JP5017628B2 - Side inspection device - Google Patents

Description

  The present invention relates to a side surface inspection apparatus capable of efficiently and accurately inspecting the entire circumference of side surfaces of bolts, nuts, machine parts and the like (hereinafter referred to as inspection objects) using a single CCD camera. In addition to quality inspection, the inspection referred to here includes confirmation inspection such as whether protrusions, grooves, and the like are formed on the side surface as designed, or whether marking is performed as designed.

  Patent Documents 1 to 3 listed below disclose an inspection apparatus that efficiently images the entire circumference of the side surface of the object to be inspected by a single camera and performs the entire circumference inspection of the side surface.

  In the inspection apparatuses of Patent Documents 1 and 3, a cone prism is arranged between the object to be inspected and the CCD camera, and the side surface of the object to be inspected is viewed through the cone prism so that the entire side surface of the inspection object is surrounded. Simultaneous imaging is possible. The CCD camera is positioned directly above the object to be inspected, and a cone prism is disposed coaxially with the center of the field of view of the camera, and the object to be inspected is disposed below the cone prism. Further, the illumination of the side surface of the inspection object is performed by arranging an annular light source around the field of view of the camera, and these configurations are common.

  The inspection apparatus of Patent Document 2 may be considered as a replacement of the cone prism of Patent Documents 1 and 3 with a conical reflecting mirror. The principle of the entire circumference inspection of the side surface and the method of illumination of the side surface are described in Patent Document 1, There is not much difference from the inspection equipment of 3.

Japanese Patent No. 3014684 Japanese Patent No. 3770611 JP-A-9-304285

  The above-described conventional inspection apparatus is difficult to obtain an image that is clear and has an appropriate observation direction, and cannot meet the demand for advanced inspection. Some of the inspected objects include parts for vehicles that require high reliability, and all such parts are inspected, and it is required to detect defects that are difficult to find, such as scratches and cracks. Is done.

  In order to meet this requirement, a clear image of the surface to be inspected with little distortion is required. However, the inspection apparatus disclosed in Patent Document 1 cannot obtain an image that meets the requirement and can be used for detecting scratches and cracks. There wasn't. In the inspection apparatus of Patent Document 1, a light source for illumination is arranged on the outer periphery of a cone prism, and it is considered that light from the light source is reflected by the cone prism toward the camera and blurs the image.

  The inspection apparatus of Patent Document 2 is also concerned about the following. That is, in the inspection apparatus of Patent Document 2, as shown in FIG. 1 of the same document, the illumination light source is disposed between the cone prism and the object to be inspected. The distance increases and the side surface of the object to be inspected is seen from obliquely above. Although it is easier to find fine scratches and cracks by observing the side from the side, it cannot meet the requirements. For this reason, the accuracy of the inspection becomes rough even if the correcting means for correcting the deformation of the image described in the document is included.

  As disclosed in Patent Document 3, the object to be inspected can be brought closer to the cone prism by disposing the illumination light source below the object to be inspected. When the inspection is performed while being transported, it is not allowed to place the light source below the object to be inspected due to the problem of light shielding by the transport surface. The light source is not allowed to prevent the movement of the object to be inspected, and due to this restriction, the inspection apparatus of Patent Document 2 has to place the light source between the object to be inspected and the cone prism as shown in FIG. Cause the above problem. If the light source is arranged so as to partially overlap the outer periphery of the cone prism and the inspection object is brought close to the cone prism, the illumination light from the light source does not strike the side surface of the inspection object well. The illumination failure caused by this also makes the image unclear, so this structure does not solve the above problem.

  The present invention enables a side inspection apparatus to perform a full-round inspection of a side surface of an object to be inspected efficiently and accurately by using a single CCD camera so that a clear and observable image can be obtained. The challenge is to do so.

