JP6574674B2 - Coating inspection device and inspection method - Google Patents

Description

  The present invention relates to an inspection technique for inspecting defects on a painted surface, and more particularly to an inspection technique suitable for inspecting a painted body surface of a vehicle such as an automobile.

  Conventionally, an inspection by an inspector has been carried out when inspecting a defect of a painted body of a painted automobile in an automobile manufacturing factory or a repair shop. In this inspection technique, a device for illuminating the painted surface of the vehicle body required for visual observation becomes a large-scale device, and it is difficult to uniformly illuminate the entire surface of the painted surface of the vehicle body. Therefore, there are problems that it is difficult to obtain a stable inspection result due to unevenness and fluctuations in illumination, and that it is difficult to obtain a certain inspection quality due to individual differences in inspection judgment among a plurality of different inspectors.

  In recent years, automation of this type of coating inspection has been studied, and Patent Document 1 proposes a technique for imaging a painted surface of an automobile with an imaging device and inspecting a coating defect from the captured image. Moreover, in patent document 2, the coating surface of the vehicle body of a motor vehicle is imaged with a camera, a digital image is acquired, the noise at the time of analyzing this digital image in an image processing apparatus is removed, and the inspection precision of a coating surface is improved. Advanced technology has been proposed.

JP 2014-81356 A JP 2010-93736 A

  The coating of automobiles employs a multi-layer coating structure, and usually the undercoat layer, intermediate coat layer, and overcoat layer are overlaid on the surface of the vehicle body substrate. Problems that occur on the surface of the coating are often mainly caused by poor coating of the topcoat layer. In particular, metallic coatings and pearl coatings, which are widely used in recent automobile coatings, have a multilayer structure consisting of an upper clear layer made of light-transmitting paint and a lower metallic layer and pearl layer. In addition, defects caused by the underlying metallic layer and pearl layer also occur. For example, in the case of metallic coating, defects such as surface irregularities, unpainted surfaces, and coating correction marks are caused by defective coating of the upper clear layer. Defects can also be the cause.

  Since the techniques of Patent Documents 1 and 2 are techniques for inspecting the coating surface, that is, the upper coating surface of the top coating layer, even if the fault of the upper coating surface is inspected, the cause of the fault is the upper layer for the reasons described above. It is difficult to determine whether it is in the lower layer or the lower layer. Therefore, conventionally, even if a coating inspection is performed, it is necessary to perform a new inspection to determine whether the cause of the failure is the upper layer or the lower layer of the topcoat layer. There is also a problem that it is difficult to effectively utilize the inspection result information as a result of the fact that the inspection result information obtained in the inspection is immediately fed back to the painting process to improve the coating.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a coating inspection technique that makes it possible to accurately inspect defects in a painted surface of a multi-layer coating structure, and to make effective use of inspection result information obtained from the inspection. .

The present invention provides an optical means for imaging a painted surface applied in two layers, a lower layer and a light-transmitting upper layer applied on the upper side, and inspects the painted surface based on the image obtained by imaging. The optical inspection unit is configured as a confocal imaging apparatus using a first laser beam having a predetermined wavelength and a second laser beam having a longer wavelength than the first laser beam. The optical means projects the first laser light and the second laser light in focus on the upper paint surface, the second laser light is set to a wavelength having a focal depth including the lower paint surface, and the control means The inspection is performed based on the first imaging output with one laser beam and the second imaging output with the second laser beam. In this case, the optical means preferably includes a common objective lens that projects the first laser light and the second laser light onto the painted surface and focuses the painted surface on the painted surface.

  In the present invention, it is preferable that the control unit is connected to the server by wire or wirelessly, and the inspection result information inspected by the control unit is shared with an external terminal connected to the server by wire or wirelessly.

  The coating inspection method of the present invention is a confocal imaging device using a first laser beam having a predetermined wavelength and a second laser beam having a wavelength longer than that of the first laser beam on a coating surface applied to at least two layers. The coating surface is inspected based on the first imaging output with the first laser light and the second imaging output with the second laser light.

