JPH04204148A - Surface-defect inspecting apparatus - Google Patents

Abstract

PURPOSE:To make it possible to ensure the detection of a defect regardless of the kind of the surface defect by inputting an image from an image inputting means, and judging the presence or absence of abnormality on the surface to be inspected of a work. CONSTITUTION:The surface of a piston 1 which is a work is cleaned by a cleaning machine 2. Then, the piston 1 waits at the specified position of a conveying means 3. The piston 1 is mounted on a rotary stage 6 as a driving means for an inspecting stage 5 by a loader 4. During the period when the work is rotated by one rotation with the rotary, stage 6, the surface-defect inspection of the surface to be inspected of the piston 1 is performed a plurality of cameras 7 provided around the rotary stage 6. When the result of the inspection is OK, the piston 1 is sent into a rust preventing oil tank 9 by a pusher 8. When the result is NG, the piston 1 is sent into a work stock area 10 by the distributing pusher 8. The piston of OK is contained in a pallet 12 by a palletizing robot 11. The piston of NG is visually inspected by a worker on a working table 13. Then, the piston is put into a rust preventing oil tank 14 and contained in a pallet 15.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a surface defect inspection device for inspecting defects on the surface of a workpiece after it has been processed by, for example, a machine tool.

(Prior art) Generally, manufacturing and processing lines in production plants, etc. are equipped with an inspection process to inspect the quality of processed products, or in today's highly automated world, visual inspection by workers is replaced by an inspection process. The quality of products is now being inspected using engineering equipment such as cameras.

Among these quality inspections, there is surface defect inspection that checks whether there are defects such as scratches on the surface of the processed product.For example, surface defect inspection of automobile camshafts
The surface to be inspected of the camshaft is always irradiated with light from a specific direction, the light from this surface to be inspected is input by a camera, this input light is received by a line sensor installed inside the camera, and the line sensor By processing the photoelectrically converted voltage value by a video signal processing circuit, the surface to be inspected is inspected for defects.

In this inspection, for example, if there is a defect on the surface to be inspected, light will be diffusely reflected at the defective part, so the amount of light received by each part of the line sensor will be uneven, and the output from this line sensor will be uneven. Since the voltage value is also non-uniform, this voltage value is processed by a video signal processing circuit,
By detecting this non-uniformity of voltage values, it is possible to detect the presence or absence of defects.

(Problem to be solved by the invention) However, in such conventional surface defect inspection equipment, the illumination that irradiates the inspected surface with light is fixed, and a specific It was designed to emit light from all directions. In other words, because the relative positions of the camera and the light irradiation positions with respect to the surface to be inspected are always constant, there are multiple spots on the surface to be inspected that cannot be inspected under the same lighting conditions formed by the camera and lighting. When there are defects, there is a problem in that each defect cannot be inspected under optimal illumination conditions.

In other words, if the relative position of the camera and the light irradiation position with respect to the surface to be inspected is always constant, narrow flaws such as scratches, for example, are easy to detect because the degree of diffuse reflection increases, but Relatively wide scratches may be difficult to detect because the degree of diffuse reflection is small, and the opposite may occur depending on the lighting conditions.As shown above, depending on the type of surface defect, In the conventional method, which has undetectable elements,
This results in a lack of reliability as a surface defect inspection.

The present invention has been made in view of these conventional problems, and it is possible to set the optimal illumination conditions for detecting each type of surface defect depending on the various types of surface defects that the workpiece has. To provide a surface defect inspection device in which a defect is reliably detected regardless of the type of surface defect by arranging a plurality of cameras and illumination around the workpiece.

(Means for Solving the Problems) The present invention for achieving the above object includes: an illumination device that irradiates light from an arbitrary direction onto a surface to be inspected of a work; and an image of the surface to be inspected that is irradiated with the illumination device. a first image input means for inputting an image of the inspected surface from the direction of the light reflected specularly from the inspected surface; and a first image input means inputting an image of the inspected surface from the direction of the light irradiated by the illumination and diffusely reflected from the inspected surface a second image input means; a drive means for moving the workpiece so that the image of the surface to be inspected is input to the image input means; a drive means for inputting the image from the image input means; The device is characterized by having a determining means for determining whether or not there is an abnormality in the device.

