JP2005283301A - Metal ring defect detector - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To detect not only spot marks on a surface to be inspected but also an extremely wide and narrow line mark extended in the peripheral direction and width direction, by devising the irradiation direction of the surface to be inspected. <P>SOLUTION: A metal ring defect detector comprises light sources 31, 41 for irradiating the surface to be inspected of an inspection target 2 traveling in a fixed direction with light; a first waveguide 32 for guiding reflection light from the surface to be inspected to a first light receiving element 33 and a second waveguide 42 for guiding the reflection light to a second light receiving element 43; a differential value computing means for calculating the differential value between an electric signal output from the first light receiving element or an electric signal correlated to the electric signal, and an electric signal output from the second light receiving element or the electric signal related to the electric signal; and a discrimination means for discriminating the presence and absence of defects on the surface to be inspected by comparing the differential value with a prescribed threshold. Light from the light sources 31, 41 is applied in the traveling direction of the inspection target at approximately 45° crossing angles (ϕc, ϕd). <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention detects a defect in an endless belt-like metal ring, which is one of the parts constituting a belt of a V-belt type continuously variable transmission (hereinafter referred to as “CVT belt”) mounted on a vehicle such as an automobile. The present invention relates to a metal ring defect detection device.

  As a CVT belt, for example, as described in Non-Patent Document 1, steel elements are continuously fitted in a stack of a large number of thin metal rings having a thickness of about 0.2 mm. An integrated structure is known.

  FIG. 8 is an external view of the CVT belt. In this figure, a CVT belt 1 is composed of a plurality of (for example, about 400) steel elements 4 on a double belt laminate 3 in which a large number (for example, about 12) of metal rings 2 are stacked. The element laminate 5 is assembled and supported.

  FIG. 9 is a schematic manufacturing process diagram of the CVT belt 1. In this figure, end portions 6 a of thin plates 6 of “super tough steel” (details will be described later) are abutted and welded to form a ring-shaped drum 7. Next, the drum 7 is cut into a circular shape by a predetermined width and rolled to form a metal ring 2 having a basic circumference.

  Next, after the above-described metal ring 2 is subjected to a solution treatment or the like, a circumference correction process is performed to give each metal ring 2 a required circumference corresponding to the place where the CVT belt 1 is laminated.

  Next, the metal ring 2 after the circumference correction is subjected to aging treatment or nitriding treatment to increase the surface hardness, and then the presence or absence of surface defects in the metal ring 2 is inspected, and the metal ring 2 that has passed the inspection. Are sequentially laminated, and the element 4 is fitted into the laminated body and integrated to complete the CVT belt 1.

  As described above, “super tough steel” is used for the metal ring 2 of the CVT belt 1. Examples of super tough steel suitable for the CVT belt 1 include maraging steel as described in Patent Document 1. Maraging steel is suitable for use in the CVT belt 1 because of its excellent toughness, but it is not sufficient in terms of fatigue strength. In order to compensate for this fatigue strength, for example, nitriding treatment as described in Patent Document 2 is performed.

  As described in Non-Patent Document 2, the nitriding treatment refers to a treatment for forming a hardened layer (cured film) of iron nitride by infiltrating nitrogen into the steel surface. A salt bath nitriding method, a tuftride method, a plasma nitriding method, a gas soft nitriding method, and the like are known. However, in mass production parts such as the CVT belt 1, the gas soft nitriding method is generally used in terms of cost. According to this method, a hardened layer having a hardness of about Hv 400 to 700 can be formed on the steel surface with a depth of about 8 to 15 μm.

  Thus, although it is the metal ring 2 which formed the hardened layer on the surface, the hardness is not perfect (Hv400-700 grade), and the metal rings 2 are rubbed and collided with each other, or interference with other objects. In many cases, the surface is often unintentionally scratched (hereinafter referred to as “defect”).

  FIG. 10 is a conceptual configuration diagram of a “defect detection device” (hereinafter referred to as a conventional device) described in Patent Document 3, for example. In this conventional apparatus, a plurality of illumination guides for guiding the irradiation light from the inspection light source 8 “directly above” the surface 9 to be inspected (the outer surface or the inner surface of the metal ring 2) moving in a certain direction. At least two light receiving portions that are alternately arranged between the optical paths 10a to 10c (optical fibers) and the light guide paths 10a to 10c for illumination and guide the reflected light Pa and Pb from the surface 9 to be inspected to the light receiving portions 11a and 11b. The light guide paths 12a and 12b (optical fibers) are provided, and the point that the two light guide paths 12a and 12b for light reception are spaced apart by a slight distance L is a point.