  According to the present invention, the upper painted surface can be inspected from the first imaging output with the first laser light, and the lower painted surface can be inspected from the second imaging output with the second laser light. Thereby, it is possible to quickly determine whether the cause of the defect inspected on the upper layer coating surface is the upper layer coating or the lower layer coating. Further, by transmitting the inspection result information to the server, the inspection result information can be shared with an external terminal, which is effective for improving the painting technique.

Schematic sectional view of a coating film. The figure which shows the kind of defect of a coating inspection, a conceptual form, a phenomenon, and an occurrence site. The conceptual block diagram of the inspection apparatus of this invention. The block diagram of the optical system of an optical module. The schematic diagram which shows the difference in a focal depth. The figure (photograph) which shows an example of a 1st image. The figure (photograph) which shows an example of a 2nd image. The block diagram of the modification of the optical system of an optical module.

  Next, embodiments of the present invention will be described with reference to the drawings. In this embodiment, an example of inspection of automobile body coating is illustrated. As shown in FIG. 1, in an automobile body coating, an undercoat layer T1, an intermediate coat layer T2, and an overcoat layer T3 are coated in multiple layers on the surface of a base material B constituting a vehicle body panel. In the so-called metallic coating, two layers of the upper coating layer T3 are formed, which are a lower layer T31 using a glitter pigment coating and an upper layer T32 using a light-transmitting clear coating. As the paint for the glitter pigment, a paint material containing fine pieces F of alumina having light reflectivity called alumina flakes is used.

  In this metallic coating, as shown in FIG. 2, the above-described five types of coating defects occur. Each defect of “surface unevenness”, “unpainted”, and “painting correction trace” is caused by poor coating of the upper layer T32 of the topcoat layer T3. “Surface irregularities” are those in which the lower layer T31 of the topcoat layer T3 is normal, but dust and fine foreign matter have adhered to the upper surface thereof, so that convex portions are formed on the surface of the upper layer T32. “Unpainted” is a region where the lower layer T31 is normal but the oil and fat adheres to the surface thereof, and therefore a portion where the paint of the upper layer T32 does not adhere due to the water repellent action of the oil and fat occurs. “Coating correction marks” are fine scratches or the like that occur when both the lower layer T31 and the upper layer T32 are normal, but the surface of the upper layer T32 is partially corrected after coating.

  On the other hand, “brightness unevenness” and “paint-through” are caused by poor coating of the lower layer T31. “Brightness unevenness” is a result of unevenness in light reflection by the alumina flake F because the distribution of alumina flakes F contained in the lower layer T31 is biased, and unevenness in light brightness on the painted surface of the upper layer T32. . “Through coating” is a portion where the coating film thickness is thin in the lower layer T31, and the intermediate coating layer T2 is seen through in this portion, and color unevenness occurs on the coating surface of the upper layer T32.

  Any of these five types of defects can be inspected by inspecting the painted surface of the upper layer T32. However, since all the defects are detected as color unevenness or brightness unevenness on the surface of the upper layer T32, it is possible to determine accurately. difficult. In particular, since the latter two defects may cause phenomena similar to the former three defects, it is difficult to accurately inspect these differently from the others.

  As shown in FIG. 3, the inspection apparatus according to the present invention for inspecting defects in car body painting of automobiles has rails 100 laid in parallel at predetermined intervals in the inspection field, and A frame 110 having a shape is arranged so as to be movable on the rail 100 by the drive unit 120. In a region surrounded by the frame body 110, an automobile CAR that has been subjected to vehicle body coating as an object to be inspected is stopped.

