JPH05149894A - Flaw detector - Google Patents

Abstract

PURPOSE:To obtain a flaw detection device capable of exact defect detection even for an object moving at high speed. CONSTITUTION:A flaw detector has light casting means 1 to 3 radiate light on the surface of an object S with round or annular side cross section and a light reception means 4 to receive light reflected on the surface of the inspected body S and detects defects in the object based on the output of the light reception means 4. And a multitude of light casting means to cast light for each of a plurality of angular regions of the entire angular region of the object is provided. With the plurality of light casting means, while angular region of the object surface is lightened.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flaw detection apparatus for detecting defects on the surface of an object to be inspected, and more particularly to a flaw detection apparatus using laser light.

[0002]

2. Description of the Related Art Conventionally, there has been a flaw detection device for detecting defects on the surface of a round bar by irradiating the surface of the round bar with laser light and detecting the reflected light while moving the round bar in the axial direction. Being developed.

In such a flaw detector, in order to detect defects on the surface of the round bar, it is necessary to irradiate the laser beam over the entire angular range of the surface of the round bar, that is, the entire circumference. Therefore, conventionally, the laser light emitted from the laser light source is scanned using a driving mirror to irradiate the laser light on the entire circumference of the surface of the round bar (Japanese Patent Publication No. 63-64849).
Japanese Patent Publication, Japanese Patent Publication No. 64-657, Japanese Patent Laid-Open No. 53-27.
087).

[0004]

However, in the conventional flaw detector for scanning the laser beam using the driving mirror, the round bar moves in the axial direction. It will proceed in a spiral. Therefore, if the moving speed of the round bar increases, accurate detection cannot be performed. Generally, such a conventional flaw detection device is arranged on a round bar production line, and therefore cannot be applied to a line having a high production speed.

It is an object of the present invention to provide a flaw detection apparatus capable of accurately detecting a defect even if the moving speed of an object to be inspected is high.

[0006]

A flaw detection apparatus according to the present invention is provided with a light projecting means for irradiating the surface of an object to be inspected, which has a circular or circular cross section, with light, and to receive reflected light from the surface of the object to be inspected. In the flaw detection device for detecting a defect of the object to be inspected based on the output of the light receiving means, a light is output for each angular range in which the entire angular range of the surface of the inspected object is divided into a plurality of parts. A plurality of light projecting means for irradiating are provided, and the plurality of light projecting means irradiate the entire angular range of the surface of the object to be inspected.

Each of the light projecting means comprises, for example, a laser light source and an optical system for converting a light beam emitted from the laser light source into an elongated light beam which spreads in a corresponding angular range on the surface of the object to be inspected. You may comprise. In addition, each of the light projecting means includes a laser light source, a light adjusting optical fiber to which light emitted from the laser light source enters from an input end, and a light beam emitted from the emitting end of the light adjusting optical fiber to the above-mentioned It may be configured with an optical system that converts the light beam into an elongated light beam that spreads over a corresponding angle range on the surface of the inspection object.

A cylindrical lens, for example, is used as the optical system. Further, the optical system is composed of a cylindrical lens, and a light adjusting slit member arranged in front of the cylindrical lens and for removing a peripheral portion of a light beam that has passed through the cylindrical lens. You may. The angle of irradiation of the light emitted from the optical system onto the surface of the object to be inspected is rotatably attached to the surface of the object to be inspected, and the angle of irradiation of the light emitted from the optical system onto the surface of the object to be inspected. Is preferably adjusted.

It is preferable that the light receiving means includes a donut-shaped light collecting member for collecting the reflected light from the surface of the object to be inspected. Further, in order to effectively send the light incident on the light collecting member to the photoelectric conversion means such as a photomultiplier tube, the light reflecting film has a light reflecting surface inside the light collecting portion on the surface of the light collecting member. It is preferably formed so as to be oriented. Further, it is preferable to form irregularities on a portion of the surface of the light-collecting member facing the light incident portion.

The light condensing member is movably attached in the axial direction of the object to be inspected, and a position where the light condensing member can receive the specularly reflected light from the object to be inspected and a position from the object to be inspected. It is preferable that the diffused light can be switched to a position where the light collecting member can receive the light.