In order to solve the above-described problems, in the present invention, an outer surface of a part placed on the transport surface of the inspection object to be sent to the inspection unit in a state where at least a part is placed on the transport surface is imaged with a camera. The side inspection apparatus to be inspected was configured as follows.
That is, the outer diameter surface of the vertical cylinder, the upper side concentric with the outer diameter surface has a small-diameter tapered inner diameter surface, and flat upper and lower surfaces, and the outer diameter surface is configured as a mirror surface that totally reflects light inwardly. Further, the inner diameter surface is configured as a prism surface that transmits light perpendicular to the surface and guides the light to the outer diameter surface of the mirror surface, and re-reflects the light reflected by the outer diameter surface upward. A cone lens,
A camera provided below and below the cone lens,
An annular light source provided between the cone lens and the camera and configured to output illumination light in a radial direction from the outer periphery toward the lens center; and the cone lens and the camera in proximity to the cone lens; And a half mirror inclined at 45 degrees that guides the illumination light from the annular light source to the anti-camera side and guides it to the cone lens ,
The cone lens, camera and annular light source are arranged coaxially with the center of the inspection part,
Illumination light from the annular light source is passed through the cone lens, is reflected in turn by the inner diameter surface of the prism surface and the outer diameter surface of the mirror surface, and is guided to the inspection unit directly below the cone lens, and at least a part of the illumination light is a conveyance surface Illuminating the outer peripheral side surface of the portion placed on the transport surface of the inspection object to be sent to the inspection unit in a state of being placed on the outer peripheral surface of the mirror surface, A structure is adopted in which the light is sequentially reflected by the inner diameter surface of the prism surface and taken into the camera.
The inspection object is introduced onto the inspection unit after being positioned on the transport surface so that the center of the side surface to be inspected coincides with the center of the inspection unit.

  This inspection apparatus displays an image processing apparatus that processes the obtained image, a determination circuit that determines the quality of a side surface that has been inspected by comparing the processed image data with a reference value, and the obtained image and the determination result. The display device etc. to be included. These are not elements that characterize the present invention, but may be the same as those employed in conventional inspection apparatuses.

  When this side inspection device is used with the arrangement and orientation of the camera, cone lens, and annular light source reversed, at least a part of the inspection object to be sent to the inspection unit is suspended below the conveyance surface. The entire circumference of the outer surface of the portion suspended below the conveyance surface can be inspected.

Preferred configurations of the side surface inspection apparatus are listed below.
(1) An antireflection film for preventing reflection of visible light is provided on an end surface of the cone lens facing the camera.
(2) As the camera, a camera whose imaging lens is a telecentric lens is provided.

  In the side surface inspection apparatus according to the present invention, an annular light source for illumination is disposed between a camera and a cone lens, illumination light from the annular light source is passed through the inside of the cone lens, and a prism surface having an inner diameter of the lens and an outer diameter of the lens are disposed. Since it is sequentially reflected on the mirror surface and guided to the outer periphery of the inspection object introduced into the inspection section, the inspection object can be sufficiently close to the cone lens to observe the side surface of the inspection object from a position where the amount of axial deviation is small. Is possible.

  Further, the outer diameter surface of the cone lens is configured as a mirror surface that totally reflects light, and unnecessary light does not pass through the outer diameter surface and enter from the outside. Therefore, the blurring phenomenon of the image that is a problem in the apparatus of Patent Document 1 is also prevented. By guiding the illumination light to the inspection unit via the cone lens, the light source can be placed above the cone lens to provide uniform illumination of the side of the object to be inspected. The required advanced inspection is possible.

  Since the annular light source is placed above the cone lens (the camera is facing upward and below the cone lens), there is no problem that the illumination light is blocked by the conveyance surface of the conveyance device. It is possible to efficiently inspect while continuously transporting an object to be inspected using a transport device constituted by an opaque rotating disk or a transport belt.

  The device of (1) above uses a half mirror, reflects the illumination light with the half mirror, and guides it to the cone lens. The light source is placed outside the field of view (image transmission path) of the camera, and the image is reflected by the light source. It can be hidden and lens flare (halation) that blurs the image is also prevented. Therefore, more stable inspection is possible.

