JP2015175652A - Nut attachment presence/absence inspection device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a nut attachment presence/absence inspection device capable of determining the attachment presence/absence of a nut attached to the back surface side of a workpiece from the front surface side of the workpiece.SOLUTION: A CCD camera 2 photographs a region including a pierce hole 10a on the front surface side of a press molded article 10. Each LED light source 3 is disposed on a side of the CCD camera 2, and radiates light to the region including the pierce hole 10a on the front surface side of the press molded article 10. A control unit 4 determines the attachment presence/absence of the nut 11 by comparing a calculation result of the region corresponding to the pierce hole 10a in a photographic image W by the CCD camera 2 with a previously set value.

Description

  The present invention relates to a nut attachment presence / absence inspection apparatus that determines whether or not a nut is attached to a workpiece.

  2. Description of the Related Art Conventionally, automobiles have been completed by assembling a plurality of panel-shaped press-formed products into a body body, and attaching various parts to the body body. Various parts are attached to the vehicle body by, for example, fastening with bolts and nuts, and the nut is often attached to the vehicle body with a so-called weld nut by welding.

  In a body body production line, an operator visually determines whether or not the nut is attached to the body body. However, since the visual determination by the operator is very complicated, in order to avoid this, for example, it is determined whether or not the nut is attached to the vehicle body using the inspection device disclosed in Patent Document 1. Can be considered. The inspection apparatus of Patent Document 1 photographs parts mounted on the surface of a press-formed product with two cameras from different angles, and compares the photographed images with preset reference data to determine whether or not a nut is attached. ing.

  By the way, the nut is attached to the back side of the press-molded product so that the screwing hole of the nut corresponds to the through-hole formed in the press-molded product, and is located inside the vehicle body when it becomes the vehicle body. There is a case.

JP-A-10-73419

  However, the inspection apparatus of Patent Document 1 determines whether or not the various parts are attached by directly photographing the various parts attached to the press-molded product with a camera. A nut is provided inside the vehicle body as described above. If it is located and the camera cannot be inserted inside the vehicle body, it cannot be determined whether or not the nut is attached. Even if the nut is not located inside the body of the vehicle body, the camera cannot be positioned on the back side of the press-molded product due to the configuration of the production line, and the back side of the press-molded product can be photographed with the camera. When it is necessary to change the posture of the press-molded product, the line tact increases due to the posture changing operation.

  The present invention has been made in view of such points, and an object of the present invention is to provide a nut mounting presence / absence inspection device that can determine whether or not a nut attached to the back side of a workpiece is attached from the surface side of the workpiece. There is to do.

  In order to achieve the above object, the present invention is characterized in that it is possible to determine whether or not a nut is attached by utilizing the fact that light is diffusely reflected by the screw thread of the nut when light is applied to the screwing hole of the nut. And

  Specifically, a nut mounting presence / absence inspection is performed to determine whether or not the nut attached to the back surface side of the work is attached to the through hole formed in the panel-like work from the work surface side. In the apparatus, the following solutions were taken.

  That is, in the first invention, a camera that captures an area including the through hole on the workpiece surface side, and a light that is disposed on the side of the camera and irradiates the area including the through hole on the workpiece surface side. A light source; and a determination unit that determines whether or not the nut is attached by comparing a calculation result of a region corresponding to the through hole of the image captured by the camera with a preset setting value. To do.

  In a second invention, in the first invention, the determination means calculates a color intensity of each pixel in an area corresponding to the through hole of the photographed image, and an area having a color intensity equal to or greater than a preset setting value. It is configured to determine whether or not the nut is attached depending on whether or not there is.

  According to a third invention, in the first or second invention, a plurality of the light sources are provided at equidistant positions around the camera.

  In the first invention, when the through hole of the work is photographed from the front side of the work by the camera, the light from the light source that is irradiated obliquely with respect to the photographing direction of the camera and passes through the through hole is attached to the back side of the work It is irregularly reflected by the unevenness of the screwed hole of the nut. Therefore, in the region corresponding to the through hole in the photographed image, there is a difference between the region of irregular reflection due to the light from the light source and the other region. Therefore, it is possible to attach the nut on the back side of the workpiece by comparing with a preset set value. Presence / absence can be determined.

