JPH01201140A - Surface flaw inspection device - Google Patents

Abstract

PURPOSE:To improve the accuracy of surface flaw inspection by making reflected light from a curved rotary body incident on a camera with the nearly uniform quantity of light entirely in the direction of the center axis of the rotary body. CONSTITUTION:The bent part of the surface of the curved rotary body 1 consists of three parts L1-L3 approximated to straight lines in a direction parallel to the center O of rotation. Then three light sources 11-13 are arranged corresponding to those three parts and installed at specific angles so that their light beams are reflected by the respective parts L1-L3 and light incident on the linear camera 3 becomes a regular reflecting surface. Consequently, the output of the sensor in the camera 3 is entirely uniform corresponding to the position along the center axis O, so when there is a flaw such as a recessed part and a scratch in the surface, it appears as a dark part in the reflected light from the part.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention uses a curved rotating body with a curved surface, such as an automobile part, as an object to be inspected, and a surface for inspecting surface defects such as scratches on the surface. Related to defect inspection equipment.

(Prior art) Among various parts such as automobile parts, there are curved rotating bodies with curved surfaces, and after cutting or grinding the surfaces of these parts, it is necessary to process the surfaces to a predetermined accuracy. A surface defect inspection device is used to automatically inspect whether defects such as scratches have occurred on the surface.

FIG. 3 is a diagram showing a surface defect inspection apparatus conventionally used for inspecting surface defects of a curved rotating body as described above. A curved rotating body 1, which is rotatable by a rotating shaft (not shown), is irradiated with planar light from one light source 2 at a predetermined angle. A one-dimensional camera 3 for receiving the light reflected by the curved rotating body 1 is arranged facing the curved rotating body 1. Inside the -dimensional camera 3, a photoelectric sensor made of a CCD or the like, that is, a line sensor is incorporated.

Since the surface of the rotating body 1 is circular in the rotation direction, the reflected light incident on the -dimensional camera 3 becomes linear at the part of the curved rotating body 1 surface where the light from the light source 1 touches. incident.

(Problems to be Solved by the Invention) In such a conventional surface defect inspection device, the surface of the rotating body 1 is curved in the direction parallel to the rotation center axis O of the rotating body 1, and the Regarding the light that enters the one-dimensional camera 3 in the form of a shape, the amount of reflected light decreases as the portion deviates from the optical axis in a portion that is largely inclined with respect to the rotation center axis O. FIG. 3 shows the relationship between the sensor output corresponding to the amount of reflected light on the object to be inspected having the illustrated shape and the axial position of the rotating body 1, which is the object to be inspected.

In order to inspect the defect state of the surface of the object to be inspected 1 using the sensor output signal as shown in the figure, the surface of the object to be inspected 1 must be in an appropriate state from the image waveform signal obtained from the sensor output signal. A threshold level, that is, a threshold value, is determined as a reference for determining whether or not the image signal is generated.If the image signal waveform is higher than this threshold level, it is determined that the surface is in an appropriate state. Conversely, if it is low, it is determined that a surface defect such as a scratch exists in that area. These determinations are made automatically, and the rotational position of the inspection object 1 and the position on the central axis 0 are stored in the storage medium.

However, in the conventional surface defect inspection apparatus as described above, the output signal from the sensor itself may vary depending on the position in the direction parallel to the central axis O depending on the curved state of the inspected object 1. The sensor output will change accordingly. For this reason, in areas where the amount of reflected light is small, there is a problem in that the contrast between defects such as scratches on the surface and normal areas is reduced, resulting in a decrease in surface defect detection accuracy.

The present invention has been made in view of the above-mentioned problems of the prior art, and the present invention has been made in view of the above-mentioned problems of the prior art. The purpose is to improve surface defect inspection accuracy by making the light incident on the original camera.

(Means for Solving the Problems) The present invention to achieve the above object irradiates light from a light source to a curved rotating body having a curved surface on the surface, and reflects the light linearly through the curved rotating body. In the surface defect inspection apparatus, a one-dimensional camera that receives reflected light that is reflected from the curved body is arranged opposite to the curved body of rotation to inspect the surface of the curved body of rotation, and the surface of the curved body of rotation is set as the center of rotation. The curved rotating body is divided into a plurality of sections in parallel directions, each of which is approximated to a straight line, and a light source that irradiates light at a predetermined angle to each of the sections is arranged adjacent to the curved rotating body. This is a surface defect inspection device.