  With this configuration, when there is no defect such as a scratch on the surface 9 to be inspected, the reflected light Pa and Pb guided by the two light receiving light guides 12a and 12b have substantially the same intensity with the light receiving unit 11a, On the other hand, if there is a defect on the surface 9 to be inspected, the reflected light of the defective portion is reduced (the amount of light is reduced due to irregular reflection), so the reflection guided by the two light receiving light guides 12a and 12b. A difference occurs between the light beams Pa and Pb, and the presence or absence of a defect can be automatically determined from the magnitude of the difference.

  FIG. 11 is a conceptual diagram of defect detection in a conventional apparatus. In FIG. 2A, the two light receiving light guides 12a and 12b are separated by a distance L, and the surface 9 to be inspected moves in a constant direction at a speed V, for example.

  When the defect 13 is present on the surface 9 to be inspected, first, the end face of the right light receiving light guide 12b faces the defect 13, and after a certain period of time, the end face of the left light receiving light guide 12a is defective. Opposite to 13 '. Here, the defect 13 ′ is the defect 13 after moving at the speed V.

  The light whose amount of light has decreased due to the irregular reflection of the defect 13 (13 ′) is first received by the right light receiving unit 11b, and is received by the left light receiving unit 11a after a certain period of time. FIG. 5B shows the output signal waveform of the right light receiving section 11b at this time, and FIG. 5C shows the output signal waveform of the left light receiving section 11a.

  The numbers (“50” and “0”) shown in these signal waveforms represent signal levels for convenience of explanation. For example, “50” represents a strong reflected light level from the defect-free portion of the surface 9 to be inspected, and “0” represents a weak reflected light level from the portion of the defect 13 (13 ′) on the surface 9 to be inspected.

  Now, when calculating the difference between these two signal waveforms, that is, “[waveform of FIG. (B)] −“ waveform of FIG. (C) ”], the waveform (hereinafter“ difference value ”) of FIG. Is obtained).

  The difference value is “0” when both “the waveform in FIG. 5B” and “the waveform in FIG. 5C” are “50”, and “the waveform in FIG. “-50” when “the waveform of FIG. 5C” is “50”, and “the waveform of FIG. 5B” is “50” and “the waveform of FIG. When “0”, it becomes “50”.

  Therefore, an appropriate threshold value such as a high side threshold value (SL_H) slightly smaller than “50” and a low side threshold value slightly smaller than “−50” (SL_H) SL_L), signals 14 and 14 'corresponding to the defects 13 and 13' can be taken out, respectively, and a defect detection alarm can be issued using the signals 14 and 14 '. .

Tomohiro Miyaji “Extracting the Performance of the Ideal Transmission CVT”, [online], [Search August 25, 2002], Internet <URL: http://www.idemitsu.co.jp/lube /cvt/cvtbody2.html> DESIGN MECHANIC for mechanical engineers & designers “nitriding”, [online], [February 28, 2004], Internet <URL: http://homepage1.nifty.com/seas/database/heat/nitro.htm> JP 11-1117017 A JP-A-11-200010 Japanese Patent Laid-Open No. 11-248637

However, when the above conventional apparatus is applied, there are the following disadvantages.
That is, as apparent from the configuration of FIG. 10, the surface 9 to be inspected in the conventional apparatus is illuminated through the light guides 10a to 10c for illumination, and the optical axes of the light guides 10a to 10c for illumination. Are arranged along a substantially vertical direction of the surface 9 to be inspected. That is, the surface 9 to be inspected is illuminated from “directly above”.

  For this reason, among various defects (scratches) present on the surface 9 to be inspected, a scratch having a relatively large area (hereinafter referred to as a “spot scratch”) can be made conspicuous from the surroundings by the illumination light. Although it can be detected without any trouble by the conventional apparatus, a straight thin scratch, for example, when the surface 9 to be inspected is the surface of the metal ring 2, a straight scratch attached along the circumferential direction of the metal ring 2, About the straight damage | wound attached along the width direction of the metal ring 2, it was not able to be made conspicuous from the surroundings with illumination light, and even the said conventional apparatus might not be able to be detected.

  FIG. 12 is a diagram illustrating an example of spot flaws and straight flaws. In this figure, on the surface of the metal ring 2, in addition to the spot flaw 15 having a relatively large area, a straight flaw 16 having a very narrow width extending in the circumferential direction of the metal ring 2 and a very wide width extending in the width direction of the metal ring 2. Is attached with a narrow straight scratch 17.