  When a half-mirror is provided with a cylindrical inner surface and a light-shielding film is provided on the inner surface, light from the light source that has passed through the mirror surface is blocked by the light-shielding film and begins to leak toward the mirror surface at the opposite position. There is nothing. For this reason, the phenomenon that light is reflected to the camera side does not occur on the mirror surface at the opposite position, and the image projected by the camera becomes clearer.

  A half mirror whose mirror surface is inclined at an angle of 45 degrees is preferable because a reflection loss of illumination light is suppressed to a small value.

  In addition, an image having an antireflection film on the end surface of the cone lens facing the camera can obtain an image with little influence of reflected light. An image pickup lens using a camera that is a telecentric lens (a well-known lens that has a focal point inside and can obtain a light beam that can be regarded as parallel to the optical axis and suppresses distortion of the image) is image distortion. These are also useful for increasing the inspection accuracy.

Embodiments of the present invention will be described below with reference to FIGS. FIG. 1 shows an outline of an example of the side surface inspection apparatus of the present invention. The side inspection apparatus shown in the figure includes a camera (CCD camera) 1, a cone lens 2, an annular light source 3 for illumination, and an optical system that combines a half mirror 4 that redirects light from the annular light source 3, and a camera 1. An image processing device 7 that processes the captured image, a determination circuit 8 that determines whether or not the side surface is inspected by comparing the processed image data with a reference value, determines the presence or absence of an element to be placed on the side surface, and the like. A display device 9 for displaying the obtained image and the determination result is included. The image processing device 7, the discrimination circuit 8, and the display device 9 may be well known. The image processing apparatus 7 can include a correction circuit that corrects image deformation and the like as necessary.
In FIG. 1, reference numeral 5 denotes a light shielding film, and 6 denotes an antireflection film.

  The camera 1 is a camera using a telecentric imaging lens. The camera 1 is held at a fixed position in a posture facing directly downward.

  The cone lens 2 includes an outer diameter surface 2a of a vertical cylinder, a concentric inner diameter surface 2b concentric with the outer diameter surface 2a and inclined in a direction of decreasing the diameter on the upper side, and flat upper and lower surfaces 2c and 2d perpendicular to the axis. Have. The cone lens 2 is configured as a mirror surface in which an outer diameter surface 2a totally reflects light inward, and further, the inner diameter surface 2b transmits light in a direction perpendicular to the surface so that the outer diameter surface 2a is a mirror surface. The side surface of the part placed on the transport surface 10a of the object A to be inspected (the figure shows the head of the bolt) ) Is reflected on the camera 1 through this lens.

  The annular light source 3 is a light source having a size that surrounds the field of view of the camera 1 from the outside, and a light source that irradiates illumination light radially inward is used.

  The half mirror 4 has an inverted frustoconical shape having an outer diameter surface 4a and an inner diameter surface 4b of a straight cylinder inclined at an angle of 45 degrees in the direction of decreasing the diameter on the lower side (inclination angle with respect to a horizontal plane or a vertical plane). A ring-shaped mirror is used. In the half mirror 4, the inclined outer diameter surface 4 a is configured as a mirror surface that reflects the illumination light from the annular light source 3 downward and guides it to the upper surface of the cone lens 2. The outer diameter surface 4a of the mirror surface is configured to semi-transmit light, and the image of the side surface of the inspection object that appears on the upper surface 2c of the cone lens 2 passes through the outer diameter surface (mirror surface) 4a. Is reflected on camera 1.

  A region surrounded by the inner diameter surface 4 b of the half mirror 4 is a space that constitutes an image transmission path, and the top surface of the inspection object A can be directly viewed by the camera 1. This structure is preferable because it enables simultaneous inspection of the side surface and the top surface, but the inspection function of the top surface of the object to be inspected (directly looking at the top surface with the camera 1) is not essential.

