JP4470173B2 - High speed metal material moving speed measuring device - Google Patents

Description

  The present invention relates to a moving speed measuring device that can accurately measure the moving speed of a high-temperature metal material without contact and has excellent maintainability.

  In the manufacturing process of a metal material, for example, steel material, it is common to solidify molten steel by a continuous casting machine. Since the quality of steel materials is greatly influenced by the solidification process, the production control standards for continuous casting machines are considered to be very strict. Among them, the casting speed, that is, the movement speed of high-temperature steel materials in continuous casting machines is controlled. Are regarded as particularly important management matters.

  Conventionally, in order to measure the moving speed of a high-temperature metal material including the high-temperature steel as described above, a contact-type speed measuring device using a touch roll is generally used. That is, a speed measurement configured to measure the moving speed of the high temperature steel material by bringing the touch roll into contact with the surface of the high temperature steel material and measuring the rotation speed of the touch roll accompanying the movement of the high temperature steel material with a pulse generator or the like. The device is in use.

  However, the touch roll type speed measuring device needs to bring the touch roll into contact with the surface of the high-temperature steel material, which inevitably results in poor maintainability and troublesome maintenance. There is a problem that the measurement accuracy is likely to deteriorate.

  On the other hand, various non-contact type speed measuring devices have been developed in order to solve the problems in the above-described contact type speed device.

  For example, Patent Document 1 discloses a laser Doppler velocity measuring apparatus that measures the velocity of a moving object in a non-contact manner using a so-called Doppler effect. More specifically, when the laser beam emitted from the laser generating means is divided into two by the beam splitter and irradiated onto the moving object from opposite directions, scattering of the moving object corresponding to each light transmission beam is performed. The wavelength of light causes positive and negative Doppler shifts depending on the speed of the moving object. When the scattered light subjected to the two positive and negative Doppler shifts is received by the receiving optical system and converted into an electric signal, an AC signal having a Doppler frequency is present in the electric signal. Since this Doppler frequency is a function of the moving speed of the moving object to be measured, the wavelength of the laser light, and the crossing angle of the two transmitted beams, a configuration for measuring the speed of the moving object by measuring the Doppler frequency is disclosed. Has been.

  Patent Document 2 discloses a speed measuring device that measures the speed of a moving object in a non-contact manner using a so-called laser speckle pattern. More specifically, a laser beam is emitted from a laser light source to a moving object, and a laser speckle pattern reflected from the moving object is detected by a linear image sensor. Then, the laser speckle pattern (output signal) from the linear image sensor is transmitted to the arithmetic unit, and the output signal at a certain time is first stored in the memory and repeatedly read out as a reference signal. The cross-correlation between this and the current signal is calculated, and the axial speckle movement amount of the linear image sensor is calculated as the peak position. And the structure which measures the moving speed of a moving object from this moving amount is disclosed.

Further, Patent Document 3 discloses a speed measurement device that measures the speed of a moving object in a non-contact manner using a video photographing device such as a camera. More specifically, when a moving object is imaged with a video imaging device, and the same object to be detected is captured in continuously acquired still images, the movement distance is calculated by comparing the center of gravity position. Thus, a configuration for measuring the moving speed of the moving object is disclosed.
JP-A-5-40176 JP 2000-275011 A Japanese Patent Laid-Open No. 2002-190027

  Both of the speed measuring devices described in Patent Documents 1 and 2 are devices that use laser light. For example, from the surface of a steel material having a high temperature of 500 ° C. or higher, the wavelength of laser light that is generally used for measuring devices is used. A large amount of light having a wavelength close to (infrared region) is emitted. Therefore, this becomes noise, and there is a problem that the speed measuring apparatus described in Patent Documents 1 and 2 cannot accurately measure the speed of the high-temperature metal material. In addition, the speed measuring device described in Patent Document 1 has a problem that the maintainability is poor because the optical system is complicated.

