JP2013011560A - Device for detecting hole defects of steel strips - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a device for detecting hole defects of steel strips that has diagnostic functions of a projector and an optical receiver.SOLUTION: A device for detecting hole detects of steel strips comprises a projector 2 and an optical receiver 3 that are arranged on and under a continuously conveyed steel strip 1, a welding hole detector 5 arranged a little more upstream therefrom, a tracking device 6, a hole defect detecting control device 7, and a display device 8. The hole defect detecting control device 7 includes a hole defect detecting part 71 for constantly detecting whether or not there is a hole defect in the steel strip 1, a projector diagnosing part 72 for constantly diagnosing the projector 2, and an optical receiver diagnosing part 73 for diagnosing the optical receiver 3 at a predetermined timing. The optical receiver diagnosing part 73 diagnoses the optical receiver on the basis of an optical detection signal from a photo-detector of the optical receiver, by making diagnostic light incident to the photo-detector of the optical receiver, at the almost same time as the timing that a hole provided on a welding part between coils of the steel strip 1 is detected as a hole defect, or the timing that the hole passes above a light-receiving port and the welding part is predicted to exist above the light-receiving port.

Description

  In the present invention, for example, a plurality of sets of light projectors and light receivers are arranged on the upper and lower sides of a steel belt that is continuously conveyed, and light passing through a hole defect in the steel belt is received by the light receiver. The present invention relates to a hole defect detection device for a steel strip that detects a hole defect in the strip.

Conventionally, in a production line for cold-rolled steel sheets, a projector and a receiver are arranged above and below the steel strip that is continuously conveyed, and the light that has passed through the hole defect in the steel strip from the projector is received by the receiver. A hole defect in a steel strip is detected by receiving light (see Patent Document 1 and the like). Laser light is used as the light source of the projector, and a large number of projectors and light receivers are arranged so as to cover the entire width of the steel strip.
In this hole defect detection device, if all the projectors and light receivers are not operating normally, hole defect detection cannot be performed accurately, but until now, those equipped with a function to diagnose the light projectors and light receivers Not proposed.

JP-A-1-320455

  The subject of this invention is providing the hole defect detection apparatus of the steel strip which has a diagnostic function of a light projector and a light receiver.

In order to solve the above-mentioned problems, a hole defect detection device for a steel strip according to the present invention has a projector and a light receiver arranged above and below the steel strip that is continuously conveyed, and the hole defect in the steel strip that comes out of the projector A hole defect detecting device for detecting a hole defect in a steel strip by receiving light passing therethrough with a light receiver, characterized by having the following configurations (1) to (4).
(1) The projector includes a diagnostic photodetector installed at a position away from the projection opening toward the steel strip, and directs light spreading in the width direction of the steel strip to the projection aperture and transmits the light. And an optical system having a part directed to the diagnostic photodetector.
(2) The light receiver includes a diagnostic light source and an optical system that irradiates diagnostic light from the light source toward a photodetector that detects light from the projector.

(3) A projector diagnosis unit that diagnoses the projector based on a light detection signal from a diagnostic photodetector of the projector.
(4) Almost simultaneously with the timing at which a hole provided in the weld between the coils of the steel strip is detected as a hole defect, the hole passes over the light receiving port, and the weld is over the light receiving port. A receiver diagnostic unit for diagnosing the light receiver based on a light detection signal from the light detector of the light receiver by making diagnostic light incident on the light detector of the light receiver by the optical system at a timing predicted to exist; Have.

  The hole defect detection device of the present invention is used by irradiating light from a projector toward the steel strip while the steel strip is continuously conveyed. At that time, if light is emitted from the projector toward the steel strip, the optical detector for diagnosis of the projector continues to detect light by the optical system, and therefore the projector is determined to be normal by the projector diagnostic unit. If no light is emitted from the projector toward the steel strip, the diagnostic light detector of the projector does not detect the light, and the projector diagnosis unit determines that the projector is abnormal.

