JP3201296B2 - Diagnosis method for metal material defect detection device and defect spark simulated light source - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention diagnoses the degree of adhesion of dust and the like generated in a device for detecting a defect of a metal intermediate material, especially a steel slab during fusing, to an optical system, and the aging of a measurement control system. The present invention relates to a method of diagnosing an apparatus for detecting a defect of a metal material and a simulated light source for a defective spark used in the method.

[0002]

2. Description of the Related Art In the production of metal materials, particularly steel materials,
Determining the necessity of maintenance and the degree of maintenance, such as cutting, by detecting defects such as curling, pinholes, sand scum, etc., existing in the steel slab in the cold or high temperature state before hot rolling. Inspections are performed to grade the materials. This inspection is performed by a method of imaging and quantifying a defective spark generated when there is a defect during a predetermined amount of cutting.

[0003] Since the defect detection apparatus used in this inspection is used in an environment with water vapor, dust, vibration, high temperature, etc., even when the detection apparatus is initially set in an appropriate state, it may become optically aging over time. Obstacles to the system etc. will accumulate. In such a case, there is a problem that it is not easy to judge whether dust is simply attached to the camera or whether an aging factor inherent in the detection device, for example, a vacuum tube or the like (mainly an imaging tube) is deteriorated.

[0004] Generally, the causes of malfunctions of the defect detection device are roughly classified into the following three points.

[0005] Malfunction of the utility supplied to the ablation apparatus (such as a decrease in the pressure of the ablation gas) and clogging of the nozzle for jetting the ablation gas cause "malfunction of the ablation". In this case, the defective spark does not clearly appear optically, or a luminance variation very similar to the defective spark appears on the molten pool. In this case, repair is not required for the defective spark detector,
A diagnosis that the cutting device requires repair adjustment work must be derived.

[0006] In order to observe the molten pool in a bad environment in which metal material is abraded, dirt adheres to a light receiving device such as a television camera, and mist-like water droplets and fine powders are formed on the optical path from the molten pool to the light receiving device. "Failure in optical system" where flying or other objects that block the optical path fly.

[0007] Radiation from the molten pool causes a light-receiving device such as a television camera to become hot and output an abnormal signal, noise from the device to be mixed into a signal line, or an abnormality in an electric circuit or the like for processing an output signal. "Failure in the light receiving device and signal processing device" such that defective sparks cannot be detected properly.

The following methods have been proposed so far for diagnosing the degree of malfunction of the defect detection device caused by the above-mentioned causes.

One of the methods is to continuously observe the brightness distribution of the image of the molten pool online over time during the steady production of metal materials and to compare the deviation from the initial normal state ( JP-A-6-229946). According to this method, it is possible to detect disturbance caused by water vapor during operation of the defect detection device, contamination of the lens, deviation of the field of view of the imaging camera, abnormality caused as a result of malfunction of the signal differential processing circuit, and the like.

However, this method is mainly for on-line diagnosis during operation, and has a problem that it is not rigorous because it is affected by a steel slab temperature, a steel type and the like during operation. In addition, sparks caused by inclusions, which are natural defects,
Once ablation is performed once for spark detection, it is lost and cannot be reproduced under the same conditions, and cannot be used repeatedly for diagnosis until the cause of the malfunction is clearly identified.

As another method, a method has been proposed in which an artificial defect (drill hole) is provided in a steel slab, and a defect spark is generated by cutting the hole, thereby diagnosing the capability of the apparatus. JP-A-7-120409). According to this method, since a defect is prepared in advance, highly reliable diagnosis is possible.

However, in this method, it is necessary to prepare a metal material, form a drill hole in the metal material, and cut and drill it. Unlike the method of online monitoring of actual production described above, in the case of hot inspection, such a diagnostic method involves heating a steel slab after drilling at a high temperature and collecting diagnostic data of the device during cutting. In some cases, the actual manufacturing process may be disturbed by repeating the above operation. In the production of steel materials adopting the mass production method, the influence on the subsequent processes is enormous, especially at the stage immediately before the start of the hot rolling process. In cold inspections, the situation that the next hot rolling process is waiting for steel slabs is the same as hot inspections, and is common in that stable and accurate inspection and repair are required constantly. are doing.

If the diagnosis is not carried out on the actual production line, it is necessary to spend a large amount of time on a large apparatus for handling the steel slab, for example, slab heating for reproducing the hot inspection. Regardless of whether cold inspection or hot inspection,
The cost of steel slabs cannot be ignored. Further, in order to clarify whether the cause of the malfunction is a malfunction of the abrasion (the above-mentioned cause) or a malfunction (cause) after the optical system, a diagnosis by a method without the abrasion is required. I was

[0014]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a method of diagnosing a defect detecting device for a metal material, particularly a steel material, without fusing, and a simulated light source for a defective spark used in the method.