  In the second invention, the determination processing is performed by using the color intensity data of each pixel of the captured image as it is, so that it is not necessary to perform complicated calculation processing, and the calculation load of the determination means can be reduced.

  In the third invention, since light is irradiated to the entire circumference of the screwing hole of the nut attached to the back surface side of the work, the inner peripheral surface of the screwing hole of the nut is always in a state where the nut is attached to the back surface side of the work It is possible to obtain a photographed image with irregular reflection, and to reliably determine whether or not a nut is attached.

(A) is a figure which shows the whole structure of the test | inspection apparatus which concerns on embodiment of this invention, (b) is A arrow directional view. It is the figure which image | photographed the area | region around the piercing hole of the press molded product with which the nut was attached to the back surface side from the surface side. It is the schematic which expanded the B section of FIG. 2 and exaggerated each pixel.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The following description of the preferred embodiment is merely exemplary in nature.

  FIG. 1 shows a nut mounting presence inspection device 1 of the present invention. The inspection device 1 is arranged on a production line in which a vehicle bracket (small part) (not shown) is assembled to a press-formed product 10 (workpiece) having a cross-sectional hat shape (panel shape), and the pierce formed on the press-formed product 10 Whether the nut 11 attached to the back side of the press-molded product 10 is attached so that the screwing hole 11a of the nut 11 corresponds to the hole 10a (through hole) is determined from the front side of the press-molded product 10. ing.

  The press-molded product 10 is held at the tip of the arm portion 12 of a general-purpose robot (not shown) so that the surface side faces upward.

  Above the press-molded product 10, the CCD camera 2 is arranged so that the photographic lens faces directly below. The CCD camera 2 photographs the region including the pierce hole 10a on the surface side of the press-molded product 10 from above. It has become.

  On the side of the CCD camera 2, four LED light sources 3 are arranged at equal intervals around the CCD camera 2 in plan view, and the LED light sources 3 pass through the pierce holes 10 a on the surface side of the press-molded product 10. The region including the light is irradiated obliquely from above, and the irradiated light is irregularly reflected by the unevenness of the screw hole 11 a in the nut 11.

  A controller 4 (determination means) is connected to the CCD camera 2 and the LED light sources 3.

  As shown in FIGS. 2 and 3, the control unit 4 takes a photographed image W of the press-molded product 10 photographed by the CCD camera 2, and based on the photographed image W, the back side of the press-molded product 10. It is determined whether or not the nut 11 is attached.

  The control unit 4 includes a calculation unit 4a that calculates the captured image W and a storage unit 4b that stores a preset setting value. The calculation unit 4a corresponds to the pierce hole 10a of the captured image W. It is determined whether or not there is a region R that is irregularly reflected by comparing the calculation result of the region to be compared with the set value stored in the storage unit 4b.

  Specifically, as shown in FIG. 3, the calculation unit 4a extracts a pixel group P in a region corresponding to the piercing hole 10a in the captured image W, and first, an outer peripheral portion of the piercing hole 10a of the pixel group P. The color intensity (R value + B value + G value) of each pixel continuous in a certain direction (V direction in FIG. 3) from the pixel P1 at a predetermined position corresponding to is sequentially calculated. Next, when the calculation of each pixel in a line aligned in the V direction from the pixel P1 is completed, the calculation of each pixel aligned in a line in the V direction is performed from the pixel P2 adjacent to the pixel P1. After that, the calculation of each pixel arranged in a line in the V direction is sequentially performed from the pixels P3, P4... Adjacent to the pixels P1 and P2.

  And when the said control part 4 finds what is more than the preset value in the value of each pixel of the pixel group P calculated by the said calculating part 4a (when the area | region which is irregularly reflected is found), the point Thus, the calculation is terminated, and it is determined that the nut 11 is attached to the back side of the press-formed product 10.

