw head by image processing, an operator first finds a part corresponding to the head on an inspection screen that displays an image, and then an edge necessary for measuring the diameter. Identify the location. Furthermore, a setting operation for obtaining the diameter from the difference in coordinates of the specified edge position is required.

  Such setting work is performed while viewing the product image on the inspection screen based on the knowledge and experience of the worker. As a result, there are many situations in which inspection contents vary due to differences in the knowledge and experience of the workers, and the inspection apparatus is not fully utilized.

  Therefore, the present invention was created to solve the above-described problems, and can be easily determined even by an operator who has no specialized knowledge or experience in image processing, and can also perform high-speed processing in a short time. The purpose is to provide an inspection method for screws.

  In order to achieve the above-mentioned object, the first means in the present invention includes a conveying path 10 that conveys the screw S while holding the head S1 in a hanging manner with the conveying tool 11 sandwiching the shaft portion S2, and a predetermined position. Screws using a side camera 20 that images the entire screw S from the side surface direction of the carrier 11, an upper camera 40 that images the upper surface of the head S1 of the screw S, and an image processing inspection apparatus 50 that processes the images of each camera. In a similar inspection method, an image of the entire screw S imaged by the side camera 20 is binarized, and an upper head shape and a lower shaft shape with the carrier 11 as a boundary from the binarized image. The type of the screw S is determined from the combination and the top surface shape of the head S1 imaged by the upper camera 40, and a binarized image is displayed on the inspection screen 51 of the image processing inspection apparatus 50, and the determined type of the screw S Pre-set according to Displays rectangular measuring frame T enclosing a measurement position of each part, each data measured automatically for each said measurement frame T and product data, in the inspection method for determining the quality of the screw on the basis of the product data.

  In the inspection method, the second means automatically measures the diameter and height of the head S1 in the measurement frame T that surrounds the entire binarized shape of the head S1, and sets the product data. Is.

  In the inspection method, the third means automatically measures the length of the shaft portion S2 in the measurement frame T that encloses the entire shape of the shaft portion S2 that has been binarized to obtain the product data.

  According to a fourth means, in the inspection method, the length and diameter of the screw portion S3 are automatically measured by the measurement frame T that surrounds the screw portion S3 from the binarized shape of the shaft portion S2, and the product data and To do.

  In the inspection method, in the inspection method, the left and right screw threads S4 are respectively surrounded by the measurement frames T from the binarized shape of the shaft portion S2, and the density of the binarized image is measured in each measurement frame T. Edge processing by projection is performed, and the pitch of the thread S4 is automatically measured from the contour position of the valley of each thread S4 to obtain the product data.

  As described in claim 1 of the present invention, the entire image of the side surface of the screw S imaged by the side camera 20 is binarized, and the upper head shape and the lower portion from the binarized image with the carrier 11 as a boundary. By determining the type of the screw S from the combination with the shaft shape and the shape of the upper surface of the head S1 imaged by the upper camera 40, the inspection according to the type of the screw S can be performed rationally.

  In addition, a binarized image is displayed on the inspection screen 51 of the image processing inspection apparatus 50, and a rectangular measurement frame T that surrounds the measurement position of each part according to the determined type of the screw S is displayed. Since each data automatically measured for each measurement frame T is used as product data, the data of items to be inspected for the screw S can be automatically set. As a result, there is no need for the setting work that is performed while viewing the product image on the inspection screen based on the knowledge and experience of the worker as in the past, and the worker who has no specialized knowledge and experience regarding image processing. However, it has become possible to inspect with extremely simple operations.

  Furthermore, since the inspection is carried out on the conveyance path 10 that conveys the shaft S <b> 2 of the screw S while supporting the head S <b> 1 of the screw S in a hanging manner, the conveyance tool 11 can be inspected in a short time. Thus, a large amount of screws S can be processed at high speed.

  In the inspection method according to claims 2 to 5, since the measurement of each part of the screw S is automatically performed by the measurement frame T, various setting operations performed by the conventional image processing inspection apparatus are completely unnecessary. . As a result, since the operator's knowledge and experience are not required when using the image processing inspection apparatus 50, conventional inconveniences such as variations in inspection contents and insufficient utilization of the inspection apparatus are eliminated. . Further, based on such product data, it is possible to easily determine a fatal defect such as a different product type, a different product number, or an unprocessed threaded portion.

  As described above, according to the present invention, an initial object that an operator who has no specialized knowledge or experience in image processing can easily make a determination and can perform high-speed processing in a short time has been achieved.