[0015]

SUMMARY OF THE INVENTION The present inventors have determined that a method for replacing a defective spark generated at the time of cutting with an optically equivalent one is very desirable from the following circumstances.

A) If the expected result cannot be obtained by a single diagnosis and adjustment of the defect detection device, the re-diagnosis is repeated, so that a simple method without fusing is required.

(B) When judging a malfunction that continues after the cause of the malfunction, such as a malfunction due to adhesion of dirt, it is not necessary to perform ablation of a metal material having an artificial defect therein, and an optically equivalent light source , And confirm that the light from the light source reaches the camera normally.

C) For the purpose of periodic diagnosis, it is only necessary to provide a light source having only the features of the defective spark which are used for detection by the defect detection device.

However, when diagnosing using a simulated defective spark light source without using fusing, there are the following problems to be overcome.

When diagnosing the apparatus by imaging a defective spark or the like during cutting, the luminance of the defective spark or the like is extremely high.
Usually, the camera is provided with an optical filter for reducing the luminance to about one ten-thousandth. The sensitivity of the imager with the optical filter attached is very low, and nothing appears on the imager without fusing. For this reason, when trying to diagnose the imaging device by photographing an object having a lower luminance than a defective spark or the like, the imaging device stored in the camera case is taken out of the camera case to remove dust, and the optical filter is removed. You have to take the method of putting it in the camera case again. At this time, when the imaging device is taken out of the camera case in order to reattach the optical filter that has been removed after being diagnosed by imaging, there is a problem that the direction of the camera that has been diagnosed changes. For the above reasons, no diagnosis of the defect detection apparatus using the defect spark simulated light source was actually performed.

The present inventors have conducted various tests on a simulated defective spark light source and found that the above problem can be solved by using an appropriate simulated defective spark light source.

The present invention has been completed by repeatedly examining a defective spark simulated light source and repeating a test for monitoring a defective spark simulated light source by a defect detecting device having an abnormality at a metal material manufacturing site. The gist of the present invention is a method of diagnosing a detection device and a simulated defective spark light source used in the method.

(1) A diagnostic method for an apparatus for detecting a defect in a metal material by imaging a molten pool formed when the surface layer of the metal material is ablated and a defect spark generated from a defect in the molten pool. Then, the defective spark simulated light source is disposed near the optically same position as the position where the molten pool occurs at the time of imaging as viewed from the imaging system of the device, and the light source is imaged by the device, and the relative or absolute A method for diagnosing a defect detecting device for a metal material that diagnoses the device by evaluating a target luminance distribution (referred to as [Invention 1]).

(2) A light source provided with a light bulb 8 and a black body furnace 10, wherein a filament in the light bulb is a defective spark.
A simulated defective spark light source (referred to as [Invention 2]) used in the diagnostic method according to [Invention 1], wherein the blackbody furnace is configured to be imaged as a molten pool.

(3) A laser generator 12 serving as a light beam supply source of an optical system, an optical system for forming light that simulates a molten pool formed in a metal material during fusing, and a light for simulating a defect spark generated from a defect. The diagnosis according to [Invention 1], wherein each of the optical systems is set so that light formed by each optical system is captured as a molten pool and a defective spark, respectively. A defective spark simulated light source used in the method (referred to as [Invention 3]).

In the above [Invention 1] to [Invention 3],
The “defective spark simulated light source” refers to the following light sources (a), (b) or (c) according to the monitoring method of the defect detection device.

(A) In a device for detecting a defect in a metal material by monitoring a defective spark, a light source having a luminance substantially equal to that of the defective spark.

(B) In a device for detecting a defect in a metal material by monitoring a difference in luminance between a defective spark and a molten pool, a light source having a luminance substantially equal to the luminance difference between the defective spark and the molten pool.

(C) In an apparatus for detecting a defect in a metal material by monitoring the luminance of both the defective spark and the molten pool, a light source having the same luminance as that of the defective spark and the same luminance as the molten pool are obtained. Have both light sources.

In [Invention 1], the "diagnosis" means not only determining the necessity of the repair work before the repair work, but also determining whether the repair work is necessary after the repair work and the calibration, and This includes confirmation of initial performance limits. Note that it is preferable that the calibration of the defective spark simulated light source for associating the size of the defective spark generated from the artificial defect having a predetermined size with the luminance of the defective spark simulated light source be performed as a preliminary operation before performing the diagnosis. "Metal material" corresponds to an intermediate material of metal, particularly a steel slab.