  A plurality of optical units 1 are attached to the frame 110. The plurality of optical units 1 are optical means in the present invention, and are configured as an imaging device capable of scanning a required region of the painted surface of the vehicle body, imaging the painted surface, and outputting an imaging signal. . When the optical unit 1 completes imaging of a required area, the frame 110 is moved by a predetermined distance along the rail 100, and the optical unit 1 performs similar imaging again at the moving position. By repeating this, imaging of the entire surface of the vehicle body painted surface is executed.

  Each optical unit 1 is electrically connected to a control unit 2. The control unit 2 is a control means in the present invention, and is provided with an image processing unit 21, an operation unit 22, and a drive control unit 23 that operate according to a predetermined program. The image processing unit 21 performs image processing based on the imaging signal output from the optical unit 1 to generate an image of the painted surface. The arithmetic unit 22 performs image analysis on the obtained image, inspects a defect on the painted surface, and acquires inspection result information. The drive control unit 23 controls the drive unit 120 to control the movement of the frame 110.

  The control unit 2 is inputted with vehicle type information 24 such as vehicle body shape data, vehicle body type and color number of the vehicle to be inspected. In addition, an inspection process control signal 25 including a sequence control signal for executing the inspection is input. The control unit 2 controls the drive unit 23 in response to the inspection process control signal 25 while referring to the vehicle type information 24 to move the frame body 1110, and at the same time, in the image processing unit 21 and the calculation unit 22, Perform the inspection.

  A monitor 3 is connected to the control unit 2, and only the image obtained by the image processing in the image processing unit 21 or the inspection result information obtained by the computation unit 22 is displayed on the monitor 3. It is possible to do.

  Further, the control unit 2 is connected to a server 4 such as a support center conceptually shown in a wired or wireless manner, and can upload inspection result information including the above-described image obtained by inspection to the server 4. It is said that. The server 4 includes one or more external terminals 5 (in this case, external terminals 5A, 5B, and 5C) deployed in a painting department that painted the automobile, an automobile design department, a manufacturing management department, a quality management department, and the like. Are connected by wire or wirelessly, and each external terminal 5 can share the test result information loaded in the server 4 by downloading it or the like.

  The optical unit 1 is configured as a confocal microscope type imaging apparatus. FIG. 4 is a configuration diagram of an optical system of the optical unit 1, which includes a first confocal microscope MS1 and a second confocal microscope MS2 using two laser beams having different wavelengths. That is, a first laser light source 11A that emits a first laser light having a wavelength of 405 nm close to the ultraviolet region and a second laser light source 11B that emits a second laser light having a wavelength of 650 nm close to the infrared region are provided. The first and second laser beams LA and LB emitted from the laser light sources 11A and 11B are expanded to the required beam diameters by the beam expanders 12A and 12B, respectively.

  The first laser light LA from the first laser light source 11A is reflected by the first half mirror 13A and is incident on the automatic focusing unit 14. Further, the second laser light LB from the second laser light source 11B is reflected by the second half mirror 13B, and then is transmitted through the first half mirror 13A and is incident on the automatic focusing unit 14. At this time, the first laser beam LA and the second laser beam LB are integrated into one laser beam, and the integrated first laser beam LA and second laser beam LB are transmitted to the scanning projection unit 15. Entered.

  The scanning projection unit 15 includes a galvano mirror 15A whose reflection surface is deflected and controlled in an arbitrary direction, and an objective lens 15B that condenses the light reflected by the galvano mirror 15A. In the scanning projection unit 15, the laser beam is focused on the surface of the coating surface, here the coating surface of the topcoat layer T3, by the objective lens 15B, and the coating surface preset by the deflection action of the galvanometer mirror 15A. The required area is scanned.

  In order to focus the laser light on the painted surface of the upper layer T32 of the topcoat layer T3, the autofocus unit 14 receives the laser light projected on the painted surface and reflected by the painted surface, thereby The focus state is detected, and the focus position by the objective lens 15B is controlled based on the detection result. Here, control for changing the optical path length of the laser beam is performed, and specifically, control for changing the thickness of the liquid lens in the optical axis direction or its curvature is executed. As a result, the focal position of the laser beam condensed by the objective lens 15B can be changed and focused on the painted surface.