  The light shielding film 5 is formed on the inner diameter surface 4 b of the half mirror 4. The antireflection film 6 is provided on the upper surface 2 c of the cone lens 2. This antireflection film 6 is a film for preventing reflection of visible light to the camera 1 side, such as a film formed by reacting a chemical substance or a film to which fine particles are added, such as an optical lens or glasses. A film generally used for a lens or the like may be used.

  In the side surface inspection apparatus including the above elements, the camera 1, the cone lens 2, the annular light source 3, and the half mirror 4 are arranged coaxially with the center C of the inspection unit B.

  Inspection by this apparatus is performed by positioning and holding the inspection object A on the conveyance surface 10a of the conveyance apparatus 10 and introducing the inspection object A into the inspection unit B. The light from the annular light source 3 is reflected and guided to the inspection section B in the order of the half mirror 4, the inner diameter surface (prism surface) 2b of the cone lens 2, and the outer diameter surface (mirror surface) 2a.

  When the inspection object A moves to the inspection unit B, the side surface As of the portion of the inspection object A placed on the transport surface 10a is reflected on the outer diameter surface (mirror surface) 2a of the cone lens 2, and the image is displayed. The light is reflected toward the inner diameter surface (prism surface) 2 b, and then further reflected toward the camera 1. As shown in FIG. 2, the image of the side surface As thus obtained is a ring-shaped image in which the upper end E1 of the side surface As appears on the inner diameter side and the lower end E2 appears on the outer diameter side. In the case of the illustrated apparatus, the camera 1 also directly views the top surface of the inspection object A, and the side image is displayed as a ring-shaped image around the image of the top surface.

  The image captured by the camera 1 when the center of the inspection object A comes to the center C of the inspection part B is an image of the side surface As around the top surface image. The image is projected by the camera 1 and sent to the image processing device 7, and the processed image data is sent to the discrimination circuit 8 where it is compared with the reference value. Make a decision. Then, the image projected by the camera 1 and the inspection result are displayed on the screen of the display device 9.

  In the illustrated side surface inspection apparatus, part of the light from the annular light source 3 passes through the half mirror 4, but the transmitted light is blocked by the light shielding film 5 and therefore does not reach the mirror surface at the opposite position. Therefore, reflection of light toward the camera 1 on the mirror surface at the opposite position is prevented, and the sharpness of the camera image does not deteriorate.

  By providing a light-shielding film 5 on the inner diameter surface 4b of the half mirror 4, light from the annular light source 3 that has passed through the outer diameter surface (mirror surface) 4a is blocked to prevent light from leaking to the mirror surface at the opposite position. can do. Therefore, the leaked light is not reflected to the camera 1 side on the mirror surface at the opposite position, and the image captured by the camera 1 becomes clearer.

  Further, by providing the antireflection film 6 on the upper surface 2c of the cone lens 2, the reflection of the illumination light reflected by the half mirror 4 toward the inspection section toward the camera 1 side on the cone lens is suppressed. Also improves the quality of the image captured by the camera 1.

  In addition, since the camera 1 is a camera using a telecentric lens, the image is less distorted and an image that can be easily identified such as a scratch can be obtained and the inspection accuracy can be improved.

  An example in which the side surface inspection apparatus of the present invention is used for inspection of the head of a shaft body with a head including a bolt is shown in FIGS. Reference numeral 10 in the figure denotes a conveying device (in the figure, a rotary table). As for this conveyance apparatus (rotary table) 10, the outer peripheral upper surface is comprised as the conveyance surface 10a. The side surface inspection apparatus shown in the figure includes this conveyance apparatus 10, a feeder 11 that supplies the inspection object A (bolts in the figure) to the conveyance apparatus 10, a conveyance guide 12, unshown non-defective product dispensing apparatus and defective product dispensing apparatus (this). Etc. are not shown).