  On the other hand, since the speed measuring device described in Patent Document 3 uses a video photographing device such as a camera, the problems described in Patent Documents 1 and 2 do not occur. However, unlike moving objects with artificial patterns and colors on the surface, when the target is a high-temperature metal material, what should be the detection object to compare the center of gravity position There is no disclosure or suggestion in Document 3, and it is difficult to use the speed measuring device described in Patent Document 3 as it is for measuring the moving speed of a high-temperature metal material.

  The present invention has been made to solve such problems of the prior art, and provides a moving speed measuring device that can accurately measure the moving speed of a high-temperature metal material in a non-contact manner and has excellent maintainability. The task is to do.

  In order to solve the above-mentioned problems, the inventors of the present invention have made extensive studies. (1) When the surface of a high-temperature metal material such as a high-temperature steel material is imaged, it does not adhere to the pixel corresponding to the portion to which the scale is attached. The area corresponding to the scale is appropriate because the brightness (density) of the pixel corresponding to the part is greatly different (the pixel corresponding to the part to which the scale is attached is bright and the pixel corresponding to the part not attached is dark). If a predetermined pixel area corresponding to is set as a detection target, a characteristic pattern (light / dark pattern) corresponding to the state of scale adhesion is formed on the detection target. Therefore, if a detection target is extracted using a pattern matching method for a captured image after the high temperature metal material has moved and a movement distance per predetermined time of the detection target is calculated, the movement of the high temperature metal material is accurately performed. We found that the speed could be measured. Furthermore, (2) the vicinity of the edge portion of the high-temperature metal material has a large amount of scale attached due to the decrease in temperature, so the pixel region corresponding to the region near the edge portion is the detection target. Therefore, it is difficult to form a characteristic pattern on the detection target, and as a result, the detection target may not be accurately extracted even if a pattern matching method is used for a captured image after a predetermined time has elapsed since the high-temperature metal material has moved. I found it.

The present invention has been completed based on the findings of the inventors. That is, the present invention includes a CCD camera that images the surface of a moving high-temperature metal material, and an image processing device that calculates the moving speed of the high-temperature metal material by performing image processing on a captured image captured by the CCD camera , The image processing apparatus corresponds to a region excluding the vicinity of the edge portion of the high-temperature metal material and a region where the scale exists with respect to the first captured image captured by the CCD camera , and a grayscale pattern corresponding to the presence or absence of scale adhesion A step of extracting and registering a predetermined pixel region in which a pixel is formed as a detection target, and extracting a pixel region having a correlation with the registered detection target for a second captured image captured by the CCD camera after a predetermined time has elapsed. And a separation distance between the pixel area extracted for the first captured image and the pixel area extracted for the second captured image at the predetermined time. In by dividing, there is provided a moving speed measuring apparatus of the hot metal material characterized by performing the steps of calculating a moving velocity of the hot metal.

According to such an invention, a predetermined pixel area corresponding to an area excluding the vicinity of the edge portion of the high-temperature metal material and having a scale and having a gray pattern according to the presence or absence of the scale is detected. It is said. Then, while extracting and registering the detection target for the first captured image, the second captured image captured by the CCD camera after a predetermined time has elapsed (after the movement of the high-temperature metal material) is correlated with the registered detection target. A pixel region having characteristics is extracted. In other words, since the position of the detection target moves within the imaging field of view of the CCD camera as the high-temperature metal material moves, the registration of the second captured image is performed in order to detect the position of the detection target after the movement. A pixel region having a correlation with the detected object is extracted. At this time, as described above, since a characteristic pattern corresponding to the scale state is formed on the detection target, a pixel area (after movement) having a correlation with the detection target using a known pattern matching method. Detection target) can be extracted with high accuracy. Then, the separation distance between the pixel region extracted for the first captured image (that is, the detection target before movement) and the pixel region extracted for the second captured image (that is, the detection target after movement) is the predetermined time. By dividing, the moving speed of the high-temperature metal material is calculated.