  Among such scratches, the spot scratch 15 having a relatively large area is easy to discriminate because a wide range of irregular reflection occurs in the large area even when illuminated from directly above the surface to be inspected. The straight flaws 16 and 17 having a narrow width are difficult to discriminate because they are less likely to cause irregular reflection. Therefore, the defects (straight flaws 16 and 17) may not be detected easily even if a conventional apparatus is used.

  Therefore, the object of the present invention is to devise the illumination direction of the surface to be inspected so that not only spot scratches on the surface to be inspected but also extremely narrow line scratches extending in the circumferential direction and the width direction can be detected. The object is to provide a metal ring defect detection device.

The present invention provides a light source that illuminates a surface to be inspected of an inspection object that moves in a fixed direction, a first light guide that guides reflected light from the surface to be inspected to a first light receiving element, and the reflected light to a second light source. A second light guide path leading to the light receiving element, an electric signal output from the first light receiving element or an electric signal correlated with the electric signal, and an electric signal output from the second light receiving element or the electric signal thereof A difference value calculating means for calculating a difference value with an electric signal correlated with the metal, and a determining means for comparing the difference value with a predetermined threshold value to determine the presence or absence of a defect on the surface to be inspected. The present invention relates to a ring defect detection device, which is characterized in that light from the light source is irradiated at an intersection angle of approximately 45 degrees with respect to the moving direction of the inspection object.
Preferably, the inspection object is an endless belt-shaped metal ring, and the light from the light source is irradiated at an intersection angle of approximately 45 degrees with respect to a circumferential direction of the metal ring. It is a feature.
Alternatively, the present invention provides a light source that illuminates a surface to be inspected of an inspection object that moves in a fixed direction, a first light guide that guides reflected light from the surface to be inspected to a first light receiving element, and the reflected light. A second light guide path leading to the second light receiving element, an electric signal output from the first light receiving element or an electric signal correlated with the electric signal, and an electric signal output from the second light receiving element or the same Difference value calculating means for calculating a difference value between the electric signal correlated with the electric signal and a determining means for comparing the difference value with a predetermined threshold value to determine the presence or absence of a defect on the surface to be inspected. In the metal ring defect detection apparatus, the light from the light source is irradiated at an intersection angle of approximately 90 degrees with respect to the moving direction of the inspection object,
Preferably, the inspection object is an endless belt-shaped metal ring, and irradiates light from the light source at an intersection angle of about 90 degrees with respect to a circumferential direction of the metal ring. To do.
Alternatively, the present invention provides a light source that illuminates a surface to be inspected of an inspection object that moves in a fixed direction, a first light guide that guides reflected light from the surface to be inspected to a first light receiving element, and the reflected light. A second light guide path leading to the second light receiving element, an electric signal output from the first light receiving element or an electric signal correlated with the electric signal, and an electric signal output from the second light receiving element or the same Difference value calculating means for calculating a difference value between the electric signal correlated with the electric signal and a determining means for comparing the difference value with a predetermined threshold value to determine the presence or absence of a defect on the surface to be inspected. In the metal ring defect detection apparatus, the light from the light source is irradiated in parallel with the moving direction of the inspection object,
Preferably, the inspection object is an endless belt-shaped metal ring and irradiates light from the light source in parallel with a circumferential direction of the metal ring.

According to the present invention, the light from the light source is irradiated at an intersection angle of approximately 45 degrees (see φc and φd in FIG. 2) with respect to the moving direction of the inspection object. In addition to scratches, line wounds extending along the direction of movement of the inspection object (see line wounds 16 in FIG. 12) and line wounds extending along the width direction of the inspection object (FIG. 12). Also, the defect portion can be made conspicuous by irradiating light at the crossing angle (approximately 45 degrees). Therefore, since the amount of reflected light is reduced due to irregular reflection at any scratched part, those defects (spot scratches and line scratches) can be detected without hindrance by comparison with the reflected light of the non-defective part.
Further, if the light from the light source is irradiated at a crossing angle of about 90 degrees with respect to the moving direction of the inspection object, a line wound extending along the moving direction of the inspection object is detected, It is possible not to detect (neglect) the flaws extending along the width direction of the inspection object.
Further, if the light from the light source is irradiated in parallel with the moving direction of the inspection object, contrary to the above, the line flaw extending along the moving direction of the inspection object is not detected (ignored). On the other hand, it is possible to detect a line wound extending along the width direction of the inspection object.