(Function) With this configuration, the surface to be inspected of the workpiece is illuminated with light from an arbitrary direction, and the first image means detects the surface to be inspected of the workpiece from the direction in which this light is specularly reflected by the surface to be inspected of the workpiece. The second image means inputs an image of the surface to be inspected of the workpiece from the direction in which this light is diffusely reflected on the surface to be inspected of the workpiece. surface defect inspection will be performed. Then, when the workpiece is rotated once by the drive means, a plurality of images of the inspected surface under different lighting conditions are inputted to the determination means. In this way, each camera can inspect the inspected surface under different lighting conditions, making it possible to detect any type of defect.
Improved reliability of surface defect detection.

(Example) Below, a surface defect inspection apparatus according to the present invention will be explained in detail based on the drawings.

FIG. 1 shows an example in which the surface defect inspection device of the present invention is applied to a processing line.

After the surface of the piston 1, which is a workpiece, is cleaned by a washer 2, it waits at a predetermined position in a transport device 3, and is placed by a loader 4 on a rotary table 6 serving as a driving means for an inspection table 5. Then, while the workpiece is rotated once by the rotary table 6, a surface defect inspection of the surface to be inspected of the piston 1 is performed by a plurality of cameras 7 provided around the rotary table 6, and the inspection results are If OK, the piston 1 is distributed to the antirust oil tank 9 by the pusher 8, and if not, the piston 1 is distributed to the works dock area 10 by the pusher 8.

Then, the OK items are stored on a pallet 12 by the palletizing robot 11, and the NG items are visually inspected by an operator on the workbench 13, then placed in a rust preventive oil tank 14, and stored on a pallet 15.

FIG. 2 shows a schematic configuration diagram of an inspection stage equipped with a surface defect inspection apparatus according to the present invention.

As shown in the figure, this inspection stage is equipped with a rotating table 6 that supports and rotates the piston 1.
This rotary table 6 is adapted to be rotated by a motor 20. In addition, this rotary table 6 also includes an air chuck 2.
1 is provided, and the piston 1 is supported by this air chuck 21.

As shown in the figure, around this rotary table 6, there are two cameras 7 that input an image of the surface S to be inspected of the piston 1 illuminated horizontally by a lamp 22 as an illumination.
a and 7b are respectively arranged, and this lamp 22 and each camera 7a.

The illumination conditions for the surface S to be inspected 7b are set to be optimal for detecting various surface defects that the surface S to be inspected has.

The details of this setting are as shown in Figure 3 (A).
2 is provided at a position to irradiate light from the horizontal direction to the surface S to be inspected of the piston 1, and a camera 7a called a specular reflection sensor is irradiated from this lamp 22 to the surface S to be inspected.
The camera 7b, which is called a diffused reflection sensor, is placed in a position to receive the diffusely reflected light emitted from the lamp 22 and reflected from the surface S to be inspected. ing. Note that the light from this lamp 22 is spot light.

The lamp 22 and camera 7a are placed in such a position.

7b, if there are deep and small defects a such as scratches on the inspection surface S, as shown in the figure, when light is irradiated onto the parts of these defects a, diffuse reflection will occur at these parts. Therefore, the partial amount of light input to the camera 7a, which is a specular reflection sensor, is reduced. In this case, when the partial amount of light received during one scan by the camera 7a is developed in two dimensions, it can be schematically shown in FIG. The amount of light is decreasing. Therefore, under such illumination conditions, it becomes possible to easily detect deep and small defects a such as scratches.

In addition, if there are shallow and wide-ranging defects such as surface grinding on the surface S to be inspected, as shown in the figure, when light is irradiated onto these defective areas, diffuse reflection may occur at these areas. Therefore, the partial amount of light input to the camera 7b, which is a diffuse reflection sensor, increases compared to the case where there is no defect.