The "luminance distribution" refers to the distribution of light sources on an image, and includes the case where only "luminance" is evaluated without regard to "distribution".

"Near the same position" means the same position and a close position. This is because a defective spark is generated from an arbitrary position in the molten pool during actual cutting, and a definite position cannot be specified for the defective spark. [Invention 2]
In the above, in a strict sense, the blackbody furnace and the bulb cannot be arranged at the same position, but in practice, the object can be achieved by arranging them close to each other. "Light bulb" refers to a transparent light bulb.

"Position as viewed from the imaging system" refers to a position optically in the same direction and at the same distance as viewed from the camera of the imaging system.

"Imaging" means capturing a molten pool and a defective spark as an image.

[Invention 2] and [Invention 3] belong to the category of the light source (c). The light source used in [Invention 1] is not limited to the light source in [Invention 2] or [Invention 3].

[0036]

Next, the reason why the present invention is set as described above will be described. First, the defective spark simulated light source ([Invention 2] and [Invention 3]) will be described, and then the diagnostic method ([Invention 1]) will be described.

1. FIG. 1 shows a light source having the same luminance as the defective spark and a light source having the same luminance as the molten pool in the actual imaging system. It is the schematic diagram arrange | positioned in the same position as the time of cutting. A blackbody furnace 10 is arranged at a place where a molten pool is generated, and before that, a bulb 8 is arranged close to the blackbody furnace so that a filament in the bulb simulates a defective spark.

[0038] Since the defective spark is generated in contact with the molten pool,
The light bulb is brought as close as possible to the black body furnace, but it is desirable to provide an air curtain 9 in order to prevent the light bulb 8 from being heated by hot air from the black body furnace. If the opening window of the black body furnace is sufficiently large, the black body furnace may be moved away. If the temperature of the black body furnace 10 is set to be the same as the temperature of the molten pool,
The amount of light reaching the camera 1 is reduced due to reflection on the inner and outer surfaces of the glass of the light bulb 8. However, bulb 8
It is not necessary to perform antireflection treatment on the inner and outer surfaces of the glass. The temperature of the black body furnace 10 may be set slightly higher so as to output a signal of the same intensity level as when the molten pool was photographed. This set temperature is based on prior calibration.

The light source does not necessarily need to be arranged at the same position where the molten pool occurs.

FIG. 2 shows a configuration in which the observation window of the blackbody furnace can be arranged on the side surface in order to solve the case where the arrangement shown in FIG. As shown in FIG. 2, the observation window of the black body furnace may be arranged on the side surface if the optical equivalence is maintained by using the reflecting mirror 11 or the like. In this case, if the radiation from the filament of the light bulb 8 is almost the same as that of the defective spark, the amount of light reaching the camera 1 decreases due to absorption by the reflecting mirror 11, but as a countermeasure, it is necessary to perform special processing on the reflecting mirror 11. There is no. The temperature of the light bulb 8 may be set slightly higher so as to output a signal of the same intensity level as when the defective spark was photographed. This set temperature is based on prior calibration. Other optical means such as a prism other than the reflecting mirror 11 may be used. In addition, when there is a problem in adjusting the distance of the light source to the actual distance, the diagnosis may be performed by performing a modification as shown in FIG. 2 with respect to FIG.

At a voltage equal to the rated voltage of the bulb, 3000
Since the temperature becomes about k, the lamp is first lit by applying a lower voltage, and then the filament temperature is measured using an optical pyrometer to adjust the voltage to set an appropriate temperature.

[Invention 3] uses a laser as a light source.

FIG. 3 shows a defective spark simulated light source using a laser. The laser light emitted from the laser 12 is split into two directions by a beam splitter 13. One is
The light is reduced to an appropriate light flux by the neutral density filter 16, the beam diameter is widened by the collimator 15, and guided to the reflecting mirror 13 to enter the camera. This part is an optical system that functions to simulate a molten pool. The other is an optical system that simulates a defective spark. The light emitted from the laser is reduced to an appropriate light flux by the neutral density filter 16, the beam is expanded linearly by the prism 14, and is expanded by the concave lens 17 like light from a defective spark and adjusted to have a finite brightness. The beam is split into the camera 1 by the beam splitter 13 together with the beam simulating the molten pool.