  The laser beam focused on the painted surface is reflected by the painted surface and returned to the scanning projection unit 15, and is moved backward through the scanning projection unit 15. Further, after passing through the automatic focusing unit 14 and the first half mirror 13A, the first laser beam LA is reflected by the beam splitter 16 and the second laser beam LB is transmitted. The beam splitter 16 is composed of, for example, a dichroic mirror. The second laser beam LB transmitted through the beam splitter 16 is transmitted through the second half mirror 13B and reflected by the reflection mirror 13C.

  The first laser beam LA reflected by the beam splitter 16 is condensed by the first imaging lens 17A onto the first pinhole 18A located at the focal position of the objective lens 15B, that is, the position conjugate with the painted surface position. Is done. Similarly, the second laser light LB reflected by the reflecting mirror 13C is condensed by the second imaging lens 17B on the second pinhole 18B located at a position conjugate with the focal position of the objective lens 15B. .

  A first photomultiplier 19A is disposed behind the first pinhole 18A. The first photomultiplier 19A receives the collected light and photoelectrically converts it as a first imaging signal. Similarly, a second photomultiplier 19B is disposed behind the second pinhole 18B, and an electric signal obtained by photoelectrically converting the collected light is output as a second imaging signal. The signals output from the first and second photomultipliers 19A and 19B are a first image pickup signal and a second image pickup signal, respectively, which are output to the control unit 2.

  The control unit 2 captures image signals obtained from the first confocal microscope MS1 and the second confocal microscope MS2, that is, the first image signal output from the first photomultiplier 19A and the second imagemal output from the second photomultiplier 19B. The two image pickup signals are converted into image signals by the image processing unit 21, respectively, and a first image and a second image are created based on each image signal. The calculation unit 22 inspects the coating defect by performing image analysis on the first image and the second image. Since various methods have already been proposed for the coating defect inspection method based on the image analysis, a detailed description thereof will be omitted here.

  Here, the first image obtained in the image processing unit 21 is an image of the painted surface of the upper layer T32, and the second image is an image of the painted surface of the lower layer T31. This will be described with reference to FIG. FIG. 5 is a diagram conceptually showing the focusing mechanism on the painted surface. As described above, the first laser beam LA has a shorter wavelength than the second laser beam LA. Therefore, when the first laser beam LA and the second laser beam LB are focused on the coating surface of the upper layer T32 by the objective lens 15B, the focal depth (depth of field) of the first laser beam LA is the second laser beam. It becomes shallower (shorter) than the focal depth of LB.

  That is, as shown in FIG. 5, the refractive index of the short-wavelength first laser beam lA is large and the refractive index of the long-wavelength second laser beam LB is small with respect to the same objective lens 15B. Accordingly, the focal length of the objective lens 15B is longer for the second laser beam LB than for the first laser beam LA. Therefore, when the first laser beam LA is focused on the position FA of the coating surface of the upper layer T32, the second laser beam LB is focused at a position (FB) below (inward) the coating surface.

Furthermore, since the aperture angle of the first laser beam LA is larger than the aperture angle of the second laser beam LB from the above, when the resolution limit of the first laser beam LA and the second laser beam LB is set to the same δ, The focal depth DB of the second laser light LB is deeper (longer) than the focal depth DA of the first laser light LA.

  Therefore, the coating surface of the upper layer T32 is included in the focal depth DA of the first laser beam LA, but the coating surface of the lower layer T31 is not included. On the other hand, the coating depths of both the upper layer T32 and the lower layer T31 are included in the focal depth DB of the second laser beam LB. As a result, the first photomultiplier 19A that has received the first laser light LA can image the painted surface of the upper layer T32 within the focal depth DA. On the other hand, in the second photomultiplier 19B that has received the second laser beam LB, the painted surface of the upper layer T32 and the painted surface of the lower layer T31 within the focal depth DB can be imaged.