In this case, the partial amount of light received by the camera 7b during one scan can be schematically shown by inverting it in FIG. 3(C). The amount of light is increasing. Therefore, under such illumination conditions, shallow and wide-ranging defects such as flat spots can be easily detected.

FIG. 4 shows a block diagram of a control system in a surface defect inspection apparatus according to the present invention.

As shown in the figure, the input/output device 3o provided in the control device 40 as a judgment means includes a camera 7a as a first image input means, a camera 7b as a second image input means, and a workpiece. Motor 20 that rotates piston 1
．． An encoder 31 that detects the rotation angle and rotation speed of this motor 2o, a lamp 22 that irradiates light onto the surface to be inspected of the piston 1, and a display device 32 that displays the inspection results are connected from the outside to these devices or to these devices. Signals from the equipment are sent and received via this input/output device 3o.

The input/output device 3o also includes a camera 7a.

An image processing unit 33 that processes the image signal of 7b, and a motor 2
0. A device control section 34 that controls the operation of the lamp 22 and the display device 32 is connected, and the image processing section 33 and the device control section 34 detect scratches on the surface to be inspected of the piston 1 based on signals from the image processing section 33. A scratch detection section 35 is connected to detect the presence or absence of scratches. Then, the device control section 34
The rotational speed of the motor 20, the operation of the display device 32, etc. are controlled based on signals from the image processing section 33 and the flaw detection section 35.

The surface defect inspection device of the present invention configured as described above has the following features:
The surface defect inspection of the surface to be inspected is performed by operating as shown in the operation flowchart shown in FIG. Below, we will explain this behavior in the second example.
This will be explained with reference to FIGS.

Step 1 First, when the start of work is commanded and the program starts, the control device 40 shown in FIG.
Initializes the operating status of all equipment connected to the system and prepares for inspection processing. Then, when the piston 1 is supported on the rotary table 6 by the air chuck 21 as shown in FIG. Rotate 1.

Step 2 As shown in FIG. 3, each of the cameras 7a and 7b receives specularly reflected light and diffusely reflected light from a predetermined range on the surface S to be inspected by the lamp 22, and receives the specularly reflected light and diffusely reflected light from a predetermined range on the surface S to be inspected. Photoelectric conversion is performed by an element such as a CCD, and the converted signal is output to the input/output section 30.

Step 3 The image processing unit 33 stores the respective signals from the cameras 7a and 7b output in Step 2 as image data. When this storage process is completed, the image processing section 33 outputs a signal to the device control section 34, and the device control section 34 rotates the motor 20 via the input/output device 30. As a result, each camera 7a s 7b receives specularly reflected light and diffusely reflected light in different areas.

Step 4 Based on the signal from the encoder 31, the device control unit 34 uses the cameras 7a and 7b to detect the inspection surface S of the piston 1.
Determine whether image data for all parts of the image have been captured. In other words, it is determined whether the piston 1 has made one revolution from its original position.

As a result of this judgment, if the image data of all parts of the surface to be inspected S has not been taken, the processes from step 2 to step 4 are repeated, and when the image data of all parts of the surface to be inspected S has been taken, the device The control unit 34 outputs a termination signal to the image processing unit 33 and also outputs a termination signal to the motor 2 via the input/output device 30.
Stop the rotation of 0 and proceed to the next step.

Step 5 The image processing section 33 processes all the image data stored in the processing of steps 2 and 3, and outputs the data to the flaw detection section 35.

The processing of the image data in the image processing unit 33 is as shown in the image processing algorithm in FIG. logic 1 to, or
Binarization processing is performed by a positive logic operation that assigns a logical O when the value is smaller (darker) than a predetermined threshold. On the other hand, the image data in which the signal from the camera 7b is stored is a logic 0 when the voltage value is larger (brighter) than a predetermined threshold value, and a logic 0 when the voltage value is smaller than a predetermined threshold value (ILS).
The binarization process is performed by a negative logic operation that assigns a logic 1 in the case. Further, these binary signals are subjected to AND processing in the image processing section 33, and the data is outputted to the kiss detection section 35.