  The illustrated conveying apparatus 10, that is, the rotary table, is driven by a motor (not shown) and rotates around a vertical axis. Notch grooves 10b are provided at a constant pitch on the outer periphery of the rotary table, and the neck portion of the inspection object A is inserted into the notch grooves 10b, and the inspection object A is suspended by supporting the head with the conveying surface 10a. . The inspection object A is conveyed by rotating the table while preventing the removal from the notch groove 10b by the conveyance guide 12, and a portion (for example, a portion placed on the conveyance surface 10a in the inspection section B provided in the middle of the conveyance path (for example, Inspect the outer circumference and top surface of the bolt head. In the center of the inspection part B, optical system elements characterizing the present invention are provided in a concentric arrangement.

  The optical system elements, that is, the camera 1, the cone lens 2, the annular light source 3, and the half mirror 4 are held by a holder 16 that is attached to a stand 13 so that the height can be adjusted using height adjusting mechanisms 14 and 15. The installation height of each element can be adjusted according to the size of the inspection object A. By making the height of the cone lens 2 adjustable, the cone lens 2 can be as close as possible to the inspection object A, and the side surface As can be observed from a position where the amount of axial displacement is small. It becomes possible to cope with a change in the height dimension of the portion placed on the A conveying surface 10a.

  When the inspection object A is carried into the inspection unit B, the top surface and the side surface (outer peripheral surface) of the head of the inspection object A are imaged by the camera 1 and the surface quality is inspected. Then, the inspection object A determined to be defective by the inspection is discharged from the transport path by the defective product dispensing device, and only the non-defective product is transported to the end of the transport path and taken out of the transport device by the non-defective product dispensing device.

2 and 3 inspects the side surface of the inspection object A such as the head disposed on the conveyance surface 10a. As shown in FIG. 5, the camera 1 and the cone lens 2 are inspected. When these elements are arranged below the conveying surface 10a with the arrangement and orientation of the annular light source 3 reversed, the object A is suspended and conveyed by the conveying device 10, and the conveying surface is in the middle thereof. It is possible to inspect the entire circumference of the side surface of the portion suspended below, for example, the outer peripheral surface of the shaft portion of the bolt.
The side surface inspection apparatus according to this embodiment is capable of high-speed conveyance of an inspection object by the conveyance device 10. By using such a transfer device capable of high-speed transfer, it is possible to increase the inspection speed, and it is possible to realize and provide an inspection apparatus capable of performing high-speed, efficient and accurate inspection of the entire circumference of the side surface. .

  The inspected object may be a nut without a shaft portion. An object to be inspected such as a nut without a shaft portion can be transported by a belt conveyor or the like. Even when such a transport device is used, the arrangement of the illumination light source is restricted (below the transport surface). Therefore, the inspection apparatus of the present invention is effective.

The figure which shows the outline | summary of 1st form of the side surface inspection apparatus of this invention The figure which shows typically the image of the side and the top of the inspection object imaged with the camera Side view of the embodiment of the side inspection apparatus of the present invention Plan view of the side inspection apparatus of FIG. The figure which shows the outline | summary of 2nd form of the side surface inspection apparatus of this invention

Explanation of symbols

1 Camera 2 Cone Lens 2a Outer Diameter Surface (Mirror Surface)
2b Inner diameter surface (prism surface)
3 annular light source 4 half mirror 4a outer diameter surface 4b inner diameter surface 5 light shielding film 6 antireflection film 7 image processing device 8 discriminating circuit 9 display device 10 transport device 10a transport surface 10b notch groove 11 feeder 12 transport guide 13 stands 14 and 15 Height adjustment mechanism 16 Holder A Inspected object As Side E1 Upper end E2 Lower end B Inspection part C Center of inspection part

Claims (4)