It is the schematic which shows one Example of the test | inspection apparatus used by this invention. It is the schematic which shows the imaging state of this invention. It is a figure which shows the test | inspection screen of this invention. It is a figure which shows the data screen of this invention. It is a figure which shows the other example of the data screen of this invention. It is a figure which shows the binarized image of this invention. It is the figure which removed the part of the conveyance tool from the binarized image of this invention. It is a figure which displays a measurement frame on the head and shaft part of the binarized image of the present invention. It is a figure which displays a measurement frame on the screw part of the binarized image of the present invention. It is a figure which displays a measurement frame on the screw thread of the binarized image of the present invention.

  In particular, the inspection method of the present invention includes the conveyance path 10 that conveys the head S <b> 1 of the screw S while supporting the head S <b> 1 of the screw S with the conveyance tool 11 that sandwiches the shaft portion S <b> 2 of the screw S, and the image processing inspection apparatus 50. The inspection method used.

  The conveyance path 10 includes a wire conveyance path using a thin wire as a conveyance tool, a turntable conveyance path using a turntable having a notch on the outer periphery as a conveyance tool, or a round belt conveyance path using a round belt as a conveyance tool. It is a waste. In the example of illustration, the wire conveyance path 10 which conveys the screw S discharged | emitted from the parts feeder P with the conveyance tool 11 of a thin wire is shown (refer FIG. 1).

  The apparatus used in the present invention uses a side camera 20, an illumination device 30, an upper camera 40, and an image processing inspection device 50 in addition to the transport path 10.

  The side camera 20 is a CCD camera that captures an image of the entire screw S from a side surface direction of the transport tool 11 at a predetermined position, and the illumination device 30 is an LED light disposed above the screw S. The upper camera 40 is a CCD camera that images the upper surface of the head S1 of the screw S.

  In order to image the screw S on the transport tool 11, the side camera 20 is disposed on the side surface of the screw S, and the upper camera 40 is disposed above the screw S (see FIG. 2). At this time, the illumination device 30 is arranged above the screw S to illuminate the upper surface of the head S1. The illustrated illumination device 30 uses a donut-shaped LED light, and is configured so that the upper camera 40 captures an image through the center of the donut shape.

  The image processing inspection apparatus 50 is an apparatus that determines by comparing data set in advance with respect to the measurement unit of the screw S and images captured by the cameras. In the present invention, the type of the screw S is set and registered in the image processing inspection apparatus 50. This type of setting registration can be any setting registration such as setting registration based on the basic shape of the screw S, for example. Furthermore, the measurement position of each part is set and registered for each type. For example, the diameter and the height of the head S1, the diameter and the length of the shaft S2, or the diameter and thickness of the washer depending on the presence or absence of the washer.

  The types of screws S are classified into flat heads, pan heads, truss heads, round heads, hexagon heads, and the like according to the shape of the head. Moreover, it is classified into a metric screw, a tapping screw, etc. according to the shape of the screw part. Further, depending on the presence or absence of a washer, there are no washers, plain washers incorporated, spring washers incorporated, plain washers + spring washers incorporated, and the like. In addition, there are various screw sizes such as the overall length, the nominal diameter of the screw, the diameter of the washer, the thickness of the washer, and the shape of the screw tip, such as a flat tip and a pointed tip. These types are registered in the image processing inspection apparatus 50, and the type of the screw S displayed on the inspection screen 51 is determined (see FIG. 3).

  That is, the entire image of the screw S imaged by the side camera 20 is binarized and displayed on the entire screen 53 (see FIG. 3). On the other hand, an image captured by the upper camera 40 is displayed on the upper screen 52. The type of the screw S is determined based on these images.

  The entire image of the screw S imaged by the side camera 20 is binarized so that the head S1 and the shaft S2 become clear (see FIG. 6). In this binarized image, the shadow of the transport tool 11 is reflected, but because it is located at the boundary between the head S1 and the shaft S2, the length of the entire head S1 and the shape of the shaft S2 are shown. The length and thickness of the shaft portion S2 can be sufficiently determined (see FIG. 7). Therefore, the combination of the upper head S1 shape and the lower shaft portion S2 shape with the carrier 11 as a boundary from this binarized image and the type of screw S from the upper surface shape of the head S1 imaged by the upper camera 40. Can be determined.