[0011]

The whole angular range of the object to be inspected, which has a circular or circular cross section, is divided into a plurality of parts, and light is emitted by different light projecting means for each of the divided angular ranges.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the present invention is applied to a flaw detection device for detecting defects on the surface of a linear body having a circular cross section will be described below with reference to the drawings.

FIG. 1 shows the basic structure of a flaw detector.

A flaw detector is arranged at a predetermined position where the finished product is sent from the production line of the linear body S.
The moving direction of the linear body S is indicated by an arrow A. Hereinafter, in this specification, the forward and backward directions are based on the feeding direction of the linear body S.

An inspection position P is set at a predetermined position on the conveyance path L of the linear body S. Behind the inspection position P, three light projecting units 1, 2, and 3 are arranged around the linear body S.
As shown in FIG. 2, these light projecting units 1, 2, and 3 are arranged in a circumferential direction on a concentric circle centered on the central axis L of the linear body S.
They are arranged at intervals of 0 degree. Each floodlight 1,
Laser light is sent from the same laser light source 8 (see FIG. 4) to the light sources 2 and 3 through a light adjusting optical fiber 9 (see FIG. 4). As the light regulating optical fiber 9, either a multimode optical fiber or a single mode optical fiber may be used, but it is preferable to use a single mode optical fiber. As the laser light source 8, for example, He-
A Ne laser generator is used.

At the inspection position P, the surface of the linear body S is irradiated with the laser light emitted from each of the light projecting units 1, 2, and 3. The entire angular range (entire circumference) of the surface of the linear body S at the inspection position P is divided into three equal angular ranges, and the laser light emitted from each of the light projecting units 1, 2 and 3 is divided for each angular range. It is irradiated.

In front of the inspection position P, a donut-shaped condensing member 4 for condensing the laser light reflected by the linear body S.
Are arranged so as to surround the linear body S. The light collecting member 4 is made of, for example, a transparent acrylic resin. The light received by the light collecting member 4 is incident on the photomultiplier tube 5.
The output of the photomultiplier tube 5 is sent to a control device (not shown). The control device performs a defect detection process based on the output of the photomultiplier tube 5 and displays the result on a display.

As shown in FIG. 3, in order to efficiently send the light incident on the light collecting member 4 to the photomultiplier tube 5, the light collecting member 4 is provided.
It is preferable that the light reflection film 7 is formed on the surface of (1) with the light incident portion 6 on which the reflected light from the surface of the linear body S is incident so that the light reflection surface faces inward. As the light reflecting film 7, a light reflecting tape or the like is used. In addition, the light collecting member 4
The light incident on the light collecting member 6 from the light incident portion 6 is reflected by a portion of the surface of the light collecting member 4 opposite to the light incident portion 6 (a portion facing the light incident portion 6).
In order to prevent the light from being emitted from, it is preferable to form irregularities on the surface of the light collecting member 4 opposite to the light incident portion 6.

FIG. 4 shows the structure of each of the light projecting units 1, 2, and 3. Since the configurations of the light projecting units 1, 2, and 3 are the same, the light projecting unit 13 will be described here as an example.

The light projecting portion 13 is a cylindrical body for slenderly expanding the laser light sent from the laser light source 8 through the optical fiber 9 to the corresponding angular range of the surface of the linear body S at the inspection position P. The lens 11 and the slitting member 12 for light adjustment for removing the peripheral portion of the light beam expanded by the cylindrical lens 11 are elongated. Figure 4
As shown in FIG. 5 and FIG. 5, the lip-shaped light beam Ba that has been elongated by the cylindrical lens 11 passes through the elongated rectangular slit 12a of the light regulating slit member 12 and becomes an elongated rectangular light beam Bb. The corresponding angular range of the surface of the filament is illuminated. The light adjusting slit member 12 removes a peripheral portion of the light beam Ba having variations in light intensity.

6 to 8 show a concrete structure of the flaw detector.

On the front surface and the rear surface of the casing 21 of the flaw detector, the linear body passage hole 2 for passing the linear body S is formed.
3, 22 are open. The linear body passage hole 22 on the rear surface of the casing 21 is an inlet side passage hole, and the linear body passage hole 23 on the front surface of the casing 21 is an outlet side passage hole. On the rear surface of the casing 21, an inlet side linear body guide member 24 having a truncated cone-shaped guide hole whose diameter decreases toward the front for guiding the linear body S to the inlet side passage hole 22 is attached. On the rear surface of the casing 21, an outlet side linear body guide member 25 having a frustoconical guide hole whose diameter decreases toward the front for guiding the linear body S that has passed through the outlet side passage hole 23 to the movement path L is attached. Has been.