The outer surface of the part placed on the transport surface (10a) of the inspection object (A) sent to the inspection unit (B) in a state where at least a part is placed on the transport surface (10a) is imaged with a camera. A side inspection device for inspecting
The outer diameter surface (2a) of the vertical cylinder, the tapered inner diameter surface (2b) inclined in the direction of decreasing the diameter on the upper side of the outer diameter surface (2a), and the upper and lower surfaces (2c, 2d) perpendicular to the axis ), And the outer diameter surface (2a) is configured as a mirror surface that totally reflects light inward, and the inner diameter surface (2b) transmits light perpendicular to the surface to transmit the light. A cone lens (2) configured as a prism surface that leads to the outer diameter surface (2a) of the mirror surface and re-reflects the light reflected by the outer diameter surface (2a) upward;
A camera (1) provided below the cone lens (2) and facing downward;
An annular light source (3) provided between the cone lens (2) and the camera (1) and configured to output illumination light in a radial direction from the outer periphery toward the lens center ;
The cone lens is disposed between the cone lens (2) and the camera (1) in the vicinity of the cone lens (2), and reflects the illumination light from the annular light source (3) toward the opposite camera side. It has a half mirror (4) inclined at 45 degrees leading to (2) ,
Furthermore, the half mirror (4) has an inner diameter surface (4b) of a straight cylinder and a light shielding film (5) provided on the inner diameter surface (4b),
The cone lens (2), the camera (1), and the annular light source (3) are arranged coaxially with the inspection center (C),
Illumination light from the annular light source (3) is passed through the cone lens (2) and is reflected in turn by the inner diameter surface (2b) of the prism surface and the outer diameter surface (2a) of the mirror surface, and the inspection section directly below the cone lens. (B) of the part placed on the transport surface (10a) of the inspection object (A) sent to the inspection section (B) in a state where at least a part is placed on the transport surface (10a). The outer side surface (As) is illuminated with the illumination light, and the image of the entire circumference of the side surface is sequentially reflected by the outer diameter surface (2a) of the mirror surface and the inner diameter surface (2b) of the prism surface. Side inspection device characterized in that it is incorporated into (1). The outer surface of the part suspended below the conveyance surface (10a) of the inspection object (A) sent to the inspection unit (B) in a state where at least a part is suspended below the conveyance surface (10a) is captured by a camera. A side inspection device for imaging and inspecting,
The outer diameter surface (2a) of the vertical cylinder, the tapered inner diameter surface (2b) inclined in the direction of decreasing the diameter below the outer diameter surface (2a), and the upper and lower surfaces (2c, 2d), the outer diameter surface (2a) is configured as a mirror surface that totally reflects light inward, and the inner diameter surface (2b) transmits light perpendicular to the surface. A cone lens (2) configured as a prism surface that leads to the outer surface (2a) of the mirror surface and re-reflects the light reflected by the outer surface (2a) downward;
A camera (1) provided below the cone lens (2) and facing upward,
An annular light source (3) provided between the cone lens (2) and the camera (1) and configured to output illumination light in a radial direction from the outer periphery toward the lens center ;
The cone lens is disposed between the cone lens (2) and the camera (1) in the vicinity of the cone lens (2), and reflects the illumination light from the annular light source (3) toward the opposite camera side. It has a half mirror (4) inclined at 45 degrees leading to (2) ,
Furthermore, the half mirror (4) has an inner diameter surface (4b) of a straight cylinder and a light shielding film (5) provided on the inner diameter surface (4b),
The cone lens (2), the camera (1), and the annular light source (3) are arranged coaxially with the inspection center (C),
Illumination light from the annular light source (3) is passed through the cone lens (2) and reflected in order by the inner diameter surface (2b) of the prism surface and the outer diameter surface (2a) of the mirror surface, and the inspection just above the cone lens. Guided to the part (B) and suspended under the transport surface (10a) of the inspection object (A) sent to the inspection part (B) in a state where at least a part is suspended under the transport surface (10a). The outer peripheral side surface of the portion is illuminated with the illumination light, and an image of the entire circumference of the side surface is sequentially reflected by the outer diameter surface (2a) of the mirror surface and the inner diameter surface (2b) of the prism surface, and the camera (1 Side inspection device characterized in that it is incorporated into (1). The side inspection according to claim 1 or 2 , wherein an antireflection film (6) for preventing reflection of visible light is provided on an end face of the cone lens (2) facing the camera (1). apparatus. The side surface inspection apparatus according to any one of claims 1 to 3 , wherein a camera employing a telecentric lens is provided as the camera (1).

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