  The diagnosis of the light receiver is performed by causing the light receiver diagnosis unit to enter the diagnostic light into the light detector of the light receiver by the optical system at a certain timing. The timing is almost the same as the timing at which the hole provided in the weld between the coils of the steel strip is detected as a hole defect, or the hole passes over the light receiving port and the weld is over the light receiving port. It is the timing that is predicted to exist. That is, in the hole defect detection device of the present invention, the light receiver diagnosis is performed at the welded portion of the steel strip.

  During the hole defect detection, the light from the projector is detected by the photodetector of the light receiver at the portion where the steel strip has a hole defect. If the diagnostic light is incident on the photodetector of the receiver while detecting the hole defect, the light detection by the photodetector of the receiver receives both the light from the projector and the diagnostic light due to the presence of the hole defect. It is impossible to distinguish whether it is due to the fact that it is due to the fact that it is due to the fact that it is due to the fact that it has been received or only the diagnostic light is received without the presence of a hole defect. Therefore, in the portion of the steel strip where the light receiver diagnosis is performed, it may be determined that the hole defect is detected even if there is no hole defect, and the hole defect detection is not performed accurately.

  In the hole defect detection device of the present invention, the light receiver diagnosis is performed at the welded portion of the steel strip. Since the welded portion, which is the joint between the steel strip coils, is a portion that is discarded as a product at the time of shipment, there is no problem even if the hole defect is not accurately detected. Thereby, the light receiver can be diagnosed while accurately detecting a hole defect in the entire portion of the steel strip.

  According to the hole defect detection device for a steel strip of the present invention, it is possible to diagnose the light projector and the light receiver constituting the hole defect detection device while accurately detecting the hole defect in the entire portion of the steel strip product. it can.

It is a schematic block diagram which shows the hole defect detection apparatus of the steel strip corresponded to one Embodiment of this invention. It is a perspective view which shows arrangement | positioning of the light projector and light receiver which comprise the hole defect detection apparatus of embodiment. It is the front view (a) and side view (b) which show the optical system of a light projector. It is a perspective view which shows the optical system of a light receiver. It is a flowchart which shows the arithmetic processing which the optical receiver diagnostic part of the hole defect detection control apparatus which comprises the hole defect detection apparatus of embodiment implements. FIG. 6 is a time chart based on the flowchart of FIG. 5, when diagnosis of all the light receivers is performed almost simultaneously with the timing at which the weld hole of the steel strip is detected as a hole defect, and when the weld hole is at the light receiving port. A case (b) in which all the light receivers are diagnosed at a timing of passing through a downstream position by Lm is shown.

Embodiments of the present invention will be described below.
As shown in FIG. 1, the steel strip hole defect detection apparatus of this embodiment has a projector 2 and a light receiver 3 arranged above and below the steel strip 1 that is continuously conveyed, and a little upstream of these. The welding hole detector 5, the tracking device 6, the hole defect detection control device 7, and the display device 8 are arranged.
The steel strip 1 is continuously conveyed by connecting a plurality of coils by welding, and a hole for tracking (hereinafter referred to as a “welded hole”) is provided in a welded portion between the coils.

As shown in FIG. 2, the light projector 2 and the light receiver 3 have a large number of moving directions of the steel strip 1 along the width direction of the steel strip 1 so that hole defects can be detected without leakage in the entire width direction of the steel strip 1. Are installed in a staggered arrangement in two rows.
As shown in FIG. 3, the optical system of the projector 2 includes a laser oscillator 21, a polygon mirror 22, a beam splitter 23, a plate mirror 24, and two diagnostic photodetectors 25. The laser beam 210 output from the laser oscillator 21 is reflected by the rotating polygon mirror 22 and spreads in the width direction of the steel strip 1, travels downward, and enters the beam splitter 23.

  The laser beam 210 that has entered the beam splitter 23 is divided into light 211 that is directed to the elongated projection port 20 provided below the projector 2 and light 212 that is directed to the plate-like mirror 24. The laser beam 212 that has been directed is reflected by the plate-like mirror 24 and enters the diagnostic photodetector 25. The two diagnostic photodetectors 25 are arranged at both ends of the laser beam 212 in the width direction and surely enter the range of the laser beam 212. The diagnostic photodetector 25 outputs the light detection signal A1 to the hole defect detection control device 7.