A pair of left and right linear body guiding units 31 and 32 for guiding and supporting the linear body S are provided immediately inside the inlet side passage hole 22 in the casing 21. Each of the linear body guide units 31 and 32 includes a fixed base 33 fixed to the casing 21, and a movable base 34 movably supported by the fixed base 33 in a direction of approaching and separating from the moving path L.
And a guide roller 35 rotatably attached to the movable table 34. An annular groove into which the linear body S is fitted is formed on the outer peripheral surface of each guide roller 35.

The position of the movable base 34 of each linear body guiding unit 31, 32 can be adjusted by a screw mechanism 36. When the inspection is performed, the movable base 34 is positioned so that the linear body S is sandwiched by the bottom walls of the annular grooves of both guide rollers 35.

A pair of left and right linear body guide units 41 and 42 for guiding and supporting the linear body S are also arranged just inside the outlet side passage hole 23 in the casing 21. The structure of one linear body guiding unit 42 is the same as the structure of the linear body guiding units 31 and 32 described above, and the casing 2
The fixed base 43 fixed to 1 and the moving path L to the fixed base 43
The movable table 44 is movably supported in a direction in which the movable table 44 moves toward and away from the table, and a guide roller 45 rotatably attached to the movable table 44. The position of the movable base 44 can be adjusted by a screw mechanism.

The other linear body guiding unit 41 includes a fixed base 43 fixed to the casing 21, and a pair of front and rear movable bases movably supported by the fixed base 43 in a direction of approaching and separating from the moving path L. 51 and 52, and movable tables 51 and 52
And guide rollers 53 and 54 rotatably attached to the. The position of each movable table 51, 52 is the screw mechanism 5.
It can be adjusted by 5, 56.

A light projecting unit 60 is provided in front of the linear body guiding units 31, 32 on the side of the entrance-side passage hole 22. The light projecting unit 60 includes an annular light projecting portion support member 61 fixed to the casing 21, and a light projecting portion support member 6.
The three mounting members 62 mounted at intervals of 120 degrees on one side, the turntables 63 mounted on each mounting member 62, and the light projecting units 1, 2, and 3 mounted on each turntable 63. I have it. Each light emitting unit 1, 2,
Laser light is sent to the laser beam 3 from the above-mentioned single laser light source 8 not shown in FIGS.

A light receiving unit 70 is provided between the light projecting unit 60 and the linear body guiding units 41, 42 on the exit side passage hole 23 side. The light receiving unit 70 includes a pair of left and right guide bars 71, 72 fixed to the casing 21.
A support plate 73 movably mounted in the front-back direction.
The photomultiplier tube 5 attached to the support plate 73, and the condensing member 4 attached to the photomultiplier tube 5 by the jig 74.

A linear body passage hole is formed at a position corresponding to the movement path L of the support plate 73. The position of the support plate 73 is adjusted by the screw mechanism 75.

Next, referring to FIGS. 1 and 6 to 8,
The operation of the flaw detector will be described. It is assumed that the linear body S is moving along the moving path L in the direction of arrow A.
The light emitted from each of the light projecting units 1, 2, 3 is applied to the surface of the linear body S, the reflected light thereof is condensed on the condensing member 4, and the condensed light is sent to the photomultiplier tube 5. . The light sent to the photomultiplier tube 5 is multiplied by the photomultiplier tube 5 and extracted as an electric signal. The output of the photomultiplier tube 5 is sent to a control device (not shown) and a defect detection process is performed.

In the above embodiment, the entire angular range of the outer peripheral surface of the linear body S is divided into three angular ranges, and the three light projecting units 1, 2, 3 are provided to irradiate light in each angular range. Although provided, the entire angular range of the outer peripheral surface of the linear body S is divided into an arbitrary number of angular ranges other than 3, and the number of projections is equal to the number of divisions for irradiating light in each angular range. You may make it provide a part. Further, the present invention can be applied to an inspection object other than the upper linear body S as long as the inspection object has a circular or circular cross section.