As described above, according to the apparatus for measuring the moving speed of the high-temperature metal material according to the present invention, the moving speed of the high-temperature metal material can be accurately measured in a non-contact manner, and includes a CCD camera and an image processing apparatus. Therefore, it has an advantage of excellent maintainability. The elapsed time from when the first captured image is captured until the second captured image is captured is an arbitrary time as long as the registered detection target does not move out of the imaging field of the CCD camera. It is possible to set. That is, until the registered detection object moves out of the imaging field of the CCD camera based on the field of view of the CCD camera , the position and size of the detection object in the first captured image, and the approximate movement time of the high-temperature metal material. Therefore, it is sufficient to set a time that does not exceed the predicted time.

  Preferably, the image processing apparatus is configured to newly extract the detection target and register for update every predetermined time.

As described above, since the registered detection target will eventually move out of the field of view of the CCD camera , a pixel area having a correlation with the registered detection target cannot be extracted from the captured image (second captured image). End up. That is, after the registered detection object has moved out of the field of view of the CCD camera , the moving speed of the high-temperature metal material cannot be calculated.

However, according to the preferable configuration, since the detection target is newly extracted and registered for update every predetermined time, even if the previously registered detection target is moved out of the field of view of the CCD camera , the update is performed. A pixel region having a correlation with the registered detection target can be extracted from the captured image (second captured image), and thereby the moving speed of the high-temperature metal material can be calculated. That is, it is possible to measure the moving speed of the high temperature metal material continuously (over the entire length of the high temperature metal material). Note that the elapsed time from when a detection target is registered first to when a new detection target is extracted and updated is registered, as described above, the previously registered detection target moves out of the imaging field of the CCD camera. Any time can be set as long as it is not. That is, until the registered detection object moves out of the imaging field of the CCD camera based on the field of view of the CCD camera , the position and size of the detection object in the first captured image, and the approximate movement time of the high-temperature metal material. Therefore, it is sufficient to set a time that does not exceed the predicted time.

Preferably, the apparatus further includes a marking device for marking the surface of the high-temperature metal material, the CCD camera images the surface of the high-temperature metal material marked by the marking device, and the image processing device A predetermined pixel area corresponding to an area where marking is present is extracted from the captured image captured by the CCD camera and registered as the detection target.

  Depending on the material of the high-temperature metal material (for example, low carbon steel), the amount of scale generation is reduced. As a result, a characteristic pattern is not formed on the detection target, and the extraction accuracy of a pixel region having a correlation with the detection target is reduced. (As a result, the moving speed measurement accuracy of the high-temperature metal material is reduced).

  However, according to the preferable configuration, the marking device can mark the surface of the high-temperature metal material, and a predetermined pixel region corresponding to the region where the marking exists can be extracted and registered as a detection target. A characteristic pattern corresponding to the marking is formed on the detection target. Therefore, it is possible to accurately extract a pixel region having a correlation with the detection target (and thus accurately measure the moving speed of the high-temperature metal material). Whether or not marking is performed by the marking device is determined in advance by registering, in the image processing device, the material of the high-temperature metal material whose speed is to be measured. In addition to being configured to automatically mark when moving, the operator visually checks the scale generation state, and if it determines that the amount of scale generation is small, it should be marked manually. It is also possible to configure.

  The apparatus for measuring the moving speed of the high-temperature metal material according to the present invention can measure the moving speed of the high-temperature metal material with high accuracy without contact, and can have an excellent effect of being excellent in maintainability.

  Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings, taking as an example the case of measuring the moving speed of a high-temperature steel material in a continuous casting machine.

  FIG. 1 is a plan view schematically showing a schematic configuration of a high-speed steel material moving speed measuring device (hereinafter referred to as “speed measuring device” as appropriate) 10 according to an embodiment of the present invention. As shown in FIG. 1, the speed measuring device 10 according to the present embodiment includes an imaging device 1 that images the surface of the high-temperature steel material S moving in the continuous casting machine (side surface in the width direction in the present embodiment), and the imaging device 1. An image processing apparatus 2 that calculates the moving speed of the high-temperature steel S by performing image processing on the captured image.

  In the present embodiment, the surface temperature of the high-temperature steel S to be measured for the moving speed is about 600 ° C. to 1000 ° C., and the moving speed is set in the range of about 0.6 m / min to 1.0 m / min. ing.