  As shown in FIG. 4, the light receiver 3 includes an elongated light receiving port 30, a laser oscillator 31, a right-angle reflecting prism 32, a plano-concave cylindrical lens 33, and a light detector 34 that are aligned with the light projecting port 20 of the light projector 2. It consists of. The laser oscillator 31, the right-angle reflecting prism 32, and the plano-concave cylindrical lens 33 are disposed obliquely above the upper surface of the photodetector 34. The laser oscillator 31 and the right-angle reflecting prism 32 are arranged at the same height. The laser beam 310 output from the laser oscillator 31 changes its direction by 90 ° by the right-angle reflecting prism 32, spreads by the plano-concave cylindrical lens 33, and is received by the photodetector 34.

  The size of the photodetector 34 is substantially the same as that of the elongated light receiving port 30, and the light detector 34 is disposed directly below the light receiving port 30. The light projector 2 and the light receiver 3 are installed such that the light projecting port 20 and the light receiving port 30 are aligned. Therefore, the photodetector 34 of the light receiver 3 can receive the laser beam 211 (only the optical axis is displayed in FIG. 4) that is emitted from the projector 2 and spreads in the width direction of the steel strip 1. Further, the photodetector 34 outputs a light detection signal A2 to the hole defect detection control device 7.

The weld hole detector 5 detects that the weld hole of the steel strip 1 has reached a slightly upstream side of the position where the projector 2 and the light receiver 3 are arranged, and sends the weld hole approach signal A3 to the tracking device 6 and the hole. Output to the defect detection control device 7.
The tracking device 6 constantly monitors the steel strip 1 and outputs a tracking signal A4 indicating the progress of the steel strip 1 to the hole defect detection control device 7.

The hole defect detection control device 7 diagnoses the hole defect detection unit 71 that always detects whether or not the steel strip 1 has a hole defect, the projector diagnosis unit 72 that always diagnoses the projector 2, and the light receiver 3 at a predetermined timing. And a photoreceiver diagnosis unit 73.
The hole defect detection unit 71 outputs a hole defect detection signal B1 indicating whether or not a hole defect has occurred in the steel strip 1 to the display device 8 based on the light detection signal A2 from the light detector 34 of the light receiver 3. .

The projector diagnostic unit 72 outputs a projector diagnostic signal B2 indicating a diagnostic result of the projector 2 to the display device 8 based on the light detection signal A1 from the diagnostic photodetector 25 of the projector 2.
The light receiver diagnosis unit 73 is based on the light detection signal A2 from the light detector 34 of the light receiver 3, the weld hole approach signal A3 from the weld hole detector 5, and the tracking signal A4 from the tracking device 6. An arithmetic processing according to the flowchart shown in FIG.

The flowchart of FIG. 5 will be described.
First, in step S1, it is determined whether or not the welding hole approach signal A3 from the welding hole detector 5 has been received, and if received, the process proceeds to step S2 to track the welding hole in preparation for the start of diagnosis of the optical receiver. To start.
Next, the process proceeds to step S3, where the welding hole passes a position downstream of Lm of the light receiving port 30 (the center of the welding hole passes over the light receiving port 30, and the welded portion exists on the light receiving port 30). It is determined whether or not the timing is predicted. This timing is predicted by calculating the feed amount of the steel strip 1 after passing through the weld hole detector 5 based on the tracking signal A4 input from the tracking device 6. If it is not the timing, the process proceeds to step S4. If it is, the process proceeds to step S5.

In step S4, it is determined whether or not a hole defect is detected by the hole defect detector 71. When a hole defect is detected (that is, when a weld hole is detected as a hole defect), the process proceeds to step S6, and when it is not detected, the process returns to step S3.
When the process proceeds from step S3 to step S5, the laser beam 211 that has passed through the welding hole cannot be received by any of the photodetectors 34. Therefore, in step S5, any one of the photodetectors 3 or the projectors 2 is detected. After a signal indicating that there is an abnormality is output as the receiver diagnostic signal B3, the process proceeds to step S6.