  Embodiments of the present invention will be described below with reference to the drawings. It should be noted that the specific details or examples in the following description and the illustrations of numerical values, character strings, and other symbols are only for reference in order to clarify the idea of the present invention, and the present invention may be used in whole or in part. Obviously, the idea of the invention is not limited. In addition, a well-known technique, a well-known procedure, a well-known architecture, a well-known circuit configuration, and the like (hereinafter, “well-known matter”) are not described in detail, but this is also to simplify the description. Not all or part of the matter is intentionally excluded. Such well-known matters are known to those skilled in the art at the time of filing of the present invention, and are naturally included in the following description.

  FIG. 1 is a conceptual configuration diagram of a metal ring defect detection apparatus. The metal ring defect detection device 20 includes a fixed position driving pulley 22 that is rotationally driven by a ring rotation driving motor 21, a position variable driven pulley 23 that is spaced apart on the same rotational plane as the driving pulley 22, a predetermined pulley. A load body 24 having a mass (for example, 80 kg) and a defect detection unit 25 are included. In addition to the driving pulley 22 and the driven pulley 23, one or a plurality of guide pulleys may be provided, but the minimum necessary pulleys are the driving pulley 22 and the driven pulley 23. .

  When inspecting the metal ring 2 to be inspected, first, the driven pulley 23 is set to the initial position (the position of the one-dot chain line a), and the metal ring 2 is spanned between the drive pulley 22 and the driven pulley 23, Next, the load body 24 is attached to the driven pulley 23 and the driven pulley 23 is moved, thereby applying a required tension to the metal ring 2. In this state, the ring ring driving motor 21 is driven to circulate the metal ring 2 in a certain direction (arrow A direction), and the defect detection unit 25 is used to detect a defect of the metal ring 2.

  FIG. 2 is a conceptual configuration diagram of the defect detection unit 25. In this figure, the defect detection unit 25 includes at least two optical sensor units 30 and 40 (hereinafter, “A system optical inspection unit 30”, “B system optical inspection unit 40”, or simply “A system 30”). , Referred to as “B system 40”) and a determination unit 50. The reason why the “at least two” optical sensor units 30 and 40 are provided will be described later.

  The A system 30 and the B system 40 have the same configuration. That is, the A system 30 (B system 40) includes a light source 31 (41) that illuminates the surface (surface to be inspected) of the metal ring 2 as an inspection object from a “predetermined direction” (details will be described later), and the object to be inspected. A light receiving optical fiber 32 (42) having an optical axis in the vertical direction of the surface and having an end surface slightly spaced from the surface to be inspected and parallel to each other with a distance L, and a light receiving optical fiber 32 (42) And a light receiving element 33 (43) for converting the reflected light Pa (Pb) from the surface to be inspected guided by the above into an electric signal Sa (Sb). The light receiving optical fiber 32 of the A system 30 constitutes the “first light guide” described in the gist of the invention, and the light receiving element 33 of the A system 30 constitutes the “first light receiving element” described in the gist. The light receiving optical fiber 42 of the B system 40 constitutes the “second light guide” described in the same summary, and the light receiving element 43 of the B system 40 constitutes the “second light receiving element” described in the same summary. .

  As described above, the light source 31 (41) of the present embodiment is characterized in that it illuminates the surface to be inspected of the metal ring 2 as the inspection object from a “predetermined direction”. This “predetermined direction” will be described. Now, let the optical axes of the light source 31 (41) be P31 and P41, respectively, and the optical axes P31 and P41 and the surface of the metal ring 2 (covered) as shown in FIG. When the angles (incident angles of irradiation light) made with the inspection surface are φa and φb, φa and φb are about 45 degrees, respectively. As shown in FIG. 5B, when the angles (intersection angles) formed between the optical axes P31 and P41 and the center line L2 extending in the circumferential direction of the metal ring 2 are φc and φd, φc and φd are Each is about 45 degrees.

  However, the former “φa = φb≈45 degrees” is a preferable example, and the angle is not particularly limited. In other words, the incident angle of the irradiation light on the surface to be inspected should be in the range of 0 ° to 90 °, and 45 ° is just one example, but the latter “φc = φd≈45 °” Not only spot scratches (see spot scratch 15 in FIG. 12) applied to the inspection surface, but also straight scratches extending in the circumferential direction (see straight scratch 16 in FIG. 12), and straight scratches extending in the width direction (straight scratch in FIG. 12). 17) is an indispensable matter for detecting without trouble, and is a point of this embodiment. The principle of detecting spot flaws and straight flaws will be described later.