As the laser generator, for example, the brightness of the molten pool is 10 ⁶ cd / mm ² , the area of the imaging surface is 10 ⁻⁴ m ² ,
Solid angle of exit pupil 10 ^-2 steradians, laser wavelength 63
Considering that the relative luminous efficiency is 0.25 under the condition of 3 nm, an output of 6 mW is sufficient for an ideal optical system, and a He-Ne laser having such an output can be used.

2. Diagnosis Method ([Invention 1]) Calibration work of associating a defective spark simulated light source with an actual defective spark, which should be performed in advance before diagnosing the defect detection device, is performed as follows. The defect detection device used at this time must be in a normal state.

Artificial defects having various diameters and depths are formed on the surface of the metal material. The artificial defect may be a drill hole, the drill hole may be filled with a substance simulating an inclusion such as sand, or the artificial hole may be covered by welding or the like. The type of spark generated by fusing the upper portion is photographed with an imaging device and quantified. Next, by adjusting the defective spark simulated light source according to the present invention, light sources having various thicknesses and brightnesses are realized, and the thicknesses and brightnesses imaged in the same manner as the sparks are associated.
If these light sources are configured so as to be easily attached and detached to a fixed position, the direction and focus can be accurately adjusted. Once such adjustments have been made, the light source described in the present invention may be used for subsequent diagnosis of the defect detection device.

Specific conditions for the defect spark simulated light source are set as follows.

The temperature of the molten pool slightly varies depending on the cutting conditions, but in order to simulate the temperature difference, the temperature of the black body furnace 10 must be changed as it is in the arrangement of FIG. 1 or FIG. Can be realized by: In the arrangement of FIG.
The temperature change of the molten pool is measured by the collimator 15 or the neutral density filter 1.
6 can be realized.

The type and size of the defect in the metal material, or
The brightness of the defective spark varies variously depending on the cutting conditions such as the blowing speed of the cutting flame. In order to achieve different brightness of the defective spark, the brightness of the filament is controlled by controlling the voltage, current, power, etc. supplied to the bulb 8. When a laser is used, it can be realized by adjusting the arrangement of the prism 14 and the neutral density filter 16.

FIG. 4 is a schematic view of a defective spark generated from a molten pool generated by actual ablation. FIG.
In FIG. 2, it is observed that a spark 19 originating from the defect is generated in the direction of the cutting flame in the molten pool 18.

FIG. 5 shows the luminance measured along the scanning line AA 'in FIG. Defective spark 19 in the gentle molten pool
Is detected as a high-luminance part.

FIG. 6 shows that this signal is used to detect a defective spark whose luminance is insufficient compared with the luminance of the molten pool.
This is a signal that has been subjected to differential processing by a C circuit or the like.

The defect spark has various thicknesses depending on the blowing speed of the cutting flame, other cutting conditions, the type and size of the defect, and the like.

FIG. 7 is an image obtained by observing the filament of the bulb 8 in the manner shown in FIG. 1 or FIG. When the filament 20 of the light bulb 8 is imaged as shown in FIG.
And CC ′ differ in the length of the filament traversed by the scanning line.

FIG. 8 shows the luminance along the scanning line BB 'in FIG.

FIG. 9 shows a signal obtained by differentiating the signal. Similarly, a signal having a narrow interval between high-luminance portions is a scanning line C.
It is obtained by signal processing along C '. As described above, if the filament forms an appropriate curve and the scanning line is continuously changed with respect to the curve, it is possible to capture a spark having a wide range with a single image. Become.

FIG. 10 is an image of a linear light source simulating a defective spark of the type shown in FIG. 3 using a laser. FIG. 11 shows this image rotated using a prism to change the direction of the simulated spark. Obtaining an image obtained by rotating FIG. 10 as shown in FIG. 11 and diagnosing based on the image correspond to changing the thickness of the spark.

FIG. 12 shows an arrangement in which the width of the prism is changed by adjusting the arrangement of the prisms. The fact that the width can be freely changed is a feature of the defective spark simulated light source.

FIG. 13 shows a line in which the width is continuously changed by adjusting the arrangement of the prisms.

In the diagnosis, the direction of the camera of the imaging system, the angle of view, the focus, the aperture, the amount of incident light, and the like are checked.

The light source for simulating the defective spark in [Invention 1] is not limited to the light source specified in [Invention 2] or [Invention 3], and another linear light source may be used instead of the light bulb.
If the spark detection method is a method that does not use the fact that the spark is linear, it does not need to be a line light source. As a light source simulating a molten pool, another surface light source may be used instead of the black body furnace. If the spark detection method does not use the fact that the molten pool is planar, it may not be a surface light source.