  The imaging device 1 according to the present embodiment is a CCD camera having 640 pixels in the horizontal direction and 480 pixels in the vertical direction, and the optical axis is relative to the surface of the high temperature steel material S at a position about 2 m away from the surface of the high temperature steel material S. The size of the imaging field of view is set to 100 mm horizontal x 75 mm vertical. In this embodiment, since the imaging device 1 is installed at a position sufficiently separated from the surface of the high-temperature steel S as described above, the ambient temperature around the imaging device 1 is about 40 ° C., and air cooling by factory compressed air is performed. It can be cooled sufficiently.

  The image processing apparatus 2 according to the present embodiment captures a captured image of the surface of the high-temperature steel material S captured by the imaging apparatus 1 with 8 bits (256 gradations) at an appropriate timing, and performs image processing on the captured captured image. Thus, the moving speed (casting speed) of the high-temperature steel material S is calculated. Hereinafter, the contents of the processing in the image processing apparatus 2 will be specifically described with reference to FIGS. 2 and 3 as appropriate.

  FIG. 2 is a side view schematically showing the state of the surface of the high-temperature steel S imaged by the imaging device 1 according to the present embodiment. FIG. 3 is an explanatory diagram for explaining processing contents in the image processing apparatus 2 according to the present embodiment. As shown in FIG. 2 or FIG. 3A, first, the image processing apparatus 2 starts with a first captured image captured by the imaging apparatus 1 at an appropriate timing (a region surrounded by a broken rectangle in FIG. 2). This is the imaging field of view, and as described above, the dimensions are 100 mm wide × 75 mm vertical), and the first captured image is a region excluding the vicinity of the edge E of the high-temperature steel S and has a scale. A predetermined pixel region corresponding to the region to be detected (a region surrounded by a solid rectangle in FIG. 2 and its dimensions are 10 mm wide × 60 mm long) is extracted and registered as a detection target. More specifically, the pixels in the pixel region having a predetermined position and size in the captured image so as to correspond to the region excluding the vicinity of the edge portion E of the high-temperature steel material S and the region where the scale exists. Information (density value of each pixel constituting the pixel area) is extracted and stored. Note that, as shown in FIG. 2, the vicinity of the edge portion E of the high-temperature steel material S has a large amount of scale attached due to a decrease in temperature. If an area is set as a detection target, a characteristic pattern is hardly formed on the detection target. Therefore, in the present embodiment, a pixel region corresponding to a region excluding the vicinity of the edge portion E of the high-temperature steel material S is set as a detection target.

  Next, as shown in FIG. 3B, the image processing device 2 takes in the second captured image captured by the imaging device 1 after a predetermined time has elapsed (in this embodiment, every 200 msec), For the two captured images, a pixel region having a correlation with the registered detection target is extracted. More specifically, in the second captured image, a pixel area having the same size as the registered detection target is sequentially scanned, and each pixel in the scanned pixel area and the registered detection target are configured. So that a so-called normalized correlation process is performed with each pixel, and a pixel region having the largest correlation value indicating the degree of coincidence of images is extracted as a pixel region having a correlation with the registered detection target Has been.

  The image processing apparatus 2 uses the pixel region extracted for the first captured image (the region surrounded by the rectangular line shown in FIG. 3A) and the pixel region extracted for the second captured image (FIG. 3B). The distance (space between the center positions of each rectangle) L is calculated. More specifically, in the image processing apparatus 2, actual dimensions per pixel corresponding to the imaging field of the imaging apparatus 1 are registered in advance, and the pre-registered distances calculated in units of pixels are stored in advance. By multiplying the actual size per pixel, the separation distance L is calculated in units of the actual size.