  Based on the electrical signal Sa output from the light receiving element 33 of the A system 30 and the electrical signal Sb output from the light receiving element 43 of the B system 40, the determination unit 50 determines whether there is a defect on the inspection surface of the metal ring 2. The basic principle is that the intensity of light incident on the two light receiving elements 33 (43) is substantially the same when there is no defect on the surface to be inspected, and is different when there is a defect. And taking the difference value of the electrical signals Sa and Sb output from the two light receiving elements 33 (43) and determining that the surface to be inspected is defective when the difference value is large. It is.

  To explain this a little more clearly, now, when there is no defect on the surface to be inspected of the metal ring 2, the surface to be inspected is a smooth surface, and the light irradiated onto the surface to be inspected is uniform on the smooth surface. Reflected in the same manner, hardly any irregular reflection occurs. For this reason, the intensities of the light incident on the two light receiving elements 33 (43) are substantially the same. In this case, the difference value between the electric signals Sa and Sb is substantially “0”.

  On the other hand, when the surface to be inspected of the metal ring 2 has a defect, the light irradiated onto the surface to be inspected is irregularly reflected at the defect location, and therefore the light receiving element 33 (through the light receiving optical fiber 32 (42). The intensity of the light guided to 43) decreases by the amount of the irregular reflection. At this time, if the distance L between the light receiving optical fibers 32 (42) of the A system 30 and the B system 40 is sufficiently larger than the size of the defect, the light receiving optical fiber of one system (for example, the light receiving of the A system 30). When the optical fiber 32) guides light whose intensity has been lowered due to the influence of the defect, the other light-receiving optical fiber (light-receiving optical fiber 42 of the B system 40) has light whose intensity does not decrease (that is, the defect) Intense reflected light from a smooth surface with no light). Therefore, in this case, since the electric signal Sa <the electric signal Sb, the difference value is clearly larger than that in the normal state (Sa = Sb).

  Based on the above principle, “the difference value between the electric signals Sa and Sb output from the two light receiving elements 33 (43) is taken, and when the difference value is large, it is determined that the surface to be inspected is defective”. Can do.

  The reason for requiring at least two systems (A system 30 and B system 40) is as follows. From the above description of the principle, when there is no defect on the surface to be inspected, the electric signal Sa (or Sb) output from any system becomes a “large value”. When there is a defect on the surface to be inspected, any system receives light reflected from the defect (light whose intensity has decreased by the amount of irregular reflection) and is output from that system. The electric signal Sa (or Sb) has a “small value”.

  Basically, it is possible to determine a defect by distinguishing between these “large value” and “small value”. However, with this alone, stable determination cannot be expected, and there is a problem in practical use. This is because the entire surface of the object to be inspected, particularly the metal ring 2 used in the CVT belt 1, is matted by nitriding, and the degree of matting is constant for each product (or lot). This is because the “large value” of the electrical signal Sa (or Sb) serving as a reference at the time of normality varies. By configuring the optical sensor unit with “at least two systems” and taking the “difference value” of the electrical signals Sa (and Sb) output from those systems, the influence of the above-mentioned variation is eliminated, A stable determination can be made to make it practical.

  FIG. 3 is a block diagram of the determination unit 50. In this figure, the determination unit 50 includes an A-system amplifier 51, a B-system amplifier 52, an A-system AGC circuit 53, a B-system AGC circuit 54, a difference calculation section 55 (difference value calculation means), and a high side threshold. A value determination unit 56 (determination unit), a low-side threshold determination unit 57 (determination unit), an alarm signal generation unit 58, and the like are configured.

  The A-system amplifier 51 amplifies the electric signal Sa output from the A-system light receiving element 33, and the amplification factor is controlled to increase or decrease by the output of the A-system AGC circuit 53. The A-system AGC circuit 53 extracts a low-pass filter 59 that extracts only a low-frequency component including a direct current component from the output signal of the A-system amplifier 51, and the difference between the output of the low-pass filter 59 and a predetermined reference voltage REF1. The A-system amplifier 51 amplifies the electric signal Sa with an amplification factor corresponding to the AGC voltage. The purpose of this AGC voltage is to remove the “fluctuation” of the low-frequency component contained in the electrical signal Sa (mainly caused by the “surface shake” of the metal ring 2).