In the case where the spark detection method of the defect inspection apparatus is a method in which detection is performed based on only the brightness of the spark and does not depend on the brightness of the molten pool (in the case of the defective spark simulated light source (a)),
In [Invention 2], the black body furnace 10 is omitted.

When the spark detection method is based on the difference in brightness between the spark and the molten pool (in the case of the defective spark simulated light source (b)) and does not depend on the absolute value of the brightness, the light bulb 8
May be omitted so that the brightness of the blackbody furnace 10 is equal to the brightness difference between the spark and the molten pool. However, in this method, it is necessary to check whether or not the camera 1 is saturated when a defective spark is actually photographed. Therefore, the luminance of the bulb 8 can be set to be the same as the luminance of the defective spark. It is checked whether the camera 1 is saturated with the same brightness as the brightness of the defective spark.

The same applies to [Invention 3], in which one of the two optical systems is omitted.

[0065]

According to the present invention, diagnosis can be performed simply and quickly based on a simulated spark light source without fusing, thereby improving the efficiency of diagnosis. As a result, re-diagnosis after adjustment once can be repeated quickly, which leads to an improvement in the accuracy of the defect detection device, leading to an improvement in quality and productivity in metal material production.

[Brief description of the drawings]

FIG. 1 is a simulated defective spark light source according to [Invention 2].

FIG. 2 is a defect spark simulated light source according to [Invention 2] (an example using a reflecting mirror).

FIG. 3 is a simulated defective spark light source according to [Invention 3].

Fig. 4 Image of cutting flame, molten pool, defective spark

FIG. 5 is a waveform diagram of a luminance signal on an AA ′ scanning line in FIG. 4;

6 is a signal waveform obtained by differentiating the luminance signal waveform of FIG. 5 by an RC circuit.

FIG. 7 is an image of the filament of [Invention 2].

8 is a waveform diagram of a luminance signal on a BB ′ scanning line in FIG. 7;

9 is a signal waveform obtained by differentiating the luminance signal waveform of FIG. 8 by an RC circuit.

FIG. 10 is an image of a defective spark simulated light source according to [Invention 3].

11 is an image obtained by tilting the image of FIG. 10 by rotating a prism.

FIG. 12 shows an image obtained by changing the width of the image shown in FIG. 10 by adjusting a prism.

FIG. 13 is an image in which the width of the image in FIG. 10 is continuously changed by adjusting a prism.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Camera 2 ... Lens 3 ... Dim filter 4 ... Camera case 5 ... Camera case front glass 6 ... Easy replacement glass for blocking the adhering matter to the camera case front glass 5 7 ... Soot to glass 5 and glass 6 Air purge for blocking adhesion 8 ... Light bulb 9 ... Air curtain 10 ... Black body furnace 11 ... Reflection mirror 12 ... Laser generator 13 ... Reflection mirror 14 ... Prism 15 ... Collimator lens 16 ... Dimming filter 17 ... Concave lens 18 ... Molten pool 19 ... Image of defective spark 20 ... Signal image of bulb filament 21 ... Image of defective spark simulated light source (laser light source) of [Invention 3]

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-59-154346 (JP, A) JP-A-59-174275 (JP, A) JP-A-5-87745 (JP, A) 229946 (JP, A) JP-A-7-120409 (JP, A) JP-A-8-338813 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G01N 21/88-21 / 894 B23K 31/00

Claims (3)

(57) [Claims] A diagnostic method for an apparatus for detecting a defect in a metal material by imaging a molten pool formed when a surface portion of a metal material is ablated and a defect spark generated from a defect in the molten pool. The defective spark simulated light source is disposed near the optically same position as the position where a molten pool occurs at the time of imaging when viewed from the imaging system of the device, and the light source is imaged by the device, and the relative or absolute A method for diagnosing a defect detecting device for a metal material, wherein the device is diagnosed by evaluating a luminance distribution. 2. A light source comprising a light bulb (8) and a black body furnace (10), wherein the filament in the light bulb is imaged as a defective spark and the black body furnace is imaged as a molten pool. A simulated defective spark light source used in the diagnostic method according to claim 1. 3. A laser generator (12) serving as a light beam supply source of an optical system, an optical system for forming light that simulates a molten pool formed in a metal material at the time of fusing, and a defect spark generated from a defect. A light source having an optical system for forming light,
The simulated defective spark light source used in the diagnostic method according to claim 1, wherein each optical system is set such that light formed by each optical system is captured as a molten pool and a defective spark.