  Finally, the image processing apparatus 2 calculates the moving speed of the high temperature steel material S by dividing the calculated separation distance L by the predetermined time. That is, the moving distance of the high-temperature steel S is calculated by calculating the separation distance L based on the second captured image that has been captured after elapse of 200 msec since the capture of the first captured image, and dividing this by 200 msec. Next, a new separation distance L is calculated based on the second captured image taken after 400 msec from the capture of the first captured image, and this is divided by 400 msec, thereby moving the next moving speed of the high-temperature steel material S. Is calculated. Such calculation is repeated every 200 msec to continuously calculate the moving speed. In the present embodiment, when a sudden change in the moving speed (casting speed) occurs, if the casting speed is controlled in accordance with this, there is a risk of causing a so-called breakout and falling into operation. The moving speed calculated every 200 msec as described above is subjected to moving average processing (for example, the average value of moving speeds for 10 times is calculated every 200 msec), and the moving speed after the moving average processing is output as a measurement result. Based on this, the casting speed is controlled (that is, the casting speed is gently followed).

  As described above, the speed measuring device 10 according to the present embodiment uses a predetermined pixel region corresponding to a region that is a region excluding the vicinity of the edge portion E of the high-temperature steel material S and that has a scale as a detection target. Therefore, a characteristic pattern corresponding to the state of the scale is formed on the detection target. And while extracting and registering the said detection target about a 1st captured image, about the 2nd captured image imaged with the imaging device 1 after predetermined time progress (after the movement of the high temperature steel S), it is the said registered detection target and A pixel region having a correlation is extracted. In other words, since the position of the detection target moves within the same imaging field of view of the imaging device 1 as the high-temperature steel material S moves, the second captured image is used to detect the position of the detection target after the movement. A pixel region having a correlation with the registered detection object is extracted. At this time, as described above, since a characteristic pattern corresponding to the scale state is formed on the detection target, the detection target is detected using a known pattern matching method (in this embodiment, normalized correlation processing). It is possible to accurately extract a pixel region (detection target after movement) having a correlation with the. Then, the separation distance L between the pixel region extracted for the first captured image (that is, the detection target before movement) and the pixel region extracted for the second captured image (that is, the detection target after movement) is the predetermined time. The movement speed of the high-temperature steel material S can be calculated with high accuracy by dividing by.

  In the speed measurement device 10 according to the present embodiment, the image processing device 2 has a predetermined value as shown in FIG. 3C in order to continuously measure (over the entire length) the moving speed of the high-temperature steel material S. The detection target is newly extracted and updated and registered every time. That is, since the detection object registered first (see FIG. 3A) will eventually move out of the field of view of the imaging apparatus 1, it is correlated with the registered detection object from the captured image (second captured image). It becomes impossible to extract a pixel region having. However, if the detection target is newly extracted and updated and registered every predetermined time as in the present embodiment, the previously registered detection target has moved out of the field of view of the imaging apparatus 1. However, since it is possible to extract from the captured image (second captured image) a pixel region having a correlation with the newly updated detection target, it is possible to calculate the moving speed of the high-temperature steel S without interruption. It is. Note that the elapsed time from when the detection target is registered first to when the detection target is newly extracted and updated is registered, as long as the previously registered detection target does not move out of the imaging field of the imaging device 1. An arbitrary time can be set, and in this embodiment, the detection target is configured to be updated and registered about every 7 seconds immediately before moving outside the imaging field of view.

  Moreover, the speed measuring apparatus 10 which concerns on this embodiment is further equipped with the marking apparatus (not shown) which marks the surface of the high temperature steel S as a preferable structure. And the imaging device 1 is comprised so that the surface of the high temperature steel S marked with the said marking device may be imaged (specifically, on the surface of the high temperature steel S in the visual field of the imaging device 1). The image processing apparatus 2 can extract and register a predetermined pixel area corresponding to the area where the marking is present as the detection target for the captured image captured by the imaging apparatus 1. It is configured (whether or not to use a marking device can be selected as appropriate).