  Similarly to the A-system amplifier 51, the B-system amplifier 52 also amplifies the electric signal Sb output from the B-system light receiving element 43, and the amplification factor is the output of the B-system AGC circuit 54. Increase / decrease control is performed by. The B-system AGC circuit 54 extracts a low-pass filter 61 that extracts only a low-frequency component including a DC component from the output signal of the B-system amplifier 52, and the difference between the output of the low-pass filter 61 and a predetermined reference voltage REF1. The B-system amplifier 52 amplifies the electric signal Sb at an amplification factor corresponding to the AGC voltage. The purpose of this AGC voltage is the same as described above, and is to remove the “fluctuation” of the low frequency component included in the electric signal Sb.

  The difference calculation unit 55 calculates a difference value Sd (Sd = [Sa_51] − [Sb_52]) between the electric signal Sa_51 output from the A-system amplifier 51 and the electric signal Sb_52 output from the B-system amplifier 52. It is.

  The high-side threshold determination unit 56 compares the difference value Sd calculated by the difference calculation unit 55 with a predetermined high-side threshold SL_H, and becomes a high-side determination result signal that is active when Sd> SL_H. Sc_H is output, and the low-side threshold determination unit 57 compares the difference value Sd with a predetermined low-side threshold SL_L, and outputs a low-side determination result signal Sc_L that is active when Sd> SL_L. Output. The alarm signal generator 58 outputs an alarm signal ALM indicating detection of a defect on the inspection surface when one of these two determination result signals (Sc_H, Sc_L) is active.

  As described above, the problem of the present invention is that, by devising the illumination direction of the surface to be inspected, not only spot scratches on the surface to be inspected, but also extremely narrow lines extending in the circumferential direction and the width direction. The object is to provide a metal ring defect detection device capable of detecting flaws.

  Hereinafter, this point will be described. As described above, the light source 31 (41) of the present embodiment is characterized in that it illuminates the surface to be inspected of the metal ring 2 that is the inspection object from a “predetermined direction”. Specifically, the “predetermined direction” is defined by angles (incident angles of irradiation light) φa and φb formed by the optical axes P31 and P41 of the light source 31 (41) and the surface of the metal ring 2 (surface to be inspected). Each angle is about 45 degrees, and angles (intersection angles) φc and φd formed by the optical axes P31 and P41 and the center line L2 extending in the circumferential direction of the metal ring 2 are each about 45 degrees. .

  As described above, the basic principle of defect detection in the determination unit 50 is that “the intensity of light incident on the two light receiving elements 33 (43) is substantially the same when there is no defect on the surface to be inspected. Focusing on the difference when there is, the difference between the electric signals Sa and Sb output from the two light receiving elements 33 (43) is taken, and when the difference is large, the surface to be inspected has a defect. It is determined that there is. In other words, in the defect-free part of the surface to be inspected, the light irradiated to the surface to be inspected is uniformly reflected by a smooth surface, but in the defective part, the amount of reflected light is reduced due to irregular reflection, so the defect-free part and the defect The defect is detected based on the difference in the amount of reflected light at the part.

  FIG. 4 is a conceptual view of spot spot 15 detection. As shown in this figure, in the present embodiment, irradiation light from the light source 31 (41) is irradiated at an incident angle (φa, φb) of about 45 degrees, and the center line extending in the circumferential direction of the metal ring 2 L2 is also irradiated at an intersection angle (φc, φd) of about 45 degrees. For this reason, in the non-defect portion of the surface to be inspected (the portion other than the spot scratch 15), the irradiation light is uniformly reflected at the same angle as the incident angle (about 45 degrees). ) Causes irregular reflection, the amount of reflected light is reduced by the amount of irregular reflection, and this spot flaw 15 can be detected without any trouble by the determination unit 50 according to the basic principle.

  On the other hand, FIGS. 5 and 6 are detection conceptual diagrams of the straight scratches 16 and 17. In these figures, in the defect-free portion (portion other than the straight scratches 16 and 17) of the surface to be inspected, the irradiation light from the light source 31 (41) is incident on an incident angle (about 45 degrees), as with the spot scratch 15 described above. Are uniformly reflected at the same angle, and irregular reflection occurs at the defective portion (the portions of the straight scratches 16 and 17).