(Function) The light irradiated from the light source to the curved rotating body, which is the object to be inspected, is
A predetermined amount of light is incident at a predetermined angle on a plurality of sections that are approximately straight-lined on the surface of the curved rotating body, and the light that enters the one-dimensional camera from each section is connected to the object to be inspected. The same amount of light is incident on the sensor of the one-dimensional camera throughout the reflected portion. As a result, the sensor can clearly distinguish between cases where there is a defect on the surface and cases where there is no defect, and the surface defect detection accuracy is improved.

(Example) Hereinafter, the present invention will be described in detail based on an example of the present invention illustrated in the drawings.

FIG. 1 is a diagram showing a surface defect inspection apparatus according to a first embodiment of the present invention, and in this figure, parts common to those in the conventional apparatus are given the same reference numerals.

A curved rotating body 1 having a curved surface is rotatable about a shaft (not shown), and a one-dimensional camera 3 is arranged opposite to this curved rotating body 1.

The structure of this -dimensional camera 3 is similar to that described above, and a line sensor made of a CCD element is incorporated inside.

In the case of a curved rotating body 1 having the shape shown in the figure, this rotating body 1
The surface of is divided into three parts fS by approximating its curved parts to almost straight lines in the direction parallel to the center of rotation O, 1 to L3.
It is divided into In order to irradiate these portions with light separately, three light sources 11 to 1-3 corresponding to the three divided portions are arranged facing the curved rotating body 1, which is the object to be inspected. Each of the light sources 11 to 13 is installed at a predetermined angle so that the light reflected by the three portions L1 to L3 and incident on the one-dimensional camera 3 becomes a specular reflection surface.

Therefore, in the surface defect inspection apparatus of the present invention as described above, the output of the sensor obtained by the reflected light incident on the sensor in the -dimensional camera 3 is as shown in FIG. It becomes uniform as a whole depending on the position in the direction along the central axis ◯ of 1. As a result, if there is a defect such as a crack or scratch on the surface, the reflected light from that area will appear as a clearly dark area compared to other areas, and the sensor will reliably detect the defective area. will be done. However, since the incident angles, that is, the regular reflectances are different in each of the plurality of sections, the light sources 11 to 13
It is necessary to change the amount of light irradiated each time so that the sensor output becomes uniform throughout as shown in FIG.

Note that depending on the shape of the curved rotating body 1 that is the object to be inspected,
It may be divided into one or more parts.

FIG. 2 is a diagram showing a surface defect inspection apparatus according to a second embodiment of the present invention, in which one light source 14 is used.
Between this light source and the curved rotating body 1, there are three reflecting mirrors 15 to 15 with integrated filters in order to irradiate light at different predetermined angles to each of the three divided parts.
17 are arranged. The filter is a curved rotating body 1
This is to adjust the direction of light directed toward the light source 14 at a predetermined luminous intensity and at a predetermined angle to each portion L1 to L3.
It will be illuminated by light from In this case, light sources that irradiate the object to be inspected at different angles are formed in three portions L1 to L3, including one light source and three reflecting mirrors 15 to 17.

(Effects of the Invention) As described above, according to the present invention, the surface of the curved rotating body is divided into a plurality of portions that are each approximated to a straight line in a direction parallel to the center of rotation, and Since a light source that irradiates light onto these objects at a predetermined angle is placed adjacent to the curved rotating body, the light reflected from the curved rotating body having a curved surface has a constant amount of light as a whole and is reflected within the one-dimensional camera. If there is a surface defect such as a scratch on the surface of the curved rotating body, that area will clearly appear as a dark area within the sensor, greatly improving the accuracy of surface defect inspection. I decided to do it.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing a schematic structure of a surface defect inspection apparatus according to an embodiment of the present invention, and FIG. 2 is a perspective view showing a schematic structure of a surface defect inspection apparatus according to another embodiment of the present invention. FIG. 3 is a perspective view showing the schematic structure of a conventional surface defect inspection device. 1... Curved rotating body, 3...-dimensional camera, 11-1
-4...Light source. Patent applicant Nissan Motor Co., Ltd. agent Patent attorney 8 1) Mikio (and 1 other person) Figure 1

Claims (1)

[Claims] A one-dimensional camera that irradiates light from a light source to a curved rotating body having a curved surface and receives reflected light linearly reflected through the curved rotating body is arranged opposite to the curved rotating body. In the surface defect inspection device for inspecting the surface of the curved rotating body, the surface of the curved rotating body is divided into a plurality of portions that are each approximated to a straight line in a direction parallel to the center of rotation, and each of the portions is A surface defect inspection device comprising: a light source arranged adjacent to the curved rotating body to irradiate light at a predetermined angle to correspond to the curved rotating body.