  In other words, the first confocal microscope MS1 obtains a first image obtained by imaging the painted surface of the upper layer T32, and the second confocal microscope MS2 obtains a second image obtained by integrally imaging the painted surfaces of the upper layer T32 and the lower layer T31. Is obtained. However, while the upper layer T32 is a light-transmitting clear paint coating layer, the lower layer T31 is a layer having high light reflection characteristics containing alumina flakes, so it is compared with the imaging signal obtained from the painted surface of the upper layer T32. Thus, the signal level of the imaging signal obtained from the painted surface of the lower layer T31 becomes relatively high, and the second image is substantially an image based on the imaging signal of the painted surface of the lower layer T31.

  Thus, the first image of the painted surface of the upper layer T32 is obtained from the first confocal microscope, and the second image of the painted surface of the lower layer T31 is obtained from the second confocal microscope. The arithmetic unit 22 of the control unit 1 performs image analysis on the first and second images, thereby inspecting the coating surface of the upper layer T32 from the first image and coating the lower layer T31 from the second image. Can check for surface defects.

  For example, from the first image of the painted surface of the upper layer T32 obtained by the first confocal microscope MS1, each defect of “surface irregularities”, “unpainted”, and “painting correction traces” shown in FIG. 2 can be inspected. . In addition, from this first image, there are cases where each defect of “brightness unevenness” and “paint-through” can be inspected and cannot be inspected. However, even if inspection is possible, these “brightness unevenness” and “paint-through” appear as images that are difficult to distinguish from “surface irregularities”, “unpainted”, and “paint correction traces”, so it is not possible to identify defects. difficult.

  Therefore, the control unit 2 performs image analysis on the calculation unit 22 in addition to the first image and also with the second image, and inspects the coating surface of the lower layer T31 with the second image. When a defect on the painted surface of the lower layer T31 cannot be inspected from the second image, the defect inspected in the first image is determined to be a defect on the painted surface of the upper layer T32, and becomes one of the former three defects.

  On the other hand, when a defect is inspected from both the first image and the second image, there is a defect on the painted surface of the lower layer T31, which is one of the latter two defects. The defect is not inspected from the first image, but there are few forms where the defect is inspected from the second image, but the defect on the painted surface of the lower layer T31 is minor and the defect cannot be inspected from the painted surface of the upper layer T32 Therefore, such a defect can be inspected as a defect on the painted surface of the lower layer T31.

  6A and 6B are examples of the first image and the second image. FIG. 6A is a first image obtained from the painted surface of the upper layer T32, and FIG. 6B is a second image obtained from the painted surface of the lower layer T31. It can be inspected that the black spot portion occurring in the first image in FIG. 6A is a defect on the painted surface of the upper layer T32. It can be inspected that the portion where the distribution of white spots occurring in the second image in FIG. 6B is uneven is a defect on the painted surface of the lower layer T31. As described above, by referring to the first image and the second image, it is possible to inspect the defects of the upper layer T32 and the lower layer T31 with high accuracy.

  In the inspection apparatus shown in FIG. 3, the control unit 2 performs the above inspection while the drive control unit 23 controls the drive unit 120 based on the input vehicle type information 24 and changes the moving position of the frame 110. By doing this, the first image and the second image can be acquired for all the painted surfaces of the car body painting of the automobile, and the inspection of all the painted surfaces of the car body painting can be performed. The obtained first image and second image may be displayed on the monitor 3 as described above, and in that case, the inspected defective portion may be superimposed on the displayed image and displayed. Good.

  Further, the control unit 2 uploads inspection result information including the image of the inspected painted surface to the server 4. Thereby, in each external terminal 5 connected to the server 4, inspection result information can be downloaded at any time, and it is possible to promptly check for defects of the inspected car body painted surface. Therefore, for example, it is possible to immediately take countermeasures for the confirmed defects in the painting department and prevent the occurrence of the defects thereafter. Alternatively, the paint correction department can prepare for correction before the car is transferred.