In step S6, start signals are output to the laser oscillators 31 of all the light receivers 3, all the laser oscillators 31 are started, the diagnostic laser beam 310 is incident on the photodetectors 34, and all the light receivers 3 are activated. After the light detector 34 is diagnosed, the process proceeds to step S7. In step S7, it is checked whether diagnostic light has been received for all the photodetectors 34, and the process proceeds to step S8.
In step S8, it is determined whether diagnostic light has been received by all the photodetectors 34, or diagnostic light has not been received by any of the photodetectors 34, and diagnostic light has been received by all the photodetectors 34 Proceeds to step S9. In step S9, a signal indicating that all the light receivers 3 are normal is output as the light receiver diagnostic signal B3, and then the calculation process is terminated.

If any of the photodetectors 34 cannot receive the diagnostic light, the process proceeds from step S8 to step S10, and a signal indicating the number of the photodetector 3 that cannot be received by the photodetector 34 is received. After outputting as the diagnostic signal B3, the arithmetic processing is terminated.
The display device 8 displays the detection results of the hole defects and the diagnosis results of the projector 1 and the light receiver 2 based on the signals B1 to B3 from the hole defect detection control device 7.

The steel strip hole defect detection apparatus of this embodiment operates as follows.
While the steel strip 1 is moving, the laser oscillator 21 of the projector 2 is always operated, and a laser beam 211 that is wide and directed downward is irradiated onto the upper surface of the steel strip 1 and reflected by the plate mirror 24. 212 enters the diagnostic photodetector 25.
When there is no abnormality in the projector 2, the diagnostic photodetector 25 of the projector 2 receives the laser beam 212, and a light detection signal A 1 indicating this is input to the projector diagnostic unit 72, and the projector diagnostic unit 72 displays the display device 8. In addition, a projector diagnostic signal B2 indicating a diagnosis result indicating that the projector 2 is normal is output. When there is an abnormality in the projector 2, the diagnostic light detector 25 of the projector 2 does not receive the laser light 212, and a light detection signal A 1 indicating this is input to the projector diagnostic unit 72, and the display device is displayed from the projector diagnostic unit 72. 8, a projector diagnostic signal B2 indicating a diagnostic result indicating that the projector 2 is abnormal is output. Then, the diagnosis result of the projector 2 is displayed on the display device 8.

  When the portion where the hole defect of the steel strip 1 is generated passes directly under the projector 2, the light detector 34 of the light receiver 3 receives the laser light 211 from the light projector 2, and indicates the light from the light detector 34 indicating this. The detection signal A <b> 2 is input to the hole defect detection unit 71 of the hole defect detection control device 7. Along with this, a hole defect detection signal B1 indicating that a hole defect has occurred in the steel strip 1 is output from the hole defect detection unit 71 to the display device 8, and the display device 8 indicates that a hole defect has occurred. Is displayed.

  Further, when the weld hole detector 5 detects the weld hole of the steel strip 1 and the weld hole approach signal A3 is input to the light receiver diagnosis unit 73, the process proceeds from step S1 to step S2 in the flowchart of FIG. The tracking of the weld hole is started. Then, when it is determined in step S3 that the welding hole of the steel strip 1 is predicted to pass through a position downstream by Lm of the light receiving port 30, or in step S4, the hole defect detection unit 71 detects the welding hole. When the hole defect is detected, the light receiver 3 is diagnosed in steps S6 and S7.

  That is, when the welding hole of the steel strip 1 reaches the light receiving port 30 of the light receiver 3, the laser light 211 emitted from the light projector 2 is received by the photodetector 34 of the light receiver 3, thereby When the defect detection unit 71 detects a weld hole as a hole defect, at this time, the laser oscillators 31 of all the light receivers 3 are activated and the diagnostic laser beam 310 is incident on the photodetector 34 ( Step S6).

  On the other hand, when the weld hole of the steel strip 1 reaches the light receiving port 30 of the light receiver 3, the laser light 211 emitted from the projector 2 is not received by the light detector 34 of the light receiver 3, and the hole defect is detected. If the weld hole is not detected as a hole defect in the portion 71, when it is determined in step S3 that it is predicted that the weld hole will pass through a position downstream by Lm of the light receiving port 30, step S5 is performed. Thus, a light receiver diagnostic signal B3 indicating that any one of the light receivers 3 or the projectors 2 is abnormal is output to the display device 8. Thereafter, the laser oscillators 31 of all the light receivers 3 are activated, and the diagnostic laser beam 310 is incident on the photodetector 34 (step S6).