  In FIG. 5, the straight scratch 16 is a straight and extremely thin scratch attached along the circumferential direction of the metal ring 2. Further, in FIG. 6, the straight scratch 17 is a linear and extremely thin scratch attached along the width direction of the metal ring 2. For this reason, even if these straight scratches 16 and 17 are irradiated with light from directly above (directly above the drawing) as in the prior art, since the scratch width is very narrow, irregular reflection hardly occurs. The straight scratches 16 and 17 cannot be conspicuous.

  On the other hand, as in this embodiment, the light from the light source 31 (41) is irradiated at an incident angle (φa, φb) of about 45 degrees with respect to the surface to be inspected, and the circumferential direction of the metal ring 2 In contrast, if irradiation is performed at an intersection angle (φc, φd) of about 45 degrees, irregular reflection can be easily generated, and the straight scratches 16 and 17 can be made conspicuous accordingly. As a result, according to the basic principle described above, the straight line scratches 16 and 17 can be detected by the determination unit 50 without any trouble.

  Therefore, in this embodiment, since the illumination direction of the surface to be inspected is devised as described above, not only the spot scratch 15 attached to the surface to be inspected, but also a very narrow line scratch 16 extending in the circumferential direction and the width direction. , 17 can be detected, and a metal ring defect detecting device can be provided.

  In the above embodiment, the light from the light source 31 (41) is irradiated at an intersecting angle (φc, φd) of about 45 degrees with respect to the circumferential direction of the metal ring 2. This is an indispensable matter for detecting both the straight scratch 16 attached along the circumferential direction of the metal ring 2 and the straight scratch 17 along the width direction of the metal ring 2. If only one of the straight scratches is detected, the following may be performed.

  FIG. 7 is a conceptual diagram in the case of detecting only one of the straight flaw 16 attached along the circumferential direction of the metal ring 2 and the straight flaw 17 along the width direction of the metal ring 2. In FIG. 5A, the optical axes P31 and P41 of the light source 31 (41) are orthogonal to the center line L2 extending in the circumferential direction of the metal ring 2 at approximately 90 degrees. That is, φc and φd are about 90 degrees.

  In this way, the light from the light source 31 (41) is irradiated in a substantially orthogonal direction with respect to the linear scratch 16 attached along the circumferential direction of the metal ring 2, so that the linear scratch 16 is diffusely reflected. However, since the linear scratch 17 attached along the width direction of the metal ring 2 is irradiated in the extending direction of the linear scratch 17, irregular reflection hardly occurs.

  As a result, as shown in the figure, when the optical axes P31 and P41 of the light source 31 (41) are orthogonal to the central line L2 extending in the circumferential direction of the metal ring 2 at approximately 90 degrees, the metal ring 2 The straight scratch 16 attached along the circumferential direction of the metal ring 2 can be detected, while the straight scratch 17 attached along the width direction of the metal ring 2 can be prevented from being detected.

  Similarly, in FIG. 2B, the optical axes P31 and P41 of the light source 31 (41) are parallel to the center line L2 extending in the circumferential direction of the metal ring 2. That is, the crossing angles (φc, φd) are almost 0 degrees.

  In this way, light from the light source 31 (41) is irradiated in a substantially orthogonal direction with respect to the linear scratch 17 attached along the width direction of the metal ring 2, so that irregular reflection is caused in the linear scratch 17. However, since the linear scratch 16 attached along the circumferential direction of the metal ring 2 is irradiated in the extending direction of the linear scratch 16, irregular reflection hardly occurs.

  As a result, when the optical axes P31 and P41 of the light source 31 (41) are parallel to the center line L2 extending in the circumferential direction of the metal ring 2 as shown in the drawing, the width of the metal ring 2 is increased. It is possible to detect the straight flaw 17 attached to the metal ring 2, while preventing the straight flaw 16 attached along the circumferential direction of the metal ring 2 from being detected.

  In addition, this invention is not limited to said embodiment, Of course, various modifications and development examples are included in the range of the technical thought, for example, it may be as follows.

  In the above embodiment, the surface to be inspected is the “front surface” of the metal ring 2, but may be the “back surface” of the ring.

  Moreover, in said embodiment, although the light from the light sources 31 and 41 is directly irradiated to the to-be-inspected surface, you may irradiate indirectly via optical elements, such as an optical lens, for example.

  Moreover, in said embodiment, although the optical sensor part is made into two systems (A system 30, B system 40), it is good also as multiple systems exceeding two, and also when setting it as multiple systems exceeding two. Each system may be arranged in the circumferential direction and the width direction of the metal ring 2 (two-dimensional arrangement).