In the above embodiment, the three light projecting units 1, 2, 3 are used.
By this, light can be simultaneously applied to the entire angular range of the surface of the linear body S, so that even if the moving speed of the linear body S is high, accurate defect detection can be performed. Further, the laser light emitted from the laser light source 8 is transmitted through the optical fiber 9 to the respective light projecting units 1, 2, 3
Since the light beam is transmitted to the laser beam, the light beam with less variation in intensity can be obtained, and the detection accuracy is improved. Furthermore, each light projecting unit 1,
In 2 and 3, since the light beam emitted from the cylindrical lens 11 is passed through the slit 12a, an elongated rectangular light beam with less variation in intensity is obtained, and the detection accuracy is improved.

As a method of detecting a defect by using the flaw detection device, the specular reflection light from the surface of the linear body S is collected.
To detect the defect based on a change in the light intensity of the specular reflection light, and a method in which only the diffused reflection light from the surface of the linear body S is incident on the light collecting member 4 to change the light intensity of the specular reflection light. There is a method of performing defect detection based on. Switching between these detection methods is performed by changing the position of the light collecting member 4. In the above embodiment, the position of the light collecting member 4 can be easily adjusted by the screw mechanism 75, so that the defect detection method can be easily switched.

The optimum irradiation angle of the laser beam onto the surface of the object to be inspected generally differs depending on the type of defect formed on the surface of the object to be inspected. In the above embodiment, each of the light projecting units 1, 2, 3 is
Since it is attached to the turntable 63, by adjusting the rotation angle position of the turntable 63,
It is possible to easily adjust the irradiation angle of each of the light projecting units 1, 2, and 3 to the surface of the object to be inspected. Therefore, it is possible to easily adjust the irradiation angle of the laser beam to the surface of the inspection object according to the type of defect formed on the surface of the inspection object.

By the way, when the light from each of the light projecting portions 1, 2, and 3 is obliquely applied to the surface of the linear body S, as shown in FIG. To be exact, the optical path length to the surface of the linear body S differs depending on the position within the irradiation range of each of the light projecting units 1, 2, and 3. For example, the optical path length r2 of the light emitted to the end of the irradiation range of the light projecting unit 1 is longer than the optical path length r1 of the light irradiated to the center of the irradiation range. In this way, if the optical path length differs depending on the position within the irradiation range of each of the light projecting units 1, 2, and 3, the intensity of the light emitted varies depending on the position within the irradiation range.

Therefore, as shown in FIG. 9 by taking the light projecting portion 1 as an example, the light emitted from the light projecting portion 1 is reflected by the concave mirror 80 to irradiate the surface of the linear body S, and the surface of the linear body S is exposed. The optical path lengths may be equalized in the entire irradiation range of the light projecting unit 1. By doing so, the intensity of the light emitted is equal over the entire irradiation range of the light projecting unit 1, and the detection accuracy can be improved.

As described above, instead of equalizing the optical path length from the light projecting portion 1 to the surface of the linear body S over the entire irradiation range, as shown in FIGS. 10 to 12, the shape of the light collecting member 90 is special. With the shape, the optical path length of the reflected light from the surface of the linear body S to the condensing member 4 is changed according to the position within the irradiation range, and the optical path length from the light projecting unit 13 to the condensing member 4 is irradiated. You may make it equal in the whole range.

The light-collecting member 90 has three curved portions 91, 92 which are curved rearwardly on the same virtual cylindrical surface.
And 93. The rearmost part of the curved portion 91 corresponds to the boundary of the irradiation range between the light projecting section 1 and the light projecting section 3. The rearmost part of the curved portion 92 corresponds to the boundary of the irradiation range between the light projecting section 2 and the light projecting section 3. The rearmost part of the curved portion 93 corresponds to the boundary of the irradiation range between the light projecting section 1 and the light projecting section 2. Further, the connecting portion between the curved portion 91 and the curved portion 92 is
It corresponds to the central position of the irradiation range of the light projecting unit 3. The connecting portion between the curved portion 92 and the curved portion 93 corresponds to the center position of the irradiation range of the light projecting unit 2. The connecting portion between the curved portion 93 and the curved portion 91 corresponds to the center position of the irradiation range of the light projecting unit 1.

[0039]

According to the present invention, accurate defect detection can be performed even if the speed of movement of the object to be inspected is high.

[Brief description of drawings]

FIG. 1 is a schematic perspective view showing a basic configuration of a flaw detection device.