  The optical unit 1 according to the present invention is not limited to the configuration of the optical system shown in FIG. For example, as shown in FIG. 7, the first laser light LA from the first laser light source 11A and the second laser light LB from the second laser light source 11B are incident on one beam expander 12, where both lasers The light beams may be expanded after the light beams LA and LB are integrated into one light beam. Other configurations are the same as those in FIG. By doing in this way, it can comprise by one beam expander 12, and since the half mirror 13B can be abbreviate | omitted, the structure of an optical unit can be simplified.

  In the embodiment, the wavelength of the first laser beam is set to 405 nm and the wavelength of the second laser beam is set to 650 nm. However, the wavelength is not limited to these wavelengths. However, for the second laser light on the long wavelength side, it is necessary to set the depth of focus when focused on the surface of the upper layer to a wavelength that can include the lower painted surface.

  In the embodiment, an example of metallic coating has been described, but the lower layer may not be particularly coated with a bright pigment, and may be a general chromatic color coating as long as it can be distinguished from the upper layer by a color difference. Also good. Further, the upper layer is not necessarily a colorless and transparent paint as long as it is a light-transmitting paint.

  The present invention is not limited to automobile body painting, and can be applied to various coating inspections such as painting of home appliances.

1 Optical unit (optical means)
2 Control unit (control means)
3 monitor 4 server 5 external terminal 11A first laser light source 11B second laser light source 14 auto focus unit 15 scanning projection unit 15A galvanometer mirror 15B objective lenses 17A and 17B imaging lenses 18A and 18B pinholes 19A and 19B photomal 21 image processing Unit 22 Calculation unit 23 Drive control unit 100 Rail 110 Frame body 120 Drive unit LA First laser beam LB Second laser beam T1 Undercoat layer T2 Middle coat layer T3 Top coat layer T31 Lower layer (light luminance paint)
T32 upper layer (clear paint)
F Alumina flake

Claims (5)

Optical means for imaging a painted surface applied to two layers with a lower layer and a light-transmitting upper layer applied thereon, and a control means for inspecting the painted surface based on the image obtained by imaging The optical inspection unit is configured as a confocal imaging device using a first laser beam having a predetermined wavelength and a second laser beam having a wavelength longer than that of the first laser beam , The optical means projects the first laser beam and the second laser beam in a focused state on the upper layer coating surface, and the second laser beam is set to a wavelength having a depth of focus including the lower layer coating surface, The coating inspection apparatus, wherein the control means performs an inspection based on a first imaging output with the first laser light and a second imaging output with the second laser light.   The coating inspection apparatus according to claim 1, wherein the optical unit includes a common objective lens that projects the first laser light and the second laser light onto the coating surface. 3. The paint inspection apparatus according to claim 1, wherein the paint surface is a car body paint surface of an automobile, and the optical means is configured to scan and image a predetermined region of the car body paint surface by the control means. Wherein the control means is wired or wirelessly connected to the server, according to any one of 3 claims 1 shared between the test result information examined in the control unit and the external terminal is wired or wirelessly connected to the server Painting inspection equipment. A first laser beam having a predetermined wavelength and a second laser having a wavelength longer than that of the first laser beam are applied to a coating surface applied in two layers, a lower layer and an upper layer having optical transparency applied on the lower layer. Imaging with a confocal imaging device using laser light, and both coating of the upper layer and the lower layer based on the first imaging output with the first laser light and the second imaging output with the second laser light A coating inspection method for inspecting a surface, wherein the first laser beam and the second laser beam are projected and focused on the upper layer coating surface by a common objective lens, and the first laser beam is applied to the lower layer. A coating inspection method using light having a wavelength of a focal depth including a painted surface .