  On the other hand, when the control unit 4 has all the pixels of the pixel group P in the region corresponding to the piercing hole 10a in the captured image W less than a preset value, the nut 11 is placed on the back side of the press-formed product 10. It is determined that it is not attached.

  That is, the control unit 4 calculates the color intensity of each pixel P in the area corresponding to the piercing hole 10a of the photographed image W, and determines whether there is an area having a color intensity equal to or higher than a preset value. Whether or not the nut 11 is attached is determined.

  As described above, according to the embodiment of the present invention, when the piercing hole 10a of the press-molded product 10 is photographed from the surface side of the press-molded product 10 by the CCD camera 2, it is irradiated obliquely with respect to the photographing direction of the CCD camera 2. The light from the LED light source 3 passing through the piercing hole 10a is irregularly reflected by the unevenness of the screwing hole 11a of the nut 11 attached to the back surface side of the press-formed product 10. Accordingly, in the region corresponding to the piercing hole 10a in the photographed image W, a difference occurs between the region of irregular reflection due to the light from the LED light source 3 and the other region, so that the press molded product is compared with a preset set value. Whether or not the nut 11 is attached on the back surface side of the ten can be determined.

  In addition, since the determination process is performed using the color intensity data of each pixel of the captured image W as it is, it is not necessary to perform a complicated calculation process, and the calculation load on the control unit 4 can be reduced.

  Further, since light is irradiated to the entire circumference of the screwing hole 11a of the nut 11 attached to the back surface side of the press-formed product 10, in a state where the nut 11 is attached to the back surface side of the press-formed product 10, A photographed image W in which the inner peripheral surface of the screw hole 11a of the nut 11 is irregularly reflected can be obtained, and the presence or absence of the nut 11 can be reliably determined.

  In the embodiment of the present invention, the CCD camera 2 is used to image the area including the pierce hole 10a on the surface side of the press-molded product 10, but the image may be captured using a CMOS camera.

  In the embodiment of the present invention, the four LED light sources 3 are arranged around the CCD camera 2. However, the present invention is not limited to this, and one to three LED light sources 3 may be arranged around the CCD camera 2. Alternatively, five or more LED light sources 3 may be arranged.

  Furthermore, in the embodiment of the present invention, the color intensity data of each pixel of the photographed image W is calculated and compared with a preset setting value to determine whether or not the nut is attached. For example, the presence / absence of the nut may be determined by binarizing the captured image W and comparing it with a preset set value.

  In addition, although the LED type light source is used in the embodiment of the present invention, illumination may be performed with a light source other than the LED type.

  Note that the color intensity data used when determining whether or not the nut 11 is attached may be obtained by using only the R value for the determination process, or by using all the R value, B value, and G value for the determination process. May be performed.

  The present invention is suitable for a nut attachment presence / absence inspection apparatus that determines whether or not a nut is attached to a workpiece.

DESCRIPTION OF SYMBOLS 1 Nut attachment presence inspection apparatus 2 CCD camera 3 LED light source 4 Control part (determination means)
10 Press-formed product (work)
10a Piercing hole (through hole)
11 Nut 11a Screwing hole W Photographed image P Pixel

Claims (3)

A nut mounting presence / absence inspection device that determines whether or not the nut attached to the back side of the work is attached to the through hole formed in the panel-like work from the work surface side,
A camera for photographing an area including the through hole on the workpiece surface side;
A light source disposed on the side of the camera and irradiating light to a region including the through hole on the workpiece surface side;
A nut mounting comprising: a determination unit that determines whether or not the nut is mounted by comparing a calculation result of a region corresponding to the through hole of the photographed image by the camera and a preset setting value. Presence inspection device. In the nut mounting presence / absence inspection device according to claim 1,
The determination means calculates the color intensity of each pixel in the area corresponding to the through-hole of the photographed image, and determines whether the nut is attached or not depending on whether there is an area having a color intensity equal to or higher than a preset value. A nut mounting presence / absence inspection device characterized by being configured to determine. In the nut mounting presence / absence inspection device according to claim 1 or 2,
A nut mounting presence / absence inspection device, wherein a plurality of the light sources are provided at equal intervals around the camera.