FIG. 2 is a front view of each light projecting unit viewed from the inspection position side.

FIG. 3 is an enlarged perspective view from the back side showing a modified example of the ambient light member.

FIG. 4 is an enlarged plan view showing a configuration of a light projecting unit.

FIG. 5 is a diagram showing a shape and a slit of a light beam that has passed through a cylindrical lens.

FIG. 6 is a side view showing a specific configuration of the flaw detection device.

FIG. 7 is a partial plan view of FIG.

FIG. 8 is a rear view showing the light projecting unit of FIG.

FIG. 9 is a schematic configuration diagram showing a specific example for equalizing the optical path lengths from the light projecting unit to the irradiation position over the entire range of the irradiation range of the light projecting unit on the surface of the linear body.

FIG. 10 is a schematic configuration diagram showing a specific example for equalizing the optical path length from the light projecting unit to the light collecting member in the entire irradiation range.

11 is a front view of the light collecting member of FIG.

12 is a side view of the light collecting member of FIG.

FIG. 13 is an optical path length from the light projecting portion to the irradiation position depending on the position within the irradiation range of the light projecting portion on the surface of the linear body when the light from the light projecting portion is directly irradiated to the surface of the linear body in an oblique direction. And FIG.

[Explanation of symbols]

 1, 2 and 3 Light projecting unit 4, 90 Condensing member 5 Photomultiplier tube 8 Laser source 9 Optical fiber for light control 11 Cylindrical lens 12 Slit member for light control 12a Slit

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Shigeki Maeda 6-3-17-304 Shimoshinjo, Higashiyodogawa-ku, Osaka-shi, Osaka (72) Inventor, Kazuhiko Hiroshima 3550, Kidayo-cho, Tsuchiura-shi, Ibaraki Hitachi Cable, Ltd. Tsuchiura Plant Within

Claims (10)

[Claims] 1. A light-projecting means for irradiating light onto a surface of an object to be inspected, which has a circular or circular cross section, and a light receiving means for receiving light reflected from the surface of the object to be inspected. In a flaw detection device for detecting defects in the inspection object based on output, a plurality of light projecting means for irradiating light in each of the angular ranges obtained by dividing the entire angular range of the surface of the inspection object into a plurality of parts are provided. A flaw detection device characterized in that the plurality of light projecting means irradiate the entire angle range of the surface of the object to be inspected. 2. Each of the light projecting means comprises a laser light source and an optical system for converting a light beam emitted from the laser light source into an elongated light beam spreading in a corresponding angular range on the surface of the object to be inspected. The flaw detection device according to claim 1, wherein the flaw detection device is provided. 3. Each of the light projecting means comprises a laser light source, a light adjusting optical fiber into which light emitted from the laser light source enters from an input end, and a light beam emitted from the emitting end of the light adjusting optical fiber. 2. The flaw detection apparatus according to claim 1, further comprising: an optical system that converts the light into an elongated light beam that spreads in a corresponding angular range on the surface of the object to be inspected. 4. The flaw detection device according to claim 2, wherein the optical system is a cylindrical lens. 5. An optical system comprising: a cylindrical lens; and a slit member for adjusting light, which is arranged in front of the cylindrical lens and removes a peripheral portion of a light beam that has passed through the cylindrical lens. The flaw detection device according to claim 2, further comprising: 6. The optical system according to claim 2, wherein the optical system is rotatably mounted in a direction in which an irradiation angle of light emitted from the optical system onto the surface of the object to be inspected changes.
Alternatively, the flaw detection device described in 3. 7. The flaw detection device according to claim 1, wherein the light receiving means includes a doughnut-shaped light collecting member for collecting the reflected light from the surface of the object to be inspected. 8. The flaw detection apparatus according to claim 7, wherein a light reflecting film is formed on a portion of the surface of the light collecting member other than the light incident portion with the light reflecting surface facing inward. 9. The flaw detection device according to claim 7, wherein irregularities are formed in a portion of the surface of the light collecting member facing the light incident portion. 10. The light condensing member is attached so as to be movable in the axial direction of the object to be inspected, and a position where the light converging member can receive specularly reflected light from the object to be inspected and the object to be inspected. The flaw detection device according to any one of claims 7, 8 and 9, wherein a position where the diffused light from the body can be received by the light collecting member can be switched.