Next, based on the light detection signal A2 output from the light detector 34 of each light receiver 3, it is confirmed whether or not the light detector 34 of each light receiver 3 has received the diagnostic laser beam 310 ( In step S7), when light reception is confirmed by all the photodetectors 34, the process proceeds from step S8 to step S9, and the light receiver diagnostic signal B3 indicating that all the light receivers 3 are normal is displayed on the display device 8. And the display device 8 displays that all the light receivers 3 are normal. In this case, since there is an abnormality in the projector 2 instead of the light receiver 3, the signal output in step S5 may be changed.
If no photodetection is confirmed by any of the photodetectors 34, the process proceeds from step S8 to step S10 to determine which photoreceiver 3 is abnormal (the photoreceiver that could not receive light by the photodetector 34) 3 is output to the display device 8, and the number of the light receiver 3 that is abnormal is displayed on the display device 8.

The time chart of FIG. 6A shows a case where the process proceeds from step S3 to step S4 to step S6 in the flowchart of FIG. That is, a case is shown in which the light receiver 3 directly under the weld hole is normal and all the light receivers 3 are diagnosed almost simultaneously with the timing at which the weld hole of the steel strip 1 is detected as a hole defect.
The time chart of FIG. 6B shows a case where the process proceeds from step S3 to step S5 to step S6 in the flowchart of FIG. That is, the light receiver 3 directly below the weld hole or the projector 2 directly above the weld hole is abnormal, and the weld hole passes through a position downstream by Lm of the light receiving port 30 (the welded portion having a length Lm from the weld hole is A case where all the light receivers 3 are diagnosed at a timing (existing on the light receiving port 30) is shown.

In the hole defect detection device of this embodiment, at the time of diagnosis of the light receiver 3, whether the light detection by the light detector 34 is only by receiving diagnostic light or includes light reception from the projector 2 due to the presence of hole defects Therefore, accurate hole defect detection cannot be performed. However, the diagnosis of the light receiver 3 is performed at the welded portion of the steel strip 1, which is a portion discarded as a product at the time of shipment.
Therefore, according to the hole defect detection device of this embodiment, the light receiver 3 can be diagnosed while accurately detecting the hole defect in the entire portion of the steel strip 1 as a product.

DESCRIPTION OF SYMBOLS 1 Steel strip 2 Projector 20 Projector 21 Laser oscillator 210 Laser light 211 Light directed downward 212 Light directed to plate mirror 22 Polygon mirror 23 Beam splitter 24 Plate mirror 25 Diagnostic light detector 3 Light receiver 30 Light receiver DESCRIPTION OF SYMBOLS 31 Laser oscillator 32 Right angle reflecting prism 33 Plano-concave cylindrical lens 34 Photo detector 310 Laser beam for diagnosis 5 Weld hole detector 6 Tracking apparatus 7 Hole defect detection control apparatus 71 Hole defect detection part 72 Projector diagnosis part 73 Light receiver diagnosis part 73 8 display devices

Claims (1)

A projector and a light receiver are placed above and below the steel strip that is continuously conveyed, and the hole defect in the steel strip is detected by receiving the light that has passed through the hole defect in the steel strip from the projector. A hole defect detection device,
The projector includes a diagnostic photodetector installed at a position away from the projection opening toward the steel strip, and directs light spreading in the width direction of the steel strip to the projection aperture and a part of the light. An optical system directed to the diagnostic photodetector,
The light receiver includes a diagnostic light source and an optical system that irradiates diagnostic light from the light source toward a photodetector that detects light from the projector,
A projector diagnostic unit for diagnosing the projector based on a light detection signal from a diagnostic photodetector of the projector;
Predicted that the hole provided in the weld between the coils of the steel strip is almost simultaneously with the timing at which the hole is detected as a hole defect, or that the hole passes over the light receiving port and the weld exists on the light receiving port. And a light receiver diagnostic unit for diagnosing the light receiver on the basis of the light detection signal from the light detector of the light receiver by making the diagnostic light incident on the light detector of the light receiver by the optical system at the timing. Steel strip hole defect detection device.

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