  In the above embodiment, the reflected light from the surface to be inspected is guided to the light receiving elements 33 and 43 via the light receiving optical fibers 32 and 42. The use of this "optical fiber" is the best mode of the embodiment. It only shows. In short, any “light guide” that can guide the reflected light from the surface to be inspected to the light receiving elements 33 and 43 with as little loss as possible can be used. For example, if the loss and flexibility are ignored or neglected, it is made of glass. Or a simple light guide made of plastic or the like.

It is a notional block diagram of a metal ring defect detection device. 3 is a conceptual configuration diagram of a defect detection unit 25. FIG. 3 is a block diagram of a determination unit 50. FIG. FIG. 3 is a conceptual diagram of detection of a spot flaw 15. FIG. 6 is a conceptual diagram of detection of a straight flaw 16. FIG. 6 is a conceptual diagram of detection of a linear scratch 17. FIG. 6 is a conceptual diagram in the case of detecting only one of a straight scratch 16 attached along the circumferential direction of the metal ring 2 and a straight scratch 17 along the width direction of the metal ring 2. It is an external view of a CVT belt. 3 is a schematic manufacturing process diagram of the CVT belt 1. FIG. It is a conceptual block diagram of a conventional apparatus. It is a conceptual diagram of defect detection in a conventional apparatus. It is a figure which shows the example of a spot wound and a linear wound.

Explanation of symbols

φc Crossing angle φd Crossing angle 31 Light source 32 Optical fiber for receiving light (first light guide)
33 Light receiving element (first light receiving element)
41 Light source 42 Optical fiber for light reception (second light guide path)
43 Light receiving element (second light receiving element)
55 Difference calculation part (difference value calculation means)
56 High-side threshold judgment unit (discrimination means)
57 Low-side threshold judgment unit (discrimination means)

Claims (6)

A light source that illuminates the surface to be inspected of the inspection object moving in a certain direction;
A first light guide that guides reflected light from the surface to be inspected to the first light receiving element and a second light guide that guides the reflected light to the second light receiving element;
A difference value between an electric signal output from the first light receiving element or an electric signal correlated with the electric signal and an electric signal output from the second light receiving element or an electric signal correlated with the electric signal is calculated. Difference value calculation means;
In the metal ring defect detection apparatus comprising a determination unit that compares the difference value with a predetermined threshold value to determine the presence or absence of a defect on the surface to be inspected.
The metal ring defect detection apparatus, wherein the light from the light source is irradiated at an intersection angle of about 45 degrees with respect to the moving direction of the inspection object. The inspection object is an endless belt-shaped metal ring, and irradiates light from the light source at an intersection angle of approximately 45 degrees with respect to a circumferential direction of the metal ring. The metal ring defect detection device according to 1. A light source that illuminates the surface to be inspected of the inspection object moving in a certain direction;
A first light guide that guides reflected light from the surface to be inspected to the first light receiving element and a second light guide that guides the reflected light to the second light receiving element;
A difference value between an electric signal output from the first light receiving element or an electric signal correlated with the electric signal and an electric signal output from the second light receiving element or an electric signal correlated with the electric signal is calculated. Difference value calculation means;
In the metal ring defect detection apparatus comprising a determination unit that compares the difference value with a predetermined threshold value to determine the presence or absence of a defect on the surface to be inspected.
A metal ring defect detecting device, wherein the light from the light source is irradiated at an intersection angle of approximately 90 degrees with respect to the moving direction of the inspection object. The inspection object is an endless belt-shaped metal ring and irradiates light from the light source at an intersection angle of approximately 90 degrees with respect to a circumferential direction of the metal ring. 3. The metal ring defect detection device according to 3. A light source that illuminates the surface to be inspected of the inspection object moving in a certain direction;
A first light guide that guides reflected light from the surface to be inspected to the first light receiving element and a second light guide that guides the reflected light to the second light receiving element;
A difference value between an electric signal output from the first light receiving element or an electric signal correlated with the electric signal and an electric signal output from the second light receiving element or an electric signal correlated with the electric signal is calculated. Difference value calculation means;
In the metal ring defect detection apparatus comprising a determination means for comparing the difference value and a predetermined threshold value to determine the presence or absence of defects on the surface to be inspected,
A metal ring defect detection apparatus, wherein the light from the light source is irradiated in parallel with a moving direction of the inspection object. 6. The metal ring defect detection according to claim 5, wherein the inspection object is an endless belt-shaped metal ring, and irradiates light from the light source in parallel with a circumferential direction of the metal ring. apparatus.

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