  With such a preferable configuration, for example, as a steel material S made of low-carbon steel, as a result of a reduction in the amount of scale generation, a characteristic pattern is not formed on the detection target, and a pixel region having a correlation with the detection target is formed. Even if there is a concern that the extraction accuracy will decrease (and the moving speed measurement accuracy of the high temperature steel S will decrease), the marking device will mark the surface of the high temperature steel S, and it will respond to the area where the marking exists Since a predetermined pixel area to be extracted can be extracted and registered as a detection target, a characteristic pattern corresponding to the marking is formed on the detection target. Therefore, it is possible to accurately extract a pixel region having a correlation with the detection target (and thus accurately measure the moving speed of the high-temperature metal material). In addition, since the well-known thing is applicable variously about the structure of a marking apparatus and the material of a marking medium, the detailed description is abbreviate | omitted here. In addition, as a timing (time interval) for marking, an arbitrary time interval can be set as long as the previously applied marking does not move out of the imaging field of the imaging apparatus 1. In this case, a new marking is made every about 7 seconds immediately before moving outside the imaging field of view.

  FIG. 4 shows a case where the moving speed of the high-temperature steel material (set speed is 0.8 m / min) is measured using the speed measuring apparatus 10 (however, the marking apparatus is not used) according to the present embodiment described above. An example of a comparison result with the case where the moving speed of the same high-temperature steel material is measured by a conventional touch roll type speed measuring device is shown. As shown in FIG. 4, the measured value of the speed measuring device 10 according to the present embodiment (data represented as “present invention” in FIG. 4) and the measured value of the conventional touch roll type speed measuring device (“conventional” in FIG. 4). In any case, the value is almost equal to the set speed, and the measurement accuracy when evaluated in a short time (1 hour in the example shown in FIG. 4) is the same. It can be said that there is. However, when using the touch roll type speed measuring device, as described above, it is necessary to bring the touch roll into contact with the surface of the high temperature steel material. There is a problem that the measurement accuracy deteriorates in the long term due to the wear of the touch roll (if the wear is worn, the outer peripheral length of the touch roll is shortened by that amount, and the measured value becomes larger than the actual speed). On the other hand, according to the speed measuring device 10 according to the present embodiment, the above-described problem does not occur, and the moving speed of the high-temperature steel material can be accurately measured over a long period of time without contact. Since it is composed of an imaging device and an image processing device, it has an advantage of excellent maintainability.

FIG. 1 is a plan view schematically showing a schematic configuration of a high-speed steel moving speed measuring device according to an embodiment of the present invention. FIG. 2 is a side view schematically showing the state of the surface of the high-temperature steel material imaged by the imaging device shown in FIG. FIG. 3 is an explanatory diagram for explaining processing contents in the image processing apparatus shown in FIG. 1. FIG. 4 shows a comparison result between the case where the moving speed of the high temperature steel material is measured using the speed measuring device according to the present invention and the case where the moving speed of the same high temperature steel material is measured using a conventional touch roll type speed measuring device. An example is shown.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Imaging device 2 ... Image processing device 10 ... Moving speed measuring device E ... Edge part S ... High temperature steel material (high temperature metal material)

Claims (3)

A CCD camera for imaging the surface of a moving high-temperature metal material;
An image processing apparatus that performs image processing on a captured image captured by the CCD camera and calculates a moving speed of the high-temperature metal material;
The image processing apparatus includes:
About the 1st picked-up image imaged with the said CCD camera , it corresponds to the area | region except the edge part vicinity of a high temperature metal material, and the area | region where a scale exists, and the predetermined shading pattern according to the presence or absence of scale adhesion is formed Extracting and registering the pixel area of the detection target,
Extracting a pixel area having a correlation with the registered detection target for a second captured image captured by the CCD camera after a predetermined time;
Performing a step of calculating a moving speed of the high-temperature metal material by dividing a separation distance between the pixel region extracted with respect to the first captured image and the pixel region extracted with respect to the second captured image by the predetermined time. An apparatus for measuring a moving speed of a high-temperature metal material.   The apparatus for measuring a moving speed of a high-temperature metal material according to claim 1, wherein the image processing apparatus is configured to newly extract the detection target and register the update every predetermined time. It further comprises a marking device for marking the surface of the high-temperature metal material,
The CCD camera images the surface of a high-temperature metal material that has been marked by the marking device,
The image processing apparatus is configured to extract and register a predetermined pixel area corresponding to an area where a marking exists in the captured image captured by the CCD camera as the detection target. 3. A high-speed metal material moving speed measuring device according to 1 or 2.

Images