Step 6 The scratch detection unit 35 determines the presence or absence of scratches based on this data, and outputs the result to the device control unit 34. Then, the device control unit 34 operates the display device 32 via the input/output device 30, and causes the display device 32 to display the test results.

In this way, by arranging a specular reflection sensor and a diffuse reflection sensor corresponding to one lamp, a plurality of illumination conditions can be set for the surface to be inspected S, and the surface to be inspected can be inspected under each of the set illumination conditions. When an image of the inspection surface S is inputted by a camera and this image is processed by the control device 40 to inspect various surface defects, the camera views the same inspection surface S under a plurality of illumination conditions. Since it becomes easier to detect various defects, the reliability of surface defect inspection is improved.

Although a piston is illustrated as an example of the workpiece in this embodiment, the surface defect inspection apparatus of the present invention is not limited to this, but any workpiece having a two-dimensional or three-dimensional plane can be used. It is possible to apply

In addition, in this example, the illumination condition is illustrated in which two cameras are arranged corresponding to the lamps that illuminate the surface to be inspected from the horizontal direction, but the illumination condition is not limited to this, It is also possible to arrange a lamp at the irradiation position, and two or more cameras may be arranged. Moreover,
It is also possible to arrange a camera corresponding to a lamp that irradiates the surface to be inspected from the horizontal direction, and to arrange a camera corresponding to a lamp that irradiates the surface to be inspected from, for example, an obliquely upward direction.

Furthermore, although the image processing is performed after storing all the image data on the surface to be inspected of the workpiece, it is of course possible to process the image data obtained by a camera in real time. .

(Effects of the Invention) As is clear from the above explanation, according to the present invention, the optimal illumination conditions are set for each type of surface defect detection according to the various types of surface defects that the workpiece has. Lighting and a plurality of image input means are arranged around the workpiece, the workpiece is moved by the drive means, and surface defects are detected by the judgment means, so that the image input means can detect the same surface S to be inspected. Since it can be viewed under multiple lighting conditions, it is possible to reliably detect surface defects regardless of their type.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing an example of a case where the surface defect inspection device according to the present invention is applied to a processing line, and FIG. 2 is a schematic configuration diagram of an inspection stage equipped with the surface defect inspection device according to the present invention. 3(A) is a diagram showing the setting status of the lamp and camera on the inspection stage shown in FIG. 2, FIG. 3(B) is a schematic diagram showing the amount of light received by the camera that receives specularly reflected light, FIG. 3(C) is a schematic diagram showing the amount of light received by a camera that receives diffusely reflected light; FIG. 4 is a block diagram of the control system in the surface defect inspection apparatus according to the present invention; FIG. The operation flowchart of the control system shown in FIG. 6 is the image processing algorithm of step 5 shown in FIG. DESCRIPTION OF SYMBOLS 1... Piston (workpiece), 6... Turntable (driving means), 7a... Camera (first image input means), 7b... Camera (second image input means), 22... lamp (lighting)
, 40...control device (determination means), S...surface to be inspected. Figure 2 Figure 4 Figure 6 7b 21811 Procedural Amendment February 7, 1991 1990 Patent Application No. 335.462 Surface Defect Inspection Device Yutaka Iriki Spontaneous Amendment

Claims (1)

[Claims] An illumination device that irradiates light from any direction onto a surface to be inspected of a workpiece, and an image of the surface to be inspected from the direction of light irradiated by the illumination and specularly reflected from the surface to be inspected. a first image input means for inputting an image of the surface to be inspected; a second image input means for inputting an image of the surface to be inspected from a direction of light irradiated by the illumination and diffusely reflected from the surface to be inspected; The method further includes: a drive means for moving the workpiece so that an image of the inspection surface is input; and a determination means for inputting the image from the image input means and determining the presence or absence of an abnormality in the surface to be inspected of the workpiece. Features of surface defect inspection equipment.