  The binarized image displayed on the overall screen 53 of the inspection screen 51 displays a rectangular measurement frame T that encloses the measurement positions of the respective parts set and registered in advance according to the determined type of the screw S. . The measurement frame T has a rectangular shape composed of a vertical line and a horizontal line, is in contact with the edge portion of the measurement position, and is automatically measured based on the coordinates in the measurement frame T. Each data automatically measured for each measurement frame T is displayed on the data screen 54, and this data is used as product data (see FIGS. 4 and 5).

  The data screen 54 shown in FIG. 4 displays the data of the head S1 and the shaft portion S2 of the screw S. That is, the diameter and height of the head S1, the total length of the shaft portion S2, the neck length, the inclination, and the like. When the inclination of the shaft portion S2 is detected in this way, the determination is made in a state in which the inclination is corrected at the time of determination by the image processing inspection apparatus 50. Further, the data screen 54 shown in FIG. 5 displays data of a type in which a washer is incorporated in the screw S. In addition to the data of the head S1 and the shaft S2, the diameter, thickness, area, etc. of the washer are displayed. The data of is also displayed.

  After the data automatically measured in the captured image is set in the image processing inspection apparatus 50 as product data, the screws S sequentially transported by the transport tool 11 are similarly imaged and compared with the product data. Judge the quality of the.

  At this time, the screw S to be imaged for registering product data selects and images a regular product in advance. It is also possible to continuously image a plurality of screws S and use the average value as product data.

  FIG. 8 shows the position of the measurement frame T when automatically measuring the diameter and height of the head S1 and the diameter and length of the shaft S2. That is, since the top of the carrier 11 is recognized as the head S1, the diameter and height of the head S1 are automatically measured in the measurement frame T that surrounds the entire binarized head S1, and the product data To do.

  On the other hand, since the lower part of the transport tool 11 is recognized as the shaft part S2, the diameter and length of the shaft part S2 are automatically measured by the measurement frame T that encloses the entire shape of the binarized shaft part S2, and the product data And

  FIG. 9 shows a measurement frame T that encloses the screw portion S3 from the shape of the shaft portion S2 that has been binarized. With this measurement frame T, the length and diameter of the threaded portion S3 are automatically measured to obtain product data.

  FIG. 10 shows a pair of measurement frames T surrounding the left and right screw threads S4 from the binarized shaft portion S2 shape. In these pair of measurement frames T, edge processing is performed by density projection of the binarized image within each measurement frame T, and the pitch of the thread S4 is automatically measured from the contour position of the valley of each thread S4 to obtain product data and To do.

  Since the measurement position of the measurement frame T is set and registered in advance according to the type of the screw S, the display position of the measurement frame T is not limited to the illustrated example.

P parts feeder S screw S1 head S2 shaft part S3 screw part S4 screw thread T measurement frame 10 transfer line 11 transfer wire 20 side camera 30 illumination device 40 upper camera 50 image processing inspection device 51 inspection screen 52 upper screen 53 for the whole Screen 54 Data screen

Claims (5)

A conveying path for conveying the screw while supporting the head in a hanging manner with the shaft portion sandwiched by the conveying tool, a side camera for imaging the entire screw from the side surface direction of the conveying tool at a predetermined position, and an upper surface of the screw head In a screw inspection method using an upper camera to be imaged and an image processing inspection apparatus for processing an image of each camera,
The image of the entire screw imaged by the side camera is binarized, and the combination of the upper head shape and the lower shaft shape with the carrier as the boundary from this binarized image, and the head imaged by the upper camera The type of screw is determined from the top surface shape of
A binarized image is displayed on the inspection screen of the image processing inspection apparatus, and a rectangular measurement frame that surrounds the measurement positions of the respective parts set and registered in advance according to the determined screw type is displayed. A screw inspection method, wherein each piece of data automatically measured for each frame is used as product data, and the quality of the screw is determined based on the product data.   The screw inspection according to claim 1, wherein in the inspection method, the diameter and height of the head are automatically measured in the measurement frame that encloses the entire binarized head shape to obtain the product data. Method.   The screw inspection method according to claim 1, wherein in the inspection method, the length of the shaft portion is automatically measured by the measurement frame that encloses the entire binarized shape of the shaft portion to obtain the product data.   The screw inspection according to claim 1, wherein in the inspection method, the length and diameter of a screw part are automatically measured in the measurement frame that encloses the screw part from the binarized shape of the shaft part to obtain the product data. Method.   In the inspection method, the left and right screw threads are surrounded by the measurement frames from the binarized shaft portion shape, and edge processing is performed by density projection of the binarized image in each measurement frame. The screw inspection method according to claim 1, wherein the thread pitch is automatically measured from the contour positions of the peaks and valleys to obtain the product data.

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